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Biomedical subjects

L G Pugh

Publications and source records attributed to L G Pugh.

At least 19 recordsLinked to original sources
PubMed1977

Skin temperature during running--a study using infra-red colour thermography.

Infra-red colour thermography has been used to visualize skin temperatures in two athletes standing and running in an outdoor environment at 20 degrees C and in a climatic chamber at 11 degrees C. Temperature distributions and changes have been recorded on film and analysed. Mean skin temperatures determined by this method have been compared with skin temperatures obtained with a probe thermocouple. During running, skin temperatures were higher over muscles than over other structures and the distribution differed dramatically from that observed before exercise. Regional mean skin temperatures obtained by thermography differed by up to 4 degrees C from those obtained with the thermocouple probe. Overall mean skin temperatures obtained by both methods agreed to within 1-5 degrees C.

Adult↗
PubMed1975

Haematological status of middle- and long-distance runners.

1. Haematological investigation and blood volume measurements were carried out on forty male middle and long distance runners and twelve non-athletes. 2. The distribution of haemoglobin concentration, packed cell volume, erythrocyte count, total ironbinding capacity, serum and erythrocyte folate and serum vitamin B12 concentrations were essentially the same in atheletes and non-athletes. The mean serum iron concentration was higher in non-athletes than in athletes. There was no difference in the above measurements between athletes taking iron and/or folate and athletes not taking these supplements. 3. Blood volume and total body haemoglogin were on average 20% higher in the atheletes than in the non-athletes. 4. There was no correlation between haemoglobin concentration and blood volume in athletes. The evidence of this study suggests that haemoglobin concentration and blood volume are independently controlled. 5. 2,3-Diphosphoglycerate concentration in the erythrocytes was higher in the athletes than in the non-athletes; the mean values were 15-9 and 14-2 mumol/g of haemoglobin respectively.

Adult↗
PubMed1974

The relation of oxygen intake and speed in competition cycling and comparative observations on the bicycle ergometer.

1. The relation of V(O2) and speed was determined on six competition cyclists riding at speeds ranging from 12 km/hr to 41 km/hr on the runway of an airfield. Comparative measurements were made on the bicycle ergometer to determine the corresponding work rates, and from this information rolling resistance and air resistance were derived.2. V(O2) was a curvilinear function of cycling speed, and increased from 0.88 l./min at 12.5 km/hr to 5.12 l./min at 41 km/hr, mean body weight being 72.9 kg.3. On the ergometer, V(O2) was a linear function of work rate; maximum values up to 5.1 l./min (74.4 ml./kg min) and work rates up to 425 W (2600 kg m/min) were observed.4. Data are presented on the relation of pedal frequency and speed in cycling, and on the relation of mechanical efficiency and pedal frequency, as determined on the ergometer.5. The estimated rolling resistance for four subjects was 0.71 kg f. The drag coefficient was 0.79 and the drag area 0.33 m(2). The values agreed well with results obtained by other methods.6. The energy expenditure (power developed) in cycling increased approximately as the square of the speed, and not as the cube of the speed as expected. This was explained by the varying contribution of rolling resistance and air resistance to over-all resistance to motion at different speeds.

Adult↗
PubMed1971

The influence of wind resistance in running and walking and the mechanical efficiency of work against horizontal or vertical forces.

1. O(2) intakes were determined on subjects running and walking at various constant speeds, (a) against wind of up to 18.5 m/sec (37 knots) in velocity, and (b) on gradients ranging from 2 to 8%.2. In running and walking against wind, O(2) intakes increased as the square of wind velocity.3. In running on gradients the relation of O(2) intake and lifting work was linear and independent of speed. In walking on gradients the relation was linear at work rates above 300 kg m/min, but curvilinear at lower work rates.4. In a 65 kg athlete running at 4.45 m/sec (marathon speed) V(O2) increased from 3.0 l./min with minimal wind to 5.0 l./min at a wind velocity of 18.5 m/sec. The corresponding values for a 75 kg subject walking at 1.25 m/sec were 0.8 l./min with minimal wind and 3.1 l./min at a wind velocity of 18.5 m/sec.5. Direct measurements of wind pressure on shapes of similar area to one of the subjects yielded higher values than those predicted from the relation of wind velocity and lifting work at equal O(2) intakes. Horizontal work against wind was more efficient than vertical work against gravity.6. The energy cost of overcoming air resistance in track running may be 7.5% of the total energy cost at middle distance speed and 13% at sprint speed. Running 1 m behind another runner virtually eliminated air resistance and reduced V(O2) by 6.5% at middle distance speed.

