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Biomedical subjects

S A Plowman

Publications and source records attributed to S A Plowman.

17 recordsLinked to original sources
PubMed1994

Physiologic responses to forward and retrograde simulated stair stepping.

This study compared the physiologic responses to forward and retrograde simulated stair stepping on the StairMaster 4000 PT. Twenty male subjects (mean age 23.65 +/- 1.63 years) volunteered for this study. Subjects completed a practice trial of 6 minutes of both forward and retrograde stepping at Level 5. Each experimental trial was divided into four 3-minute stages: Level 3, Level 5, Level 7, and Level 9. Heart rate, blood pressure, and rating of perceived exertion (RPE) were recorded during the second minute of each stage. Expired gases were analyzed and averaged over the last 2 minutes of each stage. Caloric expenditure and delta efficiency were later calculated. Data were analyzed using a 2 x 4 ANOVA (direction by level) and 2 x 3 ANOVA (for delta efficiency). Compared to forward responses, retrograde heart rates were significantly higher at Levels 7 and 9 (p < 0.01). Retrograde responses for RPE, metabolic equivalents (METS), and caloric expenditure were significantly higher at (p < 0.01) Levels 5, 7, and 9 when compared to forward responses. However, the results of this study show that these differences between forward and retrograde stepping are not practically meaningful.

Adult↗
PubMed1992

The reliability and validity of the 20-meter shuttle test in American students 12 to 15 years old.

The purpose of this study was threefold: to determine (a) the test-retest reliability of the 20-m shuttle test (20 MST) (number of laps), (b) the concurrent validity of the 20 MST (number of laps), and (c) the validity of the prediction equation for VO2max developed by Léger, Mercier, Gadoury, and Lambert (1988) on Canadian children for use with American children 12-15 years old. An intraclass coefficient of .93 was obtained on 20 students (12 males; R = .91 and 8 females; R = .87) who completed the test twice, 1 week apart (MT1 = 47.80 +/- 20.29 vs. MT2 = 50.55 +/- 22.39 laps; p > or = .13). VO2peak was obtained by a treadmill test to volitional fatigue on 48 subjects. The number of laps run correlated significantly with VO2peak in males (n = 22; r = .65; F [1, 20] = 14.30 p < or = .001), females (n = 26; r = .51; F [1, 24] = 8.34; p < or = .01), and males and females = (r = .69; F [1, 46] = 42.54, p < or = .001). When the measured VO2peak (M = 49.97 +/- 7.59 ml.kg-1.min-1) was compared with the estimated VO2max (M = 48.72 +/- 5.72 ml.kg-1.min-1) predicted from age and maximal speed of the 20 MST (Léger et al., 1988) no significant difference was found, t (47) = -1.631; p > or = .11, between the means; the r was .72 and SEE was 5.26 ml.kg-1.min-1.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

Separate and sequential effects of exercise and meal ingestion on energy expenditure.

The present study was undertaken to determine whether or not untrained, non-obese college-aged females (n = 10) would exhibit a greater thermic response when exercise (E) (treadmill walking at 56% VO2max) preceded a meal (F) [3,846 kJ (920 kcal), 60% carbohydrate, 25% fat, and 15% protein] (EF) compared with exercise only (ENF) or a meal alone (NEF). A protocol in which neither exercise nor food (NENF) was present served as a baseline. Energy expenditure during 60 min of recovery increased 21.5% for the NEF condition, did not change in the ENF condition, and increased 20% in the EF condition over the corresponding resting metabolic rate. It was concluded that there was no interactive thermic effect from the exercise food sequence above the thermic effect of the meal alone.

Adult↗
PubMed1991

Body composition and sexual maturation in premenarcheal athletes and nonathletes.

