Laurent Bosquet

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.

Is heart rate a convenient tool to monitor over-reaching? A systematic review of the literature

Objective: A meta-analysis was conducted on the effect of overload training on resting HR, submaximal and maximal exercise HR (HR), and heart rate variability (HRV), to determine whether these measures can be used as valid markers of over-reaching. Methods: Six databases were searched using relevant terms and strategies. Criteria for study inclusion were: participants had to be competitive athletes, an increased training load intervention had to be used, and all necessary data to calculate effect sizes had to be available. An arbitrary limit of 2 weeks was chosen to make the distinction between short-term and long-term interventions. Dependent variables were HR and HRV (during supine rest). Standardised mean differences (SMD) in HR or HRV before and after interventions were calculated, and weighted according to the within-group heterogeneity to develop an overall effect. Results: In these competitive athletes, short-term interventions resulted in a moderate increase in both resting HR (SMD = 0.55; p = 0.01) and low frequency/high frequency ratio (SMD = 0.52; p = 0.02), and a moderate decrease in maximal HR (SMD = −0.75; p = 0.01). Long-term interventions resulted in a small decrease in HR during submaximal (SMD = −0.38; p = 0.006) and maximal exercise (SMD = −0.33; p = 0.007), without alteration of resting values. Conclusion: The small to moderate amplitude of these alterations limits their clinical usefulness, as expected differences may fall within the day-to-day variability of these markers. Consequently, correct interpretation of HR or HRV fluctuations during the training process requires the comparison with other signs and symptoms of over-reaching to be meaningful.

Acute Responses to High-Intensity Intermittent Exercise in CHD Patients

PURPOSE although the acute physiological responses to continuous exercise have been well documented in CHD patients, no previous study has examined the responses to high-intensity intermittent exercise in these patients. The purpose of this study was to compare the physiological responses to a high-intensity interval exercise (HIIE) protocol versus a moderate-intensity continuous exercise (MICE) protocol of similar energy expenditure in CHD patients. METHODS twenty patients with stable CHD (19 males and 1 female, 62 ± 11 yr) were assigned in random order to a single session of HIIE corresponding to 15-s intervals at 100% of peak power output (PPO) and 15-s passive recovery intervals and, 2 wk later, to an isocaloric MICE corresponding to 70% of PPO. RESULTS both protocols were equivalent in terms of energy expenditure. The HIIE protocol resulted in lower mean ventilation (P < 0.001) for a small difference in metabolic demand. All participants preferred the HIIE mainly because the perceived exertion measured by the Borg scale was lower (P < 0.05). No elevation of serum concentration of troponin T was found in all participants at baseline and at 20 min and 24 h after the exercise sessions, thus excluding the presence of any exercise-induced myocardial injury in our patients. CONCLUSIONS when considering physiological responses, safety, and perceived exertion, the HIIE protocol seemed to be well tolerated and more efficient in this group of stable CHD patients.

Blood lactate response to overtraining in male endurance athletes

Abstract Many physiological markers vary similarly during training and overtraining. This is the case for the blood lactate concentration ([La−]b), since a right shift of the lactate curve is to be expected in both conditions. We examined the possibility of separating the changes in training from those of overtraining by dividing [La−]b by the rating of perceived exertion ([La−]b/RPE) or by converting [La−]b into a percentage of the peak blood lactate concentration ([La−]b,peak). Ten experienced endurance athletes increased their usual amount of training by 100% within 4 weeks. An incremental test and a time trial were performed before (baseline) and after this period of overtraining, and after 2 weeks of recovery (REC). The [La−]b and RPE were measured during the recovery of each stage of the incremental test. We diagnosed overtraining in seven athletes, using both physiological and psychological criteria. We found a decrease in mean [La−]b,peak from baseline to REC [9.64 (SD 1.17), 8.16 (SD 1.31) and 7.69 (SD 1.84) mmol · l−1, for the three tests, respectively; P < 0.05] and a right shift of the lactate curve. Above 90% of maximal aerobic speed (MAS) there was a decrease of mean [La−]b/RPE from baseline to REC [at 100% of MAS of 105.41 (SD 17.48), 84.61 (SD 12.56) and 81.03 (SD 22.64) arbitrary units, in the three tests, respectively; P < 0.05), but no difference in RPE, its variability accounting for less than 25% of the variability of [La−]b/RPE (r=0.49). Consequently, [La−]b/RPE provides little additional information compared to [La−]b alone. Expressing [La−]b as a %[La−]b,peak resulted in a suppression of the right shift of the lactate curve, suggesting it was primarily the consequence of a decreased production of lactate by the muscle. Since the right shift of the curve induced by optimal training is a result of improved lactate utilization, the main difference between the two conditions is the decrease of [La−]b,peak during overtraining. We propose retaining it as a marker of overtraining for long duration events, and repeating its measurement after a sufficient period of rest to make the distinction with overreaching.

