Exercise Intolerance

siberiantarragon

I'm sure this will be a controversial topic. Does anyone else have it? I've suspected for years that I have it and recent events have stoked my suspicions even more. I've always walked a lot (an hour or more per day) with no ill effects. But every time I try to do anything more intense than that, I end up having some pretty bad physical effects. I've never been overweight and there shouldn't be any reason I should have this level of problems.

In November I started training for a 5K and weightlifting -- nothing too intense though. I started slowly with 1 mile walk/jogging. Then after a few days I worked up to 1 mile jogging, then 1 mile running, and finally I worked up to 1.5 miles running at about a 9:30 per mile pace. This was usually on a treadmill, but I did run on the local track sometimes. I also did about 10 minutes of various weight exercises afterwards. So nothing crazy.

Within a few weeks of starting this, I got sick and I've been sick for almost a month (needless to say my workout routine has been on hold ever since). I'm mostly better now but not fully recovered. I got flu followed by bronchitis followed by COVID. It's the sickest I've been since I got H1N1 in 2011. I haven't gotten COVID or bronchitis ever before and haven't gotten flu since probably 2013. I haven't gotten majorly sick the entire pandemic even living in one of the hardest hit areas. The only thing that changed in my routine was starting to work out.

This isn't the first time either. Every time I work out I get something, whether it's a contagious illness, chronic muscle injury (I was starting to get those after just a couple of weeks working out this time, too), extreme fatigue where I can barely function the whole rest of the day after working out, or even chronic condition (in high school after joining the track team I lost my period for six months and when it came back it was heavier with debilitating cramps, which had never happened before -- I was later diagnosed with PCOS).

I would love to be really fit and muscular but it just doesn't seem possible for me. Anyone else have the same problem?

yirara

Feeling very sick and fatigued after covid has been described. It's also been described for other severe viral infections. So far that doesn't sound too unusual. I think this also plays a role in cfs/me, but I'm not quite sure. Do you have enough rest days when you exercise, e.g. one day light exercise, next day rest, maybe even two days rest? Does the same happen then?

I also have exercise intolerance, but it's a different kind. After lots of tests with a doctor I'm pretty sure now that my body is mainly using glucose as energy, and that one has a limit. I do know that all my jogging for the past 2 years, and likely since I started 8 years ago has been around or above the anaerobic threshold. So further investigations will follow.

siberiantarragon

yirara wrote: »

Feeling very sick and fatigued after covid has been described. It's also been described for other severe viral infections. So far that doesn't sound too unusual. I think this also plays a role in cfs/me, but I'm not quite sure. Do you have enough rest days when you exercise, e.g. one day light exercise, next day rest, maybe even two days rest? Does the same happen then?

The problem isn't being sick and fatigued after having COVID. I worked out during the weeks BEFORE I got sick. I haven't resumed working out yet post-COVID. I'm barely even out of the quarantine period yet. The problem I'm describing is that whenever I start getting a workout routine under way I get some kind of serious health problem. This particular time I got the worst series of respiratory illnesses I've gotten in 12 years. I barely got sick during the whole pandemic prior to this and when I did get sick it was pretty mild, and I never got COVID or bronchitis before and haven't gotten the flu in years. Then suddenly I get all three in a month, one after the other, within weeks of starting to work out. So it's a reasonable conclusion that mild working out destroyed my immune system in a matter of weeks for some reason. Other times I've tried working out I've gotten other health problems which I delineated. I'm wondering why this is and if anyone else has this problem.

I also have exercise intolerance, but it's a different kind. After lots of tests with a doctor I'm pretty sure now that my body is mainly using glucose as energy, and that one has a limit. I do know that all my jogging for the past 2 years, and likely since I started 8 years ago has been around or above the anaerobic threshold. So further investigations will follow.

Do you get reduced immunity or other chronic health issues when you start working out?

yirara

siberiantarragon wrote: »

yirara wrote: »

Feeling very sick and fatigued after covid has been described. It's also been described for other severe viral infections. So far that doesn't sound too unusual. I think this also plays a role in cfs/me, but I'm not quite sure. Do you have enough rest days when you exercise, e.g. one day light exercise, next day rest, maybe even two days rest? Does the same happen then?

