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Music is widely used as an ergogenic aid in sport, but there is little evidence of its effectiveness during closedloop athletic events. In order to determine the effectiveness of music as an ergogenic aid, well-trained and task-habituated cyclists performed 10-km cycle time trials either while listening to self-selected motivational music or with auditory input blocked. There were no statistically significant differences in performance time or physiological or psychological markers related to music (time-trial duration 17.75 ± 2.10 vs 17.81 ± 2.06 min, mean power output 222 ± 66 vs 220 ± 65 W, peak heart rate 184 ± 9 vs 183 ± 8 beats/min, peak blood lactate 12.1 ± 2.6 vs 11.9 ± 2.1 mmol/L, and final rating of perceived exertion 8.4 ± 1.5 vs 8.5 ± 1.6). It is concluded that during exercise at competitive intensity, there is no meaningful effect of music on either performance or physiology.

Aerobic exercise performance is seriously compromised in the heat. Possibly, a high skin temperature causes a rating of perceived exertion (RPE)-mediated decrease in exercise intensity. The purpose of this study was to determine the effect of skin temperature on power output during a 7.5-km cycling time trial. Thirteen well-trained male subjects performed a 7.5-km cycling time trial at 15°C and 50% relative humidity (CONTROL), with radiative heat stress during the time trial, and with (PRECOOL) or without (HEAT) precooling. Heat stress was applied by infrared heaters positioned in front of the cycle ergometer between 1.5 and 6.0 km. Skin, rectal, and pill temperature, power output, heart rate, and RPE were measured during the trial. Despite the lower mean skin temperature at the start of the time trial for PRECOOL compared to HEAT (-2.1 ± 0.7°C; P < 0.01) and CONTROL (-1.8 ± 0.6°C; P < 0.05), and a greater increase in mean skin temperature during the heat stress period for PRECOOL (4.5 ± 1.0°C) and HEAT (3.9 ± 0.8°C) than for CONTROL (-0.3 ± 0.6°C; P < 0.01), no differences in power output were found between HEAT (273 ± 45 W) and CONTROL (284 ± 43 W; P = 0.11) and between HEAT and PRECOOL (266 ± 50 W; P = 0.47). Power output during the time trial was greater for CONTROL than for PRECOOL (P < 0.05). Additionally, no differences were observed in core temperature measures, HR, and RPE. Skin temperature does not affect the selection and modulation of exercise intensity in a 7.5-km cycling time trial. © 2012 The Author(s).

Background: Athletic competition has been a source of interest to the scientific community for many years, as a surrogate of the limits of human ambulatory ability. One of the remarkable things about athletic competition is the observation that some athletes suddenly reduce their pace in the mid-portion of the race and drop back from their competitors. Alternatively, other athletes will perform great accelerations in mid-race (surges) or during the closing stages of the race (the endspurt). This observation fits well with recent evidence that muscular power output is regulated in an anticipatory way, designed to prevent unreasonably large homeostatic disturbances. Principal Findings: Here we demonstrate that a simple index, the product of the momentary Rating of Perceived Exertion (RPE) and the fraction of race distance remaining, the Hazard Score, defines the likelihood that athletes will change their velocity during simulated competitions; and may effectively represent the language used to allow anticipatory regulation of muscle power output. Conclusions: These data support the concept that the muscular power output during high intensity exercise performance is actively regulated in an anticipatory manner that accounts for both the momentary sensations the athlete is experiencing as well as the relative amount of a competition to be completed. © 2011 de Koning et al.

Before the influence of divergent factors on gross efficiency (GE) [the ratio of mechanical power output (PO) to metabolic power input (PI)] can be assessed, the variation in GE between days, i.e. the test-retest reliability, and the within day variation needs to be known. Physically active males (n = 18) performed a maximal incremental exercise test to obtain VO2max and PO at VO2max (PVO2max), and three experimental testing days, consisting of seven submaximal exercise bouts evenly distributed over the 24 h of the day. Each submaximal exercise bout consisted of six min cycling at 45, 55 and 65% PVO2max, during which VO(2) and RER were measured. GE was determined from the final 3 min of each exercise intensity with: GE = (PO/PI) x 100%. PI was calculated by multiplying VO2 with the oxygen equivalent. GE measured during the individually highest exercise intensity with RER1.0 did not differ significantly between days (F = 2.70, p = 0.08), which resulted in lower and upper boundaries of the 95% limits of agreement of 19.6 and 20.8%, respectively, around a mean GE of 20.2%. Although there were minor within day variations in GE, differences in GE over the day were not significant (F = 0.16, p = 0.99). The measurement of GE during cycling at intensities approximating VT is apparently very robust, a change in GE of approximately 0.6% can be reliably detected. Lastly, GE does not display a circadian rhythm so long as the criteria of a steady-state VO(2) and RER1.0 are applied.

