Individual Time Trial Research Articles

The Relationship Between Absolute and Relative Upper-Body Strength and Handcycling Performance Capabilities.

To explore the relationship between absolute and relative upper-body strength and selected measures of handcycling performance. A total of 13 trained H3/H4-classified male handcyclists (mean [SD] age 37 [11]y; body mass 76.6 [10.1]kg; peak oxygen consumption 2.8 [0.6]L·min-1; relative peak oxygen consumption 36.5 [10]mL·kg·min-1) performed a prone bench-pull and bench-press 1-repetition-maximum strength assessment, a 15-km individual time trial, a graded exercise test, and a 15-second all-out sprint test. Relationships between all variables were assessed using Pearson correlation coefficient. Absolute strength measures displayed a large correlation with gross mechanical efficiency and maximum anaerobic power output (P = .05). However, only a small to moderate relationship was identified with all other measures. In contrast, relative strength measures demonstrated large to very large correlations with gross mechanical efficiency, 15-km time-trial velocity, maximum anaerobic power output, peak aerobic power output, power at a fixed blood lactate concentration of 4mmol·L-1, and peak oxygen consumption (P = .05). Relative upper-body strength demonstrates a significant relationship with time-trial velocity and several handcycling performance measures. Relative strength is the product of one's ability to generate maximal forces relative to body mass. Therefore, the development of one's absolute strength combined with a reduction in body mass may influence real-world handcycling race performance.

TIME TO EXHAUSTION AT 90 AND 100% VO2MAX AND PHYSIOLOGICAL DETERMINANTS OF 3 KM PERFORMANCE IN ELITE CYCLISTS

The minimal power that elicits VO2max and the time to exhaustion (tlimit) at this workload appear to determine cyclists’ endurance capabilities, analyze performance and help coaches to design training. Data in the literature are limited so as to elucidate this. The aim of this study was to investigate the tlimit at the power output, which corresponds to 90 (tlimit 90) and 100% VO2max (tlimit 100) in elite endurance cyclists. The contribution of tlimit in 3 km indoor individual time trial was also studied. Subjects were eleven elite male road cyclists (age 17.7  0.5 years, body mass 66.8  4.9 kg, body height 176.3  7.4 cm, VO2max 69.77  2.58 ml.kg-1.min-1). Power output at 90 and 100% VO2max was determined by continuous incremental testing. This protocol had steps of 2 min and increments of 30 W. The exhaustive trials tlimit 90 or tlimit 100 were performed in random order at least five days apart. Five days after the last exhaustive trial, cyclists performed an individual 3 km time trial on an indoor wooden track. Mean sd, tlimit 90 and tlimit 100 were 16:27.73  07:46.6 and 4:48.6  00:53.2 min:sec. Time to exhaustion at tlimit 90 and tlimit 100 ranged between 07:00-30:15 and 03:10-06:00 min:sec, respectively. Tlimit 100, tlimit 90 and VO2max (ml.min-1) did not correlate with 3 km cycling performance (r = 0.08, 0.16 and –0.59, p > 0.05). Tlimit 90 was inversely related (r = –0.49, p = 0.1) with VO2max (ml.min-1). Only power output which corresponded to ventilatory threshold and VO2max correlated significantly with 3 km performance (r = –0.83 and –0.80, p < 0.01). The results of this study indicate that: a) if cyclists’ training intensity is based on %VO2max, individual determination of the tlimit at the %VO2max has to be considered due to a wide range of tlimit to exhaustion; b) 3 km performance directly depends on the power that corresponds with ventilatory threshold and VO2max.
 
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Influence of corners and road conditions on cycling individual time trial performance and ‘optimal’ pacing strategy: A simulation study

A mathematical model of a bike-rider’s longitudinal and lateral dynamics was used to study the influence of road conditions (tyre-road friction coefficient) on cycling individual time trial (ITT) performance and pacing strategy. A dynamic optimisation approach was used on different simulated 40-km-ITT courses, where environmental variables (i.e. slope and wind), the presence of corners and the tyre-road friction coefficient were varied. The objective of the optimisation was the performance time. Maximal velocity was constrained by road geometry and the tyre-road friction coefficient. The maximal deliverable power output was constrained accordingly to the critical power model. The simulation results suggest that when technical sections constitute 25% of the entire course, road conditions can meaningfully affect the final performance time and peak power required, but not the pacing strategy. In fact, the time lost in slow technical sections cannot be regained during fast straight sections, even if technical sections are used to restore anaerobic energy stores. However, more experimental research is needed to test the applicability of these predictions.

