Doctor of Philosophy (PhD)
The purpose was to examine the cardiovascular response to an acute bout of handgrip exercise before and after non-dominant arm exercise training. 19 people participated in 16 sessions of exercise training and 16 participants acted as controls (age: 20±1yrs). Blood flow measurements were taken at rest and following 3-min of forearm occlusion (RHBF) using plethysmography. Pneumotachometer, ECG, and blood pressure data were continuously collected during three testing conditions (spontaneous breathing (SB1: 5min), handgrip exercise (0.5hz) at 60%MVC with 50mmHg of pressure on the arm (H60+50mmHg: 5 min), and forearm occlusion (FAO: 3min)). Data were analyzed for respiratory rate, mean R-R interval, standard deviation of normal RR intervals (SDNN), normalized units of low- (0-0.15 hz) frequency power (LFnu), and mean arterial pressure (MAP). There was no main effect of group or arm. There was a main effect of test condition such that respiratory rate (+3.10±5.40breaths/min), LFnu (+19.06±14.73%), and MAP increased (+24.51±21.15mmHg) and mean R-R (-247.11±129.70msec) and SDNN (-45.16±40.65msec) decreased significantly during H60+50mmHg (non-dominant arm; p<0.05). Respiratory rate (-0.10±4.84breaths/min), SDNN (-9.50±57.14msec), and LFnu (-1.64±18.34%) recovered to SB1 levels during. Mean R-R (46.11±106.57msec) and MAP (16.65±15.84mmHg) remained elevated above SB1 (p<0.05). There were positive linear associations between forearm circumference and Mean R-R and MAP during H60+50mmHg; and MAP during FAO. There was a negative linear association with forearm circumference and Mean R-R during FAO. There was no significant main effect or interaction with handgrip exercise training on any of the variables. There was a decrease in vascular resistance during RHBF (0.80±1.08 mmHg/ ml/100ml/min, p<0.05) in the arm that underwent exercise training. In conclusion, we found elevated MAP during FAO, which is indicative of significant EPR activity during exercise. Uniquely, we found linear associations between forearm circumference and the cardiovascular response to H60+50mmHg and FAO suggesting variation in the predominant mechanism of cardiovascular control. We did not see an attenuation of cardiovascular responses to H60+50mmHg and FAO with exercise training. However, we did see a decrease in forearm vascular resistance during the reactive hyperemia condition in the exercise-trained arm.
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Kluess, Heidi A., "Vagal modulation of the heart and central hemodynamics during dynamic handgrip exercise and forearm occlusion following forearm exercise training" (2002). LSU Doctoral Dissertations. 1929.
Robert H. Wood