Muscle Morphology And Body Composition Changes In Older Adults After 8 Weeks Of Resistance Training

Aging is associated with worsening functional capacity, leading to compromised physical independence and quality of life. Weight training can ameliorate functional declines; however, the specific body composition and muscle morphological adaptations thought to be responsible for these improvements are poorly characterized. PURPOSE: Determine how body composition and muscle morphology adapt following 8 weeks of resistance training. METHODS: Twenty-four older adults aged 66 ± 10 years engaged in 8 weeks of resistance training exercise, which targeted all major muscle groups during 60-minute sessions, repeated twice weekly. Participants were grouped by fall risk (High n = 8, Low n = 12) according to their 30 sec sit-to-stand performance and by age group (Young <65 yrs, n = 10, Older >65 yrs, n = 10). Pre- and post-intervention visits included Dual-energy X-ray Absorptiometry scans for lean mass (LM; g) and fat mass (FM; g) measurements. Next, vastus lateralis muscle cross-sectional area (CSA; cm2), thickness (cm), and quality (sub-cutaneous fat corrected echogenicity; CEI AU) were measured using ultrasonography. Paired samples t-tests with Bonferroni corrections were used to compare pre- vs. post-measures, while repeated measures Analysis of Variance were used to compare participants’ pre- vs. post-changes based on fall risk and age groups, α = 0.05. RESULTS: Participants decreased FM by 2.4% and improved muscle CSA, thickness, and quality (all p ≤ 0.010; d ≥ 0.63) from pre- to post-testing, as shown in Figure 1. Furthermore, participants across fall risk and age groups improved similarly (all p ≥ 0.154; η2 ≥ .06). CONCLUSION: A diverse array of participants achieved significant improvements in body composition and muscle quality in just 8 weeks. These same participants are now completing the more progressive level II to continue building upon these benefits to body composition, muscle quality, and fall risk. Supported by: This research project was funded by the Central States American College of Sports Medicine Doctoral Research Grant