François Potdevin

Changes in swimming technique during time to exhaustion at freely chosen and controlled stroke rates

Abstract The aim of this study was to assess technical changes during constrained swimming in time-to-exhaustion tests. Ten swimmers of national standard performed a maximal 400-m front crawl and two sets of exhaustion tests at 95%, 100%, and 110% of mean 400-m speed. In the first set (free), swimmers had to maintain their speeds until exhaustion and mean stroke rate was recorded for each test. In the second set (controlled), the same speed and individual corresponding stroke rate were imposed. The durations of the exhaustion tests, relative durations of the stroke phases, and arm coordination were analysed. For each speed in the “controlled” set, the exhaustion tests were shorter. Moreover, variables were consistent, suggesting a stabilization of stroke technique. Under the free condition, stroke rate increased to compensate for the decrease in stroke length. At the same time, swimmers reduced the relative duration of their non-propulsive phases in favour of the propulsive phases. Thus, swimmers changed their arm coordination, which came close to an opposition mode. These two constraints enable swimmers both to maintain their stroking characteristics and develop compensatory mechanisms to maintain speed. Moreover, stroke rate can be seen as a useful tool for controlling arm technique during paced exercise.

Effect of stroke rate reduction on swimming technique during paced exercise.

Alberty, MR, Potdevin, FP, Dekerle, J, Pelayo, PP, and Sidney, MC. Effect of stroke rate reduction on swimming technique during paced exercise. J Strength Cond Res 25(2): 392-397, 2011-The purpose of this study is to analyze the acute adaptations of motor organization subsequent to a reduction in spontaneous stroke rate (SR) at different swimming speeds, a task constraint that is currently used by trainers to improve stroke technique. Ten well-trained swimmers (8 males and 2 females, whose mean swimming speed on a 400-m front crawl stroke represents 76.8 ± 3.7% and 73.3 ± 2.7% of the mean speed of the short-course pool world record, respectively) performed 3 sets of 3 time to exhaustion trials in front crawl at paces corresponding to 95%, 100%, and 110% of the mean speed measured in a 400-m race. During the first set, individual SR was continuously recorded and averaged. During the second set (Fixed), participants were constrained to swim at their individual corresponding SR. For the third set (Lowered), an individual corresponding SR value lowered by 5% was imposed. Durations of trials and arm stroke phases durations were analyzed. The results showed that the durations of the whole trials declined significantly from the Fixed set to the Lowered set (p < 0.05). Swimmers spent more time in the nonpropulsive phases (increases ranged from 8.6-13.2%; p < 0.05), and the duration of the propulsive phases did not differ significantly in the lowered set. The significant decline in exercise durations might have been caused by an unusual muscular solicitation. Swimming technique changes during trials in the Fixed set suggest an increase in magnitude and efficiency in the propulsive force and a better body streamlining to limit an increase of the resistive impulse in between arm propelling actions. In conclusion, these results should be taken into account to better define training-set technical benefits and better include the impact of such task constraints into the training schedule.

What is the best swimming stroke to master for beginners in water safety tests

The aim of this study was to ascertain whether performance in a series of water safety tests, in clothed and swimsuit conditions, were dependent on the swim stroke that beginners selected for traversing maximal distance. A total of 45 children (9.6 ± 1.6 years) involved in a learning programme were asked to complete six tests to: travel their maximal distance in water; hold a vertical position; float on their back for as long as possible; perform a maximal number of rotations from front to back in 10 seconds; complete their deepest immersion dive; and perform a final integrated test composed of the previous tasks that were successfully executed in isolation. Pupils were divided into three groups according to the swim stroke they had selected for the first test. The results revealed that the breaststroke group was less affected by wearing clothes in performance on the maximal distance and the final integration test, and was able to tread water for a longer period of time. The backstroke group maintained a horizontal position on their backs for a longer period of time, and was able to rotate position more frequently from front to back. No effect of preferred swim stroke was noted in the maximal immersion dive test. Overall, the front crawl group was most affected by wearing clothes when traversing a maximal distance, floating on their back and performing the final integrated test. Findings suggested that breaststroke and backstroke may be more important to teach beginners for performance in water safety tests.