# Effectiveness of combined exercise intervention on sedentary behaviour patterns, body composition, and cardiometabolic health among middle-aged adults

## TL;DR

A 7-week exercise program improved body composition and health in middle-aged adults, but did not change how much they sat, with bigger benefits for those who already took more breaks.

## Contribution

A combined MICT and HIIT program was tested for its impact on sedentary behavior and health in middle-aged adults.

## Key findings

- The Breaker group showed increased MVPA and reduced body fat and cholesterol after the intervention.
- The program improved cycling and rowing performance in the Breaker group.
- Sedentary bout duration did not significantly change in any group.

## Abstract

Sedentary behaviour (SB) presents a health risk independent of age, sex, and clinical disease status, while exercise interventions have been shown to potentially reduce sitting time. This study examined the effectiveness of a combined moderate-intensity continuous training (MICT) and high-intensity interval training (HIIT) program on SB patterns, body composition, and exercise performance among middle-aged adults.

Quasi-experimental intervention study without a control group.

Thirty-two adults (50% women, aged 38.25 ± 8.27) completed a 7-week program with three weekly sessions of cycling (MICT) and rowing (HIIT). Baseline accelerometer data were used to classify participants into Breaker (≤ 15 min sedentary bouts), Intermediator (15–20 min), and Prolonger (≥ 20 min) groups. Paired-sample t-tests and repeated measures ANOVAs assessed changes, with effect sizes reported as η²p and Cohen’s d.

After intervention, the Breaker group showed increased breaks per sedentary hour and greater time in moderate-to-vigorous physical activity (MVPA) compared with Intermediator and Prolonger groups (all p < 0.05). Breakers also reduced body fat percentage, waist–hip ratio, and total cholesterol (p < 0.05–0.01), alongside improved maximum cycling (p = 0.001) and rowing load (p = 0.02). The Intermediator group demonstrated a reduction in body fat percentage (p = 0.005). However, mean sedentary bout duration, reflecting sedentary behaviour accumulation patterns, did not change significantly in any group (p > 0.05).

The 7-week combined exercise training improved body composition, cardiometabolic profile, and exercise performance but did not alter sedentary behaviour patterns in middle-aged adults. Nonetheless, individuals with shorter sedentary bouts experienced significant health and performance benefits than those with prolonged bouts, suggesting that baseline sedentary profiles may moderate responsiveness to exercise interventions.

The online version contains supplementary material available at 10.1186/s13102-025-01488-6.