Effect of Sled Towing on Sprinting Performance Research Paper Example

Sprinting speed is a vital and valuable aspect of any field or track sport. One of many goals a coach has for their athlete is enhancing running speed, especially the acceleration phase. For field sports and track competition, the ability to rapidly produce high sprint velocity for a short or long distance horizontally, acceleration, is the determining factor of success. There are many different training methods to increase acceleration: unresisted sport-specific sprinting, weight-training, plyometric training, flexibility training, and resisted sprint training. However, the latter is shown through literature to enhance acceleration time. Specifically with sled towing. Thus, examining the enhancements sled towing has on sprinting speed, specifically acceleration, during heavy and light loads, is essential to understand why implementing sled-pulling in a speed training program is favorable.

Overview of Sled Towing

Sled towing is a form of resisted sprint training where an athlete is attached to the sled through a harness on their chest or waist and performs a series of sprints with specific weight on the sled (Petrakos et al., 2016; Lockie et al., 2003; as cited in Pantoja et al., 2018). The significant components of sled towing are the use of the mass of the sled and the friction between the sled and ground surface to generate horizontal force and external resistance to sprinting (Cronin et al., 2006; Spinks et al., 2007, as cited in Kawamori et al., 2014). Since better acceleration performance is associated with the exertion of a great power horizontally, studies on the effects of sled towing are increasing due to the workings of the resisted training method (Harris et al., 2008; Zafeiridis et al., 2005, as cited in Martínez-Valencia et al., 2015). Thus, the following will focus on the force production during acceleration and the effects of heavy and light loads on sprint acceleration. 

Force Output

During acceleration, there are many force outputs and relationships involved that are critical components of acceleration ability. The force-velocity and power-velocity relationship during the acceleration phase relies on three variables: theoretical maximal force (F0), theoretical maximal velocity (V0), and maximal power (Pmax), which correspond to maximal capabilities of the lower limbs to produce such force, velocity, and power (Pantoja et al., 2018). The relationship between these variables can inform coaches of an athlete’s skills and if there are imbalances. Of which, sled towing could provide and improve an athlete’s application and abilities of force, velocity, and power (Pantoja et al., 2018). Another force output critical to acceleration ability is the rate of force production (RFP). According to Essentials of Next-Generation Sports Speed Training, RFP is an athlete’s ability to generate force as quickly as possible (Dintiman, 2020). In which resistant sprint training, sled towing, can potentially increase RFP due to the rapidly developing power of the lower limbs increasing with sled pulling (Martínez-Valencia et al., 2015). Though literature and research have shown potential benefits between sled-towing and force output, the critical issue is how heavy and light loads impact sprint acceleration performance. 

Heavy Loads

Many coaches use the 10% rule, loading up to 10% body mass, due to the belief that applying a load above 10% of an athlete’s body mass will alter sprint mechanics excessively and the possible deterioration of sprint mechanics and performance under unresisted sprints (Alcaraz et al., 2009; Lockie et al., 2003, as cited in Kawamori et al., 2014). However, current research suggests that applying heavy loading while sled towing will increase force production output, thus improving sprint acceleration. For instance, a study by Pantoja et al. (2018) on weighted sled pulling effects on sprinting found that the technical ability of force application is enhanced when load increases, and the RF-V relationship is more effective with heavier loads at the beginning of the acceleration phase. These results strengthen the notion of using heavily loaded sled towing to improve sprint acceleration speed since the force application is directed horizontally (Pantoja et al., 2018).  Also, Kawamori et al. (2014) studied the effects of light loads and heavy loads on sprint acceleration ability. They found that both loads improved 5- and 10-m sprint respectively, thus questioning the 10% rule and showcasing the benefits of heavily loaded sled pulling (Kawamori et al., 2014). Though there are benefits to sled towing heavy loads, light loads showed benefits when comparing the two. 

Light Loads

A study by Martínez-Valencia and colleagues (2015) on sled towing and sprint performance found a decreased sprint performance over 20- and 30-m when loads increased. These results showcase that using heavier loads when sprinting long distances is not as beneficial as using lighter loads due to decreased sprint performance. Another study by Kawamori and colleagues (2014) showed that lighter loads had little impact on resultant and vertical impulses at 8-m from pre- to posttraining. In contrast, resultant and vertical notions of heavier loads were significantly higher (Kawamori et al., 2014). The increase in vertical impulses with heavier loads rather than horizontal impulses could argue against using heavy sled pulling for enhancing acceleration than light sled towing. Lastly, Pantoja et al. (2018) also found that towing heavy loads reduced the effectiveness of applying ground force in a horizontal direction, DRX. Also, Morin et al. (2012, as cited in Pantoja et al., 2018) found a significant correlation between the DRX index and sprint performance when investigating the mechanical determinants of sprinting 100-m. Therefore, suggesting training with a determined load before heavy loading will aid an athlete to limit the decrease in RF and improve the application of force (Pantoja et al., 2018). Thus, these studies showcase the benefits of light-loaded sled towing on sprint performance compared to heavier loads.

Conclusion

Overall, sled towing is a form of resistant sprint training associated with enhanced sprint acceleration due to it generating horizontal force, an essential factor for acceleration speed. Thus,  recent research has investigated the correlation between force output and sled towing and the effects light vs. heavy loads have. Force output and relationships are critical for acceleration speed, and sled pulling could increase the application of force, velocity, power, and applied rate of force production, RFP. In addition, Current research suggests that heavier loads provide more benefits than once perceived with increases in force application horizontally and improvement in 5- and 10-m sprints. However, studies have also found that heavier loads decrease speed performance in 20- and 30-m sprints, vertical impulses are higher than with light loads, and the decrease in the effectiveness of applying ground force in a horizontal direction is more significant in heavy than light loads. Therefore, implementing sled towing in a speed training program is advantageous due to enhanced sprint acceleration and positive effects of both heavy and light-loaded towing based on current research.