For example, if the exercising is done with the idea of losing weight in a hurry, one can be very sure of losing hair. The exercise regime triggers a medical condition called Telogen Effluvium. The hair loss happens due to nutritional deficiency which is inevitable with any program associated with quick weight loss, because one can never maintain the right balance of diet and lose weight quickly at the same time.
Similarly certain exercises which aim at increasing the body muscles mass are also liable to cause hair loss due to exercise. Here the causative factor is believed to be protein redistribution, where the body takes protein away from other parts of the body, hair being one such part, and redirects it to building the muscle mass. Even taking protein supplements in such cases, may not help, for the following reason – Proteins are composed of 22 amino acids. Most protein supplements have a good combination of these, but hair needs a specific combination of 4 amino acids and if your protein powder lacks even one of those, then it may help build muscle mass, but will not help in controlling hair loss.
A study showed that strenuous exercises cause an increase in the blood testosterone levels by as much as 30% in some cases. As testosterone is linked to the causation of male baldness, increase in levels would definitely lead to an increase in hair fall and hasten the baldness. The problem however is defining what exactly constitutes strenuous exercises. The study defined strenuous exercises as that which involves lifting heavy weights, or muscle building or any changing in the body structure. More routine exercises like cardio exercises, jogging, running, treadmill exercises which are aimed at just fitness are not included in this category. However the demarcating line is not always very clear.
On the other hand exercises which involve the use of steroids are a definite threat. This is because most steroids resemble in their molecular structure the male hormone testosterone and thus can cause excess hair fall. It is not surprising therefore to see a lot of body builders who use steroids to build their six packs and eight packs often end up balding as well.
Other factors which come into play are increased sweating and sebum secretion on the scalp. Increase in sebum secretion can contribute to more hair loss. Because the scalp sweats a lot while doing even routine exercises, it is important to wash your scalp after the exercises.
The safest forms of exercises are those that are aimed at simple fitness. Exercise should not be done with the idea of losing weight drastically or developing muscles overnight.