Comparison of heart rate and lactate concentration response before and after the completion of the individual time trial

Con el objetivo de comparar la frecuencia cardiaca y la respuesta de concentración de lactato antes y después de culminada la prueba de contra reloj individual en atletas de ciclismo categoría pre-juvenil de la provincia de Cotopaxi, se realizó una investigación que tuvo como impacto, la concepción de un sistema de control de la frecuencia cardiaca partir de las concentraciones de lactato en sangre de los ciclistas. Los beneficiarios son atletas pre-juveniles de la provincia de Cotopaxi, así como el cuerpo de entrenadores de este deporte en toda la provincia. El estudio se sustentó en el enfoque de los paradigmas Cuanti-cualitativo, cuantitativo porque los resultados de la investigación de campo fueron sometidos a análisis numéricos con el apoyo de la estadística. También cualitativo porque estos resultados numéricos fueron interpretados críticamente con el fin de establecer conclusiones y recomendaciones. De este mismo modo develamos una investigación factible porque garantiza la aplicación un proceso eminentemente científico en la determinación de cargas de los ciclistas, los cuales en Ecuador se ven obligados a extrapolar de otros deportes las tablas de valoración de las zonas de entrenamiento o de lo contario las seleccionan de otros países que no son somatotipica ni biológicamente iguales a los ciclistas de la región andina del Ecuador. Se obtiene como principales resultados una serie de medios y metodologías para el desarrollo de la resistencia a la velocidad.

Prediction of pacing and cornering strategies during cycling individual time trials with optimal control

A new dynamic model for predicting road cycling individual time trials with optimal control was created. The model included both lateral and longitudinal bicycle dynamics, 3D road geometry, and anaerobic source depletion. The prediction of the individual time trial performance was formulated as an optimal control problem and solved with an indirect approach to find the pacing and cornering strategies in the respect of the physical/physiological limits of the system. The model was tested against the velocity and power output data collected by professional cyclists in two individual time trial Giro d’Italia data sets: the first data set (Rovereto, n = 15) was used to adjust the parameters of the model and the second data set (Verona, n = 13) was used to test the predictive ability of the model. The simulated velocity fell in the $$\mathrm{CI}_{95\%}$$ of the experimental data for 32 and 18% of the duration of the course for Rovereto and Verona stages, respectively. The simulated power output fell in the $$\mathrm{CI}_{95\%}$$ of the experimental data for 50 and 25% of the duration of the course for Rovereto and Verona stages respectively. This framework can be used to input rider’s physical/physiological characteristics, 3D road geometry, and conditions to generate realistic velocity and power output predictions in individual time trials. It, therefore, constitutes a tool that could be used by coaches and athletes to plan the pacing and cornering strategies before the race.

The Influence of Pleasure and Attentional Focus on Performance and Pacing Strategies in Elite Individual Time Trials.

To determine the impact of pacing strategies on cyclists' mean PO during an elite TT championship and to identify the relationships between these pacing strategies and psychological parameters. Mean PO, projected frontal area, attentional focus, and pleasure were recorded for 9 male cyclists during an official individual TT national championship. Pacing regulations were quantified from PO using the new exposure variation analysis, which determines times spent at adapted PO for optimal constant-pacing strategy (APO) and inaccurate PO for optimal constant-pacing strategy (IPO). Relationships between mean PO, times spent at APO and IPO, and psychological variables were analyzed. Significant relationships were found between mean PO and exposure variation analysis pacing parameters (r2 .56-.86, P > .05). Time spent at IPO was negatively related to pleasure during the individual TT (r = -.746, P = .016). Conversely, time spent at APO was significantly related to cyclists' attentional focus (r = .827, P = .006). Mean PO during elite individual TTs is directly related to athletes' ability to optimally regulate pace throughout the event. This pacing regulation is influenced by attentional focus and pleasure, underlining that coaches and athletes should devote greater attention to these psychological parameters to improve their performances.

