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Biomedical subjects

C Williams

Publications and source records attributed to C Williams.

At least 487 records · Page 27Linked to original sources
PubMed1989

Aerobic fitness and running performance of male and female recreational runners.

The purpose of the present study was to assess fitness and running performance in a group of recreational runners (men, n = 18; women, n = 13). 'Fitness' was determined on the basis of their physiological and metabolic responses during maximal and submaximal exercise. There were strong correlations between VO2 max and treadmill running speeds equivalent to blood lactate concentrations of 2 mmol l-1 (V-2 mM) or 4 mmol l-1 (V-4 mM), 'relative running economy' and 5 km times (r = -0.84), but modest and non-significant correlations between muscle fibre composition and running performance. The results of the submaximal exercise tests suggested that the female runners were as well trained as the male runners. However, the men still recorded faster 5 km times (19.20 +/- 1.97 min vs 20.97 +/- 1.70 min; P less than 0.05). Therefore the of the present study suggest that the faster performance times recorded by the men were best explained by their higher VO2 max values, rather than their training status per se.

Adult↗
PubMed1989

Increased dietary carbohydrate and endurance during single-leg cycling using a limb with normal muscle glycogen concentration.

The purpose of this study was to test the hypothesis that increased availability of blood-borne glucose would improve endurance after carbohydrate loading. A single-leg exercise model was employed, taking advantage of the fact that supercompensation of muscle glycogen occurs only in a previously exercised limb. Endurance time to exhaustion at 70% of maximal oxygen uptake (VO2 max) was determined for 11 males and three females who were then allocated to a control group or a high-carbohydrate (CHO) group. For 3 days following Test 1 the control group maintained a prescribed normal diet whilst the CHO group increased the proportion of energy derived from carbohydrate (62.1 +/- 4.3% cf. 43.9 +/- 2.0%, P less than 0.01). The endurance test was then repeated using the leg that was inactive during Test 1. Endurance time was increased on Test 2 (123.7 +/- 43.2 min cf. 98.5 +/- 21.9 min, P less than 0.05 one-tailed test) for the CHO group but not for the control group (101.8 +/- 21.7 min cf. 107.5 +/- 9.1 min, NS). There was no indication of enhanced carbohydrate metabolism during Test 2 for the CHO group but mean heart rate was lower during Test 2 than during Test 1 (145 +/- 14 beat min-1 cf. 152 +/- 12 beat min-1, P less than 0.05). These results suggest that the prior consumption of a high-carbohydrate diet improves endurance during high-intensity cycling with a limb with normal muscle glycogen concentration.

Adult↗
PubMed1989

The effect of endurance running training on asthmatic adults.

Nine mild to moderate asthmatic adults (three males, six females) and six non-asthmatics (one male, five females) underwent endurance running training three times per week for five weeks, at self selected running speeds on a motorized treadmill. After training, the asthmatic group had a significantly higher maximum oxygen uptake, significantly lower blood lactate and heart rate in submaximal running, and significantly reduced time to complete a two mile treadmill run, partly attributable to the ability to exercise at a higher % VO2 max after training. These training induced changes of the asthmatic group were generally of a greater magnitude than those shown by the non-asthmatic group. Although seven of the nine asthmatics did show a reduction in the post-exercise fall in FEV1 after the five week training period, this was not statistically significant for the asthmatic group as a whole. The results of this study therefore suggest that endurance running training can improve the aerobic fitness of asthmatic adults, and may reduce the severity of exercise-induced asthma.

Adolescent↗
PubMed1989

Training induced physiological and metabolic changes associated with improvements in running performance.

The purpose of the present study was to examine the relationship between improvements in running performance and some of the prominent physiological and metabolic adaptations to endurance exercise training. Twelve male undergraduates agreed to participate in this study (trial group), aged matched physical education students provided a control group. Running performance, assessed as a five km time trial, improved from 19.69 +/- 2.24 to 19.22 +/- 2.03 min in the trial group (P less than 0.01) after training. Maximal oxygen uptake values increased from 56.0 +/- 6.1 to 60.7 +/- 5.4 ml.kg-1.min-1, the running speed equivalent to a blood lactate reference concentration of 4 mmol.l-1 (V-4 mM) increased from 3.79 +/- 0.77 to 4.04 +/- 0.71 m.s-1, and the rate of oxygen consumption at 3.58 m.s-1 (running economy) increased from 43.3 +/- 3.2 to 45.0 +/- 3.4 ml.kg-1.min-1 (P less than 0.01). The control group did not show any significant changes. The improved five km times in the trial group were significantly correlated (r = -0.71; P less than 0.01) with changes in the running economy rather than changes in the VO2 max (r = -0.07; ns), or V-4 mM (r = -0.13; ns) suggesting the increased rate of oxygen utilization reflected a greater oxidative degradation of metabolic substrates together with a slower rate of lactate production.