In rowing, power is inevitably lost as kinetic energy is imparted to the water during push-off with the blades. Power loss is estimated from reconstructed blade kinetics and kinematics. Traditionally, it is assumed that the oar is completely rigid and that force acts strictly perpendicular to the blade. The aim of the present study was to evaluate how reconstructed blade kinematics, kinetics, and average power loss are affected by these assumptions. A calibration experiment with instrumented oars and oarlocks was performed to establish relations between measured signals and oar deformation and blade force. Next, an on-water experiment was performed with a single female world-class rower rowing at constant racing pace in an instrumented scull. Blade kinematics, kinetics, and power loss under different assumptions (rigid versus deformable oars; absence or presence of a blade force component parallel to the oar) were reconstructed. Estimated power losses at the blades are 18% higher when parallel blade force is incorporated. Incorporating oar deformation affects reconstructed blade kinematics and instantaneous power loss, but has no effect on estimation of power losses at the blades. Assumptions on oar deformation and blade force direction have implications for the reconstructed blade kinetics and kinematics. Neglecting parallel blade forces leads to a substantial underestimation of power losses at the blades. © 2010 Taylor & Francis.

Purpose. To demonstrate the applicability of the power balance model to elite handcycling and to obtain values for gross efficiency (GE).Methods. Four members of the Dutch Paralympic team performed trials on a 250-m indoor track. Velocity (v) and power output (PO) were measured in conjunction with physiological measures to obtain values for GE. The data were used to construct and validate a power balance model of handcycling.Results. The empirically derived relationship between PO and velocity was: PO = 0.20v3 + 2.90v (R2 = 0.95). Mean GE during submaximal performance was 17.9% ± 1.6%.Conclusion. Handcycling performance can successfully be modelled with a power balance model. The model provides insight into the magnitude of power production and dissipation during elite handcycling. Handcycling is a relatively efficient upper body mode of propulsion with associated high metabolic demand at race velocities.

The quality of performance during international competitions such as the Olympic Games and various world championships is often judged by the number of world records attained. The simple fact that world records continue to improve is evidence that sports performance is progressing. Does this also mean that athletes are improving? Is the continual progression of world-record performances evidence that contemporary athletes are superior to the athletes who performed in the past? Technological developments may obscure insight into the athletic enhancement made by athletes over the years. This commentary tries to separate technological and athletic enhancement in the progression of world records by the use of a power balance model.

An analysis of the start of the 500 m speed skating races during the 1988 Olympic Winter Games showed a remarkably high correlation between the acceleration of the skater in the first second of the sprint and the final time (r = -0.75). In this study a power equation is used to explain this high coefficient of correlation. The performance in speed skating is determined by the capability of external power production by the speed skater. This power is necessary to overcome the air and ice friction and to increase the kinetic energy of the skater. Numerical values of the power dissipated to air and ice friction, both dependent on speed, are obtained from ice friction and wind tunnel experiments. Using aerobic and anaerobic power production as measured during supra maximal bicycle tests of international-level speed skaters, a model of the kinetics of power production is obtained. Simulation of power production and power dissipation yields values of speed and acceleration and, finally, the performance time of the sprint during speed skating. The mean split time at 100 m and the final time at 500 m in these races, derived from simulation, were 10.57 s (+/- 0.31) and 37.82 s (+/- 0.96), respectively. The coefficient of correlation between the simulated 500 m times and the actual 500 m times was 0.90. From the results of this study it can be concluded that the distribution of the available anaerobic energy is an important factor in the short lasting events. For the same amount of anaerobic energy the better sprinters appear to be able to liberate considerably more energy at the onset of the race than skaters of lower performance level.

