Ball, T. E., Massey, B. H., Misner, J. E., McKeown, B. C., & Lohman, T. G. (1992). The relative contribution of strength and physique to running and jumping performance of boys 7-11. The Journal of Sports Medicine and Physical Fitness, 31, 364-371.

Boys (N = 6) ranging in ages from 7 through 11 years were measured on the following independent variables:

• Static strength - thigh extension, leg extension, and plantar flexion, back lift, leg lift, and left and right grips.
• Body composition - estimated fat from triceps, subscapular, and calf skinfolds, and fat-free body weight estimated from potassium-40 measures.
• Body structure - skeletal widths, and segment girths, lengths, and volumes.

The dependent variables were vertical jump, standing broad jump, 50-yard dash, 600-yard run, and mile run.

Strength measures increased the variance accounted for from 10 to 23% over that when body size, composition, and structure were used alone.

There were no obvious relationships between the independent and dependent variables. This reflects the individual/specific nature of each activity "despite the fact that three of the variables are running performances and two are jumps." (p. 369). Although statistically significant results were obtained, in practical terms the amount of association between variables was very small. None of the relationships was strong enough to suggest using the measures as a diagnostic tool or for exercise prescription.

Implication. In boys, strength and body composition, structure, and physique only have a low relationship with a variety of running and jumping performances. The specific nature of the revealed relationships for each activity suggests that it would be ill-founded to predict performance from one activity to another. Strength has a very minor roll to play in some of the activities while it is not related to vertical jumping. Body and strength factors are not particularly important for the performance of boys 7-11 years of age in running and jumping.

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