# A graded personalized exercise program’s effect on muscle and body fat: randomized controlled trial

## TL;DR

A personalized exercise program improved muscle thickness and reduced body fat in middle-aged adults, showing benefits for physical fitness and long-term health.

## Contribution

This study introduces a graded personalized exercise program tailored by age, sex, and activity level for middle-aged adults.

## Key findings

- The program significantly increased abdominal muscle thickness and reduced body fat percentage and waist circumference.
- It also positively affected various physical fitness indicators in participants.
- The study supports early preventive exercise to mitigate sarcopenia risk in later life.

## Abstract

With population aging, personalized exercise programs considering clinical and demographic factors like sex, age, and physical activity level are essential; however, research on their effects remains limited. We aimed to evaluate the effectiveness of a Global Physical Activity Questionnaire-based graded personalized exercise program tailored for middle-aged adults aged 40–69 years.

We enrolled 71 middle-aged adults in their 40s, 50s, and 60s (approximately 20 participants per age group) in a parallel-group randomized controlled trial.

Participants were assigned using age-stratified randomization to a treatment or control group. Participants were categorized into three levels according to weekly physical activity measured by the Global Physical Activity Questionnaire and physical activity guidelines for adults. Each participant’s grade was determined by applying equal weight adjustments for sex, age, and physical activity level, and the participants were assigned an exercise program corresponding to their grade. The exercise intervention consisted of a circuit training program alternating between aerobic and anaerobic exercises. The control group was instructed to maintain their usual physical activity levels.

Changes from before to after exercise in clinical results (body composition, physical fitness, ultrasound-measured muscle/fat thickness, and biochemical data) were recorded during the 8-week exercise program and differences between pre- and post-exercise values of the groups were analyzed using the t-test and Wilcoxon rank-sum test.

Among 64 participants who had completed the program, 33 (51.5%) participated in the exercise program. The exercise program significantly increased abdominal muscle thickness (p < 0.01), reduced body fat percentage (p = 0.02) and waist circumference (p = 0.01), and positively affected various physical fitness indicators.

This study demonstrated the beneficial effects of a graded personalized exercise program on muscle thickness, body fat, and physical fitness and offers key data to support early preventive exercise programs in middle-aged adults to mitigate the risk of sarcopenia in later life.

Registered on November, 29, 2024 at cris.nih.go.kr identifier KCT0009970.

The online version contains supplementary material available at 10.1186/s12889-025-22453-5.