Jim D. Whitley

Relationships between Individual Differences in Strength, Speed, and Mass in an Arm Movement

Abstract According to physics, the equation F = 2 md/t 2 determines the force F required to move a mass m through a distance d in t seconds. Two experiments were performed on college men (n = 35 and 30) in which a lateral arm movement of approximately 90 deg. involving about 4 ft. of hand travel, was made at maximum speed. The movement time t, the effective arm mass m, and the static dynamometer strength s of the muscles were measured for each subject. The reliability of individual differences in all measures was above .96. There was no significant correlation between static strength and “strength in action” computed from arm mass and speed of movement. The results agree with the concept that strength as ordinarily measured is determined by a neuromotor coordination pattern rather than the ultimate physiological capacity of the muscle. The neuromotor pattern energizing the muscle is different during movement. Absence of correlation is another example of the high specificity of neuromotor coordination skil...

Effects of Practice Distribution on Learning a Fine Motor Task

Abstract Sixty college men were given 35 trials of either distributed practice (DP) or massed practice (MP) (N = 30 per group) on a fine motor learning task, the foot tracking task. The study was designed to make a direct comparison between the two groups of the amount learned. While learning was significant for both groups, there was no difference in the amount learned between groups. As expected, performance was significantly better under DP; this was attributed to the temporary depressant effects of Ir resulting from MP. The present results are in general agreement with the findings of a number of recent learning studies on gross motor tasks; almost without exception they reported that practice distribution affected performance but not learning. Thus, the traditionally accepted belief that DP is superior to MP in motor learning is not supported by experimental evidence. These findings present practical implications for motor learning in terms of efficiency in the use of practice time.

Influence of Three Different Training Programs on Strength and Speed of a Limb Movement

Abstract The experiment was designed to compare the effects of isometric-isotonic (A), dynamic-overload (B), and free swing (C) exercise programs on the speed and strength of a lateral arm movement The 26 college men in each group—three experimental and one control—were given pre- and post-training speed and strength trials. Each experimental group performed its assigned exercise twice a week during the 10-week training period. Reliability coefficients for both strength and speed of movement measurements were found to be high. Following training there were significant speed increases in both the isometric-isotonic and dynamic-overload groups (t=10.06 and 8.10; however, the difference in speed gain between conditions was nonsignificant (F=.10). Also, strength increases in both of these groups were significant (t=8.81 and 3.08), with that of the isometric-isotonic group significantly greater than the dynamic-overload group (F=5.11). No significant speed or strength gains were registered by either the free s...

Learning Component in Repetitive Maximal Static Contractions

60 college men were given 12 trials on an unfamiliar and fairly complex test of static strength in a single testing period. 30 were allowed 1½ min. of rest between trials and the rest 3 min. It was hypothesized that individuals can learn how to exert force statically, i.e., significantly improve their strength scores, during practice on a test that requires the neuro-muscular integration of several muscle groups not commonly tested for strength. A second hypothesis was that there would be no difference in the amount learned between groups with 1½-min. and 3-min. rests. Results supported both hypotheses. The reliability of individual differences in learning scores was moderately high; r = .56 for single trials and .61 for a 2-trial average. Thus, individuals can learn how to exert force statically in an unfamiliar and fairly complex strength test and the influence of this learning effect can be determined, providing possible facilitative effects of training and inhibitory effects of fatigue are minimized.

Velocity Curves and Static Strength-Action Strength Correlations in Relation to the Mass Moved by the Arm

Abstract Tests were made with the hand carrying weights of 0.2, 3.1, and 16.6 kg. during a 72° horizontal adductive arm swing of maximal speed timed at 12° intervals. Five practice swings and 20 trials, under each condition, were performed by 60 male subjects. Reliability coefficients were high. The first 24° of movement exhibited declining acceleration, followed by linearly increasing acceleration for the 24°—60° interval and deceleration for the next 12°. Compared with static strength in the movement position, action strength computed from acceleration was much greater with the heaviest weight and considerably less with the light weights. The correlation between static strength and speed was quite low for the normal arm swing but increased with added weight, becoming r = .76 for the heaviest. There was little correlation of individual differences in speed between different phases of movement or between movements with light and heavy weights. Specificity was high, although correlations were made for atte...

