Effects of simultaneous neuromuscular electrical stimulation and static stretching on flexibility and strength: a randomized controlled trial.

[Purpose] This study aimed to determine the effects of simultaneous neuromuscular electrical stimulation (NMES) and static stretching on flexibility and muscle strength. [Participants and Methods] A randomized controlled trial was conducted with 96 healthy university students equally assigned to either a simultaneous NMES and static stretching group (Group S) or an NMES-only group (Group C). The gastrocnemius muscle was the target of both NMES and static stretching. Ankle dorsiflexion angle (DFA), forward flexion distance (FFD), and ankle plantar flexor strength (PFS) were measured before and directly following intervention. Outcomes in the two groups were evaluated using two-way analysis of variance. [Results] A significant time effect was observed for both DFA and FFD, whereas a significant interaction effect was observed for FFD only. Improvements in DFA were similar between the groups; however, improvements in FFD were significantly greater in Group S. PFS showed no significant interaction between the group and the time factor. [Conclusion] Our findings suggest that simultaneous intervention enhances flexibility. Despite targeting the gastrocnemius muscle, the observed improvement in hamstring flexibility may have been because of fascial connections. These findings support the efficacy and safety of NMES combined with static stretching for increasing flexibility.