Optimal velocity for maximal power production in non-isokinetic cycling is related to muscle fibre type composition

To determine whether power-velocity relationships obtained on a nonisokinetic cycle ergometer could be related to muscle fibre type composition, ten healthy specifically trained subjects (eight men and two women) performed brief periods of maximal cycling on a friction loaded cycle ergometer. Frictional force and flywheel velocity were recorded at a sampling frequency of 200 Hz. Power output was computed as the product of velocity and inertial plus frictional forces. Force, velocity and power were averaged over each down stroke. Muscle fibre content was determined by biopsy of the vastus lateralis muscle. Maximal down stroke power [14.36 (SD 2.37)W·kg^–1] and velocity at maximal power [120 (SD 8) rpm] were in accordance with previous results obtained on an isokinetic cycle ergometer. The proportion of fast twitch fibres expressed in terms of cross sectional area was related to optimal velocity (r = 0.88, P < 0.001), to squat jump performance (r = 0.78, P < 0.01) and tended to be related to maximal power expressed per kilogram of body mass (r = 0.60, P = 0.06). Squat jump performance was also related to cycling maximal power expressed per kilogram of body mass (r = 0.87, P < 0.01) and to optimal velocity (r = 0.86, P < 0.01). All these data suggest that the nonisokinetic cycle ergometer is a good tool with which to evaluate the relative contribution of type II fibres to maximal power output. Furthermore, the strong correlation obtained demonstrated that optimal velocity, when related to training status, would appear to be the most accurate parameter to explore the fibre composition of the knee extensor muscle.     

Recovery of the torque-velocity relationship after short exhausting cycling exercise

The effects of fatigue upon the torque-velocity (T-ω) relationship in cycling were studied in 11 subjects. Fatigue was induced by short exhausting exercise, on a cycle ergometer, consisting of 4 all-out sprints without recovery. The linear (T-ω) relationship was determined during each all-out sprint, before, during and after the exhausting exercise. The kinetics of the T-ω relationship had permitted the study of the recovery of optimal torque, optimal velocity and their corresponding maximal power outputs (P _max), 30?s or 1?min after the short exhausting exercise. Fatigue induced a parallel shift to the left of the T-ω relationship which was partly reversed by a parallel shift to the right during recovery. After 30?s recovery optimal velocity, optimal torque and P _max were slightly lower than the corresponding values before the exhausting exercise; after 1-min optimal velocity and optimal torque had recovered 99% and 97% of their initial values. These mechanical data suggested that the causes of exhaustion were processes that allowed fast recovery of both optimal velocity and optimal torque.     

Influence of two pedalling rate conditions on mechanical output and physiological responses during all-out intermittent exercise

The purpose of this study was to investigate the effect of two cycling velocities on power output and concomitant metabolic and cardiorespiratory responses to repeated all-out exercises. Mean power output (P _m), total work (W _tot), total oxygen consumption (VO_2tot) and blood lactate accumulation (Δ[La]_b) were evaluated in 13 male subjects who performed two series of twelve 5-s bouts of sprint cycling. Recovery periods of 45-s were allowed between trials. One series was executed at optimal velocity (V _opt: velocity for greatest power) and the other one at 50% V _opt (0.5V _opt). Velocities obtained in these conditions were V_opt=116.6 (4.7) rpm; 0.5V_opt=60.6 (4.9) rpm. After a phase of adaptation in oxygen uptake in the first part of the series, the data from the 6th to the 12th sprint were as follows: P _m, 924.6 (73.9) versus 689.2 (61.8) W; W _tot, 29.95 (4.14) versus 22.04 (3.17) kJ; VO_2tot, 12.80 (1.36) versus 10.58 (1.37) l; Δ[La]_b, 2.72 (1.22) versus 0.64 (0.79) mmol.l⁻¹, respectively (P<0.001). Both W _tot and VO_2tot were consistently higher at optimal velocity (+21 and +35.8%, respectively). The present findings demonstrate that during intermittent short-term all-out exercise requiring maximal activation, the energy turnover is not necessarily maximal. It depends on muscle contraction velocity. The increase, lower than expected, in metabolic response from 0.5V _opt to V _opt suggests also that mechanical efficiency is higher at V _opt. Electronic Publication     

