Some coaches advise mandatory rest days, others — daily movement as the basis of health. Who is right? The answer depends on what exactly is meant by «training»: a daily walk and a daily squat with maximum weight are completely different things. The editorial team breaks down what physiology and studies of training frequency say.
Where the myth of mandatory rest came from
The notion that muscles need 48–72 hours «to recover» and that training every day is harmful comes from entirely real observations. After a heavy unaccustomed load the muscles ache for several days, and strength temporarily decreases. It is logical to assume that training in such a state will only do harm.
The classic split programs of bodybuilders — «chest on Monday, back on Tuesday» — were built precisely on the idea that each muscle group needs a week of rest. At the same time the athletes themselves trained 5–6 days a week, simply distributing the load among different parts of the body.
On the other hand, the recommendations of the WHO and medical organizations call for physical activity every day or almost every day. Regular walking, cycling, swimming are useful for health — and no one considers a daily walk dangerous.
The contradiction disappears if the concepts are separated. Daily movement of moderate intensity is safe and useful. Daily maximally heavy training of one and the same muscle group is another story, where recovery really may not keep up. Between these poles there is a large space for reasonable planning.
How muscles, the nervous system and tendons recover
After strength training muscle protein synthesis rises and stays elevated for about 24–48 hours in untrained people; in trained people this period of elevated synthesis is shorter. That is exactly why many specialists consider it advisable to train each muscle group at least twice a week.
Delayed onset muscle soreness (DOMS) is strongest 24–72 hours after an unaccustomed, especially eccentric, load. But soreness is not an exact indicator of recovery: with adaptation to the exercises it almost disappears, although the muscles receive a stimulus for growth. Orienting only on soreness when planning training is incorrect.
Different systems recover at different speeds. Energy stores (glycogen) with normal nutrition are replenished over the course of a day. Muscle fibers after a moderate load — in 1–2 days. Connective tissue — tendons, ligaments — adapts more slowly, and it is exactly here that overload injuries often arise with a sharp increase in volume.
The nervous system also needs recovery after maximal efforts — attempts at a repeat maximum, sprints, jumps. Training «to failure» in every set every day creates a significantly greater load than working with a reserve of a few repetitions.
What studies of training frequency say
The meta-analysis by Schoenfeld and co-authors (2016) showed that training each muscle group twice a week gives a greater gain in muscle mass than once a week. A later meta-analysis by the same group (2019) clarified: with the same total weekly volume, frequency by itself does not significantly affect hypertrophy — the total volume is more important.
Practically this means that the same volume can be distributed over 3 or over 6 workouts — and the result will be similar. For someone 6 shorter sessions are more convenient and easier to tolerate than 3 long ones. So daily training is not harmful in itself if the weekly volume is adequate.
As for strength, studies of frequency have similar conclusions: with equal volume the difference is small, although more frequent practice of an exercise can improve technique. It is no coincidence that high-level weightlifters train practically every day, and sometimes twice a day — under a coach's supervision and with careful periodization.
In runners and other endurance athletes daily training is the norm. But the greater part of their volume is performed at low intensity, while heavy interval sessions take up only 1–3 days a week. So-called «polarized» training is another example of the fact that frequency is possible when intensity is distributed correctly.
| Type of activity | Safe every day? | Conditions |
|---|---|---|
| Walking, light cardio, mobility | Yes | For most people without restrictions |
| Strength, different muscle groups | Yes | Reasonable weekly volume, sleep and nutrition |
| Strength, the same groups to failure | Risky | Only with experience and periodization |
| Interval, high-intensity | Mostly no | Usually 1–3 times a week |
When daily training really is harmful
Problems arise when the load for a long time exceeds the capacity for recovery. The first stage is functional overreaching: a temporary decrease in results, which passes after a few days of rest. If the load is not reduced, non-functional overreaching may develop, and in the extreme case — overtraining syndrome, recovery from which takes weeks or months (Meeusen et al., 2013).
