I had a request to create a permanent page with all my posts about cardiopulmonary exercise testing in CFS, my own test results, and my experiences wearing a heart rate monitor. What follows are all my posts on the subject in chronological order. If you prefer, you can see the original posts with their comments by using this link.
Stressin’ and Testin’, originally posted April 19, 2012
Exercise testing for CFS is like professional boxing: you know you’ll get the crap beaten out of you, but you volunteer for it anyway. The difference is that in boxing, you get paid. In CFS exercise testing, you just hope to get some useful data. I don’t have the results of my testing yet, but I thought it might be helpful to at least share what the experience was like.
The rationale for exercise testing in CFS comes primarily from the research of the Pacific Fatigue Lab at the University of the Pacific. Their research has shown that people with CFS have a unique response to a two-day exercise challenge compared to healthy sedentary controls or people with other illnesses. In the second test, people with CFS demonstrate significant impairment of their metabolic function. In other words, the testing captures the effects of post-exertional malaise. If you want to read more about this, you can check out the series of articles I wrote on post-exertional malaise in 2010.
The Pacific Fatigue Lab testing calls for two cardiopulmonary exercise stress tests (CPET), spaced 24 hours apart (referred to as the Stevens Protocol). I went to Ithaca College to have my testing done by researcher Dr. Betsy Keller, who has provided the CPETs for CFS research by Dr. Maureen Hanson and Dr. David Bell. I was instructed to rest for several days in advance, and to eat frequent carb-rich snacks of fruits, whole grains, etc.
The test began with blood pressure and EKG measurements taken while I was lying down. Then we moved to the stationary bike. I was fitted with a nose clip and scuba-like mask so that my oxygen and carbon dioxide could be measured and analyzed. The EKG leads were hooked up to another machine so that my heart could be monitored throughout the test. Then I sat on the bike without pedaling for three minutes, so that resting data could be collected. My blood pressure was measured every two minutes throughout the test. I got the order to start pedaling, and every two minutes a little more resistance was added to the bike so I had to work harder as the test continued.
And it was hard. Very hard. The techs were constantly shouting encouragement, telling me how much time was left at each resistance level, goading me to push to the next level. Every two minutes, someone would ask me to rate my level of perceived exertion and that was recorded as well. There was so much going on, all I could do was focus on pedaling the bike. The goal of the test is to pedal until you feel you cannot go any further. Not I-would-like-to-stop-now, but I-will-fall-off-the-bike-if-I-have-to-keep-going.
Once I hit that point, they dropped the resistance from the bike and asked me to pedal a little more to start cooling down. I was just on autopilot at that point, barely paying attention to what was going on. They kept taking my blood pressure to be sure that it started dropping back down to normal. Finally, they helped me off the bike and into a chair to recover. The best part was then being helped into the next room to lie down!
On the next day, we did the whole thing over again. It was definitely more difficult the second day, although I don’t have any data yet to say whether they saw the dysfunction they expected. Once I cooled down from the second test, I was helped to the car and allowed to go home.
I think I will do a separate post about recovering from this test. Suffice to say, it sucks. I just hope the test data will be helpful.
Recoverin’ originally posted May 3, 2012
Three weeks ago, I had my exercise stress tests. A friend had cautioned me that it could take three weeks to recover, and I think she was right although I did sabotage myself a little bit, as I’ll explain.
I was not prepared for how bad the post-test crash would be. I mean, I knew it would be bad but this was possibly the most intense crash I have ever had. I was completely bedridden for three days, and was unable to sit up longer than the time it took to eat (in bed). The pain was excruciating, especially in my legs. My brain was fuzzy, and I could not focus on anything. But it was the weakness that really shocked me. I felt like a Raggedy Ann doll, my limbs all floppy. When I stood, I felt like I should sit right back down. My arms tingled with that weird pins-and-needles feeling I get before I pass out, although I did not faint. I could not hold my head up for very long without support. To get to the bathroom, I had to resort to my old castigation mind-trick: “You are not paralyzed. There is nothing wrong with your muscles. You can’t wet the bed like an invalid. Get off your a** and walk to the bathroom.” (It occurs to me that I would never speak to a sick person this way, but that self-reflection probably merits its own post.)
I’ve had a day or two of crashing as severe as this many times over the last 17 years. But this crash went on for days. I’ve never gone as long as a week with that floppy spaghetti-noodle weakness in my limbs. I started to get a little scared. What if the exercise test broke something in me? What if this never got better? Both my friend and Dr. Betsy Keller had said that some patients benefited from IV fluids after the exercise tests. I’ve never tried it before now, but after five days I was feeling desperate to try anything to break the pattern. My doctor agreed, and I went to his office for the infusion. Another first: I have never used a wheelchair to get to his office before. He even ran the line himself, and I received 2 liters of IV saline over the course of three to four hours. After the nurse hooked up the second bag and increased the drip rate, my head started to clear a little bit. Then the floppy feeling started to dissipate. By the time my Mom brought me home, I did feel a little better, despite the energy expenditure of going to the office.
I felt like I turned a corner after that. I still could not be out of bed for very long. Standing at the sink for five minutes was too much. Getting up to put away a couple books brought on the now-familiar weakness. But I could sit up in bed and read, focus on a movie, or knit for awhile. That was a huge improvement. Then came the Hot Water Heater Episode, and I had a setback. I was back to being bedridden for a couple days, unable to stay upright without support. But by the end of week two, I did experience a little improvement. The pain in my legs was back down to pre-test levels. I no longer felt like I might pass out. And I started to feel a little bored, always a good sign for me. There is no doubt I was still crashed, but I started to think I might actually climb out of this one.
Then I sabotaged myself, a little. Long before my exercise test was scheduled, my parents had purchased handicapped-accessible tickets for my husband and I to accompany them to a baseball game. I still wanted to go. In fact, when my husband and I discussed whether I was physically able to go, I told him I couldn’t handle the emotional consequences of not going to the game. I was scared, unsure what the outing would do to my recovery and how bad the setback might be. But I threw caution to the wind and went anyway. I am so very glad I did! We had a blast, and it is always such a gift to get out in the world after a prolonged relapse. I’m sure that it has added days to my recovery. I’ve spent these last few days “resting aggressively.” Tomorrow is our 16th wedding anniversary, and I don’t know if I will be able to go out to dinner to celebrate.
My understanding is that a recovery time of more than one day after exercise testing is considered abnormal. In one study, none of the CFS patients recovered within 48 hours and 60% of CFS patients took more than 5 days to recover. That particular study only followed patients for 7 days post-testing, so it is likely that many of those patients took more than a week to recover. I think three weeks was a reasonable estimate for me. If I hadn’t indulged in the baseball game, I might be pretty close to baseline by now.
