Metabolic and Kinematic Effects of Self-Selected Q Factor During Bike Fit

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.

Comparative study on the efficiency of motor rehabilitation of the lower limbs using a stationary horizontal bicycle versus a standard therapeutic program

Abstract: The purpose of the present study is to compare the efficiency of two physiother-apeutic programs for rehabilitation of the lower limbs, one using a stationary bicycle and the other one being a standard program, targeting muscle imbalance deficit. Subjects are outpatients - the control group (C n=5), 58.67 ± 11.67 years, received a standard rehabilita-tion program, and the experimental group (E n=5), 56.67 ± 12.14 years, received a pro-posed rehabilitation program implying a stationary bicycle. Equipment used is for muscle imbalances – sensor attached to bicycle pedals, for joint testing – goniometer, for heart rate smart watch, pain assessment – VAS numeric scale, and for perceived effort Borg scale. The rehabilitation program including the stationary horizontal bicycle obtained better re-sults in terms of pain control (T-Test p C/E=.004/.001 and Wilcoxon p C/E=.039/.041) and the correction of muscular imbalances (T-Test p C/E=.003/.000, r= .990/.997) related to the lower limbs, with the mention that both programs recorded statistically significant results regarding functionality. HR values for the control group and experimental group < THR values, aerobic conditioning with the submaximal effort being essential for rehabilitation. Both programs maintained the same perceived level of effort with an average of 3.6 Borg- moderate effort, respectively mild-moderate dyspnea. Keywords: rehabilitation; lower limbs; stationary bicycle; muscle imbalance; pedal sensor; ana-log value; heart rate (HR); target heart rate (THR).

Physiological, biomechanical, and subjective effects of medio-lateral distance between the feet during pedalling for cyclists of different morphologies

Improper medio-lateral distance between the feet in cycling can increase the risk of injuries and decrease performance due to hip/knee/ankle misalignment in the frontal plane. The objective of this study was to measure the impact of pedal spacing changes during pedalling on the biomechanical, physiological, and subjective variables of people with different morphologies. Twenty-two cyclists were divided into two groups according to their pelvis width (narrow and wide). They performed four submaximal pedalling tests with different pedal spindle lengths (+20 mm, +40 mm, and +60 mm compared to the pedal spindle lengths of standard road bikes). EMG activity, 3D joint kinematics of the lower limbs, comfort, and perceived exertion were measured during each test. Moreover, gas exchange data were collected to measure gross mechanical efficiency and cycling economy. No significant differences in muscular activity or joint kinematics were observed among the four experimental conditions. However, gross mechanical efficiency, cycling economy, and perceived comfort significantly improved while perceived exertion significantly reduced with the narrowest pedal spacing for the whole population, as well as for the narrow and wide pelvis groups. Therefore, the lowest medio-lateral distance between the feet seems more suitable for comfort and performance improvement, irrespective of the individual's morphology.

Increased Q-Factor increases frontal-plane knee joint loading in stationary cycling

BACKGROUND

Q-Factor (QF), or the inter-pedal width, in cycling is similar to step-width in gait. Although increased step-width has been shown to reduce peak knee abduction moment (KAbM), no studies have examined the biomechanical effects of increased QF in cycling at different workrates in healthy participants.

METHODS

A total of 16 healthy participants (8 males, 8 females, age: 22.4 ± 2.6 years, body mass index: 22.78 ± 1.43 kg/m², mean ± SD) participated. A motion capture system and customized instrumented pedals were used to collect 3-dimensional kinematic (240 Hz) and pedal reaction force (PRF) (1200 Hz) data in 12 testing conditions: 4 QF conditions-Q1 (15.0 cm), Q2 (19.2 cm), Q3 (23.4 cm), and Q4 (27.6 cm)-under 3 workrate conditions-80 watts (W), 120 W, and 160 W. A 3 × 4 (QF × workrate) repeated measures of analysis of variance were performed to analyze differences among conditions (p < 0.05).

RESULTS

Increased QF increased peak KAbM by 47%, 56%, and 56% from Q1 to Q4 at each respective workrate. Mediolateral PRF increased from Q1 to Q4 at each respective workrate. Frontal-plane knee angle and range of motion decreased with increased QF. No changes were observed for peak vertical PRF, knee extension moment, sagittal plane peak knee joint angles, or range of motion.

CONCLUSION

Increased QF increased peak KAbM, suggesting increased medial compartment loading of the knee. QF modulation may influence frontal-plane joint loading when using stationary cycling for exercise or rehabilitation purposes.

The association of bike fitting with injury, comfort, and pain during cycling: An international retrospective survey

Although bike fitting is recommended to help reduce injury risk, little empirical evidence exists to indicate an association between bike fitting and injury incidence. The aim of the study was to determine the effect of bike fitting on self-reported injury, comfort, and pain while cycling from a worldwide survey of cyclists. A total of 849 cyclists completed an online questionnaire between February and October 2016. Questionnaire collected data on respondent demographics, cycling profile, bike fitting, comfort and pain while cycling, and injury history. The main predictor variable was bike fitting (yes, by the respondent, i.e. user bike fitting; yes, by a professional service; or no). Covariates included demographic and cycling profile characteristics. Logistic regression models estimated the odds of injury within the last 12 months, reporting a comfortable body posture while cycling, and not reporting pain while cycling. Odds ratios (OR) with 95% confidence intervals (CI) were reported. User bike fitting was associated with increased odds of reporting a comfortable posture (OR = 2.28, 95%CI: 1.06, 4.68). User (OR = 2.35; 95%CI: 1.48, 3.84) and professional bike fitting (OR = 2.35; 95%CI: 1.42, 3.98) were both associated with increased odds of not reporting pain while cycling. No associations were found between bike fitting and injury within the last 12 months. In conclusion, we found an association between bike fitting and reported comfort and pain while cycling. We recommend integrating bike fitting into cycling maintenance. However, further studies with longer follow-up are necessary to determine the presence of an association between bike fitting and injury.

Effect of saddle height on skin temperature measured in different days of cycling

Infrared thermography can be useful to explore the effects of exercise on neuromuscular function. During cycling, it could be used to investigate the effects of saddle height on thermoregulation. The aim of this study was to examine whether different cycling postures, elicited by different knee flexion angles, could influence skin temperature. Furthermore, we also determined whether the reproducibility of thermal measurements in response to cycling differed in the body regions affected or not affected by saddle height. Sixteen cyclists participated in three tests of 45 min of cycling at their individual 50 % peak power output. Each test was performed in a different knee flexion position on the bicycle (20°, 30°, 40° knee flexion when the pedal crank was at 180°). Different knee angles were obtained by changing saddle height. Skin temperatures were determined by infrared thermography before, immediately after and 10 min after the cycling test, in 16 different regions of interest (ROI) in the trunk and lower limbs. Changes in saddle height did not result in changes in skin temperature in the ROI. However, lower knee flexion elicited higher temperature in popliteus after cycling than higher flexion (p = 0.008 and ES = 0.8), and higher knee flexion elicited lower temperature variation in the tibialis anterior than intermediate knee flexion (p = 0.004 and ES = 0.8). Absolute temperatures obtained good and very good intraday reproducibility in the different measurements (ICCs between 0.44 and 0.85), but temperature variations showed lower reproducibility (ICCs between 0.11 and 0.74). Different postures assumed by the cyclist due to different saddle height did not influence temperature measurements. Skin temperature can be measured on different days with good repeatability, but temperature variations can be more sensitive to the effects of an intervention.