Exercise Intensity and 5-Year Trajectories in Peak Oxygen Uptake in Older Adults: Analysis from the Generation 100 Study

Purpose: The long-term impact of exercise training on change in cardiorespiratory fitness (CRF) with age remains uncertain. Given that CRF appears to be one of the strongest predictors of current and future health, we examined the differences between high intensity training (HIT) and moderate intensity training (MIT) on 5-year changes in CRF in older adults. Methods: In this post-hoc observational analysis of the Generation 100 Study, we included 500 participants (52% women; aged 70-77 years) who consistently reported engaging in HIT or MIT for 5 years. Participants underwent clinical assessments, including CRF measured as peak oxygen uptake (V̇O 2peak ) at four timepoints. Linear mixed model was used to examine the longitudinal change in V̇O 2peak and differences in trajectories across the 5-year period. Results: Across 5 years, men reporting HIT and MIT showed V̇O 2peak declines of -3.1% (p=0.007) and -7.7% (p<0.001), respectively. Women reporting HIT showed no change (p=0.96) in V̇O 2peak , whereas those reporting MIT showed a decline of -4.6% (p<0.001) . At 5-years, the difference in V̇O 2peak was 1.31 mL/kg/min (95% Confidence interval (CI) 0.17 to 2.45) and 1.33 mL/kg/min (95% CI 0.28 to 2.37) in favor HIT, in men and women respectively. In exploratory analyses, higher self-reported exercise intensity was associated with 1.11 (95% CI 0.60 to 1.62) and 0.64 (95% CI 0.22 to 1.06) mL/kg/min smaller decline in V̇O 2peak in men and women, respectively, whereas weekly exercise duration showed weaker and inconsistent associations. Conclusions: Among men and women aged 70-77 years, consistent engagement in aerobic exercise training was associated with more favorable age-related V̇O 2peak trajectories , with HIT showing the smallest declines over 5 years. Exploratory interaction analyses suggested that exercise intensity may become increasingly important over time for preserving V̇O 2peak .