The effect of different external cues on the ability of young athletes to generate force, velocity and power

Verbal cues are essential tools for practitioners developing a young athlete’s motor skill abilities. External cues have been shown to optimize athletic performance and movement competency in adults with some limited data suggesting the same is true for children. Developing physical qualities is a common goal for practitioners working with young athletes, including strength and conditioning coaches, sports coaches, and physical education teachers. Force, power, and velocity characteristics may be of particular importance, given their contribution to many physical activities. However, very little is understood in respect of how external cues influence the ability of young athletes to produce force, power and velocity. Review work in Chapters 2 and 3 suggested measures of force, power and velocity can be accurately measured in youth, and that both adults and children can respond favourably to external cues in tasks which require high levels of force, power or velocity to be produced. Chapters 4, 5, 6, and 7 provide novel empirical investigations on the effects of different external cues across exercise tests that assess force, velocity, and power characteristics.

Results from Chapter 4 showed that all external cues provided a specific response during a drop jump (DJ); a contact-specific cue reduced ground contact time (GCT) and increased reactive strength index (RSI), a height-specific cue increased jump height and a quiet-specific cue reduced outcomes associated with injury risk. Thus the findings demonstrate that responses of young football players to an external cue are specific to the type of cue provided. Whereas, the results of Chapter 5 showed non-significant, trivial-to-small (g < 0.20 – 0.59) effects with the use of 4 different external cues on the force-velocity profiles of young trained sprinters during a 30 m sprint. Conversely, Chapter 6 indicated that cue type had limited effects on outcomes in the IMTP, or unloaded and loaded squat jumps, with mostly trivial (g < 0.20), non-significant differences (p> 0.05) across kinetic variables. However, significant (p < 0.05) and cue-specific small to large effects (g = 0.33 – 1.52) were observed in the CMJ and DJ. Thus, results suggest cues have more effect in vertically orientated tasks with increasing movement velocity. Consequently, practitioners working with adolescent athletes should consider both the type of exercise and the desired outcome when providing external cues.

Chapter 7 demonstrated that height and contact time cues elicited specific kinetic responses that were significantly different to other conditions (p < 0.05); the height cue increasing impulses (d = 1.17 – 1.21), and jump height (d = 0.68), with the contact cue shortening GCT (d = 1.27), increasing vertical stiffness (d = 1.48) and increasing force (d = 1.20 – 1.36). When combining the height and contact cue, a combination of significant (p < 0.05) kinetic responses were also observed, albeit to a lesser effect. Specifically, the combined cue increased impulse (d = 0.71 – 0.76) and jump height (d = 0.57) compared to a contact cue; and when compared to a height cue, increased RSI (d = 0.34), force (d = 0.69 – 0.83) and vertical stiffness (d = 0.75) while also reducing GCT (d = 0.69). Practitioners working with well-trained adolescent athletes can utilize different external cues to effectively influence the kinetic strategies employed during a DJ.