Intrinsic factors, performance and dynamic kinematics in optimisation of cycling biomechanics

Kinematic measurements conducted during bike set-ups utilise either static or dynamic measures. There is currently limited data on reliability of static and dynamic measures nor consensus on which is the optimal method. The aim of the study was to assess the difference between static and dynamic measures of the ankle, knee, hip, shoulder and elbow. Nineteen subjects performed three separate trials of a 10min duration at a fixed workload (70% of peak power output). Static measures were taken with a standard goniometer (GM), an inclinometer (IM) and dynamic three dimensional motion capture (3DMC) using an eight camera motion capture system. Static and dynamic joint angles were compared over the three trials to assess repeatability of the measurements and differences between static and dynamic values. There was a positive correlation between GM and IM measures for all joints. Only the knee, shoulder and elbow were positively correlated between GM and 3DMC, and IM and 3DMC. Although all three instruments were reliable, 3D motion analysis utilised different landmarks for most joints and produced different means. Changes in knee flexion angle from static to dynamic are attributable to changes in the positioning of the foot. Controlling for this factor, the differences are negated. It was demonstrated that 3DMC is not interchangeable with GM and IM, and it is recommended that 3DMC develop independent reference values for bicycle configuration

The effect of handlebar height and bicycle frame length on muscular activity during cycling: a pilot study

The cycling literature is filled with reports of electromyography (EMG) analyses for a better understanding of muscle function during cycling. This research is not just limited to performance, as the cyclist’s goal may be rehabilitation, recreation, or competition, so a bicycle that meets the rider’s needs is essential for a more efficient muscular activity. Therefore, the purpose of this study was to understand the contribution of the activity of each of the following muscles: TD (trapezius descending), LD (latissimus dorsi), GM (gluteus maximus), and AD (anterior deltoid) in response to different bicycle-rider systems (handlebar height; bicycle frame length) and intensities in a bicycle equipped with a potentiometer. Surface EMG signals from muscles on the right side of the body were measured. A general linear model test was used to analyze the differences between muscle activation in the test conditions. Effect sizes were calculated using a partial Eta2 (η 2 ). The level of significance was set at 0.05. Muscle activation of different muscles differs, depending on the cycling condition (Pillai’s trace = 2.487; F (36.69) = 9.300; p < 0.001. η 2 = 0.958), mostly during low intensities. In high intensities, one specific pattern emerges, with a greater contribution of GM and TD and weaker participation of LD and AD, enhancing the cycling power output.info:eu-repo/semantics/publishedVersio

Saddle Pressures Factors in Road and Off-Road Cyclists of Both Genders: A Narrative Review

: The contact point of the pelvis with the saddle of the bicycle could generate abnormal pressure, which could lead to injuries to the perineum in cyclists. The aim of this review was to summarize in a narrative way the current literature on the saddle pressures and to present the factors that influence saddle pressures in order to prevent injury risk in road and off-road cyclists of both genders. We searched the PubMed database to identify English-language sources, using the following terms: "saddle pressures", "pressure mapping", "saddle design" AND "cycling". We also searched the bibliographies of the retrieved articles. Saddle pressures are influenced by factors such as sitting time on the bike, pedaling intensity, pedaling frequency, trunk and hand position, handlebars position, saddle design, saddle height, padded shorts, and gender. The jolts of the perineum on the saddle, especially on mountain bikes, generate intermittent pressures, which represent a risk factor for various pathologies of the urogenital system. This review highlights the importance of considering these factors that influence saddle pressures in order to prevent urogenital system injuries in cyclists

The Influence of Bicycle Geometry on Time-Trial Positioning Kinematics and Markers of Performance

Studies have previously documented how changes in cycling body kinematics are related to submaximal energetics and power output, as well as cycling performance, but few have focused specifically on how body kinematics will vary with changes in bicycle geometry. This study sought to describe kinematic changes resulting from the systematic change of several bicycle geometry variables: Trunk angle (“low” and “high” positions), seat-tube angle (76° and 80°), saddle tilt angle (0° to -10°), saddle sitting position (middle or nose), as well as two types of saddles. Methods: Well-trained cyclists were kinematically evaluated across specific combinations of geometry variables using a modified cycle ergometer at a standard relative power. Standard two dimensional sagittal-view kinematics from the left side were used to summarize a collection of kinematic variables: Trunk angle, hip angle (HA), knee angle, pelvic tilt angle, and two “composite” angles called body position and pelvic position (PP). Finally, each trial was also evaluated for frontal area (FA; m2) from stationary digital photography. Data were evaluated using repeated measures ANOVA (a=0.05) to evaluate change in kinematics between trials, as well as regression analysis to determine predictability of performance markers (HA and FA) from the collection of geometry and kinematic variables. Results: Changing trunk angle had the greatest impact on other kinematic variables, while saddle type had no influence. Regression showed that geometry variables could explain 75-85% of the variability in either HA or FA, while 78-79% of the variation in HA and 83- 84% of FA was explained by PP alone. Conclusions: The composite kinematic measure PP was generally a better predictor of both HA and FA than any combination of geometry variables. These results can serve as a starting point for understanding the interactions between bicycle geometry and body kinematics, both of which are important determinants of power generation and aerodynamic drag

