The Effects Of High Load And Low Load Unilateral Bicep Training On Changes In Post-activation Performance Enhancement

Abstract

Post-activation performance enhancement (PAPE) represents the short-term improvement in muscle performance following a conditioning stimulus. Previous research has shown that PAPE is enhanced following high-load training. Since PAPE represents a local response, we hypothesize that this effect might provide insight into changes at the muscle level, which might influence strength adaptations. To test this, we compared PAPE following two training protocols known to produce differences in maximal strength. PURPOSE: To determine if PAPE is augmented to a greater extent following high load training compared to low load training. METHODS: 13 participants (3 males) were randomly assigned to a group completing high-load exercise with their dominant arm, and low-load exercise with their non-dominant arm. This is part of a larger ongoing study, which is why conditions were not counter-balanced based on dominancy. The high load training consisted of performing a 1RM test (five attempts maximum), followed by 4 sets of traditional exercise (~8-12 repetitions). The low-load condition completed 4 sets of exercise, aiming for ~30-40 repetitions. 18 sessions of elbow flexion exercise were completed over six weeks. PAPE was measured before and after training using isokinetic dynamometry at 210 deg/sec. PAPE testing began with a warm-up, the pre-conditioning torque attempt, the 6 s isometric conditioning stimulus, followed by the post-conditioning torque attempt 3 minutes later. There were two hypotheses: H0: differences would be equal or H1: greater following training (specifically high load training in comparison across conditions). Hypotheses were tested using Bayes Factors for Informative Hypotheses (BAIN). RESULTS: PAPE was not greater following six weeks of high-load (Pre Δ: 1.6 Nm vs. Post Δ: 0.26 Nm, BF01: 11.2) or low-load (Pre Δ: 0.33 Nm vs. Post Δ: -0.32 Nm, BF01: 5.6) resistance training. The available data suggests that each condition changed similarly across time (difference of -0.7 Nm, BF01: 5.4). CONCLUSIONS: Preliminary data suggests that high load, as well as low load, training for six weeks does not result in an improvement in PAPE, when performing unilateral bicep exercise. As such, high load training does not appear to be superior to low load training for improved PAPE responses.