Impaired oxygen uptake kinetics in the first high-level athlete with Hb Hope: a case study

Hemoglobin (Hb) Hope is a beta-globin chain variant with reduced oxygen (O₂) affinity, known to induce anemia. This usually leads to limitations in O₂uptake (VO₂) and exercise tolerance. We studied the case of a high-level female athlete with Hb Hope. She had been selected for cross-country races from 13 yrs onward, then was a national junior champion in 400-m race, and finally failed to win any cross-country races as an adult. Hematological analysis revealed normal red blood cell indices and Hb level (12.3 g.dL⁻¹). Incremental exercise showed peak work rate (WR), VO(2max) and gas exchange threshold (GET) within normal ranges for healthy females. Constant WR testing at 90% of GET showed that kinetics of pulmonary VO₂included the presence of a slow component. This was in disagreement with the data on VO₂kinetics response to exercise intensities below GET. Phase 2 parameters, time constant (τ2, 31 s), time delay (TD2, 39 s), amplitude (A2, 780 ml.min⁻¹), and gain in VO₂(ΔVO₂ .ΔWR-1, 9.2 ml.min-1.W⁻¹) were within normal ranges. Phase 3 showed a slow component similar to that reported in severe exercise. The absence of anemia and the normality of phase 2 suggested normal O₂delivery and oxidative metabolism in exercising muscles. In contrast, phase 3 suggested poor aerobic capacity and limited exercise tolerance. However, the lack of symptoms during testing also suggested that the slow component was due to the specific recruitment of fast-twitch fibers in this former champion athlete with Hb Hope in races requiring mainly anaerobic metabolism.

High plasmatic angiotensin-converting enzyme (ACE) activity is not correlated with training-induced left ventricular growth in ACE congenic rats

AIM

The aim of this study was to determine the influence of angiotensin-converting enzyme (ACE) genotype on left ventricular growth after endurance training, in ACE congenic rats with plasma ACE activity twice as high as the donor strain (LOU), thus mimicking the ACE I/D polymorphism observed in humans.

METHODS

LOU and congenic rats (n = 12) were submitted to an endurance training on a treadmill for 7 weeks, while similar LOU and congenic rats (n = 10) constituted the control groups. Blood pressure, skeletal muscle citrate synthase activity, plasma and left ventricular ACE activity were assessed, and echocardiography was performed before and after the training.

RESULTS

Angiotensin-converting enzyme plasmatic activity of congenic rats (188.2 +/- 26.6 in controls and 187.1 +/- 22.6 IU in trained rats respectively) was twofold that of the LOU strain (91.9 +/- 23.3 in controls, and 88.3 +/- 18.1 IU in trained rats respectively). After training, congenic and LOU rats showed a similar significant increase in citrate synthase activity (P < 0.05), and in the left ventricular mass/body mass ratio x 10(3): 3.7 +/- 0.3 and 3.6 +/- 0.6 in the trained congenic and LOU groups, respectively, vs. 3.0 +/- 0.1 and 2.9 +/- 0.2 in the control congenic and LOU groups respectively (P < 0.05). There was no significant correlation between ACE plasma activity and left ventricular mass in trained or untrained congenic rats.

CONCLUSION

We conclude that training-induced left ventricular growth is not associated with plasma ACE activity in congenic rats.

The performance and efficiency of cycling with a carbon fiber eccentric chainring during incremental exercise

AIM

The aim of this study was to compare cycling performance and efficiency of a carbon fiber eccentric chainring (EC) versus a metallic standard chainring (SC) during an incremental exercise. The main feature of EC was that crank-arm length changed as a function of the crank angle, being maximal during the pushing phase and minimal during the recovery one. Because of its design, cycling with EC was expected to develop higher torque during the downstroke, and lower torque during the upstroke, thus increasing mechanical efficiency and requiring lower cardioventilatory solicitation at submaximal exercise intensities.

METHODS

Eleven male subjects performed two incremental cycle tests in a randomized order using EC and SC successively. Cardioventilatory data were recorded every minute using an automated breath-by-breath system. Blood samples were taken at rest, exhaustion, 5 and 15 minutes of recovery to access lactate concentrations, [LA], mmol . L(-1) .

RESULTS

The subjects reached significantly lower maximal speed at volitional exhaustion with EC compared with SC (39.4+/-2.5 versus 41.5+/-2.9 km . h(-1), respectively; P<0.05). Analysis of variance revealed significantly higher values for oxygen uptake and carbon dioxide production during incremental exercise with EC (P<0.05). Lastly, [LA] at exhaustion were similar with the two chainrings.

CONCLUSIONS

The carbon fiber EC tested in this study failed to enhance cycling performance and efficiency throughout an incremental exercise. This indicated that carbon fibers did not exhibited its expected mechanical advantage.

Salivary IgA Response of Triathletes Participating in the French Iron Tour

Athletes are susceptible to upper respiratory tract infections (URTI) during intense training and after major competitions. Secretory IgA, which is the predominant antibody of the mucosal immune system, is the major effector of host-resistance to many microorganisms causing URTI. Previous studies have shown that salivary IgA-mediated immunity decreases after a single short distance triathlon, but the effect of repeated triathlon competitions on secretory IgA levels remains unknown. The purpose of this study was to examine the salivary IgA response of elite triathletes in repeated triathlon races during the 2001 French Iron Tour (FIT). Eight triathletes participated in this study. Saliva samples were collected daily after waking up (fasting basal state), before (pre-race) and after (post-race) each day's competition. Salivary IgA, total protein, and flow rate were measured. Salivary IgA concentrations were measured by an enzyme-linked immunosorbent assay. The salivary flow rate was significantly decreased after each race compared with the fasting basal state (p < 0.01). The salivary IgA concentration of the fasting basal state decreased over the FIT and was even lower than that of the post-race values (p < 0.05). The salivary IgA secretion rate of the fasting basal state decreased by 51.9% over the FIT (p < 0.05). Our data suggest that intense exercise repeated daily has a cumulative negative effect on basal levels of salivary IgA.

Is exercise-induced arterial hypoxemia in triathletes dependent on exercise modality?

To determine whether exercise modality affects arterial hypoxemia (EIAH) during training-intensity exercise, 13 triathletes performed 20 min of cycling (C) followed by 20 min of running (R): C-R, and two weeks later, 20 min of R followed by 20 min of C:R-C. Each trial was performed at an intensity slightly above the ventilatory threshold and close to the daily training intensity (75 % of VO2max). Ventilatory data were collected continuously using an automated breath-by-breath system. Partial pressure of oxygen in arterial blood (PaO2) was measured after each C and R segment and arterial oxyhemoglobin saturation (SpO2) was monitored continuously via pulse oximetry. The metabolic rate was similar across modalities and trials, i.e., C-R (53.8 +/- 3.8 vs. 51.1 +/- 5.3 ml.min(-1).kg(-1)) and R-C (52.2 +/- 4.5 vs. 53.2 +/- 4.6 ml.min(-1).kg (-1)). EIAH showed significantly greater severity for R compared to C irrespective of the order (p < 0.05 for both trials). R values of PaO2 (and SpO2) for C-R and R-C were 88.7 +/- 6.0 mm Hg (93.0 +/- 0.6 % SpO2) and 86.6 +/- 7.3 mm Hg (93.5 +/- 0.6 % SpO2) and C values were 93.7 +/- 8.4 mm Hg (95.4 +/- 0.4 % SpO2) and 91.4 +/- 5.4 mm Hg (94.8 +/- 0.3 % SpO2). R ventilatory data described a significantly different breathing pattern than C, with higher respiratory rate (35.9 b.min(-1) vs. 51.1 b.min(-1) for C-R, p < 0.01; and 50.0 b.min(-1) vs. 41.5 b.min(-1) for R-C, p < 0.01) and lower tidal volume (2636 ml vs. 2282 ml for C-R, p < 0.02 and 2272 ml vs. 2472 ml for R-C, p < 0.05). We concluded that EIAH was greater during running than cycling for a similar metabolic rate corresponding to training intensity and that EIAH could thus be considered dependent on exercise modality.

