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1.
The aim of this study was to determine the response of cyclists to manipulations of cadence and power output in terms of force application and plantar pressure distribution. Two groups of cyclists, 17 recreational and 12 competitive, rode at three nominal cadences (60, 80, 100 rev min -1 ) and four power outputs (100, 200, 300, 400 W) while simultaneous force and in-shoe pressure data were collected. Two piezoelectric triaxial force transducers mounted in the right pedal measured components of the pedal force and orientation, and a discrete transducer system with 12 transducers recorded the in-shoe pressures. Force application was characterized by calculating peak resultant and peak effective pedal forces and positive and negative impulses. In-shoe pressures were analysed as peak pressures and as the percent relative load. The force data showed no significant group effect but there was a cadence and power main effect. The impulse data showed a significant three-way interaction. Increased cadence resulted in a decreased positive impulse, while increased power output resulted in an increased impulse. The competitive group produced less positive impulse but the difference became less at higher cadences. Few between-group differences were found in pressure, notable only in the pressure under the first metatarsal region. This showed a consistent pattern of in-shoe pressure distribution, where the primary loading structures were the first metatarsal and hallux. There was no indication that pressure at specific sites influenced the pedal force application. The absence of group differences indicated that pressure distribution was not the result of training, but reflected the intrinsic relationship between the foot, the shoe and the pedal.  相似文献   

2.
The aim of this study was to determine the response of cyclists to manipulations of cadence and power output in terms of force application and plantar pressure distribution. Two groups of cyclists, 17 recreational and 12 competitive, rode at three nominal cadences (60, 80, 100 rev x min(-1)) and four power outputs (100, 200, 300, 400 W) while simultaneous force and in-shoe pressure data were collected. Two piezoelectric triaxial force transducers mounted in the right pedal measured components of the pedal force and orientation, and a discrete transducer system with 12 transducers recorded the in-shoe pressures. Force application was characterized by calculating peak resultant and peak effective pedal forces and positive and negative impulses. In-shoe pressures were analysed as peak pressures and as the percent relative load. The force data showed no significant group effect but there was a cadence and power main effect. The impulse data showed a significant three-way interaction. Increased cadence resulted in a decreased positive impulse, while increased power output resulted in an increased impulse. The competitive group produced less positive impulse but the difference became less at higher cadences. Few between-group differences were found in pressure, notable only in the pressure under the first metatarsal region. This showed a consistent pattern of in-shoe pressure distribution, where the primary loading structures were the first metatarsal and hallux. There was no indication that pressure at specific sites influenced the pedal force application. The absence of group differences indicated that pressure distribution was not the result of training, but reflected the intrinsic relationship between the foot, the shoe and the pedal.  相似文献   

3.
The aim of this study was to determine whether cyclists modify the pattern of force application to become more effective during a prolonged ride to exhaustion. Twelve competitive male cyclists completed a steady-rate exercise ride to exhaustion at 80% of their maximum power output at 90 rev x min(-1) on a cycle ergometer. Pedal force, pedal and crank angle data were collected from an instrumented bicycle for three pedalling cycles at the end of the first and final minutes of the exercise test with simultaneous video recording of the lower limbs. Kinematic and force data were combined to compute hip, knee and ankle joint moments. There were changes in the pattern of force application, joint kinematics and joint moments of force. Comparison of the first minute and the final minute ride revealed significantly increased peak effective force (340 +/- 65.0 and 377 +/- 74.8 N for the first and final minute, respectively; F1,11 = 7.44, P = 0.02), increased positive (28.4 +/- 4.5 and 30.5 +/- 4.8 N x s for the first and final minute, respectively; F1,11 = 7.80, P = 0.02) and negative angular impulses (-1.5 +/- 1.6 and -2.4 +/- 1.5 N x s for the first and final minute, respectively; F1,11 = 4.50, P = 0.06). Contrary to our initial assumptions, it would appear that riders became less effective during the recovery phase, which increased the demand for forces during the propulsive phase. Training the pattern of force application to improve effectiveness may be a useful strategy to prolong an endurance ride.  相似文献   

