Acute Effect Of Knee Extension Exercise Protocol On Muscle Localized Phase Angle Among Young Women

The raw parameters obtained through localized muscle bioimpedance analysis (ML-BIA) have proven to be sensitive in identifying muscle injuries and appear to be adjustable through physical training in athletes. PURPOSE: To assess the acute effect of a multiple-set knee extension exercise protocol in ML-BIA parameters of the quadriceps muscle. METHODS: 28 young women (21.6 ± 2.7 yrs) performed a maximal multiple series protocol on the leg extension machine with five sets and a 90-second rest on the right leg. The load was calculated from 70% of the one-repetition maximum test (1RM). ML-BIA was performed on the anterior right thigh before, immediately after, 5-, 10-, and 15-minute post-exercise. Participants were lying in the supine position using a tetrapolar 50khz device. Electrodes were positioned 5 and 10 cm distally from the anterior-inferior iliac spine and 5 cm above the superior pole of the patella. The parameters of resistance and reactance were adjusted by the segment length in meters, and the localized phase angle (ML-PhA) was subsequently calculated. Mixed ANOVA was used to compare the right and left legs across different moments. Pairwise comparisons were conducted using the Bonferroni. RESULTS: Compared to baseline the ML-PhA of the right quadriceps showed an increase in the post-exercise (p = 0.026), while decreasing in the 5-min (p < 0.01), 10-min (p = 0.001), and 15-min (p < 0.01). There were no significant differences between moments for the left quadriceps. As expected, the left quadriceps showed higher ML-PhA values compared with the right quadriceps at 5-min (p = 0.028), 10-min (p = 0.001), and 15-min (p < 0.01) post-exercise. CONCLUSION: ML-PhA seems to be sensitive to a knee-extension exercise protocol among young women and PhA change seems to stabilize after 15 minutes of rest. The ML-PhA was demonstrated to be a practical tool to monitor muscle tissue damage from localized fluid accumulation and could help to determine healing for return to physical activity.