(44) MULTIPLE CASE DESIGN COMPARISON OF TWO FRENCH CONTRAST METHODS ON POST ACTIVATION PERFORMANCE ENHANCEMENT WITH EMG AND FORCE.

Background: Finding optimal sequences of muscle movements to activate neural and performance parameters remains a central focus for coaches. French contrast methods (FCM) employ heavy resistance/force, plyometric, weighted plyometric, and assistive exercises sequencing that contrast types of contractions to optimize performance. Limited data exists to compare these techniques with neural and performance parameters. PURPOSE: To compare two routines of FCM on EMG and strength changes the goal was to determine if post-activation performance enhancement was realized. METHODS: Five participants (26.6 yrs, 171 cm, 65.4 kg) were randomly assigned to one of two FCM cycles. The two randomly assigned and counterbalanced conditions were organized such that pre and post-tests were performed with a 5-second mid-thigh pull (Crane Strain gauge) while EMG (Bionomadix wireless Biopac) recorded activation of the vastus lateralis and the medial head of the Gastrocnemius. Program 1 consisted of a heavy leg press, 90% 1-RM 2 repetitions, 6 cone hops, 6 trap bar jumps with 30% of body weight, and then 3 resistance sprints for 15 yards. Program 2 consisted of a 30-second maximal isometric mid-thigh pull, 5 kettlebell swings, 6 resistance broad jumps, and 6 recovery broad jumps. These programs were performed for 3 rounds. Also, rounds were done with 30 seconds to 2 minutes between rounds. After each program, 3-5 minutes of recovery was given. RESULTS: For program 1, a slight enhancement of force was observed but a decrease of force was observed for program 2 (see Figure 1). Neither was statistically significant. However, the EMG data demonstrated that the Vastus Lateralis was significantly more activated than the pre-test measures during program 2 (t=3.14, p< 0.05). Age was determined to be a significant factor in the analysis of variance as older participants in this multiple case design trained in mixed modes while younger participants mainly engaged in running. CONCLUSIONS: The FCM routines impacted EMG more when isometric forces were applied in this sample. Specifically, the sequence of program 2 activated the vastus lateralis differently than program 1. Statistically, this study was unable to provide conclusive evidence of post-activation performance enhancement for FCM. PRACTICAL APPLICATIONS:  FCM routines did not provide a clear pattern of potentiation. Evidence for isometric-based forces before dynamic exercise was observed. Coaches should consider training status and age as factors that may impact the application of FCM.

Acknowledgements: None