Seated Cycling Research Articles

Joint contact forces during semi-recumbent seated cycling

Semi-recumbent cycling performed from a wheelchair is a popular rehabilitation exercise following spinal cord injury (SCI) and is often paired with functional electrical stimulation. However, biomechanical assessment of this cycling modality is lacking, even in unimpaired populations, hindering the development of personalised and safe rehabilitation programs for those with SCI. This study developed a computational pipeline to determine lower limb kinematics, kinetics, and joint contact forces (JCF) in 11 unimpaired participants during voluntary semi-recumbent cycling using a rehabilitation ergometer. Two cadences (40 and 60 revolutions per minute) and three crank powers (15 W, 30 W, and 45 W) were assessed. A rigid body model of a rehabilitation ergometer was combined with a calibrated electromyogram-informed neuromusculoskeletal model to determine JCF at the hip, knee, and ankle. Joint excursions remained consistent across all cadence and powers, but joint moments and JCF differed between 40 and 60 revolutions per minute, with peak JCF force significantly greater at 40 compared to 60 revolutions per minute for all crank powers. Poor correlations were found between mean crank power and peak JCF across all joints. This study provides foundation data and computational methods to enable further evaluation and optimisation of semi-recumbent cycling for application in rehabilitation after SCI and other neurological disorders.

3D Knee Loading during Stationary Cycling: A Comprehensive Model Development and Reliability Analysis

The main purpose of this study was to develop and validate a 3D model for calculating knee joint loads during seated cycling. A 3D inverse dynamics approach was used to calculate knee and ankle joint loads using kinematics and kinetics data. For such a model, four kinematics clusters and three pedal markers were used, integrated with a 6-component force/torque pedal dynamometer. Seven subjects performed one five-minute trial on 75% of their maximum power at fixed cadence of 85 rpms. Data from two consecutive samples of the same cycling trial (first and last minute) were used to validate the model with the mean difference between two samples, Cronbach’s alpha, intraclass correlation coefficient (ICC), and p-value. Results showed high ICC (>0.735) and internal consistency (>0.700) with no statistically significant values (p > 0.050) except for crank angle of peak anterior force and peak axial forces at the knee and minimum normal force (p = 0.010) and minimum crank angle (p = 0.010) on the pedal. Further analyses are required to validate the model between days and to test the sensitivity to mechanical constraints.

Spirulina supplementation improves oxygen uptake in arm cycling exercise

PurposeSpirulina has previously been reported to improve high-intensity exercise performance and hemoglobin. However, spirulina’s effect on arm cycling exercise has yet to be investigated. The purpose of this study was to investigate the responses of spirulina supplementation on hemoglobin and on oxygen uptake, RER and HR during seated arm cycling exercise.MethodsIn a double-blinded randomized crossover design, eleven males untrained in arm cycling ingested 6 g/day of spirulina or placebo for seven days. Seated on the Arm Crank Ergometer, each participant performed a baseline V̇O2max test, and then after supplementation, 2 × 30-min submaximal exercise bouts corresponding to 55% of their V̇O2max, followed by an incremental test to fatigue. A seven-day wash-out period was required between conditions. Oxygen uptake, RER and HR were measured continuously during exercise and hemoglobin measured prior to exercise after both conditions.ResultsSpirulina significantly (p < 0.05) increased Hb in comparison to Placebo (144.1 g/l ± 10.5 Vs 154.5 g/l ± 6.9). After spirulina supplementation, during the 30-min exercise bouts, oxygen uptake and HR were significantly lower (2170 ml/min ± 173 Vs 2311 ml/min ± 189 and 154 bpm ± 14 Vs 149 bpm ± 17), RER was not significantly different. In comparison to placebo, Spirulina significantly increased oxygen uptake at time of fatigue (34.10 ml/min/kg ± 6.03 Vs 37.37 ml/min/kg ± 5.98). Time taken to fatigue was not different.ConclusionSpirulina supplementation significantly reduces oxygen uptake and HR during arm cycling submaximal exercise, allowing for an increased oxygen uptake during an incremental test to fatigue.