Adaptive feedback system for optimal pacing strategies in road cycling

In road cycling, the pacing strategy plays an important role, especially in solo events like individual time trials. Nevertheless, not much is known about pacing under varying conditions. Based on mathematical models, optimal pacing strategies were derived for courses with varying slope or wind, but rarely tested for their practical validity. In this paper, we present a framework for feedback during rides in the field based on optimal pacing strategies and methods to update the strategy if conditions are different than expected in the optimal pacing strategy. To update the strategy, two solutions based on model predictive control and proportional–integral–derivative control, respectively, are presented. Real rides are simulated inducing perturbations like unexpected wind or errors in the model parameter estimates, e.g., rolling resistance. It is shown that the performance drops below the best achievable one taking into account the perturbations when the strategy is not updated. This is mainly due to premature exhaustion or unused energy resources at the end of the ride. Both the proposed strategy updates handle those problems and ensure that a performance close to the best under the given conditions is delivered.

Physical demands and power profile of different stage types within a cycling grand tour

This study aims to describe the intensity and load demands of different stage types within a cycling Grand Tour. Nine professional cyclists, whom are all part of the same World-Tour professional cycling team, participated in this investigation. Competition data were collected during the 2016 Giro d’Italia. Stages within the Grand Tour were classified into four categories: flat stages (FLAT), semi-mountainous stages (SMT), mountain stages (MT) and individual time trials (TT). Exercise intensity, measured with different heart rate and power output based variables, was highest in the TT compared to other stage types. During TT’s the main proportion of time was spent at the high-intensity zone, whilst the main proportion of time was spent at low intensity for the mass start stage types (FLAT, SMT, MT). Exercise load, quantified using Training Stress Score and Training Impulse, was highest in the mass start stage types with exercise load being highest in MT (329, 359 AU) followed by SMT (280, 311 AU) and FLAT (217, 298 AU). Substantial between-stage type differences were observed in maximal mean power outputs over different durations. FLAT and SMT were characterised by higher short-duration maximal power outputs (5–30 s for FLAT, 30 s–2 min for SMT) whilst TT and MT are characterised by high longer duration maximal power outputs (>10 min). The results of this study contribute to the growing body of evidence on the physical demands of stage types within a cycling Grand Tour.

Core temperature up to 41.5ºC during the UCI Road Cycling World Championships in the heat

ObjectiveTo characterise the core temperature response and power output profile of elite male and female cyclists during the 2016 UCI Road World Championships. This may contribute to formulating environmental heat...

Exercise Intensity During Cross-Country Skiing Described by Oxygen Demands in Flat and Uphill Terrain.

Purpose: In this study wearable global navigation satellite system units were used on athletes to investigate pacing patterns by describing exercise intensities in flat and uphill terrain during a simulated cross-country ski race.Methods: Eight well-trained male skiers (age: 23.0 ± 4.8 years, height: 183.8 ± 6.8 cm, weight: 77.1 ± 6.1 kg, VO2peak: 73 ± 5 mL⋅kg-1⋅min-1) completed a 13.5-km individual time trial outdoors and a standardized indoor treadmill protocol on roller skis. Positional data were recorded during the time trial using a differential global navigation satellite system to calculate external workloads in flat and uphill terrain. From treadmill tests, the individual relationships between oxygen consumption and external workload in flat (1°) and uphill (8°) terrain were determined, in addition to VO2peak and the maximal accumulated O2-deficit. To estimate the exercise intensity in the time trial, the O2-demand in two different flat and five different uphill sections was calculated by extrapolation of individual O2-consumption/workload ratios.Results: There was a significant interaction between section and average O2-demands, with higher O2-demands in the uphill sections (110–160% of VO2peak) than in the flat sections (≤100% of VO2peak) (p < 0.01). The maximal accumulated O2-deficit associated with uphill treadmill roller skiing was significantly higher compared to flat (6.2 ± 0.5 vs. 4.6 ± 0.5 L, p < 0.01), while no significant difference was found in VO2peak.Conclusion: Cross-country (XC) skiers repeatedly applied exercise intensities exceeding their maximal aerobic power. ΣO2-deficits were higher during uphill skiing compared to flat which has implications for the duration and magnitude of supramaximal work rates that can be applied in different types of terrain.