Non-linear analyses of heart rate variability during heavy exercise and recovery in cyclists

We investigated the time course of RR interval variability during exercise and subsequent 50 minutes of recovery in seven well-trained male cyclists who performed an exercise with 3 successive 8 min stages at 40 %, 70 % and 90 % of their maximal oxygen uptake. The goal of the study was to check whether the decrease in the amplitude of heart rate variability during heavy exercise was accompanied by changes in the chaotic structure of the fluctuations. Heart rate variability was analysed in the temporal and frequency domain using traditional tools and using non-linear methods (Largest Lyapunov Exponent, Detrended Fluctuation Analysis, Minimum Embedding Dimension). When compared to rest, variability at the heaviest exercise intensity was significantly lower (RR: 0.94 +/- 0.22 vs. 0.34 +/- 0.01 ms; SDRR: 0.11 +/- 0.04 vs. 0.01 +/- 0.00 ms) due to a decrease in both LF (2101 +/- 1450 vs. 0.14 +/- 0.09 ms (2) . Hz (-1)) and HF spectral energy (1148 +/- 1126 vs. 7.88 +/- 9.24 ms (2) . Hz (-1)). Non-linear analyses showed that heart rate variability remained chaotic whatever the exercise intensity (the largest Lyapunov exponent was positive at 90 % of the maximal oxygen uptake), with a fractal organisation that tended towards white noise (DFA value close to 0.5) during heavy exercise. During recovery, temporal and spectral variables came back to their rest values within about 30 minutes following an exponential pattern. Non-linear analyses revealed that heartbeat dynamics were disorganised at the beginning of recovery, and involved more regulating systems than at rest, even after 50 minutes of recovery. We concluded that, during heavy exercise, heart rate variability was mainly influenced by other factors than autonomous nervous system, and suggest that mechanical or neurological couplings between the cardiac, locomotor and respiratory systems could play an important part in the observed changes.

Sickle Cell Trait in French West Indian Elite Sprint Athletes

The aim of this study was to establish the percentage of sickle cell trait (SCT) carriers among French West Indian sprinters selected for the French National Team in 2000. The investigation determined the number of SCT carriers and the number of national records they had established. Sixteen athletes were indexed (6 males and 10 females). The athletes were within the ranges of 20-33 years, 161-186 cm and 60-80 kg. The results showed the presence of SCT carriers in this population among whom three were SCT carriers (2 males and 1 female) (18.75%). Moreover, there is a significantly higher percentage of titles and records held by the SCT carriers (38.6% and 50%, respectively). In conclusion, this study shows that sickle cell trait carriers are able to perform sprint exercises at the highest levels, and it further indicates that brief and explosive exercise involving mainly the alactic anaerobic metabolism may be enhanced by HbS.

High versus low training frequency in cardiac rehabilitation using a systems model of training

No study has reported the long term effects of cardiac rehabilitation, concerning the duration of beneficial effects of training program. The present study analyzed the influence of training session frequency on long-term beneficial effects in patients with coronary artery disease (CAD) undergoing phase 2 cardiac rehabilitation. Four patients with CAD completed 20 training sessions. Two patients were assigned to low training frequency (LTF) and two to high training frequency (HTF): three and five sessions per week(-1), respectively. The method was based on the systems model of training and required training quantification and the assessment of real exercise tolerance. Convolution of training quantity with real exercise tolerance provided the model exercise tolerance for every patient. The model parameters, the magnitude factor (k), and the time constant of decay (tau), were fitted from real and model exercise tolerances by the least squares method. LTF and HTF resulted in similar increases in exercise tolerance (12-14%). A model with one-component (fitness) allowed fitting exercise tolerance in all patients with r (2) = 0.77, 0.79, 0.84, and 0.91, respectively (p < 0.05). The addition of a second component did not improve the fit in any patient (p > 0.05). The k value was about twice as high with LTF (0.13 and 0.16 AU) than with HTF (0.05 AU for the two patients), whereas the tau value was about twice as low with LTF (37 and 41 days) than with HTF (72 and 89 days). The long term beneficial effects estimated by 4tau, were twice as long with HTF (288 and 356 days) than with LTF (148 and 164 days). We concluded that exercise tolerance was similarly increased with HTF and LTF but HTF training induced beneficial effects which were sustained twice as long.

Effect of sleep deprivation on shuttle run score in middle-aged amateur athletes. Influence of initial score

AIM

The aim of the present study was to investigate the effect of sleep deprivation on shuttle run score (corresponding to an estimated VO2 peak) in middle-aged amateur athletes.

METHODS

Twenty-two athletes, training 9.2 hours a week (+/-4), performed a Leger and Gadoury shuttle test daily in a 4-day series that included a pre-test in day 0, 28 hours without sleep before test 1 (and 10 another hours after the test and before bedtime for a sleep deprivation of 38 hours), and then 10 hours of sleep before each of days 2 and 3.

RESULTS

Shuttle run score showed no significant difference over the 4 days; however, the change in shuttle run score on day 2 was significantly correlated with the initial score.

CONCLUSIONS

This result suggests that effect of sleep deprivation on shuttle run score is dependent on initial score and may encourage high level aerobic athletes to avoid sleep deprivation 2 days before a competition.

Does systemic inflammation trigger local exercise-induced oxidative stress in COPD?

Inflammatory abnormalities may be involved in the inadequate basal oxidant/antioxidant balance and local exercise-induced oxidative stress in chronic obstructive pulmonary disease (COPD) patients. The time course of oxidative stress and inflammation was investigated in 10 COPD patients and seven healthy subjects before and after local dynamic quadriceps endurance exercise at 40% of maximal strength. Venous samples were collected before, immediately after and up to 48 h after exercise. At rest, levels of an oxidant released by stimulated phagocytes, the superoxide anion, were significantly higher in patients, as were plasma levels of C-reactive protein, tumour necrosis factor-alpha and interleukin-6, inflammatory markers. An inverse relationship was found between baseline C-reactive protein levels and endurance time in patients. Six hours after exercise, superoxide anion release and levels of protein oxidation products, an index of oxidative stress, increased similarly in both groups, whereas thiobarbituric acid reactive substance levels, another index of oxidative stress, increased significantly only in patients. Plasma nonenzymatic antioxidant and inflammatory cytokine levels were unchanged by the exercise protocol. The increased baseline systemic inflammation in chronic obstructive pulmonary disease patients could be related to disturbed oxidant/antioxidant balance, and, together, these may have triggered the exercise-induced oxidative stress. The absence, however, of local exercise-induced systemic inflammation suggests that additional mechanisms explain local exercise-induced oxidative stress.

Effects of successive running and cycling on the release of atrial natriuretic factor in highly trained triathletes

AIM

To evaluate the influence of successive running and cycling on both exercise-induced arterial hypoxemia (EIAH) and atrial natriuretic factor (ANF) release, 5 triathletes performed 2 separate exercise trials.

METHODS

One trial consisted of a 20-min+20-min successive cycle-run exercise (C(1)-R(2)) and the other consisted of a 20-min+20-min successive run-cycle exercise (R(1)-C(2)). Arterial oxygenation (PaO(2)) and ANF were determined at pre-exercise, at the end of each 20-min segment of exercise and after 10 min of recovery.

RESULTS

EIAH was noted during C(1)-R(2) and R(1)-C(2) trials. A higher EIAH was observed during running compared with cycling performed in the 1(st) position (R(1) vs C(1)) in the succession. In contrast, no difference was observed between successive running and successive cycling (R(2) vs C(2)), (-10.6+/-7.0 vs -15.6+/-4.0 mmHg for C(1)-R(2) and -20.9+/-6.0 vs -16.2+/-2.4 mmHg for R(1)-C(2)). ANF showed no difference between cycling and running performed in first position, whereas a significantly lower ANF was observed during successive cycling compared with successive running (C(2) vs R(2)) (19.9+/-3.72 vs 36.2+/-6.4 pmol.L(-1)). During recovery, neither PaO(2) nor ANF plasma returned to baseline level after either trial.

CONCLUSION

This study provides new information on some of the physiological modifications that occur during multi-sports. Specifically, the impact of the modality of the successive exercise on ANF release and body fluid regulation was observed. Cycling as the successive exercise seems to cause lower ANF release than does running.

