Background: There is a lack of international consensus regarding the prescription of high-intensity interval training (HIIT) for people with coronary artery disease (CAD) attending cardiac rehabilitation (CR). Aims: To assess the clinical effectiveness and safety of low-volume HIIT compared with moderate-intensity steady-state (MISS) exercise training for people with CAD. Methods and results: We conducted a multi-centre RCT, recruiting 382 patients from 6 outpatient CR centres. Participants were randomized to twice-weekly HIIT (n = 187) or MISS (n = 195) for 8 weeks. HIIT consisted of 10 × 1 min intervals of vigorous exercise (>85% maximum capacity) interspersed with 1 min periods of recovery. MISS was 20–40 min of moderate-intensity continuous exercise (60–80% maximum capacity). The primary outcome was the change in cardiorespiratory fitness [peak oxygen uptake (VO2 peak)] at 8 week follow-up. Secondary outcomes included cardiovascular disease risk markers, cardiac structure and function, adverse events, and health-related quality of life. At 8 weeks, VO2peak improved more with HIIT (2.37 mL.kg−1.min−1; SD, 3.11) compared with MISS (1.32 mL.kg−1.min−1; SD, 2.66). After adjusting for age, sex, and study site, the difference between arms was 1.04 mL.kg−1.min−1 (95% CI, 0.38 to 1.69; P = 0.002). Only one serious adverse event was possibly related to HIIT. Conclusions: In stable CAD, low-volume HIIT improved cardiorespiratory fitness more than MISS by a clinically meaningful margin. Low-volume HIIT is a safe, well-tolerated, and clinically effective intervention that produces short-term improvement in cardiorespiratory fitness. It should be considered by all CR programmes as an adjunct or alternative to MISS. Trial registration: ClinicalTrials.gov: NCT02784873. https://clinicaltrials.gov/ct2/show/NCT02784873.

This investigation evaluated training responses to prolonged electrical muscle stimulation (EMS) in sedentary adults. Fifteen healthy subjects (10 men, 5 women) with a sedentary lifestyle completed a 6-wk training program during which they completed an average of 29 1-h EMS sessions. The form of EMS used by the subjects was capable of eliciting a cardiovascular exercise response without loading the limbs or joints. It achieved this by means of inducing rapid, rhythmical contractions in the large leg muscles. A crossover study design was employed with subjects undergoing their habitual activity levels during the nontraining phase of the study. The training effect was evaluated by means of a treadmill test to determine peak aerobic capacity [peak oxygen consumption (V̇o₂)], a 6-min walking distance test, and measurement of body mass index (BMI) and quadriceps muscle strength. At baseline, the mean values for peak V̇o₂, 6-min walking distance, quadriceps strength, and BMI were 2.46 ± 0.57 l/min, 493.3 ± 36.8 m, 360.8 ± 108.7 N, and 26.9 ± 3.4 kg/m², respectively. After training, subjects demonstrated statistically significant improvements in all variables except BMI. Peak V̇o₂ increased by an average of 0.24 ± 0.16 l/min (P < 0.05), walking distance increased by 36.6 ± 19.7 m (P < 0.005), and quadriceps strength increased by 87.5 ± 55.9 N (P < 0.005); we did not observe a significant effect due to training on BMI (P > 0.05). These results suggest that EMS can be used in sedentary adults to improve physical fitness. It may provide a viable alternative to more conventional forms of exercise in this population.

Exercise intolerance is an important comorbidity in patients with CKD. Anaerobic threshold (AT) determines the upper limits of aerobic exercise and is a measure of cardiovascular reserve. This study investigated the prognostic capacity of AT on survival in patients with advanced CKD and the effect of kidney transplantation on survival in those with reduced cardiovascular reserve. Using cardiopulmonary exercise testing, cardiovascular reserve was evaluated in 240 patients who were waitlisted for kidney transplantation between 2008 and 2010, and patients were followed for ≤5 years. Survival time was the primary endpoint. Cumulative survival for the entire cohort was 72.6% (24 deaths), with cardiovascular events being the most common cause of death (54.2%). According to Kaplan–Meier estimates, patients with AT <40% of predicted peak VO₂ had a significantly reduced 5-year cumulative overall survival rate compared with those with AT ≥40% (P<0.001). Regarding the cohort with AT <40%, patients who underwent kidney transplantation (6 deaths) had significantly better survival compared with nontransplanted patients (17 deaths) (hazard ratio, 4.48; 95% confidence interval, 1.78 to 11.38; P=0.002). Survival did not differ significantly among patients with AT ≥40%, with one death in the nontransplanted group and no deaths in the transplanted group. In summary, this is the first prospective study to demonstrate a significant association of AT, as the objective index of cardiovascular reserve, with survival in patients with advanced CKD. High-risk patients with reduced cardiovascular reserve had a better survival rate after receiving a kidney transplant.

Background: The development of new strategies to encourage increased levels of physical activity can help to reduce the incidence of cardiovascular disease. A new system of electrical muscle stimulation (EMS) has been developed that attempts to cause an increase in energy expenditure by mimicking the action of shivering in the body. The purpose of this study was to show that this form of EMS is capable of eliciting a cardiovascular exercise response in healthy adults.Design: An observational study.Methods: Ten healthy volunteers completed a maximal treadmill test and four EMS sessions using a hand-held EMS device that delivered current to the body via five silicone rubber electrodes on each leg. At each session subjects completed 3 min stimulation at each of four stimulation outputs (10, 20, 30 and 40% of maximum output) while cardiopulmonary gas exchange and heart rate (HR) were measured. Physiological responses at increasing levels of stimulation were evaluated.Results: Average (±SD) HR and oxygen consumption (VO₂) levels of 67 ± 11 bpm and 4.7 ± 1.2 ml/kg per min at rest, respectively, were increased to 186 ± 10 bpm and 44.9 ± 9.8 ml/kg per min at peak exercise intensity on treadmill testing. The electrical stimulation was generally well tolerated by the subjects. Subjects demonstrated statistically significant increases in all physiological variables measured with successive increases in stimulation intensity. Peak HR and VO₂at 40% stimulation intensity were 101 ±12 bpm and 14.9 ± 4.3 ml/kg per min, respectively.Conclusions: These results demonstrate that this form of EMS is capable of producing a physiological response consistent with cardiovascular exercise at mild to moderate intensities. It achieves this without producing gross movement of the limbs or loading of the joints. This EMS-induced cardiovascular exercise response could be used to promote increased levels of physical activity in populations unable to participate in voluntary exercise.