Humans↗
PubMed1989

Effect of training on muscle metabolism during treadmill sprinting.

Sixteen subjects volunteered for the study and were divided into a control (4 males and 4 females) and experimental group (4 males and 4 females, who undertook 8 wk of sprint training). All subjects completed a maximal 30-s sprint on a nonmotorized treadmill and a 2-min run on a motorized treadmill at a speed designed to elicit 110% of maximum oxygen uptake (110% run) before and after the period of training. Muscle biopsies were taken from vastus lateralis at rest and immediately after exercise. The metabolic responses to the 110% run were unchanged over the 8-wk period. However, sprint training resulted in a 12% (P less than 0.05) and 6% (NS) improvement in peak and mean power output, respectively, during the 30-s sprint test. This improvement in sprint performance was accompanied by an increase in the postexercise muscle lactate (86.0 +/- 26.4 vs. 103.6 +/- 24.6 mmol/kg dry wt, P less than 0.05) and plasma norepinephrine concentrations (10.4 +/- 5.4 vs. 12.1 +/- 5.3 nmol/l, P less than 0.05) and by a decrease in the postexercise blood pH (7.17 +/- 0.11 vs. 7.09 +/- 0.11, P less than 0.05). There was, however, no change in skeletal muscle buffering capacity as measured by the homogenate technique (67.6 +/- 6.5 vs. 71.2 +/- 4.5 Slykes, NS).

Adult↗
PubMed1989

Heterotopic neurons in spinal cord of patients with ALS.

Monoclonal antibody 44.1, an immunocytochemical marker for neurons, identified heterotopically located, multipolar neurons deep within the spinal cord white matter of patients with amyotrophic lateral sclerosis. Displaced neurons were most numerous in the ventral outflow and lateral corticospinal tract regions of all cord levels. These changes may be the result of aberrant neuronal migration during spinal cord development.

Adult↗
PubMed1989

Psychological impact of the diagnosis of gestational diabetes.

The psychological impact of the diagnosis of gestational diabetes was examined in 68 pregnant women. No differences between the women with gestational diabetes and 50 non-diabetic pregnant controls, matched for gestational age, were found on the Profile of Mood States--Bipolar Form. Contrary to clinical lore, the prescription of insulin was not found to have an adverse effect on the emotional status of women with gestational diabetes. In this diabetic population whose blood glucose levels were well controlled, psychological status was not found to be related to blood glucose levels. The results suggest that the majority of pregnant women adapt readily to the unexpected diagnosis of gestational diabetes.

Adult↗
PubMed1989

Changes in intraventricular septal thickness, left ventrical wall thickness and left ventricular volume in obese adolescents on a high protein weight reducing diet.

Ten obese adolescents (153 percent ideal body weight) underwent significant weight reduction over a two to three month period using a low calorie, low carbohydrate, protein diet. The subjects lost a mean of 13.9 +/- 4.3 kg, representing a decrease of 15.5 +/- 5.0 percent of initial body weight. Serial measures of intraventricular septal thickness (ST), left ventricular wall thickness (LVWT) and left ventricular volume (LVV) were determined by standard m-mode echocardiographic methods over 14 weeks to determine the effect of weight reduction on these indicators of cardiac size. The ST changed over the study period from 8.2 +/- 1.9 mm to 7.3 +/- 2.0 mm; the LVWT from 7.6 +/- 1.8 mm to 6.3 +/- 1.1 mm; and the LVV from 47.1 +/- 4.0 mm to 42.0 +/- 2.8 mm. These numerical decreases were not significantly different. Over this study period, the diet allowed weight loss with no apparent effect on the cardiac size (ST, LVWT, LVV) as measured by echocardiography in these obese adolescents.

Adolescent↗
PubMed1988

Trying times.

