Arterial Compliance, Brachial Endothelial Function and Blood Pressure Adaptations to Resistance Training in Young Healthy Males

Abstract

The current study evaluated the potentially detrimental effects of daily resistance training on cardiovascular health using a longitudinal study design. This study also addressed the effects of resistance training on vascular endothelial function. Recent cross-sectional studies have shown resistance trained individuals have reduced whole-body arterial compliance compared to sedentary controls and that the age-associated reduction of arterial compliance is augmented in resistance trained athletes. The effect of resistance training on vascular endothelial function has not been addressed to date in the literature. Twenty-eight young healthy males (age: 23±3.9 [mean±SD]) were whole body resistance trained five times a week for twelve weeks, using a split body design. Measurements of supine resting arterial blood pressure at the brachial artery, carotid, brachial and femoral cross-sectional compliance, and brachial vascular endothelial function (using flow-mediated dilation) were acquired prior to, halfway through and following the exercise training protocol. Strength of various body segments increased significantly following the resistance training program. Shoulder press one repetition maximum (1RM) lifts increased from 141.4±7.6 lbs. to 185.2±8.8 lbs. and double leg press 1RM from 483.0±29.0 lbs. to 859.8±52.1 lbs. Resting diastolic blood pressure increased significantly from Mid to Post training (61.8±1.3 mmHg to 65.4±1.2 mmHg) yet was not significantly changed from Pre values (62.9±1.2 mmHg). Pulse pressure was reduced significantly with exercise training by the Post training time-point (Pre 63.3±1.9 mmHg; Mid 59.0±2.4 mmHg; Post 53.7±2.8 mmHg). Mean arterial carotid and femoral artery diameters were not changed with resistance training; however, mean brachial artery diameter increased by the Mid training time-point and remained elevated at the Post training time-point (Pre 3.81±0.10 mm; Mid 4.03±0.1 0 mm; Post 4.04±0.11 mm). Cross-sectional compliance did not change at the carotid or the brachial arteries, however the femoral artery experienced a reduction of compliance by the Mid time-point that remained to the Post training time-point (Pre 0.162±0.012 mm²/mmHg; 0.125±0.013 mm²/mmHg; Post 0.129±0.015 mm²/mmHg). Brachial vascular endothelial function measured using flow-mediated dilation did not show a significant change with resistance training. When normalized for shear rate (which was also unaltered with resistance training) there were no changes in endothelial function. Peak and 1 0-s average brachial post-occlusion blood flow was enhanced with resistance training (Pre 247.5±14.0 ml/min; Mid 331.1±18.5 ml/min; Post 290.5±21.0 ml/min) possibly revealing enhanced resistance vessel function. In conclusion, resistance exercise training results decreased PP, reduced femoral compliance, an increase in mean brachial artery diameter and enhanced post-ischemic blood flow. The exact mechanisms responsible for such changes remain unknown and require further investigation.