Cadence and performance in elite cyclists

Many studies have attempted to describe the optimal cadence in cycling. However, the effect on performance has received little attention. The aim of the present study was therefore to examine the effect of cadence on performance during prolonged cycling (~30 min). Fourteen male elite cyclists performed two or five time trials at different cadences [60, 80, 100, 120 rpm or freely chosen cadence (FCC)]. The total work was the same between the time trials, and the subjects were instructed to complete each time trial as fast as possible by adjusting the workload with buttons mounted on the handlebar. Accumulated work and cadence was visualised on a monitor. Oxygen uptake was measured continuously and blood lactate concentration every fifth minute. Compared to 80 rpm, finishing times at 60, 100 and 120 rpm were 3.5, 1.7 and 10.2% slower (P<0.05). Finishing time at FCC (mean 90 rpm) was indistinguishable from 80 and 100 rpm. Gross efficiency at 80 rpm was 2.9, 2.3, 3.4 and 12.3% larger than at 60, FCC, 100 and 120 rpm, respectively (P<0.05). The maximal energy turnover rate was 1.7% higher at 100 than at 80 rpm (P<0.05). This could not, however, compensate for the 3.4% lower efficiency at 100 rpm. This study demonstrated that elite cyclists perform best at their most efficient cadence despite the maximal energy turnover rate being larger at a higher cadence.     

Optimal pedalling velocity characteristics during maximal and submaximal cycling in humans

The aim of this study was to compare optimal pedalling velocities during maximal (OVM) and submaximal (OVSM) cycling in human, subjects with different training backgrounds. A group of 22 subjects [6 explosive (EX), 6 endurance (EN) and 10 non-specialised subjects] sprint cycled on a friction-loaded ergometer four maximal sprints lasting 6?s each followed by five 3-min periods of steady-state cycling at 150?W with pedalling frequencies varying from 40 to 120?rpm. The OVM and OVSM were defined as the velocities corresponding to the maximal power production and the lowest oxygen consumption, respectively. A significant linear relationship (r ² ?=?0.52, P?P?P?P?相似文献   

Effect of pedal cadence on the accumulated oxygen deficit, maximal aerobic power and blood lactate transition thresholds of high-performance junior endurance cyclists

In this study we investigated the effect of pedal cadence on the cycling economy, accumulated oxygen deficit (AOD), maximal oxygen consumption (V˙O_2max) and blood lactate transition thresholds of ten high-performance junior endurance cyclists [mean (SD): 17.4 (0.4) years; 183.8?(3.5)?cm, 71.56?(3.75)?kg]. Cycling economy was measured on three ergometers with the specific cadence requirements of: 90–100?rpm for the road dual chain ring (RDCR_90–100rpm) ergometer, 120–130?rpm for the track dual chain ring (TDCR_120–130rpm) ergometer, and 90–130?rpm for the track single chain ring (TSCR_90–130rpm) ergometer. AODs were then estimated using the regression of oxygen consumption (V˙O₂) on power output for each of these ergometers, in conjunction with the data from a 2-min supramaximal paced effort on the TSCR_90–130rpm ergometer. A regression of V˙O₂ on power output for each ergometer resulted in significant differences (P<0.001) between the slopes and intercepts that produced a lower AOD for the RDCR_90–100rpm [2.79 (0.43)?l] compared with those for the TDCR_120–130rpm [4.11?(0.78)?l] and TSCR_90–130rpm [4.06 (0.84)?l]. While there were no statistically significant V˙O_2max differences (P?=?0.153) between the three treatments [RDCR_90–100rpm: 5.31?(0.24)?l?·?min^?1; TDCR_120–130rpm; 5.33?(0.25)?l?·?min^?1; TSCR_90–130rpm: 5.44?(0.27)?l?·?min^?1], all pairwise comparisons of the power output at which V˙O_2max occurred were significantly different (P?90–100rpm and TDCR_120–130rpm tests for power output (P?=?0.003) and blood lactate (P?=?0.003) at the lactate threshold (Th_la?), and for power output (P?=?0.005) at the individual anaerobic threshold (Th_iat). Our findings emphasise that pedal cadence specificity is essential when assessing the cycling economy, AOD and blood lactate transition thresholds of high-performance junior endurance cyclists.     

