An assessment of the kinematic and metabolic characteristics of the breaststroke
This thesis aimed to provide an examination of the kinematic and metabolic responses of breaststroke swimming, including the effects of changing pace. Study 1 provided a description of competition swimming including rarely reported temporal elements (start time CST) to 15 m, turning times (IT s) for the 7.5 m ingress and 7.5 m egress, end time (ET) - fmal5 m) as well as repeated measurements of turning times, mid-pool swimming velocity, stroke rate (SR) and stroke length (SL) as races progressed. Mid-pool swimming velocity, ST and IT were found to be significantly related with finishing time (FT) and each other suggesting that coaches should adopt an holistic approach to the training of breaststroke swimmers. Stroke rate and IT were found to increase as races evolved while mid-pool SV and SL decreased. A detailed comparison of the 100 m and 200 m events suggested that event specific preparation might be needed and that there was a potential for swimmers of the 200 m event to reduce their ST. In Study 2 a multiple regression analysis utilising kinematic and temporal variables demonstrated that SV was the primary determinant of FT. Turning time was the secondary determinant of IT in all events except the men's 100 m where ST had greater relative importance. The analysis produced precise predictive equations of FT which could be used by coaches to predict race performance and to prescribe race pace training. Studies 3, 4 and 5 established that breaststroke swimmers could be paced precisely and reliably using the Aquapacer during moderate to high intensity 200 m breaststroke trials, subject to the onset of fatigue. Stroke kinematic (SR, stroke count SC) and metabolic responses (blood lactate, gas exchange and heart rate) elicited during the trials of Study 3 were found to be reproducible. During 200 m trials paced at 98 %, 100 % and 102 % of a subject's mean maximal 200 m speed (Study 4) SR was elevated to increase swimming velocity, and to compensate for a deterioration in SL caused by lactacidosis. Lactacidosis occurred because swimmers were operating beyond their maximal aerobic power even during the 98 % trial and hence the additional speed in the faster trials required an increased anaerobic contribution. In support of this, post exercise blood lactate concentrations were significantly negatively related to FT in the 98 % and 100 % trials. Turning times were initially shorter at the start of the faster trials but a marked deterioration followed demonstrating their sensitivity to lactacidosis. An anomaly across studies was that changes in kinematic variables were less predictable during the final 100 In of positively split men's 200 In races (Study 1) WId trials (Study 4). A subsequent comparison of positively split, evenly split and negatively split 175 In trials (Study 5) demonstrated that stroke kinematics remained significantly related over the whole distance of the evenly split trial compared with the positively split trial. Subjects also demonstrated reduced blood lactate, RER and RPE values following the evenly split trial compared with the positively split trial. It was suggested that coaches should experiment with an evenly split race strategy to determine if it produces shorter FT s compared with the positively split patterns currently adopted in competition. A common finding was that breaststroke swimmers exhibited unique SR : SL ratios so that both SR and SL were poorly related to FT in all the studies. It was suggested that coaches, using the Aquapacer" , could entrain a swimmer's ideal SR to elicit a more evenly paced and consistent competition performance. Pacing the ideal SR could also be used for a race specific test, because if a swimmer becomes better able to maintain IT s and SL over a given distance the FT would be improved which might indicate a potential for an improved competition performance. Finally, a model of a maximal even paced 200 m breaststroke swim was outlined and the effect of a change of pace discussed with respect to the model.