This study tested the hypothesis that rate of force development (RFD) would be a more sensitive indirect marker of muscle damage than maximum voluntary isometric contraction (MVC) peak torque. Ten men performed one concentric cycling and two eccentric cycling (ECC1, ECC2) bouts for 30 min at 60% of maximal concentric power output with 2 weeks between bouts. MVC peak torque, RFD, and vastus lateralis electromyogram amplitude and mean frequency were measured during a knee extensor MVC before, immediately after and 1-2 days after each bout. The magnitude of decrease in MVC peak torque after exercise was greater (P < 0.05) for ECC1 (11-25%) than concentric cycling (2-12%) and ECC2 (0-16%). Peak RFD and RFD from 0-30 ms, 0-50 ms, 0-100 ms, to 0-200 ms decreased (P < 0.05) immediately after all cycling bouts without significant differences between bouts, but RFD at 100-200 ms interval (RFD(100-200)) decreased (P < 0.05) at all time points after ECC1 (24-32%) and immediately after ECC2 (23%), but did not change after CONC. The magnitude of decrease in RFD(100-200) was 7-19% greater than that of MVC peak torque after ECC1 (P < 0.05). It is concluded that RFD(100-200) is a more specific and sensitive indirect marker of eccentric exercise-induced muscle damage than MVC peak torque.

Eccentric cycling was less metabolically demanding than concentric cycling, and HR and BLa were further reduced during ECC2. Muscle damage is minimal after ECC2 and should not influence the choice to undertake eccentric cycling training.

To compare the shoulder functions of the pitching and non-pitching sides of patients with throwing shoulder injuries. [Subjects and Methods] The subjects were 44 male baseball players. Scapulohumeral and scapulothoracic shoulder-joint functions (7 ROM items, 13 strength measures) of the pitching and non-pitching sides were compared. [Results] On the pitching side, the retroversion angle of the humeral head and the secondary external rotation angle were significantly large, whereas the values of the secondary internal rotation angle, horizontal flexion test, scapular retraction test, inner muscle strength, and the strength of the muscle fibers of the lower trapezius muscle were either significantly lower, or smaller. [Conclusion] The results suggest that characteristic differences in shoulder functions related to ROM and muscle strength of the pitching and non-pitching sides seen in cases of throwing shoulder injury are strongly related to shoulder pain at the time of throwing.

No abstract

To examine and compare the effectiveness of three self-stretch methods for secondary internal rotation limitation in injured throwing shoulders. [Subjects] Forty-eight baseball players with injured throwing shoulders. [Methods] First, inability to perform the APS, CB, and IRS stretch methods due to pain were compared among the subjects. Then, the 28 cases who could perform all of the stretch methods were divided into 3 groups, and excluding the effect of the retroversion angle, the secondary internal rotation angle was measured before and after stretch performance and compared among the groups. [Results] The inability to perform stretching due to pain was significantly the lowest for the APS method. There were no significant differences in the secondary internal rotation angle among the groups before stretching, but after stretching, those of the groups performing the APS and CB methods were significantly larger than that of the IRS method group. [Conclusion] The results suggest that the APS method is the most effective self-stretch method for injured throwing shoulders.