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This study investigates the relation between T2-weighted MR image and delayed onset muscle soreness. Five healthy men (Mean ± SD. age: 23.4 ± 3.2 yr: height: 172.6 ± 5.5 cm; weight: 62.8 ± 6 kg) participated in this study. All subjects performed the ankle plantar flexion exercise including eccentric contraction (12 repetitions, 5 sets). Transaxial T2-weighted images of triceps surae muscle were obtained using a 1.5 Tesla superconducting imaging system before and 24, 48, 96, and 168 hours after exercise. T2 relaxation time (T2 value) was calculated for the medial gastrocnemius on the dominant side before and after exercise. In addition, the muscle soreness level was assessed at the same time as MRI measurements. All subjects showed the muscle soreness at 24-96 hours after exercise, while only 3 subjects showed the increased tendency in T2 value after post-exercise 48 hours. Elevation of T2 value is associated with increased intramuscular water content, and thus the present study suggests that exercise-induced edema is not always a determinant factor in delayed onset muscle soreness. [ABSTRACT FROM AUTHOR]

The purpose of this study was to investigate quantitatively and non-invasively the muscle recruitment of the rotator cuff muscles in baseball pitching using MR imaging. Five healthy baseball pitchers (Mean ± SD, age; 23.2 ± 1.3 yr; height: 171.8 ± 6.72cm; weight: 68.8 ± 5.4kg) participated in this study. Subjects threw 135 pitches from the hand-made pitcher's mound in 9 innings. T2-weighted images of rotator cuff muscles were obtained using a 1.5 Tesla superconducting imaging system with an E1 shoulder coil before and Immediately after baseball pitching. T2 relaxation times (T2) before and after pitching were calculated for the supraspinatus muscle, the shoulder external rotator muscle group (the infraspinatus muscle and teres minor muscle) and the subscapularis muscle. This study revealed that T2 values in all rotator cuff muscles tended to increase immediately after baseball pitching. T2 elevation would be associated with an exercise-induced increase in intramuscular water content and he limited to those muscles which were active during the exercise. In addition, greater mean force production during exercise translated into greater increases in T2 values for the active muscles. Judging from the relative T2 elevation immediately after pitching, the present study showed that there was personal equation among the muscles exhibiting the greatest T2 value after baseball pitching. [ABSTRACT FROM AUTHOR]