Instead, it’s three weeks out and I am writing this from bed. As soon as I publish this post, I will lie back down as I feel my head getting heavier – the concrete football helmet of fatigue. I won’t attempt anything more demanding than knitting for the rest of the day, and have some audiobooks to fill the time. Whether we go out to celebrate our anniversary will be a last minute decision, and I have already mentally allocated next week to more bed rest. I hope I can be back at baseline by the end of the week, but as anyone with CFS knows, I am ultimately not in control of whether I make that deadline.
And The Envelope, Please, originally posted on May 14, 2012
My exercise test results are in. The numbers were, quite frankly, shocking. Two numbers – VO2max and anaerobic threshold – provide the evidence that I have significant metabolic dysfunction, and I’ll try to explain what they mean. Check out my description of the test itself for background. What I do now that I have the results will be the subject of my next post.
VO2max is a measurement of the maximum amount of oxygen that a person can use during exercise. The more oxygen you can use, the more energy you can produce. VO2 max is considered the best measurement of a person’s physical fitness or functional capacity, and it is affected by factors such as age, gender, training, altitude, etc. A sedentary woman my age has an average of 27.0. My VO2max was 20.7 on day one, and 19.6 on day two. In other words, my maximum ability to use oxygen is 23% lower than what would be expected for a sedentary woman my age.
One interesting thing about my VO2max number is that I was able to reproduce the result on day two. Typically, people can reproduce their VO2max value on a two-day test with about 6-7% of variation. My number was about 5% different. So this is a good thing, but not necessarily typical of CFS patients. One study found that CFS patients had a drop of 20% in their VO2max on the second test day.
Dr. Betsy Keller of Ithaca College, who conducted my exercise test, included functional equivalents in her report to help translate the numbers into information I could actually understand. Looking at just the VO2max number, my capacity equates to slow cycling, but carrying groceries upstairs exceeds my functional capacity. That’s pretty grim.
Anaerobic threshold is where things get really interesting. The anaerobic threshold is the point at which your body is producing most energy through anaerobic metabolism, as opposed to aerobic metabolism which uses oxygen. This means that you will feel increasing fatigue, your workload will drop, and you will have to stop activity within a few minutes. It also takes longer to recover from this kind of activity, requiring rest and more oxygen. (Is this sounding familiar to anyone?)
On day one, my anaerobic threshold occurred at 105 beats per minute. That is not horrible, although it is low. A deconditioned but otherwise healthy person might have a result like that. On day two, however, my anaerobic threshold dropped to 93 beats per minute. That is abnormal, not just because it is low but because it represents such a significant drop from day one. Healthy people, even deconditioned people, are able to reproduce their anaerobic threshold results on day two. That I failed to do so is proof of metabolic dysfunction.
When you put the VO2max result together with the anaerobic threshold result, you can see the metabolic dysfunction another way. Normally, the anaerobic threshold will occur at about 50-75% of a person’s VO2max. But for me, my anaerobic threshold on day one occurred at 30% of VO2max. Anything below 40% is considered an abnormal result and evidence of metabolic dysfunction. On day two, my anaerobic threshold occurred at 17% of VO2max. That is crazy low. In fact, I reached that anaerobic threshold just sitting on the bike before I started pedaling on day two. Just sitting there, I was already maxed out. These are grossly abnormal results.
To equate these numbers to functionality, Dr. Keller said that my day one anaerobic threshold is the equivalent of standing to fold laundry, or putting clothes in the washer, but that walking around to put away laundry would be beyond my capacity. But on day two? The day two result is the equivalent of lying down watching television. So when I am in a crash, I am exceeding my anaerobic threshold by just lying down and watching tv or doing nothing.
So no wonder I feel like shit all the time, yeah?
There were other abnormalities, including blunted heart rate and blood pressure responses, but these two numbers are the key for me. As Dr. Keller points out, most activities of daily living require me to work above my anaerobic threshold. This means my ability to perform those activities is limited, and resulting fatigue prevents me from continuing to perform those activities.
Here’s the killer fact for me, though. On day two, I was at my anaerobic threshold before I even started cycling. Then I proceeded to cycle for 11.5 minutes, and came close to the length and workload I produced on day one. The whole second day was past my anaerobic threshold. I felt and rated day two as more difficult, but I kept going anyway. I draw two conclusions from this. First, I have become accustomed to operating over my anaerobic threshold and have probably developed that as an adaptive coping mechanism. Second, I cannot trust my my own assessment of when I am overdoing it. My sense of how I am feeling is not reliable.
My husband’s reaction to that was “Duh.” It will surprise no one who knows me that the test proves I am a stubborn and determined woman who does not accept her own limitations. But it was a shock to see this reduced to numbers and written in black and white on the page.
A friend pointed out to me that nothing has actually changed. It’s not like I’ve suddenly developed a heart condition. The only thing that has changed is the information I have about the metabolic dysfunction. Knowledge is power, and next time I’ll share what steps I’m taking to apply this knowledge.
Significance of AT, originally posted May 21, 2012
Now that my exercise tests are finished and I have the results, it’s time to figure out what to do about it. I’m relying on the work of Staci Stevens, Chris Snell and others at the Pacific Fatigue Lab who have done a great deal of work on CFS metabolic dysfunction and how to cope with it. Everything revolves around my heart rate at the anaerobic threshold.
The anaerobic threshold (AT) is the point at which most energy is derived through anaerobic processes (as opposed to using oxygen) and lactate begins to accumulate in the bloodstream. As people cross their ATs, they are not able to sustain activity for much longer and experience the rapid onset of fatigue. People with CFS seem to have lower than normal ATs due to metabolic dysfunction, although no one can yet pinpoint where the dysfunction is. While a healthy person can get through work and other activities of daily living without reaching the AT, people with CFS can reach it just by taking a shower. As a result, we experience fatigue much earlier than healthy people and we continue to build up that oxygen debt as we eat, sit, walk up stairs, and so on. Any activity has the potential to cross the AT, building up yet more need for rest. It’s no surprise that we end up prostrate in bed, unable to do anything at all.
Rest and oxygen are necessary for recovery after crossing the AT, but people with CFS do not recover normally. Here’s an example that Staci Stevens gave in an article I wrote in 2010:
An athlete can climb two flights of stairs without fatigue or shortness of breath. A sedentary overweight person might climb the same two flights of stairs and feel out of breath, but will recover completely after a brief rest. A person with CFS may struggle to climb the stairs, and experience severe fatigue and PEM. In other words, the CFS patient reaches the AT after much less exertion than a healthy person, and requires a longer period of time to recover.