Development of Bi-modal exercise bicycle for physical fitness and rehabilitation

Exercise bicycles are used for kinesiological activities; to increase general fitness, and for training for cycling events. They are also used for weight loss. The aim of this study is to produce a special exercise bike which allows for both upper and lower limbs pedalling either independently or otherwise. The manufacturing processes employed in the design involved the use of AutoCAD design suite and other production engineering processes which included material selection and acquisition, cutting, welding and drilling. The device was tested for both comfort and effectiveness for cardiac rehabilitation using the rate of heartbeat as the test parameter. A strong positive correlation was found (p&lt;0.001; r=0.962) between the two heart rate tests. An ergonomic evaluation of the bi-modal exercise bike showed 98% suitability of the seat-pedal height with the knee height of the study population and 100% suitability of the seathandle post height with the buttock-knee length of the population. In conclusion, the goal of developing a bi-modal exercise bike that permits simultaneous upper and lower limbs pedalling was realised.Keywords: exercise bicycle; cycling; ergometer; fitness; rehabilitation

Effect of cyclist’s posture on performance and interaction with the bicycle

Los ciclistas usualmente definen su postura considerando requerimientos de desempeño y confort. Sin embargo, al modificar la postura, los ciclistas deben balancear estos requerimientos ya que son competitivos entre sí. En esta investigación, se desarrolló una metodología de optimización para seleccionar la postura óptima de ciclistas considerando el mejor compromiso entre desempeño e interacción con la bicicleta. El desempeño se definió por medio del tiempo de carrera, el cual se estimó considerando la capacidad de entrega de potencia y fuerzas resistivas como la resistencia aerodinámica. La interacción con la bicicleta se caracterizó utilizando índices de presión y vibración. La metodología de optimización se implementó para seleccionar la altura de las aerobarras de cinco ciclistas en carreras de contrarreloj individuales de 20 km con diferentes inclinaciones de vía y velocidades de viento. Los resultados mostraron que la reducción de la altura de aerobarras mejoró el arrastre aerodinámico y empeoró la capacidad de entrega de potencia, y la presión y vibración en el sillín para los ciclistas medidos. Se observó que las vibraciones en el sillín constituyen la restricción más estricta para el ciclista limitando los tiempos viables de exposición, y en algunos casos, modificando los resultados de selección de postura. Se concluyó que la selección de la postura óptima debe realizarse para cada ciclista con su bicicleta y para cada condición de carrera ya que el resultado depende de estos factores.Cyclists usually define their posture according to performance and comfort requirements. However, when modifying their posture, cyclists experience a trade-off between these requirements. In this research, an optimization methodology was developed to select the optimal posture of cyclists considering the best compromise between performance and interaction with the bicycle. Performance was defined as the race time estimated from the power delivery capacity and resistive forces (e.g., aerodynamic drag). The interaction with the bicycle was characterized using pressure and vibration indices. The optimization methodology was implemented to select the aerobars’ height for five cyclists riding on 20-km individual time-trial races with various wind speed and road grade conditions. The results showed that the reduction of the aerobars’ height improved the drag area and deteriorated the power delivery capacity, pressure on the saddle, and vibrations on the saddle for all the tested cyclists. It was observed that the vibrations on the saddle imposed the greatest constraint for the cyclists, limiting the feasible exposure time and, in some cases, modifying the result obtained if the posture was selected considering only performance. It was concluded that optimal posture selection should be performed specifically for each cyclist and race condition due to the dependence of the results on these factors.Doctor en IngenieríaDoctorad

Mountain bike suspension systems and their effect on rider performance quantified through mechanical, psychological and physiological responses