Torque-velocity relationship during cycle ergometer sprints with and without toe clips

The torque-velocity relationship in cycling has been studied during all-out sprints (n?=?6 subjects) with and without toe clips on an electronic Lode ergometer with strain gauges, to estimate the importance of the expected decrease in torque, velocity and power output. As previously found with different cycling protocols, the torque-velocity relationship was linear for all-out sprints with toe clips. A similar relationship was observed when cycling without toe clips but the torque-velocity relationship was inflected downwards at low or high velocities in several subjects who were not regular cyclists. The pulling action during the rise of the pedal at low velocities cannot explain why the torque-velocity relationship is not hyperbolic for cycling exercises with toe clips because similar relationships were observed without toe clips. The maximal power output was significantly higher during cycling with toe clips (782?W vs 668?W, P?T ₀ (138 N?·?m vs 122 N?·?m, P<0.05). In contrast, the maximal extrapolated velocity, V ₀ and peak velocity were not significantly improved by the use of toe clips. The comparison of the angle-torque patterns at low and high velocities suggested that the kinetic energy of the legs can be transformed into power output when cycling without toe clips as well as it can when cycling with toe clips.     

Effect of exercise duration on optimal pedaling rate choice in triathletes.

The purpose of this study was to investigate the effect of an exercise duration similar to triathlon's cyclism event (approximately 1 hr), on factors determining the freely chosen cadence. Nine trained triathletes completed a cycling track session conducted at a speed corresponding to 75% of maximal heart rate. This session was composed of five submaximal rides performed at five cadences presented in a random order (65, 80, 95, 110 rpm and freely chosen cadence) realized before and after a 1-hr exercise at the freely chosen cadence. Results show, during the first condition, that triathletes choose spontaneously a cadence (90,1 +/- 10,7 rpm) close to the neuromuscular optimum (89,6 +/- 1,1 rpm) while at the end of exercise, a decrease of the freely chosen cadence (82,8 +/- 8,7 rpm) was observed toward the energetically optimal cadence (78,6 +/- 5,8 rpm). These findings suggest the hypothesis of an adaptation of the movement pattern with the exercise duration in order to minimize the energy cost rather than the neuromuscular cost of cycling.     

Effect of end-point cadence on the maximal work-time relationship

This study examined the effect of end-point cadence on the parameters of the work-time relationship determined for cycle ergometry. Eight male subjects completed four maximal tests on an electrically-braked cycle ergometer that regulated a constant power output independent of cadence. The power outputs imposed ranged between an average of 259 W and 403 W, whereas the corresponding durations ranged between 139 s and 1691 s. During each test subjects were required to maintain a cadence of 80–90 rpm. Accumulated time to end-point cadences of 70, 60 and 50 rpm were recorded. The four work-time determinations for each of three end-point cadences were used to determine linear relationships between work and time, yielding both a y-intercept, which represents anaerobic work capacity, and a slope, which is termed critical power (CP), for each end-point cadence. There was a significant increase in the y-intercept as end-point cadence decreased from 70 to 60 rpm (F[1,7]=36.7, p < 0.001) or 70 to 50 rpm (F[1,7]=80.1, p < 0.001), but not from 60 rpm to 50 rpm (F[1,7]=3.28, p > 0.05). In contrast, there was no effect of end-point cadence on CP (F[2,14]=1.89, p < 0.05). These results demonstrate that the end-point cadence selected to terminate tests only affects the y-intercept of the work-time relationship. To control for this effect, the cadence at which each test is terminated should be standardised if determination of anaerobic work capacity, as represented by the y-intercept, is required.     

Effects of crank length on maximal cycling power and optimal pedaling rate of boys aged 8–11 years

It is generally reported that cycle crank length affects maximal cycling power of adults and that optimal crank length is related to leg length. This suggests that the use of standard length cycle cranks may provide non-optimal test conditions for children. The purpose of this study was to determine the effects of cycle-crank length on maximal cycling power and optimal pedaling rate of 17 boys aged 8–11 years. The boys performed maximal cycle ergometry with standard (170 mm) cycle cranks and with a crank length that was 20% of estimated leg length (LL20). Power produced when using the 170 mm cranks [mean (SEM)] [364 (18) W] did not differ from that produced with the LL20 cranks [366 (19)]. Optimal pedaling rate was significantly greater for the LL20 cranks [129 (4) rpm] than for the 170 mm cranks [114 (4) rpm]. These data suggest that standard 170 mm cranks do not compromise maximal power measurements in boys aged 8–11 years so that the test apparatus does not bias physiological or developmental inferences made from tests of maximal cycling power. Electronic Publication     

