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Biomedical subjects

R C Goode

Publications and source records attributed to R C Goode.

At least 19 recordsLinked to original sources
PubMed1996

The effect of a rise in body temperature on the central-chemoreflex ventilatory response to carbon dioxide.

We assessed the central-chemoreflex ventilatory responses to carbon dioxide in six male volunteers using a hyperoxic rebreathing technique. Hyperventilation prior to rebreathing allowed both the threshold and the sensitivity of the response to be measured. We used immersion in water to control the body temperature (tympanic). The water temperature was adjusted to be either thermo-neutral or hot so that body temperature either remained normal [+0.2 (0.04) degrees C, mean (SEM)] or was elevated by 1.5 (0.08) degrees C. The sensitivities of the central-chemoreflex ventilatory responses to carbon dioxide were increased at elevated body temperatures, changing from a mean of 1.8 (0.2) 1.min-1. Torr-1 to 2.7 (0.1) 1.min-1. Torr-1. However, the thresholds did not change with temperature, and the mean threshold was 48(1) Torr at both normal and elevated temperatures. For all of the volunteers, ventilation was increased at elevated body temperatures for all levels of carbon dioxide, mainly by changes in respiratory frequency due to reductions in expiratory times. At subthreshold levels of carbon dioxide, mean ventilation changed significantly from 6.3(1.1) 1.min-1 at normal temperatures to 10.8 (1.9) 1.min-1 at elevated temperatures. Heart rates also increased significantly with temperature, changing from a mean of 66 (4) beats.min-1 to 102 (3) beats.min-1 at threshold levels of carbon dioxide. The mean rates of rise of carbon dioxide partial pressure during rebreathing were significantly increased with temperature as well, changing from 0.075 (0.008) Torr.min-1 to 0.089 (0.004) Torr.min-1. We concluded that elevating the body temperatures of our subjects not only increased their ventilation, heart rates and metabolic rates at all levels of carbon dioxide, but it also increased the sensitivity of their central chemoreflex ventilatory responses to carbon dioxide. Despite these increases, the thresholds of the central-chemoreflex ventilatory responses to carbon dioxide remained unchanged.

Adult↗
PubMed1991

Handgrip dynamometry, Cybex measurements and lean mass as markers of the ageing of muscle function.

Isometric handgrip force, isokinetic knee flexion and extension torque, and anthropometric data were obtained on 67 older men and women (ranging in age from 45 to 75 years, mean 59.7 years). Hydrostatic and skinfold estimates of lean body mass were quite closely correlated with each other in this sample (r = 0.93). Handgrip force, isokinetic knee flexion and extension torque, and lean mass all decreased by 6-8% per decade over the age span examined, although in the men the loss was most marked in terms of handgrip and lean mass, whereas in the women the loss of torque in the knee muscles was dominant. Because of these differences, the handgrip data were only weakly correlated with the isokinetic strength measurements (r = 0.22), and the isokinetic data were more strongly related to lean body mass and body mass. The optimum equation for a field prediction of isokinetic strength in this age group (a combination of age, sex, age-sex interaction and lean body mass) has an error approaching 25%, with a multiple r2 of 0.37, and a standard error of the estimate (s.e.e.) of 24.5%. It is concluded that handgrip data and slow isokinetic torque measurements evaluate relatively independent aspects of the ageing of muscular function.

Aged↗
PubMed1990

Postoperative exercise training develops normal levels of physical activity in a group of children following cardiac surgery.

Children with congenital heart defects often demonstrate a reduced capacity for exercise, even after surgical intervention. Forty subjects, with various heart defects, completed a 5-year study to evaluate the impact of a postoperative training program on their physical exercise capacity. All of the patients were significantly less active than their peers prior to the surgical intervention. Subjects who completed a simple, home exercise program during the first 3 postoperative months achieved a normal level of physical fitness. These benefits were maintained up to 5-years postoperatively without further intervention. Children who did not receive a postoperative training program remained significantly below their healthy peers. Therefore, a simple exercise training program, conducted early in the postoperative period would appear essential to the achievement of appropriate levels of physical activity for children with congenital heart defects.

Adolescent↗
PubMed1987

Sleep deprivation and cardiorespiratory function. Influence of intermittent submaximal exercise.

