Perceptual and Motor Shills, 1979,48, 1022. @ Perceptual and Motor Skills 1979
STRENGTH A N D SPEED RELATIONSHIPS HELEN M. ECKERT University o f Californi4 Berkeley
It has been postulated that the relationship between strength and speed of movement in a task conforms to the formula I; = ma: where F represents maximal available force; m, the mass of the body part or projectile moved; and a, the acceleration or speed of movement around a joint (Eckert, 1965). Force analysis of data by Whitley and Smith (1963) shows a much higher force cornponent ( F = 2450) in a task where a correlation of .73 is reported between strength and speed of arm movement than the .37 correlation for the low force task ( F = 564). Adding 18-lb. weights to increase the mass of vertical jumpers resulted in a reduction in angular degrees per second 'of 649 to 592 at the hip, 915 to 859 at the knee, and 1074 to 980 at the ankle (Eckert, 1968). Jackson and Frankiewicz ( 1975), in a factor analysis of 16 muscular strength tests, isolated two factors with static leg-strength tests and variables that involved moving the body through space. The residual scores transformations in this study held mass constant so that force would equal acceleration; the investigators concluded this relationship would be consistent with Newton's second law of motion. The equivocal nature of correlational analyses of strength and speed may, perhaps, be accounted for by the nature of the statistic and the narure of the relationship between mass and velocity of muscular contraction as reported by Hill (1938) which is similar to that of F = ma where the force is constant. Using quick release of the knee, Fenn, et al. ( 1931) found that subjects maintained different levels, but parallel, force curves. The correlation coefficient is based upon two dimensions and may, therefore, be a questionable statistic for assessing the relationship between strength and speed of movement for tasks which do not use maximal force. REFERENCES ECKERT. H. M. A concept of force-energy in human movement. Jordmal o f American Physical Education Therapy Association, 1965, 45, 213-218. ECKERT. H. M. T h e effect of added weights o n joint actions in the vertical jump. Research Quarterly, 1968, 39, 943-947. FENN, W. O., BRODY,H., & PETRILLT,A. T h e tension developed by human muscles at different velocities of shortening. American Journal o f Physiology, 1931, 97, 1-14. HILL,A. V. T h e heat of shortening and the dynamic constants of muscle. Proceedings o f the Royal Society (Biology), 1938, 126, 136-195. JACKSON, A. S., & FRANKIEWICZ, R. J. Factorial expressions of muscular strength. Research Quarter!y, 1975, 46, 206-217. WHITLEY, J. D., & SMITH, L E. Velocity curves and static strength-action strength correlations in relation to the mass moved by the arm. Research Quarterly, 1963, 34, 379-395. Accepted May 15, 1979.
STRENGTH A N D SPEED RELATIONSHIPS HELEN M. ECKERT University o f Californi4 Berkeley
It has been postulated that the relationship between strength and speed of movement in a task conforms to the formula I; = ma: where F represents maximal available force; m, the mass of the body part or projectile moved; and a, the acceleration or speed of movement around a joint (Eckert, 1965). Force analysis of data by Whitley and Smith (1963) shows a much higher force cornponent ( F = 2450) in a task where a correlation of .73 is reported between strength and speed of arm movement than the .37 correlation for the low force task ( F = 564). Adding 18-lb. weights to increase the mass of vertical jumpers resulted in a reduction in angular degrees per second 'of 649 to 592 at the hip, 915 to 859 at the knee, and 1074 to 980 at the ankle (Eckert, 1968). Jackson and Frankiewicz ( 1975), in a factor analysis of 16 muscular strength tests, isolated two factors with static leg-strength tests and variables that involved moving the body through space. The residual scores transformations in this study held mass constant so that force would equal acceleration; the investigators concluded this relationship would be consistent with Newton's second law of motion. The equivocal nature of correlational analyses of strength and speed may, perhaps, be accounted for by the nature of the statistic and the narure of the relationship between mass and velocity of muscular contraction as reported by Hill (1938) which is similar to that of F = ma where the force is constant. Using quick release of the knee, Fenn, et al. ( 1931) found that subjects maintained different levels, but parallel, force curves. The correlation coefficient is based upon two dimensions and may, therefore, be a questionable statistic for assessing the relationship between strength and speed of movement for tasks which do not use maximal force. REFERENCES ECKERT. H. M. A concept of force-energy in human movement. Jordmal o f American Physical Education Therapy Association, 1965, 45, 213-218. ECKERT. H. M. T h e effect of added weights o n joint actions in the vertical jump. Research Quarterly, 1968, 39, 943-947. FENN, W. O., BRODY,H., & PETRILLT,A. T h e tension developed by human muscles at different velocities of shortening. American Journal o f Physiology, 1931, 97, 1-14. HILL,A. V. T h e heat of shortening and the dynamic constants of muscle. Proceedings o f the Royal Society (Biology), 1938, 126, 136-195. JACKSON, A. S., & FRANKIEWICZ, R. J. Factorial expressions of muscular strength. Research Quarter!y, 1975, 46, 206-217. WHITLEY, J. D., & SMITH, L E. Velocity curves and static strength-action strength correlations in relation to the mass moved by the arm. Research Quarterly, 1963, 34, 379-395. Accepted May 15, 1979.
