Efficacy of a therapeutic exercise program on autonomic nervous system function, cardiac function and functional capacity in colorectal cancer survivors: a randomized controlled pilot study

Abstract

Introduction: Colorectal cancer (CRC) is one of the most frequent types of cancer in developed countries, which affects both genders, although its incidence is higher in men. For most patients with CRC, this disease has become chronic after diagnosis and treatments advances. These medical treatments, though are necessary to fight the disease, has short and long-term side effects, such as the impairment of cardiac function. These alterations have a negative impact on patients' risk of death and functional capacity and therapeutic exercise has shown to be an effective tool to reverse these side effects that treatments produce. This study aims to assess the efficacy of an 8-weeks therapeutic exercise program based on multimodal components exercises in autonomic nervous systemfunction, cardiac function and functional capacity in patients with CRC that finished their medical treatment. Methods: A randomized, controlled pilot study performed between June 2018 and February 2019. A total of 20 patients with CRC that ended their treatment (at least >1 year after the end of treatment) were randomized into 2 groups: n=10 cases and n=10 controls. Patients were derived from Virgen De las Nieves Hospital in Granada, Spain, and were assessed at the Oncology Support Unit “CUIDATE”, University of Granada, Spain by a trained physiotherapist. The therapeutic exercise program consisted of 2 sessions per week (with a rest day between sessions) for 8 weeks, including control motor, aerobic, strength and flexibility exercises. Control group received usual care. Autonomic nervous system function was assessed with Ln RMSSD and SDNN of heart rate variability (HRV); cardiac function with resting heart rate (RHR), assessed by a Norav Holter DL800 electrocardiogram monitor and functional capacity was assessed by the 6-Minute Walking Test (6MWT). Results: The intervention group obtained significantly higher values in Ln RMSSD autonomic nervous system function domain (P=0.047), and functional capacity (p=0.022); and significantly lower values in RHR (P=0.024). After the program, the intervention group increased their Ln RMSSD (mean difference=4.167 ms), decreased their RHR (61.1±10.15 bpm) and increased distance covered (499.02±74.76 m) compared to the control group: LnRMSSD (3.367), RHR (63.8±5.6 bpm) and distance covered (519.1±100.5 m). No significant difference was found in the SDNN domain of autonomic nervous system function. Conclusion: These preliminary results suggest that a therapeutic exercise program in CRC survivors may benefit some domains of autonomic nervous system function, cardiac function, and functional capacity. Further research is needed to broaden the patient sample and consolidate these findings.