Effect of age on muscle hypertrophy induced by resistance training.
Level 3 - non-randomized controlled study
Non-randomized prospective cohort study comparing two age groups undergoing a standardized intervention.
PubMed 8914498 · doi:10.1093/gerona/51a.6.m270
What was done
Nine young adults (22–31 years, 5 male and 4 female) and eight older adults (62–72 years, 4 male and 4 female) underwent 3 months of progressive resistance training with training loads proportional to baseline strength. Muscle cross-sectional area (CSA) in the thigh and upper arm was measured before and after training using magnetic resonance imaging (MRI). Muscle strength was measured by 3-repetition-maximum (3RM) testing to evaluate changes in CSA and specific tension (ratio of 3RM strength to CSA).
What was found
Pretraining 3RM strength per cm² CSA was lower in the older group for elbow flexors (16 ± 6% lower, p < .02), knee flexors (40 ± 7% lower, p < .001), and knee extensors (19 ± 9% lower, p < .05). Training-induced increases in muscle CSA were significantly smaller in older adults for elbow flexors (9 ± 4% in old vs 22 ± 4% in young, p < .05) and knee flexors (1 ± 2% in old vs 8 ± 2% in young, p < .01), but not knee extensors (6 ± 2% in old vs 4 ± 1% in young). Increases in specific tension were similar between groups for elbow flexors (19 ± 5% in old vs 21 ± 5% in young) and knee extensors (32 ± 14% in old vs 38 ± 6% in young), but greater in older adults for knee flexors (64 ± 13% in old vs 28 ± 5% in young, p < .02).
Why it matters
This study shows that aging can attenuate muscle hypertrophic gains in specific muscle groups during resistance training, yet older muscle retains the capacity for significant strength and specific tension improvements.
Limits
The study is constrained by a very small sample size (n=17 total), a short 3-month intervention period, and a non-randomized cohort design comparing age groups. Nutritional intake, long-term functional outcomes, and cellular mechanisms were not reported in the abstract.
Cited by
- contradicts Elderly individuals, such as 70-year-olds who have never lifted weights, gain a similar amount of muscle as a percentage of starting lean mass when they begin resistance training.