High-active Subjects Research Articles

Influence Of Physical Activity On Muscle And Fat Depots Assessed By pQCT

The location and mass of adipose tissue affects disease risk, especially when located centrally. Although physical activity (PA) can attenuate fat accumulation over the total body and trunk, effects on fat depots in the limbs is limited. Analysis of the soft tissues of the limbs, including adipose depots, is possible with magnetic resonance imaging (MRI) and peripheral quantitative computed tomography (pQCT). Specifically, intermuscular adipose tissue (IMAT), the adipose tissue within the fascia surrounding muscle, has been explored (Miljkovic-Gacic et al. Am J Clin Nut 2008). MRI analysis has shown associations between higher concentrations of IMAT and insulin resistance, type II diabetes, and reduced muscular strength. However the relationship of PA with IMAT has not been fully explored. PURPOSE: To evaluate the influence of PA on IMAT, subcutaneous fat, and muscle area of the non-dominant foreleg in comparison with total and central body fat. METHODS: 70 pre-menopausal women (Mean age ± SD 38.4 ± 4.7 yr) underwent dual energy X-ray absorptiometry (DXA) scans to assess total and central fat and pQCT measurements at a point 66 percent from the tibial distal end to quantify muscle and fat cross-sectional areas. Four day self-reported PA and pedometer step count was translated into MET level x time and then averaged. Subjects were divided into PA tertiles; low active (n = 23; 249.4 ± 82.1 MET·min/day; BMI = 28.1 ± 6.1 kg/m2) and high active were compared (n = 23; 786.7 ± 150.5 MET·min/day; BMI = 22.2 ± 2.1 kg/m2). Independent t-tests were performed between scores for highest and lowest PA tertiles; PA, fat, and muscle scores were correlated, after normalization for BMI. RESULTS: Low active subjects had greater BMI*, subcutaneous fat/BMI*, total* and central body fat*. High active subjects had greater muscle area/BMI* and IMAT/BMI*. IMAT was positively correlated with MET·min/day (r = 0.46*) and muscle area/BMI (r = 0.35*), but was negatively correlated with total (r = -0.46*) and central body fat (r = -0.42*). _______ *p<0.05 CONCLUSIONS: When data was adjusted for body size, IMAT is greater in high active subjects as with muscle area and may suggest a physiological adaptation to increased habitual PA. IMAT may be a useful index for evaluating localized training effects on metabolic adaptations in skeletal muscle.

Explosive Force and Fractionated Reaction Time in Elderly Low- and High-Active Women

The purpose of this study was to determine whether muscle power, activation time, and neuromuscular stimulation are related to physical activity patterns in older women. Forty women (65-84 yr) were assigned to high-active (HA) and low-active (LA) groups on the basis of a historical activity questionnaire, and then they performed a series of maximal, voluntary, isometric knee extensions in a visually cued RT task. Fractionated RT measures were taken using three landmarks in the data: the presentation of the visual stimulus, the beginning of the EMG burst, and the initiation of force development. The rate and magnitude of neural stimulation were taken from surface EMG. Peak torque was 15% greater, rate of torque development was 26% greater, motor time was 17% shorter, rate of EMG rise was 25% faster, and onset EMG magnitude was 15% greater in HA than in LA subjects (P<0.05). These results indicate that older women with a history of vigorous activity can generate greater force, power, and motor output in comparison with their less active peers. The lower-body mass index of the HA subjects and 310% greater volume of physical activity are likely to account for the enhanced neuromuscular function seen. It is plausible that in addition to aging, physical inactivity is responsible for a large portion of the loss of neuromuscular function seen in older adults.

Daily physical activity and physical fitness from adolescence to adulthood: A longitudinal study

The stability of physical fitness and physical activity in Flemish males from 18 to 40 years of age was investigated. In addition, effects of a consistently low-activity or high-activity level during the same age period on physical fitness were studied. The sample consisted of males who were followed longitudinally from age 13 to age 18 years, and were remeasured at the ages of 30, 35, and 40 years. Complete data about physical fitness and physical activity between 13 and 40 years were available for 130 subjects. Stability was measured using Pearson autocorrelations and simplex models. Multivariate analysis of variance (MANOVA) for repeated measurements was used to look for the effects of activity level on physical fitness. Simplex models showed higher stability coefficients than Pearson correlations, and stability of physical fitness was higher than stability of physical activity. Physical fitness showed the highest stability in flexibility (r = 0.91 between 18 and 30 years, r = 0.96 for both the 30–35 and 35–40 ages intervals), while physical activity showed the highest stability during work (r between 0.70 and 0.98 for the 5-year intervals). Results from MANOVA indicated that for some fitness characteristics the high-active subjects were more fit than their low-active peers. Stability of physical activity was higher than assumed and, therefore, it is a useful and independent indicator for further research. Although possible confounding factors are present (e.g., heredity), a higher level of physical activity during work and leisure time on a regular basis benefits physical fitness considerably. Am. J. Hum. Biol. 12:487–497, 2000. © 2000 Wiley-Liss, Inc.