The purpose of this study was to compare premenarcheal athletes (A) and nonathletes (NA) in terms of body composition and sexual maturation and to discern the relationship between these variables. Percent body fat (%BF) was determined by the three-component system of Siri utilizing body density from hydrostatic weighing and total body water measured by deuterium oxide dilution. Sexual maturation was self-assessed using the system described by Marshall and Tanner. ANOVAs and polynomial regression analysis revealed that both the A (N = 73) and NA (N = 53) showed similar values and linear increases (P less than 0.001) in height (HT), weight (WT), breast (B) and pubic hair (PH) development from 7 to 15 yr but not in %BF (XA = 15.7 +/- 4.6; XNA = 20.5 +/- 6.4 (P less than 0.001]. The NA exhibited a quadratic curve (P less than 0.01) in %BF over age, while the A showed a negative linear relationship (P less than 0.001) with age. Scheffe post hoc tests revealed significant differences (P less than 0.03, A less than NA) at 11 and 12-15 yr. When %BF was compared to maturation, the A were found to have less fat (P less than 0.01) at stages 1 and 4 of PH and at stages 2, 3, and 4 of B. There were no significant differences between A and NA in the age at which B2, 3, or 4 or PH2, 3, or 4 occurred. Both groups exhibited similar and significant correlations between age, HT, WT, B, and PH development but not %BF.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1990

Passing rates of American children and youth on the FITNESSGRAM criterion-referenced physical fitness standards.

The purpose of this study was twofold: (1) to determine the percentage of 6-18-year-old students who passed the FITNESSGRAM criterion scores for percent body fat (%BF), body mass index (BMI), mile run (MR), sit-ups (SU), pull-ups (PU), and sit and reach (S&R), and (2) to suggest and illustrate the instructed-uninstructed/mastery-nonmastery technique for the validation of criterion-referenced cut-off scores. The data base consisted of the NCYFS I and II national probability samples of students. Results showed that the most frequently passed item was the S&R (M = 90%; F = 97%), followed by the two body composition items (%BF: M = 89%; F = 91%) (BMI: M = 88%; F = 85%), the MR (M = 77%; F = 60%), SU (M = 65%, F = 57%), and finally the PU (M = 73%; F = 32%). It is recommended that the criterion cut-off scores be statistically validated using the illustrated technique when the active (instructed) group has been trained with documented levels of frequency, intensity, and duration and the inactive (uninstructed) group is truly sedentary.

Adipose Tissue↗
PubMed1989

Somatotypes of premenarcheal athletes and non-athletes.

One-hundred thirty-four premenarcheal girls between the ages of 7 and 15 years were somatotyped according to the Health-Carter technique. Sexual maturation was determined by self-assessed Tanner stages. Statistical analysis was completed on 50 athletes (representing seven sports) and 29 non-athletes over the age of 10 years. The mean somatotype for the athletes was calculated to be 2.4-3.6-3.9 and for the non-athletes 3.7-3.7-3.6. Single component ANOVA's revealed that the athletes were significantly less endomorphic (p less than 0.01) than the non-athletes. The overall somatotype ratings and the equality of dispersion about the means were significantly different between the athletes and non-athletes. The single highest category for the athletes was mesomorph-ectomorph and for the non-athletes, mesomorphic-endomorph. Significant negative correlations were obtained between mesomorphy and breast development (-0.33, p less than 0.05) and mesomorphy and pubic hair development (-0.44, p less than 0.01) for the athletes. Significant positive correlations were obtained between endomorphy and breast development (0.55, p less than 0.01) and endomorphy and pubic hair development (0.45, p less than 0.05) for the non-athletes. The mean somatotype for the gymnasts was 2.1-3.9-3.6 and for the swimmers 2.5-3.4-4.1. These two groups were significantly different from each other on each separate component and overall somatotype, but not in equality of dispersion. The results support the conclusion that premenarcheal athletes are morphologically different from non-athletes despite their youth and from each other based on sport specificity.

Adolescent↗
PubMed1988

Leg power characteristics of female firefighter applicants.

The primary purposes of this study were to characterize the anaerobic power of a large group of adult female subjects and to analyze the relationship of body composition, leg power, and leg strength tests to performance on the Wingate Anaerobic Test (WAT) in these women. A secondary purpose was to observe the relationship of the WAT to a stair-climbing test used to select firefighters. The subjects were the top 150 of the 1,090 women who took a firefighter applicant physical performance test. Predicted dependent variables from the WAT were mean power (MP), peak power (PP), and percent fatigue (%F). Among the nine independent variables entered into multiple regression analysis (age, height, weight, fat-free weight, percent fat, leg press strength, vertical jump, maximal physical work capacity (PWCmax) and stair climb) 45%, 40%, and 16% of the variance in MP, PP, and %F were accounted for. Fat-free weight accounted for the most variation in MP and PP, and PWCmax accounted for the most variation in %F. There was little relationship observed between MP, PP, or %F and the stair-climbing test.

