In the modern day sprint training is the most common method in the new age of sports training, to enhance the ability of an athlete to run at optimum speed, sprint training must be an essential part of an athlete’s training regime (McKenna, M et al, 1997). As equipment advanced so did training methods, therefore to improve performance a certain amount of resistance was added to further enhance an athlete’s performance therefore improving an athlete’s overall speed this was named “Resisted Sprint Training” (RST) is defined by Alexander 1989 as running at top velocity while resistance forces work in the opposite direction. There is countless ways of applying an opposing force; weighted clothing, sleds containing weights, parachutes with different surface areas and common hills are all used to counter act the sprints being undertaken by the athlete. Due to the research that has gone into this area of RST it has provided coaches with more options to experiment and implement with their athlete. The author of this review will be analysing literature and research into sled training commonly shortened to ST and whether the common usage of this in a training programme is an effective method to improve certain variables such as acceleration, maximum velocity, force application and finally stride length/frequency. As RST is a popular method for most modern day sports people from low to elite levels, it has an uncertain concluding factor as to the links to improve sprint kinematics.

(Faccioni, 1994a) “The benefits of the use of resisted sprint running is that it recruits more muscle fibers, requires more neural activation” therefore due to this quote the effects of ST have been probed and primed for many years, especially the way the way it influenced the acceleration on track athletes. After completing a study using males taking part in resistance using 10% plus of the participants body mass, a decrease in stride frequency and stride length was evident, while performing the tests other visual physiological differences were evident such as increased muscle flexibility especially in regards to the hip flexors. When concluding their findings in 1994 they found that when carrying a heavier load. Stress was evident on the participants body therefore hampering the test, this is why a lower weight was used to improve acceleration when using ST for RST.

Murphy et al 2003 study was establishing the load for sprint training with sled towing in the maximum velocity phase. 12 athletes participated in the study. They ran 30 m flying sprints, an unloaded sprint and sprints pulling loads of 6%, 10%, and 15% of their body mass, on a synthetic track surface wearing spikes, they found that this equitation lets coaches and strength trainers to calculate the load for resisted sprint training with sled towing due to the increase in Mean maximum velocity, 30-m sprint time. These findings support another study that was done in 2004 by LeBlanc, J. S.et al who studied the comparisons and differences between free sprint training and resisted in relation to the key attributes of sprinting in the top phase of the athletes speed. Both results show significant differences and shows signs towards ST being beneficial for sprinters top speed phase.

When looking at the literature published the main area of study which has been evident is whether ST increased maximum speed and overall acceleration Hansen, K. T.et al (2006).found that RST with 8% body mass sled towing for 4 week improves transition performance (16-31 m), while traditional sprint training improves performance in the maximum velocity phase (31-51 m) in elite athletes.

In contrast to improving overall acceleration and maximum speed studies have been done to improve sprint specific strength Ettema, G. J. C. (2006) et al stated that RST does improve this evidently in the lower body being the legs and lower back, having this strength is always going to beneficial due to the strength of the lower limbs. The way this evaluation was concluded was down to using and comparing a weighted belt for the athlete to wear, a parachute to provided resistance to the athlete and finally the sled to be able to place weights on to provide a resisted force when completed 30 metre flying sprints. It became evident that the sled training was best for developing maximum sprint strength, however the literature contradicts itself when talking about biomechanical properties which could affect the athletes speed therefore further biomechanical analysis needs to be undertaken to provide a coach with exact biomechanical movements to fully utilise the ST.

After researching the literature which is available to get a good insight into ST, when talking about biomechanical influences in the ST, the practioners should be using 3D analysis software to enable them to have a clear view of the correct posture and movements in each phase especially when the athlete is being specific to stride length, stride frequency and velocity also as other areas in the forever changing world, further research will give myself a better and broader insight into the ability of ST in relation to RST. Putting a focus into the specifics of each ST session such as sets and repetitions of the training being undertaken this therefore would need to client specific as previously stated the weight of each ST is set to a fix rate, however increasing this could either have a positive or negative effect on success and sustainability. When focusing on the suggested correct amounts of training when concerning sets and reps, no previous research has actually indicated a set number to work from. This is why variation and expert analysis needs to be scrutinised to enable a benchmark to be set for initial improvement.

References

Alexander, M.J.L. The relationship between muscle strength and sprint kinematics in elite sprinters. Can. J. Sport Sci. 14:148–157. 1989.

Cronin, J. B., and Hansen, K. T. (2006). Resisted sprint training for the acceleration phase of sprinting. Strength Cond. J., 28, 42-51

Faccioni, A. (1994a). Assisted and resisted methods for speed development: Part 1 Modern Athlete & Coach, 32, 3-6.

Kristensen, G. O., van den Tillaar, R., and Ettema, G. J. C. (2006). Velocity specificity in early-phase sprint training. J. Strength Cond. Res., 20, 833-837

LeBlanc, J. S., & Gervais, P. L. (2004). Kinematics of assisted and resisted sprinting as compared tonormal free sprinting in trained athletes. Proceedings of the 22th International Symposium onBiomechanics in Sport, Ottawa, Canada 536.

Lockie, R. G., Murphy, A. J., and Spinks, C. D. (2003). Effects of resisted sled towing on sprint Kinematics in field-sport atlethes. J. Strength Cond. Res., 17, 760-767.

McKenna, M. J., G. J. F. Heigenhauser, R. S. McKelvie, J. D.MacDougall, and N. L. Jones. Sprint training enhances ionic regulation during intense exercise in men. J. Physiol. (Lond.) 501: 687–702, 1997

Murphy, A. J., Lockie, R. G., and Coutts, A. (2003). Kinematic determination of early acceleration in field sport athletes. J. Sports Sci. Med., 2, 144-150.