How to Stay Ahead of the Pack: Optimal Road Cycling Strategies for two Cooperating Riders

Abstract Within road-cycling, the optimization of performance using mathematical models has primarily been performed in the individual time trial. Nevertheless, most races are 'mass-start' events in which many riders compete at the same time. In some special situations, e.g. breakaways from the peloton, the riders are forced to team up. To simulate those cooperative rides of two athletes, an extension of models and optimization approaches for individual time trials is presented. A slipstream model based on experimental data is provided to simulate the physical interaction between the two riders. In order to simulate real world behavior, a penalty for the difference in the exertion levels of the two riders is introduced. This means, that even though both riders aim to be as fast as possible as a group, neither of them should have an advantage over the other because of significantly different levels of fatigue during the ride. In our simulations, the advantage of cooperation of two equally trained athletes adds up to a time gain of about 10% compared to an individual ride.

Analysis of the effect of helmet shape and head position on performance during time-trial cycling

Cycling science has undergone a great revolution in recent years. During individual time-trials, racing events in which cyclists race against the clock are not permitted to ride behind other cyclis...

The individual time trial as an optimal control problem.

In a cycling time trial, the rider needs to distribute his power output optimally to minimize the time between start and finish. Mathematically, this is an optimal control problem. Even for a straight and flat course, its solution is non-trivial and involves a singular control, which corresponds to a power that is slightly above the aerobic level. The rider must start at full anaerobic power to reach an optimal speed and maintain that speed for the rest of the course. If the course is flat but not straight, then the speed at which the rider can round the bends becomes crucial.

자전거 운동 중 클릿의 위치 변화에 따른 페달링 수행능력 비교

The purpose of this research is to investigate the effects of different shoe-cleat position on pedalling performance. Four male elite triathletes(age: 22.00±2.16years, height: 175.12±8.06cm, weight: 71.20±7.89kg, body fat: 16.62±3.56%) and three female elite triathletes(age: 20.00±1years, height: 158.40±2.42cm, weight: 51.30±3.89kg, body fat: 19.26±2.28%) participated in 10km time trial and 30sec time trial pedaling tests with the individual time trials based on different shoe-cleat position(cleat front: CF, cleat back: CB). The subjects performed one trial with each type of shoe-cleat position. Maximal power output and average speed were not significantly different during 30s time trial in CF compared with CB. Average power, RPM, and HR were not significantly different during 10k time trial in CF compared with CB. Split time in 1km, 5km, 9km were significantly reduced during 10k time trial in CB compared with CF. We conclude that there was performance advantage in CB using shoe-cleat back position in comparison with CF using shoe-cleat front position.

Exposure Variation Analysis (EVA) method to monitor ability to optimally regulate exercise intensity of professional cyclists during time-trial competitions

