HIIT preserved lean mass—but the advantage was small
Editorial draft · Reviewed October 15, 2026. Original source scope and limitations retained.
Randomised trial sub-study · 123 healthy older adults
A six-month exercise trial offers a restrained answer to a common question: does harder training improve body composition more in later life? High-intensity interval training preserved lean mass, but the investigators judged the differences small and not clinically meaningful after considering measurement error.
The Maturitas study randomised 123 healthy older adults, average age 72, to high-intensity intervals, moderate-intensity training or a low-intensity active control. Participants completed three supervised 45-minute sessions weekly. Body composition was measured using DXA scans.
Both higher-intensity groups reduced fat more than the control group. Moderate-intensity training was associated with a reduction in fat-free mass, whereas HIIT maintained lean mass. Both approaches produced comparable improvements in visceral fat.
Lean mass includes more than skeletal muscle. These results therefore do not establish that HIIT prevented sarcopenia, improved strength or preserved everyday function. Nor did the trial compare HIIT with a dedicated resistance-training programme.
The practical message is that intensity may matter, but the size and relevance of the effect matter too. Training should match health status, capacity and supervision. The study appeared in December 2025; recent coverage does not make it a new 2026 trial.