Field- and Laboratory-derived Power-Cadence Profiles in World-Class and Elite Track Sprint Cyclists.

Previous investigations comparing Torque-Cadence (T-C) and Power-Cadence (P-C) profiles derived from seated and standing positions and field and laboratory conditions are not congruent with current methodological recommendations. Consequently, the aim of this investigation was to compare seated and standing T-C and P-C profiles generated from field and laboratory testing. Thirteen world-class and elite track sprint cyclists (n = 7 males, maximal power output (Pmax) = 2112 ± 395 W; n = 6 females, Pmax = 1223 ± 102 W) completed two testing sessions in which field- and laboratory-derived T-C and P-C profiles were identified. Standing P-C profiles had significantly (p < 0.05) greater Pmax than seated profiles, however there were no significant differences in optimal cadence (Fopt) between seated and standing positions. Pmax and Fopt were significantly lower in field-derived profiles in both positions compared to laboratory-derived profiles. However, there was no significant difference in the goodness-of-fit (R2) of the P-C profiles between laboratory (0.985 ± 0.02) and field-testing (0.982 ± 0.02) in each position. Valid T-C and P-C profiles can be constructed from field and laboratory protocols; however, the mechanical variables derived from the seated and standing and field and laboratory profiles cannot be used interchangeably. Both field and laboratory-derived profiles provide meaningful information and provide complementary insights into cyclists' capacity to produce power output.

The influence of cadence on fatigue during maximal sprint cycling in world-class and elite sprint cyclists.

Optimising cadence through appropriate gear selection is a key consideration for track sprint cycling performance, yet the influence of cadence on fatigue (i.e., decrement in power output) within a maximal sprint is not well understood. The aim of this study was to identify the influence of cadence on fatigue during maximal sprint cycling. Eleven world-class and elite track sprint cyclists (n = 6 men, maximal power output (Pmax) = 1894 ± 351 W, optimal cadence (Fopt) = 134 ± 8 rev∙min-1: n = 5 women, Pmax = 1114 ± 80 W, Fopt = 124 ± 8 rev∙min-1) completed two testing sessions where power-cadence profiles were constructed to determine the Fopt associated with Pmax. Cyclists also performed three maximal 15-s sprints (Fopt, ±15%Fopt) to identify fatigue per pedal stroke across these cadence ranges. There was no significant difference (p = 0.2) in the absolute fatigue per pedal stroke when cadence was fixed 15% above (16.7 ± 6.1 W∙stroke-1) and below (15.3 ± 5.1 W∙stroke-1) Fopt. Similarly, there was no significant difference in the relative fatigue per pedal stroke (% peak power∙stroke-1) across Fopt and ± 15%Fopt trials (p = 0.12). The relative decrement in power output is equivalent across the ± 15%Fopt cadence range. As such, a higher-geared, lower-cadence approach to maximal sprint cycling could be a viable method to minimise maximal pedal strokes and reduce the decrement in power output.

Assessment of bike handling during cycling individual time trials with a novel analytical technique adapted from motorcycle racing.

A methodology to study bike handling of cyclists during individual time trials (ITT) is presented. Lateral and longitudinal accelerations were estimated from GPS data of professional cyclists (n = 53) racing in two ITT of different length and technical content. Acceleration points were plotted on a plot (g-g diagram) and they were enclosed in an ellipse. A correlation analysis was conducted between the area of the ellipse and the final ITT ranking. It was hypothesised that a larger area was associated with a better performance. An analytical model for the bike-cyclist system dynamics was used to conduct a parametric analysis on the influence of riding position on the shape of the g-g diagram. A moderate (n = 27, r = -0.40, p = 0.038) and a very large (n = 26, r = -0.83, p < 0.0001) association were found between the area of the enclosing ellipse and the final ranking in the two ITT. Interestingly, this association was larger in the shorter race with higher technical content. The analytical model suggested that maximal decelerations are highly influenced by the cycling position, road slope and speed. This investigation, for the first time, explores a novel methodology that can provide insights into bike handling, a large unexplored area of cycling performance.

Testing, Training, and Optimising Performance of Track Cyclists: A Systematic Mapping Review.

