WALKING SPEED AND WALKING PULSE: NOVEL INDICES TO QUANTIFY EFFICACY OF TRAINING IN CARDIAC SECONDARY PREVENTION

Introduction Walking is the most common form of physical activity among adults, and is widely accessible and appealing to less fit subjects. Walking Speed (WS) is a strong predictor of survival and has been considered a vital sign (Cesari, 2011). We developed a moderate 1-km treadmill-walking test (1k-TWT) to estimate peak oxygen uptake (VO2peak) in cardiac outpatients (Chiaranda, 2012). WS during a 1k-TWT predicts survival; every 1-km/h increase in WS was associated with a 40% reduction in fully-adjusted 10-year risk of all-cause mortality (Chiaranda, 2013). This study aims to examine the utility of the 1k-TWT as a measure of cardiocirculatory response to a moderate walking program. Methods Fifty-four stable coronary artery disease patients were examined at baseline and after 8 weeks of perceptually-regulated walking training (11–13/20 Borg scale). Subjects performed 20-30 min supervised treadmill walking two times/week, and two additional 20-30 min sessions of self-guided exercise/week, for 8 weeks. Training effects were assessed by the determination of VO2peak and by the ratio of walking speed to heart rate (“Walking Pulse”, WP, m/h/bpm) during the 1k-TWT. Results VO2peak increased from 24.9±5.1 to 26.4±6.3 mL/kg/min (p<0.05). WS during 1k-TWT improved from 4.4±1.2 to 5.1±1.1 km/h (p<0.0001), whereas heart rate was unchanged (93±13 vs 93±12 bpm). A 19% improvement in WP was observed after training (from 47±13 to 56±12 m/h/bpm, p<0.0001). Discussion and Conclusion Eight weeks of moderate walking substantially improved cardiocirculatory fitness in cardiac outpatients, evidenced by an improvement in both VO2peak and WP (i.e. distance covered per bpm). After training, all patients were able to walk faster at the same heart rate. By extrapolating from our earlier results on survival benefits with improved WS (Chiaranda, 2013), the 0.7 km/h improvement corresponds to a 20% reduction in long-term risk of all-cause mortality. Given the clinical implications of a slow WS, these findings underscore the concept that a short, supervised and home based moderate walking program is effective in improving outcomes in cardiac outpatients. The 1k-TWT is a simple tool to assess training responses in secondary prevention programs. WP is a new index that appears to have utility for assessing the efficacy of training. References 1. Cesari M. (2011) JAMA 305:93–4 2. Chiaranda G. et al. (2012) J Cardiopulm Rehabil Prev 32:262–9 3. Chiaranda G. et al. (2013) BMJ Open 3:e003446