Some injuries are of course caused by unintended actions and accidents, but others are a direct consequence of the body not being prepared for the tasks undertake. Warming up prior t0 strenous activity is therefore an important if injury is to be avoided
A basic warm-up should incorporate a set of exercises undertaken immediately prior to strenuous activity that act as a period of adjustment for the body. The exercises should be designed to enhance performance and reduce the chance of physical injury, and also preparing a dancer mentally.
Beneficial effects include:
- time to focus on the performance to follow;
- increased elasticity of muscles and tendons. Muscle elasticity is dependent upon blood saturation, so cold muscles with a low blood saturation are more susceptible to injury;
- faster and deeper breathing that allows more oxygen to be inhaled, and more carbon dioxide to be exhaled;
- a rise in internal body temperature, dilating skin capillaries and start sweating as the intensity of exercise increases;
- a rise in the heart rate that encourages the absorbtion of more oxygen and glucose by the muscles;
- increased range of joint movement;
- more efficient transmission of signals along motor nerves that allows quicker and smoother muscle contractions and hence enhanced co-ordination;
- improved proprioception - a greater awareness of joint and muscle positions and movements due to improved transmission of sensory-nerve feedback;
- change from parasympathetic to sympathetic control of the autonomic nervous system;
- redistribution of blood as it is diverted into muscles and skin; and
- release of energy fuel stored in the body - ie the conversion of glycogen to glucose by the hormone glucagon.
Warming-up is necessary regardless of the ambient temperature. It should ideally include the following:
- gentle stretches to the large muscle groups, holding each one for 10-15 seconds;
- balance exercises, such as standing on one leg, then controlling the bending and straighteningof the supporting leg - perhaps rising on to demi-pointe; and
- rhythmic activity such skipping and those involving the joints of the body, such as moderate arm swings, knee bends, sways and trunk rotation. Such exercises should not initially reach end-of-range movement.
The duration of a warm-up takes inevitably depends upon the age and fitness level of a dancer. A childmight be exhausted after jumping around for more than a couple of minutes, but a full-time student might typically need 10-15 minutes to fully warm up. The fitter a dancer is, and the more often they train, the longer a warm-up should be to have beneficial effects. A warm-up should be a compromise - sufficient to increase muscle and core temperature without causing significant fatigue or energy reduction, and should not involve much in the way of technical demands.
