The Impact of Isometric Handgrip Training on Cardiovascular Stress Reactivity: Does Baseline Psychological Stress Matter?

Abstract

Cardiovascular stress reactivity (CSR) is associated with cardiovascular risk factors such as hypertension and carotid intima media thickness. It may also be influenced by baseline perceived psychological stress. Isometric handgrip training (IHGT) has been shown to reduce CSR in hypertensive adults, however, the impact of IHGT on CSR in normotensive adults is unknown. PURPOSE: To examine the effect of IHGT on CSR in young, healthy males and to assess the potential influence of variability in baseline perceived stress across the intervention. METHODS: Young, healthy male subjects were randomly assigned to a control (n=11, 22±4 yrs) or IHGT group (n=11, 23±4 yrs). The Perceived Stress Scale (PSS) was administered and mean arterial pressure (MAP) was assessed during the Trier Social Stress Task. CSR was calculated as the difference in MAP from baseline to peak during stress. A single training session consisted of 4 alternating right and left 2 min isometric handgrip contractions (30% maximal voluntary contraction) and this was performed 5 days/week for 5 weeks. All measurements were performed before and after the intervention. RESULTS: There was a significant reduction in CSR post-intervention (19±10 vs. 23±11 mmHg, p<0.02) however, this was not significantly different between groups (p=0.45). PSS score did not change with the intervention (14±7 vs. 13±6 p=0.56) or differ between groups (p=0.7). Overall, CSR did not correlate with PSS scores (r2= -0.03, p>0.2) and addition of the PSS score to CSR analysis did not alter the findings. However, there was a significant negative correlation between CSR and PSS scores of less than 15 (r2= -0.3, p<0.001). Addition of PSS score to CSR analysis in only these participants did not show a training reduction of CSR compared to the control group (28±3 vs. 19±3 mmHg; 20±3 vs. 18±3 mmHg, p=0.172). CONCLUSION: In contrast to some findings with aerobic training, IHGT did not lower CSR in young, healthy males. Lower responses overall post intervention suggest that some habituation to the TSST occurred. Although considering PSS score did not alter current findings, CSR decreased with increasing reported stress up to a moderate reported stress level (PSS score of 15). This suggests that considering baseline levels of stress may be helpful in interpreting CSR changes with exercise interventions.