Background: Maximal muscle strength and body proportions are some of the key attributes to be a fast swimmer. Even though dolphin kick (DK) has become essential to be a fast swimmer little is known of its associations to muscle strength and body proportions. Moreover, the effect of feet size has been stated to be a primary contributor to dolphin kick thrust production, but scientific evidence is still scarce.

Aim: The aim of this study was to examine the correlation between lower extremity muscle strength, abdominal strength and feet length with dolphin kick performance over 15 meters in active competitive swimmers 15-20 years old

Method: Twelve Test subjects (six male and six female) participated. Test subjects performed four 15 meters dolphin kick trials. Lower extremity muscle strength was tested with a three repetition maximum strength test and abdominal strength with brutal bench test. The muscles tested were rectus femoris, biceps femoris and rectus abdominis. Feet length was measured with a measuring tape. The correlations between lower extremity strength, abdominal strength and feet length with dolphin kick performance were calculated with spearman’s correlation.

Results: Twelve test subjects between ages 15-20 years old participated. Spearman correlation test showed that lower extremity strength (rectus femoris: rs=-0.57 and biceps femoris: rs=-0.66) had a large association with dolphin kick performance. Abdominal strength (rs=-0.46) and feet length (rs=-0.35) had a moderate association with dolphin kick performance.

Conclusion: The present study conclude that lower extremity strength is important for DK performance over 15 meters and that abdominal strength and feet length also is important but is less associated to it. The finding from this study can be used for making training programs for improving DK performance and for scouting swimmers with beneficial traits for specific swimming technique.