Hemodynamic and Autonomic Modulation in Response to Additive Sympathetic Stressors in Young, Healthy Individuals

Isometric handgrip (IHG) coupled with post-exercise muscular ischemia (PEMI) and the cold pressor test (CPT) have been demonstrated to increase measures of hemodynamics and to reduce vagal tone. However, little is known about how acute resistance exercise (RE) alters these responses. The purpose was to evaluate an acute bout of RE in conjunction with a single- or dual-stressor task on hemodynamics and autonomic modulation in resistance-trained individuals. Ten resistance-trained individuals (Mean ± SD; Age: 23 ± 3 years) completed a single-(SS: IHG + PEMI only) or dual-stressor (DS: IHG + PEMI + CPT) task condition. Before and after the acute RE variables were monitored during five minutes of rest (REST), two minutes of IHG, three minutes of PEMI with or without concurrent CPT (STRESS). Hemodynamics included heart rate (HR), mean arterial pressure (MAP), cardiac output (Q,). stroke volume (SV) and total peripheral resistance (TPR), while autonomic data were measured via heart rate variability and heart rate complexity. There were no significant (p > 0.05) three-way interactions for HR, Q, or TPR. However, there was a significant three-way interaction (p = 0.007) for SV such that SV was significantly increased during STRESS compared to REST in the SS condition but did not change in the DS condition. There were no significant (p > 0.05) interactions for measures of autonomic modulation. These data suggest that young, resistance-trained individuals have a significant cardiac sympathetic reserve and thus a large capacity to handle multiple stressors following acute RE.