Continuous Incremental Test Research Articles

Is test specificity the issue in assessing aerobic fitness and performance of runners? A systematic review.

Various tests have been developed to evaluate aerobic fitness and performance of runners. However, a systematic understanding of which methods are more accurate is necessary to provide coaches and the sports sciences community with useful and confident outcomes. This study aims to summarize the evidence regarding the validity, reliability and sensitivity of tests for measuring aerobic fitness and performance in runners of several background of training. A systematic search was conducted of Web of Science, PubMed and Scopus up to 31st December 2022 according to PRISMA statement guidelines. Studies that reported findings about tests covering maximal aerobic speed, final velocity achieved during the test, average running speed or other method of evaluating the reference speed during the test were included. We evaluated the risk of bias in the included articles using the Risk of Bias Assessment Tool for Nonrandomized Studies (RoBANS). The tests were categorized into continuous incremental tests, intermittent tests and time-trial test. A total of 23 studies met eligibility criteria. These studies contained three background of training: track and road runners (N.=15), trail runners (N.=7) and inexperienced runners (N.=1). Criterion validity was assessed in 73% of the studies, while only 41% of studies examined convergent validity. The majority of the reviewed studies (87%) ignored test-retest reliability. Test sensitivity was not reported in any study. At least one aerobic fitness and performance test was identified for each types of background of training. However, some methodological aspects were not provided in the included articles. Most studies examined at least one aspect of validity (i.e., criterion or convergent-related validity), whilst few studies investigated test-retest reliability. Researchers and practitioners can use the information provided in this systematic review to select appropriate tests.

Agreement of maximal lactate steady state with critical power and physiological thresholds in rowing

ABSTRACT The aim of this study was threefold: (a) to compare the maximal lactate steady state (MLSS) with critical power (CP); (b) to describe the relationship of MLSS with rowing performances; and (c) to verify the agreement of MLSS with several exercise intensity thresholds in rowers. Fourteen male rowers (mean [SD]: age = 26 [13] years; height = 1.82 [0.05] m; body mass = 81.0 [7.6] kg) performed on a rowing ergometer: (I) discontinuous incremental test with 3 min stages and 30-s recovery intervals (INC3min); (II) continuous incremental test with 60-s stages (INC1min); (III) two to four constant workload tests to determine MLSS; and (IV) performance tests of 500, 1000, 2000 and 6000 m to determine CP. Twenty-seven exercise intensity thresholds based on blood lactate, heart rate and ventilatory responses were determined by incremental tests, and then compared with MLSS. CP (257 [38] W) was higher than MLSS (187 [25] W; p < 0.001), with a very large mean difference (37%), large typical error of estimate (14%) and moderate correlation (r = 0.48). Despite the correlations between MLSS and most intensity thresholds (r > 0.70), all presented low correspondence (TEE > 5%), with a lower bias found between MLSS and the first intensity thresholds (−12.5% to 4.1%). MLSS was correlated with mean power during 500 m (r = 0.65), 1000 m (r = 0.86) and 2000 m (r = 0.78). In conclusion, MLSS intensity is substantially lower than CP and presented low agreement with 27 incremental-derived thresholds, questioning their use to estimate MLSS during rowing ergometer exercise. Highlights MLSS was substantially lower than CP in rowing exercise with a mean difference of 37%, much larger than the difference commonly found in running and cycling exercise (i.e., ?10%). A clear disagreement was reported between MLSS and 27 physiological thresholds determined in different incremental tests. There is a positive association of MLSS with 500, 1000 and 2000 m rowing ergometer performance tests.

The Hoff circuit test is more specific than an incremental treadmill test to assess endurance with the ball in youth soccer players.