4.
A system was developed for measuring and analyzing the forces placed on a bicycle pedal during operation of a stationary ergometer. Forces are measured in the plane parallel to the ergometer in directions normal and tangential to the surface of the pedals, encompassing the plane of propulsive forces. The pedals are designed to be structurally and functionally equivalent to standard clipless pedals. The stock pedal spindle and bearing assembly was replaced with a new spindle that was instrumented with two Wheatstone bridges of foil strain gauges. The bearings were relocated to the crank-arm/pedal-spindle interface. The original pedal body was then pinned to the new spindle. Additionally, the pedals were instrumented with optical encoders to measure the pedal angle relative to the crank arm. An optical encoder was also mounted near the bottom bracket to measure crank-arm angle. Signals were transmitted via a cable tethered to the cyclist’s leg from the pedals to an instrumented chassis, where the strain gauge signals were conditioned and the digital optical encoder signals converted to analogue signals. From the instrumented chassis, seven signals are ready for standard analogue data collection. Data collected from this new system has proved to be both comparable with previously published literature and accurate when compared with expected power output values.  相似文献   

5.
In this study, we evaluated the effects of a novel pedal design, characterized by a downward and forward shift of the cleat fixing platform relative to the pedal axle, on maximal power output and mechanical efficiency in 22 well-trained cyclists. Maximal power output was measured during a series of short (5-s) intermittent sprints on an isokinetic cycle ergometer at cadences from 40 to 120 rev min(-1). Mechanical efficiency was evaluated during a submaximal incremental exercise test on a bicycle ergometer using continuous VO(2) and VCO(2) measurement. Similar tests with conventional pedals and the novel pedals, which were mounted on the individual racing bike of the participant, were randomized. Maximal power was greater with novel pedals than with conventional pedals (between 6.0%, s(x) = 1.5 at 40 rev min(-1) and 1.8%, s(x) = 0.7 at 120 rev min(-1); P = 0.01). Torque production between crank angles of 60 degrees and 150 degrees was higher with novel pedals than with conventional pedals (P = 0.004). The novel pedal design did not affect whole-body VO(2) or VCO(2). Mechanical efficiency was greater with novel pedals than with conventional pedals (27.2%, s(x) = 0.9 and 25.1%, s(x) = 0.9% respectively; P = 0.047; effect size = 0.9). In conclusion, the novel pedals can increase maximal power output and mechanical efficiency in well-trained cyclists.  相似文献   

6.
Although the link between sagittal plane motion and exercise intensity has been highlighted, no study assessed if different workloads lead to changes in three-dimensional cycling kinematics. This study compared three-dimensional joint and segment kinematics between competitive and recreational road cyclists across different workloads. Twenty-four road male cyclists (12 competitive and 12 recreational) underwent an incremental workload test to determine aerobic peak power output. In a following session, cyclists performed four trials at sub-maximal workloads (65, 75, 85 and 95% of their aerobic peak power output) at 90?rpm of pedalling cadence. Mean hip adduction, thigh rotation, shank rotation, pelvis inclination (latero-lateral and anterior–posterior), spine inclination and rotation were computed at the power section of the crank cycle (12 o'clock to 6 o'clock crank positions) using three-dimensional kinematics. Greater lateral spine inclination (p?p?p?相似文献   

