HIIT reduces sarcopenia risk and preserves grip strength in older adults over 5-year RCT

BACKGROUND: Early prevention of sarcopenia through exercise is vital to health, independence and mortality risk in older adults; however, there is a scarcity of evidence concerning the long-term effects of aerobic exercise alone. We tested the primary hypothesis that a 5-year decline in key defining components of sarcopenia is less in an aerobic exercise group compared with a control group. Secondly, we tested the same hypothesis using a model of 'clinically defined sarcopenia'. METHODS: Norwegian community dwelling older adults (n = 1567; aged 70-75 years at inclusion) participated in the Generation 100 Study. They were randomized in a 1:1:2 ratio-stratified by sex and cohabitation status to either moderate intensity continuous training (MICT, n = 387) or high intensity interval training (HIIT, n = 400), or to a control group following the Norwegian physical activity guidelines (CON, n = 780). Key defining components of sarcopenia were grip strength (kilograms), skeletal muscle index (kg/m) and gait speed (m/s). Clinically defined sarcopenia was based on the European Working Group on Sarcopenia in Older People and recent normative data for the Norwegian population. An intention to treat linear mixed model and an ordinal logistic regression mixed model were used to examine the effects of aerobic exercise on sarcopenia on the 1, 3 and 5 years follow-up. p values for the main hypothesis were adjusted using the Benjamini-Hochberg correction. RESULTS: Mean age across groups was 72 years of age, including ~50% women, ~50% with higher education, 86%-90% with good or very good health and 73%-76% considered physically active. Compared with CON, grip strength declined less for HIIT at Year 1 (estimated difference of 0.98 kg; p < 0.001) and Year 3 (estimated difference of 0.03 kg; p = 0.016). At Year 3, HIIT increased their gait speed by 0.01 m/s (estimated difference between HIIT vs. CON of 0.03 m/s; p = 0.016). At Year 5, all groups declined from baseline (CON -0.07; MICT -0.10 and HIIT -0.04 m/s). Participants determined as having 'clinically defined sarcopenia' at baseline, Years 3 and 5 were: 22%, 58% and 63% (CON); 20%, 55% and 67% (MICT) and 19%, 50% and 56% (HIIT). Odds for developing clinically defined sarcopenia were significantly lower for HIIT (OR = 0.51; p = 0.018 at Year 3; OR = 0.47; p = 0.009 at Year 5) as compared with CON. No effects were found for MICT. CONCLUSIONS: The study demonstrates that in addition to having a protective cardiovascular effect, HIIT also has a beneficial effect on muscle strength and physical performance in a relatively healthy population of older adults.