Background: To evaluate the effects of a motion-triggered neuromuscular electrical stimulation (NMES) shoulder strengthening program on rotational shoulder strength and throwing velocity in healthy, elite-level handball players. Methods: Fourteen male handball players were randomly allocated (1:1) to either the NMES or control group. Participants were assessed by a blinded investigator at baseline and after 6 weeks for clinical status, isometric dynamometer-based external (ER) and internal rotational (IR) maximal shoulder strength, and handball endurance and maximal throwing velocity (7 m free throw). Between time points, NMES subjects completed a standardized motion-triggered NMES shoulder strengthening program (3 sessions/week, 30 min for 6 weeks), whereas controls performed a conventional standardized strength program. Results: After completion of the motion-triggered NMES program, all NMES participants (100%) demonstrated significant gains in isometric ER strength (+1.4 ± 1.1 kg, p = 0.016) compared with 43% of controls, who demonstrated no overall improvement (−0.2 ± 1.8 kg, p = 0.740). Similarly, a significantly greater proportion of NMES participants improved endurance throwing velocity compared with controls (100% vs. 29%, p = 0.004), with a mean increase of +2.9 ± 2.8 km·h−1 (p = 0.0.56). Maximum throwing velocity showed no between-group differences in the proportion of athletes with improved results (p = 0.899). Conclusions: A six-week motion-triggered NMES shoulder strengthening program improved external rotation strength and increased the proportion of athletes demonstrating enhanced endurance throwing velocity under fatigued conditions. However, when compared with conventional exercise alone, NMES did not confer additional benefits for maximal throwing velocity in this study. Therefore, NMES should be regarded as a complementary modality rather than a substitute for established shoulder strengthening exercises.
Conner-Rilk et al. (Wed,) studied this question.