Biomechanical Analysis of Lower Limb Segments During Variable Speed Cycling.

Ajayi, A.B (2014)

A Thesis Submitted to the School of Postgraduate Studies, University of Lagos.

Thesis

This work undertakes the biomechanical analysis of the lower limb segments during variable speed cycling using inverse dynamics approach. Cycling interventions have been suggested for cardio-respiratory fitness as well as for patients with spinal cord injuries, stroke, mobility impairments and osteoarthritis. In the course of variable speed cycling, fatigue does set in at the lower limb after a period of usage or when there are abuses. Attempts by cycling athletes to outdo one another can impact negatively on their lower limbs during sports. Similar things do occur in recreation and rehabilitation. Therefore, it is important to understand the dynamics of the biomechanics of the lower limb segments (comprising the ankle, the knee joint and the hip) during variable speed cycling so as to mitigate the effects. The lower limb segments are model as a dynamic five bar linkages with kinematics, kinetics, and joints moments equations developed using inverse dynamics. Parametric studies are carried out using known values in order to evaluate the effects of saddle height; horizontal acceleration and crank speed on the lower limb segments are evaluated. Results show that at crank speeds above 64 rpm, the knee joint moment was the highest, followed by hip and then the ankle. A horizontal acceleration of 2 m/s2 was discovered to be appropriate and is therefore recommended. It was also discovered that as the saddle height was reduced below 50% of the total length of the lower limb segments, the joints moments become very high; this can eventually lead to fatigue. A saddle height of 75% of the total length of the lower limb segments minimizes all the three joint moments. It is therefore concluded that in other to minimize knee joint related fatigue which can lead to injuries during recreation and fitness, the saddle height should be 75% of the total length of the lower limb segments and crank speed not exceeding 64 rpm. For competition, the saddle height should be 90 – 100 % of the total length of the lower limb segments and horizontal acceleration of 2 m/s2 to be maintained.

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