The problem isn't being sick and fatigued after having COVID. I worked out during the weeks BEFORE I got sick. I haven't resumed working out yet post-COVID. I'm barely even out of the quarantine period yet. The problem I'm describing is that whenever I start getting a workout routine under way I get some kind of serious health problem. This particular time I got the worst series of respiratory illnesses I've gotten in 12 years. I barely got sick during the whole pandemic prior to this and when I did get sick it was pretty mild, and I never got COVID or bronchitis before and haven't gotten the flu in years. Then suddenly I get all three in a month, one after the other, within weeks of starting to work out. So it's a reasonable conclusion that mild working out destroyed my immune system in a matter of weeks for some reason. Other times I've tried working out I've gotten other health problems which I delineated. I'm wondering why this is and if anyone else has this problem.

I also have exercise intolerance, but it's a different kind. After lots of tests with a doctor I'm pretty sure now that my body is mainly using glucose as energy, and that one has a limit. I do know that all my jogging for the past 2 years, and likely since I started 8 years ago has been around or above the anaerobic threshold. So further investigations will follow.

Do you get reduced immunity or other chronic health issues when you start working out?

No, I don't, I just can't exercise as long as other people without eating tons of glucose, and not as fast.

The immunity problem, and being very exhausted after exercise might be due to chronic fatigue syndrome/me. You want too much from your body, and hence it's more susceptible to all sorts of bugs floating around. There might also be a lot of other reasons for it, but I'm not a doctor. But that's why I asked whether you really start slow and have enough rest days for your body to fully recover. When I do strength training I need 2 days rest to recover from it. I just feel the exhaustion and know I should not push it.

KL1887

So based on the title for this I thought yes that’s me, I have Exercise induced anaphylaxis, I’m about as intolerant to exercise as you can get. Then realised it’s not.

There is such a thing as exercise intolerance and post exercise malaise, but they don’t actually cause you to become ill with coughs/colds, it’s more a particular set of symptoms around being exhausted, in pain, nauseous, weak. The post exercise malaise kicks in any pre existing conditions about a day or two later.

For myself I have problems with my immune system, that causes me post exercise malaise, something as simple as walking to get my kid from school will cause the need for complete rest for two days after because my body will be in pain, stiff and other issues. If I were to take my kid to school everyday for a couple of weeks I would get home from an AM school run and sleep until it was time for the PM one simply because my body wouldn’t be able to cope, it would take not doing the school run for several weeks and a lot of sleep/rest to get me back to basic functioning again. Prior to my immune problems beginning I was extremely fit and healthy.

I haven’t seen anywhere in your post that you’ve spoken to a doctor about a pattern of behaviour in your body that occurs when/after exercise, maybe make an appointment.

penguinmama87

yirara wrote: »

siberiantarragon wrote: »

yirara wrote: »

Feeling very sick and fatigued after covid has been described. It's also been described for other severe viral infections. So far that doesn't sound too unusual. I think this also plays a role in cfs/me, but I'm not quite sure. Do you have enough rest days when you exercise, e.g. one day light exercise, next day rest, maybe even two days rest? Does the same happen then?

The problem isn't being sick and fatigued after having COVID. I worked out during the weeks BEFORE I got sick. I haven't resumed working out yet post-COVID. I'm barely even out of the quarantine period yet. The problem I'm describing is that whenever I start getting a workout routine under way I get some kind of serious health problem. This particular time I got the worst series of respiratory illnesses I've gotten in 12 years. I barely got sick during the whole pandemic prior to this and when I did get sick it was pretty mild, and I never got COVID or bronchitis before and haven't gotten the flu in years. Then suddenly I get all three in a month, one after the other, within weeks of starting to work out. So it's a reasonable conclusion that mild working out destroyed my immune system in a matter of weeks for some reason. Other times I've tried working out I've gotten other health problems which I delineated. I'm wondering why this is and if anyone else has this problem.

I also have exercise intolerance, but it's a different kind. After lots of tests with a doctor I'm pretty sure now that my body is mainly using glucose as energy, and that one has a limit. I do know that all my jogging for the past 2 years, and likely since I started 8 years ago has been around or above the anaerobic threshold. So further investigations will follow.

Do you get reduced immunity or other chronic health issues when you start working out?

No, I don't, I just can't exercise as long as other people without eating tons of glucose, and not as fast.

