Cardiovascular and musculoskeletal response to supervised exercise in patients with intermittent claudication

Abstract

Objective: Intermittent claudication occurs in 20% of the population older than 70 years, and treatment includes a supervised exercise program (SEP). Whereas there is evidence demonstrating walking improvements after an SEP, there are conflicting data on the physiologic changes behind this. This study aimed to explore and to identify the potential cardiovascular and musculoskeletal changes with exercise.

Methods: This was a single-center study at a vascular unit in England. Following written informed consent, 109 patients were recruited for an SEP, three times per week for 12 weeks. Outcome measures included walking distances, quality of life, cardiorespiratory fitness, flow-mediated dilation, and muscle strength and endurance. For normal data, paired sample t-tests were performed to compare baseline data to all time points for significance. For nonparametric data, Wilcoxon signed rank tests were performed. Significance was set at P < .05. The association between functional improvement (ie, walking distance at 3 months after the SEP) and metabolic response and patients' characteristics was determined by multivariable regressions.

Results: Maximum walking distance significantly improved from baseline by 117% at 1 week, 143% at 4 weeks, and 143% at 12 weeks after exercise. Claudication distance also significantly improved from baseline by 222% at week 1, 393% at week 4, and 452% at week 12. Quality of life significantly improved at all time points in seven of nine domains of the 36-Item Short Form Health Survey and two of five domains of the Vascular Quality of Life questionnaire. Markers of cardiorespiratory fitness significantly improved at all time points. Flow-mediated dilation demonstrated a 50% improvement, but this was not statistically significant. Muscle strength and muscle endurance significantly improved at all time points. Multivariate regression demonstrated that the ventilatory anaerobic threshold and the physical component summary score for quality of life predicted improvements in 12-week walking distance.

Conclusions: This study identified that the ventilatory anaerobic threshold and physical component summary scores from quality of life were the best predictors of improvement in an SEP. Future studies should prioritize these outcomes and assess whether different SEPs have similar effects. Cardiorespiratory fitness was also a predictor of outcome and should be prioritized in future studies alongside traditional measures.

Trial registration: ClinicalTrials.gov NCT02641418.

Keywords: Exercise; Intermittent claudication; Mechanism.