Context: Paresis associated with motor-incomplete spinal cord injury (SCI) impairs function. Whole body vibration (WBV) may increase strength by activating neuromuscular circuits.
Objective: We assessed effects of a single session of WBV on lower extremity strength in individuals with motor-incomplete SCI.
Design: A single-session blinded randomized controlled trial.
Setting: Rehabilitation research laboratory.
Participants: Subjects (n = 25; age 49.7 ± 12.5 years) had chronic SCI (>1 year) and were able to stand for at least 45 seconds. Interventions Subjects were randomized either to WBV (n = 13) consisting of four 45-second bouts with 1-minute intervening rest periods (frequency: 50 Hz, amplitude: 2 mm) or to sham electrical stimulation (n = 12).
Outcome measures: Maximal voluntary isometric quadriceps force was measured with a fixed dynamometer. A modified Five-Time-Sit-To-Stand (FTSTS) test was used to assess functional lower extremity strength. Measures were made at pre-test, immediate post-test, and delayed post-test 20 minutes later.
Results: At immediate post-test, change in voluntary isometric force in the WBV group was 1.12 kg greater than in the sham group. The within-group change for the WBV group was significant with a moderate effect size (P = 0.05; ES = 0.60). No force-related changes were observed in the sham group. The modified FTSTS scores improved in both groups, suggesting that this measure was subject to practice effects.
Conclusion: Evidence from the present study suggests that even a single session of WBV is associated with a meaningful short-term increase in quadriceps force-generating capacity in persons with motor-incomplete SCI. The multi-session use of WBV as part of a strengthening program deserves exploration.
Keywords: Lower extremity; Rehabilitation; Spinal cord injuries; Strength; Vibration.