Effects of isometric vs. dynamic resistance training on muscle performance and body composition: Protocol for a pilot study

Abstract

Background

Isometric resistance training (ISO-RT) has gained renewed attention for its potential to elicit muscular adaptations and enhance athletic performance. Unlike dynamic resistance training (DYN-RT), ISO-RT involves no joint movement or eccentric loading, making it particularly suitable for individuals with joint pathologies or those undergoing rehabilitation. Despite increasing interest, the comparative effectiveness of ISO-RT versus DYN-RT across various outcomes, including strength, hypertrophy, endurance, and recovery, remains inadequately explored.

Aims

This study aims to evaluate and compare the effects of multi-angle ISO-RT and traditional DYN-RT on muscle performance, body composition, and recovery-related indicators in healthy adults.

Methods

In this pilot randomised controlled trial, 20 healthy adults (≥18 years) will be randomly assigned to either the ISO-RT or DYN-RT group (n ​= ​10 per group). Both groups will complete a full-body resistance training program twice weekly for six weeks. The key distinction lies in the execution of the chest press and leg press exercises—performed isometrically in the ISO-RT group and dynamically in the DYN-RT group. All outcomes will be assessed at baseline and post-intervention.

Analysis

Primary outcomes include dynamic and isometric strength. Secondary outcomes encompass muscular power, dynamic and isometric endurance, body composition (via dual-energy X-ray absorptiometry), muscle oxygenation (via near-infrared spectroscopy), and subjective recovery indicators such as sleep quality and delayed onset muscle soreness. Between-group comparisons will be conducted using appropriate inferential statistical tests to determine effect estimates and feasibility metrics.

Discussion/implications

This trial will offer preliminary insights into the physiological and perceptual adaptations elicited by ISO-RT versus DYN-RT. The findings will inform the design of larger-scale trials and contribute to developing tailored, evidence-based resistance training guidelines for both clinical and athletic populations.