Thibaut Guiraud

High-Intensity Interval Training in Cardiac Rehabilitation

High-intensity interval training (HIIT) is frequently used in sports training. The effects on cardiorespiratory and muscle systems have led scientists to consider its application in the field of cardiovascular diseases. The objective of this review is to report the effects and interest of HIIT in patients with coronary artery disease (CAD) and heart failure (HF), as well as in persons with high cardiovascular risk. A non-systematic review of the literature in the MEDLINE database using keywords ‘exercise’, ‘high-intensity interval training’, ‘interval training’, ‘coronary artery disease’, ‘coronary heart disease’, ‘chronic heart failure’ and ‘metabolic syndrome’ was performed. We selected articles concerning basic science research, physiological research, and randomized or non-randomized interventional clinical trials published in English.To summarize, HIIT appears safe and better tolerated by patients than moderate-intensity continuous exercise (MICE). HIIT gives rise to many short- and long-term central and peripheral adaptations in these populations. In stable and selected patients, it induces substantial clinical improvements, superior to those achieved by MICE, including beneficial effects on several important prognostic factors (peak oxygen uptake, ventricular function, endothelial function), as well as improving quality of life. HIIT appears to be a safe and effective alternative for the rehabilitation of patients with CAD and HF. It may also assist in improving adherence to exercise training. Larger randomized interventional studies are now necessary to improve the indications for this therapy in different populations.

High-intensity aerobic interval training in a patient with stable angina pectoris.

Recently, high-intensity aerobic interval training was shown to be more effective than continuous moderate-intensity exercise for improving maximal aerobic capacity and endurance in patients with coronary heart disease. However, patients with exercise-induced ischemia were not included in those studies. We present the acute cardiopulmonary responses of a 67-yr-old man with stable angina pectoris during a 34-min session of high-intensity aerobic interval training. Exercise was well tolerated with neither significant arrhythmia nor elevation of cardiac troponin-T. We observed a complete disappearance of symptoms and signs of myocardial ischemia after 24 mins of exercise. This observation is similar to the warm-up angina phenomenon, an adaptation to myocardial ischemia that remains poorly understood. We conclude that high-intensity aerobic interval training is a promising mode of training for patients with stable coronary heart disease that should also be investigated further in patients with exercise-induced ischemia.

Acute responses to intermittent and continuous exercise in heart failure patients.

BACKGROUND The purpose of this study was to compare cardiopulmonary responses, exercise adherence, tolerance, and safety of optimized high-intensity interval exercise (HIIE) compared with moderate-intensity continuous exercise (MICE) in patients with heart failure and reduced ejection fraction (HFREF). METHODS Twenty patients with HFREF (aged 61 ± 9.9 years) were randomly assigned to HIIE corresponding to 2 × 8 minutes of 30-second intervals at 100% of peak power output and 30-second passive recovery intervals and to a 22-minute MICE corresponding to 60% of peak power output. Gas exchange, electrocardiogram, and blood pressure were measured continuously. Cardiac troponin T (cTnT), C-reactive protein (CRP), and brain natriuretic peptide (BNP) were measured before, 20 minutes after, and 24 hours after HIIE and MICE. RESULTS Cardiopulmonary responses did not differ between MICE and HIIE. Higher exercise adherence and efficiency were observed on HIIE with a similar perceived exertion and time spent above 90% of peak oxygen consumption compared with MICE. Neither HIIE nor MICE caused any significant arrhythmias or increased CRP, BNP, or cTnT. CONCLUSIONS Compared with MICE, HIIE demonstrated a higher exercise adherence and was well tolerated in patients with HFREF, while still providing a high-level physiological stimulus and leaving indices of inflammation (CRP), myocardial dysfunction (BNP), and myocardial necrosis (cTnT) unaffected.

High-Intensity Interval Exercise Improves Vagal Tone and Decreases Arrhythmias in Chronic Heart Failure

