What Does Muscle Loss Start If You Stop Exercising ?

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Life is extremely uncertain, and sometimes despite of our best efforts, we aren’t able to maintain consistency in our workouts and diet routines. Interruptions in training process because of illness, injury, holidays, or other factors are normal situations among athletes and non-athletes alike.

But what worries even more is the loss of precious gains one has incurred over the months and years, due to the break in training.

Now, taking breaks during the week is part of one’s workout, and is extremely important for recovery. Even a slightly longer break is never an issue, if it refreshes you and makes you come back with full vigour.

However, too long a break and you will end up losing your precious strength & endurance gains. But a common question is ‘what is the minimum period of time, for which one can go off training, without losing muscle mass or endurance gains?

  1. The answer varies from person to person and how intensively he/she has been training. For e.g. studies have shown that, in case of an injury or trauma, if you are on bed rest and totally immobilized, you can start losing muscle mass in as little as 7-10 days.

2. However, for most people such condition is rare. Also, reduction in muscle size doesn’t necessarily means loss in muscle mass. It can be due to decrease in the muscle glycogen stores. And we all know that, glycogen stores water in the muscles. So it’s generally water loss, not muscle loss.

3. When it comes to pro athletes, acc. to a systematic review, strength levels can be maintained for up to 3 weeks of detraining, but decay rates will increase thereafter (i.e. 5-16 weeks). A study, on adolescent athletes also showed that, three weeks of detraining did not affect muscle thickness, strength, or sport performance.

4. Similarly, when it comes to endurance athletes, cardiovascular adaptations regress during periods of exercise reduction or abstinence. In a study, 21 runners completed an 18-wk training program (app. 7 h/wk) culminating in the 2016 Boston Marathon after which total exercise exposure was confined to <2 h/wk (no single session >1 h) for 8 wk. The athletes, went from running 32 miles/week to 3-4 miles/week.

Of course physiological detraining was clearly observed through reduction in cardiac output and exercise performance, but the athletes were still able to maintain a certain conditioning level, as they did not completely stop the training. Had they done so, may be they would have had much greater decline in performance.

5. Also, when we compare endurance and strength losses, losses in endurance is a bit faster. Acc. to a study, endurance performance is decreased by 4-25% during periods of training cessation lasting 3-4 weeks or longer. And if you are a beginner, a 4 week break would be as good as starting from scratch.

But when it comes to non-athletes, or people who aren’t working out more than 5 times/week and at a very high intensity, the period to observe muscle loss is about the same i.e. around 3 weeks.

6. Another factor which plays an important role in muscle loss is Age. Lean muscle mass decreases with age at a rate of 5-8% per decade after 30 years.

A study, examined the effects of age and gender on the strength response to strength training and detraining, in eighteen young (20-30yr) and 23 older (65-75yr) men and women. There were no significant differences in strength gains between men and women in either age group with 9 week of strength training.

However, young men and women experienced an 8+/-2% decline in strength after 31 week of detraining. This decline was significantly less than the 14+/-2% decline in the older men and women.

In a study, in older hypertensive women, it took 3 months to see a decrease in all gains made during the 9 months of training. Another study, found that, 1 month of detraining was enough to totally reverse the beneficial effects of a 6-month strength training program on physical mobility and executive function of older women.

7. Interestingly, some research suggests that the rate of muscle loss after a period of hypertrophy is not linear, but in fact occurs more rapidly during the first couple of weeks of detraining compared to any subsequent weeks of detraining. This two-phase process may reflect an initial period of time in which muscle fibres are atrophying due to complete inactivity (owing to a lack of central motor command) and a subsequent period of time in which muscle fibres are atrophying much more slowly due to reduced activity.

8. A meta-analysis study, assessed the effect of resistance training cessation on strength performance. Results indicated a detrimental effect of resistance training cessation on all components of muscular performance, i.e. force production, muscle strength and power. The effect of resistance training cessation was found to be larger in older people (>65 years old). The effect was also larger in inactive people for maximal force and maximal power when compared with recreational athletes. 

When it comes to maximal strength, it remained unaffected for 28 days of training cessation, post which it started reducing. This strength loss was similar for upper and lower body & for men and women. However, older adults (≥65 year old) lost nearly twice as much strength and younger adults (<65 years old). 

9. Another factor which seem to influence strength loss with detraining is the intensity of workouts. A study, determined the effect of exercise intensity on strength, anaerobic power, and mobility of older men subjected to a 24 week strength training protocol followed by prolonged detraining. Participants were assigned to a control, low intensity training (55% 1RM), or high intensity training (82% 1RM) group. They carried out a 24 week, whole body (10 exercises, two to three sets/exercise) strength training program followed by a 48 week detraining period.

Although low intensity training improved strength (42–66%), anaerobic power (10%), and mobility (5–7%), high intensity training elicited greater gains (63–91% in strength, 17–25% in anaerobic power, 9–14% in mobility). All training induced gains in the low intensity group had been abolished after four to eight months of detraining, whereas in the high intensity group strength and mobility gains were maintained throughout detraining.