The impact of resistance exercise training (RE-T) across the life span is poorly defined.
To resolve this, we recruited three distinct age cohorts of young (18–28 years; n = 11), middle-aged (45–55 years; n = 20), and older (nonsarcopenic; 65–75 years; n = 17) individuals to a cross-sectional intervention study. All subjects participated in 20 weeks of fully supervised whole-body progressive RE-T, undergoing assessment of body composition, muscle and vascular function, and metabolic health biomarkers before and after RE-T. Individuals also received stable isotope tracer infusions to ascertain muscle protein synthesis (MPS).
There was an age-related increase in adiposity, but only young and middle-age groups demonstrated reductions following RE-T. Increases in blood pressure with age were attenuated by RE-T in middle-aged, but not older, individuals, while age-related increases in leg vascular conductance were unaffected by RE-T. The index of insulin sensitivity was reduced by RE-T in older age. Despite being matched at baseline, only younger individuals increased muscle mass in response to RE-T, and there existed a negative correlation between age and muscle growth; in contrast, increases in mechanical quality were preserved across ages. Acute increases in MPS (upon feeding plus acute RE-T) were enhanced only in younger individuals, perhaps explaining greater hypertrophy.
Our data indicate that RE-T offsets some, but not all, negative characteristics of ageing — some of which are apparent in midlife.
Phillips, B. E., Williams, J. P., Greenhaff, P. L., Smith, K., & Atherton, P. J. (2017). Physiological adaptations to resistance exercise as a function of age. JCI insight, 2(17), https://doi.org/10.1172/jci.insight.95581