Pulmonary function during cycling and running in triathletes

AIM

Running performance has become key to the triathlete's overall performance. We still know relatively little about the factors that define the ability to perform a good run after cycling, however, and the perception of discomfort during the first minutes of this post-cycling running has yet to be satisfactorily explained. Pulmonary volumes (i.e., residual volume, RV, and functional residual capacity, FRC) have been demonstrated to be impaired after a cycle-run succession in triathletes but not after a run-run succession that is matched in terms of intensity and duration. Cycling in itself and/or the succession of two different exercises (i.e., cycling and running) may explain this phenomenon, but the exact mechanism has not yet been determined.

METHODS

Thirteen young male triathletes participated in three different exercise trials: 30 min of cycling followed by 20 min of running (C-R), 30 min of control cycling (C) and 20 min of control running (R). Pulmonary volumes and flows were measured 10 min before and 10 min after each trial. During all trials, ventilatory data were collected every minute using an automated breath-by-breath system.

RESULTS

The results showed that 1) C induced significant increases in RV, FRC and RV/TLC (2.31+/-0.18 vs 2.01+/-0.17 L, 4.35+/-0.24 vs 4.01+/-0.25 L, and 27.21+/-1.62 vs 23.98+/-1.55, respectively, after versus before C) and 2) there were no significant pulmonary volume or flow changes after C-R or R.

CONCLUSION

We concluded that 1) cycling exercise in itself seems to increase the post-exercise pulmonary volume changes which could lead to respiratory muscle alterations and 2) one likely explanation for this finding appears to be the crouched position of cycling.

The effects of prior cycling and a successive run on respiratory muscle performance in triathletes

The aim of the present study was to compare the effects of prior cycling and a successive run on respiratory muscle performance during a cycle-run succession as performed in the triathlon. We hypothesized that despite the moderate intensity of exercise and the absence of exhaustion, the crouched cycling position would induce a decrease in respiratory muscle performance that would be reversed by the successive vertical run position. Ten male triathletes (22.6 +/- 1.1 yr) performed a four-trial protocol: (1) an incremental cycle test to assess maximal oxygen uptake (VO2max), (2) 20 min of cycling (C), (3) 20 min of running (R), and (4) 20 min of cycling followed by 20 min of running (C-R). Trials 2, 3 and 4 were performed at the same metabolic intensity, i. e., 75 % of VO2max. Respiratory muscle force was assessed by measuring maximal expiratory (P(Emax)) and inspiratory (P(Imax)) pressures from the functional residual capacity (FRC) before and 10 min after C, R, and C-R. Respiratory muscle endurance was assessed one day before and 30 min after C, R, and C-R, by measuring the time limit (T(lim)), which corresponds to the length of time a respiratory load can be sustained before the process of fatigue develops sufficiently to cause task failure. The results showed a similar significant decrease in P(Imax) (132.4 +/- 4.9 versus 125.7 +/- 5.6 cm H2O, p < 0.05) and T(lim) (5.22 +/- 0.28 versus 3.68 +/- 0.32 min, p < 0.05) post-C and post-C-R (133.7 +/- 4.0 versus 126.9 +/- 5.2 cm H2O, and 5.29 +/- 0.18 versus 3.49 +/- 0.41 min, respectively, p < 0.05) compared with the pre-trial values. In contrast, P(Imax) and T(lim) were not significantly decreased post-R (131.8 +/- 6.1 cm H2O versus 129.6 +/- 6.4 cm H2O, and 4.90 +/- 0.69 versus 4.40 +/- 0.56 min, respectively, p > 0.05). We concluded that moderate intensity exercise not performed to exhaustion induced a decrease in respiratory muscle performance. Moreover, the respiratory muscle fatigue induced by prior cycling was maintained, and neither reversed nor worsened, by the successive run.

Prediction of VO(2peak) in wheelchair-dependent athletes from the adapted Léger and Boucher test

PURPOSE

:The purpose of this study was to provide a predictive peak oxygen uptake ([V]O(2) peak) equation in wheelchair-dependent athletes using the Adapted Léger and Boucher test. SUBJECTS AND PROTOCOL: :Fifty-six wheelchair-dependent athletes, 47 males and nine females (30.3+/-4 years), underwent a clinical examination to assess their anthropometric characteristics: height, mass, body mass index (BMI), lean body mass, arm length, and muscular arm volume. They performed a deceleration field test to assess the subject-wheelchair resistance defined as a mechanical variable, and they then performed the Adapted Léger and Boucher test to assess physiological data at maximal exercise ([V]O(2) peak, heart rate max) concomitantly with biomechanical (number of pushes) and performance variables (maximal aerobic velocity Va(max) and maximal distance). The [V]O(2) peak was measured directly using a portable telemetric oxygen analyzer. Subjects were then randomly assigned to an experimental group (n=49) to determine the predictive equation, and a validation group (n=7) to check the external validity of the equation.

RESULTS

A stepwise multiple regression with [V]O(2) peak (l min(-1)) as the dependent variable led to the following equation: [V]O(2) peak=0.22 Va(max) - 0.63 log(age)+0.05 BMI 0.25 level+0.52, with r(2)=0.81 and SEE=0.01. Paraplegic subjects with high and low lesion level spinal injuries were attributed the coefficient of 1 and 0, respectively. The external validity of the equation was positive since the predicted [V]O(2) peak values did not significantly differ from directly measured [V]O(2) peak (P>0.05).

CONCLUSION

We concluded that [V]O(2) peak in wheelchair-dependent athletes was predictable using the equation of the present study and the described incremental test.

The effect of cycling followed by running on respiratory muscle performance in elite and competition triathletes

This study investigated the possibility of there being differences in respiratory muscle strength and endurance in elite and competition triathletes who have similar maximal oxygen uptakes (VO(2max)) and ventilatory thresholds (Th(vent)). Five internationally-ranked elite, [mean (SD) age 23.8 (1.4) years] and six nationally- and regionally-ranked competition [age 21.1 (1.1) years] male triathletes performed two successive trials: first an incremental cycle test to assess VO(2max) and Th(vent) and second 20 min of cycling followed by 20 min of running (C-R) at intensities higher than 85% VO(2max). Cardioventilatory data were collected every minute during the two trials, using an automated breath-by-breath system. Maximal expiratory and inspiratory (P(Imax)) strength were assessed before and 10 min after C-R from the functional residual capacity. Respiratory muscle endurance was assessed 1 day before and 30 min after C-R by measuring the time limit (t(lim)). The results showed firstly that during C-R, the competition triathletes had significantly (P < 0.05) higher minute ventilation [mean (SEM) 107.4 (3.1) compared to 99.8 (3.7) l x min(-1)], breathing frequency [44.4 (2.0) compared to 40.2 (3.4) x min(-1)] and heart rate [166 (3) compared to 159 (4) beats x min(-1)] and secondly that after C-R, they had significantly lower P(Imax) [127.1 (4.2) compared to 130.7 (3.0) cmH(2)O] and t(lim) [2:35 (0:29) compared to 4:12 (0:20) min] than the elite triathletes. We conclude that, despite similar VO(2max) and Th(vent), the competition triathletes showed less extensive adaptive mechanisms, including those in the respiratory muscles, than did the elite triathletes. This led to higher ventilation, which appeared to be the cause of the faster development of fatigue in the inspiratory muscles in this group.

Alactic anaerobic performance in subjects with sickle cell trait and hemoglobin AA

The aim of the present study was to assess the performance of subjects with sickle cell trait (SCT) during brief and explosive exercise involving mainly anaerobic metabolism. One hundred and ninety-six black subjects underwent SCT screening, which revealed the presence of 16 subjects with SCT and 180 subjects with normal hemoglobin (HbAA). All subjects performed four tests: 1) a 100-m sprint, 2) a long-jump, 3) a Leger-Boucher shuttle test and 4) a jump-and-reach test. A control group (n = 18) selected from the 180 subjects with HbAA was matched according to the sex, age, weight and height of the SCT subjects (SCTs). The performances of the SCTs (n = 16) were compared with those of the control group. The performances were similar between the SCTs and control group for the sprint test, long-jump and the Leger-Boucher shuttle test. There was, however, a significant difference for the jump-and-reach test between the two groups: the SCTs (i. e., males plus females, and males and females considered separately) reached a significantly greater height (p < 0.05) than the matched subjects of the control group (63.7 +/- 3.6 vs. 58.6 +/- 3.1 cm, 72.3 +/- 3.9 vs. 67.1 +/- 2.4 cm and 52.7 +/- 3.2 vs. 45.3 +/- 2.0 cm for SCTs versus non-SCTs, for the group, the males and the females, respectively). The results of the present study suggest that the performance of brief and explosive exercise may be enhanced by HbS.

