[Short-term exercise-based cardiac rehabilitation induced changes in cardiorespiratory, mechanical and neuromuscular responses to progressive exercise testing]. / Dissociation des réponses cardiorespiratoires et neuromusculaires à l'exercice à la suite de 4 semaines de réentraînement à l'effort chez des patients cardiaques.

Previous studies showed that changes in peak of oxygen uptake value (VO2peak) with training were poorly related to changes in Maximal Tolerated Power output (MTP) among patients with cardiovascular disease. This result could be due to a difference between cardiopulmonary adaptation to training and the skeletal muscle conditioning. OBJECTIVE: The aim of the study was to compare the responses to exercise training of electromyographic activities of vastus lateralis (rms-EMG) and respiratory parameters. METHODS: Nine cardiac patients (64.0±3.1y, 172.9±4.8cm, 83.4±16.3kg, BMI: 27.8±4.5) performed an incremental cycling exercise test to determine MTP, VO2peak and peak values of heart rate, before and after an aerobic training. Ventilatory thresholds were respectively determined as the breakpoint in the curve of carbon dioxide output against oxygen uptake plot (VT1) and the point at which the ratio of minute ventilation to carbon dioxide output starts to increase (VT2). EMGth1 and EMGth2 were defined as the first and the second breakpoints in the rms-EMG - power output relationship. RESULTS: Short-term exercise training (23.7±8.8 days) induced a significant increase in VO2peak (P=0.004), MTP (P=0.015), VT1 (P=0.001) and VT2 (P=0.001). Changes in VO2peak only attained the survival criteria (3.5±2.9mLmin-1kg-1). No significant differences (P>0.05) existed between mean power values of VT1 and EMGth1 (60.5±4.1 vs. 59.2±9.6% of MTP, respectively), or between VT2 and EMGth2 (78.3±5.7 vs. 80.2±5.2% of MTP). After training, EMGth1 occurred significantly before VT1 (60.5±6.2 vs. 64.8±4.8% of MTP, P=0.049). CONCLUSION: This might be taken into account for prescribing exercise rehabilitation according initial clinical limitations of patients.

Exercise-based Cardiac Rehabilitation in Coronary Disease: Training Impulse or Modalities?

To compare the effects of 2 short programs with similar training load (TL), based on combined aerobic - resistance training (CT) or aerobic training (AT) on cardiorespiratory responses, 32 patients with coronary heart disease (CHD: 63.8±8.0y, 1.73±0.06 m, 84.8±15.9 kg, Left Ventricular Ejection Fraction: 0.53±0.8) performed 4 weeks of exercise rehabilitation based on CT (n=16) or AT (n=16). Maximal tolerated power (MTP), peak values of oxygen uptake (VO2peak) and heart rate (HRpeak), anaerobic threshold (VT1) were determined during an incremental cycling exercise test before and after training periods. TL, quantified using the session rating of perceived exertion, did not differ between both modalities (CT: 4 438±572 vs. AT: 4 346±592 AU, p=0.300). Improvements in VO2peak were larger after CT (+36.4±24.7% of pre-training VO2peak, i. e., +4.4±2.3 mL.min-1.kg-1, n=14) than observed after AT (+20.1±9.1% of pre-training VO2peak, i. e., +2.6±1.0 mL.min-1.kg-1, n=12) (p=0.014). Additionally, CT significantly improved power (54.6±23.8 vs. 75.1±21.2 watts, p=0.001) and VO2 associated at VT1 (VO2: 9.8±2.5 vs. 12.6±2.9 mL.min-1.kg-1, p=0.001). This might be taken into account when prescribing exercise rehabilitation for CHD patients with different initial clinical limitations.

[Is there a disassociation of ventilatory and electromyographic thresholds in patients with heart disease during a graded cycling exercise?] / Concordance et dissociation des seuils de fatigue électromyographiques et des seuils ventilatoires chez le patient en réadaptation cardiaque.

