The effect of saddle position on maximal power output and moment generating capacity of lower limb muscles during isokinetic cycling.
ABSTRACT Saddle position affects mechanical variables during submaximal cycling, but little is known about its effect on mechanical performance during maximal cycling. Therefore, this study relates saddle position to experimentally obtained maximal power output and theoretically calculated moment generating capacity of hip, knee and ankle muscles during isokinetic cycling. Ten subjects performed maximal cycling efforts (5 s at 100 rpm) at different saddle positions varying ± 2 cm around the in literature suggested optimal saddle position (109% of inner leg length), during which crank torque and maximal power output were determined. In a subgroup of 5 subjects, lower limb kinematics were additionally recorded during submaximal cycling at the different saddle positions. A decrease in maximal power output was found for lower saddle positions. Recorded changes in knee kinematics resulted in a decrease in moment generating capacity of biceps femoris, rectus femoris and vastus intermedius at the knee. No differences in muscle moment generating capacity were found at hip and ankle. Based on these results we conclude that lower saddle positions are less optimal to generate maximal power output, as it mainly affects knee joint kinematics, compromising mechanical performance of major muscle groups acting at the knee.
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ABSTRACT: Currently a substantial amount of cycling research and training is conducted in sports science laboratories utilising cycle ergometers and/or turbo trainers. These devices have been widely used within cycling research, however, they have been found to be difficult to set-up and adjust, particularly whilst in use as well as to replicate a force profile similar to that experienced when competing. This study details the development of a novel cycle ergometer that incorporates automatic bike set-up and adjustment. The ergometer was designed in accordance with a design specification developed through the use of needs analysis of elite cyclists and performance scientists. The user analysis identified a need for increased adjustability (seat height (SH), seat set back (SS), handlebar drop (HD) and handlebar reach (HBR)) and positioning accuracy, whilst maximising the stability and stiffness of the frame when conducting maximal effort trials particularly at the bottom bracket. The novel ergometer incorporates two lifting columns to provide HD adjustment from 411mm to 868mm and SH adjustment from 568mm to 928mm. The two lifting columns were mounted on two linear rails to provide horizontal adjustment of the handlebars relative to the seat, and seat relative to the bottom bracket. The motors on both the lifting columns and linear rails were fitted with HTL encoders, increasing the positioning accuracy to+/- 0.1mm. An anti-coast brake was also fitted to prevent the lifting columns or linear rails from slipping whilst in use. When comparing existing set up time, adjusting from the largest to smallest set-up, current ergometers can take up to 30minutes, whereas the new ergometer takes 8seconds. To minimise twisting of the frame during maximal effort cycling, the bottom bracket has been mounted on a 65mm x 65mm square column. Finite element analysis of the structure identified that it would remain stable whilst subjected to up to 800Nm of torque. In conclusion the development of the novel ergometer allows for greater adjustability, speed of set-up and maximise frame stability during use.Procedia Engineering. 01/2011; 13:69-74.