Introduction Pacing strategies during endurance performance is becoming one of the main topics in sport sciences. Several studies proved that a constant pacing strategy, adjusted from course main difficulties, is optimal for individual time-trial (ITT) performance. However, the regulation mechanisms that allow athletes to maintain a constant power output (PO) remain poorly studied (Abbiss and Laursen 2008). The “Exposure Variation Analysis” (EVA) was recently proposed as a new innovative method to quantify short-time PO fluctuations during ITT (Abbiss et al. 2010; Peiffer and Abbiss 2011). This method appears to offer an interesting way to investigate the athlete ability to optimally regulate exercise intensity during ITT in order to maintain a constant optimal pacing strategy. The aim of this study was to assess the relationship between the exercise intensity regulation mechanisms quantified thanks to the EVA method and the evolutions of performance of Word-Tour cyclists during an official competitive ITT performed on the same course during two consecutive years.  Methods After a maximal exhaustive aerobic test, a group of physically active individuals and trained cyclists (N= 12; MAP 352 ± 49 W) in randomized order performed one FTP test over 20 minutes (FTP20) and one CP test, comprising of maximal time trial efforts (TT) of 12 min, 7 min and 3 min, interspersed by 30 min rest (9). Tests were performed on a Cyclus2 ergometer (RBM Elektronik GmbH, Leipzig, Germany). During TTs and FTP test, participants utilised a self-pacing strategy were gearing was adjusted throughout efforts using the virtual gear changer mounted to the handlebars. CP was determined using the power-inverse time model (P = Wi‚¢(1/t) + CP) and FTP60 was calculated as 95% of the FTP20 mean PO. Differences of statistical significance between CP and FTP values were tested using a paired samples t-tests. Relationships were assessed using Pearson product moment correlation coefficients. The agreement between CP and FTP60 values was assessed using Limits of Agreement (LoA). Linear regression was used to calculate the standard error of estimate (SEE) associated with predicting FTP60 values as well as for individual CP values.  Results The mean difference between CP and FTP60 values was 5 ± 11 W, which was non-significant (t(11) = 1.7, p = .108). LoA between values were -38 – 29 W (Fig 1A). The standard error associated with the prediction of FTP60 was 18 W (Cl, 13 - 28W), when expressed as percentage error resulted in 7.9% (Cl, 5.8 – 12.9%). The correlation between CP and FTP60 values was r = 0.93, P ≤ 0.001 (Fig 1B). The mean SEE for CP values was 4 ± 2 W.  Discussion Results demonstrate low LoA between CP and FTP60 values and a high prediction error when using a group of mixed trained athletes. This suggests that CP and FTP60 results cannot be used interchangeably. By using more than one data point, an advantage of CP over FTP60 is a reduction in random error (expressed as SEE). This can be useful for coaches as it minimizes the biological re-test variability caused by the athlete. CP testing also allows the determination of W', i.e. the maximum amount of work that can be expended above the intensity of CP. It therefore offers more information about the performance capabilities of an athlete. With some agreement present for the trained cyclists, future studies should focus on this population.  Conclusion For a same ITT, mean PO of a professional cyclist remain extremely stable over years. Accordingly, he will be more able to improve his performance thanks to a better effort regulation than by increasing his mean PO. EVA method appears to be an innovative tool to evaluate cyclists’ ability to optimally regulate exercise intensity during ITT.

Comparison of the effect of intermittent hypoxic training vs. the live high, train low strategy on aerobic capacity and sports performance in cyclists in normoxia.

The aim of the study was to compare the effect of intermittent hypoxic training (IHT) and the live high, train low strategy on aerobic capacity and sports performance in off-road cyclists in normoxia. Thirty off-road cyclists were randomized to three groups and subjected to 4-week training routines. The participants from the first experimental group were exposed to normobaric hypoxia conditions (FiO2 = 16.3%) at rest and during sleep (G-LH-TL; n=10; age: 20.5 ± 2.9 years; body height 1.81 ± 0.04 m; body mass: 69.6 ± 3.9 kg). Training in this group was performed under normoxic conditions. In the second experimental group, study participants followed an intermittent hypoxic training (IHT, three sessions per week, FiO2 = 16.3%) routine (G-IHT; n=10; age: 20.7 ± 3.1 years; body height 1.78 ± 0.05 m; body mass: 67.5 ± 5.6 kg). Exercise intensity was adjusted based on the lactate threshold (LT) load determined in hypoxia. The control group lived and trained under normoxic conditions (G-C; n=10; age: 21.8 ± 4.0 years; body height 1.78 ± 0.03 m; body mass: 68.1 ± 4.7 kg; body fat content: 8.4 ± 2.4%). The evaluations included two research series (S1, S2). Between S1 and S2, athletes from all groups followed a similar training programme for 4 weeks. In each research series a graded ergocycle test was performed in order to measure VO2max and determine the LT and a simulated 30 km individual time trial. Significant (p<0.05) improvements in VO2max, VO2LT, WRmax and WRLT were observed in the G-IHT (by 3.5%, 9.1%, 6.7% and 7.7% respectively) and G-LH-TL groups (by 4.8%, 6.7%, 5.9% and 4.8% respectively). Sports performance (TT) was also improved (p<0.01) in both groups by 3.6% in G-LH-TL and 2.5% in G-IHT. Significant changes (p<0.05) in serum EPO levels and haematological variables (increases in RBC, HGB, HCT and reticulocyte percentage) were observed only in G-LH-TL. Normobaric hypoxia has been demonstrated to be an effective ergogenic aid that can enhance the exercise capacity of cyclists in normoxia. Both LH-TL and IHT lead to improvements in aerobic capacity. The adaptations induced by both approaches are likely to be caused by different mechanisms. The evaluations included two research series (S1, S2). Between S1 and S2, athletes from all groups followed a similar training programme for 4 weeks. In each research series a graded ergocycle exercise test was performed in order to measure VO2max and determine the lactate threshold as well as a simulated 30 km individual time trial.

