Resistance training increases insulin-like growth factor-1, strength, physical function, and mental flexibility in female older adults

Abstract

Purpose: To determine the effect of a RT program on IGF-1, muscle strength, physical function and cognitions in Costa Rican female older adults. Methods: Twenty-six older adults were randomly assigned to a control (CTRL, n = 14, age = 68.8 ± 3.7 yr.) or experimental (EXP, n = 12, age = 69.3 ± 2.5 yr.) group. Both groups attended the exercise sessions two times/week, 40-min/session, for 8 weeks. The CTRL group performed slow-motion stretching exercises, and the EXP group performed RT exercises at 70% of 8-RM. Pre- to post-measurements were obtained on IGF-1, muscle strength, the 30-s chair-rise test, and short-term memory, working memory, psychomotor speed, attention and mental flexibility. Mean differences were studied by mixed 2 (groups) x 2 (measurements) ANOVA. Tukey’s post-hoc tests followed significant ANOVA interactions. Results: IGF-1 increased in EXP (Pre= 161.0 ± 55.6 vs. Post= 205.3 ± 49.3 ng/mL) and CTRL (Pre= 128.6 ± 51.5 vs. Post = 174.9 ± 70.7 ng/mL) groups (p < 0.05). Significant improvements (p < 0.05 for all) were found in leg extension (EXP= 52.3 ± 9.4 vs. CTRL= 47.9 ± 8.6 kg), chest press (EXP= 52.3 ± 16.1 vs. CTRL= 42.6 ± 9.1 kg), hip adduction (EXP= 47.1 ± 12.8 vs. CTRL= 37.8 ± 6.7 kg), back strength (EXP= 45.5 ± 10.4 vs. CTRL= 39.4 ± 4.6 kg), 30-s chair test performance (EXP= 14.8 ± 1.3 vs. CTRL= 10.3 ± 1.8 rep/30-s), and mental flexibility (EXP= 143.0 ± 16.6 vs. CTRL= 142.1 ± 16.4 s). Conclusion: A RT program improved muscle strength, physical function, and mental flexibility in female older adults compared to an active control group. The positive change in mental flexibility is a relevant finding due to the small number of studies in older adults. The increase in IGF-1 in both groups following eight weeks of physical activity and training are beneficial for older adults due to the proven importance of growth factors for brain health.