During speed skating, the external power output delivered by the athlete is predominantly used to overcome the air and ice frictional forces. Special skates were developed and used to measure the ice frictional forces during actual speed skating. The mean coefficients of friction for the straights and curves were, respectively, 0.0046 and 0.0059. The minimum value of the coefficient of ice friction was measured at an ice surface temperature of about −7°C. It was found that the coefficient of friction increases with increasing speed. In the literature, it is suggested that the relatively low friction in skating results from a thin film of liquid water on the ice surface. Theories about the presence of water between the rubbing surfaces are focused on the formation of water by pressure-melting, melting due to frictional heating and on the ‘liquid-like’ properties of the ice surface. From our measurements and calculations, it is concluded that the liquid-like surface properties of ice seem to be a reasonable explanation for the low friction during speed skating.

The ability to modify power output (PO) in response to a changing stimulus during exercise is crucial for optimizing performance involving an integration system involving a performance template and feedback from peripheral receptors. The rapidity with which PO is modified has not been established, but would be of interest relative to understanding how PO is regulated. The objective is to determine the rapidity of changes in PO in response to a hypoxic challenge, and if change in PO is linked to changes in arterial O2 saturation (S aO2). Well-trained cyclists performed randomly ordered 5-km time trials. Subjects began the trials breathing room air and switched to hypoxic (HYPOXIC, FIO2 = 0.15) or room (CONTROL, FIO2 = 0.21) air at 2 km, then to room air at 4 km. The time delay to begin decreasing S aO2 and PO and to recover S aO2 and PO on to room air was compared, along with the half time (t 1/2) during the HYPOXIC trial. Mean S aO2 and PO between 2 and 4 km were significantly different between CONTROL and HYPOXIC (94 ± 2 vs. 83 ± 2% and 285 ± 16 vs. 245 ± 19 W, respectively). There was no difference between the time delay for S aO2 (31.5 ± 12.8 s) and in PO (25.8 ± 14.4 s) or the recovery of S aO2 (29.0 ± 7.7 s) and PO (21.5 ± 12.4 s). The half time for decreases in S aO2 (56.6 ± 14.4 s) and in PO (62.7 ± 20.8 s) was not significantly different. Modifications of PO due to the abrupt administration of hypoxic air are related to the development of arterial hypoxemia, and begin within ~30 s.

It has been suggested that the optimal stroke rate in rowing is partly determined by the stroke-rate dependence of internal power losses. This should be reflected in a stroke-rate dependency of gross efficiency (e(gross)). The purpose of this study was to investigate if e(gross) is affected by stroke rate. A second aim was to determine whether internal power losses can be estimated by the negative power output during the stroke cycle (P(negative)).Seventeen well-trained female rowers participated in this study. They rowed three trials on a modified rowing ergometer on slides at a submaximal intensity, with a respiratory exchange ratio of 1 or close to 1. Stroke rates were 28, 34, and 40 strokes per minute. The trials were fully randomized. Power transfer to the flywheel was kept constant whereas e(gross) was determined during each trial.No significant differences in e(gross) were found between conditions. This finding suggests that in rowing internal power losses are not influenced by stroke rate. Furthermore, although P(negative) increased at increasing stroke rate (P0.001), no relationship was found with e(gross). This suggests that P(negative) is not a reliable measure to estimate internal power losses.This study shows that within the range of stroke rates applied in competitive rowing, internal power losses are unrelated to rowing cycle frequency.

Limited research has been done on the .VO2 response to time trial exercise in the supramaximal domain or during free range exercise typical of competition. The present study was designed to measure and to model the .VO2 response during supramaximal time trial exercise.Well-trained cyclists (n = 9) performed a 1-min incremental exercise test to obtain maximal power output (P (.VO2max)) and four cycle ergometer time trials of different distances (750, 1500, 2500, and 4000 m). Athletes were instructed to finish in as little time as possible. .VO2 was measured breath-by-breath and modeled monoexponentially over the first 54 s (750 m) or 114 s (1500, 2500, and 4000 m) of the time trials.Mean P (.VO2max) in the incremental test was 383 +/- 28 W. Mean .VO(2max) was 4.5 +/- 0.2 L.min(-1). All time trials were characterized by an initial burst in power output during the first 15 s (175 +/- 23%, 149 +/- 14%, 145 +/- 14%, 139 +/- 10% P (.VO2max) being largest for 750 m. Simultaneously, the mean response time was significantly smaller in 750 m compared with all other trials (18.8 +/- 2.2, 20.9 +/- 1.9, 20.8 +/- 1.5, and 21.2 +/- 2.2 s).Near maximal values of .VO2 can be reached within 2 min of strenuous exercise. The larger initial burst in power output in 750 m was accompanied by a faster .VO2 response and seems to be of importance to trigger the aerobic system maximally.