The energetically optimal cadence decreases after prolonged cycling exercise

This study investigated the change in the energetically optimal cadence after prolonged cycling. The energetically optimal cadence (EOC) was determined in 14 experienced cyclists by pulmonary gas exchange at six different cadences (100–50 rpm at 10 rpm intervals). The determination of the EOC was repeated after a prolonged cycling exercise of 55 min duration, where cadence was fixed either at high (>95 rpm) or low (<55 rpm) pedalling rates. The EOC decreased after prolonged cycling exercise at a high as well as at a low fixed cadence (P < 0.01). According to the generalized muscle equations of Hill, this indicates that most likely more type I muscle fibres contribute to muscular power output after fatiguing cycling exercise compared to cycling in the beginning of an exercise bout. We suggest that the determination of EOC might be a potential non-invasive method to detect the qualitative changes in activated muscle fibres, which needs further investigation.     

Factors associated with the selection of the freely chosen cadence in non-cyclists

The purpose of this study was to examine both the freely chosen cadence (FCC) and the physical variables associated with cadence selection in non-cyclists. Eighteen participants pedalled at 40, 50, and 60% of their maximal power output (determined by a maximal oxygen uptake test, W _max), whilst cadence (50, 65, 80, 95, 110 rpm, and FCC) was manipulated. Gross efficiency, was used to analyse the most economical cadence whilst central and peripheral ratings of perceived exertion (RPE) were used to measure the most comfortable cadence and the cadence whereby muscle strain was minimised. Peak (T _peak), mean crank torque (T _mean) and the crank torque profile were analysed at 150 and 200 W at cadences of 50, 65, 80, 95, and 110 rpm in order to determine the mechanical load. FCC was found to be approximately 80 rpm at all workloads and was significantly higher than the most economical cadence (50 rpm). At 60% W _max, RPE peripheral was minimised at 80 rpm which coincided with the FCC. Both T _peak and T _mean decreased as cadence increased and, conversely, increased as power output increased. An analysis of the crank torque profile showed that the crank angle at both the top (DP_top) and the bottom (DP_bot) dead point of the crank cycle at 80 rpm occurred later in the cycling revolution when compared to 50 rpm. The findings suggested that the FCC in non-cyclists was more closely related to variables that minimise muscle strain and mechanical load than those associated with minimising metabolic economy.     

Chronic β-blockade does not influence muscle power output during high-intensity exercise of short-duration

Summary Patients receiving -receptor antagonists for the treatment of hypertension frequently complain of impaired exercise tolerance. To determine whether these medications impair skeletal muscle contractile function, we measured isokinetic muscle function in ten healthy male cyclists receiving nebivolol (N), atenolol (A), propranolol (P) and the calcium channel antagonist diltiazem (D). The subjects performed standardized tests of muscle power on an isokinetic cycle ergometer following subacute ingestion of N, A, P, D and placebo (PL) in a double blind crossover trial. Subjects exercised maximally for 10 s at 90, 110, 120, 130 and 150 rpm with 2-min rest between sessions. Thereafter, they performed a 30-s fatigue test at 120 rpm. Resting heart rate was decreased 13.4%, 21.9% and 14.6% by N, A and P, respectively (P<0.05 vs PL). Resting systolic blood pressure was decreased 6.7% by A only (P < 0.05 vs PL). Peak power, average power and work done was not different among treatment groups at any crank velocity, nor was there any difference in total work done or rate of work decline in the 30-s test. We concluded from our study that peak isokinetic muscle power during maximal exercise of short duration is not affected by -blockade or the calcium antagonist diltiazem. Fatigue during -receptor antagonism would not appear therefore to be due to changes in the ability of skeletal muscle to produce peak power output during exercise of short duration.     

