Speed and acceleration are major skills required to excel at many sports, and coaches are constantly looking for ways to improve. But the banes of competitive athletes are always looming – overtraining and injury. A recent study from Brigham Young University investigated the effect of a high-speed treadmill used in conjunction with a bodyweight support system on female soccer players’ 40-yard sprint time, as well as max isometric knee flexor and extensor strength.
There were 39 subjects who began the study, but only 32 completed the entire 6-week protocol. The 39 female participants played either for youth accelerated soccer or high school soccer teams. Each player was tested to determine baseline figures for 40-yard dash times, as well as for isometric knee extensor and flexor strength.1
Knee flexor and extensor strengths were measured using a strain gauge. The knee flexor isometric strength test was done in a prone position, with the knees at a 45-degree angle. The extensor isometric test was done in a seated position with the knee flexed to 90-degrees. The subjects were encouraged to flex or extend their knee as hard as they could for 5 seconds with a 1 minute rest period between the two trials.2
Each participant was then was randomly placed into one of 3 groups:
- 13 subjects participated in a group that ran on a high-speed treadmill with a bodyweight support system (BWS).
- 11 subjects used a standard treadmill with no bodyweight support system.
- 8 subjects did not participate in a sports acceleration program and did not alter their exercise routines outside of the study.
The BWS used was a harnessing system that consisted of an unweighting station, cable bar and assembly, control panel, and a harness vest, which lifted approximately 10% of the subject’s bodyweight using an air compressor.
The participants who were in the sports acceleration program groups attended 2 training sessions a week for 6 weeks (in addition to their normal soccer practices). The sports acceleration program sessions consisted of a 12-session program that included: warm-up, 9 ladder drills, 36 5-second plyometric/agility dot drills (single and double leg), isometric lumbar extension strengthening exercises, bosu-ball planking (side planks, pushups, and starfish sit-ups), lateral resistor band drills, medicine ball sit-ups chest press, single and double leg plyometric training, and a 12-minute workout on the treadmill (which included a 2-minute warm-up). There was a series of 3 treadmill training routines repeated by both experimental groups throughout the 6-week training program.3
The results of study demonstrated greater increases in ability in the standard treadmill group with no BWS and the high-speed with BWS group, compared to that of the control group. It is worth mentioning that the standard treadmill group outperformed other two groups. The knee extensor strengths did not show any significant differences between treatment groups and control group. On the flip side, despite performance increases, the participants in the standard treadmill group had a much higher rate of shin splints (66%) and foot pain throughout the duration of the study compared to those in the high-speed treadmill (8%) and control group (0%). So while training with the BWS did not increase performance as much as training without it, it did decrease rate of injury.4
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