Biomedical subjects

G A Valiant

Publications and source records attributed to G A Valiant.

3 recordsLinked to original sources

PubMed1995

Tibial shock measured with bone and skin mounted transducers.

The purpose of this study was to assess the value of superficial transducer mounting to measure tibial shock during locomotion. Surface (SMT) and bone mounted transducers (BMT) simultaneously recorded axial tibial acceleration in five subjects who ran at 4.5 m s-1. SMT produced inconsistent recording across the subjects both in the time and frequency domains. In two subjects, SMT signals provided close approximation of BMT signals, some distortion occurred in one subject while severe distortions were observed in the other two subjects. The present results established that SMT could not be used directly to quantify the shock transmitted through the tibia during running. However, frequency transformation of SMT recordings produced encouraging results; the transformed SMT signals mimicked the signals recorded with the bone mounted transducer.

Acceleration↗

PubMed1993

Friction--slipping--traction.

The minimum translational traction requirements of outsoles for shoes used for walking, running, and activities involving lateral movements are presented. Since it will be shown that the classical friction relationships described by Coulomb do not always apply to the elastomeric materials used in modern day athletic footwear, empirical measures of the traction characteristics of candidate materials and designs must be made. A physical traction testing device has been developed to make measurements of the traction characteristics of shoe outsoles will be described. This device quantifies both translational and rotational traction characteristics. Examples of factors affecting both of these variables are presented. Combining a knowledge of the traction characteristics of materials and designs and the factors influencing traction with knowledge of the traction requirements of different activities permits the matching of appropriate outsoles to shoes used for specific activities.

Biomechanical Phenomena↗

PubMed1982

The effects of immobilization and of electrical stimulation on muscle glycogen and myofibrillar ATPase.

This study observed biochemical changes that occur when an athlete's limb is immobilized for six weeks, and determined if electrical stimulation could alter any of these changes. A control group (n = 3) and a stimulation group (n = 6) who had undergone major knee surgery, consented to a series of muscle biopsies of the vastus lateralis muscle. Both groups engaged in standard rehabilitative procedures following cast removal. The stimulation group's therapy also consisted of electrical stimulation (f = 2500 Hz.) of the quadricep group. The results indicate that ATPase activity decreased in the control group during the immobilization period (from 0.321 +/- 0.095 mumoles Pi/mg./min. to 0.205 +/- 0.032 mumoles Pi/mg./min.) but not in the stimulation group (from 0.268 +/- 0.022 mumoles Pi/mg./min. to 0.296 +/- 0.073 mumoles Pi/mg./min.), p less than 0.05. The stimulation did not appear to have any effect on glycogen concentrations. It is suggested that electrical stimulation retards the decrements in biochemical characteristics of human muscle due to immobilization.

Adenosine Triphosphatases↗