Warming up before strength training is not necessary

You can skip warming up before strength training

10 - 20 minutes of warming up before strength training is still part of the routine for many people who train. Find out in this blog why you can save this time.

Thermoregulation

Humans are homoiothermic (warm-blooded) organisms, whose temperature is kept constant even when the ambient temperature changes. However, this only applies to the body cavities (core temperature approx. 37 °C). Limbs and skin behave almost poikilothermically (cold-blooded). The task of thermoregulation is to keep the core temperature constant at a set point. On average this is 37 °C and it is subject to daily fluctuations of approx. 0.6 °C. If the core temperature rises above the set point (e.g. during physical work), the internal heat flow is increased by dilation of the skin vessels. Secondly, sweat secretion increases, which cools the skin surface and thus creates the core-to-skin temperature gradient needed for the internal heat flow. Keeping the core temperature constant is therefore only possible by balancing heat production plus heat uptake with heat release.

Heat production

Heat production depends on energy expenditure. At rest, the internal organs contribute approx. 56 % to heat generation, and muscles and skin approx. 18 %. During physical work, heat generation increases several times over, and the share of the muscles can grow to approx. 90 % of heat generation in the body (Silbernagel and Despopoulos 2003). Heat production depends on body mass. The greater the body mass, the faster the temperature rises during activity. That women generally feel cold faster than men is therefore due to their slightly lower muscle mass.

Heat release

Heat release involves thermal radiation, heat conduction from the skin to the surrounding air and, as already discussed, the evaporation of sweat droplets. A prerequisite for heat release through evaporation is that the ambient air is relatively dry (e.g. sauna).

If the body temperature falls below the set point, not only is heat release reduced, but heat production is also increased through voluntary muscle movements and muscle shivering. Infants can additionally produce "shivering-free" heat in brown adipose tissue.

Research shows that the speed of enzymatic reactions doubles for every ten degrees of temperature increase. A slight increase in body warmth has a beneficial effect on short-term performance. However, this sets in very quickly, during strength training for the muscle being trained within a few seconds (that is, during the first few repetitions, when the weight still seems "light"). From about 39 °C, the use of oxygen in the muscle deteriorates drastically, which leads to rapid fatigue. If the muscle temperature rises above 43 °C - only 6 degrees above normal temperature - the muscle protein coagulates and death occurs immediately.

The benefit of warming up before strength training

Warming up before strength training in the sense of a non-specific rise in muscle temperature therefore brings no additional benefit. The risk of muscle injuries therefore depends less on the temperature state of the relevant muscles than on the "explosiveness" of the movement. Such fast, jerky movements lead to load peaks that can exceed the breaking load of the tissues involved (tendons, ligaments, cartilage, bones, muscles). Movements during strength training should be performed slowly and under control.

Warming up before sporting competitions

The situation is different with the so-called warm-up or warming up before sporting competitions. Its purpose is to retrieve the kinesthetic images through preparatory movements before complex movement tasks, above all by visualising the competition situation. It is also known that muscle contractions have a reflexive effect on mood. Thus, warming up serves above all as a neurophysiological and mental preparation and is highly valued.

Warming up before endurance training

Warming up and cool-down are important in endurance training. However, here too the "warm-up" does not primarily serve to raise the temperature in the muscle. Rather, it serves to minimise the so-called oxygen deficit. While performance in endurance training adjusts to the required level within seconds (e.g. "level 6", 100 W, "L5" etc.), oxygen uptake rises more slowly, and a balance is only reached after 2 - 3 min (adjustment of oxygen uptake to the performance). Oxygen uptake therefore lags behind energy demand, which is initially covered from other energy stores; an "oxygen deficit" thus arises at the start of the work. Therefore, performance at the beginning of endurance training should be increased slowly in small steps ("warm-up").

Source: Silbernagel J. and Despopoulos A. (2003): Taschenatlas der Physiologie, 5th edition (Georg Thieme Verlag, Stuttgart New York).