The immunity problem, and being very exhausted after exercise might be due to chronic fatigue syndrome/me. You want too much from your body, and hence it's more susceptible to all sorts of bugs floating around. There might also be a lot of other reasons for it, but I'm not a doctor. But that's why I asked whether you really start slow and have enough rest days for your body to fully recover. When I do strength training I need 2 days rest to recover from it. I just feel the exhaustion and know I should not push it.

This feels very familiar to me. It is incredibly annoying to run up against my own limitations and realize I am not invincible. 🙃

In my case I think it's strongly related to sleep. For formal exercise I get up very early in the morning. If I've had a break in my routine (lately because I had a baby) and want to get back to it, I have to make sure I'm adjusting when I go to bed in the evenings and not be waking up too many times during the night. Otherwise I almost invariably get a cold or something similar. Once it's part of my routine and I am regularly sleeping well, I can work out no problem. 💪

ETA: Not saying this is you, OP, but it occurs to me that at least in the northern hemisphere where it's winter and peak respiratory illness time, you have a lot of people drastically revising their nutrition, exercise routine, and sleep schedule all at the same time. Seems like peak opportunity for various illnesses to present themselves and be more annoying than usual with the added stress on the body.

snowflake954

You don't say what your life is like, but just a thought--gyms have many people using the same space and breathing intensely. If you aren't used to this type of contact, it could be this. There are lots of germs circulating in closed spaces. Your immune system might be weaker.

As for running, what kinds of temps are you running in? You might just be sensitive there too.

I'd try exercising at home--stay away from the gym.

AnnPT77

Have you had a full medical workup to assure that everything is in normal range: Not just blood chemistry, but nutritional issues (D, B12, more), thyroid, etc., etc.?

How is your nutrition, especially protein and micros (from food)? How is your sleep? Are you supplementing anything potentially to the point of megadosing in combination with diet? Might you be routinely eating certain foods that can be problematic for some or all (such as some types of fish/seafood)?

Also, how much stress is in the rest of your life, and are you someone sensitive to stress generally? (That's not a diss. Different people legit have different responses to different stimuli, different points of emotional focus, etc. Lots of different things are normal and OK, but can have individual implications.)

Exercise is a stressor, in any dosage, and of course intense exercise (as measured against current fitness level) is a bigger stressor. Yes, it's a potentially productive stress, but it still has a cumulative effect on short-term well-being in combination with other stressors.

I know from your posts here that you're an insightful and knowledgeable person, and I'm not suggesting you need to answer any of the above questions on the thread. They're just some of the things I try to think about myself, when I'm seeing responses in myself that seem unusual, given the stimulus.

I hope you can find a solution!

siberiantarragon

yirara wrote: »

The immunity problem, and being very exhausted after exercise might be due to chronic fatigue syndrome/me. You want too much from your body, and hence it's more susceptible to all sorts of bugs floating around. There might also be a lot of other reasons for it, but I'm not a doctor. But that's why I asked whether you really start slow and have enough rest days for your body to fully recover. When I do strength training I need 2 days rest to recover from it. I just feel the exhaustion and know I should not push it.

I did start slow but I only took about one rest day per week (and I would walk on the rest days). I didn't feel particularly exhausted though. I have gotten really exhausted from exercise in the past, like when I took martial arts it would wipe me out for the whole day. But that's why I was working my way up really slowly over time with the distance and speed of my running (my goal was to run a 5K in under 30 minutes in March). I'm not sure if that is CFS/ME or not.

KL1887 wrote: »

So based on the title for this I thought yes that’s me, I have Exercise induced anaphylaxis, I’m about as intolerant to exercise as you can get.

Wow I didn't even know that existed. Sorry that you have that, that sounds really scary.

There is such a thing as exercise intolerance and post exercise malaise, but they don’t actually cause you to become ill with coughs/colds, it’s more a particular set of symptoms around being exhausted, in pain, nauseous, weak. The post exercise malaise kicks in any pre existing conditions about a day or two later.

For myself I have problems with my immune system, that causes me post exercise malaise, something as simple as walking to get my kid from school will cause the need for complete rest for two days after because my body will be in pain, stiff and other issues. If I were to take my kid to school everyday for a couple of weeks I would get home from an AM school run and sleep until it was time for the PM one simply because my body wouldn’t be able to cope, it would take not doing the school run for several weeks and a lot of sleep/rest to get me back to basic functioning again. Prior to my immune problems beginning I was extremely fit and healthy.

