Heart Rate Variability in Cancer Survivors Post 13-Week Exercise Intervention

Aerobic and resistance exercises have been shown to enhance autonomic control of the heart.  Certain cancer treatments cause cardiotoxicity, negatively affecting the autonomic function and contributing to increased incidence of cardiovascular events in cancer survivors.  The purpose of this study was to examine the effects of a 13-week training exercise program on the cardiac autonomic function measured by HRV.  Methods: POLAR RS800CX heart-rate-monitors were used to assess HRV at baseline and post-intervention in eighteen cancer survivors (n=14 (women), n=4 (men)).  Participants laid supine in a quiet environment free of sensory stimulation.  Breath was paced at 12 breaths per minute by using a metronome.  For 13 weeks, participants engaged in aerobic and resistance circuit-training exercises three times per week for an hour.  Attendance was recorded.  Results: The data was downloaded and interpreted using the Polar and Kubios Software systems.  HRV was divided into the following spectral powers: Low Frequency (LF), High Frequency (HF), and Total Percent Power (LF/HF).  Paired sample t-test yielded the following results: LF (p=0.034), HF (p=0.602), and LF/HF (p=0.033).  Correlation between percent change in LF, HF, and LF/HF with attendance was r=0.17, r=0.43, and r=-0.27, respectively.  Conclusions: Statistically significant results for LF and LF/HF ratio indicate that there is a decrease in overall sympathetic control.  There is also a moderate correlation between attendance and HF, which indicates that there is a higher likelihood of increased parasympathetic control in cancer survivors who exercise more often.  These results suggest that short exercise intervention can improve cancer survivor’s cardiac autonomic control.