The process of losing – investigating the psychophysiological determinants of pacing and performance during head-to-head competition

Introduction It is widely accepted that psychological factors can greatly influence human endurance and strength performance. However, little is known about the mechanisms that underpin facilitative and even more so debilitative cause-effect relationships between psychological factors and endurance performance during competition.[1] We recently developed a three-dimensional framework of centrally-regulated and goal-directed exercise behaviour emphasizing the important role of sensory-discriminatory, affective-motivational, and cognitive-evaluative processes underpinning observed pacing behaviour and performance.[2] The proposed framework offers a more sophisticated alternative to the traditional gestalt concept of perceived exertion in the investigation of the psychophysiological determinants of pacing and performance during prolonged endurance exercise. One aim of this experimental study was to examine the delineated contributions of the perceptual sensory, affective, and cognitive processes and their dynamic responses to respectively pulling ahead or falling behind a performance matched opponent.[3]  Methods Fourteen maximal head-to-head competition time trials between well-trained performance matched cyclists (average time difference in individual time trial performance: 0.92%) over a 70 km virtual profiled course were conducted. The sensory, affective, and cognitive processes were approximated by means of scales: perceived physical (p-RPE) and mental strain (TEA), affective valence (FS) and felt arousal (FAS), and perceived action crisis (ACRISS), respectively. The dynamic changes in these constructs and their interrelationships with pacing behaviour, performance, and markers of metabolic and endocrinological distress were investigated. A five-step structural equation modelling procedure was applied to test the extent to which the observed data fit the hypothesized temporally linked cause-effect relationships unfolding in response to falling-behind a performance matched opponent. [4] Results Meaningful performance improvements of 2.24% (99.7% most likely substantially positive) and decrements 1.69% (82.4% likely substantially negative) were found in winners and losers, respectively. Perceived physical and mental strain scaled with time and according to course profile in winners and loser alike. The following significant interaction effects were found: losers showed deterioration in valence (p=0.004), experienced the development of an action crisis (p<0.001), showed increased blood cortisol concentrations (p=0.001), and performance decrement relative to individual’s performance capabilities (p=0.001) (see figure 1). The dynamic change in valence was a significant mediator (p=0.011) in performance regulation as it explained 35% of the relationship between falling behind and action crisis. The shift from an implemental to a deliberative mindset associated with an action crisis was a significant predictor of exacerbated psycho-neuro-endocrinological distress response (p=0.024) and non-adaptive endocrinological distress response subsequently predicted relative performance decrement (p=0.023). The observed data fitted the hypothesized model well with excellent model fit indices throughout.  Conclusions We applied, tested, and confirmed the hypothesized debilitative psychophysiological processes that unfold in response to falling behind a performance matched opponent. The main findings were: a) perceived physical and mental strain play primary roles in the teleoanticipatory pacing algorithm necessary to align planned behaviour with current physiological state; but both can be distorted by centrally-acting affective and cognitive modifiers, b) deterioration in non-reflective valence mediated the relationship between falling behind and reflective action crisis, c) the mindset-shift associated with an action crisis predicted exacerbated blood cortisol concentrations, and d) non-adaptive blood cortisol concentrations predicted performance decrement. The findings point towards the primary and mediatory roles of core affect and mindset in perceived fatigability and the psychophysiological determinants of pacing and performance. The proposed three-dimensional framework has the potential to markedly improve our ability to explain something as complex and multi-faceted as centrally-regulated and goal-directed exercise behaviour.  Â