- a persistent decrease in results despite training;
- constant fatigue, heaviness in the muscles, «cotton-wool» legs;
- sleep disturbances, an elevated resting pulse, irritability;
- frequent colds, slow healing of minor injuries;
- decreased appetite and libido, loss of motivation.
The risk grows when several factors act at the same time: high volume and intensity, sleep deprivation, calorie deficit, work stress. Training every day against a background of a harsh diet and 5-hour sleep is a typical scenario in which the body «breaks down».
A separate risk group is beginners who, after a long break, immediately take up daily intense training. The connective tissue and muscles are not yet adapted, and a sharp increase in load raises the risk of tendinopathies, stress fractures and even rhabdomyolysis — severe muscle damage with a risk to the kidneys.
Finally, it is worth remembering the psychological aspect. The strict rule «no skipping» can turn into compulsive behavior, when training is continued despite injuries and illness. This is no longer about health.
How to organize daily training wisely
The first principle is alternating the load. You can distribute strength training by muscle groups (upper/lower, push/pull/legs) or alternate heavy, medium and light days. This way each system gets rest, although you train every day.
The second is control of weekly volume and intensity. Most sets should be performed with a reserve of 1–3 repetitions to failure; true failure is a tool that is used in measured doses. For cardio the main part of the volume is low intensity, when you can talk.
The third is active recovery days. A walk, light swimming, mobility or yoga is also «training» that maintains the habit and blood circulation without creating significant stress. For many people it is exactly this approach that makes daily movement a sustainable habit.
The fourth is the basic recovery factors: 7–9 hours of sleep, sufficient energy and protein (for people who train, roughly 1.4–2.0 g/kg of body weight per day according to the ISSN position), regular deload weeks. It is useful to keep a journal of training and well-being in order to notice a trend toward fatigue in time.
And the fifth is to heed the body's signals. Pain in a joint or tendon that intensifies, an illness with fever, pronounced fatigue are a reason to take a pause. Training «through force» in such states does not speed up progress.
Editorial conclusions
Training every day is not harmful if you understand what exactly you are doing every day. Daily moderate movement is useful, and strength training can be done frequently provided the load is distributed and the weekly volume is adequate.
Harm is caused not by frequency as such, but by the combination of high intensity, large volume and lack of recovery — sleep, food, rest.
The best plan is the one you can follow for years without injuries and burnout.
Read also: «Can You Get Abs in a Month», «Stress and Libido» and «Is It True That Muscle Turns Into Fat».
References
- Schoenfeld BJ, Ogborn D, Krieger JW. Effects of resistance training frequency on measures of muscle hypertrophy: a systematic review and meta-analysis. Sports Med. 2016;46(11):1689–1697.
- Schoenfeld BJ, Grgic J, Krieger J. How many times per week should a muscle be trained to maximize muscle hypertrophy? A systematic review and meta-analysis of studies examining the effects of resistance training frequency. J Sports Sci. 2019;37(11):1286–1295.
- Meeusen R, Duclos M, Foster C, et al. Prevention, diagnosis, and treatment of the overtraining syndrome: joint consensus statement of the ECSS and ACSM. Med Sci Sports Exerc. 2013;45(1):186–205.
- Bull FC, Al-Ansari SS, Biddle S, et al. World Health Organization 2020 guidelines on physical activity and sedentary behaviour. Br J Sports Med. 2020;54(24):1451–1462.
- Jäger R, Kerksick CM, Campbell BI, et al. International Society of Sports Nutrition position stand: protein and exercise. J Int Soc Sports Nutr. 2017;14:20.
- Seiler S. What is best practice for training intensity and duration distribution in endurance athletes? Int J Sports Physiol Perform. 2010;5(3):276–291.
Andriy Melnyk
A strength-sports coach and author of programs for beginner and intermediate levels. Writes about training planning.