Exercise prescription was generally based on the determination of ventilatory thresholds (VT1, VT2) during cardiopulmonary exercise testing (CPX). Changes in surface electromyographic activity (EMGth1, EMGth2) were also related to VT1 and VT2 in healthy subjects. OBJECTIVE: To observe the occurrence of EMGth1 and EMGth2 and whether these events accompany VT1 and VT2 during CPX in cardiac patients (CP). METHOD: Thirty-four CP (62.1±7.3years, 172.1±6.3cm, 81.3±15.3kg, BMI: 27.3±4.1) performed a cycle CPX at a 60-rpm cadence. VT1 was determined as the breakpoint in the curve of carbon dioxide output against oxygen uptake plot (V-slope method). VT2 was defined as the point at which the ratio of minute ventilation to carbon dioxide output starts to increase. The root mean square of electromyogram (rms-EMG) was on-line calculated from the real time bipolar surface electromyographic signals recorded from the vastus lateralis. EMGth1 and EMGth2 were defined as the first and the second breakpoints in the rms-EMG-power output relationship. RESULTS: Peak values of oxygen uptake (16.3±4.6mL·min-1·kg-1) and heart rate (106.7±13.8bpm) were reached at 112.9±38.5w (PMT). VT1 and VT2 occurred at 71.1±25.9w (62.5±5.5% PMT) and 87.9±28.6w (78.0±5.1% PMT). All subjects presented two breakpoints in the rms-EMG curve, EMGth1 at 68.0±24.7w and EMGth2 at 88.5±30.1w, i.e. 60.0±7.6 and 78.6±5.0% of PMT. EMGth1 occurred significantly before VT1 (P=0.004, small effect size). No significant difference was observed between EMGth2 and VT2 (P=0.13, small effect size). CONCLUSION: The EMGth1 occurrence before VT1 suggested a role of skeletal muscle conditioning on ventilatory responses, which should be taken into account in cardiac rehabilitation program prescription.

Comparison of 2 portable respiratory gas analysers.

The aim of this study was to compare respiratory measures taken simultaneously using the Cosmed K4b(2) and Cortex Metamax II portable metabolic systems. 10 trained male cyclists performed a graded exercise cycle test to exhaustion (40w.3 min (- 1)) under standardized conditions. The measured respiratory variables were significantly correlated between both devices: r=0.97 and 0.98 (n=10, p<0.01) for oxygen uptake ( V˙O(2)) and ventilation (VE), respectively. Further Bland and Altman plots revealed a good level of agreement for measures of V˙O(2) expressed in mL.min (- 1) [- 670 to 486] (mean bias of - 91.7, i. e., - 3.1%) or in mL.min (- 1).kg (- 1) [- 7.3 to 9.0] (mean bias of 0.85, i. e., 2.3%) and V(E) [- 23.1 to 18.2] (L.min (- 1), mean bias of - 2.4, i. e. - 4.1%). However, poor agreement was found for measures of carbon dioxide (VCO(2), mL.min (- 1)) [- 280 to 1 394] (mean bias of 671 i.e., 20.3%). VCO(2) at maximal exercise intensity was also significantly (p<0.01) greater in the Cortex compared to the Cosmed system. The higher measured CO(2) concentrations led to significantly (p<0.01) higher calculated respiratory exchange ratio (RER) values with the Cortex device. In conclusion, there was satisfactory agreement between the Cosmed K4b(2) and Cortex Metamax II systems for most respiratory measures; however there was a poor level of agreement between VCO(2) and calculated RER measurements between the 2 systems.

Physiological responses in handcycling. Preliminary study.

INTRODUCTION: In the field of sports for the disabled, this last decade has been marked by the development of handcycling. Although assessment of maximal capacity during arm exercises in cases of spinal cord injury (SCI) has been widely investigated, investigations of maximal capacity in handcyclists remain less frequent. OBJECTIVE: The aim of this study was to investigate the physiological parameters of an incomplete quadriplegic athlete (cervical lesion C5-C6; ASIA-D) during an adapted incremental handcycling test and to judge the appropriateness of the test. Using such a test, it will then be possible to determine the individualized training program intensity needed to improve the athlete's aerobic capacity. METHODS: The athlete completed an incremental hand cycling test (i.e., an adapted Léger-Boucher test), with the handbike mounted on an ergotrainer. The athlete's physiological parameters were recorded during the test, and the pedalling rate and the perceived exertion rate were estimated. Given the athlete's pathology, ergonomic adaptations were necessary in order to improve comfort and propulsion quality. RESULTS: The maximum values recorded (VO2peak = 1.16l/min; [La]=7.7 mmol/l; heart rate peak=133 beats/min; maximum respiratory frequency=85 cycles/min and averaged pedaling rate=95 tours/min) indicate that the incremental test, adapted for handcycling, is maximal, and consequently, it should be possible to individualize the training intensity. CONCLUSION: This test is innovative and potentially applicable in a booming discipline garnering more and more interest. However, first it is necessary to extend this test to a larger population and to test the extended application in field.