BACKGROUND: Track cyclists must develop mental, physical, tactical and technical capabilities to achieve success at an elite level. Given the importance of these components in determining performance, it is of interest to understand the volume of evidence to support implementation in practice by coaches, practitioners, and athletes. OBJECTIVE: The aim of this study was to conduct a systematic mapping review to describe the current scale and density of research for testing, training and optimising performance in track cycling. METHODS: All publications involving track cyclist participants were reviewed from four databases (PubMed, SPORTDiscus, Academic Search Complete, Cochrane Library) plus additional sources. Search results returned 4019 records, of which 71 met the inclusion criteria for the review. RESULTS: The review revealed most published track cycling research investigated athlete testing followed by performance optimisation, with training being the least addressed domain. Research on the physical components of track cycling has been published far more frequently than for tactical or technical components, and only one study was published on the mental components of track cycling. No true experimental research using track cyclists has been published, with 51 non-experimental and 20 quasi-experimental study designs. CONCLUSIONS: Research in track cycling has been growing steadily. However, it is evident there is a clear preference toward understanding the physical-rather than mental, tactical, or technical-demands of track cycling. Future research should investigate how this aligns with coach, practitioner, and athlete needs for achieving track cycling success. REGISTRATION: This systematic mapping review was registered on the Open Science Framework (osf.io/wt7eq).

Training Load and Its Role in Injury Prevention, Part I: Back to the Future.

The purpose of this 2-part commentary series is† to explain why we believe our ability to control injury risk by manipulating training load (TL) in its current state is an illusion and why the foundations of this illusion are weak and unreliable. In part 1, we introduce the training process framework and contextualize the role of TL monitoring in the injury-prevention paradigm. In part 2, we describe the conceptual and methodologic pitfalls of previous authors who associated TL and injury in ways that limited their suitability for the derivation of practical recommendations. The first important step in the training process is developing the training program: the practitioner develops a strategy based on available evidence, professional knowledge, and experience. For decades, exercise strategies have been based on the fundamental training principles of overload and progression. Training-load monitoring allows the practitioner to determine whether athletes have completed training as planned and how they have coped with the physical stress. Training load and its associated metrics cannot provide a quantitative indication of whether particular load progressions will increase or decrease the injury risk, given the nature of previous studies (descriptive and at best predictive) and their methodologic weaknesses. The overreliance on TL has moved the attention away from the multifactorial nature of injury and the roles of other important contextual factors. We argue that no evidence supports the quantitative use of TL data to manipulate future training with the purpose of preventing injury. Therefore, determining "how much is too much" and how to properly manipulate and progress TL are currently subjective decisions based on generic training principles and our experience of adjusting training according to an individual athlete's response. Our message to practitioners is to stop seeking overly simplistic solutions to complex problems and instead embrace the risks and uncertainty inherent in the training process and injury prevention.

Power output, cadence, and torque are similar between the forward standing and traditional sprint cycling positions.

PURPOSE: Compare power output, cadence, and torque in the seated, standing, and forward standing cycling sprint positions. METHODS: On three separated occasions (ie, one for each position), 11 recreational male road cyclists performed a 14 seconds sprint before and directly after a high-intensity lead-up. Power output, cadence, and torque were measured during each sprint. RESULTS: No significant differences in peak and mean power output were observed between the forward standing (1125.5 ± 48.5 W and 896.0 ± 32.7 W, respectively) and either the seated or standing positions (1042.5 ± 46.8 W and 856.5 ± 29.4 W; 1175.4 ± 44.9 W and 927.5 ± 28.9 W, respectively). Power output was higher in the standing, compared with the seated position. No difference was observed in cadence between positions. At the start of the sprint before the lead-up, peak torque was higher in the standing position vs the forward standing position; and peak torque occurred later in the pedal revolution for both the forward standing and standing positions when compared with the seated position. At the start of the sprint after the lead-up, peak torque occurred later in the forward standing position when compared with both the seated and standing position. At the end of the sprint, no difference in torque was found between the forward standing and standing position either before or after the lead-up. CONCLUSION: Sprinting in the forward standing sprint position does not impair power output, cadence, and torque when compared with the seated and standing sprint positions.

Racing weight and resistance training: perceptions and practices in trained male cyclists.