Eficiencia de las salidas frontal y lateral para la prueba de pista 300 metros CRI, patinaje de velocidad sobre ruedas

Se valoró, con los elementos que éste contiene –análisis y evaluación-, Biomecánicamente, con el protocolo empleado por Bohórquez, D. et al., (2014), desde el plano sagital izquierdo, la Salida Frontal (SF) y la Salida Lateral (SL) en pruebas de velocidad de pista Contra el Reloj Individual (CRI), de once (11) Patinadores de Velocidad Sobre Ruedas (VSR), empleando el Software SIMI°Twinner Pro y el software SPSS (versión 19); lo que permitió determinar que la SL es más eficiente que la SF para el desarrollo de la prueba de pista 300 metros CRI en el patinaje de VSR.Palabras clave: patinaje de velocidad sobre ruedas; pruebas de velocidad Contra el Reloj Individual; salida frontal; salida lateral; trocánter izquierdo; in-line speed skating; individual time trials raced against the clock; front start; side start; left trochanter; upper hip

A following car influences cyclist drag: CFD simulations and wind tunnel measurements

It is well-known in elite cycling that a cyclist riding behind a car experiences a substantial reduction in aerodynamic resistance or drag. However, the upstream effect by a following car on the cyclist in front of it is not well-known and has, to the best of our knowledge, not yet been reported in the scientific literature. It is also not taken into account in elite cycling, as for individual time trials, the rules of the International Cycling Union (UCI) only specify a minimum distance between rider and car of 10m because of safety reasons. Furthermore, during actual races, this limit is often not kept and not strictly enforced. Nevertheless, during individual time trials, there is always at least one, but often more, following cars, potentially influencing the cyclist drag. This study presents the results of CFD simulations and wind tunnel measurements to ascertain and quantify the upstream effect by a following car on the drag of the cyclist in front of it. CFD simulations are performed based on the steady-state Reynolds-Averaged Navier–Stokes equations with the standard k–ε model for closure. The simulations are validated based on a series of wind tunnel measurements. The drag reduction for the cyclist ranges from 3.7% over 1.4% to 0.2% for realistic separation distances of 3, 5 and 10m, respectively. For a typical 50km individual time trial, the potential time reduction by exploiting this effect (e.g. by a car following the rider at this short distance versus no car behind) is 62.4s, 24.1s and 3.9s, respectively. As elite cyclist time trials are often won based on seconds or sometimes even less, these differences can be decisive for who wins the stage. Therefore, it is recommended that the UCI not only raises its current minimum separation distance of 10m to at least 30m, but also strictly enforces it, to avoid this unwanted aerodynamic effect that can influence the outcome of the race.

Speed and heart-rate profiles in skating and classical cross-country skiing competitions.

To compare the speed and heart-rate profiles during international skating and classical competitions in male and female world-class cross-country skiers. Four male and 5 female skiers performed individual time trials of 15 km (men) and 10 km (women) in the skating and classical techniques on 2 consecutive days. Races were performed on the same 5-km course. The course was mapped with GPS and a barometer to provide a valid course and elevation profile. Time, speed, and heart rate were determined for uphill, flat, and downhill terrains throughout the entire competition by wearing a GPS and a heart-rate monitor. Times in uphill, flat, and downhill terrain were ~55%, 15-20%, and 25-30%, respectively, of the total race time for both techniques and genders. The average speed differences between skating and classical skiing were 9% and 11% for men and women, respectively, and these values were 12% and 15% for uphill, 8% and 13% for flat (all P < .05), and 2% and 1% for downhill terrain. The average speeds for men were 9% and 11% faster than for women in skating and classical, respectively, with corresponding numbers of 11% and 14% for uphill, 6% and 11% for flat, and 4% and 5% for downhill terrain (all P < .05). Heart-rate profiles were relatively independent of technique and gender. The greatest performance differences between the skating and classical techniques and between the 2 genders were found on uphill terrain. Therefore, these speed differences could not be explained by variations in exercise intensity.