Response synergies over a single leg when it is perturbed during the complex rhythmic movement of pedalling.

Previous studies report that perturbing the posture of humans evokes specific patterns of muscular synergies in the legs. This study investigated the pattern of muscular responses of a whole limb when it was rapidly perturbed in the phase of extending during stationary pedalling. Subjects were instructed to resist.

A multivariate solution for cyclic data, applied in modelling locomotor forces.

The variability in dependent biological data (measured as forces at the human foot during pedalling) was reduced, by principal components analysis, to two major components which, combined, accounted for 46% of the variability observed in sets of 26 observations per cycle. On the basis of weightings over the cycle, the components were interpreted as due to Power Production and to Phase Switch from power-generation to recovery. Force measurements were made for three frequencies of leg pedalling (1.

Human group I excitatory projections from ankle dorsiflexors to quadriceps muscle.

A short latency projection of group I afferent fibers from ankle dorsiflexors to knee extensor muscles has been categorized as species specific to humans. However, the effects of the pathway have only been inferred from conditioning homonymous reflexes in relaxed muscle. This study focused directly on the responses evoked in the electromyogram of the heteronymous muscles when active, in two experiments.

Magnitude of the H reflex of the soleus substantially exceeds the myotatic response from rapid dorsiflexion of the ankle joint.

We compared the magnitude of short-latency EMG responses in the soleus after electrical stimulation and after muscle stretch. The peak to peak amplitudes and areas of such stretch-evoked responses, following initial rotation velocities to 200 degrees/s, did not extend beyond the lower part of the H reflex range (evoked electrically). The disparity suggests caution in the use of electrical stimulation of group 1 afferent fibers when a study is to be made of normal human movement.

Locomotor limb synergism through short latency afferent links.

Reports of facilitation of lower limb synergists through afferent stimulation in resting humans lead to study of short latency reflex responses during activity of the legs. Four synergistic muscles of the right leg were examined following electrical stimulation of low threshold afferents of the posterior tibial (PTN) and femoral (FN) nerves. Four males cycled on an ergometer with pedals modified to measure the force applied.

A note on stability in force applied to control a repetitive task with the legs.

The forces applied to pedals during cycling were collected every 40 ms from approximately 29,000 movement repetitions. Intra-cycle mean values of force and its variability were significantly correlated, supporting Schmidt's impulse variability theory of within-movement activities of the legs. In addition, as mean forces approached peak values, coefficients of variation decreased.

Between-minute stability in habituated human skill with modestly lowered blood glucose.

Modestly lowered blood glucose (G) occurs with fasting and exercise, increasing variability in forces applied during repetitions of an habituated cycling task. Its effect was studied on stability of the movement cycle pattern of forces from minute to minute. Forces applied at 26 positions in the movement cycle were correlated with each other over 20 one minute samples.

Repetitive skill deterioration with fast and exercise-lowered blood glucose.

Using a computerized system for measurement of the variability of force exerted at 26 points in each pedal revolution during the repetitive habituated task of cycling, healthy adult males 6 times performed for 20 minutes, either (a) 3 hours after a meal (fasting) or when so fasted and then fed glucose (b) immediately before, or (c) 30 minutes before performance. Both light and moderate workloads were used. As expected, blood glucose concentrations fell modestly below basal with exercise under (a) or (c) but not under (b).

Diet, physiological work and accident incidence of forge workers.

Three experiments were made to study the following three factors in forge workers in a hot shop: (a) the metabolic load of daily work, (b) dietary intake, and (c) the effect of supplementing morning dietary intake with glucose syrup ingestion upon accident incidence. High energy output, mean 9.7 MJ (2,300 kcal), complemented high energy intake, mean 15 MJ (3,600 kcal), a shortage of intake in the morning being compensated for after work in the evening.

Bimodal relationship of human tremor and shivering on introduction to cold exposure.

Four subjects were exposed to an environmental challenge of -12 degrees C for 15 min in four conditions of exposure: 1) clothed body and clothed arm, 0.5 clo units: 2) clothed body and exposed arm, 0.4 col; 3) exposed body and exposed arm, 0.

Hormonal and cardiac response of autistic children to changes in environmental stimulation.

A study was made of physiological responses of autistic children to variations in environmental load in order to examine the under- versus over-arousal dichotomy. More specifically, measures of urinary mucoprotein excretion and mean heart rate and three measures of heart rate variability were compared with matched controls in conditions of normal, high, and low total environmental load. The results suggest that, although behaviorally unresponsive, the autistic children responded physiologically, were generally in a lower state of arousal than the control group, and were labile in response to changes in stimulation.

Fenoprofen therapy in large-joint osteoarthritis: double-blind comparison with aspirin and longterm experience.

This study, designed to evaluate fenoprofen in patients with osteoarthritis, consisted of two phases: I. A double-blind crossover comparison of fenoprofen, 200 to 600 mg every six hours, to aspirin, 325 to 975 mg every six hours; II. Longterm use of fenoprofen in an open study design.