Objectives: This study sought to investigate the perceptions and practices of achieving 'race weight' in a population of trained male cyclists. A secondary focus was to investigate the use of gym-based strength training, a possible attenuator of the side effects associated with weight reduction.Methods: A total of n = 97 well-trained cyclists ranging from local club level to international standard completed an online survey capturing data on the aforementioned topics.Results: Forty-nine percent of respondents indicated they were unsatisfied with their current bodyweight, with a similar percentage across club, national and international level riders. Riders who identified as climbers had lower reported bodyweight; however, all categories of riders expressed a desire to reduce bodyweight by a similar percentage (1.9%, ± 3.4%; 90% CL). Seventy-seven percent of respondents indicated that they had recently tried or were currently trying to reduce bodyweight, most commonly by reducing food intake and avoiding sugary foods. Nine percent indicated they were using either supplements or medications to lower bodyweight, and 27% reported having sought advice from a health professional. A higher proportion of international riders engaged in strength training (85%), compared to national (50%) and club (55%) riders (p< 0.05). The most cited reasons for not strength training were time constraints and believing it was not beneficial to their cycling performance.Conclusion: These data suggest that trained male cyclists are a highly weight-conscious population who engage in a variety of practices to reduce weight. Practitioners should be aware of these tendencies, as they may carry significant health implications if poorly implemented.

Validity of the Velocomp PowerPod Compared With the Verve Cycling InfoCrank Power Meter.

PURPOSE: To determine the validity of the Velocomp PowerPod power meter in comparison with the Verve Cycling InfoCrank power meter. METHODS: This research involved 2 separate studies. In study 1, 12 recreational male road cyclists completed 7 maximal cycling efforts of a known duration (2 times 5 s and 15, 30, 60, 240, and 600 s). In study 2, 4 elite male road cyclists completed 13 outdoor cycling sessions. In both studies, power output of cyclists was continuously measured using both the PowerPod and InfoCrank power meters. Maximal mean power output was calculated for durations of 1, 5, 15, 30, 60, 240, and 600 seconds plus the average power output in study 2. RESULTS: Power output determined by the PowerPod was almost perfectly correlated with the InfoCrank (r > .996; P < .001) in both studies. Using a rolling resistance previously reported, power output was similar between power meters in study 1 (P = .989), but not in study 2 (P = .045). Rolling resistance estimated by the PowerPod was higher than what has been previously reported; this might have occurred because of errors in the subjective device setup. This overestimation of rolling resistance increased the power output readings. CONCLUSION: Accuracy of rolling resistance seems to be very important in determining power output using the PowerPod. When using a rolling resistance based on previous literature, the PowerPod showed high validity when compared with the InfoCrank in a controlled field test (study 1) but less so in a dynamic environment (study 2).

Effect of Environmental Temperature on High-Intensity Intervals in Well-Trained Cyclists.

PURPOSE: To examine the effect of environmental temperature (TA) on performance and physiological responses (eg, body temperature, cardiopulmonary measures) during a high-intensity aerobic interval session. It was hypothesized that power output would be highest in the 13°C condition and lower in the 5°C, 22°C, and 35°C conditions. METHODS: Eleven well-trained cyclists randomly completed 4 interval sessions at 5°C, 13°C, 22°C, and 35°C (55% [13%] relative humidity), each involving five 4-min intervals interspersed with 5 min of recovery. During the intervals, power output, core temperature (TC), skin temperature, VO2, and heart rate were recorded. RESULTS: Mean session power output for 13°C (366 [32] W) was not higher than 5°C (363 [32] W; P = 1.00, effect size = 0.085), 22°C (364 [36] W; P = 1.00, effect size = 0.061), or 35°C (352 [31] W; P = .129, effect size = 0.441). The 5th interval of the 35°C condition had a lower power output compared with all other TA. TC was higher in 22°C compared with both 5°C and 13°C (P = .001). VO2 was not significantly different across TA (P = .187). Heart rate was higher in the 4th and 5th intervals of 35°C compared with 5°C and 13°C. CONCLUSIONS: This study demonstrates that while mean power outputs for intervals are similar across TA, hot TA (≥35°C) reduces interval power output later in a training session. Well-trained cyclists performing maximal high-intensity aerobic intervals can achieve near-optimal power output over a broader range of TA than previous literature would indicate.

Reducing Aerodynamic Drag by Adopting a Novel Road-Cycling Sprint Position.

