Comparison of existing skinfold equations for estimating body fat in African American and white women.

The purpose of this study was to compare seven skinfold equations with underwater weighing (UWW) for estimating body fat in 39 African American [age: 22.8 +/- 3.6 y (x +/- SD); weight: 59.6 +/- 8.3 kg) and 39 white (age: 22.1 +/- 2.9 y; weight: 61.7 +/- 7.3 kg) women. The hypothesis examined was that the equations would produce more accurate body fat estimates in white women, but would be appropriate for use in African American women. Body fat estimated from two quadratic, three linear, and two logarithmic skinfold equations was compared with body fat estimated from UWW; the same procedures were used to evaluate the results in both African Americans and whites. The data were analyzed by using t tests, analysis of variance, Scheffé's honestly significant difference tests, correlations, error assessments, and agreement. The results showed that total error, SEE, and SD values were larger in the African American women than in the white women and were not within acceptable limits listed in the literature. The correlation coefficients were lower in the African American women than in the white women. Agreement between the skinfold equations and UWW, based on deviations from mean differences, was better in the white women. In conclusion, the skinfold prediction equations evaluated in this study were more variable and produced more error when used in African American women. Therefore, population-specific equations for African American women should be used to estimate body fat because they will probably yield more accurate estimates.

Body composition and blood pressure in children based on age, race, and sex.

We evaluated 675 nine- and twelve-year-old children for body composition and circulatory differences based on age, race, and sex. The specific variables measured included height, weight, triceps and subscapula skinfolds, body mass index, percentage fat, fat-free weight, and systolic, diastolic, and mean arterial blood pressures. A 2 x 2 x 2 factorial multiple analysis of variance (MANOVA) test of significance showed body composition and blood pressure differences (P < .01) for race, age, and sex. The univariate test of the specific variables within the factors showed that black children had higher fat-free weights and lower fat levels but higher blood pressure values (P < .05) than white children. Boys had lower fat levels than girls, and the older children had higher values on the body composition variables but not on blood pressure. Zero order correlations between body composition and blood pressure ranged from 0.14 to 0.55; systolic blood pressure and body weight shared the highest correlation. These data show that, although black children have less body fat than white children, they are heavier and have higher blood pressure. We hypothesize that some aspect of fat-free body weight may contribute to hypertension in black individuals.

Physiological factors associated with middle distance running performance.

Middle distance running involves popular race distances with performance dependent on a number of physiological factors. The physiological characteristics of successful runners are different from those of sprinters and long distance runners. Maximal oxygen uptake (VO2max), running economy and the anaerobic threshold are variables that have been shown to limit performance during long distance running, and rapid velocity and anaerobic variables have been shown to limit performance during sprinting. Success with middle distance running is dependent on an integrative contribution from aerobic and anaerobic variables which allows a runner to maintain a rapid velocity during a race. The relative contributions of the 2 energy systems are functions of distance, intensity and the physiological abilities of the runner. Middle distance runners can be successful with physiological profiles that include a variety of aerobic and anaerobic capabilities, and this characteristic separates them from long distance runners.

Methodological factors and the prediction of body fat in female athletes.

The effect of skinfold caliper, investigator technique, and various skinfold prediction equations on estimates of body fatness was investigated using college-age female basketball players. Four skinfold calipers, four investigators, and five prediction equations from the literature were selected for study. Skinfolds were obtained on 16 athletes for each of five sites by all four investigators using each caliper. Triceps and subscapular skinfolds showed less variation among investigators (mean differences of 1-4 mm) as compared to suprailiac, abdomen, and thigh skinfolds (mean differences of up to 5-6 mm). Differences among investigators were less using the Harpenden and Holtain than for the Lange and Adipometer calipers. All three sources of variation--caliper, investigator, and prediction equation--contributed significantly to the variability in estimates of mean fat content of this sample, which ranged from 14.1-28.1% depending on which of the 80 caliper-investigator-prediction equation combinations (four calipers, four investigators, and five equations) was used. Using any one prediction equation, the range in mean percent fat due to the 16 caliper-investigator combinations was 7%. The results illustrate the need for standardization of skinfold sites, caliper, and prediction equations for reliable estimation of body composition in a specific population.

