Acute Changes In Muscle Size Of The Vastus Medialis Oblique Following Resistance Training

Abstract

Resistance training causes a temporary swelling of the muscle that leads to an increase in muscle size. This phenomenon has been studied in the literature, but there is a need for more research studies that compare the acute muscle changes due to fatigue between males and females. PURPOSE: To observe the changes in the cross-sectional area (CSA) of the vastus medialis oblique muscle after resistance training to fatigue and to compare these acute responses between males and females. METHODS: Twenty Males (71.00 ± 2.07 cm, 74.11 ± 9.37 kg, Age 19.85 ± 0.41) and 20 females (63.35 ± 2.99 cm, 60.62 ± 8.92 kg, Age 20.00 ± 0.72). Day one served as a familiarization and was to determine a one repetition max leg extension. Day two Panoramic ultrasound images were taken on the largest circumference of the vastus medialis oblique before and after the participant performed four sets of leg extension to failure at 70% max. Images where then analyzed to measure CSA. A time and sex were compared using a repeated measures ANOVA. RESULTS: The mean and standard deviation of the pre-areas for males and females were 22.97 ± 4.49 vs 14.36 ± 3.22 cm2 respectively, while the post-areas for males and females were 24.47 ± 5.66 vs 15.70 ± 3.51 cm2 respectively. There was no interaction effect (F = 0.04, p = 0.74), males had an overall a larger CSA (F = 41.5, p < 0.001) and the post measurement was larger than the pre for both groups (F = 36.56, p < 0.001). CONCLUSION: Males overall had larger muscle size but both responded similarly with an increase in CSA following an acute bout of resistance training to fatigue.