I have had post-exercise malaise before which is why I was taking it slow with working out. Chronic fatigue does affect the immune system though so maybe it is related if I do have that?

I haven’t seen anywhere in your post that you’ve spoken to a doctor about a pattern of behaviour in your body that occurs when/after exercise, maybe make an appointment.

Honestly some people have been so mean to me about it in the past when I mentioned it (specifically people who are really into fitness and think that anyone can do hard workouts and if you can't you're just lazy and making excuses) that I didn't want to bring it up to a doctor because I thought they would just be cruel and dismissive. I expected a lot more hate in this comments section based on past experiences but maybe after the pandemic people have become more understanding about these kind of issues.

penguinmama87 wrote: »

ETA: Not saying this is you, OP, but it occurs to me that at least in the northern hemisphere where it's winter and peak respiratory illness time, you have a lot of people drastically revising their nutrition, exercise routine, and sleep schedule all at the same time. Seems like peak opportunity for various illnesses to present themselves and be more annoying than usual with the added stress on the body.

I had pretty much the same nutrition, somewhat healthier and lower glycemic but same amount of calories, and the same sleep schedule as always.

snowflake954 wrote: »

You don't say what your life is like, but just a thought--gyms have many people using the same space and breathing intensely. If you aren't used to this type of contact, it could be this. There are lots of germs circulating in closed spaces. Your immune system might be weaker.

As for running, what kinds of temps are you running in? You might just be sensitive there too.

I'd try exercising at home--stay away from the gym.

I was exercising in the gym in my apartment building. I would usually go in the late evening when nobody else was there but sometimes if I went earlier in the evening there would be one or two people. However there were never more than two other people there besides me and they were always over six feet away. The gym is room temperature and I think all the times I ran outside, which was only a couple of times, it was above 40 degrees. I hate to run outside in the extreme cold. I didn't get sick from the gym, my partner brought the flu home from work, and we're not sure where we got COVID but I hadn't even returned to working out at that point because I was still recovering from bronchitis.

AnnPT77 wrote: »

Have you had a full medical workup to assure that everything is in normal range: Not just blood chemistry, but nutritional issues (D, B12, more), thyroid, etc., etc.?

I had some blood tests done in July for thyroid, blood count, fasting glucose, triglycerides, etc. but it didn't test all the vitamins and hormones. Everything they did test was normal though. I take vitamin D3 every day so I'd be surprised if I was deficient. My immune system improved a lot after I started taking vitamin D3 in 2020.

How is your nutrition, especially protein and micros (from food)? How is your sleep? Are you supplementing anything potentially to the point of megadosing in combination with diet? Might you be routinely eating certain foods that can be problematic for some or all (such as some types of fish/seafood)?

Also, how much stress is in the rest of your life, and are you someone sensitive to stress generally? (That's not a diss. Different people legit have different responses to different stimuli, different points of emotional focus, etc. Lots of different things are normal and OK, but can have individual implications.)

My nutrition and sleep were pretty much the same as they were during the rest of the pandemic when I didn't get seriously sick, or even improved from how they were in the past. And my stress levels had actually improved from how they were in the summer and fall.

pridesabtch

Curious, you said your nutrition remained mostly the same. Were you eating back your exercise calories or a portion of them. Fuel is important. Just a thought. Hopefully you figure this out.

siberiantarragon

pridesabtch wrote: »

Curious, you said your nutrition remained mostly the same. Were you eating back your exercise calories or a portion of them. Fuel is important. Just a thought. Hopefully you figure this out.

Yes I ate back my exercise calories (there wasn't a huge difference in the amount of calories I needed to eat though because I replaced my old exercise of walking with running and weights). But what I meant is the overall kinds of foods I was eating remained similar.

MikePfirrman

I workout six days a week (seven if you count walking my dogs and walking another 2 to 3 miles on Saturday). I also got a RSV, the flu and a stomach virus. Not the sickest I've been in a decade (like you), but it was brutal. My wife also got 3 things this Winter, a lot of people have!

When I workout too hard, I tend to get run down and sick. It's just your body telling you that you are seriously out of shape. Just go super, super slow. Your body will slowly adapt, likely. Perhaps it's just your body telling you that you need to take it easier than most do. I have a strong feeling that it was just bad timing this Winter with the worst flu season in decades and the first time we had it with COVID.