PURPOSE: To assess the influence of seated, standing, and forward-standing cycling sprint positions on aerodynamic drag (CdA) and the reproducibility of a field test of CdA calculated in these different positions. METHODS: A total of 11 recreational male road cyclists rode 250 m in 2 directions at around 25, 32, and 40 km·h-1 and in each of the 3 positions, resulting in a total of 18 efforts per participant. Riding velocity, power output, wind direction and velocity, road gradient, temperature, relative humidity, and barometric pressure were measured and used to calculate CdA using regression analysis. RESULTS: A main effect of position showed that the average CdA of the 2 d was lower for the forward-standing position (0.295 [0.059]) compared with both the seated (0.363 [0.071], P = .018) and standing positions (0.372 [0.077], P = .037). Seated and standing positions did not differ from each other. Although no significant difference was observed in CdA between the 2 test days, a poor between-days reliability was observed. CONCLUSION: A novel forward-standing cycling sprint position resulted in 23% and 26% reductions in CdA compared with a seated and standing position, respectively. This decrease in CdA could potentially result in an important increase in cycling sprint velocity of 3.9-4.9 km·h-1, although these results should be interpreted with caution because poor reliability of CdA was observed between days.

Sprinting for the Win: Distribution of Power Output in Women's Professional Cycling.

PURPOSE: To examine the power-output distribution and sprint characteristics of professional female road cyclists. METHODS: A total of 31 race files, representing top 5 finishes, were collected from 7 professional female cyclists. Files were analyzed for sprint characteristics, including mean and peak power output, velocity, and duration. The final 20 min before the sprint was analyzed to determine the mean maximal power output (MMP) consistent with durations of 5, 15, 30, 60, 240, and 600 s. Throughout the race, the number of efforts for each duration exceeding 80% of its corresponding final 20-min MMP (MMP80) was determined. The number of 15-s efforts exceeding 80% of the mean final sprint power output (MSP80) was determined. RESULTS: Sprint finishes lasted 21.8 (6.7) s with mean and peak power outputs of 679 (101) and 886 (91) W, respectively. Throughout the race, additional 5-, 15-, and 30-s efforts above MMP80 were completed in the 5th compared with the 1st-4th quintiles of the race. The 60-s efforts were greater during the 5th quintile compared with the 1st, 2nd, and 4th quintiles, and during the 3rd compared with the 4th quintile. More 240-s efforts were recorded during the 5th compared with the 1st and 4th quintiles. About 82% of the 15-s efforts above MSP80 were completed in the 2nd, 3rd, and 5th quintiles of the race. CONCLUSIONS: These data demonstrate the variable nature of women's professional cycling and the physical demands necessary for success, thus providing information that could enhance in-race decision making and the development of race-specific training programs.

Validity of the Online Athlete Management System to Assess Training Load.

PURPOSE: To validate the quantification of training load (session rating of perceived exertion [s-RPE]) in an Australian Olympic squad (women's water polo), assessed with the use of a modified RPE scale collected via a newly developed online system (athlete management system). METHODS: Sixteen elite women water polo players (age = 26 [3] y, height = 1.78 [0.05] m, and body mass = 75.5 [7.1] kg) participated in the study. Thirty training sessions were monitored for a total of 303 individual sessions. Heart rate was recorded during training sessions using continuous heart-rate telemetry. Participants were asked to rate the intensity of the training sessions on the athlete management system RPE scale, using an online application within 30 min of completion of the sessions. Individual relationships between s-RPE and both Banister training impulse (TRIMP) and Edwards' method were analyzed. RESULTS: Individual correlations with s-RPE ranged between r = .51 and .79 (Banister TRIMP) and r = .54 and .83 (Edwards' method). The percentages of moderate and large correlation were 81% and 19% between s-RPE method and Banister TRIMP, and 56% and 44% between s-RPE and Edwards' method. CONCLUSIONS: The online athlete management system for assessing s-RPE was shown to be a valid indicator of internal training load and can be used in elite sport.

Achieving Grand Tour success: a pilot study using cycling's World Tour points.