Personality correlates of autobiographical memory

The purpose of this study was to examine the relationship between personality traits and autobiographical memory. Ninety-one (91) undergraduates completed an autobiographical memory questionnaire, describing experiences of unpleasant emotional episodes, and then rating their qualities: Vividness, emotionality, influence, and so on. They also completed a number of personality inventories, including the Yatabe-Guilford Personality Inventory and Self-Acceptance Inventory. Results indicated that emotionally stable and high-activity subjects perceived past unpleasant episodes as more positive, although there was no qualitative difference. Compared with emotionally unstable and low-activity subjects, they also had a higher self-acceptance score, and acknowledged and accepted own shortcomings. People with adaptive personality appear to have positive views on many aspects of the self. These findings were interpreted from the self-schema perspective of memory.

Daily physical activity and physical fitness from adolescence to adulthood: A longitudinal study.

The stability of physical fitness and physical activity in Flemish males from 18 to 40 years of age was investigated. In addition, effects of a consistently low-activity or high-activity level during the same age period on physical fitness were studied. The sample consisted of males who were followed longitudinally from age 13 to age 18 years, and were remeasured at the ages of 30, 35, and 40 years. Complete data about physical fitness and physical activity between 13 and 40 years were available for 130 subjects. Stability was measured using Pearson autocorrelations and simplex models. Multivariate analysis of variance (MANOVA) for repeated measurements was used to look for the effects of activity level on physical fitness. Simplex models showed higher stability coefficients than Pearson correlations, and stability of physical fitness was higher than stability of physical activity. Physical fitness showed the highest stability in flexibility (r = 0.91 between 18 and 30 years, r = 0.96 for both the 30-35 and 35-40 ages intervals), while physical activity showed the highest stability during work (r between 0.70 and 0.98 for the 5-year intervals). Results from MANOVA indicated that for some fitness characteristics the high-active subjects were more fit than their low-active peers. Stability of physical activity was higher than assumed and, therefore, it is a useful and independent indicator for further research. Although possible confounding factors are present (e.g., heredity), a higher level of physical activity during work and leisure time on a regular basis benefits physical fitness considerably. Am. J. Hum. Biol. 12:487-497, 2000. Copyright 2000 Wiley-Liss, Inc.

The Reliability and Validity of a 6-Minute Walk Test as a Measure of Physical Endurance in Older Adults

The purpose of this study was to assess the reliability and validity of a 6-min walk test as a measure of physical endurance in older adults. Seventy-seven subjects, ages 60-87. performed three separate 6-min walk tests and a treadmill test and completed questionnaire items assessing physical activity level and functional status. The 6-min walk had good test-retest reliability (.88 &lt;R &lt; .94). particularly when a practice trial preceded the test trial. Convergent validity of the 6-min walk was demonstrated by its moderate correlation (.71 &lt; r &lt; .82) with treadmill performance. Construct validity was assessed by determining the ability of the test to detect differences between different age and activity level groups. As expected, walking scores decreased significantly across decades and were significantly lower for low-active subjects compared to high-active subjects. There was a moderate relationship between 6-min walk scores and self-reported functional ability. It was concluded that the 6-min walk can be used to obtain reasonably reliable and valid measures of physical endurance in older adults and that it moderately reflects overall physical functional performance.

Responses to Physical Exertion in Active and Inactive Males and Females

An experiment is presented that investigates the relationship between gender, exercise history, and psychological affect during and after exercising at different workloads. High-active and low-active subjects reported their psychological affect in the last 30 s of and 5 min after exercising at 60 and 90% VO2max workloads. Results indicated that high-active subjects (both males and females) were significantly more positive in the 90% workload condition than were the low-active group, but there was no difference between the groups in the 60% workload condition (p &lt; .001). These results suggest that psychological affect in exercise settings is influenced by exercise history, workload, and time when self-reported affect is requested.

Responses to preferred intensities of exertion in men differing in activity levels

We compared ratings of perceived exertion (RPE), state anxiety, percentage of peak oxygen uptake (% VO2peak), percentage of ventilatory threshold (% Tvent), and blood lactate concentration [HLa] in 11 high-active and 12 low-active men (23 +/- 3 yr) at self-selected power outputs during 20 min of cycling. The high-active group selected higher power outputs than did the low-active group, but % VO2peak and % Tvent were lower for the high-active subjects during the initial 5-10 min of cycling. Both groups reported increased RPE across time, but contrary to past studies of load-incremented cycling, RPE was identical for the groups despite their differences in relative intensity. No differences were found for [HLa] or state anxiety during cycling. The groups did not differ on exertional symptoms, but the high-active subjects reported a significant reduction in state anxiety immediately after cycling. A preferred exertion protocol provides an alternative approach to identifying influences on perceived exertion during prolonged exercise. The influence of physical activity history/status on the association between the concomitant pattern of self-selected power outputs and postexercise anxiety reduction merits study.

Instrumental conditioning of skin potential responses in curarized cats: non specific effects of a punishment procedure.