Cardiorespiratory responses and blood lactate during an experimental run-cycle transition in duathletes

The aim of this study was to determine the effects of a prior run on the cardiorespiratory responses measured during a subsequent cycle segment. Twelve duathletes underwent three successive laboratory trials at an interval of one week: 1) an incremental cycle test, 2) 20 min of running followed by 20 min of cycling (RC), and 3) 20 min of control cycling (C) at the same intensity as the cycling segment of RC. Ventilatory data were collected every minute using a breath-by-breath automated system. Blood samples were collected to measure venous blood lactate concentration, [La], at rest, after the running and cycling segments of RC and after C. The results showed that the C segment of RC had significantly higher VE, VE/VO2, f and HR than C alone and significantly lower VT (p < 0.05) than C alone. Moreover, steady state during C of RC was reached at the 2nd min for VO2, VE, VCO2, VE/VO2, VE/VCO2, and VdT; at the 4th min for R and HR, and at the 5th min for f. The C of RC induced a significant increase in [La] in comparison with C alone. We concluded that the first minute of cycling after running during an RC trial induced specific metabolic and cardiorespiratory responses.

Specific pulmonary responses during the cycle-run succession in triathletes

The aim of the present study was to investigate the relationship between alterations in pulmonary function (i.e., diffusing capacity for carbon monoxide and pulmonary volumes) and the ventilatory response elicited during the cycle-run succession in triathletes. Ten well-trained triathletes performed three exercises: 1) 30 min cycling plus 20 min of running, termed the cycle-run succession; 2) 30 min cycling; and 3) 20 min running. Before and 10 min after each trial, the triathletes underwent pulmonary function testing, including spirometry and diffusing capacity for carbon monoxide. During all trials, ventilatory data were collected every minute using an automated breath-by-breath system. The ventilatory response was significantly higher in the run subsequent to cycling as compared with the run performed independently (P<0.001). There was no change in pulmonary volumes before and after exercises; however, the diffusing capacity for carbon monoxide and the transfer coefficient were similarly decreased (P<0.05) after cycling and the cycle-run succession, but not decreased after running. The increase in minute ventilation in the run segment of the cycle-run succession versus in running alone was significantly correlated with the decrease in diffusing capacity for carbon monoxide measured after versus before the cycle-run succession (P<0.01). This same increase in ventilation was also correlated with the decrease in diffusing capacity measured after the cycle-run succession versus after cycling alone (P<0.03). These results suggest the possibility that the DLCO decrease contributes in part to the ventilatory increase noted in the run after cycling during the cycle-run succession of the triathlon.

The effect of exercise modality on respiratory muscle performance in triathletes

PURPOSE

The aim of this study was to examine the effects of the cycle-run and run-cycle successions of the triathlon and duathlon, respectively, on respiratory muscle strength and endurance.

METHODS

Respiratory muscle strength was assessed by measuring maximal inspiratory (P(Imax)) and expiratory (P(Emax)) pressures. Respiratory muscle endurance was assessed by measuring the time limit (T(lim)). Twelve triathletes participated in a three-trial protocol. The first trial consisted of an incremental cycle test to assess the maximal oxygen uptake (.VO(2max)) of triathletes. Trial 2 consisted of 20 min of cycling followed by 20 min of running (C-R), and trial 3 consisted of 20 min of running followed by 20 min of cycling (R-C). Trials 2 and 3 were performed at the same metabolic intensity (%.VO(2max)). P(Imax) and P(Emax) were measured before and 10 min after C-R and R-C, and 1 min after the post-C-R and post-R-C T(lim) measurements (P(Imax) 1'). T(lim) was measured 1 d before and 30 min after C-R and R-C.

RESULTS

The results showed a significant decrease in P(Imax) after C-R (126.7 +/- 4.3 cmH(2)O, P < 0.05) and R-C (123.7 +/- 4.9 cmH(2)O, P < 0.05) compared with the baseline values (130 +/- 3.8 and 129.6 +/- 4.3 cmH(2)O, respectively). P(Imax) 1' showed a significantly greater decrease after R-C versus C-R (111.2 +/- 5.5 cmH(2)O vs 121.2 +/- 3.9 cmH(2O), respectively, P < 0.001). Tlim after C-R (3.3 +/- 0.3 min) and R-C (2.1 +/- 0.3 min) decreased significantly compared with baseline values (4.19 +/- 0.3 min and 4.02 +/- 0.3 min, respectively). However, the Tlim decrease after R-C was significantly greater than after C-R (P < 0.001).

CONCLUSION

We concluded that respiratory muscle strength and endurance were less decreased after the cycle-run succession and that cycling induced a greater decrease in respiratory muscle endurance than running.

Pulmonary responses during the cycle-run succession in elite and competitive triathletes

OBJECTIVES

The purpose of this study was to determine the effect of performance level on the pulmonary responses in triathletes during the cycle-run succession.

METHODS

Eight regionally and nationally ranked (Competitive) and six internationally ranked (Elite) male triathletes underwent 30 min of cycling followed by 20 min of running (C-R) and 30 min of control cycling (C). Before and 10 min after each trial, the triathletes underwent lung function testing. Ventilatory data were collected every minute using an automated breath-by-breath system.

RESULTS

The results showed that (a) cycling induced a significant increase in residual volume and functional residual capacity in the Elite group (P <.05); (b) although cycling induced a significant decrease in DLCO in both groups, this decrease persisted at the end of the cycle-run exercise in the Competitive group only (P <.05); and (c) the rise in breathing frequency was significantly greater in the Competitive triathletes during the first 8 min of the subsequent run (P <.04).

CONCLUSIONS

We conclude that the internationally ranked--or elite-performance--triathletes may have developed specific responses to the cycle-run succession.

DLCO response to experimental cycle-run succession in triathletes

BACKGROUND

We still know relatively little about the factors that define the ability to perform a good run after cycling in triathlon, however, and the perception of discomfort during the first minutes of this post-cycling running has yet to be satisfactorily explained. The pulmonary diffusion capacity for carbon monoxide (DLCO) has been demonstrated to be impaired after the cycle-run succession. Numerous causes have been suggested to explain this phenomenon, but the exact mechanism has not yet been determined.

METHODS

Thirteen young male triathletes participated in four different exercise trials: 30 min of cycling followed by 20 min of running (C-R, 1 min rest between C and R), 30 min of running followed by 20 min of running (R-R, 1 min rest between R and R), 30 min of cycling (C), and 30 min of running (R). DLCO and alveolar volume were simultaneously measured during 9 sec of breath-holding before and 10 min after exercise. The transfer coefficient (KCO=DLCO/VA) was then calculated. During all trials, ventilatory data were collected every minute using an automated breath-by-breath system.

RESULTS

The results showed that 1) C-R and C induced significant and identical decreases in DLCO and KCO in post-trial compared with pre-trial measurement (40.41+/-2.24 vs 43.49+/-2.36 ml x min(-1) x mm Hg(-1), p<0.01, and 39.37+/-2.16 vs 42.99+/-2.38 ml x min(-1) x mm Hg(-1), p<0.02, for C-R and C, respectively) and 2) there were no DLCO decreases in post-trial compared with pre-trial measurement in R-R and R.

CONCLUSIONS

We concluded that cycling exercise in itself seems to increase the immediate post-exercise DLCO impairment.

The effect of multi-cycle-run blocks on pulmonary function in triathletes

BACKGROUND

This study was designed to determined the pulmonary responses elicited by multi-cycle-run exercise in triathletes and to compare them to those elicited during a simple cycle-run succession.

METHODS

Twelve male triathletes underwent three successive laboratory trials: 1) an incremental cycle test, 2) 30 min of cycling followed by 20 min of running (C-R), and 3) five repeated bouts of 6 min of cycling and 4 min of running (X-CR). Before and 10 minutes after the third and fourth trials, the triathletes underwent lung function testing, especially spirometry and diffusing capacity testing for carbon monoxide (DL(CO)). During all trials, ventilatory data were collected every minute using an automated breath-by-breath system.