The purpose of this study was to describe the intermuscular coordination and power production for the constrained asymmetrical movement during skating the curves. Seven elite male speed skaters took part in the experiments. The speed skaters were simultaneously filmed from frontal and sagittal views. EMGs were obtained telemetrically and push-off force was registered with special skates. Inverse dynamic analysis yielded power production data, which differed for left and right leg. Marked differences were also found in intermuscular coordination of each leg. The activation patterns of the muscles were influenced by the asymmetrical nature and the typical body position during the speed skating movement. External power output was determined by three methods. The mean joint power output for left and right leg showed similar values as the external power output calculated from air and ice friction. These values were lower than the values predicted with a geometrical model for skating the curves.

Five speed skaters of elite performance level and six speed skaters of trained level were subjected to an inverse dynamical analysis during speed skating. Push-off forces were registered by means of special skates. Myoelectric activity (EMG) of ten leg muscles and cinematographic data were recorded. Linked segment modelling yielded net joint moments and joint powers. The speed skating technique is characterized by a typical horizontal position of the trunk and a suppression of a plantar flexion during the push-off. This technique, necessary to reduce external friction, constrains the transfer of rotation in joints to translation of the mass center of the body. In spite of constrained push-off, the EMG levels of the leg muscles show a proximo-distal temporal order which to a certain extent is comparable to that previously found in an unconstrained vertical jump. This proximo-distal sequence is also reflected by the time courses of the net moment and net power output in hip, knee and ankle joints. The temporal sequence in activation levels of activated muscles is not different between elite and trained speed skaters. The difference in performance level between these groups obviously has an origin in the ability of the elite speed skaters to realise larger net joint moments. Differences in net joint moments and in kinematics result in a higher power output and a lower air frictional force for the elite than for the trained speed skaters.

Purpose: In rowing, the athlete has to maximize power output and to minimize energy losses to processes unrelated to average shell velocity. The contribution of velocity efficiency (evelocity; the fraction of mechanical power not lost to velocity fluctuations) to rowing performance in relation to the contributions of maximum oxygen uptake (V[spacing dot above]O2max) and gross efficiency (egross) was investigated. Relationships between evelocity and movement execution were determined. Methods: Twenty-two well-trained female rowers participated in two testing sessions. In the first session, they performed a 2000-m time trial on a modified rowing ergometer that allowed for power losses due to velocity fluctuations. The V[spacing dot above]O2max, the evelocity, and the amount of rower-induced impulse fluctuations (RIIF) due to horizontal handle and foot stretcher forces were determined in a steady state part of the time trial. RIIF was used as a measure of movement execution. In the second session, egross was determined at submaximal intensity. Results: As expected, V[spacing dot above]O2max accounted for the major part of explained variance in the 2000-m time (53%, P < 0.001). Velocity efficiency accounted for a further 14%, egross for 11% (P < 0.05). Negative correlations were found between evelocity and RIIF values of several discreet intervals within a stroke cycle. The results suggest that optimal timing of forces applied to the ergometer will help minimizing power loss to velocity fluctuations. Conclusions: This study indicates that a relationship exists between performance and evelocity. Furthermore, evelocity appears to be related to movement execution, in particular the timing of handle and foot stretcher forces.