People with CFS end up in trouble from two directions. On the one hand, we cross our ATs abnormally early. And on the other hand, it takes us abnormally long to recover. It’s a vicious cycle, and I suspect that many of us spend large chunks of time over our ATs. I saw that in my own test results. One day two, I crossed my AT before I started biking and then biked for 11.5 minutes – all over the AT!!!
Common sense says that if something is bad for you, don’t do it. So the first step is to avoid crossing the AT. Obviously, we can’t spend our days hooked up to EKG and ventilation equipment to carefully monitor our ATs. But we can use heart rate as a proxy for the AT. My heart rate at the anaerobic threshold on day one was 105 beats per minute, and 93 beats per minute on day two. I am now wearing a heart rate monitor (this one) with the alarm set to go off when my heart rate goes over 95 beats per minute.
When the alarm sounds, I am supposed to sit down and rest until my heart rate drops back down. I’m also keeping notes on my activities so I can begin to pinpoint my true limits. If I can avoid my AT, I should be able to avoid taxing my body and triggering post-exertional malaise. Heart rate is not the perfect proxy. For example, my heart rate as I write this blog post is 79 beats per minute, and I will still be fatigued afterwards. But heart rate can at least help get my physical activity more in line with my capacity.
It’s been very surprising to see what activities push my heart rate over 95 beats per minute. Here’s a sample:
- Walking from the back of my yard up an incline to the house
- Rolling an empty trashcan up the driveway
- Pulling weeds for two minutes
- Walking up stairs at my normal pace
- Standing at the reception desk at a doctor’s office
- Laughing really hard (I’m giving my self a break on that one)
The first goal is to get my activity under control. Sometimes I won’t have a choice about going over the AT, like when I go to the doctor this week. But there are a lot of things I would normally be trying to do – weeding, laundry, going to our small farmer’s market – that I am not doing because it sets off the heart rate monitor. It will take some time to see if this really does help minimize my crashes.
Raising the Limit, originally posted May 29, 2012
I feel like I am getting close to baseline, the state I was in prior to the exercise testing. It’s taken almost seven weeks, and in that time I have left my house a total of seven times – 5 doctor appointments and 2 social outings in my wheelchair. It has been a hard slog back to normalcy, and I’m getting close.
I’ve been wearing a heart rate monitor for 18 days, and have the alarm set to go off when I go over 95 beats per minute. It does not take much to put me over that line. I’ve been so frustrated that it goes off when I climb a flight of stairs or laugh or walk through my yard. But that alarm has forced me to pace much more than I normally would. I am walking slower. I’m making different choices about what I try to accomplish in the house. And that alarm has stopped me from doing things I would normally have pushed to do, like weeding for even 5 minutes or planting flowers in the yard. I have done far far less than I was inclined to do.
Has it made any difference in my symptoms? Perhaps. I have not had a crash day since strapping on the monitor. But my fatigue, pain, and cognitive symptoms all persist. Nothing is off the charts, but none of it is gone, either. On the other hand, I have been coming back to baseline and I think it makes sense to attribute that progress to the careful pacing forced by the monitor.
Today I raised the limit on my heart rate monitor to 105 beats per minute. This was my anaerobic threshold on the first day of the exercise tests. Now that I am feeling closer to normal, I thought it made sense to experiment with the higher limit. If I can sustain that without crashing, perhaps it will be a sign of progress. So far today, I have been able to climb the stairs and water some plants in the yard without setting off the monitor for more than a couple of beats.
The anaerobic threshold is not the only barrier I am trying to avoid. There is what I am calling the crazy threshold (CT) to manage as well. The crazy threshold is that point at which I can’t take being isolated in this house for another minute. The past few days have been ok. My husband was home for most of the holiday weekend instead of running in several directions at once. We went out for ice cream at the dairy right by the house. And my parents came for a visit too. I’ve had enough human interaction that I don’t feel perilously close to the CT.
This week, I am in self-imposed seclusion and house arrest. We have a wonderful family event to attend on Saturday that will also involve a car trip. It will be a big outlay of energy, and I
cannot WILL NOT miss it. I don’t think I will be resentful of the heart rate monitor if careful pacing gets me to and through this family celebration without a crash. Too much to hope for? We’ll see.
Can’t Drive 95, originally posted July 2, 2012
Almost as soon as I had decided to raise the limit on my heart rate monitor to 105 beats per minute, my physical therapy team smacked that idea down. They told me that one week with the monitor was not enough to really get the hang of pacing, and suggested that I was raising the limit so the monitor would not go off as frequently rather than because of any real improvement in my energy management. On their advice, I set the alarm back down to 95 beats per minute.
They were right.
One week was not enough. Neither is one month. My activity sets off the alarm multiple times a day. Climbing stairs, carrying objects, making the bed, moving anywhere too quickly – it all sets off the alarm. I tracked my activity, position and heart rate carefully for several weeks. And I tried – I really really tried – to make different choices and limit my activity.
It worked, sort of. After recovering from a family event, I went three weeks without a crash. My pain levels have decreased. I haven’t ended each day crawling into bed at 6:30 pm, shaking and exhausted. But this came with a price. I did not leave the house for those three weeks. I was much less productive than normal – just more inactive overall.
And I was miserable. I worried about the long-term effect of being even less active than before. I was bored, so terribly bored. I realized that pushing hard to exhaustion actually prevents me from feeling bored. If I’m completely wiped out, my brain can’t care about the fact that I’m spacing out to a baseball game. It doesn’t bother me when I’m too tired to care. But now I’m aware/awake enough to notice that I’m doing nothing, thinking nothing, and that I’m bored.
I feel the bars of this prison more acutely. It’s like standing outside a bakery and looking at the goodies in the window. I can see the things I want to do, but I can’t touch them without setting off the monitor. So I stand at the glass and stare. I want to fuss in the garden, tidy up, bake bread, cook dinner, write more blog posts, read read read the stack of articles in my queue, take photos, visit with friends – and I can’t. Not without hearing the boo-doop chime of the alarm. These are all things I did before, and I accepted the consequential pain and exhaustion. Now I am not doing them, and struggling to accept the consequential boredom, loneliness, and despair.
