Figure 2. Subjective stress associated with running. Subjects were asked to evaluate the stress associated with running on a scale from 0 to 10, with 10 being maximal. The means + standard errors are shown. The number of subjects in each group is shown in the bar. MDR – middle distance runners (15-30 miles per week) with regular menses; LDR – long distance runners (>30 miles per week) with regular menses; AR = amenorrheic runners. Stress was significantly greater (p<0.001) in both long distance and amenorrheic runners compared to middle distance runners. (Data from Schwartz et al., reference 103).