BACKGROUND: Previous studies suggest that the rating of perceived exertion (RPE) increases during steady-state, open-loop exercise in proportion to the relative time to fatigue. This suggests that RPE is scalar and integrates physiological status and homeostatic disturbances. PURPOSE: This study assessed the relationship between the rate of change in RPE, and relative distance in time trials at distances of 2.5, 5, and 10 km. It also assessed the rate of change in RPE during 5-km time trials while breathing hypoxic air. METHODS: The subjects were well-conditioned cyclists. In part 1, each subject completed habituation time trials, and then randomly ordered time trials at each distance. The category ratio RPE was measured in 10% increments throughout each trial. In part 2, each subject completed three 5-km time trials while breathing different inspired gas mixtures (FiO2 = 0.2093 throughout the trial, FiO2 = 0.15 between 2 and 4 km, and FiO2 = 0.15 between 2.5 and 4 km). RPE was measured at 10% increments. RESULTS: In part 1, when RPE was plotted against relative distance, there was no significant difference in the growth of RPE at proportional distances. In part 2, the decrease in power output during the hypoxic segments was sufficient that the growth of RPE was the same at each proportional distance. In both parts of the study, an RPE of 5 (hard) was achieved after 20% of the time trial distance, and an RPE of 8 was achieved after 80% distance. CONCLUSIONS: This study supports the hypothesis that RPE increases similarly in relation to relative distance, regardless of the distance performed, and it suggests that the perception of effort has scalar properties. ©2008The American College of Sports Medicine.

Portable equipment for active measurements of push-off force and ice friction was developed. The equipment consists of a pair of skates with three measuring elements between the shoe and the skate blade to register force in both fore/aft and normal direction. A portable computer samples the friction force and normal force signals during one or more strokes, calculates the mean coefficient of ice friction, and stores the sampled data in memory. The push-off force and ice friction force were measured. The peak push-off forces reach values of up to 140% of body weight. The magnitude of the coefficient of ice friction varies, depending on the weather conditions and preparatory method, generally between 0.003 and 0.007 when skating the straightaway. During the skating of the curves the coefficient of ice friction is 35% higher, most likely due to the different skating technique in the curves.

A critical assumption in modeling optimal pacing strategy is that the amount of anaerobic energy that can be produced during a time trial is a constant value, independent of pacing strategy. To test this assumption, the effect of manipulations of pacing strategy on anaerobic work produced during a 1500-m cycling time trial was studied. Additionally, the effect of pacing strategy on aerobic and total work was studied.Nine well-trained cyclists performed three 1500-m cycle ergometer time trials with different strategies (conservative (SUB), even paced (EVEN), and aggressive (SUPRA)). Anaerobic work, aerobic work, and total work were calculated on the basis of V O2, RER, gross efficiency, and external power output.ANOVA showed that total anaerobic work did not differ per strategy (EVEN: 27,604 +/- 1103 J, SUB: 26,495 +/- 1958 J, and SUPRA: 26,949 +/- 2062 J). No differences in aerobic work (EVEN: 28,266 +/- 1623 J,SUB: 27,950 +/- 1418 J, SUPRA: 27,844 +/- 1965 J) were evident, either. Subjects were able to accomplish significantly (P0.05) more total work during EVEN (55,870 +/- 2245 J) than during SUB and SUPRA (54,444 +/- 2306 and 54,794 +/- 2402 J, respectively).No difference in anaerobic and aerobic work was found per pacing strategy. Though relevant for sports performance, the differences in total work were relatively small (approximately 2%), considering the broad range of imposed strategies. The assumption that anaerobic work is a constant value, independent of pacing strategy, seems valid in the range of different strategies that are currently simulated in the energy flow models.

PURPOSE: To compare the historical evolution of performance for males and females in anaerobically dominated sprint events in three different sports: running, swimming, and speed skating. METHODS: Times of the top six finishers in a total of 283 men's and women's Olympic and world championship finals held between 1952 and 2006 were analyzed, and performance differences between males and females were calculated for each final position. RESULTS: After a relatively faster rate of improvement among females from the 1950s to a nadir in the 1980s, the gender difference in anaerobic performance at the highest levels of international competition has actually increased during the last 15 yr. Overall, the time-based performance difference for all six events analyzed has increased from a low of 10.3% in the period 1976-1988 to a current difference of 11.5% for the period 2000-2005. CONCLUSIONS: Analysis of elite sprinting performance in running, swimming, and speed skating during the last 50 yr reveals that the performance difference between males and females has ceased to narrow and has actually widened since the mid-1990s. The change observed cannot be explained by declining women's participation in sport, poorer training practice, or reduced access to technological developments, but it does coincide with dramatic improvements in the scope and sensitivity of drug testing. Current gender differences in performance, and the underlying differences in performance power, may now reasonably reflect the true physiological differences between males and females. ©2007The American College of Sports Medicine.

