FEMALE ACCELERATION TOLERANCE - EFFECTS OF MENSTRUAL STATE AND PHYSICAL CONDITION

Introduction: The literature contains a paucity of information on fema le tolerance to high sustained acceleration. With women now flying hig h-performance aircraft, gender-specific factors that may affect female acceleration tolerance have become increasingly important. The purpos e of this investigation was to determine how menstrual state and physi cal condition affect acceleration tolerance. We hypothesized the menst rual cycle would have no effect on acceleration tolerance and that a p ositive correlation would exist between physical fitness level and tol erance to high sustained acceleration. Methods: Centrifuge exposures o n 8 female subjects consisted of a relaxed gradual-onset run (0.1 G.s( -1)) to the visual endpoint, a rapid-onset run (6 G.s(-1)) to +5 Gz fo r 15 s, and a +4.5 to +7 Ct simulated aerial combat maneuver (SACM) to physical exhaustion. Acceleration tolerance data were collected at on set of menstruation and 1, 2 and 3 weeks following the onset for two c omplete menstrual cycles. On separate days, body composition, anaerobi c power output and peak oxygen uptake were determined. Retrospective d ata from 10 male subjects who had performed the +4.5 to +7 Ct SACM wer e analyzed and compared to these data. Results: Analysis of variance r evealed no significant difference in relaxed tolerance or SACM duratio n between the four selected menstrual cycle time points. Time-to-fatig ue on the +4.5 to +7 Ct SACM was positively (p less than or equal to 0 .05) correlated with absolute fat-free mass (r = 0.87) and anaerobic p ower production (r = 0.76) in female subjects. However, when these var iables were adjusted for total body mass, the significant correlations no longer existed. No correlation was found between SACM duration and absolute (L.min(-1)) nor relative (ml.kg(-1).min(-1)) aerobic fitness . Time-to-fatigue during the SACM was not significantly different betw een male and female subjects (250 +/- 97 and 246 +/- 149 s, respective ly).