Heart Rate Variability and Cardiovascular Adaptations Among Cancer-Survivors Following a 26-Week Exercise...

Cardiotoxicity as a result of cancer treatment contributes to autonomic dysfunction and decreased cardiorespiratory fitness among cancer survivors. These deleterious cardiovascular outcomes reduce the survival prognosis for cancer patients and contribute to poor quality of life among survivors. Exercise interventions have been shown as effective in mitigating treatment-related side effects. However, previously published interventions have not explored the potential for improvement in autonomic dysfunction (heart rate variability, HRV). This study examined cardiovascular adaptations in cancer survivors (n = 76) who participated in a 26-week intervention consisting of combined aerobic and resistance training (CART). The most noteworthy improvements occurred during the first 13 weeks of training and were maintained throughout the end of the 26-week period. HR_rest improved from baseline (PRE) to the midpoint (MID) (P = .036) and from PRE to POST timepoints (P = .029). HRV and VO_2max did not initially appear to change in response to CART. However, after stratification on time since treatment, participants who were 5 or more years from their last treatment experienced improvements (ie increase) in the HRV characteristic of HF power (P = .050) and also in VO_2max (P =.043), when compared to those experiencing less than 5 years of time since their last treatment. These findings highlight a need for more attention to address the cardiorespiratory deficits experienced by those who have recently completed cancer treatment. In conclusion, the CART intervention is effective in improving cardiorespiratory fitness and autonomic dysfunction. The structure of the intervention is feasible for cancer survivors to continue with at home, using minimal resources, and without supervision. This at-home model may be even more acceptable to recent survivors that may be homebound immediately following treatment.