RECREATIONAL EXERCISE DOES NOT IMPAIR MENSTRUAL CYCLES - A PROSPECTIVE-STUDY

To determine whether recreational levels of training (jogging) will provoke short luteal phase menstrual cycles, a prospective study was conducted. Out of 132 women who initiated this study 57 completed it. These individuals were within normal range of cardiorespiratory fitness for 18-40-year-old women. After a control menstrual cycle (#1) and two additional menstrual cycles (#2 and #3) in which light calesthenics were performed, the subjects were then assigned to run < 10 mi/wk, 10-20 mi/wk or 20-30 mi/wk for either two menstrual cycles (#4 and #5), or four menstrual cycles (#4, #5, #6, #7), followed by a detraining period lasting two menstrual cycles (i.e. #6 and #7 for the 2-month running groups; #8 and #9 for the 4-month running groups). Blood samples were obtained throughout every second menstrual cycle (i.e. cycles #1, #3, #5, #7, #9). Samples were assayed for LH, FSH and P. Body weight and body fat (%) were not altered by training (p > 0.05). Improvements in cardiovascular fitness did occur (p < 0.05). No change in LH attributable to running was found in any of the 6 experimental groups (p > 0.05). In some of the groups quite large changes occurred in FSH (p < 0.05), but there was no discernable pattern of onset of these changes among groups. Some increments in P were found (p < 0.05) but again these were not consistent. Finally, in none of the six groups was an altered menstrual cycle length discernable (p > 0.05), nor was the luteal phase length altered (p > 0.05) by running. Therefore, in gynecologically mature women recreational running of up to 30 miles/week for 4 menstrual cycles has no deleterious effects upon their menstrual cycle.