The assessment of aerobic endurance is important for training prescription in soccer, and is usually measured by straight running without the ball on a track or treadmill. Due to the ball control and technical demands during a specific soccer test, the running speeds are likely to be lower compared to a continuous incremental test. The aim of the present study was to compare the heart rate (HR), rating of perceived exertion (RPE) and speeds corresponding to 2.0 mmol∙L-1, 3.5 mmol∙L-1, lactate threshold (Dmax method) and peak lactate determined in the laboratory and in the Hoff circuit soccer-specific test. Sixteen soccer players (16±1 years) underwent two incremental tests (laboratory and Hoff circuit tests). The speeds were significantly higher in the treadmill test than on the Hoff circuit (2.0 mmol∙L-1: 9.5±1.2 and 8.1±1.0 km∙h-1; 3.5 mmol∙L-1: 12.0±1.2 and 10.2±1.1 km∙h-1; Dmax: 11.4±1.4 and 9.3±0.4 km∙h-1; peak lactate: 14.9±1.6 and 10.9±0.8 km∙h-1). The HR corresponding to 3.5 mmol∙L-1 was significantly higher on the Hoff circuit compared to the laboratory test (187.5±18.0 and 178.2±17.6 bpm, respectively; P <0.001), while the RPE at the last incremental stage was lower on the Hoff circuit (P < 0.01). The speeds during the Hoff specific soccer test and the HR corresponding to 2.0 mmol∙L-1, 3.5 mmol∙L-1 and Dmax/threshold were different compared with the laboratory test. The present study shows that it is possible to assess submaximal endurance related variables specifically in soccer players.

Effects of two field continuous incremental tests on cardiorespiratory responses in Standardbred trotters.

In humans, cardiorespiratory responses are widely evaluated from field incremental exercise tests. On the contrary, equine exercise physiology faces a huge lack of oxygen consumption measurements (VO2) in field conditions due to technical concerns. The aim of this study was to test the effects of two incremental continuous field tests on cardiorespiratory responses in Standardbred trotters. The two protocols were realized at trot and ended when horses galloped. The tests started at 4.2 m/s (T1) and 6.4 m/s (T2), with speed increments of 1.4 m/s every 3 min for T1 and 0.8 m/s every 2 min for T2. Velocity (v), heart rate (HR) and gas exchanges were recorded continuously, and blood lactate concentration [La(-)] was measured before and after tests. Values recorded at the end of the tests were considered as peak values. The vpeak values were 10.6 ± 0.3 and 10.7 ± 0.7 m/s for T1 and T2 respectively. Horses reached higher VO2peak (T1: 116.6 ± 11.5 ml/min/kg; T2: 88.9 ± 10.2 ml/min/kg; p < 0.05) and HRpeak (T1: 217 ± 5 bpm; T2: 209 ± 3 bpm; p < 0.05) during T1 compared with T2. T1 was significantly longer than T2 (17.5 ± 1.9 vs. 12.9 ± 1.6 min respectively, p < 0.01), and the number of steps entirely ran tended to be different (T1: 5.6 ± 0.6; T2: 6.2 ± 0.8, p = 0.07). Compared to T2, the design of T1 appeared easier to implement and allowed higher cardiorespiratory responses. The relationship between HR-VO2 obtained through T1 gave a better correlation between the two variables than T2. These findings suggest that T1 might be better than T2 for evaluating cardiorespiratory adaptations to exercise and for estimating aerobic energy expenditure in exercising trotters.

Mechanical Work and Long-Distance Performance Prediction: the Influence of Allometric Scaling

The purpose of this study was to examine the effect of allometric scaling on the relationship between mechanical work and long-distance running performance in recreational runners. Fourteen recreational long-distance runners (male, mean ± SD - age: 29 ± 7 years; body mass: 70.0 ± 10.2 kg; body height: 1.71 ± 0.07 m; maximal oxygen uptake: VO2max 52.0 ± 4.9 ml·kg−1·min−1) performed two tests: a continuous incremental test to volitional exhaustion in order to determine VO2max, and a 6-minute running submaximal test at 3.1 m·s−1, during which segments in the sagittal plane were recorded using a digital camera and the internal (Wint), external (Wext) and total (Wtot) mechanic work, in J·kg−1·m−1, was subsequently calculated. The results indicated a significant correlation between mechanical work and performance, however, the strongest correlations were observed when allometric exponents were used (respectively for Wint, Wext and Wtot; non allometric vs. allometric scaling defined by literature (0.75) or determined mathematically (0.49): r = 0.38 vs. r = 0.44 and r = 0.50; r = 0.80 vs. r = 0.83 and r = 0.82; r = 0.70 vs. r = 0.77 and r = 0.78). These results indicate that mechanical work could be used as a predictor of recreational long-distance performance and an allometric model may improve this prediction.

