Acute and delayed effects of concentric and eccentric exercise on quantitative muscle MRI

摘要

Background Advanced magnetic resonance imaging (MRI) is capable of identifying subtle effects of exercise. However, it is unclear whether it is sensitive enough to differentiate between different contractions. Purpose To compare the acute and delayed effects of concentric and eccentric exercise on quantitative MRI in hamstring muscles. Material and Methods Participants performed eccentric and concentric leg curls. Quantitative T2 and magnetization transfer ratio (MTR) maps were calculated in the hamstring complex before exercise, 30 minutes, 24 hours, 7 days, and 14 days after exercise. Results Compared to baseline, significant MTR reduction (-7.3%) and T2 elevation (72.2%) were observed in the semitendinosus muscle (ST) at 24 hours after eccentric exercise (P = 0.04). Concentric contractions induced T2 elevation in the ST (20.8%) and biceps femoris (5.1%) muscles at 30 minutes after exercise (P = 0.04) which normalized within 24 hours. Conclusions Longitudinal effects of concentric and eccentric exercise can be detected by both T2 and MTR, but T2 is more sensitive to subtle alterations.