It’s a trade off, either way. But which is the right choice? When is it better to be bored? When is it better to be in pain? Living with CFS is always about moving targets, shifting limits, and hard choices. Wearing the heart rate monitor is designed to help me stop before I get to pain and post-exertional relapse. When I obey the alarm, it works; I experience much less pain and relapse.
But is it worth it?
What kind of life is it to stop halfway up 13 steps to rest? To not be able to cook and then also do the dishes? To not kick the ball around the yard with the dog for a few minutes? To say no, no, and no again to invitations and fun plans? To shrink my world so that I’m not free to move within my own home without a chime sounding? To sit and sit and sit and sit and sit and all the time knowing that I am sitting while opportunities slip by?
There are people with CFS who are bedridden. I am fortunate to have only suffered that way for short periods of time. But when I have been that ill, I have been so hazy and weak that I didn’t really notice. It’s like the first few days after acute gastroenteritis, where you’re not throwing up (which is good) but you can’t do anything else (and you don’t care).
Living with this heart rate limit is not like that. This feels like a cruel experiment. There’s a plate of cookies on the table in front of me, and I want a cookie. But every time I reach for the cookie, I get a powerful electric shock. So I sit, looking at the cookies, acutely aware that I can’t have one. I’ve made these adjustments before. When I gave up my job. When I gave up driving. When I gave up cooking dinner for friends. When I gave up walking more than 50 yards and submitted to using a wheelchair. I’ve been there, done that. And each time, it did not feel optional. I gave those things up because to continue doing them meant unbearable pain and exhaustion. But these day to day life things that set off the heart monitor are not like that. No single thing – carrying a few books up stairs, kicking the ball for the dog – puts me down. But cumulatively, or done for too long, these things do knock me out, and the heart monitor can prevent that.
What I’ve learned since strapping on the heart rate monitor is that the glass box of my limitations is too small. If I obey the monitor, if I focus on setting it off as little as possible, I will lose my mind. I will sink into deep depression, isolated and unsatisfied. I will resent the healthies in my life. I will surrender more of myself to this greedy illness, and I will live each day focused on what I cannot do rather than on what I can. The longer I wear this monitor, the more clear it becomes to me that I cannot abide the speed limit of 95 beats per minute.
Edited to add: My friend Wilhelmina Jenkins posted a comment on Facebook that I’ve posted with her permission below, but one sentence really captures how I feel: “How long can you stare at the cookies in the window without feeling that you are starving to death?”
Spontaneity, originally posted on August 2, 2012
I’ve always been a planner, and living with CFS wreaks havoc on plans. I never know if I’ll be able to follow through on plans, big or small. I missed my cousin’s high school graduation, and at least three weddings of friends from law school. But I’ve also had to cancel on lunch with friends, movies, dates with my husband, errands . . . and it’s not just planned outings (which are few and far between anyway). I frequently reach 4pm and I’m too spent to make dinner. The tidying up I planned to do? Putting away clean laundry? Making that phone call?
Anyway, you get the picture. Making plans when you have CFS is frequently a crap shoot (or an exercise in futility).
Since strapping on the heart rate monitor, I feel like this crap shoot effect has been quadrupled. There are times I can’t make another trip up the stairs, not because of how I’m feeling but because my heart rate is running too high. I am working so hard at being disciplined, obeying the alarm and resting. This past weekend was very busy, and I rested up for almost two weeks – passing on other things – to have the energy to make it. (I did make it, but I’m still crashed).
My life is becoming increasingly regimented: obey the alarm; don’t do X so that you can do Y in three days; no impulsive baking (or anything else); no spur of the moment visits from friends. Being housebound, I have always had limited options. My husband will ask “What do you want to do tonight?” and I will say “Same options as every other night: knit, read, or watch tv.” There’s never been freedom for variety or novelty. But now, I feel like I’ve gone from “severely limited” to “carefully controlled energy microclimate.” The lack of flexibility and spontaneity is oppressive.
Then there was last Monday. My heart rate was running really low (for reasons I still don’t understand). I was able to go up the stairs without triggering the alarm. I didn’t feel good, but I felt stable. My husband took a day off from work, and we decided SPUR OF THE MOMENT to go out to lunch. Like normal people! All spontaneously and everything!
And I did it! We had lunch, and my heart rate alarm (which I left audible despite being in public) only went off when I was walking from the car to the restaurant and then back out. It’s hard to describe to people who are not housebound how this feels. All I can say is that doing something as mundane and normal as going out to lunch with my husband makes me feel like a human being.
But the best moment came afterwards when my husband went into the local soccer store. I was waiting in the car, and he came back out to tell me that there were two players from the Philadelphia Union in the store. We are serious Union fans. Did I want to meet them? So I went into the store (alarm binging now) and met Leo Pajoy and Roger Torres. They were quite gracious, and even posed for a picture. It doesn’t happen often when living with CFS, but sometimes spontaneity works out just fine.
Preemptive Rest, originally posted on August 28, 2012
I continue to wear my heart rate monitor every day, and generally listen to its alarm. When it starts to sound, I sit down (although not instantaneously I will admit). And when I hit the part of the day where it goes off every time I get up or move around, I know I’m done for the day. If I’m lucky, it’s after dinner. But I’ve found that whenever I am really active, the trigger-happy time of day comes earlier. I don’t know for sure, but it seems to me that once I’ve used up whatever energy stores I have, my heart rate rises more easily and stays elevated. A constant alarm is a pretty hard signal to ignore, and if my family is around it’s impossible. One good thing about the alarm: my husband and family are insistent about my listening it. Double edged sword, that, since it’s impossible to get away with overdoing it.
Today, I started the next phase of incorporating my true anaerobic threshold into my daily life: preemptive rest. In his self-help course, Bruce Campbell says that preemptive rest is one of the most important tools for people with CFS. Preemptive rest, or rest to prevent symptoms, is scheduled rest taken regardless of how you feel. By resting before you feel tired, it is possible to reduce symptoms and improve stamina. In the context of the anaerobic threshold, resting before reaching that threshold gives your body a chance to recover from activity before you have gone into “oxygen debt.” In theory, this might increase the sustainable amount of overall activity by rebuilding energy stores before they are depleted.
I’m skeptical. I don’t doubt that the theory has merit. I’m skeptical about my ability to follow through with it. Lying down when I’m not tired seems like a waste. My capacity is so limited, it seems pointless to take a break before I get tired. Along with scheduling preemptive rest, my physical therapist believes that limits on the length of time I spend at any activity will also help. She says that I should take a break after 20 minutes of any activity, but I pushed back on that one. Take a break after 20 minutes on the computer? I can’t get through my email in 20 minutes. I also worry about losing my train of thought. It takes such concentration to write. If I have to take a break every 20 minutes, I’ll have to gear that concentration back up over and over. I would much rather work on a task to completion. I also resist such a regimented approach to getting through the day. Again, my capacity is already so limited that it’s hard to apply even more restrictions to myself.