RESULTS

The results showed that: 1) the cardiorespiratory responses observed during running were greater in the X-CR trial for VE/VCO2 and HR, 2) DL(CO) and DL(CO)/VA were significantly reduced after both trials, and 3) there were no significant changes in pulmonary volumes.

CONCLUSIONS

We concluded that 1) the multi-block trial elicited greater cardioventilatory responses than simple the cycle-run succession and 2) multi-block seems a good method to stimulate the specific adaptations required for the cycle-run succession, and particularly for the cycle-run transition. In any case, the efficacy of the multi-block model needs to be more thoroughly evaluated over the course of a longer-term training programme.

Factor analysis of quality of life, dyspnea, and physiologic variables in patients with chronic obstructive pulmonary disease before and after rehabilitation

OBJECTIVE

To identify the relationships between quality of life (QOL) and the clinical state using factor analysis pre- and postrehabilitation. Patients with chronic obstructive pulmonary disease (COPD) suffer from a significant physiologic impairment associated with an altered QOL. Comprehensive rehabilitative programs, including exercise training, have beneficial effects on exercise tolerance and QOL for these patients.

DESIGN

Factor analysis (n = 6) was conducted using the data of 32 patients with COPD. Patients had been evaluated for QOL using the Nottingham Health Profile (NHP), spirometric values, dyspnea, and the variables assessed by an incremental exercise test at three levels of activity. All measurements were obtained pre- and postrehabilitation.

RESULTS

Factor analysis showed that the following two factors characterize the pathophysiologic condition of patients with COPD: (1) the specific cardiorespiratory responses to incremental exercise test and the spirometric values; and (2) the QOL results. The factor analysis results differed with the testing time (pre, post) and the level of activity.

CONCLUSIONS

QOL, as evaluated by a generic questionnaire and the clinical state of patients with COPD, was independent; this independence characterized the pathophysiologic condition of our patients. Our results reinforce the usefulness of different types of evaluation, especially pre- and postrehabilitation, because they reflect independent benefits used to understand the success and follow-up of rehabilitative programs.

Catecholamine, blood lactate and ventilatory responses to multi-cycle-run blocks

PURPOSE AND METHODS

This study was designed to determine whether the physiological responses elicited during the run part of repeated bouts of cycle-run exercise are similar to those required during the run segment of a cycle-run succession. Thirteen male triathletes underwent four successive laboratory trials: 1) an incremental treadmill test, 2) an incremental cycle test, 3) 30 min of cycling followed by 20 min of running (C-R), and 4) five repeated bouts of 6 min of cycling and 4 min of running (X-CR). During the C-R and X-CR trials, venous blood samples were obtained to measure lactate, epinephrine and norepinephrine concentrations. During all trials, ventilatory data were collected every min using an automated breath-by-breath system.

RESULTS

The results showed that 1) the cardiorespiratory responses observed during running were similar in the X-CR and C-R trials, 2) the lactate concentration was similar in both trials, 3) the epinephrine concentration was greater (277.9 +/- 11.9 vs 169.8 +/- 86.7 pg x mL(-1), P < 0.025) in X-CR than in C-R, and 4) the norepinephrine concentration was similar in both trials, except at the first cycle-run succession (T1) of X-CR.

CONCLUSION

We concluded that 1) multi-block training is a good method to stimulate the specific adaptations required for the cycle-run succession, and particularly for the cycle-run transition, and 2) multi-block training seems to induce a greater catecholaminergic response, which may be due to a combination of an inherent effect of this type of training and the triathletes' relative lack of experience with it. In any case, the efficacy of the multi-block model needs to be more thoroughly evaluated over the course of a longer-term training program.

Performance level and cardiopulmonary responses during a cycle-run trial

To determine the effect of triathlete performance level on the cardiorespiratory responses elicited by the cycle-run succession, eight regionally and nationally-ranked (Competitive) and five internationally-ranked (Elite) male triathletes underwent four successive laboratory trials: 1) an incremental treadmill test, 2) an incremental cycle test, 3) 30 min of cycling followed by 20 min of running (C-R), and 4) a 20-min control run (R) at the same speed as the run in C-R. Before and 10 min after the third and fourth trials the triathletes underwent lung function testing: spirometry and diffusing capacity testing for carbon monoxide (DL(CO)). During the C-R trial blood samples were drawn to measure venous lactate concentration. During all trials ventilatory data were collected every minute using an automated breath-by-breath system. The results showed that 1) the oxygen uptake (VO2) of post-cycling running versus running alone was similar for both groups; 2) the ventilatory responses (VE, VE/VO2, VE/VC02 and f) of C-R running versus R were significantly higher (P < 0.005) for the Competitive group; and 3) a significant decrease (P< 0.05) in DL(CO) was also noted after the C-R trial in the Competitive group but not in the Elite group. We concluded that 1) the ventilatory responses during a run subsequent to cycling may be related to the triathlete performance level, and 2) the C-R trial induced specific alterations in pulmonary function that may be associated with respiratory muscle alteration and exercise-induced hypoxemia in the Competitive triathletes.

Ventilatory threshold and maximal oxygen uptake in present triathletes

The aim of this study was to determine the physiological profile of young triathletes who began triathlon competition as their first sport. Twenty-nine male competitive triathletes (23 regionally and nationally ranked triathletes and 6 elite, internationally ranked triathletes) performed two tests, one on a cycle ergometer (CE VO2max) and one on a treadmill (TM VO2max). Results showed (a) no difference between CE VO2max and TM VO2max in the triathletes (69.1 +/- 7.2 vs. 70.2 +/- 6.2 mL x kg(-1) x min(-1), respectively), (b) values of CE VO2max and TM VO2max in elite triathletes (75.9 +/- 5.2 and 78.5 +/- 3.6 mL x kg(-1) x min(-1), respectively) that were comparable to those reported in elite single-sport athletes in these specialities, and (c) although the ventilatory threshold (Th(vent)) was similar in CE and TM, TM Th(vent) was consistently lower for triathletes than TM Th(vent) usually reported for runners.

Cardiorespiratory and metabolic responses to exercise in HbSC sickle cell patients

PURPOSE

Relative to healthy control individuals with normal hemoglobin (Hb), patients carrying the double heterozygous form of sickle cell disease (HbSC) display an impaired oxygen transport capacity. The present study was undertaken to determine the influence of the decreased oxygen availability associated with the presence of HbSC on the cardiorespiratory and metabolic responses to endurance exercise.

METHODS

Eleven black men affected by the double heterozygous form of the sickle cell disease (HbSC group) and seven healthy subjects with normal Hb (HbAA group) of the same ethnic origin submitted successively to an incremental exercise test to exhaustion on a cycle ergometer for the determination of their maximal tolerated power and to a 20-min endurance exercise.

RESULTS

The HbSC had a significantly lower exercise tolerance than the HbAA. During the endurance exercise, they exhibited furthermore significantly lower VO2, VCO2, and minute ventilation V(E) than the HbAA. Despite the fact that the HbSC exercised at a significantly lower mean absolute work rate than the HbAA, except for the ventilatory equivalent for CO2 (V(E)/VCO2), which was higher (P < 0.001) in the HbSC group, the other parameters recorded during the 20-min endurance exercise (heart rate, arterial PaO2, PaCO2, pH, lactate, and VE/VO2, the ventilatory equivalent for O2) and during the subsequent recovery (blood lactate) were similar for both groups.

CONCLUSION

The study underscores the importance of considering relative work rate as well as absolute work rate to arrive at a correct interpretation of exercise and recovery data. The results give evidence that the modifications of homeostasis brought into play by exercise were shifted toward distinctly lower absolute work rates in HbSC patients.

Ventilatory responses during experimental cycle-run transition in triathletes

PURPOSE AND METHODS

To determine the effects of cycling on a subsequent triathlon run, nine male triathletes underwent four successive laboratory trials: 1) an incremental treadmill test, 2) an incremental cycle test, 3) 30 min of cycling followed by 5 km of running (C-R), and 4) 30 min of running followed by 5 km of running (R-R). Before and 10 min after the third and fourth trials, the triathletes underwent pulmonary function testing including spirometry and diffusing capacity testing for carbon monoxide (DL(CO)). During the C-R and R-R trials, arterialized blood samples were obtained to measure arterial oxygen pressure (PaO2). During all trials, ventilatory data were collected every minute using an automated breath-by-breath system.

