Physiological adaptations to resistance exercise as a function of age.

Area of Science:

• Exercise Physiology
• Aging Research
• Metabolic Health

Background:

• The effects of resistance exercise training (RE-T) throughout the lifespan are not well understood.
• Aging is associated with negative physiological changes impacting body composition, function, and metabolic health.

Purpose of the Study:

• To investigate the impact of a 20-week resistance exercise training program on body composition, muscle and vascular function, and metabolic health across different age groups.
• To determine age-specific responses to resistance exercise training, particularly regarding muscle protein synthesis and hypertrophy.

Main Methods:

• A cross-sectional study involving three age cohorts: young (18-28 years), middle-aged (45-55 years), and older (65-75 years).
• All participants completed 20 weeks of supervised, whole-body, progressive resistance exercise training.
• Assessments included body composition, muscle and vascular function, metabolic biomarkers, and muscle protein synthesis (MPS) via stable isotope tracers.

Main Results:

• Resistance exercise training reduced adiposity in young and middle-aged groups, but not older adults.
• Improvements in blood pressure and insulin sensitivity varied by age group, with older adults showing reduced insulin sensitivity post-training.
• Muscle mass increased only in younger individuals, though muscle mechanical quality improved across all ages.
• Acute muscle protein synthesis responses to feeding and exercise were enhanced primarily in younger participants.

Conclusions:

• Resistance exercise training can counteract some age-related declines, but its effectiveness varies significantly with age.
• Certain negative aspects of aging, including reduced muscle mass potential and metabolic adaptations, are not fully reversed by resistance exercise training, even in midlife.