ABSTRACT
Unique to the female athlete is the exposure to rhythmic variations in endogenous hormones during the menstrual cycle (Figure 24.1). The textbook length of the menstrual cycle is 28 days. However, the ‘normal’ menstrual cycle length varies greatly between women from 22 to 36 days between the ages of 20 and 40 years (Vollman, 1977). The cycle is typically divided into three phases, the menses phase, the follicular phase and the luteal phase, during which the levels of gonadotrophins vary considerably. This variation in menstrual cycle hormones and affect on performance has been extensively studied (Burrows et al., 2002; Sunderland and Nevill, 2003; Bambaeichi et al., 2004; Burrows and Bird, 2004), however there is no universal agreement as to the hormonal effects, so precaution needs to be exercised; with hormonal levels and menstrual phases classified and identified prior to, and during, testing of the female athlete. Such classification is essential to ensure that any significant differences found in testing are down to the intervention, and not the variations in hormonal levels at the time of testing. Suitable methods to classify the menstrual cycle phases have been discussed in the literature, of which the main ones are outlined below.