[One-leg cycling aerobic training with the healthy leg in amateur soccer players after anterior cruciate ligament reconstruction]. / Entraînement en endurance à partir du membre inférieur sain chez des footballeurs amateurs opérés de ligamentoplastie de genou.

OBJECTIVE: To examine cardiorespiratory fitness changes in subjects having undergone knee surgery and to assess the benefits of one-leg cycling aerobic training program during the rehabilitation period. METHOD: Two groups of 12 patients took part in this study. The control group profited from a five weeks conventional rehabilitation in day hospital without cardiorespiratory training. The second group profited in supplement from a one-leg cycling aerobic training program with the valid leg. The subjects were trained for 21 min, by alternating 3 min at 70% and 3 min at 85% of VO(2 peak). They totaled 15 sessions spread over five weeks. The initial evaluation (T1) is carried out the first day of rehabilitation and the final evaluation (T2) at a distance within 35 days. The evaluation consisted in realizing a maximal graded tests starting from the valid leg. RESULTS: After five weeks of conventional rehabilitation, we record a reduction of peak power output (W(peak)), peak oxygen uptake (VO(2 peak)) and peak minute ventilation (VE(peak)), respectively of 11, 12 and 13% for the control group. On the other hand, in T2, the training group has on average identical maximum values and some of them increased (W(peak): +14%; VE(peak): +15%). The first and second ventilatory thresholds appear with higher intensities of exercises. CONCLUSION: After knee surgery, conventional rehabilitation does not limit cardiorespiratory deconditioning. One leg cycling appears to be an adapted method to stop the effects of hypoactivity.

[Preliminary study of cardiorespiratory decondittioning in athletes after anterior cruciate ligament reconstruction]. / Etude préliminaire de la désadaptation cardiorespiratoire après une ligamentoplastie de genou chez le sportif.

AIM: The aim of this study was to analyze changes in cardiorespiratory fitness of athletes who had surgery following a lesion of the anterior cruciate ligament of the knee. METHODS: Two groups of 12 athletes at the regional level underwent surgical repair to rebuild the external anterior crossed ligament of the knee (central third bone patellar tendon bone autograft and doubled semitendinosus/doubled gracilis autograft techniques). All subjects were evaluated before and after surgery within 7 days: the first group underwent maximal incremental tests with the upper limbs, and the second group measurement of resting cardiac volumes. RESULTS: Surgery followed by a few days of confinement generated a quick and significant reduction in the maximal oxygen consumption (-7%, P<0.05) and peak aerobic power (-8%, P<0.05). End diastolic volume and stroke volume were reduced, by 23% and 27% respectively (P<0.05). A significant reduction of ejection fraction was also observed (P<0.05). The mean left ventricular ejection fraction was 65% before the surgery 60% after 7 days' of hospitalization. CONCLUSION: In sportsmen, 7 days of hospitalization due to surgery of the knee led to resting cardiac unsuitability characterized by a significant reduction in the stroke volume. These elements could involve decreased aerobic fitness and should encourage the hospital practitioner to propose a program of aerobic training in addition to conventional rehabilitation.

Spontaneously chosen crank rate variations in submaximal arm exercise with inexperienced subjects. Effects on cardiorespiratory and efficiency parameters.

The aim of the present study was to compare the physiological responses during arm exercises when the crank rate was chosen spontaneously (TS) or set at +/- 20 % (T-20, T+ 20) of the spontaneously chosen crank rate (SCCR). Eight physical education male students, aged 22 +/- 3.2 years, performed an upper body exercise in which intensities ranged from unload to 80 % of maximal power. No significant difference was observed in oxygen uptake, ventilation, gross and net efficiency values between TS and T+ 20 or T-20. Nevertheless, oxygen uptake and ventilation were significantly (p < 0.05) lower and gross and net efficiencies higher (p < 0.05) during T-20 than T+ 20. No significant difference was noticed for heart rate, delta and work efficiency between TS, T-20 and T+ 20. The hypothesis that SCCR is the most economical one according to the efficiency parameters was not quite verified. However, crank rates lower than SCCR could be interesting because they increase gross efficiency compared to higher crank rates. Moreover, the selection of crank rates depends on power output. Indeed, SCCR increased significantly (p < 0.05) with power output. In the physical reconditioning of injured or handicapped subjects, the latter are very sensitive to the power output, and the crank rate could be another constraint.