HETTINGA, F. J., J. J. DE KONING, E. MEIJER, L. TEUNISSEN, and C. FOSTER. Effect of Pacing Strategy on Energy Expenditure during a 1500-m Cycling Time Trial. Med. Sci. Sports Exerc., Vol. 39, No. 12, pp. 2212–2218, 2007. Purpose: A critical assumption in modeling optimal pacing strategy is that the amount of anaerobic energy that can be produced during a time trial is a constant value, independent of pacing strategy. To test this assumption, the effect of manipulations of pacing strategy on anaerobic work produced during a 1500-m cycling time trial was studied. Additionally, the effect of pacing strategy on aerobic and total work was studied. Methods: Nine well-trained cyclists performed three 1500-m cycle ergometer time trials with different strategies (conservative (SUB), even paced (EVEN), and aggressive (SUPRA)). Anaerobic work, aerobic work, and total work were calculated on the basis of VuO2, RER, gross efficiency, and external power output. Results: ANOVA showed that total anaerobic work did not differ per strategy (EVEN: 27,604 T 1103 J, SUB: 26,495 T 1958 J, and SUPRA: 26,949 T 2062 J). No differences in aerobic work (EVEN: 28,266 T 1623 J, SUB: 27,950 T 1418 J, SUPRA: 27,844 T 1965 J) were evident, either. Subjects were able to accomplish significantly (P G 0.05) more total work during EVEN (55,870 T 2245 J) than during SUB and SUPRA (54,444 T 2306 and 54,794 T 2402 J, respectively). Conclusion: No difference in anaerobic and aerobic work was found per pacing strategy. Though relevant for sports performance, the differences in total work were relatively small (~2%), considering the broad range of imposed strategies. The assumption that anaerobic work is a constant value, independent of pacing strategy, seems valid in the range of different strategies that are currently simulated in the energy flow models. Key Words: POWER OUTPUT, AEROBIC WORK, ANAEROBIC CAPACITY, HIGH PERFORMANCE

PURPOSE: Athletes occasionally follow pacing patterns that seem unreasonably aggressive compared with those of prerace performances, potentially because of the motivation provided by competition. This study evaluated the effect of extrinsic motivation on cyclists' time trial performance. METHODS: Well-trained recreational cyclists (N = 7) completed four 1500-m laboratory time trials including a practice trial, two self-paced trials, and a trial where a monetary reward was offered. Time, total power output, power output attributable to aerobic and anaerobic metabolic sources, V̇O2, and HR were measured. RESULTS: The time required for the second, third, and last (extrinsically motivated) time trials was 133.1 ± 2.1, 134.1 ± 3.4, and 133.6 ± 3.0 s, respectively, and was not different (P > 0.05). There were no differences for total (396 ± 19, 397 ± 23, and 401 ± 17 W), aerobic (253 ± 12, 254 ± 10, and 246 ± 13 W), and anaerobic (143 ± 14, 143 ± 21, and 155 ± 11 W) power output. The highest V̇O2 was not different over consecutive time trials (3.76 ± 0.19, 3.73 ± 0.16, and 3.71 ± 0.22 L·min). When ranked by performance, without reference to the extrinsic motivation (131.9 ± 2.4, 133.4 ± 2.4, and 135.4 ± 2.5 s), there was a significant difference for the first 100 m and from 100 to 300 m in power output, with a larger total power (560 ± 102, 491 ± 82, and 493 ± 93; and 571 ± 94, 513 ± 41, and 484 ± 88 W) and power attributable to anaerobic sources (446 ± 100, 384 ± 80, and 324 ± 43; and 381 ± 87, 383 ± 90, and 289 ± 91 W) for the fastest trial. CONCLUSION: Extrinsic motivation did not change the time trial performance, suggesting that 1500-m performance is extremely stable and not readily changeable with simple external motivation. The results suggest that spontaneous improvement in performance for time trials of this duration is attributable to greater early power output, which is primarily attributable to anaerobic metabolic sources. ©2007The American College of Sports Medicine.