7.
Abstract

In this study, we evaluated the effects of a novel pedal design, characterized by a downward and forward shift of the cleat fixing platform relative to the pedal axle, on maximal power output and mechanical efficiency in 22 well-trained cyclists. Maximal power output was measured during a series of short (5-s) intermittent sprints on an isokinetic cycle ergometer at cadences from 40 to 120 rev · min?1. Mechanical efficiency was evaluated during a submaximal incremental exercise test on a bicycle ergometer using continuous [Vdot]O2 and [Vdot]CO2 measurement. Similar tests with conventional pedals and the novel pedals, which were mounted on the individual racing bike of the participant, were randomized. Maximal power was greater with novel pedals than with conventional pedals (between 6.0%, sx  = 1.5 at 40 rev · min?1 and 1.8%, sx  = 0.7 at 120 rev · min?1; P = 0.01). Torque production between crank angles of 60° and 150° was higher with novel pedals than with conventional pedals (P = 0.004). The novel pedal design did not affect whole-body [Vdot]O2 or [Vdot]CO2. Mechanical efficiency was greater with novel pedals than with conventional pedals (27.2%, sx  = 0.9 and 25.1%, sx  = 0.9% respectively; P = 0.047; effect size = 0.9). In conclusion, the novel pedals can increase maximal power output and mechanical efficiency in well-trained cyclists.  相似文献   

8.
The cadence that maximises power output developed at the crank by an individual cyclist is conventionally determined using a laboratory test. The purpose of this study was two-fold: (i) to show that such a cadence, which we call the optimal cadence, can be determined using power output, heart-rate, and cadence measured in the field and (ii) to describe methodology to do so. For an individual cyclist's sessions, power output is related to cadence and the elicited heart-rate using a non-linear regression model. Optimal cadences are found for two riders (83 and 70 revolutions per minute, respectively); these cadences are similar to the riders’ preferred cadences (82–92?rpm and 65–75?rpm). Power output reduces by approximately 6% for cadences 20?rpm above or below optimum. Our methodology can be used by a rider to determine an optimal cadence without laboratory testing intervention: the rider will need to collect power output, heart-rate, and cadence measurements from training and racing sessions over an extended period (>6 months); ride at a range of cadences within those sessions; and calculate his/her optimal cadence using the methodology described or a software tool that implements it.  相似文献   

9.
Effective force and economy of triathletes and cyclists   总被引：1，自引：0，他引：1  
The effective force applied on the crank, the index of pedalling effectiveness, and the economy of movement at 60, 75, 90, and 105 rev/min cadences were examined in nine cyclists and eight triathletes. Tests were performed on two days. Maximal oxygen uptake was measured and the second ventilatory threshold was estimated on day 1 using a stationary bicycle. On day 2, the four different cadences were tested at about 5% below the second ventilatory threshold. A strain gauge instrumented clip-less pedal mounted on the bicycle enabled us to measure the normal and tangential forces exerted on the pedal, while the pedal and crank angles were monitored with the aid of a video system. Based on this information, the effective force and the index of pedalling effectiveness were calculated. Cyclists produced significantly more effective force and a higher index of pedalling effectiveness at 60 and 75 rev/min and were significantly more economic at all cadences than triathletes. The significant and positive correlation between effective force and economy at all cadences suggests that improvement of the effective force would reflect on economy.  相似文献   

10.
The effective force applied on the crank, the index of pedalling effectiveness, and the economy of movement at 60, 75, 90, and 105 rev/min cadences were examined in nine cyclists and eight triathletes. Tests were performed on two days. Maximal oxygen uptake was measured and the second ventilatory threshold was estimated on day 1 using a stationary bicycle. On day 2, the four different cadences were tested at about 5% below the second ventilatory threshold. A strain gauge instrumented clip-less pedal mounted on the bicycle enabled us to measure the normal and tangential forces exerted on the pedal, while the pedal and crank angles were monitored with the aid of a video system. Based on this information, the effective force and the index of pedalling effectiveness were calculated. Cyclists produced significantly more effective force and a higher index of pedalling effectiveness at 60 and 75 rev/min and were significantly more economic at all cadences than triathletes. The significant and positive correlation between effective force and economy at all cadences suggests that improvement of the effective force would reflect on economy.  相似文献   

