The Long-term Effect of Different Exercise Intensities on High-Density Lipoprotein Cholesterol in Older Men and Women Using the Per Protocol Approach: The Generation 100 Study.

Objective: To examine whether 5 years of high-intensity interval training (HIIT) increases high-density lipoprotein cholesterol (HDL-C) concentration more than moderate-intensity continuous training (MICT) and control (CON) in older men and women.

Methods: A total of 1567 older adults (790 [50.4%] women) were randomized (2:1:1) to either CON (n=780; asked to follow the national recommendations for physical activity) or 2 weekly sessions of HIIT (10-minute warm-up followed by 4×4-minute intervals at ∼90% of peak heart rate) or MICT (50 minutes of continuous work at ∼70% of peak heart rate). Serum HDL-C concentration was measured by standard procedures at baseline and at 1 year, 3 years, and 5 years. The study took place between August 21, 2012, and June 31, 2018. Linear mixed models were used to determine between-group differences during 5 years using the per protocol approach.

Results: Men in HIIT had a smaller reduction in HDL-C (-1.2%) than men in CON (-6.9%) and MICT (-7.8%) after 5 years (=.01 and =.03 for CON vs HIIT and MICT vs HIIT, respectively). No effect of exercise intensity on HDL-C was seen in women. Changes in peak oxygen uptake were associated with changes in HDL-C in both men and women, whereas changes in body weight and fat mass were not.

Conclusion: In men, HIIT seems to be the best strategy to prevent a decline in HDL-C during a 5-year period. No effect of exercise intensity was seen for older women.

Trial Registration: ClinicalTrials.gov identifier: NCT01666340.