Relation between Muscular Force of a Limb, under Different Starting Conditions, and Speed of Movement

Abstract A horizontal adductive arm swing executed at maximal speed, and timed at intervals of 15°, 53°, 90°, and 105°, was studied under two experimental conditions. Although the movement completed was the same in both conditions, the fundamental difference between the “normal” and “pre-tensed” arm movements was that in the latter condition the subject built up his arm strength maximally just prior to initiating the movement. Twenty trials under each condition was performed by 60 college men. All reliability coefficients were found to be high, i.e., over .89. In contradiction to expectations, the relationship between premovement strength and speed of movement at the first station (r = -.208) was lower than anticipated. However, the low correlations found between strength and speed of movement are in general agreement with the results of earlier investigators which have substantiated the predominance of neuromotor specificity.

Faster Reaction Time through Increasing Intent to Respond

The RT of 50 college men was measured under normal (N) and artificial (E) limb mass conditions. It was hypothesized that RT in condition E would be significantly faster than in N because the heavier mass would encourage a stronger conscious and willful intent, during the response foreperiod, to trigger the simple learned RT response stored in the memory motor drum. The results (t = 4.202, p < .05) substantiated this hypothesis. Even though the relationship of RTs in N and E conditions was moderately large (r = .56), the specificity was very high, 69%; thus the possibility that two separate neuromotor programs are involved cannot be excluded. It is concluded that in a simple RT experiment the creation of a situation during the response foreperiod which increases Ss conscious and willful intent to respond, will result in a faster RT. Also, the results support the known specificity of individual differences in performance of simple discrete motor acts.

Effects of increasing inertial resistance on performance and learning of a training task.

Abstract Ninety college men were assigned to one of three control-resistance conditions to determine the effects of artifically increased mass (moment of inertia) on performance and learning of a continuous rotational-type fine motor tracking task. All subjects performed the first 25 trials under their respective conditions: (C), intermediate mass (E-1), and heavy mass (E-2); after a 5-min. rest all groups completed the last 10 trials under control conditions. While the pretest performance of E-2 was significantly depressed compared with C and E-1, and significant learning occurred within each groups, there was no difference in the amount learned among groups. There was little relationship between static strength (measured on the tracking leg in the movement position) and either performance or learning scores. Also, there were no changes in strength performance either within or among groups. The belief that effective motor learning depends on so called “optimal conditions” was seriously questioned.

A New Motor Learning Task: The Foot-Twist Tracking Task

Abstract Sixty college men were tested on a new motor learning task: the foot-twist tracking task. They were given 35 one-min. trials; each consisted of 30 sec. of work followed by 30 sec. of rest. A 5-min. rest period was interpolated between trials 25 and 26 to allow for the dissipation of reactive inhibition accrued during prerest performance. The results supported the expectation that practice on the new task would result in significant amounts of learning. However, the improvement in performance, while fairly large (21%), is substantially less than that found on the pursuit rotor and other large muscle motor coordination tasks. The expectation of reliable learning scores is also supported by the present results (r = .77). This learning reliability is relatively high when compared with those obtained on other large muscle motor learning tasks.

A Test of Activation as a General Factor in Strength Performance.

Abstract A test was made of the general activation concept as it relates to strength performance. No difference in grip strength was found between an experimental group (N = 35), who performed maximal leg strength exercises between grip trials (in an attempt to raise their level of activation through induced muscular tension), and a control group (N = 35) who read between grip trials. Also, there was no difference in grip strength performance over trials for both groups. Intercorrelations of strength scores between limbs for the experimental group showed more specificity than generality. While these results fail to support a generalized activation effect in the static strength performance context, they do provide additional evidence of neuromuscular specificity in motor ability.