Title

Quadriceps femoris echo intensity and muscle thickness as independent predictors of athleticism in middle-school boys

Document Type

Presentation

Journal/Book Title/Conference

National Strength and Conditioning Association 2016 National Conference

Publisher

National Strength and Conditioning Association

Location

New Orleans, LA

Publication Date

7-7-2016

Abstract

Previous studies have demonstrated that quadriceps femoris echo intensity and muscle thickness are moderately correlated with measures of muscle function in young and old adults. PURPOSE: The purpose of this study was to examine the potential for vastus lateralis (VL) and rectus femoris (RF) echo intensity and muscle thickness to be used as independent predictors of athleticism in middle-school boys. METHODS: Twenty-nine middle-school aged boys (mean ± SD age = 12 ± 1 years; mass = 45.8 ±13.2 kg; height = 156.2 ± 10.8 cm) participated in this study. All subjects were engaged in their middle school’s physical education program and had participated in at least one sport program during the previous year, but none were actively engaged in a structured exercise program. Ultrasound measurements were performed on the right VL and RF. The subjects performed maximal isometric strength testing of the right leg extensors, maximal countermovement vertical jumps, as well as maximal 20 meter sprint and 5-10-5 agility assessments. Torquetime curves were used to calculate rate of torque development (RTD) values at 200ms from torque onset. Fifteen bivariate correlations were performed to examine Pearson r values between the three independent variables (quadriceps femoris echo intensity, VL muscle thickness, and RF muscle thickness) and each of the dependent variables (RTD200, countermovement jump height, peak jump velocity, sprint speed, and agility). Partial correlations were utilized to examine these relationships while removing the influence of body mass and age. Stepwise multiple regression analyses were performed to determine the contributions of the ultrasonography variables, age, and mass on each of the dependent variables. RESULTS: Table 1 displays bivariate and partial correlation matrices for the relationships among the variables. Stepwise regression analyses indicated that quadriceps femoris echo intensity was the sole predictor of vertical jump height (R2 = .254, F = 9.91, P = .005), peak jump velocity (R2 = .149, F = 4.74, P = .038), and agility (R2 = .273, F = 10.14, P = .004). Interestingly, both VL (R2 = .307, F = 11.98, P = .002) and RF (R2 = .418, F = 19.39, P < .001) muscle thickness were found to be the lone predictors of agility. Furthermore, RF muscle thickness was also found to be the only predictor of peak jump velocity (R2 = .241, F = 8.57, P = .007). CONCLUSION: Echo intensity and muscle thickness were significantly correlated with several athletic assessments even when age and mass were accounted for. RF muscle thickness was a stronger predictor of peak velocity, sprint speed, and agility than both quadriceps femoris echo intensity and VL muscle thickness. Overall, echo intensity and muscle thickness showed the strongest relationships with agility and sprint speed. PRACTICAL APPLICATIONS: With a growing interest in youth athletics, ultrasound imaging may become a non-invasive, easy-to-use tool to predict success in sports

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