Hemodynamic responses following dynamic resistance exercise in young and older adult women

This investigation examined the effects of age, exercise and test condition on hemodynamic variables, autonomic and vascular function in relation to resistance exercise (RE). The associations among these variables were also examined. METHODS: Sixteen young (21.4+1.4 yrs) and 16 older (69.7+3.9 yrs) women performed 5- and 15- repetition maximal (RM) of knee extension RE. Continuous blood pressure (BP) and electrocardiography (ECG) data were recorded. The dependent variables are reported at pre-exercise, peak exercise and recovery period. Heart rate variability data were derived from 5- and 10-min segments before and after exercise. Resting and after arterial occlusion forearm vascular function indices and pre- and post-exercise resting forearm blood flow and forearm vascular resistance (FVR) were measured using plethysmography technique. ANOVA with repeated measures was used for statistical analysis. LSD was used where post hoc comparison required. Pearson correlation and linear regression were used to examine associations between autonomic and vascular function indices and hemodynamic parameters; alpha=0.05. RESULTS: Resistance exercise resulted in increased BP (SBP=36.6+2.2; DBP=27.4+1.6 mmHg) and HR (37.8+1.6 beat/min). This was followed by a drop in BP below pre-exercise level throughout the recovery period up to 60 minutes. The 15-RM condition resulted in higher SBP at peak exercise (15-RM: 155.7+3.7 vs. 5-RM: 142.3+3.7 mmHg) and in the early phase of recovery (local min: 15-RM=127.0+2.7 vs. 5-RM=120.4+2.6 mmHg); however, the 5-RM condition resulted in greater 1-min and 3-min post-exercise SBP recovery ratios (15-RM: 1-min=0.78+0.01; 3-min=0.76+0.01 vs. 5-RM: 1-min=0.84+0.01; 3-min=0.82+0.01). Older women had higher SBP throughout the testing period, and higher 1-min and 3-min recovery ratios (Young: 1-min=0.80+0.01; 3-min=0.78+0.01 vs. Old: 1-min=0.83+0.01; 3-min=0.80+0.01). However, the older women experienced greater drops in BP (SBP: young=-0.02+2.6 vs. old=-9.4+2.3; DBP: young=-3.5+1.8 vs. old=-9.8+1.9 mmHg) during the recovery period. FVR after RE increased above pre-exercise only in the young (p\u3c0.03). Low-frequency variations in HR were related to recovery of mean arterial pressure (young: r=0.66, p\u3c0.001; older: r=0.79; p\u3c0.001) and FVR (young: r=0.93, p=0.001; old: r=0.95; p\u3c0.001). CONCUSION: Age-group differences in post-exercise BP drop, characterized by a greater decline in BP in older adults, might be attributed to smaller increases in vascular resistance in older women