The effects of 64 h of sleep deprivation upon cardiorespiratory function was studied in 11 young men (VO2max = 55.5 ml kg-1 min-1, STPD). Six subjects engaged in normal sedentary activities, while the others walked on a treadmill at 28% VO2max for one hour in every three; eight weeks later, sleep deprivation was repeated with a crossover of subjects. Immediate post-deprivation measurement of VO2max showed a small but statistically significant decrease (-3.8 ml min-1 kg-1, STPD), with no difference between exercise and control trials. The final decrement in aerobic power was not due to a loss of motivation, as 88% (21 of 24) of post-deprivation tests still showed a plateau of VO2max; in addition, terminal heart rates (198 vs 195 beats min-1), respiratory exchange ratios (1.14 vs 1.15) and blood lactate levels (12.1 vs 11.8 mmol l-1) were not significantly different after sleep deprivation. The decrease in VO2max was associated with a lower VEmax (127 vs 142 l min-1, BTPS) and a substantial haemodilution (13%). Physiological responses to sub-maximal exercise showed persistence of the normal diurnal rhythm in heart rate and oxygen consumption, with no added effects due to sleep deprivation. However, ratings of perceived exertion (Borg scale) increased significantly throughout sleep deprivation. The findings are consistent with a mild respiratory acidosis, secondary to reduced cortical arousal and/or a progressive depletion of tissue glycogen stores which are not altered appreciably by moderate physical activity.

Adult↗
PubMed1986

Growth hormone regulation in two types of aerobic exercise of equal oxygen uptake.

Five normal men, aged 23 to 35 years, participated in two bouts of continuous aerobic cycling separated by five days. The first type of exercise (EI) was cycling at a pedalling frequency of 50 rev X min-1 with a load which produced a steady state O2 uptake of approximately 40% of the subjects' VO2max. The second type of exercise (EII) was cycling at a pedalling frequency of 90 rev X min-1 with a load such that an equal steady state VO2 was reached and maintained. Both EI and EII lasted 40 min. GH levels increased in EI and EII, reaching their maximum at 8 min of recovery (245 and 300% of resting values, respectively). No significant differences were observed between EI and EII in GH, lactate, glucagon, insulin, cortisol and glucose levels between the two exercises. While it has been reported earlier that GH levels were frequently related to lactate levels and/or decreased O2 availability (Sutton 1977; Raynaud et al. 1981; Kozlowski et al. 1983; VanHelder et al. 1984a, b), this study suggests that the opposite is also valid, that is, different types of exercise of equal VO2, duration and lactate production do not produce significantly different GH responses.

Adult↗
PubMed1986

Bath rewarming from immersion hypothermia.

Trunk-only bath rewarming has often been recommended over whole-body bath rewarming as a method for the treatment of immersion hypothermia. At present, no report of a direct comparison of the relative merits of these techniques has been made. Authorities in favor of trunk-only bath rewarming base their proposal on the assumption that core temperature afterdrop would be minimized by preventing peripheral vasodilation when the subject's limbs are not immersed in the rewarming bath. In the present study, trunk-only and whole-body bath rewarming are compared by rewarming eight mildly hypothermic male subjects twice, once via each technique. It was concluded that trunk-only rewarming is not superior to whole-body bath rewarming as a therapy for mild immersion hypothermia, based on the findings that no significant differences existed between the two techniques, either in size or duration of core temperature afterdrop, or in rate of rewarming.

Adult↗
PubMed1985

Hormonal and metabolic response to three types of exercise of equal duration and external work output.

Five normal men, aged 20-30 years, participated in three types of exercise (I, II, III) of equal duration (20 min) and total external work output (120-180 kJ) separated by ten days of rest. Exercises consisted of seven sets of squats with barbells on the shoulders (I; Maximal Power Output Wmax = 600-900 W), continuous cycling at 50 rev X min-1 (II; Wmax = 100-150 W) and seven bouts of intermittent cycling at 70 rev X min-1 (III; Wmax = 300-450 W). Plasma cortisol, glucagon and lactate increased significantly (P less than 0.05) during the exercise and recovery periods of the anaerobic, intermittent exercise (I and III) but not in the continuous, aerobic exercise (II). No consistent significant changes were found in plasma glucose. Plasma insulin levels decreased only during exercise II. The highest increase in cortisol and glucagon was not associated with the highest VE, VO2, Wmax or HR; however it was associated with the anaerobic component of exercise (lactic acid). It is suggested that in exercises of equal duration and total external work output, the continuous, aerobic exercise (II) led to lowest levels of glucogenic hormones.

Adult↗
PubMed1984

Growth hormone responses during intermittent weight lifting exercise in men.

