Kinematic, strength, and stiffness adaptations after a short-term sled towing training in athletes.

One of the most frequently used methods for training the sprint-specific strength is the sled towing. To date, no studies have been conducted to explore the effects of this method after a training period in well-trained athletes. The purpose of this study was to determine the effects of 4 weeks of resisted sprint training with sled towing. Twenty-two trained athletes experienced in the use of weighted sled (WS) participated in the study. They conducted the same 3-week training to level their initial condition. After that they were distributed in two groups, unresisted (UR) and WS training. They carried out the same 4-week, 2 days/week sprint-specific training, only differing in that the experimental group performed sprints with a (WS) which caused a reduction of 7.5% of their maximum velocity. Pre- and posttest were conducted which included the measurement of sprint kinematics, muscular strength (including isoinertial, isokinetic, and jump measurements), and sprinting stiffness (leg and vertical). Results show different adaptations in the groups although no interaction effect was found. The WS group improved the velocity in the transition phase, while the UR group improved the velocity in the maximum velocity phase. No improvements in the height of the jump tests were found.