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1.  Serum lipids: interactions between age and moderate intensity exercise. 
The purpose of this study was to examine relationships between age and selected serum lipids and lipoproteins in women before and after a physical fitness programme. Twenty females 27-59 years of age who had participated in the Purdue University Physical Fitness Programme were selected and placed into one of two groups: "junior" (mean age 34, all under 40 yrs) or "senior" (mean age 50, all over 43). A two way factorial design was used to study differences in serum triglycerides (TG), total cholesterol (TC), low density lipoprotein cholesterol (LDLC), high density lipoprotein cholesterol (HDLC), and the risk ratios TC/HDLC and LDLC/HDLC associated with physical fitness and the eight month physical fitness programme. The ability of the biochemical variables to discriminate between the age groups was investigated using discriminant function analyses. The analyses of variance indicated that although the two age groups were matched on the basis of a multivariate physical fitness score (Ismail et al, 1965) the older group was heavier (p less than 0.05), and had higher systolic and pulse pressures (p less than 0.05). Both groups increased their physical fitness score from pre to post programme (p less than 0.01). No significant age related biochemical differences were noted in the univariate analyses; however, in the discriminant function analyses the biochemical variables significantly discriminated between the two groups before, but not after the programme. A decrease in serum triglycerides was observed in the more highly fit women in each age group. These findings suggest that moderate levels of physical activity may help to counteract some of the undesirable changes in the lipid profile associated with age.
PMCID: PMC1478530  PMID: 4027494
2.  Serum insulin and glucose response to graded exercise in adults. Part II. The effect of exercise conditioning. 
The effect of conditioning to severe exercise upon serum immunoreactive insulin levels (IRI) and serum glucose concentrations (GC) was studied in active and sedentary groups of middle-aged men. The responses of serum IRI and serum GC were determined during graded cycle ergometer exercise which required similar low and high relative work intensities, before (pre) and after (post) a four month physical fitness programme. Both groups demonstrated a marked decline in serum IRI during high intensity exercise from pre to post tests, and a tendency to maintain serum, GC (sedentary group) or elevate serum GC (active group) during exercise, following the conditioning programme. The data provides evidence of a bi-directional response of serum IRI and serum GC to graded exercise, with only minor modifications in the response patterns resulting from exercise conditioning.
PMCID: PMC1859654  PMID: 719323
3.  Serum insulin and glucose response to graded exercise in adults. Part I: the influence of fitness status. 
The effect of acute exercise upon serum immunoreactive insulin levels (IRI) and serum glucose concentrations (GC) was studied in groups of middle-aged men of contrasting physical fitness status. Two groups of subjects, one active and one sedentary (both N = 11, mean age 44 years), performed a graded cycle ergometer exercise test in the post-absorptive state. Venous blood samples were taken at rest, during low and high work intensities, and after recovery. The response of serum IRI to exercise was similar in both groups of subjects with significant increases observed during exercise followed by a return to resting values during recovery. However, the magnitude of serum IRI response was lower in the active group. In contrast, the sedentary group demonstrated little or no change in serum GC during exercise, whereas significant increases in serum GC were observed during exercise in the active group.
PMCID: PMC1859642  PMID: 687888
4.  Effects of exercise on free serum cholesterol. 
Two age groups (young and old, n = 12) matched for physical fitness and two physical fitness groups (high and old, n = 12) matched for age participated in a four month physical fitness programme. Blood samples were drawn at four stages of metabolic stress at the pre-test and five stages at the post-test. The blood samples were analyzed by colorimetric methods for total cholesterol and free cholesterol. Statistical analysis revealed that: (1) Short-term exercise increased total cholesterol, free cholesterol, and the percent free cholesterol from the resting state to the submaximal and maximal exercise states. (2) There was no change in free serum cholesterol from the pre- to post-tests. (3) The high-fit group, compared with the low-fit group, had a lower free cholesterol level but had similar percent free cholesterol values. (4) There was no significant difference between age groups for either total serum cholesterol, free cholesterol, or the percent free cholesterol levels.
PMCID: PMC1859549  PMID: 861438
5.  Effect of prolonged exercise of serum testosterone levels in adult men. 
The purpose of the study was to: 1) identify the differences in serum testosterone levels among four groups of adult men differentiated on the basis of physical fitness and age, and 2) determine the effect of a four-month physical fitness programme consisting of running, calisthenics and recreational activities on the serum testosterone levels of the four groups. The groups were designated: high-fit, young aged about 32 (n = 7); high-fit, old aged about 52 (n = 7); low-fit, young (n = 7), and low-fit, old (n = 7). The subjects were selected and grouped according to physical fitness scores obtained using the regression equation of Ismail et al. Serum testosterone was determined by a radioimmunoassay method. The pre-test ANOVA revealed that the high-fit groups had a significantly (p less than .01) higher testosterone level (754.29 ng/100 ml) than the low-fit groups (548.07 ng/100 ml) and the high-fit, young group (925.01 ng/100 ml) was significantly (p less than .01) higher than the other three groups. Post-test values were adjusted using pre-test testosterone values as covariates. No significant differences among the groups were found indicating that the serum testosterone levels were the same regardless of different ages and fitness levels. The findings were discussed in light of physiological, biochemical and psychological factors.
PMCID: PMC1859523  PMID: 1009301
6.  Variability of corticosteroid responses during exercise stress in active and sedentary middle-aged males. 
Two groups of middle-aged male subjects (both N=11), one active (mean age 44.6 years) and one sedentary (mean age 43.7 years), undertook a graded exercise stress test on a bicycle ergometer in the post-absorptive state. Blood serum corticosteroid levels were measured at the following stages of metabolism; at rest, under conditions of submaximal and "maximal' exercise and during recovery. The active group showed no significant change in mean serum corticosteroid levels from resting values, during exercise and recovery. However the sedentary group displayed a significant increase in mean serum corticosteroid levels from a resting value of 5.81 plus or minus 0.41 mub-g/100 ml. (mean plus or minus S.E.) to 7.83 plus or minus 0.71 mug/100 ml. during "maximal' exercise (p smaller than 0.05), which was maintained throughout recovery 7.82 plus or minus 0.70 ug/100 ml (p smaller than 0.05). Futhermore the active group demonstrated significantly lower mean serum corticosteroid levels compared with the sedentary group under conditions of submaximal (p smaller than 0.05) and "maximal' (p smaller than 0.01) exercise and during recovery (p smaller than 0.01). It was concluded that the variability in the response patterns of serum corticosteroids during exercise stress in active and sedentary middle-aged males, reflected the physiological differences observed between the two groups of subjects.
PMCID: PMC1859307  PMID: 1148579

Results 1-6 (6)