Influence of upright versus time trial cycling position on determination of critical power and W' in trained cyclists

A comparison between novice and elite cyclists movement stability during cycling

The Lyapunov Exponent (LyE) is a non-linear technique that analyses stability, which refers to the capacity of systems to mitigate environmental perturbations. Whether elite athletes have an optimised movement stability is contentious. There has been limited research exploring the differences in movement stability using the LyE between elite and novice athletes. The purpose of this study was to compare movement stability between novice and elite male cyclists across a 4000 m bout, using the LyE. Participants completed two sessions of cycling (familiarisation and testing). Inertial measurement units were attached to the head, thorax, pelvis and left and right shanks to measure segment accelerations. The LyE was calculated using five, 100 cycle intervals across the bout. Elite cyclists had greater segment movement instability compared to novices at the head and pelvis in the longitudinal and medio-lateral direction, thorax in the medio-lateral and anterior-posterior direction and medio-lateral shanks. Both novice and elite cyclists demonstrated increased head, thorax and pelvis movement instability across the bout. This increase in instability across the bout may demonstrate the impact of fatigue on movement stability. Future research needs to now examine movement stability in the velodrome and explore the correlation between movement stability and aerodynamic drag.

Cycling position optimisation - a systematic review of the impact of positional changes on biomechanical and physiological factors in cycling

Bike positional configuration changes strongly affect cycling performance. While consensus has emerged on saddle height optimisation, there is none for the relationship between other bike positional variables and cycling performance. Accordingly, this systematic review examines the effect of all major positional variables on performance in cycling, assessing differences between cycling disciplines and sex where possible. The systematic review, conducted per PRISMA guidelines, searched databases including Embase, Web of Science, Medline, and CINAHL, screening 16,578 studies. Of these, 47 were fully analysed. Study quality assessment using the NIH tool revealed none rated "good", 5 "fair" and 33 "poor". The analysis involved 724 participants (90 female, 454 male, 180 sex unstated). Studies focused on trunk angle/upper body position, handlebar height, Q factor, foot position, saddle fore-aft/height, seat tube angle and crank length. Participant cycling disciplines were often unspecified and few papers address women cyclists specifically. Key findings were associated with changing saddle height, trunk angle and saddle fore-aft. For trunk angle, accounting for the biomechanical and physiological effects as well as aerodynamic changes is important. Saddle fore-aft affects the hip angle and trunk angle. There are no clear recommendations for crank length, handlebar height, Q factor or cleat position.

Effect of applied cadence in repeated sprint cycling on muscle characteristics

PURPOSE

This study aimed to investigate physiological responses, muscle-tendon unit properties of the quadriceps muscle, and mechanical performance after repeated sprint cycling at optimal and 70% of optimal cadence.

METHODS

Twenty recreational cyclists performed as first sprint performance cycling test and during subsequent sessions two repeated sprint cycling protocols at optimal and 70% of optimal cadence, in random order. The muscle-tendon unit outcome measures on the dominant leg included muscle thickness, fascicle length (Lf), pennation angle (θp), and stiffness for the rectus femoris (RF), vastus lateralis (VL), and vastus medialis muscle (VM) at baseline, immediately after repeated sprint cycling, and 1-h post-exercise.

RESULTS

The results showed an increase in muscle thickness and θp in RF, VL, and VM for both cadences from baseline to immediately after exercise. The Lf decreased in RF (both cadences), while stiffness decreased in RF, VL, and VM at optimal cadence, and in VL at 70% of optimal cadence from baseline to immediately after exercise.

CONCLUSION

The present study revealed that the alterations in muscle characteristics were more marked after repeated sprint cycling at optimal cadence compared with a lower cadence most likely as a result of higher load on the muscle-tendon unit at optimal cadence.