Muscle force adaptation to changes in upper body position during seated sprint cycling

ABSTRACTSprint cycling performance depends upon the balance between muscle and drag forces. This study assessed the influence of upper body position on muscle forces and aerodynamics during seated sprint cycling. Thirteen competitive cyclists attended two sessions. The first session was used to determine handlebar positions to achieve pre-determined hip flexion angles (70–110° in 10° increments) using dynamic bicycle fitting. In the second session, full body kinematics and pedal forces were recorded throughout 2x6-s seated sprints at the pre-determined handlebar positions, and frontal plane images were used to determine the projected frontal area. Leg work, joint work, muscle forces and frontal area were compared at three upper body positions, being optimum (maximum leg work), optimal+10° and optimal-10° of hip flexion. Larger hip (p = 0.01–0.02) and reduced knee (p = 0.02–0.03) contribution to leg work were observed at the optimal+10° position without changes at the ankle joint (p = 0.39). No differences were observed in peak muscle forces across the three body positions (p = 0.06–0.48). Frontal area was reduced at optimum+10° of hip flexion when compared to optimum (p = 0.02) and optimum-10° (p < 0.01). These findings suggest that large changes in upper body position can influence aerodynamics and alter contributions from the knee and hip joints, without influencing peak muscle forces.

The Effect of Cycling Intensity on Cycling Economy During Seated and Standing Cycling.

Previous research has shown that cycling in a standing position reduces cycling economy compared with seated cycling. It is unknown whether the cycling intensity moderates the reduction in cycling economy while standing. The aim was to determine whether the negative effect of standing on cycling economy would be decreased at a higher intensity. Ten cyclists cycled in 8 different conditions. Each condition was either at an intensity of 50% or 70% of maximal aerobic power at a gradient of 4% or 8% and in the seated or standing cycling position. Cycling economy and muscle activation level of 8 leg muscles were recorded. There was an interaction between cycling intensity and position for cycling economy (P = .03), the overall activation of the leg muscles (P = .02), and the activation of the lower leg muscles (P = .05). The interaction showed decreased cycling economy when standing compared with seated cycling, but the difference was reduced at higher intensity. The overall activation of the leg muscles and the lower leg muscles, respectively, increased and decreased, but the differences between standing and seated cycling were reduced at higher intensity. Cycling economy was lower during standing cycling than seated cycling, but the difference in economy diminishes when cycling intensity increases. Activation of the lower leg muscles did not explain the lower cycling economy while standing. The increased overall activation, therefore, suggests that increased activation of the upper leg muscles explains part of the lower cycling economy while standing.

Isokinetic Cycling and Elliptical Stepping: A Kinematic and Muscle Activation Analysis

Background: Semi-recumbent cycling exercise has been used as a strategy to complement gait retraining in individuals with disordered walking ability. However, seated elliptical stepping might be a more potent exercise modality for this purpose. Yet, there has not been a kinematic analysis of elliptical stepping exercise, whereby the movement path is produced by a slider-crank mechanism. This study compared the kinematic and leg muscle activation patterns of two isokinetic exercise modalities–cycling and elliptical stepping. Methods: Electromyographic and kinematic signals were collected from twelve healthy able-bodied subjects who performed steady-state seated cycling and stepping exercise. Leg joint excursions of both exercise modes were analysed using 3-D motion analysis. Electromyographic analyses of 10 leg muscles were performed to analyse activation duration and volume (EMG amplitude by time). Results: Kinematic analyses indicated that the elliptical stepping movement created significantly greater hip and knee extension compared to cycling. The ankle joint angles were significantly closer to neutral, with larger ranges of motion during elliptical stepping. EMG descriptors revealed that elliptical stepping elicited greater muscle activation than cycling (9% more volume, 54% longer duration), particularly for the vastii (94% more volume, 150% longer duration) and ankle dorsiflexor muscles (141% longer time) without affecting other muscles’ activation periods. Conclusion: These findings support the efficacy of seated elliptical stepping exercise over cycling for lower-limb training. More potent gait rehabilitation for the neurologically-compromised population might be achieved via seated isokinetic elliptical stepping, since leg movements closer to walking can be executed in a safe environment.

