Robert Goode

Growth hormone responses during intermittent weight lifting exercise in men

SummaryFive 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 subjects 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<0.025,P<0.05,P<0.025 respectively) of recovery after Exercise I. No significant elevations of GH occurred in Exercise II. Significant linear correlations (r=0.99,P<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.

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

SummaryGrowth 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<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·l−1 vs 9.22±0.41 mM·l−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 Μg·l−1 vs 0.8±0.4 Μg·l−1;P<0.10) and into the recovery period (30 min) (7.25±6.20 Μg·l−1 vs 2.5±2.9 Μg·l−1;P<0.05, respectively).

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

SummaryChildren 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.

The effect of duration of exercise at the ventilation threshold on subjective appetite and short-term food intake in 9 to 14 year old boys and girls

BackgroundThe effect of exercise on subjective appetite and short-term food intake has received little investigation in children. Despite a lack of reported evaluation of short-duration activity programs, they are currently being implemented in schools as a means to benefit energy balance. The purpose of this study was to determine the effect of duration of exercise at the ventilation threshold (VeT) on subjective appetite and short-term food intake in normal weight boys and girls aged 9 to 14 years.MethodsOn 4 separate mornings and in random order, boys (n = 14) and girls (n = 15) completed 2 rest or 2 exercise treatments for 15 (short-duration; SD) or 45 min (long-duration; LD) at their previously measured VeT, 2 h after a standardized breakfast. Subjective appetite was measured at regular intervals during the study sessions and food intake from a pizza meal was measured 30 min after rest or exercise.ResultsAn increase in average appetite, desire to eat, and hunger (p < 0.05) was attenuated by SD exercise, but was further increased (p < 0.05) by LD exercise. However, food intake after SD and LD exercise was similar to after rest in both boys and girls (p = 0.55). The energy cost of SD and LD exercise resulted in a lower net energy balance compared to resting during the study measurement period in boys (SD: Δ = -418 ± 301 kJ; LD: Δ = -928 ± 196 kJ) and in girls (SD: Δ = -297 ± 105 kJ; LD: Δ = -432 ± 115 kJ).ConclusionNeither SD nor LD exercise at the VeT increased short-term food intake and SD exercise attenuated increases in appetite. Thus, SD exercise programs in schools may be an effective strategy for maintaining healthier body weights in children.

Effect of short-duration physical activity and ventilation threshold on subjective appetite and short-term energy intake in boys

The purpose of this investigation was twofold: (1) to examine the role of low- to moderate-intensity, short-duration physical activity on subjective appetite and (2) to identify the role of and associations between ventilation threshold (VeT) and energy intake at a pizza lunch 30 min after glucose and whey protein drinks in normal weight boys. In 14 boys (age: 12.5+/-0.4 years) subjective appetite was measured before and after a 12 min walking protocol designed to determine physical fitness based on the VeT. On a separate occasion food intake (FI) and subjective appetite were measured in response to sweetened preloads of either a SPLENDA Sucralose control, glucose or whey protein made up to 250 ml with water, given in random order to each boy, 2h after a standardized breakfast. Subjective average appetite and prospective food consumption scores increased after physical activity. VeT was positively associated with FI at a pizza lunch consumed 30 min after glucose and whey protein drinks. Glucose and whey protein reduced FI similarly at lunch compared with control. In conclusion, appetite is increased by low- to moderate-intensity, short-duration physical activity and FI following glucose and protein preloads is positively associated with fitness levels in boys.

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

SummaryFive 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

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

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The ventilatory response to carbon dioxide in hyperoxic exercise

max=600−900 W), continuous cycling at 50 rev · min−1 (II;