Interactions between cadence and power output effects on mechanical efficiency during sub maximal cycling exercises

The purpose of this study was to investigate the interactions between cadence and power output effects on cycling efficiency. Fourteen healthy subjects performed four constant power output-tests (40, 80, 120 and 160 W) in which the cadence varied in five bouts from 40 to 120 rpm. Gross efficiency (GE) was determined over the last ten respiratory cycles of each bout and was calculated as the ratio of mechanical energy to energy expenditure. Results showed that (1) GE-cadence relationships reached a maximum at each power output corresponding to the cadence maximising efficiency (CA_eff) and (2) GE increased with power output whatever the cadence until a maximal theoretical value. Moreover, interactions were found between these two factors: the cadence effect decreased linearly with power output and the power output effect increased exponentially with cadence. Consequently, cycling efficiency decreased more when cadence differed from CA_eff at low than at high power output, and increased more with power output at high cadence than at low cadence. These interactions between cadence and power output effects on GE were mainly due to cadence and power output effects on the energy expenditure shares not contributing to power production.An erratum to this article can be found at     

A short training programme for the rapid improvement of both aerobic and anaerobic metabolism

The aim of this study was to evaluate the changes in aerobic and anaerobic metabolism produced by a newly devised short training programme. Five young male volunteers trained daily for 2 weeks on a cycle ergometer. Sessions consisted of 15-s all-out repetitions with 45-s rest periods, plus 30-s all-out repetitions with 12-min rest periods. The number of repetitions was gradually increased up to a maximum of seven. Biopsy samples of the vastus lateralis muscle were taken before and after training. Performance changes were evaluated by two tests, a 30-s all-out test and a maximal progressive test. Significant increases in phosphocreatine (31%) and glycogen (32%) were found at the end of training. In addition, a significant increase was observed in the muscle activity of creatine kinase (44%), phosphofructokinase (106%), lactate dehydrogenase (45%), 3-hydroxy-acyl-CoA dehydrogenase (60%) and citrate synthase (38%). After training, performance of the 30-s all-out test did not increase significantly, while in the maximal progressive test, the maximum oxygen consumption increased from mean (SD) 57.3 (2.6) ml · min⁻¹ · kg⁻¹ to 63.8 (3.0) ml · min⁻¹ · kg⁻¹, and the maximum load from 300 (11) W to 330 (21) W; all changes were significant. In conclusion, this new protocol, which utilises short durations, high loads and long recovery periods, seems to be an effective programme for improving the enzymatic activities of the energetic pathways in a short period of time. Accepted: 30 March 2000     

Phosphocreatine and ATP content in human single muscle fibres before and after maximum dynamic exercise

The recovery of high-energy phosphate levels in single human skeletal muscle fibres following short-term maximal (all-out) exercise was investigated. Three male volunteers exercised maximally for 25 s on an isokinetic cycling ergometer. Muscle biopsy samples from the vastus lateralis were collected at rest, immediately post-exercise and at 1.5 min of recovery. The subjects also performed a second exercise bout 1.5 min after the first, on a separate occasion. Single muscle fibres were dissected, characterized and assigned to one of four groups according to their myosin heavy chain (MyHC) isoform content; namely, type I, IIA, IIAx and IIXa (the latter two groups containing either less or more than 50% IIX MyHC). Fibres were analysed for adenosine 5'-triphosphate (ATP), inosine-5'-monophosphate (IMP), phosphocreatine (PCr) and creatine (Cr) levels. Type I fibres had a lower Cr content than type II fibres (P<0.01). Within type II fibres resting [PCr] increased with increasing MyHC IIX isoform content (r=0.59, P<0.01). Post-exercise [PCr] was very low in all fibre groups (P<0.01 versus rest) while great reductions in ATP were also observed (P<0.01 versus rest), especially in the type II fibre groups. [PCr] at 1.5 min of recovery was still lower compared to rest for all fibre groups (P<0.01) especially in the IIAx and IIXa fibres.     

Oxygen deficits incurred during 45, 60, 75 and 90-s maximal cycling on an air-braked ergometer