For my first 40 years, I told myself I had asthma because the way I'd wheeze when I ran. Guess what? I do have allergies, but not asthma. I was just completely out of cardio shape. Got to the point (very, super gradually) that I was doing 10 mile hardcore trail races.

Now, there is a very small percentage of people that don't recover well. My wife is one. She has Fibromyalgia. She can workout like 3 to 4 days a week, but no more. There are things that do help with recover, even for her.

Research just came out (now it was funded by the Almond board, so who knows) that almonds can help you recover. D-Ribose is one of the best things to take for recovery. So are BCAAs (branch chain amino acids). Stay hydrated and also make sure you're getting quality sleep.

MikePfirrman

I reread your comments above. Having a hormone panel by a Functional doc would be, I think, very helpful for you.

What I learned when my wife had Fibromyalgia is that most Functional docs look to see if your Cortisol levels in the AM are in the basement. I expected hers to be elevated. It wasn't. It was so low it wasn't funny. There are stages to Adrenal Fatigue. Your cortisol levels are higher for years and then, it's like your body burns out and stops producing Cortisol. According to our Functional doc at that time, she told us that's what she expected to see on her Hormone panel (and that's exactly what it was). She said that's when people, especially women, start to feel so bad that they seek Functional docs. By the way, conventional docs were useless. Completely and utterly useless.

We spend a few thousand upfront because insurance doesn't cover most Functional medicine, but in the long run, it was a fantastic investment in her health. She's in full remission now. The good news is you don't seem to be in a health state that's not able to be completely turned around or managed.

The prescription by functional docs is similar. Adrenal herbal formulations, full spectrum Methyl B Vitamins, D-Ribose. The diet parts are toughest. Eliminate most sugar, sweeteners, vegetable oil, all gluten and dairy. I'd consider getting a food allergy test too. Once my wife got rid of her food allergies, it was an amazing difference. Many find hormone replacement a life saver (she never went that route, concerned with breast cancer risk). Another thing that helps is the antivirals -- Monolaurin is a game changer for many.

She even started a Facebook support group years ago (got to 3K members before she shut it down -- got to be too much for her). Every single person that did these things got significantly better if not completely better.

cwolfman13

I think the illnesses are likely more a coincidence rather than caused by exercise. This is the worst flu season in decades and we have RSV and COVID on top of that. Almost everyone I know personally has had a pretty bad bout of illness or and/or multiple raspatory viral infections at some point this winter.

As your exercise goes, you may think you're taking it slow, but it doesn't actually appear that way to me. The higher intensity of work you do, the more rest and recovery you need, especially when you're at a relatively low level of fitness. For running I would recommend following a structured running program like C25K...they are typically 8-9 weeks and will build you up slowly. Going from walking to jogging a mile in a week is a pretty rapid progression...it isn't slow. A C25K program will at least get you jogging for 30 minutes straight, but in my experience it wasn't a complete 5K...it took me many more weeks to get my actual 5K time down to 30 minutes.

For the gym I would also recommend a structured program. Following structured training beginner programs will help you progress your fitness at an appropriate rate and will minimize the risk of over training, subscribe rest and recovery, etc. Most of what you describe looks like classic overtraining for your current fitness level, not exercise intolerance.

siberiantarragon

MikePfirrman wrote: »

I workout six days a week (seven if you count walking my dogs and walking another 2 to 3 miles on Saturday). I also got a RSV, the flu and a stomach virus. Not the sickest I've been in a decade (like you), but it was brutal. My wife also got 3 things this Winter, a lot of people have!

I know we're having the tripledemic and all but I thought the winters of 2020 and 2021 were supposed to be much worse illness wise. I did get sick in the winter of 2021 and had a lingering cough for a while but the illness itself was much less bad. I didn't get sick in the winter of 2020 even though I was going out a lot and drinking/eating unhealthy food more than usual (FOMO after months of lockdown lol). Also my partner got flu and COVID also but recovered a lot more quickly.

When I workout too hard, I tend to get run down and sick. It's just your body telling you that you are seriously out of shape. Just go super, super slow. Your body will slowly adapt, likely. Perhaps it's just your body telling you that you need to take it easier than most do. I have a strong feeling that it was just bad timing this Winter with the worst flu season in decades and the first time we had it with COVID.

For my first 40 years, I told myself I had asthma because the way I'd wheeze when I ran. Guess what? I do have allergies, but not asthma. I was just completely out of cardio shape. Got to the point (very, super gradually) that I was doing 10 mile hardcore trail races.

