SWIMMING VELOCITIES ABOVE STEADY STATE INVOKE CHANGES IN STROKE FACTORS
Pelarigo, J. G., Denadai, B. S., Fernandes, B. D., Santiago, D. R., César, T. E., Barbosa, L. F., & Greco, C. C. (2010). Stroke phases and coordination index around maximal lactate steady-state in swimming. A paper presented at the XIth International Symposium for Biomechanics and Medicine in Swimming, Oslo, June 16–19, 2010.
This study analyzed changes in stroke parameters (stroke length and rate) and arm coordination (propulsive and non-propulsive phases and Index of Coordination) when swimming at and above (102.5%) maximal lactate steady-state. Endurance swimmers (N = 12) performed on different days: 1) 200 and 400-m all-out tests to determine critical speed, and; 2) two to four 30-minute sub-maximal continuous tests at imposed swim paces, to determine the maximal lactate steady-state. Video analysis was used to determine the stroke length and rate, stroke phases, and the Index of Coordination. The Index of Coordination was determined using the lag times between the propulsive phases of each arm (Chollet et al., 2000). Blood lactate and stroke technique variables were analyzed at the 10th and 30th minute of each imposed speed test.
There were significant differences among maximal lactate steady-state (~1.22 m/s), 102.5% of maximal lactate steady-state (~1.25 m/s), and critical speed (~1.30 m/s) tests. Stroke rate and length were maintained during the maximal lactate steady-state test swum but were modified in the 102.5% maximal lactate steady-state test (stroke rate increased and stroke length decreased). All stroke phases were maintained during the maximal lactate steady-state test. However, the propulsive phase B (pull) increased in the 102.5% maximal lactate steady-state test. There was no significant effect of exercise intensity and time on the Index of Coordination.
Implication. Changes in stroke parameters (reduction in stroke length and increase in stroke rate) and arm coordination (increase in the propulsive pull phase) of well-trained swimmers during long distance imposed speed tests performed at moderately high intensity domain (i.e., below critical speed), occurs only above the maximal lactate steady-state (beyond metabolic equilibrium).
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