Purpose: This study was designed to determine the effect of warm-up on 3-km cycling time trial (TT) performance, and the influence of accelerated V̇O2 kinetics on such effect. Methods: Eight well-trained road cyclists, habituated to 3-km time trials, performed randomly ordered 3-km TT after a) no warm-up (NWU), b) easy warm-up (EWU) (15 min comprised of 5-min segments at 70, 80, and 90% of ventilatory threshold (VT) followed by 2 min of rest), or c) hard warm-up (HWU) (15 min comprised of 5-min segments at 70, 80, and 90% VT, plus 3 min at the respiratory compensation threshold (RCT) followed by 6 min of rest). V̇O2 and power output (SRM), aerobic and anaerobic energy contributions, and V̇O2 kinetics (mean response time to 63% of the V̇O2 observed at 2 km) were determined throughout each TT. Results: Three-kilometer TT performance was (P < 0.05) improved for both EWU (266.8 ± 12.0 s) (−2.8%) and HWU (267.3 ± 10.4 s) (−2.6%) versus NWU (274.4 ± 12.1 s). The gain in performance was predominantly during the first 1000 m in both EWU (48% of gain) and HWU (53% of gain). This reflected a higher power output during the first 1000 m in both EWU (384 W) and HWU warm-up (386 W) versus NWU (344 W) trials. The mean response time was faster in both EWU (45 ± 10 s) and HWU (41 ± 12 s) versus NWU (52 ± 13 s) trials. There were no differences in anaerobic power output during the trials, but aerobic power output during the first 1000 m was larger during both EWU (203 W) and HWU (208 W) versus NWU (163 W) trials. Conclusions: During endurance events of intermediate duration (4–5 min), performance is enhanced by warm-up irrespective of warm-up intensity. The improved performance is related to an acceleration of V̇O2 kinetics. Sin financiación 2.831 JCR (2005) Q1, 4/70 Sport sciences UEM

HOUDIJK, H., M. F. BOBBERT, J. J. DE KONING, and G. DE GROOT. The Effects of Klapskate Hinge Position on Push-off Performance: A Simulation Study. Med. Sci. Sports Exerc., Vol. 35, No. 12, pp. 2077–2084, 2003. Purpose: The introduction of the klapskate in speed skating confronts skaters with the question of how to adjust the position of the hinge in order to maximize performance. The purpose of this study was to reveal the constraint that klapskate hinge position imposes on push-off performance in speed skating. Method: For this purpose, a model of the musculoskeletal system was designed to simulate a simplified, twodimensional skating push off. To capture the essence of a skating push off, this model performed a one-leg vertical jump, from a frictionless surface, while keeping its trunk horizontally. In this model, klapskate hinge position was varied by varying the length of the foot segment between 115 and 300 mm. With each foot length, an optimal control solution was found that resulted in the maximal amount of vertical kinetic and potential energy of the body’s center of mass at take off (W eff). Results: Foot length was shown to considerably affect push-off performance. Maximal Weff was obtained with a foot length of 185 mm and decreased by approximately 25% at either foot length of 115 mm and 300 mm. The reason for this decrease was that foot length affected the onset and control of foot rotation. This resulted in a distortion of the pattern of leg segment rotations and affected muscle work (W mus) and the efficacy ratio (Weff/Wmus) of the entire leg system. Conclusion: Despite its simplicity, the model very well described and explained the effects of klapskate hinge position on push off performance that have been observed in speed-skating experiments. The simplicity of the model, however, does not allow quantitative analyses of optimal klapskate hinge position for speed-skating practice. Key Words: SPEED SKATING, SPORTS EQUIPMENT, LOCOMOTION, MUSCULO-SKELETAL MODEL, BIOMECHANICS