Contoured in-shoe foot orthoses increase mid-foot plantar contact area when compared with a flat insert during cycling

ObjectivesTo determine the effect of contouring of an in-shoe foot orthosis on plantar contact area and surface pressure, as well as perceived comfort and support at the foot-orthosis interface during stationary cycling. DesignA randomised, repeated measures control study. MethodsTwelve cyclists performed steady-state seated cycling at a cadence of 90rpm using a contoured orthosis and a flat insert of similar hardness. Contact area (CA) and plantar mean pressure (PP) were measured using the PEDAR® system, determined for seven discrete plantar regions and represented as the percentage of the total CA and PP respectively (CA% and PP%). Perceived comfort and support were rated using a visual analogue scale (VAS). ResultsThe contoured orthosis produced a significantly greater CA% at the medial midfoot (p=0.001) and lateral midfoot (p=0.009) with a standardised mean difference (SMD) of 1.3 and 0.9 respectively. The contoured orthosis also produced a significantly greater PP% at the hallux (p=0.003) compared to the flat insert with a SMD of 1.1. There was a small non-significant effect (SMD<0.4) for the perceived comfort measures between conditions, but perceived support was significantly greater at the arch (p=0.000) and heel (p=0.013) with the contoured orthoses (SMD of 1.5 and 0.9, respectively). ConclusionsContoured orthoses influenced the plantar surface of the foot by increasing contact area as well as a perception of greater support at the midfoot while increasing relative pressure through the hallux when compared to a flat insert during stationary cycling. No difference in perceived comfort was noted.

Is there evidence for nonthermal modulation of whole body heat loss during intermittent exercise?

This study compared the effect of active, passive, and inactive recoveries on whole body evaporative and dry heat loss responses during intermittent exercise at an air temperature of 30 degrees C and a relative humidity of 20%. Nine males performed three 15-min bouts of upright seated cycling at a fixed external workload of 150 W. The exercise bouts were separated by three 15-min recoveries during which participants 1) performed loadless pedaling (active recovery), 2) had their lower limbs passively compressed with inflatable sleeves (passive recovery), or 3) remained upright seated on the cycle ergometer (inactive recovery). Combined direct and indirect calorimetry was employed to measure rates of whole body evaporative heat loss (EHL) and metabolic heat production (M-W). Mean body temperature (T(b)) was calculated from esophageal and mean skin temperatures, and mean arterial pressure (MAP) was measured continuously. Active and passive recoveries both reversed the reduction in MAP associated with inactive recovery (P <or= 0.05). This response was paralleled by greater levels of EHL during active (207 +/- 53 W) and passive recoveries (203 +/- 55 W) compared with the inactive condition (168 +/- 53 W, P <or= 0.05). However, the greater rate of EHL during active recovery was paralleled by a greater M-W (194 +/- 16 W) compared with inactive recovery (149 +/- 27 W, P <or= 0.001). In contrast, M-W during passive recovery (139 +/- 20 W) was not significantly different from the inactive condition (P = 0.468). Furthermore, there were no differences in T(b) between inactive and passive conditions during the recovery periods (P = 0.820). As such, passive recovery resulted in greater levels of EHL for a given change in T(b) compared with inactive recovery (P <or= 0.05). These results strongly suggest that the progressive increase in core temperature during successive exercise/rest cycles is primarily the result of a baroreflex-mediated attenuation of postexercise whole body evaporative heat loss.

