HIIT preserved lean mass in older adults, but clinical significance remains uncertain

A trial published in Maturitas compared three exercise intensities in 123 healthy older adults from Greater Brisbane, Australia. Participants had a mean age of 72 years and an average BMI of approximately 26 kg/m². They completed three supervised, 45-minute gym sessions weekly for six months, assigned to high-intensity interval training (HIIT), moderate-intensity exercise or a low-intensity comparison group. Scan-based body composition assessments were conducted at baseline, three months and six months.

All groups experienced modest fat loss. High- and moderate-intensity training significantly reduced fat mass, with greater improvements than low-intensity exercise. HIIT preserved lean mass, whereas moderate-intensity exercise was associated with a small decline. Both higher-intensity groups also showed improvements in visceral adipose tissue. The supplied report does not provide numerical effect sizes or confidence intervals.

The findings suggest a potential role for supervised HIIT in maintaining lean tissue during fat loss in healthy older adults. However, the researchers emphasized that improvements were small and differences compared with low-intensity exercise were not clearly clinically meaningful after considering measurement uncertainty. Scans measured lean tissue, which includes water and nonmuscle tissues, rather than muscle strength or functional independence. This secondary account does not establish benefits for frail older adults or unsupervised exercise.