Physiological effects of variations in spontaneously chosen crank rate during sub-maximal and supra-maximal upper body exercises.

The aim of the present study was to compare the physiological responses when the crank rate was chosen spontaneously (Ts) or set at +/- 10% (T-10%, T+10%) of the freely chosen rate, during two upper body exercises: i) a sub-maximal test (T(SUB)) in which intensities ranged from 50 to 80% (118.4 +/- 10.2 to 189.5 +/- 16.3 watts) of maximal power (MP) and ii) a supramaximal test (T(SUPRA)) in which power output was set at 110 and 120% (260.5 +/- 22.4 and 284.2 +/- 24.4 watts) of MP. Eight nationally and internationally ranked kayakers, aged 20 +/- 2 years, performed these tests in which power outputs were normalised in relation to the maximal power output determined during T(MP). In T(SUB+10%), oxygen uptake and ventilation were significantly (P< 0.05) higher than during T(SUBxS). In T(SUB+10%) and T(SUB-10%), energy expenditure was significantly (P<0.05) higher and gross and net efficiencies lower than during T(SUBxS). During T(SUPRA-10%) when the power output was set at 110% of MP, time to exhaustion was significantly higher (P<0.05) than during T(SUPRAxS). The findings of the present study suggest that upper body exercise performed on an ergocycle should be conducted using the freely and spontaneously chosen crank rate.

Relationship in humans between spontaneously chosen crank rate and power output during upper body exercise at different levels of intensity.

The aim of this study was to assess the relationship between spontaneously chosen crank rate (SCCR) and power output during two upper body exercise tests: firstly, an incremental maximal aerobic power test (T1), with an initial intensity of 50 W followed by 15-W increases at each subsequent 90-s stage and secondly, a test (T2) with consecutive exercise periods set at 50%, 60%, 70%, 80%, 110% and 120% of maximal power (Pmax) separated by passive recovery periods. Eight nationally and internationally ranked kayakers, aged 20 (SD 2) years, performed the tests. During both T1 and T2, mean SCCR values were correlated (r = 1) and increased significantly (P < 0.05) in association with the increases in power output. The finding that the subjects consistently increased their crank rate as the power output increased in different tests, i.e. at submaximal, maximal and supramaximal intensities, strongly suggests that SCCR depended on power output and not on the type of exercise (incremental or rectangular exercise). Moreover, the equation relating crank rate and power output determined from T1 suggests that it may be used to predict the crank rate which will be chosen in upper body exercise, whatever the intensity. Finally, the results of testing at 110% and 120% of Pmax would suggest that a high crank rate (>90 rpm) should be used during the test procedure using supramaximal exercises where accumulated oxygen deficit is calculated, and more particularly when exercise is performed using the upper body.

Physiological effects of variations in spontaneously chosen crank rate during incremental upper-body exercise.

The aims of the present study were: first, to assess the interindividual variations of a spontaneously chosen crank rate (SCCR) in relation to the power developed during an incremental upper body exercise on an arm ergometer set at a constant power regime, and second, to compare heart rate (HR) responses, expired minute ventilation (V[E]) and oxygen consumption (VO2) when the pedal rates were chosen spontaneously (T[SCCR]) or set at +/- 10% of the freely chosen rates (T[+10%] and T[-10%], respectively). The mean pedal rate values were linearly related (P < 0.01) with the power developed during arm cranking (r = 0.96), although large variations of pedalling rate strategies were observed between subjects. Maximal power (MP) and time to exhaustion values were significantly higher (P < 0.05) during T(SCCR) than during T(+10%) and T(-10%). Peak VO2 values were significantly higher (P < 0.05) in T(+10%) than in T(SCCR) and T(-10%). The increase in HR, V(E), and VO2 mean values, in relation to the increase in the power developed, was significantly higher (P < 0.05) when the pedal rate was set at plus 10% of the SCCR (T[+/-10%]) than in the two other conditions. The findings of the present study suggest that the use of an electromagnetically braked ergometer, which automatically adjusts the resistance component to maintain a constant work rate, should be used in order to achieve the highest MP values during an incremental upper body exercise. A 10% increase of the SCCR should be used in order to provide the highest peak VO2 value.