So we negotiated a compromise. I will take two scheduled rest breaks a day: 20 minutes in the morning and 40 minutes in the afternoon. I will take rest breaks after 20 minutes of physical activity. This means breaking tasks like making dinner into smaller chunks and extending it over more time. And I will take a break after one hour on the computer. I’m tracking my activity, heart rate and symptoms every 30 minutes this week. It’s a laborious pain in the arse, but I don’t think I will stay on track without that kind of record keeping. Otherwise, I’ll just lose track of what I’m doing and how long I’ve been at it.
I took my scheduled rest today, but I did not experience any difference in my stamina or symptoms. It’s only been one day, so it’s impossible to draw any conclusions. I suspect that the benefits from this will only become evident over time, possibly over several weeks. I just hope I have the patience to see it through.
Adapting, originally posted on August 31, 2012
I remember my mother and grandmother canning every year. My grandmother would put up jars of peach halves and applesauce, and my mother made strawberry jam. It always seemed like a silly waste of time to me, since you can buy all those things in a store. But canning is a thing now, and on a whim I decided to try it a couple years ago. One batch of strawberry jam and I was hooked. I can’t explain it, but there is something extraordinarily satisfying about hearing the ping of jars sealing because then you know you’ve done it right.
But canning is a high energy activity. There are several places in the process where you can’t stop for a break. The boiling water in the canner heats up the kitchen. Many recipes require constant stirring. I always dissolved into a puddle on the floor after a canning session. The day I turned 50 pounds of tomatoes into 13 quarts of tomato sauce comes to mind as an example of the insanity.
When I started using the heart rate monitor, canning was one of many hobbies that seemed completely incompatible with this new way of pacing. Certainly my old way of canning is now impossible. But could I adapt the process to be more heart rate friendly? My husband bought a peck of peaches at our local farmer’s market, so I decided to give it a shot. Here’s what happened:
- Gather equipment (canner, funnel, tongs) and wash jam jars. Move very slowly so you don’t set of the heart rate monitor.
- Sit down for 10 minutes.
- Blanch peaches.
- Sit down for 5 minutes.
- Peel peaches and chop. Mix peaches with lemon juice and hope they won’t turn brown while you rest.
- Lie down for 15 minutes.
- Drink a large glass of water.
- Drag chair over to stove so you can sit while you stir the jam. Make jam.
- Wonder how sick women managed to survive on the frontier. Decide that they didn’t.
- Remove jars from boiling water. Wonder why no one has invented a better jar lifter that makes you less likely to scald yourself.
- Fill jars with jam. Quietly exult that there is one half-jar of jam that will have to be consumed immediately.
- Add lids and move jars back to the canner.
- Drink a large glass of water. Resist the burning urge to do all the dishes. Lie down for 10 minutes instead.
- After jars have boiled for 10 minutes, remove lid and turn off heat. Start the dishes.
- After 5 minutes, remove jars from the canner and wait for that lovely PING! as the lids seal. Finish the dishes.
- Collapse on the couch.
- Test jam on a piece of toast.
- Wonder how you got a splatter of jam on the back of your tshirt.
- Admire your lovely jars of jam.
Did taking rest breaks make it easier? Yes. My heart rate monitor went off a couple times, but never for very long and the highest it went was 100 beats per minute. I was still exhausted at the end of the process, but I don’t think it was quite as bad as previous canning sessions. That may just be wishful thinking since I don’t have hard data from past years for comparison. My pre-heart rate monitor canning would have taken 1.5 hours. Adding in the rest breaks extended it to 2.25 hours.
I think I’ll pat myself on the back for giving this a try. Rather than assume that this hobby is off limits because of the way I used to do it, I tried to adapt it to my limitations. It’s bittersweet because I was happy to be doing it, but also frustrated that I couldn’t work as fast as I did before. It would be easier if I could recruit help (anyone want to wash my dishes?). And I doubt I’ll be tackling monster projects like 13 quarts of tomato sauce. But I’m really proud of my peach jam, and it will taste better for the effort that went into it.
Imperfect, originally posted September 7, 2012
I’ve had a craptastic week. Three crash days, including one that involved a three hour “nap.” I don’t understand what triggered these crash days, but I never do. Usually, crash days take me by surprise because whatever activity I’ve been doing just doesn’t seem to be significant enough to cause a crash. My husband is rarely surprised by my crash days; he’s always had a better sense of my limitations.
Last week I made jam and had a doctor’s appointment. We had a family dinner to go to on Sunday, so I did very little on Friday, Saturday and Sunday – I just sat on the couch knitting and watching soccer. The crashing started on Monday, and seemed to get worse through Wednesday. I completely gave in on Wednesday, taking that three hour nap and just spacing out the rest of the time. I had hoped to write several blog posts this week, and maybe work in the garden for a few minutes. I did none of this, and am writing this post from bed.
Through all of this, I have been monitoring my heart rate. With two exceptions, my heart rate was good last week. I generally stayed under 95 beats per minute, and when I did go too high I immediately stopped what I was doing to rest. On both Wednesday and Sunday, I left the house which meant showering, drying my hair, applying makeup. On both days, my heart rate soared as high as 110 beats per minute during the process of getting ready. I took rest breaks (shower, rest, dry hair, rest, get dressed, rest, etc.) to bring my heart rate down, but then it would jump when I moved to the next step in the process. It was frustrating to say the least. On both Wednesday and Sunday, I had several episodes where my heart rate was high and I briefly felt like I might pass out. And on both days, my heart rate stabilized while I was out of the house to around 87 beats per minute.
So were those episodes the cause of these crash days? Was it the high heart rate while I was getting ready? Or was it the near fainting episodes? Both? Or was the crash the result of leaving the house twice? Or that plus making jam? Or none of the above? All of it? This, in a nutshell, is the maddening part of living with CFS. Despite everything I have learned about pacing, despite monitoring my heart rate carefully, I still have crash days. And because life is not a carefully controlled experiment, I don’t know which component or combination of conditions caused the crash days.
I hate crashing. I hate being unable to do simple things like sitting upright to knit, or talking to friends on the phone. I hate being unable to accomplish the things on my modest to do list. I hate the feeling that I am just taking up space and using resources without producing anything or giving something back. And I hate not knowing – after all these years – how to avoid crashing.
