Kinetic analysis of concurrent activation potentiation during back squats and jump squats.

Concurrent activation potentiation enhances muscular force during open kinetic chain isometric and isokinetic exercises via remote voluntary contractions (RVCs). The purpose of this study was to evaluate the effect of RVCs on the performance of closed kinetic chain ground-based exercises. Subjects included 13 men (21.4+/-1.5 years) who performed the back squat and jump squat in 2 test conditions. The RVC condition included performing the test exercises while clenching the jaw on a mouth guard, forcefully gripping and pulling the barbell down into the trapezius, and performing a Valsalva maneuver. The normal condition (NO-RVC) included performing the test exercises without RVCs. Exercises were assessed with a force platform. Peak ground reaction force (GRF), rate of force development (RFD) during the first 100 milliseconds (RFD-100), RFD to peak GRF (RFD-P), and jump squat height (JH) were calculated from the force-time records. Data were analyzed using an analysis of variance. Results reveal that GRF and RFD-100 were higher in the RVC compared with the NO-RVC condition for both the back squat and jump squat (p<or=0.05). The RFD-P was higher in the RVC compared with NO-RVC condition for the jump squat (p<or=0.05) but not for the back squat (p=0.82). The JH was higher in the RVC compared to the NO-RVC condition for the jump squat (p<or=0.05). This study demonstrates that RVCs enhance the performance of closed kinetic chain exercises for most of the outcome variables assessed, yielding a 2.9-32.3% greater performance. Practitioners should encourage athletes to use RVCs to improve the acute training effect of exercises such as those used in this study.