It seems counterintuitive, but it’s true: Training is destructive; rest is constructive.
If you’re not getting enough rest — especially in the form of proper sleep — you’re always tearing down and never building up. It is during deep sleep that our bodies repair the damage we’ve done to muscle during intense exercise. And it is during sleep that our bodies build new muscle tissue to better meet the physical challenges that tomorrow will bring.
Without proper sleep, a cascade of negative outcomes manifests itself. Some are obvious. Your workout performance and productivity decline. Your ability to concentrate and focus suffers. Your energy levels plummet.
Other outcomes are less apparent, but equally devastating in terms of physique. At the most basic cellular level, it is during optimal sleep that our bodies repair the cellular mitochondria that are responsible for creating the energy the muscle requires during exercise. Our bodies also continue to digest the carbohydrates that we consumed during the day, converting this nutrition into glycogen during the night. Glycogen is the fuel utilized to generate muscle contractions, and is highly efficient at storing water, which in turn increases muscle size and force potential.
In terms of basic muscle repair and growth, research shows that even a few nights of insufficient sleep is enough to impair the muscle protein synthesis response to nutrient intake (1 Saner, et al). So if you're not getting proper rest, you're putting in the work (training and nutrition) and getting, at best, reduced benefit.
Periods of deep sleep are also critical intervals for hormone production related to muscle growth. Testosterone, which is closely linked to many aspects of overall male health including lower body fat and higher muscle mass, is released during sleep and tends to peak just as we are waking in the morning.
Similarly, human growth hormone is produced during stage three of non-rapid eye movement or dreamless sleep and helps to repair tissues damaged during exercise. The more deep sleep you get, the better the opportunity for muscle tissue to regenerate and grow.
Negative hormonal outcomes can appear as well during poor or insufficient sleep. Lost sleep is associated with elevated levels of cortisol during the afternoon and the evening. Elevated cortisol shuts off growth pathways including insulin release and inhibits testosterone release. Impaired insulin response is another factor in reduced nutrient uptake, leaving muscle tissue to slip into a catabolic state overnight. Elevated cortisol is also often associated with increases in overall excess body fat.
Peak wellness is the indispensable foundation upon which peak muscle growth rests. Peak wellness and restorative sleep go hand in hand.
It is during sleep hours that your body performs cellular clean-up, removing metabolic wastes and toxins, and also establishing and restoring proper blood flow to cells. Proper immune function, which protects us from illness and disease, is also supported by quality rest.
Good sleep is the product of healthy habits. If your social life or screen time is causing you to keep late or irregular hours, then you're not prioritizing your physique goals.
Keep regular bedtime hours and stick to them. Keep your sleep area dark, cool and free of distractions. Avoid stimulants or alcohol, particularly in the hours just before bedtime. If you find that sleep is eluding you, don't just stare at the ceiling. Keep a book on your bedside table and reset by reading for twenty minutes, then turning out the light again.
Modern life is not always conducive to proper sleep. Indeed, we live amidst an epidemic of poor and irregular sleep. But successful people in every field of endeavor, athletes in particular, make a point of getting seven to nine hours of restful sleep a night. You should too.
1 Nicholas J. Saner, Matthew J.-C. Lee, Nathan W. Pitchford, Jujiao Kuang, Gregory D. Roach, Andrew Garnham, Tanner Stokes, Stuart M. Phillips, David J. Bishop, Jonathan D. Bartlett. The effect of sleep restriction, with or without high-intensity interval exercise, on myofibrillar protein synthesis in healthy young men. Journal of Physiology, 11 March 2020.
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