Seated versus standing position for maximization of performance during intense uphill cycling

It is not known whether the seated or standing position favours performance during intensive bouts of uphill cycling. The following hypotheses were therefore tested: (1) the standing position results in better performance at a high power output, while (2) the seated position is best at a moderate power output. We also assessed the seated–standing transition intensity, above which seated cycling should be superseded by standing cycling for maximization of performance. Ten male cyclists (mean age 27 years, s = 3; height 1.82 m, s = 0.07; body mass 75.2 kg, s = 7.0; [Vdot]O2max 70.0 ml · kg−1 · min−1, s = 5.2) performed seated and standing treadmill cycling to exhaustion at 10% grade and at four power outputs ranging from 86% to 165% of their power output at maximal oxygen uptake (Wmax). Power output at maximal oxygen uptake was obtained during determination of [Vdot]O2max. There was no difference in time to exhaustion between the two cycling positions at 86% of Wmax (P = 0.29). All participants performed best at the highest power output (165% of Wmax) when standing (P = 0.002). An overall seated–standing transition intensity of 94% of Wmax was identified. Thus, in general, cyclists may choose either the standing or seated position for maximization of performance at a submaximal intensity of 86% of Wmax, while the standing position should be used at intensities above 94% of Wmax and approaching 165% of Wmax.

Gender Differences in Bicycle Saddle Pressure Distribution during Seated Cycling

The purpose of this study was to investigate the influence of gender, power, hand position, and ischial tuberosity (IT) width on saddle pressure during seated stationary cycling. Twenty-two experienced cyclists (11 males and 11 females) were fitted to an adjustable stationary bicycle and pedaled at 100 and 200 W in both the tops and drops hand positions. An instrumented pressure mat was used to record saddle pressure distribution. Normalized force, maximum sensor pressure, and center of pressure were computed for anterior and posterior regions of the saddle. When increasing power from 100 to 200 W, there were significant reductions in normalized force in all saddle regions and maximum pressure in the posterior region. When moving from the tops to drops hand position, centers of pressure in all regions moved forward, normalized force and maximum pressure on the posterior region decreased, and females (but not males) exhibited an increase in normalized force and maximum pressure in the anterior region. Male centers of pressure were farther forward in the anterior and total saddle regions than they were for females. Females exhibited a larger IT width than males. Interindividual differences in IT width were significantly correlated with the posterior center of pressure fore-aft location on the saddle in the tops and drops hand positions and with the width between the posterior left and right centers of pressure in the tops hand position. There are significant gender-related differences in saddle loading which are important to consider when designing saddles. These differences are especially important when riders are in the handlebar drops and more weight is supported on the anterior pelvic structures.

Biomechanical principles of diarthroses and synarthroses. III: Mechanical aspects of the tibiofemoral joint and role of the cruciate ligaments

The tibiofemoral joint (TFJ) is force-locked. It takes its function as it is compressively loaded. The geometrical shape of the articulating surfaces and the acting force system (given by muscles and gravity) determine the kinematics as well as the quality and extent of static stability of the knee. The mechanism of the TFJ is derived from the anatomical shape of the articulating surfaces. In antero-posterior direction the joint guidance is structurally given by a stretched and overlapped dimeric link chain in lateral and medial region, respectively. Altogether, the two chains are linked up to a four-bar-chain (link quadrangle) that solely allows the tibia to strike backwards. The extent of individual extension can be rejected to morphological data of the femoral condylus. In squat position the extent of mechanical stability of the joint can be changed and even reversed to instability by a rotation of the resulting compressive joint force around the momentary rotational axis of the gear system while the joint position remains unaltered. Thus e.g. the process of straightening up is structurally explained. The cruciate ligaments do not bear any direct mechanical guiding function. They represent a sensor system which structurally resembles a mechanical bridge circuit. Beside detecting the degree of flexion it is able to monitor the indispensable contacting of the articulating surfaces. The menisci represent an additional, similarly working sensor system. At first approximation these two sensor systems are aligned in two planes which are perpendicular. Therefore they form a spatial sensor system. The presented theory is derived from mechanical, morphological, and physiological findings and gets evidence by measurements on knee loads during seated cycling.

