Exploring the Effect of a Maximal Exercise Test on Heart Rate Variability in Young Adults

Abstract

Heart rate variability (HRV) is a commonly used tool in biobehavioral and biomedical research and may represent a non-traditional marker of disease risk. Few data exist investigating relationships between HRV and concurrent measurements of maximal exercise capacity, adiposity and heart rate recovery (HRR) in the general population. Additionally, HRV or vagal response to/and following an exercise task may independently be related to current and future health status. PURPOSE: To investigative the effects of a maximal exercise test on HRV and to explore associations between changes in HRV indices in response to exercise and fitness, adiposity and acute HRR. METHODS: As part of a larger longitudinal study, 27 young adults (Age=18-20 years, Female=48%) completed a graded maximal exercise test. HRV was assessed at two times (pre- and ~20 mins post-exercise) via an orthostatic challenge (5 min in each posture: supine, seated, standing). HRR at 2 and 4 min post-exercise was assessed as reduction in HR following exercise test cessation using the Polar RS800CX. Adiposity was measured by BodPod. HRV was processed using Kubios (v2.1, Finland). A two-way RM-ANOVA (posture*time) was used to assess the effect of maximal exercise on HRV. Spearman correlations were performed to identify associations between baseline HRV and health variables. RESULTS: Significant interactions for posture x time were seen for RMSSD (time domain) (p<0.001), approximate entropy (ApEn) (p<0.001), and baseline HR (p<0.001). Both baseline ApEn and resting HR were negatively correlated with VO2max (-0.49, p=0.009; -0.52, p=0.005, respectively) and HRR at 2 min (-0.49, p=0.009; -0.68, p<0.001, respectively). Neither baseline HRV indices nor change in HRV were related to adiposity, but changes in several HRV indices were associated with HRR and VO2max. CONCLUSION: As anticipated, maximal exercise resulted in significant posture specific changes in HRV. Continued exploration into the time-course of HRV recovery is needed, particularly as it relates to the dynamics of HRR in the initial minutes post-exercise. To interpret the potential utility of HRV measures, further investigation should focus on the relationships between HRV and traditional disease risk biomarkers in a variety of contexts. Support provided by NIMH 58144, NICHD R01 HD078346-01A1