Effects of resistance training on cardiovascular responses to lower body negative pressure in the elderly

The purpose of the present study was to determine whether resistance traini ng alters the cardiovascular responses to submaximal lower body negative pr essure (LBNP) in the elderly. Twenty-one subjects were randomized into a co ntrol (C: n=10; 70 +/- 3 years, mean +/- SD) or a resistance training (TR: n=11; 67 +/- 7 years) group. Subjects in the TR underwent 12 weeks of train ing consisting of three sets of 8-12 contractions at 60-80% of their initia l maximal one repetition, three times per week, on 10 different machines. B efore (Pre) and after (Post) training, all subjects underwent exposures of LBNP of -10, -20 and -40 Torr and muscle biopsy sampling at the vastus late ralis. TR increased (P less than or equal to0.05) knee extension (Pre=379 /- 140 N, Post=534 +/- 182 N) and chest press (Pre=349 +/- 137 N, Post=480 +/- 192 N) strength. Neither body weight nor percentage body fat were alter ed (P >0.05) by training. Resistance training increased (P less than or equ al to0.05) cross-sectional area in both Type I (4203 +/- 1196 to 5248 +/- 1 728 mum(2)) and Type II (3375 +/- 1027 to 4286 +/- 1892 mum(2)) muscle fibr es. Forearm blood flow, forearm vascular conductance, mean arterial pressur e, and heart-rate responses to LBNP were not altered by the training. These data suggest that the cardiovascular responses of elderly to LBNP are unaf fected by 12 weeks of whole-body resistance training despite increases in m uscle strength and size.