# Acute effects of predominantly inertial load-induced post-activation potentiation on upper-body muscle mechanics: implications for racket sports performance

## TL;DR

This study shows that inertial loading can boost upper-body explosive performance, which could benefit racket sports athletes.

## Contribution

The novel use of inertial loading to induce PAP and its impact on upper-body mechanics in racket sports contexts.

## Key findings

- Movement velocity and maximal power increased significantly after PAP.
- Maximal force decreased, shifting the force–velocity relationship to the right.
- Predominantly inertial loading effectively enhances explosive upper-body performance.

## Abstract

This study investigated the acute effects of post-activation potentiation (PAP) induced by predominantly inertial loading on upper-body muscle mechanics, with particular consideration for applications in racket sports performance.

Fifteen participants experienced in resistance training completed two testing sessions. During the first session, participants underwent anthropometric assessment, familiarization with the bench press throw under inertial resistance, and determination of one-repetition maximum (1RM). The second session included a pre-test, a PAP protocol consisting of 2 sets of 3 ballistic chest press repetitions at approximately 80%–90% 1RM with inertial loading (rubber bands counteracted gravitational force to provide predominantly inertial load), followed by a post-test after five minutes of standardized rest. Performance variables—movement velocity, power, and maximal force—were recorded.

Results demonstrated significant increases in movement velocity and maximal power output following PAP (p ≤ 0.05), while maximal force significantly decreased. Consequently, the force–velocity relationship exhibited a rightward shift.

These findings indicate that predominantly inertial loading can effectively elicit PAP and enhance explosive upper-body performance. Such effects may be particularly beneficial for athletes in racket sports, where rapid, high-velocity upper-limb actions performed under light external loads are critical for optimizing stroke power and precision.