Reliability of heart rate measures used to assess post-exercise parasympathetic reactivation

Postexercise HRR (heart rate recovery) and HRV (heart rate variability) are commonly used to asses non‐invasive cardiac autonomic regulation and more particularly reactivation parasympathetic function. Unfortunately, the reliability of postexercise HRR and HRV remains poorly quantified and is still lacking. The aim of this study was to examine absolute and relative reliability of HRR and HRV indices used to assess postexercise cardiac parasympathetic reactivation.

Yo-Yo intermittent recovery test versus the Université de Montréal Track Test: relation with a high-intensity intermittent exercise.

The first purpose of this study was to determine whether the peak velocity (V(Yo-Yo)) achieved during the Yo-Yo intermittent recovery test (Yo-Yo) and the maximal aerobic velocity (MAV) determined from the Université de Montréal Track Test (UMTT) could be used interchangeably. The second purpose was to check that the V(Yo-Yo) is related to the intermittent exercise performance, which consisted of repeated 90 m distance runs in 15s performed until exhaustion, alternated with 15s of passive recovery (15/15). Fourteen amateur soccer players performed, in a random order, the 15/15 and two incremental field-tests: the Yo-Yo and the UMTT. The results of this study showed that MAV was significantly correlated to the V(Yo-Yo) (r=0.79, p<0.01). However, the error was not constant, when the V(Yo-Yo) and the MAV values were higher than 16.3 km h(-1), the MAV values tends to be higher than the V(Yo-Yo), while when the V(Yo-Yo) and the MAV values were lower than 16.3 km h(-1), the MAV values tends to be lower than the V(Yo-Yo). MAV and V(Yo-Yo) were significantly correlated to the time to exhaustion of the 15/15 (r=0.74 and r=0.72, respectively) and show that both tests are similarly related to the high-intensity intermittent exercise performance.

Effect of the lengthening of the protocol on the reliability of muscle fatigue indicators.

The aim of this study was to examine absolute and relative reliability of fatigue measures calculated from peak torque or total work during 20, 30, 40 and 50 reciprocal maximal concentric contractions performed on an isokinetic dynamometer at 180 degrees x s(-1). Eighteen moderately active men performed 50 reciprocal maximal concentric contractions on three occasions with one 7-10 days recovery between each session. Peak torque and total work were computed for each contraction and subsequently summed to compute cumulated performance after respectively 20, 30, 40 and 50 repetitions. Muscle fatigue was determined after 20, 30, 40 and 50 repetitions by the fatigue index, the percent decrease in performance and the slope. Reliability of average peak torque or average total work was similar and was not affected by the lengthening of the protocol, although a learning effect was evident for knee flexors. Reliability of fatigue measures calculated from peak torque or total work was similar, improved with the lengthening of the protocol and was better for knee extensors. Measuring average peak torque or average total work and the slope during a protocol involving 30 maximal reciprocal concentric contractions appear to represent a better compromise between reliability and physiological interpretability of the data.

