Jason Hynd

Background: Contemporary studies have investigated the effects of bicycle saddle height for optimal performance and injury prevention. A recent review established a dynamic knee flexion angle of 25˚-30˚ for optimal economy, anaerobic power, and knee tracking (Bini et al., 2011: Sports Medicine, 41, 463-476). Muyor et al, (2011: Journal of Human Kinetics, 29, 15-23), investigated hamstring extensibility within 96 highly trained cyclists. They concluded that shortened hamstrings had a negative influence over thoracic spinal curvature, yet no influence over saddle height. Whereas, Ferrer-Roca et al (2012: Journal of Strength and Conditioning Research, 26, 3025- 3029) examined 23 high level competitive male road cyclists and concluded that a lack of flexibility may have an influence over lower preselected saddle heights (> 40˚ knee flexion angle). Consequently, there remains uncertainty whether preselected saddle height may be dependent on hamstring extensibility. Purpose: The purpose of the study was to investigate the influence of hamstring extensibility on preselected saddle height within experienced competitive cyclists. It was suggested that preselected saddle height may be dependent on hamstring extensibility to enable a 25˚-30˚ knee flexion angle. Methods: Participants consisted of 32 moderate to high level male and female road cyclists (35.8 ± 8.4 years; 178.22 ± 11.0 cm; 77.7 ± 13.4 kg). They used their own individually set-up road bicycle, which was placed on an indoor wind trainer. Hamstring extensibility was measured using the passive knee extension test. Dynamic 2D analysis was used to measure bicycle knee flexion and passive knee extension angles. A cycling questionnaire was also used to determine experience, training and competition levels. Results: Pearson’s correlation coefficients revealed bicycle knee flexion angle, years cycling (r = -0.35, p < 0.05), training volume, (r = -0.54, p< 0.01) and competition duration (years) (r = -0.62, p< 0.01) were significant. Whereas, no significance was identified with pre (r = 0.12) and post (r = 0.12) passive knee extension (p > 0.05). Discussion: Results suggest that sustained time period on the bike rather than hamstring extensibility determines preselected saddle height. In particular, being competitive for a longer duration precedes either volume or number of years cycling. However, it is apparent that in agreement with Muyor et al., (2011) a single variable such as hamstring length does not predetermine optimal saddle height. In addition, as suggested by Ferrer-Roca et al., (2012), experienced cyclists are unable to achieve a knee flexion angle of 25˚, unless they have sufficient flexibility. Conclusion: Results reveal that with experience, a competitive cyclist’s subjective and objective interpretation of their preselected saddle height becomes more consistent. Although hamstring extensibility does not appear to influence pre-selected saddle height, an initial 35˚ rather than 25˚ knee flexion angle is recommended. Future research should consider mixed methodologies, to further establish safe and effective recommendations for optimising bicycle fit. References Bini, R., Hume, P.A., & Croft, J.L. (2011). Effects of bicycle saddle height on knee injury risk and cycling performance. Sports Medicine, 41, 463-476. Ferrer-Roca, V., Roig, A., Galilea, P., & Garcia Lopez, J. (2012). Influence of saddle height on lower limb kinematics in well trained cyclists: static vs dynamic evaluation in bike fitting. Journal of Strength and Conditioning Research, 26, 3025- 3029. Muyor, J. M., Alacid, F., & Lopez-Minarro, P.A. (2011). Influence of hamstring muscles extensibility on spinal curvatures and pelvic tilt in highly trained cyclists. Journal of Human Kinetics, 29, 15-23.

Tibial plateau fractures present a challenging problem for elite athletes and medical personnel, with many athletes failing to return to previous sporting levels post fracture (Johansson etal, 1992). An elite professional female endurance mountainbiker (Age: 32, Height: 1.58m, Body Mass: 51kg) presented 3 weeks post injury with a severe left tibial plateau fracture, caused by a fall when skiing. An orthopaedic surgeon in France inserted two screw fixations from lateral to medial condyles within the left tibia. X-rays and CT scans revealed a large degree of damage to the superolateral surface of the tibial plateau. The surgeon described an unusual and potentially career threatening injury. The athlete was advised to completely rest for a minimum of 10 weeks. This created uncertainty and concern for future career status and sponsorship. Prior to injury, a 12 week training period in France involved intensive skiing and running on steep alpine roads. During this time the athlete experienced progressive knee pain, perhaps caused by a change in knee load relative to high volume cycling. According to Bargfeldt etal (2011) high impact training loads may cause microcracks within the tibia. Furthermore, female athletes are at particular risk due to amenorrhea, a reduction in oestrogen levels and resultant reduction in bone mass.

OBJECTIVE: Upper leg skeletal or lean tissue mass, strength and muscle quality have emerged as time-sensitive indices of muscular health. The aim of this study was to generate a comparative data set based on these indices, in healthy young (n=30, 29.0 ± 3.0 y old) and older (n=32, 58.7 ± 2.8 y old) adults, in order to evaluate their construct validity in establishing cut-points for muscle health. APPROACH: Whole body and upper leg lean tissue mass was obtained (iDXATM; GE Healthcare, Madison, WI) prior to the assessment of maximal voluntary isometric torque of the knee extensors and flexors (Cybex Isokinetic Dynamometer; Humac Norm, USA). MAIN RESULTS: Peak isometric upper leg torque showed the greatest age-related difference (-29.0%), followed by muscle quality (-19.1%) and upper leg lean tissue mass (9.8%). SIGNIFICANCE: Cut-points based on Z and T-scores generated from the young adult mean suggest muscle quality demonstrates the greatest construct validity toward the aim of classifying the muscular health of adults. Data generated from large, representative and sex-specific samples are required to adequately classify the muscular health of adults.