Strength training has the potential to improve sprint performance and running economy in athletes[1,2], but it is uncertain whether it is the increase in maximum strength per se or other factors affected by strength training which accounts for these findings. Therefore, the aim of this study was to investigate the relationship between strength in leg extensors, measured as one repetition maximum (1 RM) in squat, and sprint abilities as well as running economy in professional soccer players. METHODS: Fifteen professional Norwegian soccer players (±SD) age 25±5 years, height 184±5 cm, weight 77.3±7.8 kg and maximal oxygen uptake 64.2±5.0 ml·kg-1·min-1 (range: 56.4-71.4 ml·kg-1·min-1) were tested for 1 RM in half squat, sprinting performance (0-40m) and running economy, measured while running on 5.5% incline at 10 km/h. RESULTS: The 1 RM in half squat was 149.2 ±17.3 kg (range: 100-180kg), 10m sprint time was 1.78±0.06 sec, 30-40 meter sprint time was 1.16±0.05sec and total sprint time (0-40m) was 5.37±0.16sec. Relative strength in half squat (1RM/body weight) was correlated with both 10m acceleration (r=0.70) and total time on the 40m sprint (r=0.75). Running economy was 47.2±0.6 ml·kg-1·min-1 (range: 0,265-0,303). Relative strength in half squat was not correlated with running economy (r=0.16). DISCUSSION: The results of this study confirm that relative strength is important for performance in activities like sprint where athletes accelerate their own body weight [1]. Earlier studies [2,3] has indicated that an increase in 1RM increase running economy. However, in the present study running economy was not correlated with 1RM. This might indicate that maximal strength per se is not important for running economy. It may be that the rate of force development (RFD) and muscle-tendon stiffness are more important for running economy than maximum strength. A tight musculo-tendinous system, and consequently a higher degree of stiffness, may be advantageous for running economy and strength training has been reported to increase muscle-tendon stiffness [4]. In conclusion, our results confirm that relative strength in leg extensors is important for the performance in sprint, but no relation was found between relative strength and running economy.
© Copyright 2009 14th annual Congress of the European College of Sport Science, Oslo/Norway, June 24-27, 2009, Book of Abstracts. Veröffentlicht von The Norwegian School of Sport Sciences. Alle Rechte vorbehalten.