Biomedical subjects

R D Rochelle

Publications and source records attributed to R D Rochelle.

4 recordsLinked to original sources

PubMed1997

Identification and correlation of human footfall load parameters using multivariate analysis.

This research had two main objectives: to identify and quantify the multiple reaction parameters of human footfall load histories for 24 subjects; and to seek statistical correlations of the reaction parameters with two gaits: fitness walking and running, with two footfall surfaces: rigid and mat, and with two subject attributes: gender and arch index. These reaction parameters, measured with a force plate, include the subjects' foot reaction forces in the three orthogonal directions and the particular features of these forces such as their duration, average values, peak values, and rates of loading. An automated data retrieval-software system evaluated these reaction parameters. The statistical correlations were made using principal component analysis (PCA), a method that projected the 13 identified footfall reaction parameters onto subsets of three or four parameters called principal components that contained most of the variance of the original thirteen. The results, among others, show couplings between the vertical and the peak medial load, but an uncoupling of the posterior-anterior loads with the loads in the other two directions.

Adult↗

PubMed1981

Physiologic response to endurance work as a function of prior exercise.

Five male subjects performed an endurance task (ET) following 20 min of prior exercise (PE) at work loads corresponding to approximately 30%, 45%, 60% and 75% of VO2 max. There was a 1-min rest interval between the PE and ET. The ET consisted of 10 min of walking at a speed and slope corresponding to 75% of VO2 max after which time the speed was increased by 10 m/min each minute until the subject could no longer continue. Although endurance performance was not significantly influenced by the PE-30 and PE-45, performance following PE-60 and PE-75 was significantly impaired, as was the peak VO2 attained at the end of the ET. Although O2 deficits at the beginning of the ET were reduced by the higher intensities of PE, the plasma lactate levels at the 8th min of the ET were not significantly lower under those conditions since those levels of PE led to some lactate accumulation during the PE itself. VO2 during the last 5 min of the constant load part of the ET was similar in all conditions but PE-75, during which it was higher. It is suggested that although PE might be useful for tasks in which the initial work loads are maximal or supramaximal with respect to VO2, it is of questionable value in endurance tasks that begin at a high but submaximal intensity.

Adult↗

PubMed1978

Thermoregulation in surfers and nonsurfers immersed in cold water.

During immersion to the neck in 19 +/- 0.6 degrees C water, surfers maintained higher toe temperatures than nonsurfers. The Lewis hunting response was seen only in the toes of the surfers. The shivering response of the surfers occurred later and was of lesser intensity. Threefold increases in metabolic heat production (140 kcal/m2-h) above rest level were found in both groups. Rectal temperature changes were similar in both groups, with a mean decline of 1.2 degrees C over the 1-h exposure period. Individual changes in rectal temperature were negatively correlated to percent of body fat. An initial hyperventilation upon immersion was followed first by a decline and then by a rise to three times that of rest. A transient rise in heart rate (35 beats/min) occurred in the initial stage of immersion in both groups and subsequently fell to basal levels, rising slightly thereafter. Sinus arrhythmias were observed during the first few minutes of immersion. In nonsurfers, plasma cortisol approximated the decrease anticipated because of the circadian cycle but was elevated in the surfers. Plasma volume decreased 12.2% (surfers) and 17.6% (nonsurfers). Diuresis was observed in both groups, and was 3.2 and 5.0 ml/min for surfers and nonsurfers, respectively.

Adaptation, Physiological↗

PubMed1977

Hypothermia in the aged.

Body temperature is maintained by a balance between heat production and heat loss. Temperature regulation consequent to exposure to a cold environment appears to be modified in elderly persons. An evaluation of the physiological adjustments made by older individuals is presented. It is apparent that hypothermia can develop in the older population as a consequence of modifications in both behavioral and physiological responses to cold exposure. With the growing awareness of an energy shortage with consequent lower ambient temperatures in homes, there is a need to obtain adequate information as to the physiological capabilities and adaptive potential of elderly individuals to a cold stress.

Aging↗