Author(s): SPINELLO, G., SAMPIERI, A., CERULLO, G., CANATO, M., BONDÌ, M., BASTIN, A., MONTANARI, A., AGARAJ, P., VINDIGNI, V., BASETTO, F., CHARRIER, D., STIRCU, V., GIVRALLI, J., CASOLO, A., PAOLI, A., MORO, T., Institution: UNIVERSITY OF PADUA, Country: ITALY, Abstract-ID: 1922

INTRODUCTION:
Aging is associated with progressive skeletal muscle loss and a reduced hypertrophic response to resistance training. Muscle fiber capillarization plays a primary role in maintaining muscle size and function, and aerobic exercise is a crucial angiogenic stimulus. Resistance training remains the main driver of muscle accrual, however whether performing aerobic exercise before resistance training influences subsequent hypertrophic and strength adaptations remains unclear, and concerns regarding potential interference persist. This study investigated whether an initial aerobic pre-conditioning phase combined with upper-body resistance training could enhance subsequent resistance training-induced strength, hypertrophy, and muscle capillarization. We compared three months of resistance training alone (RG) with one month of aerobic training plus upper-body resistance training followed by two months of resistance training (AG).
METHODS:
Forty-one older adults (mean age 70.5±4.0) were randomly assigned to RG (n=19) or AG (n=22). Both groups trained three times per week for 12 weeks under supervision. RG performed progressive resistance training consisting of 3 lower body and 3 upper body exercises (3 and 2 sets, respectively) with intensity progressing from 60% to 80% of one-repetition maximum. AG conducted 4 weeks of cycling at 60% of the first ventilatory threshold plus upper body resistance exercises before performing the last 8 weeks of the same RG program. Assessment at baseline and post-intervention included isometric maximal strength test, body composition and vastus lateralis muscle biopsies. Muscle biopsy samples were analyzed for capillarization parameters and muscle fiber cross-sectional area.
RESULTS:
Muscle strength increased significantly over time in both groups (p<0.01, +24.0%). Fat mass decreased significantly over time (p<0.01, -3.2%), whereas changes in whole-body lean mass (p=0.06, +2.2%) and leg lean mass (p=0.05, +5.0%) did not reach statistical significance. No group or time x group interactions were observed for body composition variables. Analysis of muscle biopsies revealed increases in fiber cross-sectional area over time for type I (p=0.04, +18.7%), type II (p<0.01, +19.1%), and mean fiber cross-sectional area (p<0.01, +17.6%). Capillary contacts and capillary-to-fiber ratio increased significantly in type II fibers only (p<0.01).
CONCLUSION:
Aerobic pre-conditioning and resistance training alone produced comparable improvements in muscle capillarization, strength and hypertrophy. These findings indicate that an initial aerobic phase did not provide clear additive benefits for hypertrophy or strength outcomes, but also it did not impair resistance training-induced adaptations, supporting the inclusion of aerobic exercise in multicomponent training programs for older adults.