FOSTER, C., J. J. DE KONING, F. HETTINGA, J. LAMPEN, K. L. LA CLAIR, C. DODGE, M. BOBBERT, and J. P. PORCARI. Pattern of Energy Expenditure during Simulated Competition. Med. Sci. Sports Exerc., Vol. 35, No. 5, pp. 826 – 831, 2003. Purpose: To determine how athletes spontaneously use their energetic reserves when the only instruction was to finish in minimal time, and whether experience from repeated performance changes the strategy of recreational athletes. Methods: Recreational road cyclists/speed skaters (N 9) completed three laboratory time trials of 1500 m on a windload braked cycle. The pattern of energy use was calculated from total work and from the work attributable to aerobic metabolism, which allowed computation of anaerobic energy use. Regional level speed skaters (N 8) also performed a single 1500-m time trial with the same protocol and measurements. Results: The serial trials were completed in (mean SD) 133.8 6.6, 133.9 5.8, 133.8 5.5 s( P 0.05 among trials); and in 125.7 10.9 s in the skaters (P 0.05 vs cyclists). The V u O2peak during the terminal 200 m was similar within trials (3.23 0.44, 3.34 0.44, 3.30 0.51 (P 0.05)) versus 3.91 0.68 L·min 1 in the skaters (P 0.05 vs cyclists). In all events, the initial power output and anaerobic energy use was high and decayed to a more or less constant value (~25% of peak) over the remainder of the event. Contrary to predictions based on an assumed “all out” starting strategy, the subjects reserved some of their ability to perform anaerobic work for a terminal acceleration. The total work accomplished was not different between trials (43.53, 43.78, and 47.48 kJ in the recreational athletes, or between the cyclists and skaters (47.79 kJ). The work attributable to anaerobic sources was not different between the rides (20.67, 20.53, and 21.12 kJ in the recreational athletes). In the skaters, the work attributable to anaerobic sources was significantly larger versus the cyclists (24.67 kJ). Conclusion: Energy expenditure during high-intensity cycling seems: 1) to be expended in a manner that allows the athlete to preserve an anaerobic energetic contribution throughout an event, 2) does not appear to have a large learning effect in already well trained cyclists, and 3) anaerobic energy expenditure may be the performance discriminating factor among groups of

The effects of short-term oral creatine supplementation (20 g a day for 6 days) on muscle activation, fatigue and recovery of the m. quadriceps femoris and on maximum performance sprint cycling were investigated during electrical stimulation. Twenty-three well-trained rowers participated in this double blind, placebo-controlled study. Forty repetitive electrically stimulated concentric contractions were imposed at a constant angular velocity of 180°/s (from 90°-140° knee angle). To determine recovery, torque was measured at various intervals after the last contraction. In addition, two maximum 30 second sprints were performed on a cycle ergometer (4 minutes rest). Body mass (mean ± SEM) increased significantly from 85.7± 2.7 to 87.3 ± 2.9 kg in the creatine group (placebo group: 82.6 ± 3.0 to 82.7 ± 2.9 kg). Creatine supplementation had no effect on maximal voluntary isometric torque or on electrically-elicited torque production, fatigability or the recovery rate. Furthermore, there were no significant effects on peak power, time to peak power and work to peak power, or on total work during the two sprints. It was concluded that short-term oral creatine supplementation does not enhance muscle performance or maximum output during sprint cycling.

The present study investigates which physiological sources support the increase in mechanical power output (W out) that can be obtained using klapskates in speed skating. It was hypothesized that the increase in W out could be achieved through an increase in gross efficiency or an increase in aerobic power (W aer). Six speed skaters performed a submaximal and maximal 1,600-m skating test with both klapskates and conventional skates, to measure gross efficiency and maximal W aer during speed skating. The rate of oxygen uptake (VO2) and post-exercise blood lactate concentrations ([La]) were measured and video recordings were made. W aer was calculated from VO2. W out was derived from the power needed to overcome air and ice friction. Gross efficiency was calculated as the ratio of W out and W aer. In the maximal tests, the subjects skated faster with klapskates compared to conventional skates (10.0 vs 9.6 m x s(-1)). They sustained the resulting higher W out with klapskates with an equal VO2. [La] was, however, 1.7 mmol x l(-1) higher when klapskates were used, which might reflect an increase in anaerobic power. During the submaximal tests the skaters generated equal W out with both types of skate. Although not statistically significant, VO2 and W aer were, on average, lower when klapskates were used compared to conventional skates [mean (SD) 0.3 (0.43) l x min(-1), 105 (143) W]. Despite the lack of a statistically significant difference in W aer, gross efficiency was shown to be significantly higher with klapskates compared to conventional skates (16.3% vs 14.8%, P = 0.02). We conclude that the increase in W out when the subjects were using klapskates could be explained by an increase in gross efficiency rather than an increase in W aer.