Influence of Gender, Power, and Hand Position on Pelvic Motion during Seated Cycling

An understanding of normal pelvic motion during seated cycling is relevant to saddle design and bicycle fitting. In this study, we investigated the effects of gender, power, and hand position on pelvic motion throughout a pedal stroke. We also investigated whether anthropometric factors could explain any interindividual differences observed. Twelve experienced male and 14 experienced female cyclists participated. Each subject was custom fitted to a stationary bicycle and then rode the bicycle at three power outputs (100, 150, and 200 W), with their hands in the tops and drops position. The kinematics of a triad of motion-capture markers, located on posterior pelvic landmarks, were used to characterize pelvic motion. The largest angular excursions were observed in the nonsagittal planes, with the pelvis rotating internally (approximately 3 degrees ) and rolling laterally ( approximately 2 degrees ) toward the downstroke. These pelvic rotations caused the hip on the downstroke side to translate anteriorly and inferiorly. Compared with males, females exhibited greater average anterior pelvic tilt in the drops hand position (males: 21 +/- 3 degrees ; females: 24 +/- 4 degrees ; P = 0.036). Interindividual differences in pelvic motion could not be independently explained by measures of ischial tuberosity width or hamstring flexibility. However, average anterior pelvic tilt was negatively correlated with lumbar flexibility among the males (r = 0.75; P = 0.024), suggesting that this may be an important factor to consider in bicycle fitting. We observed substantial pelvic motion during seated cycling, with experienced female road cyclists exhibiting greater average anterior tilt than their male counterparts. Pelvic motion seems to arise naturally during seated cycling and should be considered when designing saddles and establishing bicycle-fitting procedures.

The Biomechanics Of Standing And Seating Maximal Cycling Power

Previously it has been shown that maximal standing cycling power exceeds seated power in Wingate testing [∼30 seconds] and inertial load testing [∼4 seconds], however the biomechanical basis of this additional power generation remains uninvestigated. PURPOSE The purpose of this investigation was to examine the biomechanics of producing maximal cycling power in both the standing and seated position. METHODS Five trained cyclists [Mean(SD); Age = 27(8) yrs, Height = 173(5)cm, Mass = 70(8)kg] performed maximal 5-second cycling trials on an isokinetic cycling ergometer at 120rpm. Pedal forces, and pedal and crank position were sampled at 240Hz. Hip position was recorded with a 2-camera motion capture system. Two-dimensional leg kinematics were computed using the geometric relationships of the 5-bar linkage. Net joint moments were determined using inverse dynamic techniques. Joint powers for the ankle, knee, and hip were calculated as the product of net joint moment and joint angular velocity. RESULTS Maximal power produced at the crank was significantly greater for the standing versus the seated position [583(51) vs. 516(41) watts]. However, powers produced at the ankle, knee and hip did not differ. Power delivered to the crank by the upper body segment [Hip joint reaction force power] was significantly greater in the standing versus seated position [100(15) vs. 49(8) watts].FigureCONCLUSIONS These data suggest that maximal standing cycling power exceeds maximal seated cycling power due to the ability of the upper body segment to deliver power to the crank, whereas joint powers produced at the ankle, knee and hip did not differ.

