The physiological and biomechanical changes during a 100m breaststroke swim

Abstract

This thesis investigated changes in kinematics, including arm-leg co-ordination, (n =26), intra-cyclic velocity fluctuations and arm-leg co-ordination (n =18), duration and coordination of muscle activity in the upper and lower extremity muscles using surface electromyography (sEMG) (n= 8), and evaluated fatigue in selected upper body, trunk and lower limb muscles by means of frequency parameters of sEMG (n =8) during a maximal 100 m breaststroke swim performed from a water start. 
Arm-leg co-ordination was defined using two transition phases that described the continuity between the recovery and propulsive phases of the arms and the legs: CPhase 1, corresponding to the time between the end of the leg propulsion and the start of the arm propulsion phases; and CPhase 2, corresponding to the time between the end of the arm propulsion phase and the start of leg propulsion phase. Intra-cyclic velocity fluctuations were calculated from peak velocities of the greater femoral trochanter during the arm and leg propulsive phases and the minimum velocities attained during the recovery of the arms and the legs. Video analysis (50 Hz) was used to analyse swim speed (not influenced starting, turning or finishing techniques), stroke length, stroke rate and stroke efficiency. Surface electromyography (sEMG) was collected from the pectoralis major, latissimus dorsi, posterior deltoids, biceps brachii, triceps brachii, biceps femoris, rectus femoris, vastus lateralis, vastus medialis, gluteus maximus, erectus spinae and rectus abdominals. 
Over the duration of a 100 m breaststroke swim there was a significant decrease in the clean swim speed (p < 0.05) with subsequent decreases in stroke length and stroke efficiency with no significant change in stroke rate (p > 0.05). As a consequence of a decrease in clean swim speed there were alterations in the arm-leg co-ordination with a significant decrease (p < 0.05) in CPhase1 of the stroke cycle. There were also significant decreases (p < 0.05) in the active phase (AF) of the major upper and lower muscles used in breaststroke swimming. There was a no significant change (p > 0.05) in the mean power frequency (MNF) of any of the muscles that were studied. 
It was concluded that participants in the study were affected by fatigue and used compensatory mechanism and strategies in an attempt to maintain clean swim speed, which resulted in alterations in the alterations in the combination of SR and SL, altered intra muscular co-ordination and alterations in the arm-leg co-ordination within the stroke cycle.

Date of Award	2012
Original language	English
Awarding Institution	Coventry University
Supervisor	Rob James (Supervisor) & Carl Payton (Supervisor)