The Effect of Bicycle Saddle Widths on Saddle Pressure in Female Cyclists

Choosing an unsuitable bicycle saddle increases the saddle pressure and discomfort during cycling. Women contract sports injuries more easily than men during cycling owing to their anatomy. To investigate the effect of saddle widths on the saddle pressure in female cyclists. Ten healthy women with an average age of 20.7 ± 1.3 years, height of 162 ± and 5.9 cm, weight of 56.1 ± 7.5 kg, and a sciatic bone width of 15.5 ± 1.4 cm were recruited for this study. The distributions of saddle pressure for four different saddle widths (i.e., narrow, moderate, wide, and self-chosen) were recorded using a saddle pressure mat. Participants were instructed to pedal steadily with a frequency of 90 RPM and a load of 150 watts. Thirty seconds of riding data was randomly retrieved for analysis. The trials were conducted with a counter-balanced design to minimize random errors. One-way repeated measures ANOVA was used to compare the saddle pressure of different saddle widths, and the significance level was set at α = 0.05. When wide saddles were used, the maximum and average pressure on the right surface of the posterior ischium were lower than those with narrow (p = 0.001, p = 0.012) and moderate (p = 0.016, p = 0.019) saddles. The area of pressure on the pubic bone was smaller when using a wide saddle than when using narrow (p = 0.005) and moderate (p = 0.018) saddles, and the area of pressure on the right posterior sciatic bone was larger under the wide saddle than under the narrow (p = 0.017) and moderate (p = 0.036) saddles. The average force was greater with the moderate saddle than with the wide (p = 0.008) and self-chosen (p = 0.025) saddles. Using a saddle with a width that is longer than the width of the cyclist's ischium by 1 cm can effectively improve the distribution of saddle pressure during riding, while providing better comfort.

Analysis of Movement Variability in Cycling: An Exploratory Study

The purpose of this study was to determine the test-retest repeatability of Blue Trident inertial measurement units (IMUs) and VICON Nexus kinematic modelling in analysing the Lyapunov Exponent (LyE) during a maximal effort 4000 m cycling bout in different body segments/joints. An additional aim was to determine if changes in the LyE existed across a trial. Twelve novice cyclists completed four sessions of cycling; one was a familiarisation session to determine a bike fit and become better accustomed to the time trial position and pacing of a 4000 m effort. IMUs were attached to the head, thorax, pelvis and left and right shanks to analyse segment accelerations, respectively, and reflective markers were attached to the participant to analyse neck, thorax, pelvis, hip, knee and ankle segment/joint angular kinematics, respectively. Both the IMU and VICON Nexus test-retest repeatability ranged from poor to excellent at the different sites. In each session, the head and thorax IMU acceleration LyE increased across the bout, whilst pelvic and shank acceleration remained consistent. Differences across sessions were evident in VICON Nexus segment/joint angular kinematics, but no consistent trend existed. The improved reliability and the ability to identify a consistent trend in performance, combined with their improved portability and reduced cost, advocate for the use of IMUs in analysing movement variability in cycling. However, additional research is required to determine the applicability of analysing movement variability during cycling.

Effects of Flat and Uphill Cycling on the Power-duration Relationship

The purpose of this study was to investigate the effects of flat and uphill cycling on critical power and the work available above critical power. Thirteen well-trained endurance athletes performed three prediction trials of 10-, 4- and 1-min in both flat (0.6%) and uphill (9.8%) cycling conditions on two separate days. Critical power and the work available above critical power were estimated using various mathematical models. The best individual fit was used for further statistical analyses. Paired t-tests and Bland-Altman plots with 95% limits of agreement were applied to compare power output and parameter estimates between cycling conditions. Power output during the 10- and 4-min prediction trial and power output at critical power were not significantly affected by test conditions (all at p>0.05), but the limits of agreement between flat and uphill cycling power output and critical power estimates are too large to consider both conditions as equivalent. However, power output during the 1-min prediction trial and the work available above critical power were significantly higher during uphill compared to flat cycling (p<0.05). The results of this investigation indicate that gradient affects cycling time-trial performance, power output at critical power, and the amount of work available above critical power.

