Resistance Training Adaptations in Young and Older Women

Abstract

Resistance Training is an important intervention for preventing age-related losses in muscle mass and strength. PURPOSE: To examine age differences in muscular strength and body composition responses to resistance training in women. METHODS: Women volunteers were assigned to one of the following experimental groups: young (18-30 years) control (YC n=12); young resistance training (YR n=9); older (60-75 years) control (OC n=13); and older resistance training (OR n=25). The high intensity resistance training intervention was 15 weeks in duration with subjects performing 3 sets of 10 reps at 80% 1RM, 3 days per week for 5 lower body and 3 upper body isotonic machine-based exercises. Strength (1RM) was assessed at baseline, every 5 weeks during training for progressive overload and post-training. Total body and regional body composition was measured at baseline and after week 16 of training using DXA (GE Lunar Prodigy). RESULTS: The baseline body weights of the young groups were significantly lower p<0.05) than the older groups. Both YR and OR had significant increases (p<0.05) for all the resistance exercises and the YR exhibited significantly greater (p<0.05) strength improvements than OR except for the low row and hip extension exercises. Relative changes in strength ranged from 23.5% (shoulder press) to 74.4% (hip adduction) in YR and from 13.1% (low row) to 50.3% (hip adduction) in OR. There were no significant changes in total or regional % fat variables for either YR or OR. There were significant (p<0.05) group x trial interactions for arm and total body bone free lean tissue. OR had a greater increase (7.7%) in arm lean tissue than YR (4.5%) and neither control group changed for this variable (YC 0.5%, OC −3.6%). Similar increases were observed for total bone free lean tissue for the 2 training groups. There were no significant (p>0.05) changes for trunk or leg lean tissue in response to resistance training in young or older women. CONCLUSIONS: Generally, young women had greater improvements in muscle strength compared to their older counterparts. Since these strength responses were not accompanied by greater increases in lean tissue, it is possible that the young subjects had greater neural adaptations to the training than the older women.