Comparison Between Three Different Endurance Tests in Professional Soccer Players

The aims of this study were (a) to assess and correlate interval shuttle run test (ISRT) performance, maximum oxygen uptake (V[Combining Dot Above]O(2)max), running economy (RE), running velocity at the first rise in blood lactate concentrations above baseline (vLT) and running velocity at 4 mmol·L(-1) blood lactate concentration (v4) in professional soccer players and (b) to investigate whether a correlation exists between the respective results of time to exhaustion (T(lim)) from continuous and intermittent endurance tests, respectively. Eleven male professional field soccer players (mean ± SD: age 23.8 ± 3.0 years, V[Combining Dot Above]O(2)max 58.2 ± 4.9 ml·kg(-1)·min(-1)) completed a continuous Incremental Test with lactate measurements to determine vLT and v4, a continuous Ramp Test with gas exchange analysis to determine V[Combining Dot Above]O(2)max and RE, and an intermittent ISRT to determine intermittent endurance capacity during the first week of preseason preparation. There were significant correlations between ISRT performance and V[Combining Dot Above]O(2)max (r = 0.70, p < 0.05), and between T(lim) in both continuous endurance tests (r = 0.89, p < 0.01). Between all other variables no significant correlations were found overall (best r = 0.60, p > 0.05). The assessment of all values of V[Combining Dot Above]O(2)max, RE, vLT, and v4 should be included when investigating aerobic endurance performance among groups or over time in professional soccer players. Although V[Combining Dot Above]O(2)max, RE, vLT, and v4 have been regarded as important factors of aerobic performance in endurance related sports, the present data revealed that V[Combining Dot Above]O(2)max was the only factor, which correlated with intermittent endurance capacity in professional soccer players. Hence, V[Combining Dot Above]O(2)max should be increased through soccer-specific training interventions including universal agility components. The T(lim) in continuous and intermittent endurance tests differs and is therefore an independent endurance performance factor in professional soccer players.

Cycle Ergometer Tests in Children With Cystic Fibrosis: Reliability and Feasibility

The aim of this study was to assess the reliability and feasibility of cycle ergometer tests in young children with cystic fibrosis (CF). Children with CF aged 6-11 years and with stable lung disease performed two cycle ergometry tests (intermittent sprint and continuous incremental) on two occasions 1 week apart. Reliability was assessed using repeated-measures ANOVA. Bias was considered to be significant at P < 0.05 level and a coefficient of variation (CV) below 10% was considered acceptable. Feasibility and acceptability data were also collected. Sixteen children with CF completed the study: (9M:7F), 8.7(1.8) years, FEV(1) %predicted: 88.1(17.4). Power measurements recorded during the intermittent sprint test demonstrated significant bias over days (P < 0.05) and CVs were between 10% and 15%. Peak work capacity recorded during the continuous incremental test was reliable (bias P < 0.05, CV < 10%), as was heart rate and SpO(2) recorded during both tests (bias P < 0.05, CV < 10%). No problems were experienced in administering the tests and all children completed both tests on two separate occasions. There was a mixed response to questions on acceptability of tests. This is the first study to provide information on the reliability of performance measures recorded during an intermittent sprint protocol (peak power) and a continuous incremental cycle ergometry (peak work capacity) in children with CF.

Self-regulation of exercise intensity by estimated time limit scale

The purpose of this study was to evaluate the validity of the estimated time limit scale (ETL), which deals with a subjective prediction of how long the current exercise intensity can be maintained, for regulating exercise intensity using typical estimation-production procedure. Thirty-six male athletes performed a continuous incremental test and two discontinuous tests with randomized workloads (estimation tests at 65, 75, 85 and 95% of the maximal power output, and production tests: subjects have to use the ETL values which were collected for each power during the estimation test in order to manually product the corresponding workload). The intraclass correlation coefficient for the power output between estimation and production tests is good for exercises at 75, 85 and 95% MAP (0.81, 0.85 and 0.96, respectively). Moreover, mean differences both for power output and cardiorespiratory data were not significantly different between estimation and production tests for exercises at 85 and 95% MAP. Consequently, the validity to prescribe an exercise intensity from the ETL scale is attested in these athletes particularly for high exercise intensities on cycloergometer.

