EFFECT OF DIFFERENT HANDLEBAR HAND POSITIONS ON FAST BRAKE LEVER REACHING MOVEMENTS IN CYCLING
Keywords: cycling, braking, handlebar, hand positions
AbstractINTRODUCTION: The aim of the present study was to evaluate the effect of different kinds of handlebar hand positions on fast brake lever reaching movements. The assumption motivating this study was that riding positions that provide quick access to brake levers allow athletes to more easily manage the braking operation when they are forced to suddenly decrease bicycle speed or change direction to avoid an unexpected obstacle. METHODS: Three high-level road cyclists were the subjects of this study. Each athlete was tested while pedaling on his own racing bicycle mounted on a magnetic braked roller simulator. The bikes were equipped with a Cinelli Spinaci clipon handlebar. While pedaling, the athletes were asked to reach, as quickly as possible, the brake levers and try to brake the wheels’ rotation in the shortest possible time. Seven handlebar starting hand positions were predefined and investigated, including the placement of the hands on the clip-on handlebar. The subjects performed the braking actions in response to external stimuli (visual and acoustic) and were free to choose when to start the movement. For each of the experimental conditions, data for 10 trials were acquired. The ELITE motion analysis system was used at a sampling rate of 100 Hz to collect the 3-D kinematic variables of the right upper limb segments with respect to the handlebar and right brake lever frame. Five retro-reflective markers were glued on the subjects’ skin, and markers were located on sticks fixed to the right brake lever and to the handlebar. To account for bicycle movements, the measured coordinates were referred, by trigonometry, to a reference system whose origin was the handlebar marker. The time the rider took to reach the right brake lever was defined as the time from the first detectable movement of the marker fixed on the third finger of the right hand (distal end of the 2nd phalanx) until the first movement of the brake lever marker. The effect of the different handlebar hand positions on brake lever reaching times was analyzed with one-way ANOVA. The existence of significant differences between conditions was then tested using the Newman Keuls post hoc test. RESULTS: The results of the data analysis were as follows: • In each of the examined experimental conditions, the time the athletes took to reach the brake levers (lower than 300 ms) represented a small fraction of the total time necessary to stop a bicycle after an emergency signal was perceived. • Hand positions slightly affected the access time to the brake levers that, on the average, ranged from 150 ms to 280 ms. Lower values were measured when the hands were placed very close to the brake lever mounts. • Riding with the hands placed on the clip-on handlebar lead to brake lever reaching- times as high as those measured for other traditional positions with the hand placed on the top of the handlebar.
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