The behaviour of kinematic parameters during a time to exhaustion test at VO2max in elite swimmers

The aim of this study was to analyse, in swimming pool conditions, the behaviour of kinematic parameters - stroke rate (SR), stroke length (SL) and stroke index (SI) - during a time to exhaustion test performed at the minimum velocity that elicits maximal oxygen uptake (TLimvVO(2)max) in elite freestyle swimmers. Eleven swimmers from the National Portuguese Swimming Team (five male and six female) performed an intermittent incremental test for vVO(2)max assessment and an all-out swim at vVO(2)max to determine TLim-vVO(2)max and to analyse the evolution of the kinematic parameters throughout the test. SR increased and SL (and SI) decreased during the TLim-vVO(2)max test, as a general tendency. When the differences in SR, SL and SI between each 12.5% section of the test were tested, a significant increase in SR and a decrease in SL and SI was verified at 25% [(74.00 (25.83m)], 50% [(148.10 (51.66m)] and 87.5% [(259.15 (90.41m)] of the TLimvVO(2)max duration. These data showed a reduction of the propelling efficiency throughout such a test. These findings could be useful when designing training programmes, namely of middle distance swimmers, taking into consideration maximum aerobic speed, time to exhaustion and propelling efficiency.