Vous êtes plus fort en fin de journée

The best time for power training is around six o’clock in the evening, according to a study done at the French Laboratoire INSERM. According to the research, published four years ago in Chronobiology, your muscles are at their strongest early in the evening.

The researchers’ findings were not completely new. In 1992 British sports scientists reported that test subjects were capable of running up stairs the fastest and jumping the furthest just after six in the evening. [J Sports Med Phys Fitness. 1992 Dec;32(4):343-7.] What was new in the French study was that the researchers distinguished between the dominant and non-dominant muscles. They first got their ten healthy male test subjects to play football and watched which leg they used to kick the ball away automatically. They labelled the muscles in that leg 'dominant'.

The researchers then determined the maximal power of the test subjects’ quadriceps on a dynamometer: a leg extension machine fitted with measuring equipment. The researchers measured the left and right quads separately at 06:00, 14:00, 18:00 and 22:00 hours. It made no difference what time the researchers took their

measurements – the muscles in the dominant leg were always stronger. D = dominant; ND = non-dominant.

The average maximal strength the subjects were capable of developing fluctuated throughout the day. See below. The black squares represent the average strength of the dominant and non-dominant muscles. At six o’clock in the morning the muscles are at their weakest, and at six o’clock in the evening they are at their strongest. Dominant and non-dominant muscles fluctuate by the same amount.

The researchers also recorded the strength of the nerve signals to the muscles. They found no effect that explained why the test subjects were stronger at six o’clock in the evening. They did notice a relationship with body temperature though. The fluctuations in body temperature were similar to the maximal strength fluctuations.

Body temperature is highest at four o’clock in the afternoon. That means that the body’s metabolism is highest at that time. A little later the muscles are at their strongest. The researchers think that the increased metabolism causes the muscle cells to perform at their best.

There are more arguments in support of early evening being the best time for strength training. This is the time when the relationship between the anabolic hormone testosterone and the catabolic hormone cortisol is at its most favourable. That means that your muscles recover more quickly after the training session and therefore grow better.

Source: Chronobiol Int. 2005;22(3):541-58.

Source: http://www.ergo-log.com/evening.html