Body Composition↗
PubMed1988

Exercise during gravity inversion: acute and chronic effects.

The purpose of this study was to determine whether gravity inversion could correctly be called an exercise, and whether inversion and inverted exercise produced safe blood pressure responses. Systolic blood pressure (SBP), diastolic blood pressure (DBP), heart rate (HR), and oxygen consumption (VO2) were measured in 19 healthy young men (means = 20.31 years) in seven positions: (1) standing passive (STD), (2) inverted passive (INV), (3) standing recovery postpassive inversion (SRPI), (4) standing exercise (SDE), (5) standing recovery poststanding exercise (SRPSE), (6) inverted exercise (INVE), and (7) inverted recovery postinverted exercise (IRPIE). Ten of the subjects participated in a five-week inversion training program, after which all 19 subjects were retested. Compared to STD, INV elicited significant increases in SBP/DBP and a significant decrease in HR. The average INV blood pressure was 146/97 mmHg, which was further increased during INVE to 158/101 mmHg. These responses increase the workload of the heart and may be dangerous to some populations. No physiologic adaptations occurred in any of the inverted positions as a result of inversion training. Gravity inversion should not be compared to or classified as an exercise. Some previously suggested inverted exercises are not recommended. Because of the nature of the responses, medical screening before the use of inversion devices is critical.

Adult↗
PubMed1987

Performance differences between males and females on simulated firefighting tasks.

Males and females were compared on several physical performance test items. The tests included five tasks used by the City of Chicago to select firefighters as well as four new test items that were designed to reflect recent changes in firefighting procedures. Sixty-two subjects (37 males, 25 females) 17-31 years of age were tested twice with 1 week intervening on a battery of tests that included measurements of body size and composition and the nine physical performance tests. Results indicated that the tests were reliable, but substantial improvement was observed on all items from the first test to the second test. Also, fatness was found to have a negative influence on physical tasks in which the body weight was translocated either vertically or horizontally; conversely, fat-free weight had a positive influence on performance in tasks requiring application of force such as lifting, carrying, and striking activities. Finally, females demonstrated lower scores than males on all physical performance items.

Adolescent↗
PubMed1979

Age and aerobic power in women: a longitudinal study.

Thirty-six women from an original cross-sectional population of 81 were retested after an average time span of 6.1 years to determine the longitudinal effects of aging on aerobic power. Women in their 20s maintained a constant level of VO2max. All other age groups showed a decrease in aerobic power (l . min-1 and ml . kg-1 . min-1) similar to that observed in the cross-sectional study. Although the decline in VO2max was similar for both groups, active women increased walk time on the treadmill, while sedentary women decreased in endurance time. Maximal heart rate also decreased with age but the rate of decrease was not constant across time. HRmax remained relatively steady during the middle years and then declined at a faster rate in the 50- and 60-year-old age groups. The results of the present study suggest that cross-sectional studies can provide valid information about the effect of age on response to maximal exercise provided that close attention is paid to the limitations underlying regression therapy. The data also indicate a need to consider alternatives to linear regression analysis of aging effects, since the rate of change of some variables is not constant across age.

Adolescent↗
PubMed1979

Response of women mountaineers to maximal exercise during hypoxia.

Eight members of the American Women's Himalayan Expedition, ranging in age from 20-49, performed maximal exercise on a treadmill under normoxic and acute hypoxic (12.58% O2) conditions. Normoxic values for VO2 max were above average for all subjects and did not decline with age. The mean decrease in VO2 max (26.7%) during hypoxia was equivalent to that reported for younger males, which suggests that age was not a factor in response to hypoxia. Maximal heart rate, respiratory exchange ratio, oxygen pulse, and walk time were lower in hypoxia while ventilatory equivalent and blood lactate were higher. VEmax BTPS, was the same under both conditions. The combination of laboratory results and field observations by the Expedition physician suggest that women are capable of performing hard work at high altitude if they are in good condition and properly acclimatized.

Adult↗