Prediction of Time to Exhaustion in Competitive Cyclists From a Perceptually Based Scale

Prediction of time to exhaustion in competitive cyclists from a perceptually based scale. We have tested the validity of the estimated time limit (ETL) scale to predict an exhaustion time (T(lim)) from values stemming from incremental and randomized constant workloads tests on a cycle ergometer. Twenty-five cyclists performed 1 continuous incremental test, 1 discontinuous test with randomized workloads, and 1 constant power output test at 90% of maximal aerobic power (MAP) to exhaustion. Estimated time limits at 90% MAP during the incremental test and the test with randomized workloads were calculated from exponential relationships between power and ETL using the same 4 workloads. Real measured T(lim) during the constant power output test was converted into ETL values (called measured ETL). The differences between the calculated and measured ETLs were examined. Estimated time limits calculated at 90% MAP during the incremental and randomized tests corresponded to 14 minutes 56 seconds and 10 minutes 14 seconds, whereas measured ETL was equal to 11 minutes 19 seconds ± 3 minutes 40 seconds. The results showed a nonsignificant difference between calculated and measured ETLs. However, the mean differences between the measured ETL values during the constant test performed at the same intensity were -1.3 ± 2.9 and 0.3 ± 3.0 for the incremental and the randomized constant workloads tests, respectively. Consequently, the use of ETL calculated at 90% MAP during the test with randomized constant workloads may be preferable to predict the accurate T(lim). Moreover, it would seem that high-level cyclists, who were more consciously attuned to their bodies and their own effort sense, were more accurate in their prediction than low-level cyclists. It is concluded that the randomized constant workloads test that is both shorter and less strenuous would be more convenient for high-level athletes.

Influence of successive bouts of fatiguing exercise on perceptual and physiological markers during an incremental exercise test

The purpose of this study was to examine the effects of a succession of fatiguing stages, on ratings of perceived exertion (RPE) and estimated time limits (ETL) during an incremental exercise test. Twenty-seven cyclists performed a continuous incremental test and a discontinuous test with randomized workloads. A linear mixed model was used to compare the RPE, ETL, respiratory gas, heart rate, and blood data obtained during the two exercise tests. RPE and ETL were not significantly different between the tests. Ventilation, breathing frequency, heart rate, and blood lactate concentration were significantly higher during the last incremental test workloads. In conclusion, although the incremental exercise test generated higher cardiorespiratory and muscular workloads than observed during the randomized exercise test, most likely due to a greater fatiguing process, these higher workloads did not influence the perceptual response.

Estimation of Oxygen Uptake during Fast Running Using Accelerometry and Heart Rate

Previous investigations have reported that accelerometer counts plateau during running at increasingly faster speeds. To assess whether biomechanical and/or device limitations cause this phenomenon and the feasibility of generating oxygen uptake (.VO2) prediction equations from the combined use of accelerometry and heart rate during walking and running. : Sixteen endurance-trained subjects completed two exercise tests on a treadmill. The first was a continuous incremental test to volitional exhaustion to determine ventilatory threshold and peak .VO2. The second was a discontinuous incremental exercise test while walking (3, 5, and 7 km.h(-1)) and running (8, 10, 12, 14, 16, 18, and 20 km.h(-1), or until volitional exhaustion). Subjects completed 3 min of exercise at each speed, followed by 3-5 min of recovery. Activity counts from uni- and triaxial accelerometers, heart rate, and gas exchange were measured throughout exercise. All accelerometer outputs rose linearly with speed during walking. During running, uniaxial accelerometer outputs plateaued, whereas triaxial output rose linearly with speed up to and including 20 km.h(-1). Prediction of .VO2 during walking and running using heart rate (R2 = 0.42 and 0.59, respectively), accelerometer counts (R2 = 0.48-0.83 and 0.76, respectively), the combined methodologies (R2 = 0.54-0.85 and 0.80, respectively), and the combined methodologies calibrated with individual data (R2 = 0.99-1.00 and 0.99, respectively) was completed by linear regression. Uni- and triaxial accelerometer outputs have a linear relationship with speed during walking. During running, uniaxial accelerometer outputs plateau because of the biomechanics of running, whereas triaxial accelerometer output has a linear relationship. The combined methodologies predict .VO2 better than either predictor alone; a subject's individually calibrated data further improves .VO2 estimation.

