What is the best time of the day to exercise for muscle growth

We often ask ourselves whether there is a right time to train during the day. The answer is yes: find out when and why.

Some of us like to exercise in the morning before work to start the day full of energy and have more free time at the end of the day for family, social life or other passions. Others prefer to train on their lunch break to break up the day. Many, on the other hand, go to the gym in the evening at the end of the workday to relieve stress and be able to work out in peace without time constraints.

Have you ever asked yourself what is the best time to train to get the results you want?

There are scientific answers to this question. Depending on the training goal, there is a time of day when it is preferable to train for best results.

You have certainly heard of the 'biological clock', but what you may not know is that the cycle that regulates your body is not just your life cycle. Chronobiology has a seasonal (circannual), monthly (circamencial), lunar (circalunar) and DAILY (circadian) rhythm!

The circadian rhythm: temperature and testosterone

The circadian rhythm - which is 24 hours long and regulates the body's functions according to the hours of the day and night - predicts changes in body temperature and hormone levels throughout the day.

Physiologically, your temperature has a minimum peak around 6 a.m. and a maximum peak towards evening, between 5 p.m. and 8 p.m. A higher body temperature (mind you, we’re not talking about a having fever!!) actually coincides with a more effective use of carbohydrates as an energy source and more effective muscle contractility.

From a physiological point of view, each hormone also has a maximum peak and a minimum peak, with one or more increasing or decreasing phases.

In this context, it is useful to distinguish between catabolic hormones, which are suited to breaking down (providing simple substances and producing energy) and anabolic hormones, which are suited to construction. Among the various anabolic hormones, when it comes to muscle growth, testosterone and GH stand out.

Testosterone, in fact, also has the ability to stimulate protein synthesis in the muscle system and thus stimulate muscle mass growth.

Physiologically, blood levels of testosterone show:

• a peak maximum in the very early hours of the morning;
• a gradual daily decrease;
• a secondary peak in the early afternoon;
• a minimum peak around 6 p.m.

(The afternoon peak of testosterone is not so precise; the rhythm of testosterone is a function of the performance of other primary metabolic axes.)

In contrast, GH, also known as growth hormone, has among its functions that of ensuring muscle (and bone) trophism in adults.

GH secretion, which is also pulsatile, is highest during the night and in the early hours of sleep: to take full advantage of its effect in promoting muscle mass development, it is ideal to make the early hours of sleep coincide with 11pm/12am.

 

Training and hormonal stimulation

On the other hand, you should bear in mind that it’s not only hormones that influence training – training also influences hormone production. For example, at the beginning of the workout the production of anabolic hormones is stimulated, while continuing the workout beyond 45/60' stimulates the production of catabolic hormones, such as cortisol. Among others, exercise also stimulates the synthesis of adrenaline.

 

So what is the best time to exercise?

If your goal is to develop muscle mass, and if your lifestyle allows you to do so, train around mid-afternoon to take advantage of a spike in testosterone, of the gradual rise in body temperature and to allow you to end the day in the proper time to be able to fall asleep early (and thus take advantage of the GH spike that in the early hours of sleep promotes muscle development).

If adrenaline and cortisol, produced by training, do not disturb your sleep and your evening routine still allows you to go to bed early, you can also move your workout to around 7pm to take advantage of peak body temperature.

If, on the other hand, you do not have the opportunity to train right now, don’t despair! You can still get results in terms of muscle mass like that:

• do an effective warm-up, to increase your body temperature;
• don’t train for longer than an hour, so as not to stimulate the production of catabolic hormones;
• Give yourself a good night's rest.

Otherwise, if your goal is to slim down and lose weight, early morning is the best time. You will take advantage of the activation given by the cortisol peak (between 6 and 7 am) and growth hormone (GH) not yet too low, which together increase the lipolytic (i.e., "fat burning") effect. An aerobic workout done at this time also allows you to take advantage of the nighttime fast, increasing the stimulus to mobilize fat stores.

Always remember that the uniqueness of each individual cannot be overlooked: you are characterized by your unique genetics and lifestyle, which affect your metabolic response.

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