RESULTS

The results showed that 1) the oxygen uptake (VO2) observed during subsequent running was similar for the C-R and R-R trials; 2) the ventilatory response (VE) during the first 8 min of subsequent running was significantly greater in the C-R than in R-R trial (P < 0.05); 3) only the C-R trial induced a significant increase (P < 0.05) in residual volume (RV), functional residual capacity (FRC), and the ratio of residual volume to total lung capacity (RV/TLC); and 4) although a significant decrease (P < 0.05) in DL(CO) was noted after C-R, no difference between the two exercise trials was found for the maximal drop in PaO2.

CONCLUSIONS

We concluded that 1) the C-R trial induced specific alterations in pulmonary function that may be associated with respiratory muscle fatigue and/or exercise-induced hypoxemia, and 2) the greater VE observed during the first minute of running after cycling was due to the specificity of cycling. This reinforces the necessity for triathletes to practice multi-trial training to stimulate the physiological responses experienced during the swim-cycle and the cycle-run transitions.

Quality of life and exercise tolerance in chronic obstructive pulmonary disease: effects of a short and intensive inpatient rehabilitation program

The quality of life and the exercise endurance of patients with chronic obstructive pulmonary disease are impaired. The aim of our study was to determine the impact of a 3-wk intensive inpatient rehabilitation program on the quality of life of patients with chronic obstructive pulmonary disease and to examine the correlation between quality-of-life measures and physiologic measures throughout rehabilitation. Thirty-two patients with chronic obstructive pulmonary disease (20 men, 12 women) were evaluated by spirometry and maximal exercise testing for exercise endurance and by the French version of the Nottingham Health Profile for quality of life. Rehabilitation components were individualized exercise at ventilatory threshold (4 hr/day), health education, and physical therapy and relaxation for 3 wk. Our results showed an improvement in the quality of life (especially in physical mobility, energy, and social isolation) and exercise endurance (increase of 14% of maximal power and symptom-limited oxygen uptake). In contrast, no significant correlations were found between the quality of life and physiologic parameters (gas exchange, cardiovascular and lung function parameters) throughout rehabilitation. Changes in the quality of life seem to be independent of the physiologic results during the course of a short and intensive inpatient rehabilitation program. Quality of life should, therefore, be more systematically evaluated to determine the psychosocial benefits, which, although subjective, are important for encouraging patients' compliance with rehabilitation programs.

Metabolic and cardioventilatory responses during a graded exercise test before and 24 h after a triathlon

Previous studies have reported respiratory, cardiac and muscle changes at rest in triathletes 24 h after completion of the event. To examine the effects of these changes on metabolic and cardioventilatory variables during exercise, eight male triathletes of mean age 21.1 (SD 2.5) years (range 17-26 years) performed an incremental cycle exercise test (IET) before (pre) and the day after (post) an official classic triathlon (1.5-km swimming, 40-km cycling and 10-km running). The IET was performed using an electromagnetic cycle ergometer. Ventilatory data were collected every minute using a breath-by-breath automated system and included minute ventilation (V(E)), oxygen uptake (VO2), carbon dioxide production (VCO2), respiratory exchange ratio, ventilatory equivalent for oxygen (V(E)/VO2) and for carbon dioxide (V(E)/VCO2), breathing frequency and tidal volume. Heart rate (HR) was monitored using an electrocardiogram. The oxygen pulse was calculated as VO2/HR. Arterialized blood was collected every 2 min throughout IET and the recovery period, and lactate concentration was measured using an enzymatic method. Maximal oxygen uptake (VO2max) was determined using conventional criteria. Ventilatory threshold (VT) was determined using the V-slope method formulated earlier. Cardioventilatory variables were studied during the test, at the point when the subject felt exhausted and during recovery. Results indicated no significant differences (P > 0.05) in VO2max [62.6 (SD 5.9) vs 64.6 (SD 4.8) ml x kg(-1) x min(-1)], VT [2368 (SD 258) vs 2477 (SD 352) ml x min(-1)] and time courses of VO2 between the pre- versus post-triathlon sessions. In contrast, the time courses of HR and blood lactate concentration reached significantly higher values (P < 0.05) in the pre-triathlon session. We concluded that these triathletes when tested 24 h after a classic triathlon displayed their pre-event aerobic exercise capacity, bud did not recover pretriathlon time courses in HR or blood lactate concentration.

Blood lactate concentrations during incremental exercise in subjects with sickle cell trait

The aim of the present study was to assess blood lactate concentrations ([LA], mmol x L(-1)) and oxygen uptake (VO2, L x min(-1), mL x kg(-1) x min(-1)) during incremental exercise in subjects with sickle cell trait (SCT) only, i.e., sedentary subjects with SCT without anemia and/or associated alpha thalassemia. Anemia was ruled out using hemoglobin (Hb) level, and alphathalassemia was ruled out using hemoglobin S (HbS) percentage and concomitant Hb level and mean corpuscular volume (MCV). Comparison was made with control subjects with normal Hb, matched for physical fitness, anthropometric data, and hematological parameters. All subjects underwent an incremental exercise test (IET) using an electromagnetic cycle ergometer. Ventilatory data, i.e., minute ventilation (VE, L x min(-1)), oxygen uptake (VO2, mL x min(-1), mL x Kg(-1) x min(-1)) carbon dioxide production (VO2, mL x min(-1)), ventilatory equivalent for O2(VE x VO2(-1))and for CO2 (VE x VO2(-1)), and respiratory exchange ratio (RER, VO2 x VO2(-1)), were collected every minute during IET and the recovery period using a breath-by-breath automated system. Heart rate (HR, beats x min(-1)) was measured every minute using an EKG. Blood sampling was done every minute during IET and the first 5 min of the recovery period, and then every 5 min until the 20th minute of recovery. [LA] were determined by an enzymatic method with a spectrophotometer. Comparisons of all mean cardioventilatory variables showed no significant differences in subjects with SCT versus controls during IET and recovery. In contrast, analysis of variance revealed significantly lower time courses of [LA] during IET (P < 0.05) and recovery (P < 0.05), whereas time courses of VO2 were similar (P > 0.05). We conclude that the lower [LA] exhibited by subjects with SCT during incremental exercise and the subsequent recovery was not associated with concomitant oxygen uptake impairment.

Sickle cell trait in Ivory Coast athletic throw and jump champions, 1956-1995

In order to assess the performance of subjects with sickle cell trait (SCT) during brief and explosive exercise involving mainly alactic anaerobic metabolism, the percentage of athletes with SCT was determined in Ivory Coast track and field throw and jump champions, both men and women, for the period 1956-1995. Thirty-four (27.8%) sickle cell trait carriers (SCTC) were identified among the 122 national champions that we were able to contact. These 34 SCTC had won 78 national titles (24.5%) and established 37 national records (43.5%), distributed among the throw and jump events. These percentages were significantly higher than the prevalence of SCT in the general Ivory Coast population (12.0%). The women's high jump and men's shot put events had the highest percentages of SCTC record holders (90.9% and 87.5%, respectively). Moreover, the two top national record holders and title winners, one man and one woman, were SCTC athletes, and their hemoglobin S percentage (HbS: 39.1% and 39.4%, respectively) and mean corpuscular volume (MCV) excluded an associated alpha-thalassemia. We conclude that the significantly higher percentage of SCTCs among Ivory Coast track and field champions, as compared to the percentage in the general population suggests that SCT may be a determinant factor for success in brief and explosive track and field events involving mainly alactic anaerobic metabolism.