Using a heart rate monitor for pacing is an imperfect system. The monitor can’t capture the energy drain of cognitive and emotional activity. And despite my staying within the heart rate limits and breaking activities into pieces for an entire week, just two hours of elevated heart rate was possibly enough to cause three crash days. The heart rate monitor is imperfect, and I am most definitely imperfect in applying that system.
You know what else I hate? Complainy blog posts. I don’t like writing them, and I assume people don’t like reading them. So I will end this on a positive note. A friend called me yesterday from the store to ask what I needed. I couldn’t think of anything, but she insisted. When she dropped off the fruit I asked for, she also brought me flowers for no other reason than that I had a bad week. This friend has struggles of her own, but she took the time to take care of me this way. It turned my whole week around, because now I feel profoundly grateful instead of defeated. It’s the love and support of my family and friends that makes this illness bearable.
Rest Medicine, originally published November 28, 2012
I have been working really hard at resting. That probably doesn’t make sense, but I have been struggling to incorporate preemptive rest into my routine and it feels like a lot of work. The rationale for preemptive rest is that scheduled breaks help your body restore its energy capacity because you are not pushing to the point of exhaustion. Bruce Campbell explains preemptive rest very well, and credits it as a key component of his own recovery.
I was very resistant to trying it. My functional window of opportunity is so small and fleeting. Why should I interrupt an activity to rest, especially when I feel like I can keep going? I’ve always been a power-through-it kind of person, and I’ve approached CFS the same way. Taking two scheduled breaks a day to lie down and rest, regardless of how I feel, has been a huge emotional disruption. I hate this daily reminder that I am weak. I hate feeling like a sick person who has to lie down after an hour on the computer. I don’t want to need this rest. I shouldn’t have to need it. I should be able to overcome these limitations, not feed them or cater to them. When I started taking these rest breaks, I hated it so much I would lie on my bed and fume about it (and yes, that defeats part of the purpose of resting).
But I wanted to give this method a fair trial. I knew I had to change the way I think about the rest breaks in order to get any benefit from it. I thought about treatments for other diseases and how those patients probably don’t enjoy the process either. If I had cancer, I would hate chemotherapy but I would do it. In fact, I think I would attack chemotherapy with a “let’s do this!” attitude. Cancer? Screw cancer, give me the chemo – I’ll take it and kick cancer’s ass. Rather than seeing preemptive rest as a burdensome imposition, would it help me to treat it as a daily medicine?
I don’t get pissy about taking my medications; I need them, so I take them on schedule every day. But I am still struggling to feel that way about preemptive rest. For example, I should lie down right now but I want to finish this blog post before lunch. I’m at war with myself every day because my expectations and desires are always bigger than my energy capacity. No matter how short my list is, no matter how much I have reduced my expectations, I never accomplish everything on my list. Taking rest breaks feels like a disruption and waste of time.
Would I resent chemo like this? All the horrible side effects and agony of chemo have a purpose: to rid you of cancer. I see my medications the same way: I take pain medication and it helps my pain. I am trying to bring the same attitude to preemptive rest. The rest breaks are necessary, just like my pain medication, and I should embrace it as another part of my arsenal. I realize that it might take months to see benefits from any treatment, whether it’s chemo or a new pain medication or rest breaks. I know I have to stick with it, and part of that process is adopting a positive attitude towards a method designed to help me. I am working hard, every day, to give rest breaks a fair chance.
Update (11/30/12): After I published this post, ME/CFS Self-Help Guru posted about reframing challenges in a positive way.
Insufficient Data, originally published December 4, 2012
One of the most frustrating aspects of coping with CFS is the lack of definitive data. A PubMed search for “chronic fatigue syndrome” yields 4,877 results (as of today), but as a patient on the front lines I have to make treatment decisions based on theory, supposition, and anecdotal evidence.
Case in point: I’m wearing a heart rate monitor and reducing my activity to stay below my anaerobic threshold based on a few studies that show CFS patients have disruptions in their energy metabolism. There is even a published case study showing that following this pacing method and short duration exercise leads to improvement in functional capacity and activity recovery. But because my anaerobic threshold is so low, I exceed my heart rate limit just by climbing 12 steps. An expert advised me to reduce my activity to stay below the heart rate limit, even if it meant stopping halfway up the steps to rest or using a shower chair. Another expert endorsed the use of beta blockers to lower my heart rate. That topic is worthy of a separate post, but there are patients who have benefited from this approach. Sue Jackson has written excellent posts about her experience doing just that, and she credits beta blockers with drastically improving her functional capacity. When I asked the first expert about beta blockers, the expert responded that beta blockers would not change my actual anaerobic threshold but would mask when I was exceeding my limit by lowering my heart rate.
So how do I decide what to do? Expert One advises significantly reducing my activity to obey the heart rate limit, and not using medication to lower the heart rate. Expert Two advises using the medication to lower heart rate in order to increase my activity levels. There is no research that definitively answers this question. There have been no case control studies or systematic long-term follow up. Both experts can support their theories with anecdotal patient data. Both experts can support their theories with sound reasoning. There is simply no data that answers the question: which method is better for my health?
Large treatment trials, longitudinal studies, and sophisticated research into etiology and disease course drive treatment decisions for many diseases and conditions. If I had breast cancer, detailed analysis of the tumor would tell my doctor which chemotherapy regimen to use and for how long. If I had a broken hip and a heart condition, a physical therapist would be able to prescribe a rehab program suitable for both conditions. If I was HIV positive, triple therapy would be prescribed and tightly monitored to make frequent adjustments.
But those of us with CFS are left flapping in the wind. I think even the best CFS expert doctors in the country would acknowledge that treating people with CFS involves a lot of trial and error, educated guesses, and fine-tuning. The CFIDS Association recently stated that CFS patients on Patients Like Me report trying over 800 different treatments. This is insane! It’s like throwing spaghetti at the wall to see how much will stick.
Making CFS treatment decisions should be like playing sudoku – there might be some trial and error, but there is inherent logic to the puzzle. Instead, making these decisions feels like the Sunday New York Times crossword on steroids, with incomprehensible clues and multiple right answers. No one can get all the right answers based on insufficient data. Should I take the beta-blockers, or should I buy a shower chair? Your guess is as good as mine. Literally.
