Peer-reviewed studies, explained clearly

Physical activity was associated with slightly better late-life global cognition (standardized coefficient 0.03) and lower incidence of cognitive decline in some analyses, but associations were weak with no clear dose–response pattern.

Weightlifting 1–2 times/week was associated with 9% lower all-cause mortality after adjusting for aerobic activity; combined aerobic plus weightlifting showed lower mortality than aerobic activity alone in joint models.

Aging was associated with lower mitochondrial capacity, exercise capacity and efficiency, gait stability, muscle function, and insulin sensitivity even when daily activity was similar. Exercise-trained older adults largely did not show those gaps. Mitochondrial capacity correlated with exercise efficiency and insulin sensitivity.

Higher daily step counts were associated with lower all-cause mortality in adjusted models; higher step intensity showed additional benefit in this cohort. Thresholds and hazard ratios are reported in the primary publication.

WHO recommends regular aerobic activity for adults and, for older adults, also emphasizes muscle-strengthening and balance training at least 3 days/week when safe—along with reducing sedentary time.

Adults should do at least 150–300 minutes/week of moderate-intensity aerobic activity (or equivalent vigorous activity) plus muscle-strengthening activities involving all major muscle groups on 2 or more days per week.

Active older adults had mitochondrial capacity and exercise efficiency similar to active younger adults. Sedentary older adults were lower on those measures and slower on chair stands and stair climbing. Mitochondrial capacity was related to muscle performance and physical function.

All three modes improved insulin sensitivity and lean mass. High-intensity aerobic intervals and combined training improved aerobic capacity and muscle mitochondrial respiration, with a strong response in older adults. Interval training shifted many age-related muscle protein patterns.

Light and moderate joggers had lower mortality than sedentary non-joggers in adjusted analyses; strenuous joggers did not differ significantly from sedentary non-joggers in this observational sample (see paper for full subgroup results).

Meeting recommended activity levels (150 min/week moderate or equivalent) was associated with lower mortality; benefits were largest when comparing inactive adults with those meeting guidelines, with possible plateau at higher volumes.

Endurance training and combined training increased muscle mitochondrial oxidative capacity. Strength, fitness, and body composition improved with training. Most adaptations did not depend on age.

Lower mitochondrial capacity and efficiency were associated with lower aerobic capacity and slower preferred walking speed.

Each 1-MET higher fitness was associated with 13% lower all-cause mortality (RR 0.87, 95% CI 0.84–0.90) and 15% lower CHD/CVD events (RR 0.85, 95% CI 0.82–0.88). Low vs high fitness categories showed substantially higher event rates.