Scaling behaviour of in athletes and untrained individuals

Objective: The present study analysed the allometric relationship (MR = a · Mb) between human metabolic rate (MR), ranging from resting to maximal metabolic conditions, and body mass (M ), both in athletes of different specialization and untrained individuals.Subjects and methods: Two hundred and seventy male athletes and 43 untrained men performed a continuous incremental test to volitional exhaustion on a motorized treadmill. Metabolic rate (i.e. ) was measured during resting (), sub-maximal (walking at 5 km h−1 ; running at 7.5 km h−1 ; ventilatory anaerobic threshold ) and maximal exercise conditions (maximum oxygen uptake ).Results: A significant difference ( p < 0.001) in the MR–body mass relationships between athletes and controls was found. For the control group, the mass exponent b exhibited a non-significant ( p = 0.37) increase with increasing metabolic demand (b = 0.69, 0.76, 0.76, 0.84, and 0.89, for , , , , and , respectively). In contrast, the corresponding mass exponent for the athletic group significantly ( p < 0.01) decreased when moving from resting to maximal metabolic conditions (b = 0.98, 0.88, 0.80, 0.69, and 0.67).Conclusion: These results indicate that the recently proposed allometric cascade model may be valid in describing the scaling behaviour of MR in untrained individuals, but not in athletes of different specialization.

Confirmation of Treadmill VO2max in Sprinters and Long Distance Runners

A plateau in oxygen uptake (VO2) despite an increase in work rate is often not observed during continuous incremental exercise tests. Indirect criteria including respiratory exchange ratio (R > 1.10) and blood lactate concentration ([La-] > 8.0 mM) are frequently used to confirm maximal oxygen uptake (VO2max) in the absence of a plateau in VO2. Recently, a test to directly confirm VO2peak was developed for healthy males performing cycle ergometry (J Appl Physiol 100: 764-770, 2006). PURPOSE: The purpose of this investigation was to determine whether long distance runners and sprinters routinely display a VO2 plateau during continuous incremental treadmill tests, and if not, whether the highest VO2 observed was in fact VO2max. METHODS: Nine male long distance runners (age 21 ± 1 yrs, VO2max 71.0 ± 2.8 mL·kg−1·min−1) and six male sprinters (age 26 ± 3 yrs, VO2max 55.9 ± 5.8 mL·kg−1·min−1) ran to volitional exhaustion at a constant treadmill speed previously determined to elicit 4 mM blood [La-]. This continuous incremental test consisted of two-minute stages with 2% grade increments. A VO2 plateau was defined as less than half the expected increase in VO2 between the last two completed stages. Following a 15 minute recovery period, subjects performed a constant work rate test to exhaustion at a steeper grade. Data were analyzed by paired-samples t-test. RESULTS: None of the long distance runners and one of the sprinters achieved a plateau on the continuous incremental test. However, by combining the data from the continuous incremental test and the constant work rate test, all subjects exhibited a discontinuous plateau in VO2. Peak VO2 on the continuous incremental test for the long distance runners (70.6 ± 2.8 mL·kg−1·min−1) was not significantly different (P = 0.12) from peak VO2 on the constant work rate test (69.2 ± 2.5 mL·kg−1·min−1). Peak VO2 on the continuous incremental test for the sprinters (55.6 ± 5.9 mL·kg−1·min−1) was not significantly different (P = 0.09) from peak VO2 on the constant work rate test (53.4 ± 5.0 mL·kg−1·min−1). CONCLUSIONS: Trained competitive sprinters and long distance runners do not routinely exhibit a plateau at VO2max during continuous incremental treadmill tests. Peak VO2 on a continuous incremental treadmill test can be directly confirmed as VO2max by performing an additional higher work rate test following a short rest.

Effects of High- vs Low-Cadence Interval Training on Physiology and Performance of Competitive Cyclists

PURPOSE. High-resistance interval training produces substantial gains in sprint and endurance performance when added to the usual training of cyclists in the competitive phase of a season. Here we report the effect of changing the cadence of the intervals on performance and physiology. METHODS: We randomised 18 road cyclists to a low-cadence (60–70 min−1) or high-cadence (110–120 min−1) group for 4–5 wk of training. Both groups replaced part of their usual training with eight 30-min sessions consisting of three sets of explosive single-leg jumps (20 for each leg) alternating with three sets of high-intensity cycling sprints (5x 30 s with 30-s recoveries between repetitions) performed on a training ergometer with resistance set individually to achieve the desired cadence. Saliva samples were collected before and after each training session to assay testosterone concentration. Performance and physiological measures, obtained on a cycle ergometer before and after the intervention, were mean power in a 60-s time trial and the following measures obtained from a continuous incremental test: peak power, maximum oxygen uptake, 4-mM lactate power, fractional utilization of maximum oxygen uptake at 4-mM lactate, and exercise economy. RESULTS: Power output in the interval sets over the training period increased by 11.0% ± 5.4% (mean ± SD) in the low-cadence group and by 8.3% ± 2.1% in the high-cadence group. Testosterone concentration increased in each training session, by 96% ± 25% (mean ± between-session SD) in the low-cadence group and by 62% ± 20% in the high-cadence group. There were substantial enhancements in performance in the low-cadence group (6–11 %) and high-cadence group (2–3%). Mean changes (±90% confidence limits) in the low-cadence group relative to the high-cadence group were: 60-s mean power, 2.5% (±4.8%); peak power, 3.6% (±3.7%); maximum oxygen uptake, 3.2% (±4.2%); 4-mM lactate power, 7.0% (±5.9%); fractional utilization, 0.9% (±4.9%); and exercise economy at 50% and 80% of pre-testpeak power, 5.1% (±4.9%) and 0.2% (±4.1%) respectively. CONCLUSION. Low-cadence interval training is probably more effective than high-cadence training in improving performance of well-trained competitive cyclists. The differences in performance could be due to different effects of the two training cadences on economy and maximum oxygen uptake, possibly mediated in part by training-induced changes in testosterone.