Comparing Exercise Advice, originally published January 18, 2013
Exercise is an issue for every CFS patient, and there is no shortage of advice on whether and how to do it. On January 14th, the CDC hosted a conference call as part of its Patient Centered Outreach and Communication Activity (PCOCA) efforts. Dr. Nancy Klimas and Dr. Connie Sol presented their exercise advice for people with ME/CFS. I’ve seen some sharp criticism of the presentation, so I thought it would be helpful to compare their advice to the recommendations from Dr. Christopher Snell’s group at the Pacific Fatigue Lab. Dr. Snell and his collaborators (Staci Stevens, Todd Davenport, Mark Van Ness) have done the most work on exercise capacity in CFS, and published a conceptual model for safe exercise in 2010. You can learn more about their work in this webinar they gave last year.
Why Do It?
It’s common knowledge that exercise is an important part of preventing heart disease, diabetes, and osteoporosis. And I think most CFS patients would be eager to exercise if it did not make us sick. On Monday, Dr. Klimas said that deconditioning explains much of the dysautonomia seen in CFS. I think she may have overstated it because there are physically fit people who develop POTS, NMH or other orthostatic conditions, but deconditioning certainly wouldn’t help. Dr. Klimas described herself as the “perfect advocate to talk about exercise” because of her decades of research and clinical experience focused on biomarkers and immune function. She does not believe exercise is the only possible treatment for the disease (unlike proponents of the psychosocial model), but she also does not think it should be ignored.
I should note that while Drs. Klimas and Sol use exercise to provoke PEM so they can measure the gene expression cascade that follows, they have published no papers on exercise physiology in CFS. Snell and his group have published multiple papers on the topic, including a study that shows deconditioning is not the cause of PEM. Despite showing that there is metabolic dysfunction unique to CFS, Snell and many other experts recommend being as active as is safely tolerated. Stronger muscles will lead to less pain. Being as physical fit as possible will improve our chances with heart disease and other long-term consequences. If we can safely tolerate a certain kind or level of activity, we should do it. The emphasis must be on the word SAFE, and activity should be tailored to each individual patient’s capacity.
Identifying a Target Heart Rate
My articles on PEM and exercise explain the body’s energy systems and the importance of heart rate in detail. For purposes of this post, I can say that both Klimas and Snell agree that heart rate at the anaerobic threshold is the limit for safe activity in CFS. So how do we identify the correct heart rate?
Dr. Sol uses a single test in which the patient exercises to exhaustion. Multiple measurements help identify the heart rate at the anaerobic threshold, and then that heart rate is used to design an individualized exercise protocol. Dr. Snell and Staci Stevens use a two day maximum exercise test to do the same thing. That second test is critical because CFS patients’ metabolic function declines significantly after the first test. In my own case, my heart rate at the anaerobic threshold went from 105 on day one to 95 on day two. Under Sol’s system, 105 beats per minute would be my maximum heart rate, but that would be too high on any day that I was not well rested. My personal view is that by skipping the second test, Sol and Klimas are at risk for setting the safety limits too high for most patients.
Not everyone can take a two-day exercise test (for a variety of reasons), so there is a simple calculation for guessing at your heart rate at the AT. Klimas and Sol recommended: 220 minus your age times 60%. In my case, (220 – 44) x 60% = 105.6 bpm (matching my AT on day one). Stevens recommends 50%, or (220 – 44) x 50% = 88bpm (lower than my AT on day two). Here’s the problem with the calculation: a bedridden patient would not have the same limit as me (housebound) or a friend of mine (who can leave the house every day). We’re all sick with CFS; we all have metabolic dysfunction. But it’s unlikely that our heart rate limits are identical. Patients must be cautioned that the calculation is a guess only; careful experimentation is necessary to establish your safe level.
Defining Safe Activity
Both Sol and Stevens agree that the safe level of activity is the level that does not produce symptoms. Dr. Sol said that she knows she has prescribed the right level of activity when the patient reports that he/she feels no difference. Stevens has said that any symptom flare that lasts more than a few hours is too much and that activity must be scaled back.
What qualifies as exercise? Both Sol and Stevens agree that activities of daily living should be seen as exercise. The effort required to cook a meal or shower can raise your heart rate too high, and may need to by modified to stay in the safe zone. They both agree patients should examine the activities that make them tired, and try to adapt and pace those activities. Dr. Klimas said that these methods will lead to a more even, reliable supply of energy; Dr. Snell has said the same thing.
Beyond activities of daily living, Sol suggested yoga or non-weight bearing activities such as water exercises. She recommended starting with a minute or two of activity followed by a few minutes of rest, repeated five times once a week to start. In contrast, Stevens recommends a more modest starting point of stretching and range of motion exercises. Patients should advance to low intensity, short duration activity only if the stretching is well tolerated. For Snell and Stevens, heart rate is not the only indicator of capacity. Patients must pay attention to their perceived level of effort, and avoid activities (or activity duration) that feels “somewhat hard.”
There is no question that there are CFS patients who are too sick to come to a lab and pedal a bike for eight minutes. Accordingly, these patients have not been studied for metabolic dysfunction and exercise capacity. Drs. Klimas and Sol made no comment on Monday about what these patients could or should do. I interviewed Staci Stevens as part of the research for my article on exercise, and based on her advice I wrote:
A bed bound patient may need assistance to turn in bed or complete basic activities such as showering, but heart rate biofeedback can help identify the appropriate pace and duration of these activities. Bed bound patients can also try deep diaphragmatic breathing, perhaps six deep breaths at a time. Deep breathing will lower heart rate, and also work the large muscles of the diaphragm. Severely ill patients might begin with passive stretching, where a physical therapist or caregiver moves the patient’s limbs slowly and carefully to gently stretch muscles and try to improve flexibility.
This must be done very cautiously. There is simply no published data that investigates the metabolic dysfunction in bedridden CFS patients or that explains what they can do safely. The cost of trial and error can be high, so patients should be very careful.
Reasonable and realistic expectations are an important part of any rehabilitation effort. Snell and his group describe the goal as being as active as possible within toleration, and hopefully this will lead to a more predictable energy supply (eliminating the push-crash cycle). In contrast, Dr. Klimas said on Monday that patients will show improvement if they follow the program, and that when they stay below the AT they feel “much better.” Then Dr. Klimas claimed that some patients have been able to return to work or athletics. This is an extraordinary claim, especially in the absence of published data. How impaired were these patients to start with? How long did they follow the program, and was the program standardized across patients? Did these patients show objective improvement on subsequent exercise testing? How long did their improvement last?
Personally, I was very surprised to hear Dr. Klimas make this claim. She is quite familiar with the severity of the disease, the dearth of treatments, and the danger of false hope. In my opinion, claiming that pacing with a heart rate monitor and slowly progressing exercise is curative in the absence of published data is misleading, at best. The notion that exercise will make us all better is pervasive and potentially harmful to patients. Show me the data.