PURPOSE Autonomic dysfunction including sympathetic activation and vagal withdrawal has been reported in patients with chronic heart failure (CHF). We tested the hypotheses that high-intensity interval exercise (HIIE) in CHF patients would enhance vagal modulation and thus decrease arrhythmic events. METHODS Eighteen CHF patients underwent a baseline assessment (CON) and were then randomized to a single session of HIIE and to an isocaloric moderate-intensity continuous exercise (MICE). We evaluated the HR, HR variability parameters, and arrhythmic events by 24-h Holter ECG recordings after HIIE, MICE, and CON sessions. RESULTS We found that HR was significantly decreased after HIIE (68 ± 3 bpm, P < 0.01) when compared with CON and MICE values (71.1 ± 2 and 69 ± 3 bpm, respectively). HIIE led to a significant increase in normalized high-frequency power (35.95% ± 2.83% vs 31.56% ± 1.93% and 24.61% ± 2.62% for CON and MICE, respectively, P < 0.01). Both exercise conditions were associated with an increase in very low frequency power comparative to CON. After HIIE, premature ventricular contractions were significantly decreased (531 ± 338 vs 1007 ± 693 and 1671 ± 1604 for CON and MICE, respectively, P < 0.01). An association was found between the changes in premature ventricular contraction and the changes in low-frequency/high-frequency ratio (r = 0.66, P < 0.01) in patients exposed to HIIE. CONCLUSION We demonstrate that a single session of HIIE improves autonomic profile of CHF patients, leading to significant reductions of HR and arrhythmic events in a 24-h posttraining period. Cardioprotective effects of HIIE in CHF patients need to be confirmed in a larger study population and on a long-term basis.

Acute electromyostimulation Decreases Muscle Sympathetic Nerve Activity in Patients with Advanced Chronic Heart Failure (EMSICA Study)

Background Muscle passive contraction of lower limb by neuromuscular electrostimulation (NMES) is frequently used in chronic heart failure (CHF) patients but no data are available concerning its action on sympathetic activity. However, Transcutaneous Electrical Nerve Stimulation (TENS) is able to improve baroreflex in CHF. The primary aim of the present study was to investigate the acute effect of TENS and NMES compared to Sham stimulation on sympathetic overactivity as assessed by Muscle Sympathetic Nerve Activity (MSNA). Methods We performed a serie of two parallel, randomized, double blinded and sham controlled protocols in twenty-two CHF patients in New York Heart Association (NYHA) Class III. Half of them performed stimulation by TENS, and the others tested NMES. Results Compare to Sham stimulation, both TENS and NMES are able to reduce MSNA (63.5 ± 3.5 vs 69.7 ± 3.1 bursts / min, p < 0.01 after TENS and 51.6 ± 3.3 vs 56.7 ± 3.3 bursts / min, p < 0, 01 after NMES). No variation of blood pressure, heart rate or respiratory parameters was observed after stimulation. Conclusion The results suggest that sensory stimulation of lower limbs by electrical device, either TENS or NMES, could inhibit sympathetic outflow directed to legs in CHF patients. These properties could benefits CHF patients and pave the way for a new non-pharmacological approach of CHF.

Validity of a questionnaire to assess the physical activity level in coronary artery disease patients.

The aim of the study is to compare, in coronary artery disease patients, physical activity (PA) assessed with the Dijon Physical Activity Questionnaire (DPAQ) and the true PA objectively measured using an accelerometer. Seventy patients wore an accelerometer (MyWellness Key actimeter) throughout 1 week after a cardiac rehabilitation program that included therapeutic education about regular PA. Patients completed the DPAQ at the end of the week. The mean weekly active energy expenditure was 619.9±374.6 kcal, and the mean DPAQ score was 21.3±3.1/30 points. There were low but significant correlations between total active energy expenditure and the DPAQ score (&rgr;=0.4, P=0.009). There were no correlations between peak power output and total DPAQ score. The DPAQ significantly correlates with objective measures given by the MyWellness Key actimeter. The choice between these tools relies on the clinician’s appreciation, taking into account patients’ characteristics and goals as well as the cost of the method and availability of the tool.

Vo2 requirement at different displayed power outputs on five cycle ergometer models: a preliminary study

Background and aims The validity of five brands of cycle ergometers was evaluated by the comparison of the Vo2 requirements at different displayed power. Methods and results Five physically active men performed a continuous incremental exercise test on five ergometers (Ergomeca, Lifecycle, Monark, Polar S710 and CompuTrainer). The latter was also compared with a standard dynamometer in order to associate Vo2 values with the real power. Every test started with a 5-min warm-up on the same cycle ergometer (Ergomeca) at 100 W to make sure that the Vo2 differences do not come from Vo2 measurement error. Only last minute steady-state Vo2 values of each 2-min stage were used for the Vo2–watt curve. Large differences (5– 10 ml kg−1 min−1) at the same displayed power indicate inaccuracy of displayed power output (PO). Using corrected power values from the dynamometer revealed that for the same Vo2 the CompuTrainer underestimates PO by ∼30 W between 100 and 300 W, whereas the Lifecycle overestimate it by 3–53 W from 100 to 300 W. The Monark and Polar S710 underestimate PO by 15 W and the Ergomeca by ∼5 W. Conclusion Inaccuracies between −10% and 18% in displayed PO of various cycle ergometers question their interchangeability.

Improved Walking Claudication Distance with Transcutaneous Electrical Nerve Stimulation: An Old Treatment with a New Indication in Patients with Peripheral Artery Disease.