Accumulated Oxygen Deficit and VO2max Plateau on a Continuous Incremental Test

Accumulated Oxygen Deficit and VO2max Plateau on a Continuous Incremental Test

Accumulated oxygen deficit on a continuous incremental exercise test

Exercise tolerance is limited by maximal accumulated oxygen deficit (MAOD) for constant work rate exercise tests (CW) in the severe intensity domain (J Appl Physiol 64: 50–60, 1988). Unpublished data from our laboratory indicate that endurance trained subjects performing a continuous incremental test (CI) reach exhaustion in concert with MAOD. The purpose of the present investigation was to determine whether untrained subjects also achieve MAOD on an exhaustive CI. On a motorized treadmill, eight recreationally active males (VO2max 50.9 ± 6.5 mL×kg−1×min−1) completed: a) sub-maximal tests (SMT) to establish the grade-VO2 relationship at the speed that elicited 4 mM blood [lactate] (S4), b) a CI at S4 to determine VO2max and accumulated oxygen deficit (AODCI), c) a CW to confirm VO2max, and d) a CW that induced exhaustion in 2–4 min to ascertain MAOD. O2 demand was linearly extrapolated from the VO2 response at each grade on the SMT. Data were analyzed by repeated measures ANOVA. Each subject manifested blood [lactate] > 8.0 mM and RER > 1.10 on the CI. Peak VO2 on the CI (3.93 ± 0.56 L×min−1) tended (p = 0.054) to be greater than on the CW (3.85 ± 0.53 L×min−1). AODCI (38.1 ± 21.0 mL×kg−1) was significantly lower (p < 0.05) than MAOD (50.3 ± 16.6 mL×kg−1). This may be due to difficulties in the prediction of O2 demand or differences in the mechanisms of exhaustion in untrained and endurance trained subjects. Estimation of AODCI is confounded in some cases by non-linear VO2 responses, akin to a slow component, driving the measured VO2 in excess of O2 demand in the late stages of the CI.

EMG Activity does not Change During a Time Trial in Competitive Cyclists

The purpose of the present study was to measure the electromyographic (EMG) activity of four lower limb muscles and the propulsive torque during a cycling time-trial (TT). Nine competitive cyclists (V.O (2max): 73.8 +/- 5.3 ml . min (-1) . kg (-1)) performed two tests separated over a one-week period on a friction-load cycle ergometer equipped with a SRM crankset scientific system: 1) a continuous incremental test for the determination of the peak power output (PPO); and 2) a 30-min TT test at a self-selected work intensity. The EMG activity of the vastus medialis (VM), the rectus femoris (RF), the biceps femoris (BF), and the gastrocnemius medialis (GAS), and the propulsive torque were recorded every 5 min for 10 s. There was no time effect on the power output, the pedalling cadence, and the mean propulsive torque. The EMG activity of the VM and the RF muscles was unchanged during the TT (p > 0.05). The EMG activity of the two knee flexor muscles (BF and GAS) tended to increase with time but it was not significant (p > 0.05). The EMG/torque of the VM and the RF muscles tended to decrease with time but it was not significant (p > 0.05). The lack of increase in the EMG activity of the four investigated muscles seems to indicate that the subjects performed the TT test at a muscular work steady-state.