Joint Power Distribution Differs During Maximal And Submaximal Cycling

The biomechanics of submaximal cycling have been described by previous investigators; as yet comparable human maximal data has not. The relative contribution of power produced at the ankle, knee, and hip, and transferred across the hip during submaximal cycling likely represents an optimal control strategy. In contrast, the relative contribution of the power produced during maximal cycling likely represents the maximal performance of the muscles that ultimately deliver power to the cranks. PURPOSE The purpose of this investigation was to compare the proportion of crank power produced at the ankle, knee, and hip during maximal and submaximal seated cycling. METHODS Seven trained cyclists [Mean (SD); Age=29(9) yrs, Height=175(7) cm, Mass=73(8) kg] performed maximal [501w±6.9 (right pedal)] and submaximal [71w±10 (right pedal)] cycling trials on an isokinetic cycling ergometer at 90rpm. Pedal forces, and pedal and crank position were sampled at 240 Hz for 5 seconds. Hip position was determined with a 2-camera motion capture system and twodimensional leg kinematics were computed using the geometric relationships of a 5-bar linkage. Net joint moments were determined using inverse dynamic techniques. Joint powers for the ankle, knee, and hip were calculated as the product of net joint moment and joint angular velocity and power delivered across the hip joint was calculated as the dot product of joint reaction force and joint linear velocity and the proportions of total crank power produced at each joint were determined. Relative joint powers were analyzed with repeated measures ANOVA followed by LSD post hoc contrasts. RESULTS Crank power produced at the knee, hip, ankle, and across the hip joint for maximal cycling were 51(4), 26(8), 12(4), and 10(4); (% (SD) respectively) and for submaximal cycling 54(14), 30(13), 6(3), and 5(2); (% (SD) respectively). Repeated measures ANOVA demonstrated a significant interaction of the relative power produced at the ankle and transferred across the hip joint while the relative joint power produced at the knee and hip did not differ. CONCLUSIONS These data suggest that a different control strategy may be utilized from maximal to submaximal cycling. During maximal cycling relatively greater power was produced at the ankle and across the hip joint. These data may have important implications for training of cyclists, and for physical therapy or rehabilitation.

Accuracy assessment of methods for determining hip movement in seated cycling

The goal of this research was to examine the accuracy of three methods used to indicate the hip joint center (HJC) in seated steady-state cycling. Two of the methods have been used in previous studies of cycling biomechanics and included tracking a marker placed over the superior aspect of the greater trochanter, a location that estimates the center of rotation of the hip joint, and assuming that the hip is fixed. The third method was new and utilized an anthropometric relationship to determine the hip joint location from a marker placed over the anterior-superior iliac spine. To perform a comparative analysis of errors inherent in the three methods, a standard method which located the true hip joint center was developed. The standard method involved establishing a pelvis-fixed coordinate system using a triad of video markers attached to an intracortical pin. Three-dimensional motion analysis quantified the true hip joint center position coordinates. To provide data for the comparative analysis, the intracortical pin was anchored to a single subject who pedaled at nine cadence-workrate combinations while data for all four methods were simultaneously recorded. At all cadence-workrate combinations the new method was more accurate than the trochanter method with movement errors lower by a factor of 2 in the vertical direction and a factor of 3 in the horizontal direction. Relative to the errors introduced by the fixed hip assumption, the new method was also generally more accurate by at least a factor of 2 in the horizontal direction and had comparable accuracy in the vertical direction. For computed kinetic quantities, the new method most accurately indicated hip joint force power but the fixed hip method most accurately indicated the work produced by the hip joint force over the crank cycle.

Application of a human multibody model in seated cycling

Application of a human multibody model in seated cycling

Rider/Bicycle Interaction Loads during Standing Treadmill Cycling

This paper provides measurements of rider-induced loads during standing cycling. Two strain gauge dynamometers were used to measure these loads while three subjects rode bicycles on a large motorized treadmill; the cycling situation simulated hill climbing while standing. Comparing the results to those previously published for seated cycling revealed that the loading for standing cycling differed fundamentally from that for seated cycling in certain key respects. One respect was that the maximum magnitude normal pedal force reached substantially higher values, exceeding the weight of the subject, and the phase occurred later in the crank cycle. Another respect was that the direction of the handlebar forces alternated indicating that the arms pulled up and back during the power stroke of the corresponding leg and pushed down and forward during the upstroke. Inasmuch as these forces were coordinated (i.e., in phase) with the leaning of the bicycle, the arms developed positive power.