The influence of prior cycling on biomechanical and cardiorespiratory response profiles during running in triathletes

The aim of the present study was to determine the effects of 40 km of cycling on the biomechanical and cardiorespiratory responses measured during the running segment of a classic triathlon, with particular emphasis on the time course of these responses. Seven male triathletes underwent four successive laboratory trials: (1) 40 km of cycling followed by a 10-km triathlon run (TR), (2) a 10-km control run (CR) at the same speed as TR, (3) an incremental treadmill test, and (4) an incremental cycle test. The following ventilatory data were collected every minute using an automated breath-by-breath system: pulmonary ventilation VE, l x min[-1]), oxygen uptake (VO2, ml x min(-1) x kg[-1]), carbon dioxide output (ml x min[-1]), respiratory equivalents for oxygen (VE/VO2) and carbon dioxide (VE/VCO2), respiratory exchange ratio (R) respiratory frequency (f, breaths x min[-1]), and tidal volume (ml). Heart rate (HR, beats x min[-1]) was monitored using a telemetric system. Biomechanical variables included stride length (SL) and stride frequency (SF) recorded on a video tape. The results showed that the following variables were significantly higher (analysis of variance, P < 0.05) for TR than for CR: VO2 [51.7 (3.4) vs 48.3 (3.9) ml x kg(-1) x min(-1), respectively], VE [100.4 (1.4) l x min(-1) vs 84.4 (7.0) l x min(-1)], VE/VO2 [24.2 (2.6) vs 21.5 (2.7)] VE/VCO2 [25.2 (2.6) vs 22.4 (2.6)], f[55.8 (11.6) vs 49.0 (12.4) breaths x min(-1)] and HR [175 (7) vs 168 (9) beats x min(-1)]. Moreover, the time needed to reach steady-state was shorter for HR and VO2 (1 min and 2 min, respectively) and longer for VE (7 min). In contrast, the biomechanical parameters, i.e. SL and SF, remained unchanged throughout TR versus CR. We conclude that the first minutes of the run segment after cycling in an experimental triathlon were specific in terms of VO2 and cardiorespiratory variables, and nonspecific in terms of biomechanical variables.

Aerobic metabolism and cardioventilatory responses in paraplegic athletes during an incremental wheelchair exercise

The aims of the present study were: (1) to assess aerobic metabolism in paraplegic (P) athletes (spinal lesion level, T4-L3) by means of peak oxygen uptake (VO2peak) and ventilatory threshold (VT), and (2) to determine the nature of exercise limitation in these athletes by means of cardioventilatory responses at peak exercise. Eight P athletes underwent conventional spirographic measurements and then performed an incremental wheelchair exercise on an adapted treadmill. Ventilatory data were collected every minute using an automated metabolic system: ventilation (l x min[-1]), oxygen uptake (VO2, l x min[-1], ml x min[-1] x kg[-1]), carbon dioxide production (VCO2, ml x min[-1]), respiratory exchange ratio, breathing frequency and tidal volume. Heart rate (HR, beats x min[-1]) was collected with the aid of a standard electrocardiogram. VO2peak was determined using conventional criteria. VT was determined by the breakpoint in the VCO2 - VO2 relationship, and is expressed as the absolute VT (VO2, ml x min[-1] x kg[-1]) and relative VT (percentage of VO2peak). Spirometric values and cardioventilatory responses at rest and at peak exercise allowed the measurement of ventilatory reserve (VR), heart rate reserve (HRr), heart rate response (HRR), and O2 pulse (O2 P). Results showed a VO2peak value of 40.6 (2.5) ml x min(-1) x kg(-1), an absolute VT detected at 23.1 (1.5) ml x min(-1) x kg(-1) VO2 and a relative VT at 56.4 (2.2)% VO2peak. HRr [15.8 (3.2) beats min(-1)], HRR [48.6 (4.3) beat x l(-1)], and O2 P [0.23 (0.02) ml x kg(-1) x beat(-1)] were normal, whereas VR at peak exercise [42.7 (2.4)%] was increased. As wheelchair exercise excluded the use of an able-bodied (AB) control group, we compared our VO2peak and VT results with those for other P subjects and AB controls reported in the literature, and we compared our cardioventilatory responses with those for respiratory and cardiac patients. The low VO2peak values obtained compared with subject values obtained during an arm-crank exercise may be due to a reduced active muscle mass. Absolute VT was somewhat comparable to that of AB subjects, mainly due to the similar muscle mass involved in wheelchair and arm-crank exercise by P and AB subjects, respectively. The increased VR, as reported in patients with chronic heart failure, suggested that P athletes exhibited cardiac limitation at peak exercise, and this contributed to the lower VO2peak measured in these subjects.

Validation of an incremental field test for the direct assessment of peak oxygen uptake in wheelchair-dependent athletes

The aim of this study was to validate an incremental field test performed by wheelchair-dependent (WD) athletes. Nine male paraplegic subjects (mean age 28.9 +/- 4.2 years) performed an incremental field test (FT) and a comparable laboratory test (LT) with their own usual wheelchairs. Both tests started with an initial speed of 4 km.hr(-1) and increased by increments of 1 km.hr(-1) every minute until volitional exhaustion. The FT was an adapted Léger and Boucher test (ALBT) and was conducted on a 400 m tartan field marked-off every 50 m with pylons. Ventilatory data were collected every 15 s using a portable telemetric system (Cosmed K2, JFB International, Italy). The LT was performed on an adapted treadmill (Sopur, Germany) and ventilatory data were collected every minute using a breath-by-breath automated system (CPX, Medical Graphics, MN, USA). The LT and the FT were not significantly different for duration (8 min 50 +/- 1 min 24 vs 9 min 55 +/- 29 s), percentage of maximal heart rate (HR, 86.2 +/- 3.9 vs 89.7 +/- 5.3%), maximal minute ventilation (VE, 101.6 +/- 28.5 vs 96.8 +/- 28.2 1.min(-1)) and peak oxygen uptake (VO2 peak, 39.7 + 7.3 vs 36.1 + 5.8 ml.kg(-1).min(-1) assessed with the CPX and the K2, respectively. We concluded that the FT proposed in the present study is a valid test for direct VO2 peak assessment in wheelchair athletes using a portable VO2 telemetric system. Nonetheless, the Léger and Mercier model equation did not accurately predict VO2 max and further investigation is needed to determine a valid VO2 max prediction equation for these subjects during the FT.

Anaerobic exercise components during the force-velocity test in sickle cell trait

Incremental exercise tests have shown no difference in exercise capacity (EC), maximal oxygen uptake (VO2max), and ventilatory threshold (VT) in subjects with sickle cell trait (SCT) when compared to controls with normal hemoglobin (Hb). Nevertheless, during long and strenuous exercise testing, subjects with SCT exhibit comparable EC but lower oxygen uptake (VO2). Consequently, specific metabolic adaptations in subjects with SCT have been suggested during endurance exercise, consisting of a slight "handicap" in oxygen consumption and compensation by the hypothetical development of a higher anaerobic metabolism. The purpose of the present study was to research differences in the anaerobic exercise performance, and the anaerobic exercise metabolism between 9 sedentary black males with SCT and 9 controls with normal Hb. The two groups of subjects were matched for morphological and hematological variables and for aerobic fitness. The subjects were tested using the force-velocity test (FV test) characterized by the repetition of 6-s maximal exercise bouts on a cycle ergometer. The anaerobic exercise performance parameters were peak anaerobic power (PAnP), maximal velocity (V0), and maximal braking force (F0). The anaerobic exercise metabolism parameters were blood lactate concentration at PAnP and peak lactate, and blood lactate kinetics during the FV test and the recovery period. The results indicated no significant difference between the SCT and control groups for PAnP (792.3 +/- 63.3 watts vs 763.8 +/- 52.5 watts), V0 (185.5 +/- 8.9 rev.min-1 vs 173.7 +/- 5.8 rev.min-1), F0 (17.1 +/- 1.2 kg vs 17.2 +/- 1.1 kg), blood lactate concentration at PAnP (5.3 +/- 0.9 mmol.l-1 vs 4.8 +/- 0.4 mmol.l-1), at peak lactate (7.0 +/- 0.9 mmol.l-1 vs 6.7 +/- 0.7 mmol.l-1), and blood lactate kinetics during the test and the recovery period. The present study indicated that sedentary subjects with SCT and controls with normal Hb had similar anaerobic exercise performance and similar anaerobic exercise metabolism. It did not confirm the hypothetical higher anaerobic metabolism suggested in subjects with SCT.

