(2/) To begin, there are a few times in exercise physiology (& other domains, I’m sure) where you hear about a “J-Curve” model.
Exercise & immune function is a classic J-Curve: Too little = bad, too much = bad, but in between = lower infection risk. Fitness is a health benefit
Exercise & immune function is a classic J-Curve: Too little = bad, too much = bad, but in between = lower infection risk. Fitness is a health benefit
(3/) Then you have the “Open Window hypothesis”, which is to the J-curve what Bonnie was to Clyde. Idea is that there’s a window after intense and/or prolonged exercise where you’re more vulnerable to infection. Diagram shows changes from hard (marathon) & easy (walk) exercise
(4/) In this model, intense/long exercise negatively affects innate & adaptive immune function, & causes inflammation. None of this happens for walking. Result is a shift to an anti-inflammatory state, which impairs immune response to new pathogen. Hence = a vulnerable “window”.
(5/) This is not entirely cut-&-dried. Some debate that it may not be exercise per se, but other risk factors that exercise brings, increasing risk. So a confounder is that races & training etc involve crowds, public spaces, travel, lack of sleep, anxiety etc which increase risk
(6/) For instance, gyms are spaces that involve exactly the opposite of social distancing (which we all know & hate now!), plus equipment with bugs and touching etc. So people who do a lot of training often may increase infection risk in 2 ways - exposure & impaired immunity
(7/) The reason this matters in this time is because you may need to reassess what you’re doing in training. Optimize health, not performance. And if you do train intensely & hard, take precautions that help your immune system deal with risk. Now is not a good time to get sick!
(8/) Of course, if you’re in lockdown, you’re in forced social distancing, so the “exposure” risk is minimised. But still, rather be healthy & reduce the focus on the performance sessions. And remember diet & sleep - your immune system’s enablers (not a great time for big diets)
(9/) Next, let’s talk detraining. You’re in lockdown, cut off from normal training facilities & routines. Maybe you can’t even go outside. Hugely frustrating (I know!). Unfortunately, the “use it or lose it” principle is in play here. Gains are reversible. But good news awaits!
(10/) First, goal-setting. You have a spectrum of options. You could do anything from “nothing”, to running marathons in your house. I wouldn’t advise either - exercise is healthy, as we’ve seen, but too much, right now, in that context, may be damaging too. So it’s about balance
(11/) To understand reversibility (“use it or lose it”), let’s look at 2 study examples. First, this one in German put healthy men in strict bed-rest for 2 months (yikes!), and measure a bunch of changes. None of them are good or healthy! From bone to cardio, we “decline"
(12/) Same in this one, looking at top level cyclists who stopped totally for 4 wks. Mass & skinfolds go up (though not sig.), and VO2max & performance down. Not a surprise. About 2-3% per week is the norm for these changes. You also get decrease plasma volume, enzymes etc
(13/) But here’s the good news. A study in elite kayakers, some of whom rest totally for 5 wks, some who do 3 sessions per week. Normal training is ± 10hrs/wk, so we’re looking at 0% or 20% of normal. See how even 20% cuts losses in half? Key point - a little goes a long way
(14/) Same thing here in healthy men, not elite athletes. This is the bed rest study from earlier. Some of the men did 3 min a day of hopping & CMJ. *3 min a day!* Crazy how little it is. But look at the effect - reduce loss of bone, lean mass, strength, VO2max & power. Crazy! 😳
(15/) What about strength? Same - here’s that kayaking study. Remember, some did 0% of normal for 5wks, others did ONE basic 40 min strength session per week (normal was 3 sessions, 3hrs). Same thing - see how the drop in bench press & pull are cut in half by that one session?
(16/) But now you’re wondering what happens on the other side? When you restart, after #lockdown, what can you expect? Here are two studies, showing both detraining and REtraining. In Henwood et al, detraining caused 16.5% loss of strength in 24 weeks. Within 12 weeks, it’s back
(17/) And then on the right, Blocquiaux study found that men gained 36% in 12 wks, then lost 14% with 12 wks of detraining (lockdown-like!), and then gain back 24% in 12 wks. Losses are recovered within 6 weeks of resuming. This is great news - easy go, easy come, you might say!
(18/) So let’s sum up strength training. Detraining causes losses, but they can be recovered. You may be denied access to heavy weights during #lockdown. But use volume & train to fatigue to compensate, because training to failure drives hypertrophy (& some strength gains)
(19/) Then when it’s time to return, you’ll be in a position to get back to the peak as soon as possible. That depends on many factors, but what you do NOW predicts your future! Here’s another study (Staron et al) showing that can regain the loss, so don’t despair - invest now!
(20/) And finally, a summary. Be careful with some of this stuff - plyometrics like hopping and drop jumps etc are effective, but risky! So too, new loading can be injurious. So go carefully! But go with confidence. Every little bit matters, small investments are not wasted!
(21) And finally, finally, it is frustrating, I know. But it’s also an opportunity. A chance to do things your body may NEED (like rest! And strength work. Stability. Core) as opposed to the things you like. If you nail this, the negative effect will be small, positive HUGE!
(22/) And that’s my bit, a tweetorial on immune function, exercise & detraining. This is the summary - if you fancy the “full meal”, you can watch it here: Please share, and then stay healthy, sane and motivated! (/end)