11.
利用SRM功率车以及安装在功率车上的测力系统(Powertec-System)研究不同踏蹬频率下场地自行车运动员一个踏蹬周期内作用于曲柄的切向踏蹬力特征。以8名自行车运动员为研究对象,在SRM功率车上进行10min、90rpm、120w的准备活动后,进行阻力负荷为500watt的骑行,踏蹬频率分别为100、120、130、140rpm,顺序随机选择,骑行稳定后,采集连续5s的踏蹬力数据。结果表明,随着踏蹬频率的提高,作用在左、右两侧曲柄的切向踏蹬力分量的正均值、均值、最大值减小,两侧切向踏蹬力分量之和的均值及峰值也减小(p<0.01);左、右侧正切向踏蹬力分量的起止位置、最值位置、双侧切向踏蹬力分量之和的峰值位置均随着踏蹬频率的增大而提前(p<0.01);在踏蹬周期的下半段,踏蹬频率越高,切向踏蹬力曲线越低,在踏蹬周期的上半段,踏蹬频率越高,切向踏蹬力曲线越高。  相似文献   

12.
Besides its regulation by Union Cycliste Internationale, the evidence relating saddle setback to pedalling performance remains inconclusive. This study investigates the influence of saddle setback on pedalling effectiveness through two indexes: an index of pedalling force effectiveness and an index of pedalling work effectiveness. Eleven cyclists were assessed six saddle setback conditions while pedalling at a steady power output of 200 W and cadence of 90 rpm. A force sensor was integrated within the seat post to compute the centre of pressure on the saddle. From instrumented pedals, an index of force effectiveness (ratio between the force directed perpendicular to the crank arm and the total force applied to the pedal) and an index of work effectiveness (based on the minimisation of negative crank work) were calculated. In comparison with a forward position, sitting backward significantly decreased 5% cumulative total work, increased index of work effectiveness (84.2 ± 3.7 vs. 82.0 ± 4.7%), and increased index of force effectiveness (41.7 ± 2.9 vs. 39.9 ± 3.7 and 36.9 ± 0.7%). Thus, while it was previously reported that sitting more forward favours maximal power, this study demonstrates that it also leads to a decreased effectiveness in steady-state pedalling.  相似文献   

13.
Cyclists regularly change from a seated to a standing position when the gradient increases during uphill cycling. The aim of this study was to analyse the physiological and biomechanical responses between seated and standing positions during distance-based uphill time trials in elite cyclists. Thirteen elite cyclists completed two testing sessions that included an incremental-specific cycling test on a cycle ergometer to determine VO2max and three distance-based uphill time trials in the field to determine physiological and biomechanical variables. The change from seated to standing position did not influence physiological variables. However, power output was increased by 12.6% in standing position when compared with seated position, whereas speed was similar between the two positions. That involved a significant increase in mechanical cost and tangential force (Ftang) on the pedal (+19% and +22.4%, respectively) and a decrease (?8%) in the pedalling cadence. Additionally, cyclists spent 22.4% of their time in the standing position during the climbing time trials. Our findings showed that cyclists alternated between seated and standing positions in order to maintain a constant speed by adjusting the balance between pedalling cadence and Ftang.  相似文献   

14.
Abstract

Knee functional disorders are one of the most common lower extremity non-traumatic injuries reported by cyclists. Incorrect bicycle configuration may predispose cyclist to injury but the evidence of an effect of saddle setback on knee pain remains inconclusive. The aim of this study was to determine the effect of saddle setback on knee joint forces during pedalling using a musculoskeletal modelling approach. Ten cyclists were assessed under three saddle setback conditions (range of changes in saddle position ~6 cm) while pedalling at a steady power output of 200 W and cadence of 90 rpm. A cycling musculoskeletal model was developed and knee joint forces were estimated using an inverse dynamics method associated with a static optimisation procedure. Our results indicate that moving the saddle forwards was not associated with an increase of patellofemoral joint forces. On the contrary, the tibiofemoral mean and peak compression force were 14 and 15% higher in the Backward than in the Forward condition, respectively. The peak compression force was related to neither pedal force nor quadriceps muscle force but coincided with the eccentric contraction of knee flexor muscles. These findings should benefit bike fitting practitioners and coaches in the design of specific training/rehabilitation protocols.  相似文献   

