Differences in post-exercise T2 relaxation time changes between eccentric and concentric contractions of the elbow flexors
This study compared maximal eccentric (ECC) and concentric (CON) contractions of the elbow flexors for changes in transverse relaxation time (T2) and indirect markers of muscle damage.
Twelve young men performed five sets of six maximal isokinetic (30°/s) ECC with one arm followed by CON with the other arm. Magnetic resonance images to assess T2 and cross-sectional area (CSA) of biceps brachii, brachialis, and brachioradialis, and measurements of maximal voluntary isometric contraction (MVC) torque, range of motion (ROM), and muscle soreness were taken before, immediately after, and 1, 3, and 5 days after each exercise.
MVC torque and ROM decreased greater after ECC than CON (p < 0.05), and muscle soreness developed only after ECC. Biceps brachii and brachialis CSA increased immediately after CON, but delayed increases in brachialis CSA were found only after ECC (p < 0.05). T2 of the muscles increased greater after CON (27–34 %) than ECC (16–18 %) immediately post-exercise (p < 0.05), but returned to baseline by 1 day after CON. The biceps brachii and brachialis T2 increased by 9–29 % at 1–5 days after ECC (p < 0.05). The post-ECC T2 changes showed no significant correlations with the changes in MVC torque, muscle soreness, and CSA, but the T2 increase immediately post-ECC was correlated with the peak T2 in 1–5-day post-ECC (r = 0.63, p < 0.05).
These results suggest that muscle activity during exercise was lower in ECC than CON, and the T2 changes after ECC do not necessarily relate to the changes in other indirect markers of muscle damage.
KeywordsMuscle damage Transverse relaxation time Cross-sectional area Magnetic resonance imaging Delayed onset muscle soreness Muscle function
Analysis of variance
Delayed onset muscle soreness
Magnetic resonance imaging
Maximal voluntary isometric contraction
Region of interest
Range of motion
Transverse relaxation time
Visual analog scale
This study was supported by the Grant-in-Aid for Young Scientists (B; 20614473).
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
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