Exercise-induced death in sickle cell trait: role of aging, training, and deconditioning

The pathophysiological process of exercise-induced death in subjects with sickle cell trait (SCT) remains unclear. Concerning the cause of death, authors have suggested stressful environmental conditions such as altitude, heat and humidity, or abnormal patient conditions such as deconditioning, fatigue, and disease. These conditions are thought to lead to hypoxemia, hyperlactatemia, acidosis, dehydration, hyperthermia, or exercise-induced rhabdomyolysis, all of which may initiate sickle cell crisis, disseminated intravascular coagulation, myoglobinuria, and renal failure. We report the case of a 41-yr-old, healthy, and apparently well-conditioned subject with SCT who died during a cross-country race under normal environmental conditions in good weather (in terms of temperature and humidity). The medical and athletic history of the subject were unremarkable. We refer to an epidemiological study that reported a relation between age and exercise-induced sudden death in subjects with SCT. We then review the pathophysiological effects of aging in association with deconditioning and high-level training reported in the literature, particularly the decrease in aerobic metabolism in deconditioned subjects, and the exercise-induced hypoxemia in highly trained subjects. We discuss the consequences of deconditioning and high-level training in subjects with SCT during exercise, and conclude that these factors may be involved in the age-dependent risk of exercise-related sudden death in subjects with SCT.

Energy expenditure and cardiorespiratory responses at the transition between walking and running

We investigated whether the spontaneous transition between walking and running during moving with increasing speed corresponds to the speed at which walking becomes less economical than running. Seven active male subjects [mean age, 23.7 (SEM 0.7) years, mean maximal oxygen uptake (VO2max), 57.5 (SEM 3.3) ml.kg-1.min-1, mean ventilatory threshold (VTh), 37.5 (SEM3) ml.kg-1.min-1] participated in this study. Each subject performed four exercise tests separated by 1-week intervals: test 1, VO2max and VTh were determined; test 2, the speed at which the transition between walking and running spontaneously occurs (ST) during increasing speed (increases of 0.5 km.h-1 every 4 min from 5 km.h-1) was determined; test 3, the subjects were constrained to walk for 4 min at ST, at ST +/- 0.5 km.h-1 and at ST +/- 1 km.h-1; and test 4, the subjects were constrained to run for 4 min at ST, at ST +/- 0.5 km.h-1 and at ST +/- 1 km.h-1. During exercise oxygen uptake (VO2), heart rate (HR), ventilation (VE), ventilatory equivalents for oxygen and carbon dioxide (VE/VO2, VE/VCO2), respiratory exchange ratio (R), stride length (SL), and stride frequency (SF) were measured.(ABSTRACT TRUNCATED AT 250 WORDS)

Sickle cell trait as a limiting factor for high-level performance in a semi-marathon

Of 1506 black males participating in the first Abidjan semi-marathon, 123 subjects with sickle cell trait (SCT) were detected, i.e., 8.7%. Twenty-nine of these subjects with hemoglobin S (HbS) were ranked among the first 332 participants to finish the race, a percentage of 8.2. These percentages did not significantly differ from the prevalence of SCT observed in the general Ivory Coast population (12.0%). Only one subject with SCT was found among the 22 internationally-ranked athletes. The concentration of HbS found in this athlete (37.7%), his mean globular volume (87 fl), and his hemoglobin concentration (13.8 g/100 ml) suggest the coexistence of alpha-thalassemia with SCT. These results indicate that the percentage of SCT individuals participating in a semi-marathon is equal to the prevalence of SCT found in the local population. Furthermore, the general ranking of SCT individuals is comparable to that of non-SCT individuals. Nevertheless, at the level of internationally-ranked performance, no subject with SCT only, was ranked; the one ranked subject with SCT presented an associated alpha thalassemia. We thus hypothesize that SCT may be a limiting factor for high level performance in a semi-marathon and alpha-thalassemia, an enhancing factor for subjects with SCT to succeed in long distance races.

Maximal anaerobic power: relationship to anthropometric characteristics during growth

The purpose of this study was to determine the effects of age in relation to anthropometric characteristics upon maximal anaerobic power of legs in sixty-nine young boys aged 11 to 19 years. Maximal anaerobic power (Wmax) was measured by the force-velocity test. Lean body mass (LBM) was determined from all four skin-fold thickness measurements, leg volume (LV) was estimated by anthropometric method, and anthropometric measurements were used to determine total muscular mass (TMM). Wmax increased significantly (F = 44.1, p less than 0.001) between 11 and 19 years and was correlated with LV (r = 0.84) and TMM (r = 0.88). It was most highly correlated with LBM (r = 0.94), which best explained the percentage of the total variance of Wmax (88%). Normalized Wmax (Wmax/LBM) also increased significantly between 11 and 19 years (F = 21.9, p less than 0.001). In conclusion, Wmax determined by the force-velocity test was closely related to anthropometric characteristics, especially LBM, during the growth period. Furthermore, even when corrected for lean body mass, maximal anaerobic power was always found to increase. This suggests that other undetermined factors, in addition to the amount of lean tissue mass, may explain the increase of Wmax during the force-velocity test.

Sickle cell trait in Ivory Coast athletic champions, 1956-1989

Thirteen sickle cell trait carriers (SCTC) were found among 129 Ivory Coast champions or record holders in races for the period from 1956 to 1989 (10.1%). These 13 SCTC won 33 titles and national records (7.0%): 32 (12.5%) in races of 400 m or less and only one (0.004%) in races of 800 m or more, and the highest-performing SCTC won 8 titles and national records. A comparison with non-SCTC Ivory Coast champions shows that SCTC won significantly fewer titles than non-SCTC in long-distance races and that they won fewer titles during their careers.

[The Flack test: a test exploring the sinus function in athletes. Apropos of 351 tests]

A standardized Flack's test with continuous electrocardiographic recording was performed in 351 moderately trained athletes (317 men and 34 women; mean age 23.7 years). The test gave normal results in 310 subjects (88.3%). Tachycardia in excess of 100 beats/min was observed in 12 subjects (3.4%), and 56 abnormalities which were not present on previous ECG recordings at rest were noted in 29 subjects (8.3%); 27 of these abnormalities appeared immediately after a previous one. Out of these 56 abnormalities, 26 (44.6%) were associated with sinus dysfunction: sinus bradycardia in 8 cases, second degree sinoatrial block in 2 cases, third degree sinoatrial block in 3 cases and sinus arrest in 13 cases. In 16 cases of third degree sinoatrial block or sinus arrest escape rhythms were observed, including coronary sinus rhythm (3), junctional rhythm (12) and accelerated idioventricular rhythm (1). Five of the 56 abnormalities (8.9%) were disorders of conduction, i.e. first or second degree atrioventricular block, atrioventricular dissociation and blocked P waves. These disorders are known to be frequently associated with sinus dysfunction. In 9 out of 56 abnormalities (16.1%) disorders of excitability were present as atrial, junctional and ventricular extrasystoles. In 8 subjects the Flack's test resulted in the disappearance of disorders of conduction or excitability of the "athlete" type present at rest, as the Ruffier-Dickinson test, or the cycloergometric exercise test.(ABSTRACT TRUNCATED AT 250 WORDS)

[Cardiac hypertrophy, dilatation and performance in top athletes]

The authors have studied three groups of patients: 12 reference patients (REF) leading a sedentary life; 22 athletes of international fame, practising an endurance sport (END), including 10 long distance and middle-distance runners, 12 cyclists and 12 top (RES) athletes practising a resistance sport i.e. 12 sprinters. There is no age difference between the two groups. The RES have a larger body area than the REF and END. The cardiac frequency is lowered in the athletes without any difference between RES and END. There is no difference as far as the athletes' blood pressure is concerned. On the EKG, the Sokoloff index is significantly higher in END than in REF and RES. Sonographic data were especially analyzed. END present a hypertrophic myocardium and ventricular dilatation. The hypertrophy, more assymmetrical than that of RES, is more marked at the level of the septum. There is a non-significant tendency toward an excentric hypertrophy. RES present a marked hypertrophy with little or no dilatation. This hypertrophy is more symmetrical and concentric than in END patients. As far as the pump function is concerned (FR, FE, VES): it is not altered in RES (this fact is found in the literature). On the contrary, in END patients, the pump function (FR, FE) is diminished (this fact is debated in the literature), in spite of an increased systolic ejection volume. The total contraction function is not altered in RES nor in END patients. An increased septal contraction rate is noted, which is significant in RES patients and non-significant in END patients.(ABSTRACT TRUNCATED AT 250 WORDS)