BACKGROUND: In cycling, the Union Cycliste International (UCI) World Tour points system provides a basis to assess the development of riders by longitudinally monitoring accumulated points. The main aim of the present analysis was to compare the annual aggregation of points of Grand Tours (GT) contenders during the years before and the year after achieving an overall top-ten (T10) placing in a GT for the first time. METHODS: Data from professional cyclists who achieved their first T10 general classification result in a GT between 2010 and 2015, inclusive, were included in the analysis. RESULTS: There were 43 cyclists who achieved a T10 placing for the first time between 2010 and 2015, with an average number of UCI points of 139.7±77.1 points. Of these cyclists, 20 placed within the top five (T5), and averaged 183.1±71.6 UCI points within the T5 season. There was a significant difference in the number of points accumulated in the T5/T10 between the T5 and T10 groups (P<0.05), however there were no significant differences between the groups in the other seasons. CONCLUSIONS: An apparent spike in the number of points obtained in the T5 or T10 season when compared to the preceding seasons may be due to successful riders being afforded more opportunities to play leading roles within the team. This effect may have persisted into the season following the T5/T10 finish.

Considerations on the Assessment and Use of Cycling Performance Metrics and their Integration in the Athlete's Biological Passport.

Over the past few decades the possibility to capture real-time data from road cyclists has drastically improved. Given the increasing pressure for improved transparency and openness, there has been an increase in publication of cyclists' physiological and performance data. Recently, it has been suggested that the use of such performance biometrics may be used to strengthen the sensitivity and applicability of the Athlete Biological Passport (ABP) and aid in the fight against doping. This is an interesting concept which has merit, although there are several important factors that need to be considered. These factors include accuracy of the data collected and validity (and reliability) of the subsequent performance modeling. In order to guarantee high quality standards, the implementation of well-structured Quality-Systems within sporting organizations should be considered, and external certifications may be required. Various modeling techniques have been developed, many of which are based on fundamental intensity/time relationships. These models have increased our understanding of performance but are currently limited in their application, for example due to the largely unaccounted effects of environmental factors such as, heat and altitude. In conclusion, in order to use power data as a performance biometric to be integrated in the biological passport, a number of actions must be taken to ensure accuracy of the data and better understand road cycling performance in the field. This article aims to outline considerations in the quantification of cycling performance, also presenting an alternative method (i.e., monitoring race results) to allow for determination of unusual performance improvements.

Demands of World Cup Competitions in Elite Women's Road Cycling.

PURPOSE: To describe the demand of recent World Cup (WC) races comparing top-10 (T10) and non-top-10 (N-T10) performances using power data. METHODS: Race data were collected in 1-d World Cup races during the 2012-2015 road cycling seasons. Seven female cyclists completed 49 WC races, finishing 25 times in T10 and 24 times in N-T10. Peak power (1 s) and maximal mean power (MMP) for durations of 5, 10, 20, and 30 s and 1, 2, 5, 10, 20, 30, and 60 min expressed as power to weight ratio were analyzed in T10 and N-T10. The percentage of total race time spent at different power bands was compared between T10 and N-T10 using 0.75-W·kg-1 power bands, ranging from <0.75 to >7.50 W·kg-1. The number of efforts in which the power output remained above 7.50 W·kg-1 for at least 10 s was recorded. RESULTS: MMPs were significantly higher in T10 than in N-T10, with a large effect size for durations between 10 s and 5 min. N-T10 spent more time in the 3.01- to 3.75-W·kg-1 power band when compared to T10 (P = .011); conversely, T10 spent more time in the 6.75- to 7.50- and >7.50-W·kg-1 power bands (P = .009 and .005, respectively) than N-T10. A significantly higher number of short and high-intensity efforts (≥10 s, >7.5 W·kg-1) was ridden by T10 than N-T10 (P = .002), specifically, 46 ± 20 and 30 ± 15 efforts for T10 and N-T10, respectively. CONCLUSIONS: The ability to ride at high intensity was determinant for successful road-cycling performances in WC races.

Within-Season Distribution of External Training and Racing Workload in Professional Male Road Cyclists.