I was going super slow though. The weird thing is that I had these problems even when I was in better shape. When I was on the track team in high school I was doing track practice for two hours a day. I lost my period for six months (when it came back it was much heavier and more painful too and has been that way ever since) and also had constant repetitive stress injuries.

I also always had problems with my lungs. No matter how good my times got (and they were pretty decent, my 5K PR was 24:20 which improved from 30+ minutes when I first started, and would have been even faster if I didn't get injured so much) I would always feel like I wasn't getting enough air the entire time I was running. It never improved, not even a little bit. When we did a VO2 Max test in middle school I also had one of the worst in the class and the only people worse than me were people whose parents were smokers, even though I wasn't overweight or anything. So perhaps there is some kind of problem with my lungs and respiratory system and that's why the stress of running led to me getting sick. Particularly that I ended up getting bronchitis which I never got before. That would also explain why I'm fine with walking even for very long distances (as a teenager I used to walk 6 to 10 miles a day regularly) because that doesn't involve getting out of breath. So maybe it's more of a respiratory problem than a muscle one or something.

MikePfirrman wrote: »

I reread your comments above. Having a hormone panel by a Functional doc would be, I think, very helpful for you.

What I learned when my wife had Fibromyalgia is that most Functional docs look to see if your Cortisol levels in the AM are in the basement. I expected hers to be elevated. It wasn't. It was so low it wasn't funny. There are stages to Adrenal Fatigue. Your cortisol levels are higher for years and then, it's like your body burns out and stops producing Cortisol. According to our Functional doc at that time, she told us that's what she expected to see on her Hormone panel (and that's exactly what it was). She said that's when people, especially women, start to feel so bad that they seek Functional docs. By the way, conventional docs were useless. Completely and utterly useless.

This actually makes some sense to me because I've felt burned out, brain fog, etc. since right after I graduated college. No matter what I tried I could never get my energy levels or concentration back to how it was before. It's like I expended all my energy on graduating college (I was in a pretty difficult program/school) and then it never came back no matter how lazy I got. I also have PTSD from my childhood so I'm sure that relates since I burned out right after I got away from my mom. And I also have had some problems with depersonalization/derealization which is kind of like when your body gets so overwhelmed by stress that it shuts down. However in my case I'm not sure if PTSD is the ultimate cause of all of this stuff or not. I also am not sure if it's related to my exercise intolerance or if they're separate issues.

cwolfman13 wrote: »

I think the illnesses are likely more a coincidence rather than caused by exercise. This is the worst flu season in decades and we have RSV and COVID on top of that. Almost everyone I know personally has had a pretty bad bout of illness or and/or multiple raspatory viral infections at some point this winter.

I think I would have gotten the illnesses either way but I don't know if they would have been as bad without the working out component. My partner got the same illnesses as me and recovered much more quickly and didn't have as bad symptoms. Also I got RSV in October before I began working out and it was more of an annoyance than anything else. And there's no way it can be the worst flu season in decades because H1N1 happened in 2009-11.

As your exercise goes, you may think you're taking it slow, but it doesn't actually appear that way to me. The higher intensity of work you do, the more rest and recovery you need, especially when you're at a relatively low level of fitness. For running I would recommend following a structured running program like C25K...they are typically 8-9 weeks and will build you up slowly. Going from walking to jogging a mile in a week is a pretty rapid progression...it isn't slow. A C25K program will at least get you jogging for 30 minutes straight, but in my experience it wasn't a complete 5K...it took me many more weeks to get my actual 5K time down to 30 minutes.

For the gym I would also recommend a structured program. Following structured training beginner programs will help you progress your fitness at an appropriate rate and will minimize the risk of over training, subscribe rest and recovery, etc. Most of what you describe looks like classic overtraining for your current fitness level, not exercise intolerance.

Really? That surprises me because I didn't think I was overtraining. I didn't feel overly tired after working out or anything which I have in the past. Also when I was on the track team in high school they would take people who had never run before and have them doing a 5K (slowly, but even so) in the first week. So I actually felt like my workout regimen was kind of a middle finger to the intensity of the track team which ruined running for me for many years.

hopebewild

If you had a poor VO2 as a kid, there is a good chance you have an underlying respiratory or cardiac issue. Only a Doctor can tell you for sure.