Relationship between agility, sprint, power and strength according to different age groups in youth soccer players

The aim of the study is the investigation of the relationship between agility, sprint, power and strength according to different age groups. Youth soccer players aged 15 (U15), 16 (U16), 17 (U17) and 18 (U18) who were playing in one of the teams in Spor Toto League were randomly recruited to the study. "505 agility test" was used to evaluate agility, 20 meter sprint and flying 20 meter sprint tests were used for sprint ability. Squad and counter movement jump tests were used to assess the power of participants. Peak isokinetic concentric knee extension and flexion measured in two different speed (600sec-1 and 1800sec-1) for each right and left leg. A strong correlation was detected between the agility and 600sec-1 right knee extension strength in U15 (r=-0.619; p=0.004), and also between agility and 1800sec-1 left knee flexion (r=0.526; p=0.028) in U17. No significant relation was detected between agility and strength in U16 and U18 (p>0.05). There was no significant relationship between agility and sprint in all age groups (p>0.05). A significant correlation between the indicators of power (active and squad Gmax) and agility was observed only in U18 (r=-0.509; p=0.031 and r=-0.474; p=0.047 respectively). Except U15, a significant correlation was observed in all age groups between sprint (20 m sprint test) and strength (600sec-1 and 1800sec-1 extension test). The correlation of sprint and 600sec-1 right knee extension was high (r=-0.664; p=0.002) whereas the correlation was also prominent (r=-0.554; p=0.014) between sprint and 1800sec-1 right knee extension in U16. The correlation ratio of sprint and 600sec-1 left knee extension was r=-0.543; p=0.020, whereas it was r=-0.562; p=0.015 between sprint and 1800sec-1 right knee extension in U17, The correlation ratio of sprint and 600sec-1 right flexion was r=-0.490; p=0.39 in U18. There was no significant relationship between strength and flying 20 sprint in U15 and U18 (p>0.05). A significant correlation between the indicators of agility and strength (600sn-1 right extension, 600sn-1 right flexion and 1800sn-1 left flexion) was observed only in U16 (r=-0.491; p=0.033, r=-0.683; p=0.001 and r=-0.544; p=0.016 respectively). The correlation ratio of flying 20 m sprint and 600sec-1 right extension was r=-0.802; p=.000, 600sec-1 right flexion was r=-0.700; p=0.001, 1800sec-1 right extension was r=-0.858; p=0.000, 1800sec-1 right flexion was r=-0.569; p=,014, 1800sec-1 left extension was r=-0.669; p=0.002 and 1800sec-1 left flexion was r=-0.518; p=0.028 in U17. There was no significant relationship among squat, counter movement jump, 20 m sprint and flying 20 m sprint in U15 and U16 age groups (p>0.05). A significant correlation between squad and the sprint quality indicators (20 m and flying 20m) was observed in U17 (r=-0.666; p=0.003 and r=-0.781; p=0.000 respectively), a significant correlation between counter movement jump and the sprint quality indicators (20 m and flying 20m) was observed in U17 (r=-0.702; p=0.001 and r=-0.729; p=0.001 respectively), a significant correlation between squad jump Gmax and the sprint quality indicators (20 m and flying 20m) was observed in U17 (r=-0.581; p=0.011 and r=-0.852; p=0.000 respectively), a significant correlation between counter movement jump Gmax and the sprint quality indicators (20 m and flying 20m) was observed in U17 (r=-0.632; p=0.005 and r=-0.870; p=0.000 respectively). There was only one significant relationship between counter movement jump and 20 m sprint (r=-0.489; p=0.040) in U18. There was no significant relationship between isokinetic knee strength and squad jump in U15 and U18 age groups (p>0.05). The correlation ratio of squad jump and 1800sec-1 right knee extension was r=0.475; p=0.040 in U16, The correlation ratio of squad jump and 600sec-1 right extension was (r=0.492; p=0.040), whereas they were r=0.570; p=0.013 between 1800sec-1 right extension and squad power, and r=0.513; p=0.030 between 1800sec-1 right flexion and squad power in U17 There was no significant relationship between counter movement jump and isokinetic strength in U15 and U16 (p>0.05). A significant correlation between 1800sec-1 right extension and counter movement jump was observed only in U17 (r=0.508; p=0.031). A significant correlation between 600sec-1 right extension and counter movement jump was observed only in U18 (r=0.557; p=0.016). There was no significant relationship between squad Gmaks and isokinetic strength in U15 (p>0.05). The correlation ratio between the squad Gmaks and 600sec-1 left extension was r=- 0.594; p=0,007, and it was r=0.570; p=0.036 for the 600sec-1 left flexion and it was r=0.482; p=0.036 for the 1800sec-1 right flexion in U16. The correlation ratios between the squad Gmaks and 600sec-1 right extension, 600sec-1 right flexion, 600sec-1 left flexion, 1800sec-1 right extension, 1800sec-1 right flexion were r=-0.670; r=0.649; r=0.554 r=-0.559; r=0.716; r=0.627; r=0.429 (p=0.002; p=0.004; p=0.020; p=0.016; p=0.001 p=0.005; p=0.036) respectively in U17. The correlation ratios between the squad Gmaks and 600sec-1 left extension, 600sec-1 right flexion, 600sec-1 left flexion, 1800sec-1 right extension, 1800sec-1 right flexion were r=0.539; r=0.537; r=0.475; r=0.503 r=0.647 (p=0.021; p=0.022; p=0.046; p=0.033; p=0.004) respectively in U18. The correlation ratio between the counter movement jump Gmax and 1800sec-1 left extension was (r=0.520; p=0.019), whereas it was r=0.486; p=0.030 between 1800sec-1 left extension in U15. The correlation ratios between the counter movement jump Gmax and 600sec-1 left extension, 600sec-1 left flexion, 1800sec-1 right flexion were r=0.575; r=0.619; r=0.619 (p=0.010; p=0.005; p=0.005) respectively in U16. The correlation ratios between the squad Gmaks and 600sec-1 right extension, 600sec-1 right flexion, 600sec-1 left extension, 600sec-1 left flexion, 1800sec-1 right extension, 1800sec-1 right flexion, 1800sec-1 left flexion were r=0.662; r=0.570; r=0.537; r=0.490; r=0.717; r=0.578; r=0.487 (p=0.003; p=0.013; p=0.021; p=0.039; p=0.001; p=0.012; p=0.041) respectively in U17. The correlation ratios between the counter movement jump Gmaks and 600sec-1 right extension, 600sec-1 right flexion, 1800sec-1 right extension, 1800sec-1 right flexion were r=0.541; r=0.582; r=0.508; r=0.688 (p=0.020; p=0.011; p=0.031; p=0.002) respectively in U18. In conclusion, a strong relationship between sprint, agility, power and strength was observed in our study, nevertheless, its intensity and significance changes according to age. Key Words: Youth soccer, agility, sprint, power, strength, age