PURPOSE: To describe the within-season external workloads of professional male road cyclists for optimal training prescription. METHODS: Training and racing of 4 international competitive professional male cyclists (age 24 ± 2 y, body mass 77.6 ± 1.5 kg) were monitored for 12 mo before the world team-time-trial championships. Three within-season phases leading up to the team-time-trial world championships on September 20, 2015, were defined as phase 1 (Oct-Jan), phase 2 (Feb-May), and phase 3 (June-Sept). Distance and time were compared between training and racing days and over each of the various phases. Times spent in absolute (<100, 100-300, 400-500, >500 W) and relative (0-1.9, 2.0-4.9, 5.0-7.9, >8 W/kg) power zones were also compared for the whole season and between phases 1-3. RESULTS: Total distance (3859 ± 959 vs 10911 ± 620 km) and time (240.5 ± 37.5 vs 337.5 ± 26 h) were lower (P < .01) in phase 1 than phase 2. Total distance decreased (P < .01) from phase 2 to phase 3 (10911 ± 620 vs 8411 ± 1399 km, respectively). Mean absolute (236 ± 12.1 vs 197 ± 3 W) and relative (3.1 ± 0 vs 2.5 ± 0 W/kg) power output were higher (P < .05) during racing than training, respectively. CONCLUSION: Volume and intensity differed between training and racing over each of 3 distinct within-season phases.

Superior Inhibitory Control and Resistance to Mental Fatigue in Professional Road Cyclists.

PURPOSE: Given the important role of the brain in regulating endurance performance, this comparative study sought to determine whether professional road cyclists have superior inhibitory control and resistance to mental fatigue compared to recreational road cyclists. METHODS: After preliminary testing and familiarization, eleven professional and nine recreational road cyclists visited the lab on two occasions to complete a modified incongruent colour-word Stroop task (a cognitive task requiring inhibitory control) for 30 min (mental exertion condition), or an easy cognitive task for 10 min (control condition) in a randomized, counterbalanced cross-over order. After each cognitive task, participants completed a 20-min time trial on a cycle ergometer. During the time trial, heart rate, blood lactate concentration, and rating of perceived exertion (RPE) were recorded. RESULTS: The professional cyclists completed more correct responses during the Stroop task than the recreational cyclists (705±68 vs 576±74, p = 0.001). During the time trial, the recreational cyclists produced a lower mean power output in the mental exertion condition compared to the control condition (216±33 vs 226±25 W, p = 0.014). There was no difference between conditions for the professional cyclists (323±42 vs 326±35 W, p = 0.502). Heart rate, blood lactate concentration, and RPE were not significantly different between the mental exertion and control conditions in both groups. CONCLUSION: The professional cyclists exhibited superior performance during the Stroop task which is indicative of stronger inhibitory control than the recreational cyclists. The professional cyclists also displayed a greater resistance to the negative effects of mental fatigue as demonstrated by no significant differences in perception of effort and time trial performance between the mental exertion and control conditions. These findings suggest that inhibitory control and resistance to mental fatigue may contribute to successful road cycling performance. These psychobiological characteristics may be either genetic and/or developed through the training and lifestyle of professional road cyclists.

Impact of Altitude on Power Output during Cycling Stage Racing.

PURPOSE: The purpose of this study was to quantify the effects of moderate-high altitude on power output, cadence, speed and heart rate during a multi-day cycling tour. METHODS: Power output, heart rate, speed and cadence were collected from elite male road cyclists during maximal efforts of 5, 15, 30, 60, 240 and 600 s. The efforts were completed in a laboratory power-profile assessment, and spontaneously during a cycling race simulation near sea-level and an international cycling race at moderate-high altitude. Matched data from the laboratory power-profile and the highest maximal mean power output (MMP) and corresponding speed and heart rate recorded during the cycling race simulation and cycling race at moderate-high altitude were compared using paired t-tests. Additionally, all MMP and corresponding speeds and heart rates were binned per 1000 m (<1000 m, 1000-2000, 2000-3000 and >3000 m) according to the average altitude of each ride. Mixed linear modelling was used to compare cycling performance data from each altitude bin. RESULTS: Power output was similar between the laboratory power-profile and the race simulation, however MMPs for 5-600 s and 15, 60, 240 and 600 s were lower (p ≤ 0.005) during the race at altitude compared with the laboratory power-profile and race simulation, respectively. Furthermore, peak power output and all MMPs were lower (≥ 11.7%, p ≤ 0.001) while racing >3000 m compared with rides completed near sea-level. However, speed associated with MMP 60 and 240 s was greater (p < 0.001) during racing at moderate-high altitude compared with the race simulation near sea-level. CONCLUSION: A reduction in oxygen availability as altitude increases leads to attenuation of cycling power output during competition. Decrement in cycling power output at altitude does not seem to affect speed which tended to be greater at higher altitudes.