ObjectiveThe aim of this study was to determine whether 45 mins of transcutaneous electrical nerve stimulation before exercise could delay pain onset and increase walking distance in peripheral artery disease patients. DesignAfter a baseline assessment of the walking velocity that led to pain after 300 m, 15 peripheral artery disease patients underwent four exercise sessions in a random order. The patients had a 45-min transcutaneous electrical nerve stimulation session with different experimental conditions: 80 Hz, 10 Hz, sham (presence of electrodes without stimulation), or control with no electrodes, immediately followed by five walking bouts on a treadmill until pain occurred. The patients were allowed to rest for 10 mins between each bout and had no feedback concerning the walking distance achieved. ResultsTotal walking distance was significantly different between T10, T80, sham, and control (P < 0.0003). No difference was observed between T10 and T80, but T10 was different from sham and control. Sham, T10, and T80 were all different from control (P < 0.001). There was no difference between each condition for heart rate and blood pressure. ConclusionsTranscutaneous electrical nerve stimulation immediately before walking can delay pain onset and increase walking distance in patients with class II peripheral artery disease, with transcutaneous electrical nerve stimulation of 10 Hz being the most effective.

Optimization and reliability of a deep water running test in healthy adults older than 45 years.

Gayda M, Juneau M, Guiraud T, Lambert J, Nigam A: Optimization and reliability of a deep water running test in healthy adults older than 45 years. Objective:The aim of this study was to (1) compare the peak oxygen uptake across three protocols of different duration during an incremental deep water running test to exhaustion; (2) study the reproducibility of peak &OV0312;o2 during two repeated incremental deep water running tests; (3) compare peak deep water running test and treadmill cardiopulmonary responses in adults older than 45 yrs. Design:First, 24 healthy subjects older than 45 yrs (60 yrs [6 yrs], body mass index: 28 kg/m2 [6 kg/m2], 11 men/13 women) performed three incremental deep water running tests (≤8 mins, 8–12 mins, and ≥12 mins) with measurement of peak &OV0312;o2 (optimization group). Nineteen subjects of the 24 original subjects (reproducibility group) then performed two repeated maximal deep water running tests. Finally, 21 of the 24 original subjects also performed an additional maximal treadmill test (comparison group). Peak &OV0312;o2 was compared with analyses of variance for repeated measurements for the optimization, reproducibility, and comparison groups. Results:Peak &OV0312;o2 (ml/min) did not differ according to protocol duration (short: 1529 [674]; intermediate, 1456 [594]; and long, 1465 [674] ml/min, P = 0.53), was reproducible with an intraclass correlation coefficient of 0.90 (P < 0.0001), and was lower compared with treadmill (deep water running test: 1615 [586] vs. T: 2545 [511] ml/min, P < 0.0001). Conclusions:A 6- to 12-min protocol duration can be used to assess deep water running test peak &OV0312;o2, which is reproducible and lower compared with that obtained on the treadmill in healthy subjects older than 45 yrs.

Whole-Body Strength Training Using a Huber Motion Lab in Coronary Heart Disease Patients: Safety, Tolerance, Fuel Selection, and Energy Expenditure Aspects and Optimization

Objective The aim of this study was to investigate safety, tolerance, relative exercise intensity, and muscle substrate oxidation during sessions performed on a Huber Motion Lab in coronary heart disease patients. Design After an assessment of V˙o2 peak, 20 coronary heart disease patients participated in two different exercises performed in random order at 40% and 70% (W40 and W70) of the maximal isometric voluntary contraction. Results No significant arrhythmia or abnormal blood pressure responses occurred during either session, and no muscle soreness was reported within 48 hrs posttest. The authors found a difference between W40 and W70 sessions for mean (standard deviation) ventilation (25.1% [8%] and 32.1% [9%] of maximal ventilation, respectively; P = 0.04) and a small difference for mean (standard deviation) heart rate (73 [7] and 79 [8] beats/min, respectively; P < 0.01). When compared with the W40, the W70 was associated with higher active energy expenditure (2.4 [0.6] and 3.1 [0.9] Kcal/min, respectively; P < 0.0001) and a similar mean (standard deviation) oxygen uptake (5.5 [1] and 6.6 [1] ml/min per kilogram, respectively; P = 0.07). The qualitative percentages of carbohydrates and lipids oxidized were 71% and 29%, respectively, at W40 and 91% and 9%, respectively, at W70. Conclusions Both protocols, which consisted of repeating 6-sec phases of contractions with 10 secs of passive recovery on the Huber Motion Lab, seemed to be well tolerated, safe, and feasible in this group of coronary heart disease patients.