Health fitness training responses of normotensive and elevated normotensive children.

Abstract The purpose of this study was to compare health fitness profiles of normotensive (blood pressure < 108/76) and elevated normotensive (blood pressure ≥ 108/76) children and to evaluate the health fitness training responses of children with higher and lower blood pressures to a regular program of exercise over an eight month period. The subjects were 386 fourth grade students (lower blood pressures = 305; higher blood pressures = 81). They were measured for height and weight and evaluated before and after an exercise intervention program for flexibility, muscular endurance, cardiovascular endurance, and body fat levels. The results show that children with higher blood pressures were fatter and had lower cardiovascular fitness levels before and after the intervention. They had health fitness profiles similar to hypertensive adults. Their rate of health fitness improvement, with training, was similar to children with lower blood pressures. Therefore, elevated normotensive children have an increased risk of cardiovascular disease but can change their risk profile with regular exercise.

Are practical methods of evaluating body fat in African-American women accurate?

Sixteen African American females were evaluated for body fat to assess the accuracy of several practical methods of estimation: near-infrared interactance, bioelectrical impedance, and Sloan and Jackson skinfold equations. Most methods produced different results from hydrostatic weighing and produced different body fat values from each other suggesting that practical methods do not provide accurate measurements.

Exercise adherence for a strength training program in older adults.

The first purpose of the present investigation was to examine initiation of a moderate intensity strength training and flexibility program in older adults. The second purpose was to assess adherence to training six months after conclusion of the initiation period. Forty-six apparently healthy older adults (mean age = 71.3; 33 women; 13 men) trained one hour, three days a week, for 4 months on a Nautilus Multi-Station Unit. The subjects trained on five upper extremity, three trunk, and three lower extremity stations. Training sessions consisted of 50 minutes of strength training and 10 minutes of flexibility exercises. Baseline exercise habits were obtained from the subjects using the Physical Exercise Profile (PEP). Subjects also completed portions of the PEP immediately following the conclusion of the 4-month intervention and 6 months later. The data were analyzed by chi square contingency tables. The subjects had over a 95% initiation rate during the study. Exercise leadership and program organization were found to be the most important reasons for the high initiation rate. Two determinants that influenced older adults to continue training were identified: satisfaction with the exercise routine and body image. These results indicate that exercise programs designed for older adults should emphasize exercise leadership to facilitate program initiation and subsequent exercise adherence.

Effects of a four-month strength training program on blood pressure in older adults.

The purpose of this study was to evaluate the effects of a 4-month strength training program on strength and blood pressure (BP) in older adults. The training protocol for the 43 experimental subjects (ES) (age 72.1, Sd 5.5 yr; Wt 72.4, Sd 12.3 kg; BMI 26.3, Sd 3.4) consisted of 8-12 reps at each of 50, 60 and 70% of their one repetition maximum (1RM), three days a week, for 16 weeks. The subjects trained on five upper extremity, three trunk, and three lower extremity muscle groups. They were evaluated for 1RM initially, after 3, 5, 7, 12, and 16 weeks of training. Daily systolic (SBP), diastolic (DBP) and mean arterial blood pressures (MABP) were averaged to produce BP values for baseline, weeks 3, 5, 7, 9, 12, and 16. Eighteen comparison subjects (age 71.8, Sd 4.6 yr--(CS)) were evaluated for strength and BP before and after the 4-month intervention period. The data were evaluated for differences by ANOVA, Scheffe' HSD tests and Pearson correlation coefficients. Baseline and 3, 5, 7, 9, 12, and 16 week BPs were evaluated for changes over time and relationships with trunk, upper, and lower extremity strength measurements for the ES. Following training, there was an overall increase in strength of 45% and each segment increased significantly (p<0.05). Systolic blood pressure remained unchanged, while MABP and DBP decreased 2.4 and 3 mmHg, respectively. Strength and BP shared significant, but moderate relationships before and after the training intervention. These results show that moderate intensity strength training greatly improved strength in older adults and had no adverse affect on BP responses.