Power profiling and the power-duration relationship in cycling: a narrative review

Emerging trends in technological innovations, data analysis and practical applications have facilitated the measurement of cycling power output in the field, leading to improvements in training prescription, performance testing and race analysis. This review aimed to critically reflect on power profiling strategies in association with the power-duration relationship in cycling, to provide an updated view for applied researchers and practitioners. The authors elaborate on measuring power output followed by an outline of the methodological approaches to power profiling. Moreover, the deriving a power-duration relationship section presents existing concepts of power-duration models alongside exercise intensity domains. Combining laboratory and field testing discusses how traditional laboratory and field testing can be combined to inform and individualize the power profiling approach. Deriving the parameters of power-duration modelling suggests how these measures can be obtained from laboratory and field testing, including criteria for ensuring a high ecological validity (e.g. rider specialization, race demands). It is recommended that field testing should always be conducted in accordance with pre-established guidelines from the existing literature (e.g. set number of prediction trials, inter-trial recovery, road gradient and data analysis). It is also recommended to avoid single effort prediction trials, such as functional threshold power. Power-duration parameter estimates can be derived from the 2 parameter linear or non-linear critical power model: P(t) = W'/t + CP (W'-work capacity above CP; t-time). Structured field testing should be included to obtain an accurate fingerprint of a cyclist's power profile.

Maintaining Power Output with Accumulating Levels of Work Done Is a Key Determinant for Success in Professional Cycling

INTRODUCTION

This study aimed to investigate if performance measures are related to success in professional cycling and to highlight the influence of prior work done on these performance measures and success.

METHODS

Power output data from 26 professional cyclists, in a total of 85 seasons, collected between 2012 and 2019, were analyzed. The cyclists were classified as "climber" or "sprinter" and into category 1 (CAT.1; ≥400 PCSpoints (successful)) and CAT.2 (<400 PCSpoints (less successful)), based on the number of procyclingstats-points (PCSpoints) collected for that particular season. Maximal mean power outputs (MMP) for 20 min, 5 min, 1 min, and 10 s relative to body weight for every season were determined. To investigate the influence of prior work done on these MMP values, six different levels of completed work done were determined, which are based on the amount of completed kilojoules per kilogram (0, 10, 20, 30, 40, and 50 kJ·kg-1). Subsequently, the decline in MMP for each duration (if any) after each level of completed work done was evaluated.

RESULTS

Mixed model revealed that prior work done affects the performance of climbers and sprinters negatively. However, CAT.1 climbers have a smaller decline in 20- and 5-min MMP after high amounts of work done compared with CAT.2 climbers. Similarly, CAT.1 sprinters have a smaller decline in 10-s and 1-min MMP after high amounts of work done compared with CAT.2 sprinters.

CONCLUSIONS

It seems that the ability to maintain high MMP (corresponding with the specialization of a cyclist) after high amounts of work done (i.e., fatigue) is an important parameter for success in professional cyclists. These findings suggest that assessing changes in MMP after different workloads might be highly relevant in professional cycling.

Changes in the Trunk and Lower Extremity Kinematics Due to Fatigue Can Predispose to Chronic Injuries in Cycling

Kinematic analysis of the cycling position is a determining factor in injury prevention and optimal performance. Fatigue caused by high volume training can alter the kinematics of the lower body and spinal structures, thus increasing the risk of chronic injury. However, very few studies have established relationships between fatigue and postural change, being these in 2D analysis or incremental intensity protocols. Therefore, this study aimed to perform a 3D kinematic analysis of pedaling technique in a stable power fatigue protocol 23 amateur cyclists (28.3 ± 8.4 years) participated in this study. For this purpose, 3D kinematics in hip, knee, ankle, and lumbar joints, and thorax and pelvis were collected at three separate times during the protocol. Kinematic differences at the beginning, middle, and end of the protocol were analyzed for all joints using one-dimensional statistical parametric mapping. Significant differences (p < 0.05) were found in all the joints studied, but not all of them occur in the same planes or the same phase of the cycle. Some of the changes produced, such as greater lumbar and thoracic flexion, greater thoracic and pelvic tilt, or greater hip adduction, could lead to chronic knee and lumbar injuries. Therefore, bike fitting protocols should be carried out in fatigue situations to detect risk factor situations.