15.
Body position is known to alter power production and affect cycling performance. The aim of this study was to compare mechanical power output in two riding positions, and to calculate the effects on critical power (CP) and W′ estimates. Seven trained cyclists completed three peak power output efforts and three fixed-duration trial (3-, 5- and 12-min) riding with their hands on the brake lever hoods (BLH), or in a time trial position (TTP). A repeated-measures analysis of variance showed that mean power output during the 5-min trial was significantly different between BLH and TTP positions, resulting in a significantly lower estimate of CP, but not W′, for the TTP trial. In addition, TTP decreased the performance during each trial and increased the percentage difference between BLH and TTP with greater trial duration. There were no differences in pedal cadence or heart rate during the 3-min trial; however, TTP results for the 12-min trial showed a significant fall in pedal cadence and a significant rise in heart rate. The findings suggest that cycling position affects power output and influences consequent CP values. Therefore, cyclists and coaches should consider the cycling position used when calculating CP.  相似文献   

16.
The purpose of this study was to analyze pedaling cadence, pedal forces, and muscle activation of triathletes during cycling to exhaustion. Fourteen triathletes were assessed at the power output level relative to their maximal oxygen uptake (355 +/- 23 W). Cadence, pedal forces, and muscle activation were analyzed during start, middle, and end test stages. Normal and tangential forces increased from the start to the end of the test (-288 +/- 33 to -352 +/- 42 N and -79 +/- 45 to -124 +/- 68 N, respectively) accompanied by a decrease in cadence (96 +/- 5 to 86 +/- 6 rpm). Muscle activation increased from the start to the middle and the end in the gluteus maximus (27 +/- 5.5% and 76 +/- 9.3%) and in the vastus lateralis (13 +/- 3.5% and 27 +/- 4.4%), similar increase was observed from the start to the end in the rectus femoris and the vastus medialis (50 +/- 9.3% and 20 +/- 5.7%, respectively). Greater normal force along with enhanced activation of knee and hip extensor muscles is linked with fatigue and declines in cadence of triathletes during cycling to exhaustion.  相似文献   

17.
Abstract

The effects of saddle height on pedal forces and joint kinetics (e.g. mechanical work) are unclear. Therefore, we assessed the effects of saddle height on pedal forces, joint mechanical work and kinematics in 12 cyclists and 12 triathletes. Four sub-maximal 2-min cycling trials (3.4 W/kg and 90 rpm) were conducted using preferred, low and high saddle heights (±10° knee flexion at 6 o'clock crank position from the individual preferred height) and an advocated optimal saddle height (25° knee flexion at 6 o'clock crank position). Right pedal forces and lower limb kinematics were compared using effect sizes (ES). Increases in saddle height (5% of preferred height, ES=4.6) resulted in large increases in index of effectiveness (7%, ES=1.2) at the optimal compared to the preferred saddle height for cyclists. Greater knee (11–15%, ES=1.6) and smaller hip (6–8%, ES=1.7) angles were observed at the low (cyclists and triathletes) and preferred (triathletes only) saddle heights compared to high and optimal saddle heights. Smaller hip angle (5%, ES=1.0) and greater hip range of motion (9%, ES=1.0) were observed at the preferred saddle height for triathletes compared to cyclists. Changes in saddle height up to 5% of preferred saddle height for cyclists and 7% for triathletes affected hip and knee angles but not joint mechanical work. Cyclists and triathletes would opt for saddle heights <5 and <7%, respectively, within a range of their existing saddle height.  相似文献   

18.
The speed attained by a track cyclist is strongly influenced by aerodynamic drag, being the major retarding force in track events of more than 200 m. The aims of this study were to determine the effect of changes in shoulder and torso angles on the aerodynamic drag and power output of a track cyclist. The drag of three competitive track cyclists was measured in a wind tunnel at 40 kph. Changes in shoulder and torso angles were made using a custom adjustable handlebar setup. The power output was measured for each position using an SRM Power Meter. The power required by each athlete to maintain a specific speed in each position was calculated, which enabled the surplus power in each position to be determined. The results showed that torso angle influenced the drag area and shoulder angle influenced the power output, and that a low torso angle and middle shoulder angle optimised the surplus power. However, the lowest possible torso angle was not always the best position. Although differences between individual riders was seen, there was a strong correlation between torso angle and drag area.  相似文献   

