Potential Therapeutic Utility of Hypoxic‐Exercise Training Among Obese Breast Cancer Survivors with Limited Mobility: Pilot/Feasibility Study
Authors: Carter Stephen J. , Hunter Gary R. , Norian Lyse A. , Rogers Laura Q. 
Published: June 2021

ObjectiveObesity and lower‐extremity dysfunction are common comorbidities that may contribute to the prevalence of insufficient physical activity among breast cancer survivors (BCS). To mitigate the biomechanical strain associated with treadmill exercise, we evaluated the feasibility of 8 weeks of hypoxic‐exercise training (HYP) compared to normoxic‐exercise training (NOR) among a cohort of BCS with limited mobility.MethodsTen (n = 10) post‐primary treatment BCS with a body mass index between 30–45 kg/m2 and a preferred walking speed < 1.3 m·s−1 were enrolled in a two‐arm randomized control design. Following baseline assessments, participants were assigned to supervised exercise training (3×/week) in HYP (FiO2 16%) or NOR (21% FiO2) conditions, matched for relative‐intensity. Dual‐energy X‐ray absorptiometry was used to estimate %body fat. A graded exercise test consistent with the modified‐Naughton protocol was used to measure peak oxygen uptake (V̇O2). A 2‐stage treadmill task (0.89 m·s−1) of non‐graded and graded (2.5%) walking was used to examine acute physiologic responses (e.g., heart rate and blood pressure) to submaximal exercise. Follow‐up assessments were performed within five days of completing the final exercise training session. Between‐group comparisons were calculated as a percent change from baseline. Substantive differences were determined by Hedges' g as a measure of effect size.ResultsFour and five participants completed the exercise training in the HYP and NOR groups, respectively. The HYP group achieved 100% of the prescribed exercise whereas the NOR achieved 96%. The HYP group had one dropout due to a work‐schedule shift, however; no adverse events were reported in either group throughout 8 weeks of exercise training. Changes in %body fat, though not statistically significant, tended to differ (HYP −1.3 ± 2.5% vs. NOR +0.4 ± 1.0%; p = 0.21; g = 0.94) between‐groups. Similar percent changes in peak V̇O2 were observed (HYP +6.6 ± 3.3% vs. NOR +5.9 ± 10.7%; p = 0.89; g = 0.09) between‐groups. Changes in systolic blood pressure tended to differ during non‐graded (HYP −10.2 ± 3.9% vs. NOR −2.0 ± 4.7%; p = 0.03; g = 1.8) and graded (HYP −9.2 ± 4.3% vs. NOR −1.8 ± 8.1%; p = 0.15; g = 1.1) treadmill walking.ConclusionsTo our knowledge, this is the first study to evaluate HYP exercise training among a population with a history of cancer. Feasibility results suggest HYP exercise training is well‐tolerated and does not impose any increased risk of adverse events compared to NOR exercise training among BCS. In the presence of obesity and/or lower‐extremity dysfunction, HYP exercise training may be an effective strategy to elicit favorable physiologic adaptation at a reduced absolute workload and consequent biomechanical strain.Support or Funding InformationNIH R25CA047888 and P30DK056336; UAB Palliative Research Enhancement ProjectThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.