The Isocapnic Buffering Phase and Mechanical Efficiency: Relationship to Cycle Time Trial Performance of Short and Long Duration

The purpose of this study was to determine the relationship between the isocapnic buffer (beta(isocapnic)) and hypocapnic hyperventilation (HHV) phases as well as performance in a short (20-min) and long (90-min) time trial (TT) in trained athletes. In addition, gross (GE, %) and delta (deltaE, %) efficiency were calculated and the relationship between these variables and the average power output (W) in each TT was determined. Thirteen male endurance athletes (Mean +/- SD age 31 +/- 6 yrs; body mass 75.6 +/- 6.3 kg; height 185 +/- 6 cm) completed a continuous incremental test to exhaustion for determination of the beta(isocapnic) and HHV phases. A second submaximal test was used to determine GE and deltaE. The average power output (W) was measured in a 20-min and 90-min cycling TT. The beta(isocapnic) phase (W) was significantly correlated to the average power output (W) in the 20-min TT (r = 0.58; p < 0.05), but not in the 90-min TT (r = 0.28). The HHV phase (W) was not significantly correlated to the average power output in the 20-min or 90-min TT. No significant correlation was found for GE or for deltaE and performance in the TT. The data from this study shows that beta(isocapnic) together with HHV is not likely to be a useful indicator of cycle TT performance of 20- to 90-min duration. Furthermore, GE and deltaE determined from a submaximal incremental stepwise test are not related to cycling TT performance of different duration.

Anaerobic contribution to the time to exhaustion at the minimal exercise intensity at which maximal oxygen uptake occurs in elite cyclists, kayakists and swimmers.

Using 23 elite male athletes (8 cyclists, 7 kayakists, and 8 swimmers), the contribution of the anaerobic energy system to the time to exhaustion (t(lim)) at the minimal exercise intensity (speed or power) at which maximal oxygen uptake (VO2max) occurs (IVO2max) was assessed by analysing the relationship between the t(lim) and the accumulated oxygen deficit (AOD). After 10-min warming up at 60% of VO2max, the exercise intensity was increased so that each subject reached his IVO2max in 30 s and then continued at that level until he was exhausted. Pre-tests included a continuous incremental test with 2 min steps for determining the IVO2max and a series of 5-min submaximal intensities to collect the data that would allow the estimation of the energy expenditure at IVO2max. The AOD for the t(lim) exercise was calculated as the difference between the above estimation and the accumulated oxygen uptake. The mean percentage value of energy expenditure covered by anaerobic metabolism was 15.2 [(SD 6)%, range 8.9-24.1] with significant differences between swimmers and kayakists (16.8% vs 11.5%, P < or = 0.05) and cyclists and kayakists (16.4% vs 11.5%, P < or = 0.05). Absolute AOD values ranged from 26.4 ml.kg-1 to 83.6 ml.kg-1 with a mean value of 45.9 (SD 18) ml.kg-1. Considering all the subjects, the t(lim) was found to have a positive and significant correlation with AOD (r = 0.62, P < or = 0.05), and a negative and significant correlation with VO2max (r = -0.46, P < or = 0.05). The data would suggest that the contribution of anaerobic processes during exercise performed at IVO2max should not be ignored when t(lim) is used as a supplementary parameter to evaluate specific adaptation of athletes.

MAXIMAL AEROBIC POWER IN TRIATHLETES DURING SWIMMING, CYCLING, AND RUNNING754

While a few authors have compared the maximal oxygen consumption(VO2max) of triathletes during running, cycling, and swimming, all previous investigators have used tethered swimming. No researchers have reported this comparison using a swimming treadmill (flume) which better represents the open water swimming encountered during a triathlon. Therefore, the purpose of this study was to compare maximal oxygen consumption during flume swimming, stationary cycling, and treadmill running in highly trained competitive triathletes. Seven healthy male triathletes (Age=32±11 yrs, Ht=178±5 cm, Wt=68±6 kg, Fat%=8.4±3.8%) were recruited for this study. On separate days, subjects performed a continuous incremental test to volitional exhaustion to determine maximal oxygen consumption(L·min-1), maximal ventilation (VEmax;L·min-1) and maximal heart rate (HRmax:beats·min-1) for each mode of exercise. The findings can be seen in the followingtable: Despite the varied athletic background of these triathletes, all subjects elicited their highest VO2max during running, and lowest during swimming. This was represented by a 6% and 18% greater VO2max during the run as compared to the cycle and swim, respectively. These data indicate that a triathlete's VO2max varies in each event despite being well conditioned in all three.