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Adaptation, Psychological↗
PubMed1988

Sequence analysis of the junction of the large single copy region and the large inverted repeat in the petunia chloroplast genome.

We have determined the nucleotide sequence at the junction of the large single copy (LSC) region and the right and left members of the large inverted repeat, IRA and IRB, respectively, of the petunia chloroplast (cp) genome. As in Nicotiana debneyi and spinach (Zurawski et al. 1984), coding sequences of rps19 of petunia overlap the junction of IRB and LSC. Immediately into the LSC region upstream of IRA in the petunia cp genome are two small insertions relative to N. debneyi that occur at sites just inside IRA of N. debneyi. We discuss how these additions in one copy of the large inverted repeat of an N. debneyi-like ancestor to petunia resulted in shortening of the petunia large inverted repeat by 8 bases and in the resultant slight movement of rps19 farther into LSC. On a larger scale, the large inverted repeat in the tobacco, N. debneyi and petunia lineage relative to a spinach-like ancestor may have sustained several contractions due to deletions between short direct repeats found within IRA and the IRA/LSC junction. We also show how the large inverted repeat of N. debneyi instead may have been expanded relative to a tobacco-like ancestor by insertion into the large inverted repeat of bases between short inverted repeat sequences in LSC and the LSC/IRB junction.

Base Sequence↗
PubMed1988

The responses of the catecholamines and beta-endorphin to brief maximal exercise in man.

The responses to brief maximal exercise of 10 male subjects have been studied. During 30 s of exercise on a non-motorized treadmill, the mean power output (mean +/- SD) was 424.8 +/- 41.9 W, peak power 653.3 +/- 103.0 W and the distance covered was 167.3 +/- 9.7 m. In response to the exercise blood lactate concentrations increased from 0.60 +/- 0.26 to 13.46 +/- 1.71 mmol.l-1 (p less than 0.001) and blood glucose concentrations from 4.25 +/- 0.45 to 5.59 +/- 0.67 mmol.l-1 (p less than 0.001). The severe nature of the exercise is indicated by the fall in blood pH from 7.38 +/- 0.02 to 7.16 +/- 0.07 (p less than 0.001) and the estimated decrease in plasma volume of 11.5 +/- 3.4% (p less than 0.001). The plasma catecholamine concentrations increased from 2.2 +/- 0.6 to 13.4 +/- 6.4 nmol.l-1 (p less than 0.001) and 0.2 +/- 0.2 to 1.4 +/- 0.6 nmol.l-1 (p less than 0.001) for noradrenaline (NA) and adrenaline (AD) respectively. The plasma concentration of the opioid beta-endorphin increased in response to the exercise from less than 5.0 to 10.2 +/- 3.9 p mol.l-1. The post-exercise AD concentrations correlated with those for lactate as well as with changes in pH and the decrease in plasma volume. Post-exercise beta-endorphin levels correlated with the peak speed attained during the sprint and the subjects peak power to weight ratio. These results suggest that the increases in plasma adrenaline are related to those factors that reflect the stress of the exercise and the contribution of anaerobic metabolism.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

The influence of high carbohydrate diets on endurance running performance.

The purpose of the present study was to examine the influence of high carbohydrate (CHO) diets on recovery of endurance capacity following a treadmill run to exhaustion. Two high CHO diets were used, one in which the normal diet was supplemented with complex carbohydrates and the other in which supplementation was achieved with simple carbohydrates. The thirty recreational runners who took part in this study (fifteen men and fifteen women) completed weighed food intake diaries two to three weeks before the start of the study. From an analysis of this information each subject's 'normal diet' was prescribed before Trial 1 and then a supplemented diet before Trial 2. The aim was to achieve an increase in carbohydrate content to 70% in the diets of the two high CHO groups and an equivalent increase in energy intake by the Control group. The subjects were required to run to exhaustion on a treadmill at a speed equivalent to 70% VO2max on two occasions separated by 3 days. After Trial 1 the subjects were divided into three equal groups. The Complex CHO group (301 +/- 86 mg vs 507 +/- 120 mg) and Simple CHO group (265 +/- 45 mg vs 462 +/- 81 mg) increased their CHO intake by approximately 70% (p less than 0.05) during the 3 days before Trial 2 whereas the Control group increased their energy intake with additional protein and fat so as to match the energy intakes of the two CHO groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Body Weight↗