This study evaluates the effects of a punishment paradigm upon electrodermal activity (EDA) in curarized cats. In ten experimental subjects, any skin potential response (SPR) exceeding threshold value was punished by an electric shock. Ten control subjects received an electric shock or an electric stimulation of the mesencephalic reticular formation unrelated to the EDA. The results show that: a) No significant modifications of EDA occurred in subjects characterized by low initial activity; b) The frequency of SPR significantly decreased in high activity subjects used both for the experiments and the controls. Therefore, this diminution, in experimental subjects, cannot be due to a learning process. Neither can it be related to level of curarization or to rate of artificial ventilation. It is suggested that this effect results from a non-specific cortical inhibitory mechanism acting on the reticular activating system. The results obtained in three decorticated cats submitted to a punishment procedure are in accordance with such an hypothesis. Consequently the existence of operant autonomic learning remains unproven.

The relationship between physical activity and serum lipids and lipoproteins in black children and adolescents

This study assesses the association between the serum lipid and lipoprotein levels of 62 black children and 37 black adolescents and their reported levels of habitual physical activity, 24-hour dietary intake, and physical measurements. In the children physical activity was not correlated with serum lipid and lipoprotein levels. Indicators of physical activity had a positive correlation (P less than 0.02) with high-density-lipoprotein cholesterol and negative correlations (P less than 0.05) with the total serum cholesterol/high-density-lipoprotein cholesterol and low-density-lipoprotein cholesterol/high-density-lipoprotein cholesterol ratios in the adolescents. Subjects were stratified into "low activity" and "high activity" groups. High-activity subjects had lower (P less than 0.05) total serum cholesterol/high-density-lipoprotein cholesterol and low-density-lipoprotein cholesterol/high-density-lipoprotein cholesterol ratios than less active subjects. Subjects that ran track had lower (P less than 0.02) total serum cholesterol and low-density-lipoprotein cholesterol than non-track participants. The results suggest that increased habitual physical activity may have a favorable effect on serum lipid and lipoprotein levels in black adolescents.

Electrophysiological and behavioral correlates of arousal

The relationships among levels of activity, responsiveness, exploration, and cortical arousal were assessed in a group of similarly reared male rats from a strain that was highly inbred to maximize genetic homogeneity. In Experiment 1, 22 subjects were tested in a complex, compartmentalized open field (i.e., a closed field), and those falling approximately 1 SD above or below the group activity mean (eight were eliminated) were designated as high- or low-active, implanted with electrodes, and tested electrophysiologically to ascertain the level of cortical arousal as determined via measurements of visually evoked potential afterdischarge amplitude. High-active subjects demonstrated a significantly lower afterdischarge amplitude, indicating that behavioral arousal may be indexed by a readily quantifiable electrophysiological measure. A second group of 14 rats (Experiment 2) was tested and retested after 45 days in the closed field, estabhshing that high- or low-behavioral responsiveness is a stable characteristic. Subjects then received 2 days’ exposure to one of two dissimilar compartments of an exploratory apparatus and were tested to determine amount of time spent in the familiar vs. novel compartments. High-active rats were found to demonstrate significantly shorter initial response latencies. However, no other differences were found. These rats were next tested in a completely open field. No significant activity differences were discovered. These findings show that a high level of arousal as a response to a highly complex environment or intense stimulation is not related to generalized activity elicited in a low-complexity environment (e.g., the open field). These findings also indicate that similarly reared rats may be differently influenced by novel, complex, or intense stimuli, such that some subjects become highly responsive and cortically aroused, whereas others respond with low levels of behavioral and cortical activation. The findings are discussed in terms of cortical and subcortical mechanisms mediating arousal.

Effects of Various Stimuli on Activity Level and Learning by High- and Low-Active Retarded Children

Abstract Increased attention has recently been directed toward research on motor activity levels of mentally retarded children. Very high rates, as well as very low rates, are observed more frequently in mentally retarded populations than in nonretarded populations. The effects on activity levels of external stimuli, such as noise and light, have created interest in researchers for some time. Sixty-nine retarded children were classified according to activity rates and presented two learning tasks under four conditions: (a) quiet unstimulated; (b) noise and light stimuli; (c) pretest exercise; (d) pretest exercise, noise and light stimuli. Analysis indicated that the lower the intelligence the higher the activity level. High-active subjects had a decrease in learning performance in condition b and condition d. Low-active subjects remained low-active for all conditions and high-active subjects remained high-active for all conditions. Lower learning performance was observed for high-active subjects over all ...

Social and genotypic aspects of open-field behavior of two lines of mice

Sixty male and sixty female mice selected for high and low open-field activity were tested either alone, with a same-sex, high-activity companion, or with a same-sex, low activity companion. All subjects except low-activity females became less active when tested with either type of companion, although only the difference between high-activity females tested alone or with a companion was significant. Defecation scores of high-activity subjects were unaffected by the presence of either type of companion. In contrast, defecation scores of low-activity subjects were significantly reduced only when tested with a high-activity companion. The results were interpreted in terms of social facilitation.