Concentric and eccentric isokinetic measurements in knee muscles during the menstrual cycle: a special reference to reciprocal moment ratios.

OBJECTIVE

To investigate the effects of menstrual cycle on the reliability of concentric (CON) and eccentric (ECC) isokinetic measurements and reciprocal moment ratios in knee muscles.

DESIGN

Repeated measurements.

SETTING

A university exercise physiology laboratory.

PARTICIPANTS

Sixteen healthy sedentary women volunteers, aged 24 to 35 years, who had regular menstrual cycle (ranging from 24 to 32 days).

METHODS

Subjects were tested at 60 degrees/sec (4 repetitions) and 180 degrees/sec (20 repetitions) of angular velocities for CON and ECC tests at the menstrual (MP, days 1 to 3), follicular (FP, days 7 to 10), and luteal phases (LP, 19 to 21). Blood samples were analyzed for sex hormones at the FP and LP.

RESULTS

ECC and CON peak torques and total works, and their reciprocal ratios in dominant knee muscles, were not significantly different among the phases by ANOVA. Intraclass correlation coefficients (ICCs) among the phases for peak torque and total work of knee extensors in both angular velocities were in the range of .68 to .91 and .45 to .84 for CON and ECC tests, respectively. However, it was in the range of .03 to .72 and .65 to .94 for CON and ECC tests of knee flexors, respectively. In addition, there were no significant correlations between sex hormones and tested variables.

CONCLUSION

The results suggest that the phase of the menstrual cycle should not be taken into account in isokinetic measurements.