Hair grows in a repeating cycle of three phases called anagen, catagen and telogen that is not affected by sweat, according to HairlossHelp. Growth of the hair shaft happens only during the first phase when the shaft grows half an inch each month for two to eight years.
During the second phase of hair growth, the shaft stops growing. The follicle, which is the bulb from which the shaft grows, shrinks for two to four weeks. The final phase is a resting period lasting from two to four months. After this resting period the old hair shaft is pushed out, and growth of a new shaft begins.