There are many similarities between the advice of Klimas and Sol on the one hand and Snell and Stevens on the other. Both sides agree that patients should be as active as they can safely tolerate. They agree that activities of daily living should be seen as exercise. Both recommend using a heart rate monitor to pace activity by staying under the anaerobic threshold. Both recommend starting very slow with exercise, and avoiding exercise that increases symptoms.
There are also some differences. The two groups calculate the safe zone differently, with Klimas and Sol potentially setting limits higher than patients’ anaerobic thresholds. Klimas and Sol offered no advice to bedridden or other severely incapacitated patients, while Snell and Stevens offer at least a little guidance. Finally, Snell and Stevens do not suggest that their program is curative in any way. They suggest a cautious but realistic goal of eliminating the push-crash cycle. In contrast, Dr. Klimas was quite expansive in her claim that her program had helped some patients return to work.
Despite their differences, both groups give the same basic advice to CFS patients: use a heart rate monitor to help you recognize when you are doing too much; ensure adequate rest; be as active as you can without triggering symptom flares or post-exertional malaise. This is a good starting point, but I hope that one day we will have access to physical therapists and others trained to help us navigate these limits. From my own experience, trying to apply this expert advice on my own has been unnecessarily frustrating.
Meeting METS, originally published June 21, 2013
It has been more than a year since I had a two-day exercise test. My exercise test report was full of all kinds of jargon, and over the last year I have been trying to decode and apply it to my pacing. One of these concepts is “METS,” a measurement of the effort needed to do an activity, and correlating my results to the real world has been nothing short of shocking.
METS is the Metabolic Equivalent of Task, and is a measure that expresses the relative energy cost of activities, with a MET of 1 equal to sitting quietly. Walking at a slow pace has a MET of 2, meaning that walking slowly costs twice as much energy as sitting quietly. In exercise testing, METS is calculated from the maximum amount of oxygen consumed (VO2max), although it is not intended to perfectly correlate to an individual’s metabolism. But for purposes of understanding the relative costs of different activities, and estimating parameters of an individual’s functional capacity, METS is used as a standard measure.
In my exercise testing, my VO2max (which is the maximum amount of oxygen I consumed) correlated to 5.9 METS. This means I can’t do any activity that requires more work than 5.9 METS because my body can’t perform that level of work. My anaerobic threshold (as I’ve previously explained) was very low. A healthy person with a maximum METS of 5.9 should cross the anaerobic threshold between 3.0 and 4.425 METS. In the first test, I switched to anaerobic energy at 1.9 METS. In the second test, my anaerobic threshold occurred at 0.92 METS. Needless to say, this is abnormally low!
The real value of METS is in understanding the energy cost of activities relative to each other. The Compendium of Physical Activities is a list of the METS of numerous activities, and provides a way to look at the intensity or work capacity needed for those activities. When I took the METS results from my test and applied it to the Compendium, I was shocked to see the kinds of activities that are outside my functional capacity.
As I said, my absolute maximum capacity is 5.9 METS. This means I should not attempt any activity over that limit. Examples of activities out of my reach include scrubbing a bathroom with vigorous effort (6.5 METS), moving household items upstairs (9.0 METS), carrying 16-24 pounds up stairs (6.0 METS), or shoveling snow (6.0 METS). Many of the activities are things that I have long since given up on ever doing again, such as hiking (7.8 METS) or swimming slow laps (6.0 METS).
It is more shocking (devastating?) to see the activities over my functional capacity at my anaerobic threshold. On the first test, my AT occurred at a METS of 1.9. This means that any activity over 1.9 METS requires me to rely on anaerobic metabolism. As a result, I can’t sustain those activities for very long and I experience severe and disproportional fatigue afterwards. So I have to be very cautious with those activities, even on non-crash days. What kinds of activities are over the 1.9 limit?
- mild stretching (2.3 METS)
- Hatha yoga (2.5 METS)
- general kitchen activity (3.3 METS)
- light cleaning (2.5 METS)
- washing dishes (2.5 METS)
- cooking, moderate effort (3.5 METS)
- changing bed linens (3.3 METS)
- container gardening (2.3 METS)
- light weeding (3.5 METS)
- playing piano (2.3 METS)
- showering (2.0 METS)
- walking at a slow pace (2.8 METS)
These are basic tasks of living. Some of these I don’t have to attempt (like changing bed linens) because I am fortunate to live with a helpful husband. But if I lived alone? I know so many patients who live alone and have to expend all their energy just doing the basic chores of daily living, and then spend time recovering from them. The METS limit also helps explain why walking at a slow pace has been so difficult for me. I can do it for a short time, but with caution and the risk of crashing. Now I know that it is over my AT limit of 1.9 METS, so OF COURSE it is difficult for me.
Not surprisingly, the activities I spend the most time on are under the 1.9 METS limit. Sitting and watching tv (1.3 METS), reclining while reading (1.3 METS), and knitting (1.3 METS) are all in that safe zone. But as my exercise report noted, when I am crashed my AT occurred at < 1.o METS, which means lying down and doing nothing, or even sleeping, is at or above my limit. The other important thing to note is that METS and the Compendium are both focused on physical activities. I have found no way to measure cognitive load or capacity.
A healthy person spends most of her time under the anaerobic threshold, even while exercising. When she finally crosses her AT, she experiences the rapid onset of fatigue and will stop the activity and rest. And even if she reaches her maximum oxygen consumption and bonks, she will recover to normal within a day or two.
My exercise test shows that my entire energy system is broken all along these stages. I spend most of my time over my anaerobic threshold, except for when I am sitting and reading or knitting. Because I spend so much time over my AT, I have become accustomed, even immune, to increasing fatigue and the signals to stop and recover. And I bonk on a regular basis, without ever approaching my VO2max.
In the last year, I have had to examine all of my activities and modify where I could to try and accommodate these limits. But I don’t live in a world where I can stop washing dishes and cooking and showering. I don’t want to give up slow walking or baking or light gardening just because it is over my AT. Over many months, I have used the heart rate monitor, METS Compendium and a perceived exertion rating of “somewhat hard” to control my physical activity levels. I know it is not practical (or desirable) for me to live below the AT/1.9 METS limit. But I have really struggled to find the right balance between the two extremes of never getting off the couch and cooking/gardening/walking until I bonk. It seems like there should be a big slushy middle ground, but I have struggled to find it.