The effect of lower-limb anatomy on knee loads during seated cycling

Overuse knee joint injuries are the primary injuries to cyclists. Overuse injuries have been intuitively linked to the anatomic structure of the foot because external loads are applied to the foot in cycling. Thus, the structure and function of the foot should dictate in part how the loads are transmitted to the knee joint. Therefore, it was hypothesized that patterns in knee loads are related to the anatomic structure of the foot. To test this hypothesis, peak knee loads (dependent variables) were related to anatomical variables (independent variables) through statistical analyses. This required first the detailed evaluation (i.e. measurement) of the anatomical structure of the foot and leg for 23 subjects. Next, three-dimensional knee joint loads were determined for a standardized riding condition. The results of the statistical analyses indicated that a group of cyclists with the most extreme inversion of the forefoot relative to the transverse plane developed significantly greater average posterior knee force and extensive knee moment. In addition, a number of anatomical variables significantly accounted for the variability in peak values of the posterior force, the extensive moment, the varus/valgus moment and the external axial moment. Based on these results, the hypothesis is accepted.

Three-dimensional knee joint loading during seated cycling

The hypothesis which motivated the work reported in this article was that neglecting pure moments developed between the foot and pedal during cycling leads to a substantial error in computing axial and varus/valgus moments at the knee. To test this hypothesis, a mathematical procedure was developed for computing the three-dimensional knee loads using three-dimensional pedal forces and moments. In addition to data from a six-load-component pedal dynamometer, the model used pedal position and orientation and knee position in the frontal plane to determine the knee joint loads. Experimental data were collected from the right leg of 11 male subjects during steady-state cycling at 90 rpm and 225 W. The mean peak varus knee moment calculated was 15.3 N m and the mean peak valgus knee moment was 11.2 N m. Neglecting the pedal moment about the anterior/posterior axis resulted in an average absolute error of 2.6 N m and a maximum absolute error of 4.0 N m in the varus/valgus knee moment. The mean peak internal and external axial knee moments were 2.8 N m and 2.3 N m, respectively. The average and maximum absolute errors in the axial knee moment for not including the moment about an axis normal to the pedal were found to be 2.6 N m and 5.0 N m, respectively. The results strongly support the use of three-dimensional pedal loads in the computation of knee joint moments out of the sagittal plane.

An angular velocity profile in cycling derived from mechanical energy analysis

The contributions of this article are twofold. One is a procedure for determining the angular velocity profile in seated cycling that maintains the total mechanical energy of both legs constant. A five-bar linkage model (thigh, shank, foot, crank and frame) of seated (fixed hip) cycling served for the derivation of the equations to compute potential and kinetic energies of the leg segments over a complete crank cycle. With experimentally collected pedal angle data as input, these equations were used to compute the total combined mechanical energy (sum of potential and kinetic energies of the segments of both legs) for constant angular velocity pedalling at 90 rpm. Total energy varied indicating the presence of internal work. Motivated by a desire to test the hypothesis that reducing internal work in cycling will reduce energy expenditure, a procedure was developed for determining the angular velocity profile that eliminated any change in total energy. Using data recorded from five subjects, this procedure was used to determine a reference profile for an average equivalent cadence of 90 rpm. The pahse of this profile is such that highest and lowest angular velocities occur when the cranks are near vertical and horizontal respectively. The second contribution is the testing of the hypothesis that the reference angular velocity profile serves to effectively reduce internal work for the subjects whose data were used to develop this profile over the range of pedalling rates (80–100 rpm) naturally preferred. In this range, the internal work was decreased a minimum of 48% relative to the internal work associated with constant angular velocity pedalling. The acceptance of this hypothesis has relevance to the protocol for future experiments which explore the effect of reduced internal work on energy expenditure in cycling.