Inactivity and prolonged bed rest, due to illness or quarantine, will lead to substantial muscle mass atrophy, loss of strength and loss of endurance. Low gravity environments have similar effects but since most of us aren't astronauts, I'll focus on what happens when we are immobile or simply lazy for longer periods. Sometimes there are events in life that are so completely overwhelming you simply have no time to exercise. Many of us will eventually sustain an injury, illness or disease that will force us to take a break. If you are like me, you start to worry if you take more than 3 days off. In 35 years, the longest I've taken off is 6 months. It is a long story involving a temporary job as a delinquent youth camp counselor. Suffice to say I was eventually able to regain my fitness level and more within 3 months. In this post I will review the literature and answer a question I'm sure many of you are asking yourselves: How lazy can I be and still keep my fitness?
If you are bedridden or in the hospital for 10 days or longer expect to lose a significant amount of endurance and strength. The rate of loss has many confounding factors including age, epigenetics, genetics, nutrition, physical therapy, etc.... During hospitalization your muscles will atrophy and bones will become more brittle. Locomotion, balance and respiration will also suffer. Light physical mobilization and electrical muscular stimulation can ameliorate some of these effects. While avoiding these types of hospital stays is a good idea, the choice is rarely ours.
Now let's talk about laziness, minor injures and global pandemics that can keep us out of the gym. The good news is that your losses will not be so rapid or severe as long as you continue to walk around and perform regular activities of daily living. On the other hand, a gold medal winning couch potato will deteriorate at a much quicker pace.
A systematic review by McMaster et al., (2013) reviewed 27 studies examining detraining and how it affects strength on the experienced athlete. Here's what they found:
"Based on the above outcomes and past literature, it can be speculated that maximum strength levels can be maintained for up to 3 weeks without resistance training, but decay rates will increase thereafter (5–16 weeks).”
Another review by Fisher et al., 2013 found:
“Trained persons performing regular resistance training are encouraged to allow adequate rest between training sessions without fear of atrophy. Brief (~3 weeks) absences from training appear not to cause significant atrophy and potentially promote greater hypertrophy upon return to training”
Endurance performance decreases by about 4% to 25% after 3-4 weeks in trained athletes (Bosquet & Mujika, 2012). The research indicates it's best to avoid breaks longer than 2-3 weeks, especially when it comes to cardio training. Quarantined or sheltering in place? You can still jump rope, do mountain climbers, jumping jacks or burpees to get your cardio quota. It doesn't take much to maintain your endurance. When time is a factor high intensity interval training (HIIT) can be a good addition or stop-gap measure, keeping your cardio levels from deteriorating. As long as your downstairs neighbors don't mind, you can also run in place, do squat jumps or other plyometrics.
Interesting evidence suggests strategic de-conditioning [taking planned breaks and performing light movements in periodized workout cycles] can make muscles more sensitive to anabolic signaling [hormonal messages which tell our muscles to adapt]. This may actually be beneficial for long-term gains (Ogasawara et al., 2012; Fisher et al., 2013; Schoenfeld et al., 2014). I personally aim to take a week off, or go high rep low weight, every 12 to 14 weeks. When I do this I come back stronger and better rested. Many competition athletes will take a light taper week or a full week of rest immediately prior to their scheduled competition. This primes their body and mind for peak performance.
An injury is sometimes an opportunity. Did you break your arm or sprain your ankle? Take the opportunity to train areas you've been neglecting. Work on your weaknesses and do something different. Expand your fitness. There is data showing a strong contralateral strength training effect. This counterintuitive phenomenon occurs when you workout one side of the body and the opposite side, that’s doing nothing, reaps some benefits. Meta-analysis shows an individual may gain up to “half the increase of strength of the trained side” in their nonworking side. Working out lightly or in a truncated manner will still create a multitude of systemic bio-psychological benefits.
If you have an acute injury, don't stress about having to take up to 14 days off. Rest and relax if needed. During recovery, be mindful of M.E.A.T. This is a new post-rehab protocol that stands for Movement, Exercise, Analgesic and Treatment.
For those of us who push the limits of our bodies and/or consistently workout hard, take some time off every 3-4 months (stay active though). Let the body fully recover. Enjoy, relax and chill. It will do wonders for your body and brain. I like to call it 'active rest'.
The government imposed quarantines are not a good excuse to forgo all physical activity. If you are simply sequestered and can't go to the gym, there are many exercises you can do in your home without equipment. With a little help from a trainer or an online tutorial, most people can continue an in-home fitness program. Whenever possible, continue to exercise daily. Humans are like sharks: to stay alive, we gotta keep moving.
Summary of the Research:
Detraining - Less than 4 weeks:
*Strength can be maintained without training up to 3-4 weeks but is gradually lost thereafter (strictly speaking, you can temporarily lose strength before this, but it comes back so quickly during retraining that it doesn’t matter).
*Muscles start to atrophy after 2-3 weeks, though gains usually come back quickly, at least for beginners.
*Endurance performance decreases by 4% to 25% after 3 to 4 weeks.
*VO2 max declines by 6 to 20% in highly trained athletes at around 4 weeks of detraining.
Beginners can maintain endurance performance for at least 2 weeks without training, though recent VO2max gains can be reversed after 4 weeks.
*Muscle, strength, endurance, and fat gains/losses vary from person to person. This is due to genetic interindividual variability.
*Muscles seem flat or deflated the first weeks of detraining because muscle glycogen stores shrink, not because you lose mass. Muscles visually become smaller, but only because glycogen binds water. Good news: the effect is temporary since glycogen stores quickly expand when you resume training.
*Flexibility is reduced after 4 weeks of detraining by ~7-30%
*To maintain strength during 4 or more weeks of detraining, train at least 1x per week (for beginners). Trained lifters could maintain strength gains with eccentric training.
*To maintain hypertrophy during 4 or more weeks of detraining, workout at least 1x per week (for beginners). There’s not much long-term data for trained lifters, but eccentric training could help.
*To maintain endurance capacity (cardio) during 4 plus weeks of detraining, you can lower training volume by 60-90%. Total training frequency can be decreased by no more than 20-30% in athletes and by 50-70% in beginners. Training intensity should remain the same.
*It’s easier to regain strength and muscle mass once it’s lost because of myonuclei and neural adaptations, AKA muscle memory.