## 4 Discussion  
The 3-Hop and to a lesser extent the 5-Hop are movements that provide physiotherapists, as well as strength and conditioning coaches and technical coaches, with valuable insights into neuromuscular function. Improving understanding around the utility of these jumps and their associated measures provided an overarching focus for this research. Specifically the aims of this study were threefold: (1) to examine the relationship between 3-Hop and 5-Hop distance and sprint performance, and to determine whether hop kinetic variables provide stronger relationships to sprinting ability than kinematic/hop distances; (2) to explore the relationship between two methods of determining 3-Hop and 5-Hop \(\text{RSI}_{\text{hor}}\) and sprint performance; (3) to investigate whether the 5-Hop/3-Hop ratio or \(\text{RSI}_{\text{hor}}\) and other kinetic measures could differentiate between sprinters of different ability. The main findings were as follows: (1) 3-Hop and 5-Hop distances were strongly correlated with 10, 20, and 40 m sprint times (\(r=0.70\) to 0.80), while the relationship between the kinetic measures and sprint times was weak to moderate (\(r<-0.55\)); (2) the strength of the association between \(\text{RSI}_{\text{hor}}\) and sprint performance increased with sprint distance (\(r=0.49\) to 0.71; \(p<0.001\)), and \(\text{RSI}_{\text{hor}}\) calculated from jump distance was a stronger predictor of sprint performance than calculation from flight time; (3) hop ratios did not differentiate between fast and slow sprimters, whereas \(\text{RSI}_{\text{hor}}\) was able to; (4) there were significant differences in some kinetic measures of 3-Hop and 5-Hop tests that differentiated fast and slow sprimters; and (5) given the small differences between the 3-Hop and 5-Hop results, there would seem little value in including both hops in the assessment of sprint-related performance. The 3-Hop and 5-Hop distances were strongly correlated with 10, 20, and 40 m sprint times (\(r=0.70\) to 0.80), with the strength of association increasing with sprint distance. The results of this study were consistent with the previously reported relationships between multiple hop distances and sprint performance, both for recreational (\(r=0.68\) to 0.86) athletes [8,10] and sub-elite (\(r=0.84\) to 0.89) sprimters [7]. [PERSON] et al. (2006) [9] proposed that predictions of sprint performance using horizontal jump measures might be more effective for athletes involved in sports requiring a wide range of sprinting expressions, but less applicable for competitive-level sprimters. They also suggested that more sensitive measures, such as force and power, might provide a better reflection of what occurs during sprint running compared to jumping distance alone. Our findings in this cohort of sportsmen suggests that while kinetic variables can explain some of the variance associated with sprinting, they were not strong predictors of sprint performance in this cohort. The general relationships between the hop GRFs and sprint performance were weak to moderate (\(r<-0.55\)). The maximal vertical forces seen in both 3-Hop and 5-Hop tests were shown to have the strongest relationship with sprint performance, and the strength of this relationship increased with sprinting distance over 5 m to 45 m. This finding was consistent with previously reported characteristics of performance in elite sprimters [28]. Of interest was the relationship between the two methods of calculating 3-Hop and 5-Hop \(\text{RSI}_{\text{hor}}\) and their relationship to sprint performance. The strength of the association between \(\text{RSI}_{\text{hor}}\) and sprint performance increased with sprint distance (\(r=0.49\) to 0.71; \(p<0.001\)), with \(\text{RSI}_{\text{hor}}\) calculated from jump distance showing a stronger correlation with sprint performance than when calculated from flight time (see Figure 2). [PERSON] et al.