The Effect of Upper-Body Positioning on the Aerodynamic–Physiological Economy of Time-Trial Cycling

Purpose: Cycling time trials (TTs) are characterized by riders’ adopting aerodynamic positions to lessen the impact of aerodynamic drag on velocity. The optimal performance requirements for TTs likely exist on a continuum of rider aerodynamics versus physiological optimization, yet there is little empirical evidence to inform riders and coaches. The aim of the present study was to investigate the relationship between aerodynamic optimization, energy expenditure, heat production, and performance. Methods: Eleven trained cyclists completed 5 submaximal exercise tests followed by a TT. Trials were completed at hip angles of 12° (more horizontal), 16°, 20°, 24° (more vertical), and their self-selected control position. Results: The largest decrease in power output at anaerobic threshold compared with control occurred at 12° (−16 [20] W, P = .03; effect size [ES] = 0.8). There was a linear relationship between upper-body position and heat production (R2 = .414, P = .04) but no change in mean body temperature, suggesting that, as upper-body position and hip angle increase, convective and evaporative cooling also rise. The highest aerodynamic–physiological economy occurred at 12° (384 [53] W·CdA−1·L−1·min−1, ES = 0.4), and the lowest occurred at 24° (338 [28] W·CdA−1·L−1·min−1, ES = 0.7), versus control (367 [41] W·CdA−1·L−1·min−1). Conclusion: These data suggest that the physiological cost of reducing hip angle is outweighed by the aerodynamic benefit and that riders should favor aerodynamic optimization for shorter TT events. The impact on thermoregulation and performance in the field requires further investigation.

Performance variables associated with bicycle configuration and flexibility

OBJECTIVES

Cycling races are often won by the smallest of margins. Research has focused on optimal saddle height for performance, however the relationship between freely chosen bicycle configuration and individual factors such as anthropometrics and flexibility have not yet been investigated adequately. The aim of this study was to determine if an association between power production, bicycle configuration and flexibility exists.

DESIGN

Experimental, quantitative study.

METHODS

Fifty male cyclists were recruited for the study. Individual anthropometrics, flexibility and individual bicycle configuration were recorded before the participants performed a peak power output and peak oxygen consumption test to determine their VO_2max.

RESULTS

There was a significant correlation between performance and hamstring flexibility, handlebar drop, saddle setback and ankle plantarflexion. An increased lumbar flexibility demonstrated an inverse relationship with relative VO_2max. A more anteriorly rotated pelvis correlated with improved hamstring flexibility, hip flexion angle and an increased handlebar drop.

SIGNIFICANCE

The results from this study have clinical implications for bike fitters and cyclists. Greater saddle setback and lower handlebar height may increase peak power output. Improving a cyclist's flexibility and ability to adopt an anteriorly rotated pelvis and lower handlebar height may increase the force generated in the push phase of the pedal stroke and thus improve cycling performance.

Vibrotactile feedback for correcting aerodynamic position of a cyclist

Guidance to maintain an optimal aerodynamic position is currently unavailable during cycling. This study used real-time vibrotactile feedback to guide cyclists to a reference position with minimal projected frontal area as an indicator of aerodynamic drag, by optimizing torso, shoulder, head and elbow position without compromising comfort when sitting still on the bike. The difference in recapturing the aerodynamic reference position during cycling after predefined deviations from the reference position at different intensities was analysed for 14 participants between three interventions, consisting of 1) vibrotactile feedback with a margin of error of 1.5% above the calibrated reference projected frontal area, 2) vibrotactile feedback with a margin of 3%, and 3) no feedback. The reference position is significantly more accurately achieved using vibrotactile feedback compared to no feedback (p < 0.001), but there is no significant difference between the 1.5% and 3% margin (p = 0.11) in terms of relative projected frontal area during cycling compared to the calibrated reference position (1.5% margin -0.46 ± 1.76%, 3% margin -0.01 ± 2.01%, no feedback 2.59 ± 3.29%). The results demonstrate that vibrotactile feedback can have an added value in assisting and correcting cyclists in recapturing their aerodynamic reference position.