Summary The aims of this study were to determine the most appropriate duration for the measurement of the maximal accumulated O₂ deficit (MAOD), which is analogous to the anaerobic capacity, to ascertain the effects of mass, fat free mass (FFM), leg volume (V _leg) and lower body volume (V _1b) on anaerobic test performance, to examine the reproducibility for peak power output ( ) or maximal anaerobic power using an air-braked cycle ergometer and to produce approximations for the percentages of aerobic and anaerobic metabolism during exercise of short duration but high intensity. A group of 12 endurance trained cyclists [mean age 25.1 (SD 4.6) years; mean body mass 73.43 (SD 7.12) kg; mean maximal oxygen consumption 5.12 (SD 0.35) l·min^–1; mean body fat 12.5 (SD 4.1) %] accordingly performed four counterbalanced treatments of 45, 60, 75 and 90 s of maximal cycling on an air-braked ergometer. The mean O₂ deficit of 3.52 l for the 45-s treatment was significantly less (P < 0.01) than those for the 60 (3.75 l), 75 (3.80 l) and 90-s (3.75 l) treatments. These data therefore indicate that in predominantly aerobically trained subjects the O₂ deficit attains a plateau after 60 s of maximal cycling on an air-braked ergometer. Statistically significant interclass correlation coefficients (P<0.05) between the anthropometric variables (mass, FFM, V _leg and V_1b) and or maximal anaerobic power (0.624–0.748) and MAOD (ml) or anaerobic capacity (0.666–0.772) furthermore would suggest the relevance of taking into account muscle mass during anaerobic tests. Intraclass correlation coefficients (0.935–0.946; all P<0.001) would indicate a high degree of reliability for the measurement of . The relative importance of anaerobic work decreased from 60% for the 45-s test to 40% for the 90-s one. Hence our study showed that both aerobic and anaerobic metabolism contributed significantly during all-out tests of 45–90 s duration.     

Relationship between gear ratio and 10-s sprint cycling on an air-braked ergometer

This investigation examined the relationship between gear ratio and peak and mean power outputs (PPO and MPO) and peak cadence (PC) during a 10-s all-out sprint on a multi-geared air-braked cycle ergometer. Ten physically active men [mean age 21.0 years (SEM 0.7)] performed in random order six 10-s sprints (15-min rest between each sprint) on two occasions (48 h apart) in six different gear ratios; flywheel revolutions per pedal crank revolution (FR/PCR) ranged between 5.22 and 11.61. The PPO, MPO, and PC were recorded from each sprint. Of the six gear ratios tested, a gear ratio eliciting 8.87 FR/PCR elicited the highest PPO for the initial test session; the PPO output of 1274 W was significantly greater (P < 0.01) than that produced in the other five gears. Analysis of data from the second test session revealed no statistically significant difference in PPO between gear ratios eliciting 8.00, 8.87, and 10.06 FR/PCR. The PPO from these three ratios were significantly greater (P > 0.05) than those produced using the ratios resulting in 6.32, 7.06, and 10.78 FR/PCR. The PC in the gear ratio maximising PPO was 120 rpm. Analysis of PC data revealed a significant decrease (P < 0.05) as the number of FR/PCR increased.     

The most economical cadence increases with increasing workload

Several studies have suggested that the most economical cadence in cycling increases with increasing workload. However, none of these studies have been able to demonstrate this relationship with experimental data. The purpose of this study was to test the hypothesis that the most economical cadence in elite cyclists increases with increasing workload and to explore the effect of cadence on performance. Six elite road cyclists performed submaximal and maximal tests at four different cadences (60, 80, 100 and 120 rpm) on separate days. Respiratory data was measured at 0, 50, 125, 200, 275 and 350 W during the submaximal test and at the end of the maximal test. The maximal test was carried out as an incremental test, conducted to reveal differences in maximal oxygen uptake and time to exhaustion (short-term performance) between cadences. The results showed that the lowest oxygen uptake, i.e. the best work economy, shifted from 60 rpm at 0 W to 80 rpm at 350 W (P<0.05). No difference was found in maximal oxygen uptake among cadences (P>0.05), while the best performance was attained at the same cadence that elicited the best work economy (80 rpm) at 350 W (P<0.05). This study demonstrated that the most economical cadence increases with increasing workload in elite cyclists. It was further shown that work economy and performance are related during short efforts (~5 min) over a wide range of cadences.     

Constant external work cycle exercise – the performance and metabolic effects of all-out and even-paced strategies

The purpose of the present study was to establish whether the performance of an all-out sprint could be replicated and the metabolic responses moderated in two further trials involving pre-set constant average pedalling rates. A total of 24 subjects (12 males and 12 females) completed a 30-s high-speed maximal all-out effort on a cycle ergometer against an applied resistance equal to 7.5% of their body mass. On two further occasions the applied resistance was increased so that the external work of the all-out effort could be replicated by adopting a pre-determined constant average pedal rate. When the required pedal rate was within the range of 60–90 rev??·??min^?1 the subjects were able to maintain the rate for the full 30-s and so could replicate the external work of the all-out effort. They were unable to sustain a faster constant rate within the range of 97–150 rev??·??min^?1 for the full 30 s, resulting in ≈7% less external work being achieved (P?P?P?相似文献