Mountain bike suspension systems have been designed to improve riding performance and comfort for the cyclist. Additionally, a suspension system may reduce fatigue, energy expenditure, and enhance time trial performance. It has also been proposed, however, that using a rear suspension system on a mountain bike may be detrimental to the cyclist, causing the cyclist’s energy to be dissipated via the rear suspension system. Prior to undertaking the current research, a survey into mountain bike suspension systems was conducted to establish rider preferences, as well as their perceptions of suspension systems and riding styles. The resulting responses - that the majority of cross-country cyclists chose to ride a bike with front suspension only (a hardtail bike), despite the significant advantages that a fully suspended system has to offer – aided in the decision to address the unanswered questions that remain in this area of research. This thesis presents an investigation into mountain bike suspension systems and their effect on rider performance, quantifying the dynamic loads exerted on the bike frame and rider. Both the psychological and physiological effects of using a rear suspension system on cross-country cycling are additional considerations of this study. An initial laboratory experiment was completed to investigate the effects of rear wheel dynamics on a rough track with a high impact frequency and the consequent impact this terrain has on rider performance, comparing a full suspension and hardtail bike. Further testing was conducted on a rolling road rig, specifically designed for the purpose of the current research, which more closely represented the conditions encountered by a cyclist on a cross-country track. Testing was conducted on the rolling road rig on both a flat road and rough track, examining the interaction forces between the bike and rider. Greater resistance was experienced by cyclists when cycling on the rolling road rig compared to the roller rig which equated to the resistance encountered when cycling uphill or into a headwind. The mechanical results from both rigs were compared to dynamic simulations as a means of validating and comparing the mechanical results. An additional series of tests was carried out on an indoor track which had a similar terrain to that of the rolling road rig. This set of tests placed fewer restrictions on the cyclist as only physiological data was collected using unobtrusive portable measurement devices, and provided further results to illuminate correlations or discrepancies between the roller rig and rolling road rig experiments. The experimental rolling road rig results indicated that, when cycling on a smooth surface, the hardtail bike offered no significant physiological advantage to the cyclist; however, more power was required by the rider to pedal the fully suspended bike. This was also advocated by the simulation results. Conversely, it was highlighted that the fully suspended bike provided a significant advantage to the rider compared to the hardtail bike when cycling on extremely rough terrain on the roller rig. This was the case across the simulation results, mechanical measurements, physiological measurements and psychological measurements. Similarly, the indoor track tests indicated that cycling on a fully suspended bike provided significant advantages to a cyclist in terms of rider performance. On the contrary, the experimental rolling road rig results on a rough surface demonstrated that no significant difference was apparent between cycling on either the hardtail or fully suspended bike. This result suggests that, when a rider encounters added resistance to cycling, as is the case when cycling uphill, there is less of an advantage for a fully suspended bike even on rough terrain

The effect of alterations in effective seat tube angle on cycling performance, economy and muscle recruitment

Introduction: The bicycle seat tube angle (STA) has been used in scientific research to investigate cycling performance since the early 1980's and has led to inconclusive findings when manipulated between 69° and 82° STA configuration. Most of these studies did not clearly indicate the handlebar positioning in relation to the change in STAs. In addition, the studied duration and intensity were not a true reflection for cycling performance during races. Aim: The study aimed to compare the effect of independent alteration of effective seat tube angle (ESTA) on gross muscle activities, body kinematics and gross economy for well-trained cyclists. Methods: Ten well-trained male cyclists (mean ± SD; age 37.8 ± 3.6 years, height 178.2 ± 3.8 cm, body mass 76.9 ± 8.0 kg, VO₂ₘₐₓ 51.6 ± 5.3 ml/kg/min with 6.8 ± 2.6 years cycling experience and an average training load of 5.8 ± 2.3 hours per week for three months prior) were volunteered for this study. All cyclists were randomly assigned to either a forward or rearward saddle position after an initial preferred saddle cycling position. Each cycling position was performed at 60% of Wₚₑₐₖ for one hour with forty reflective markers placed on bony landmarks described by Vicon full body model Plug-in gait and EMG electrodes placed on the right lower limb on seven muscles. Results: The mean power output and cadences during one hour submaximal steady state cycling differed by a maximum of 0.7W and 3.5 repetitions per minute respectively between three trials. VO₂ values (P=0.95), respiratory exchange ratio (P=0.39) and heart rate (P=0.92) for the trials were not significantly different. Mean angles for each joint and gross muscle activation patterns across the three trials were not significantly different. Magnitude-based inferences statistics showed "possible beneficial effects" on knee and ankle joint kinematics when comparing the forward and rearward saddle displacement. A progressive increase in integrated EMG values was observed for gluteus maximus, biceps femoris and rectus femoris from forward to rearward position. Both vastus lateralis and vastus medialis decreased activation in forward and rearward positions as compared to preferred position. However, none of these changes were statistically significant. Conclusion: Preserving the joint kinematics of the elbow, shoulder, hip, knee and ankle joint of the cyclist when changing the saddle displacement effectively negate any change in heart rate, oxygen consumption and respiratory exchange ratio. Nonetheless, the knee and ankle joints were increased by 1° and decreased by 1.5° respectively when saddle was moved forward. Similar knee and ankle joints effects were also detected with when saddle was moved rearward, which were decreased by 3° and increased by 2° respectively. Therefore, dynamic joint angles should be controlled for future studies when manipulating saddle displacement during cycling. The seven lower limb muscles activations were not statistically significant different when using traditional statistical methods and magnitude type statistic also indicates most unlikely or very unlikely benefits for all surface EMG variables between saddle displacements. These could be due to the high degrees of variability in EMG signal during cycling. Therefore, greater numbers of participants are encouraged for future studies aimed at understanding the coordination of agonist and antagonist muscles at different ESTA. Key words: Effective seat tube angle, submaximal cycling, 3D joint kinematics, electromyography (EMG)

