Practical application of the simplified model to assess the arm stroke efficiency: a tool for swimming coaches

In a simplified way, the front crawl arm propelling efficiency (ηp) can be estimated using the distance between the shoulder and the hand at the end of the pull phase, the swimming speed (v) and the stroke rate (SR). The aim of this study was to verify the $$\eta p$$ηp and kinematical parameters along the 200 m front crawl test (T200), to provide comprehension about $$\eta p$$ηp with easy accessibility and applicability to swimming coaches. Eleven male swimmers (18.1 ± 2.9 years old) participated in this study. T200 was performed (25 m long pool) and recorded with two-dimensional video system. Performance in T200 was 129.7 ± 2.8 s. Mean values of $$\eta p$$ηp, SR, stroke length (SL) and v were obtained from the T200 eight laps. Along the laps, $$\eta p$$ηp (38.6 ± 1.1%) varied from 40.5 (Lap 1) to 37.2% (Lap 5) and v (1.52 ± 0.09 m·s−1) varied from 1.42 (Lap 7) to 1.65 m·s−1 (Lap 1). There was a medium effect size of the eight laps over the $$\eta p$$ηp. Throughout T200, ηp, SR and SL showed slight variations, while v was highest in the first two laps. The simplified way to estimate ηp seems to be a quick and useful tool for coaches and swimmers.