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.

Evaluation of muscle fatigue during 100-m front crawl

“…It is possible that as the duration of the active phase of LD2 (significantly) and TB (only tendency towards the change, P = 0.11) prolonged inside one cycle, it presented the prolongation of non-activation time for PM1 and PM2. Other authors (Seifert et al 2004(Seifert et al , 2007Seifert and Chollet 2008;Alberty et al 2008) used the kinematics to obtain data on arm coordination, so our results are not directly comparable to theirs. However, some common points can be outlined.…”

“…Seifert et al (2007) obtained similar results for the high-velocity male swimmers: the relative duration of the propulsive phase of the stroke was longer in the first lap with respect to the last lap, and the opposite results (the relative duration of the propulsive phase of the stroke was shorter) for the middle-and low-velocity swimmers. The increase of the relative propulsive (push and pull) phase occurring during fatiguing swim was also reported by Alberty et al (2008Alberty et al ( , 2005. It is possible that to maintain a stable stroke length in spite of accumulating fatigue, the swimmers extended the gliding phase of the stroke, which led to extension of the nonactive phase for the muscles and possibly also induced some changes in the arm coordination.…”

“…and Komi 1993;Weiss et al 1988). Swimmers often compensate for the decrease in SL with a higher stroke rate (SR) to maintain the velocity (Alberty et al 2008), but as the fatigue progresses the stroke rate and, consequently, the swimming velocity both diminish as well. Some authors have found that the relative duration of the non-propulsive phase within a stroke is reduced with respect to the propulsive phase with progressive fatigue, which reflects in changed arm coordination (Alberty et al 2008;Seifert et al 2007).…”

“…Fatigue during swimming has been widely examined by monitoring different physiological, kinematic and biomechanical parameters such as swimming velocity, acceleration, stroke length, stroke rate, arm coordination, spatiotemporal parameters (such as 3-D fingertip pattern), mechanical power output, (net) energy cost, heart rate, oxygen consumption, blood lactate concentration and the isometric force (Alberty et al 2008;Aujouannet et al 2006;Billat et al 1996;Bonifazi et al1993;Dekerle et al 2005;Fernandes et al 2006;Rouard et al 1997;Seifert et al 2005Seifert et al , 2007Tella et al 2008;Toussaint et al 2006). All these studies demonstrate that development of muscle fatigue during swimming is an interesting topic, which can be studied using various methods and parameters.…”

Stroking Characteristics during Time to Exhaustion Tests

“…In swimming, this corresponds to the inability to sustain the imposed pace. During such constant speed swims, a progressive increase in the SR value with a concomitant decrease in SL has been observed to keep the imposed pace (2,9,16,31). Such adaptations have been attributed to fatigue development, a tired swimmer being gradually unable to produce the force necessary to overcome resistance to forward movement.…”