Effects of saddle angle on heavy intensity time trial cycling: Implications of the UCI rule 1.3.014

The UCI dictates that during sanctioned events, the saddle of the bicycle may be at angle of no more than 3° of forward rotation, so as to prevent performance advantages (Rule 1.3.014). This research investigates the effect on performance when rotating the saddle beyond the mandated angle during a laboratory 4km time trial (TT). Eleven competitive male cyclists (age 26±6 (mean±SD) yrs, height 179.2±6.7 cm, body mass 72.5±6.7 kg; V̇O2max 70.9±8.6 ml∙kg-1∙min-1) completed laboratory 4km TTs using saddle angles of 0°, 3° and 6°. Completion time and mean power were recorded, in addition to lower appendage kinematics, crank torque kinetics and cardiorespiratory responses. There were no significant changes in TT time, power output, cardiorespiratory variables or crank torque kinetics as a function of saddle angle (P>0.05). There were significant effects on minimum and maximum hip angle and the horizontal displacement of the greater trochanter (P<0.05). At 6° the maximum hip angle and forward displacement of the greater trochanter was greater compared to 0° and 3°. Minimum hip angle was greater at 6° than 3° (P<0.05). In conclusion, contravening UCI rule 1.3.014 by using a saddle angle beyond 3° does not result in performance advantages during a laboratory 4 km. However, tilting the saddle does appear to cause a forward displacement of the pelvis leading to an opening of the hip angle at the top and bottom of the pedal stroke

THE EFFECTS OF SADDLE ANGLE/INCLINATION ON LUMBOPELVIC KINEMATICS AND CARDIOMETABOLIC MEASURES

Lower back pain (LBP) is a condition which affects the lumbar portion of the spinal column that can lead to mild to extreme physical pain during seated tasks and has been shown to be prevalent in people who spend long durations sitting particularly in a slumped position or in a position with a large degree of lumbar flexion. LBP can cause regular interruptions in work and in a person’s ability to engage in exercise, and in most extreme cases warrants surgical interventions for clinical treatment. While LBP is prevalent in sedentary populations, it is also quite prevalent in cycling populations where athletes frequently train and perform in a seated position with a large degree of lumbar flexion. Bike alterations, primarily adopting a downward inclination of the anterior tip of the saddle, have been a proposed method to increase anterior pelvic tilt and decrease lumbar flexion, which may contribute to decreased incidence of LBP in cyclists. However, alterations to the fit of a bicycle have the potential to impact performance and cardiometabolic measures, and also have a potential to effect men and women differently, as bicycles were traditionally designed with the male anatomy in mind resulting in differences in the way the sexes traditionally position themselves on bicycles when they ride. Therefore, the objective of this study was to investigate the differences in torso, lumbar and pelvic kinematics differences, cardiometabolic differences (VO2 and HR), and sex-based kinematic differences of the torso, lumbar, and pelvis during a synonymous cycling task on a traditional flat (relative to the horizontal) saddle compared to a saddle angle with an anterior inclination of 12.5 degrees. We performed kinematic and cardiometabolic assessments in recreational and competitive cyclists without existing chronic LBP during an 8-minute cycling task with a fixed work rate with the flat and inclined saddle angles. A bicycle-based GXTmax (graded exercise test) was conducted in order to establish peak VO2 and peak work rate (in watts) to be used for the kinematic and cardiometabolic assessments. Two subsequent rides conducted at a work rate which corresponded with 80% of elicited peak VO2 were performed during which kinematic or cardiometabolic measures were collected. For kinematic differences motion capture of the torso, pelvis and lower limbs was conducted along with perceived rating of LBP. For cardiometabolic differences VO2 (ml·kg·min-1) and HR (bpm) were collected. For sex-based differences the kinematic data was assessed for each sex and then compared via a 2 way ANOVA analysis. The results showed that in a population of cyclists without existing chronic LBP no significant differences were exhibited as a result of the two saddle angles in lumbar, trunk or pelvic kinematics, perceived LBP, cardiometabolic measures, or kinematics between sexes. These results only directly pertain to short duration, high intensity cycling, and differences may occur if a different cycling task, particularly one of longer duration, were performed. In conclusion, a saddle inclination of 10-15 degrees does not incur any significant kinematic, cardiometabolic or sex-based differences when compared to a flat saddle angle during short duration, high intensity cycling, but further investigation on kinetics in the lumbar spine and lower limbs as a result of these saddle angles is warranted