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Biomedical subjects

C A Putnam

Publications and source records attributed to C A Putnam.

8 recordsLinked to original sources
PubMed1993

Sequential motions of body segments in striking and throwing skills: descriptions and explanations.

The motions of segments participating in striking and throwing skills are generally sequenced in a proximal-to-distal fashion. These sequences are often described in terms of the linear velocities of the segment endpoints, joint angular velocities or segment angular velocities. While each method of description has its own merit, the latter is recommended since it leads to an intuitively pleasing way of explaining segment motions. Explanations of segment motion sequences are dependent not only on a knowledge of the joint moments driving the system of linked segments, but on the way the segments interact as functions of their motions and orientations. The motion-dependent interaction among segments is significant and offers an explanation of the sequencing of segment motions. As illustrated by the thigh and lower leg in kicking and by the upper arm and forearm in overarm pitching, the forward acceleration of the proximal segment plays a large role in causing the distal segment to lag behind. The subsequent forward acceleration of the distal segment is largely a result of the way the proximal segment interacts with the distal segment as a function of the proximal segment's angular velocity. The proximal segment is subsequently slowed down largely due to the motion-dependent effect of the distal segment on the proximal segment. Differences in the way segments interact in striking and throwing skills can account for variations in the timing of segment actions and these differences need to be examined before establishing general principles governing striking and throwing.

Biomechanical Phenomena↗
PubMed1991

A segment interaction analysis of proximal-to-distal sequential segment motion patterns.

The purpose of this study was to examine the motion-dependent interaction between adjacent lower extremity segments during the actions of kicking and the swing phases of running and walking. This was done to help explain the proximal-to-distal sequential pattern of segment motions typically observed in these activities and to evaluate general biomechanical principles used to explain this motion pattern. High speed film data were collected for four subjects performing each skill. Equations were derived which expressed the interaction between segments in terms of resultant joint moments at the hip and knee and several interactive moments which were functions of gravitational forces or kinematic variables. The angular motion-dependent interaction between the thigh and leg was found to play a significant role in determining the sequential segment motion patterns observed in all three activities. The general nature of this interaction was consistent across all three movements except during phases in which there were large differences in the knee angle. Support was found for the principle of summation of segment speeds, whereas no support was found for the principle of summation of force or for general statements concerning the effect of negative thigh acceleration on positive leg acceleration. The roles played by resultant joint moments in producing the observed segment motion sequences are discussed.

Biomechanical Phenomena↗
PubMed1987

Factors influencing the angular velocity of a human limb segment.

The angular velocity of a knee extension performed after flexion with different range and velocity, i.e. the kicking movement with stabilized thigh, was investigated and described. In addition, the maximum velocity of extension reached after prestretch was compared to that obtained in trials without prestretch. The maximum velocity of extension varied from 213 to 1087 degrees s-1 depending on the range and velocity of prestretch. In trials without prestretch the velocity of extension was worse up to 43% when small range of movement was involved. In trials with full range of movement the velocity of extension was similar in the tasks with and without prestretch. In this context the possible role of elastic energy is discussed. The method used was electrogoniometry.

Adult↗
PubMed1979

Forces exerted during exercises on the uneven bars.

The purposes of this study were (1) to develop a technique to measure the force exerted on uneven bars during a gymnast's performance, and (2) to determine the magnitudes of the maximum forces exerted on the bars during normal use. Strain gages, a UV recorder, and motion-picture cameras were used to record the forces exerted against the bars and the motions with which they were associated. Three college gymnasts were used as subjects. Each performed several repetitions of an exercise sequence judged to result in the maximum loading of the bars she might produce under normal conditions. The maximum forces recorded were 3500 N (low bar) and 2140 N (high bar). These values were recorded during a sharp impact between the subject's thighs and the bar during the passage of the subject beneath the bar in a giant swing, respectively. Making due allowance for possible measurement error and for the estimated effects of the bars being used by gymnasts of greater mass than those in this study, it was concluded that bars should be designed to withstand repeated loads of at least 4205 N.

Adult↗
PubMed1979

A mathematical model of hiking positions in a sailing dinghy.

A mathematical model of the human body designed to calculate the resultant muscle torques required at the hip and knee joints for specific hiking techniques is presented. Data for the model were obtained from ten male subjects who adopted three basic positions: Position 1 with the knees located at the inside edge of the sidedeck, Position 2 with the knees at the middle of the sidedeck, and Position 3 with the knees at the outside edge of the sidedeck. Each resultant muscle torque was expressed as a percentage of each subject's maximum voluntary hip flexion or knee extension torque. It was found that where Positions 1 and 2 were equally effective in keeping the boat upright, Position 2 was superior to Position 1 in regard to the per cent of maximum muscle torque required. The superiority of Position 2 over Position 3 depended on the individual's relative muscle strength at the hip and knee joints. The stronger the hip flexors with respect to the knee estensors, the more desirable was Position 2 and vice versa.

Biomechanical Phenomena↗