Time Course Changes In Size And Echo Intensity Of The Bicep Brachii Following Resistance Training

Abstract

Following resistance training, muscles swell due to a combination of damage and an increased demand for oxygen and substrates. Cross-Sectional Area (CSA), thickness, and echo intensity (EI) are measurements have been used to monitor muscle damage and recovery. Due to the variety in responses to resistance training, this study looks at muscle recovery over time while taking into consideration the differences between males and females. PURPOSE: The purpose of this study is to examine the time course changes in muscle size and EI of the biceps bracii following an acute bout of resistance training and determine the potential differences in response 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). Panoramic ultrasound images were taken on the largest circumference of the bicep bracii and used to determine CSA, Muscle thickness and EI. Day 1: Participants performed four sets to failure at 70% on a bicep curl machine with a 90 second rest between sets. Ultrasounds were done pre and post exercise. Day 2 and 3: Ultrasounds only. RESULTS: LINK Excel.Sheet.12 "D:\\Ultrasound 2020\\abstract data.xlsx" "Sheet1!R2C16:R11C20" \a \f 4 \hMales and females had similar responses over time (P = 0.17-0.96) for each variable. Post exercise values for CSA, thickness, and EI *(p < 0.001) where all large but returned to baseline values by 24 hrs. Males had large muscle size ^(p < 0.001), but not difference in EI (p = 0.769). CONCLUSION: Immediately following resistance training, muscle size and EI are significantly larger for both males and females and returns to baseline in 24 hrs. Males and females exhibit similar patterns; however, males have larger muscle size and but similar EI values.