Five normal male volunteers performed two intermittent weight lifting exercises of equal total external work output and duration (20 min) with identical work-rest intervals but different load and frequency of movements. Exercise I consisted of seven sets of seven vertical leg lifts at 85% of the subject's Seven Repetition Maximum (SRM) and, 5 days later, seven sets of 21 vertical leg lifts with one-third of the previously used load (Exercise II). Blood was sampled throughout the exercise and recovery periods for growth hormone, lactate, and glucose analysis. Growth hormone increased after 20 min of Exercise I to a peak during the recovery period. Significantly elevated growth hormone (GH) levels were found 5, 10, and 15 min (P less than 0.025, P less than 0.05, P less than 0.025 respectively) of recovery after Exercise I. No significant elevations of GH occurred in Exercise II. Significant linear correlations (r = 0.99, P less than 0.01) with a time lag of 16 min were found between lactate and GH levels in Exercise I (lactate increases preceded those of GH). No significant differences in plasma glucose concentrations were detected. The results suggests that in intermittent weight lifting exercises of equal total external work output and duration as well as identical work-rest intervals, the load and/or frequency of an exercise are determinant factors in the regulation of plasma GH levels.

Adult↗
PubMed1984

Effect of anaerobic and aerobic exercise of equal duration and work expenditure on plasma growth hormone levels.

Growth hormone (GH) and lactic acid levels were measured in five normal males before, during and after two different types of exercise of nearly equal total duration and work expenditure. Exercise I (aerobic) consisted of continuous cycling at 100 W for 20 min. Exercise II (anaerobic) was intermittent cycling for one minute at 285 W followed by two minutes of rest, this cycle being repeated seven times. Significant differences (P less than 0.01) were observed in lactic acid levels at the end of exercise protocols (20 min) between the aerobic (I) and anaerobic (II) exercises (1.96 +/- 0.33 mM X 1(-1) vs 9.22 +/- 0.41 mM X 1(-1), respectively). GH levels were higher in anaerobic exercise (II) than in aerobic (I) at the end of the exercise (20 min) (2.65 +/- 0.95 micrograms X 1(-1) vs 0.8 +/- 0.4 micrograms X 1(-1); P less than 0.10) and into the recovery period (30 min) (7.25 +/- 6.20 micrograms X 1(-1) vs 2.5 +/- 2.9 micrograms X 1(-1); P less than 0.05, respectively).

Adult↗
PubMed1984

Body cooling in human males by cold-water immersion after vigorous exercise.

Five male subjects were immersed to neck level in a whole-body water calorimeter (water temperature 19 degrees C) on two occasions. One immersion was preceded by 30 min of exercise on a treadmill at 80% of the subjects' maximum heart rate, while the other was preceded by no exercise (control). Ventilation, oxygen consumption, hand-grip strength, and heat loss (measured by calorimetry) results showed no significant differences between resting and exercise trials. Minute ventilation and oxygen consumption increased during the immersion but the magnitude of the increase varied among subjects. There was a significant decrease is isometric hand-grip strength after 30 min of immersion. Rectal temperatures fell faster (0.031 degree C +/- 0.004 degree C/min) for exercised subjects than for controls (0.019 degree C +/- 0.005 degree C/min) between 10 and 45 min of immersion (P less than 0.01). It appears that vigorous preimmersion exercise may shorten survival time in cold water due to an increase in cooling rate.

Adult↗
PubMed1980

The ventilatory response to carbon dioxide in hyperoxic exercise.

The sensitivity of the ventilatory response to carbon dioxide in hyperoxia during light (25 W) exercise was compared to that at rest in 14 volunteers. The method used was that of rebreathing. Two factors were found to produce artefactual changes in the slope of the response during exercise. First, breath-by-breath response lines showed that the maximum limit of ventilation was reached in 3 volunteers before the end of rebreathing, despite the low exercise load. The inclusion of such breaths in the calculation of the slope of the response could produce an artefactual decrease in slope. Second, most of the response lines showed an increase in their slope during exercise. However, a model of rebreathing in exercise showed that an increase in sensitivity could be the result of variation in the difference between end-tidal and central chemoreceptor carbon dioxide levels during exercise. A criterion derived from the model, proportional to the variation in this difference, was found to be correlated with the increase in sensitivity from rest to exercise. It was therefore concluded that the sensitivity of the ventilatory response to carbon dioxide during light exercise is unchanged from that at rest.

Adult↗