19.
In this holistic review of cycling science, the objectives are: (1) to identify the various human and environmental factors that influence cycling power output and velocity; (2) to discuss, with the aid of a schematic model, the often complex interrelationships between these factors; and (3) to suggest future directions for research to help clarify how cycling performance can be optimized, given different race disciplines, environments and riders. Most successful cyclists, irrespective of the race discipline, have a high maximal aerobic power output measured from an incremental test, and an ability to work at relatively high power outputs for long periods. The relationship between these characteristics and inherent physiological factors such as muscle capilliarization and muscle fibre type is complicated by inter-individual differences in selecting cadence for different race conditions. More research is needed on high-class professional riders, since they probably represent the pinnacle of natural selection for, and physiological adaptation to, endurance exercise. Recent advances in mathematical modelling and bicycle-mounted strain gauges, which can measure power directly in races, are starting to help unravel the interrelationships between the various resistive forces on the bicycle (e.g. air and rolling resistance, gravity). Interventions on rider position to optimize aerodynamics should also consider the impact on power output of the rider. All-terrain bicycle (ATB) racing is a neglected discipline in terms of the characterization of power outputs in race conditions and the modelling of the effects of the different design of bicycle frame and components on the magnitude of resistive forces. A direct application of mathematical models of cycling velocity has been in identifying optimal pacing strategies for different race conditions. Such data should, nevertheless, be considered alongside physiological optimization of power output in a race. An even distribution of power output is both physiologically and biophysically optimal for longer ( > 4 km) time-trials held in conditions of unvarying wind and gradient. For shorter races (e.g. a 1 km time-trial), an 'all out' effort from the start is advised to 'save' time during the initial phase that contributes most to total race time and to optimize the contribution of kinetic energy to race velocity. From a biophysical standpoint, the optimum pacing strategy for road time-trials may involve increasing power in headwinds and uphill sections and decreasing power in tailwinds and when travelling downhill. More research, using models and direct power measurement, is needed to elucidate fully how much such a pacing strategy might save time in a real race and how much a variable power output can be tolerated by a rider. The cyclist's diet is a multifactorial issue in itself and many researchers have tried to examine aspects of cycling nutrition (e.g. timing, amount, composition) in isolation. Only recently have researchers attempted to analyse interrelationships between dietary factors (e.g. the link between pre-race and in-race dietary effects on performance). The thermal environment is a mediating factor in choice of diet, since there may be competing interests of replacing lost fluid and depleted glycogen during and after a race. Given the prevalence of stage racing in professional cycling, more research into the influence of nutrition on repeated bouts of exercise performance and training is required.  相似文献   

20.
Limited evidence showed that higher workload increases knee forces without effects from changes in pedalling cadence. This study assessed the effects of workload and cadence on patellofemoral and tibiofemoral joint forces using a new model. Right pedal force and lower limb joint kinematics were acquired for 12 competitive cyclists at two levels of workload (maximal and second ventilatory threshold) at 90 and 70 rpm of pedalling cadence. The maximal workload showed 18% larger peak patellofemoral compressive force PFC (large effect size, ES) than the second ventilatory threshold workload (90 rpm). In the meantime, the 90-rpm second ventilatory threshold was followed by a 29% smaller PFC force (large ES) than the 70-rpm condition. Normal and anterior tibiofemoral compressive forces were not largely affected by changes in workload or pedalling cadence. Compared to those of previous studies, knee forces normalized by workload were larger for patellofemoral (mean = 19 N/J; difference to other studies = 20–45%), tibiofemoral compressive (7.4 N/J; 20–572%), and tibiofemoral anterior (0.5 N/J; 60–200%) forces. Differences in model design and testing conditions (such as workload and pedalling cadence) may affect prediction of knee joint forces.  相似文献   

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