Adult↗
PubMed1970

Oxygen intake in track and treadmill running with observations on the effect of air resistance.

1. The relation of V(O2) and speed was measured on seven athletes running on a cinder track and an all-weather track. The results were compared with similar observations on four athletes running on a treadmill.2. In treadmill running the relation was linear and the zero intercept coincided with resting V(O2).3. In track running the relation was curvilinear, but was adequately represented by a linear regression over a range of speeds extending from 8.0 km/hr (2.2 m/sec) to 21.5 km/hr (6.0 m/sec). The slope of this line was substantially steeper than the regression line slope for treadmill running.4. The influence of air resistance in running was estimated from measurements of V(O2) on a subject running on a treadmill at constant speed against wind of varying velocity.5. The extra O(2) intake (DeltaV(O2)) associated with wind increased as the square of wind velocity. If wind velocity and running velocity are equal, as in running on a track in calm air, DeltaV(O2) will increase as the cube of velocity.6. It was estimated that the energy cost of overcoming air resistance in track running is about 8% of total energy cost at 21.5 km/hr (5000 m races) and 16% for sprinting 100 m in 10.0 sec.

Adult↗
PubMed1969

Thermal, metabolic, blood, and circulatory adjustments in prolonged outdoor exercise.

Thermal, metabolic, and circulatory responses were studied in six hill-walkers taking part in a 28-mile (45-km.) walk in rough country in autumn and winter, air temperatures being 6 to 12 degrees C. and -2 to 2 degrees C., respectively.Though they were an apparently well-matched party, the walkers had to split into three pairs to avoid exhaustion. They adjusted their clothing so that mean skin temperatures were similar in both warm and cold conditions, the average value being 30.5 degrees C. compared with the resting comfort range of 33 to 34.5 degrees C. When, on the winter trial, skin temperatures were lowered by reduction of clothing, mean skin temperatures fell to 26.5 to 27.8 degrees C., one subject showing a value of 21.3 degrees C. These temperatures were associated with moderate discomfort from cold.Gut temperatures during exercise, measured with a radio pill, averaged 38.7 to 37.9 degrees C. on the autumn exercise. Slightly lower values were observed in winter, but this was associated with slower walking rather than cold stress. A fat and a thin subject walking together with minimal clothing showed widely different temperature responses, the fatter subject having a lower skin temperature and higher gut temperature than his companion. These results were compared with other results on extreme cold stress and discussed in relation to hypothermia. Heart rate and blood pressure findings were unremarkable, except for increased post-exercise heart rates and standing/lying heart rate differences, and a tendency to postural hypotension associated with exhaustion. Blood volume was not reduced in exhaustion and there were no significant changes in blood electrolytes or other constituents apart from a small rise in potassium. Ketonuria developed in all subjects.

Adaptation, Physiological↗
PubMed1969

Blood volume changes in outdoor exercise of 8-10 hour duration.

1. Blood volume was measured with carbon monoxide on six hill-walkers before and immediately after a 28-mile walk on two occasions. The subjects had free access to food and fluid.2. Blood volume increased and haematocrit fell significantly on both occasions compared with the control observations. The mean increase of blood volume was 204 ml. or 3.9% (P < 0.01) and the mean reduction of haematocrit was 2.1% (P < 0.02). Plasma volume calculated from these results increased by 233 ml. or 7.3%. There was no significant change in red cell volume or plasma protein concentration.3. These changes are the opposite of those taking place in short-term exercise and suggest that in the absence of dehydration a compensatory adjustment of blood volume takes place during exercise of many hours duration.

Adolescent↗