Whole body vibration does not potentiate the stretch reflex

Whole body vibration (WBV) is theorized to enhance neural potentiation of the stretch reflex. The purpose of this study was to determine if WBV affects the quadriceps reflex from a patellar tendon tap. Subjects were 22 volunteers (age 23 +/- 2 yrs, ht 172.8 +/- 10.8 cm, body mass 68.6 +/- 12.3 kg). The stretch reflex was elicited from the dominant leg pre, post, and 30-min post WBV treatment. A matched control group repeated the procedure without WBV. WBV treatment consisted of 5, 1-min bouts at 26 Hz with a 1-min rest period between bouts while maintaining a standardized squatting position. Two-way ANOVAs were used to detect differences between groups over time for vastus medialis (VM) and vastus lateralis (VL) latency, EMG amplitude, electromechanical delay (EMD), and force output. No group x time interactions were detected for latency (VM; F ((2,40)) = 1.20, p = .313: VL; F ((2,40)) = 0.617, p = .544), EMG mean amplitude (VM; F ((2,40)) = 0.169, p = .845: VL; F ((2,40)) = 0.944, p = .398), EMD (VM; F ((2,40)) = 0.715, p = .495: VL; F ((2,40)) = 1.24, p = .301), or quadriceps force (F ((2,40)) = 1.11, p = .341) A single session WBV treatment does not affect the quadriceps stretch reflex in terms of timing or amplitude.