A follow-up study on the effects of strength training with older adults.

This study was designed to evaluate changes in strength, and functional ability in older adults after completion of a 4-month strength training intervention. The follow-up sample consisted of 30 older adults (12 men and 18 women, 100% Caucasian; mean age = 71.8) who were evaluated an average of 15 months after completion of the training intervention. At the follow-up testing, 45% of the subjects reported that they continued strength training on their own after the conclusion of the strength training intervention. The data were evaluated for pre-, post-training, and follow-up differences via repeated measures ANOVA and Scheffé HSD tests. After the intervention, the subjects showed significant improvement in muscular strength and one of the functional tasks measuring coordination. From post- to the 15 month follow-up, the subjects declined in muscular strength and functional ability (mobility). However, at follow-up the subjects were stronger and had better coordination than before they entered the strength training intervention. These results suggest benefits were retained 15 months after the strength training intervention in a sample of relatively healthy older adults.

Older adults' experiences of a strength training program.

Despite the recognized benefits of strength training in preventing physical and functional decline among older adults, little information exists on their views of this exercise modality. This study used focus groups to obtain an in-depth understanding of older adults' attitudes and concerns about a strength training intervention and to identify factors that determined their adherence to this exercise program. Three focus groups were conducted with 24 former participants after the completion of the 16-week intervention. Major themes that emerged from the focus group discussions were categorized according to Dishman, Sallis, and Orenstein's [1] framework of factors influencing adherence, including personal, activity, and environmental characteristics. The most frequently reported factors were enjoyment of strength training, accessibility of the exercise facility, and the social reinforcement provided by exercise leaders and partners. Recommendations for strength training program development with older adults are discussed in light of these factors.

Effects of resistive training on strength gains in older adults.

This study was designed to evaluate the effects of a moderate intensity, 16-week resistive strength training program on the rate and pattern of strength changes in trunk, upper, and lower extremity muscle groups. This study was also designed to determine the importance of muscle mass on strength gains during a training intervention with older adults. A repeated measures experimental design was employed with 43 experimental (ES) and 42 comparison subjects (CS). The active older sample had a relatively high level of strength for their age (72.1 yr) and had no contraindications for strength training. The ES trained five upper, three trunk, and three lower extremity muscle groups. Both ES and CS received pre- and post-testing assessments for muscle strength, muscle morphology, body composition, flexibility, and balance. The ES also received intermittent testing for one repetition maximum (1RM). ANOVA and Scheffé HSD tests were used to evaluate the data. The ES experienced significant strength gains (over 41% for each body segment) following the intervention. The rate of gain in this study was less than but the absolute strength gain was reasonably similar to values reported by studies in the literature [1,2]. There was no change in muscle mass (p>.05) following training. These results suggests that stronger active older adults have a muscle mass sufficient for greater strength and that training enables them to use available muscle mass more effectively. These results further suggest that muscle hypertrophy may be possible following strength training but it is not always necessary for strength improvement in older adults.

Influence of metabolic, mechanical and physique variables on middle distance running.

The purpose of this study was to determine the variables that most limit middle distance run performance e.g. 800, 1500 and 3000 meters. A predictive research design was employed as 56 runners ran each of the three distances and were evaluated for VO2max, running mechanics, physique variables, ventilatory threshold, and anaerobic capacity and power. The data were analyzed by correlation procedures and stepwise regression analysis. The variables that most limited 1500 and 3000 meter (m) run performance were identical. Maximal oxygen uptake was the most important, but stride length and anaerobic capacity and power also contributed significantly. Run performance at 800 m was influenced by a considerably different set of variables. Peak velocity was most important, but VO2max, % fat and thigh length also contributed significantly. These data indicate that 1500 and 3000 m runners can compete favorably at either distance, while 800 m runners have a different profile and would experience difficulty competing at 1500 and 3000 meters.