Flatwater sprint kayaking performance can be assessed through the analyses of average boat velocity a paddler can produce, which has been shown to be directly linked to the levels of force production. Furthermore kayaking has been the subject of substantial level of investigation, within which research has identified that the evolution of equipment and resultantly technique has a direct effect on performance. The focus of the previous research has revolved around the upper limbs, with the trunk and lower limbs viewed as an inconsequential base around which the upper limbs move. Therefore the current thesis attempts to identify the application of the entire body during kayak paddling and clarify the importance of trunk and leg contributions to performance. A notational analysis of technique was conducted comparing novice, national and international level paddlers. International paddlers displayed significantly (P < 0.05) lower race and stroke times, as a result of significantly higher stroke rates. In addition aspects of technique were ranked from zero to five from which international paddlers displayed significantly (P < 0.05) greater trunk rotation, leg motion, stroke width, and forward reach. These findings were supplemented by the international paddlers entering the paddle significantly closer to the centre line of the kayak, while holding a fixed forward lean position of the trunk. These findings provide important factors within technique that can be identified visually; however further investigation was required to identify their importance in the development of force and kayak velocity. Consequently the development of an on-water analysis system was required to ensure a comprehensive analysis of technique. This was conducted through the combination of kinetic, 3-demensional kinematic, electromyographic and electrogoniometric analysis methods, using subjects (n = 8) with international experience. Subjects were prepared with passive surface electrodes and joint markers, and completed the testing protocol following completion of informed consent and a medical questionnaire. Statistical analysis identified that a moderate positive significant predictive relationship (R1= 0.529, P<0.05) existed between peak force and mean velocity during the left paddle stroke. Separating the trunk into thoracic and lumbar regions revealed a significant negative predictive relationship (P < 0.05) between velocity and range of lumbar spine rotation. Further significant (P < 0.05) findings were identified between activation levels of the rectus abdominus, external obliques and the production of force and velocity. The combination of these findings indicated that the lower trunk acted as a strong stable base against which force was produced increasing average kayak velocity. The activation of the left rectus femoris displayed significant relationships (P < 0.05) with force and velocity during both left and right strokes; indicating that the legs act as braces against which the force is transferred to the kayak. These findings reinforced those identified during the notational analysis, indicating that the legs and trunk play a fundamental role within the development of kayak velocity and therefore performance. It is therefore important that paddlers ensure that the musculature of the trunk and legs are used during performance and that the vital axial rotations occurring in the spine are produced in the thoracic region.

Soccer consists of many different types of sports specific movement. The present level of understanding of non-linear motion is negligible yet required if improvements are to be made in technique and performance of such actions. This thesis aimed to establish mechanisms for non-linear motion relevant to soccer performance. Preliminary analysis of curvilinear motion involved electromyographical analysis in selected muscles of the lower extremity at different grades of curvature. Results revealed adaptation of temporal muscle activity at the tightest grade of curvature. Adaptation occurred in both legs, but predominantly the outside leg, with increased duration of activity after footstrike (Smith et al., 1997). Stride kinematics were also altered, as increasing curve severity gave reduced stride length and increased stride frequency. Foot contact time was not changed as a function of curvilinear motion (P > 0.05), giving an increased proportion of the stride cycle in the stance phase. Rear foot contact time increased as a function of curve severity (P $ 0.05). To describe and quantify adaptation of lower limb movement in curvilinear motion, three-dimensional kinematics were used. Subjects (n = 8) wore soccer footwear on natural turf. Ranges of motion at the lower extremity were increased at the faster of the two velocities tested (4.4 and 5.4 ms·] ± 5%), yet tended to reduce with curve severity. The inside leg displayed more differences in angular displacement with curve severity, and the ankle joint showed to be a key adaptive site. Ground reaction forces of two consecutive footfalls were performed on natural turf to assess relative contributions of the two limbs during straight and curvilinear motion at a 5m radius. Total force over two footfalls was greater during straight motion. A mechanism of lowered centre of gravity during curvilinear motion was proposed. During curvilinear motion the outside leg was associated with greater force values in all three planes, displaying a greater contribution to curvilinear motion. Force measurements on natural turf were used to assess different sole configuration during three soccer specific moves. A modern moulded sole was found to be associated with greater maximum friction, also lower vertical ground reaction forces during a Cruyff turn and lower overall forces during the shot. This thesis established biomechanical adaptations and suggested mechanisms during non-linear motion in the soccer player. The research represented the first experimental investigations in this area and therefore recommendations for future study are considered.