Effect of Plyometric vs. Dynamic Weight Training on the Energy Cost of Running

Berryman, N, Maurel, D, and Bosquet, L. Effect of plyometric vs. dynamic weight training on the energy cost of running. J Strength Cond Res 24(7): 1818-1825, 2010-The purpose of this study is to compare the effects of 2 strength training methods on the energy cost of running (Cr). Thirty-five moderately to well-trained male endurance runners were randomly assigned to either a control group (C) or 2 intervention groups. All groups performed the same endurance-training program during an 8-week period. Intervention groups added a weekly strength training session designed to improve neuromuscular qualities. Sessions were matched for volume and intensity using either plyometric training (PT) or purely concentric contractions with added weight (dynamic weight training [DWT]). We found an interaction between time and group (p < 0.05) and an effect of time (p < 0.01) for Cr. Plyometric training induced a larger decrease of Cr (218 ± 16 to 203 ± 13 ml·kg−1·km−1) than DWT (207 ± 15 to 199 ± 12 ml·kg−1·km−1), whereas it remained unchanged in C. Pre-post changes in Cr were correlated with initial Cr (r = −0.57, p < 0.05). Peak vertical jump height (VJHpeak) increased significantly (p < 0.01) for both experimental groups (DWT = 33.4 ± 6.2 to 34.9 ± 6.1 cm, PT = 33.3 ± 4.0 to 35.3 ± 3.6 cm) but not for C. All groups showed improvements (p < 0.05) in Perf3000 (C = 711 ± 107 to 690 ± 109 seconds, DWT = 755 ± 87 to 724 ± 77 seconds, PT = 748 ± 81 to 712 ± 76 seconds). Plyometric training were more effective than DWT in improving Cr in moderately to well-trained male endurance runners showing that athletes and coaches should include explosive strength training in their practices with a particular attention on plyometric exercises. Future research is needed to establish the origin of this adaptation.

Effect of overreaching on cognitive performance and related cardiac autonomic control.

The purpose of this study was to characterize the effect of a 2‐week overload period immediately followed by a 1‐week taper period on different cognitive processes including executive and nonexecutive functions, and related heart rate variability. Eleven male endurance athletes increased their usual training volume by 100% for 2 weeks, and decreased it by 50% for 1 week. A maximal graded test, a constant speed test at 85% of peak treadmill speed, and a Stroop task with the measurement of heart rate variability were performed at each period. All participants were considered as overreached. We found a moderate increase in the overall reaction time to the three conditions of the Stroop task after the overload period (816 ± 83 vs 892 ± 117 ms, P = 0.03) followed by a return to baseline after the taper period (820 ± 119 ms, P = 0.013). We found no association between cognitive performance and cardiac parasympathetic control at baseline, and no association between changes in these measures. Our findings clearly underscore the relevance of cognitive performance in the monitoring of overreaching in endurance athletes. However, contrary to our hypothesis, we did not find any relationship between executive performance and cardiac parasympathetic control.

A Comparison of 2 Optical Timing Systems Designed to Measure Flight Time and Contact Time During Jumping and Hopping

Bosquet, L, Berryman, N, and Dupuy, O. A comparison of 2 optical timing systems designed to measure flight time and contact time during jumping and hopping. J Strength Cond Res 23(9): 2660-2665, 2009-This study was designed to investigate the interchangeability of 2 commercial optical timing systems for measuring flight time and contact time during jumping and hopping. Seventy-three physical education students (33 men and 40 women) participated in this study. They were instructed to perform 3 jump protocols (squat jump, countermovement jump, and countermovement jump free arms) and a hopping test (10 seconds with straight legs at a frequency of 2 Hz). Flight time and contact time were measured with 2 optical timing systems (Optojump, Microgate, Italia and IR-mat, Ergotest, Sweden), consisting of 2 bars placed opposite to each other. Both systems trigger a timer with a precision of 1 millisecond each time the infrared light is interrupted by the feet. Jump height was given by the systems, whereas leg stiffness was computed from contact time and flight time. Flight time was higher when measured with the IR-mat (bias ± 95% LOA [limits of agreement] = 5 ± 14 ms, p < 0.001). This difference was trivial (effect size <0.2) and clinically meaningless. The high correlation between sets of data (r = 0.99) together with narrow 95% LOA (3%) support the interchangeability of both systems to measure flight time. Similar results were found with contact time (bias ± 95% LOA = 8 ± 23 ms, p < 0.001, effect size <0.2 and r = 0.99), with the exception that it was the Optojump that provided the higher values. These trivial but significant differences between both systems had minor impact on jumping height (bias ± 95% LOA = 0.6 ± 1.7 cm, p < 0.001), effect size <0.2 and r = 0.99), and stiffness (bias ± 95% LOA = 0.8 ± 1.4 N·m−1·kg−1, p < 0.001, effect size <0.2 and r = 0.98). We concluded that both systems can be used interchangeably.