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Biomedical subjects

P Freedson

Publications and source records attributed to P Freedson.

12 recordsLinked to original sources
PubMed2000

Validity of accelerometry for the assessment of moderate intensity physical activity in the field.

PURPOSE: This study was undertaken to examine the validity of accelerometry in assessing moderate intensity physical activity in the field and to evaluate the metabolic cost of various recreational and household activities. METHODS: Twenty-five subjects completed four bouts of overground walking at a range of self-selected speeds, played two holes of golf, and performed indoor (window washing, dusting, vacuuming) and outdoor (lawn mowing, planting shrubs) household tasks. Energy expenditure was measured using a portable metabolic system, and motion was recorded using a Yamax Digiwalker pedometer (walking only), a Computer Science and Application, Inc. (CSA) accelerometer, and a Tritrac accelerometer. Correlations between accelerometer counts and energy cost were examined. In addition, individual equations to predict METs from counts were developed from the walking data and applied to the other activities to compare the relationships between counts and energy cost. RESULTS: Observed MET levels differed from values reported in the Compendium of Physical Activities, although all activities fell in the moderate intensity range. Relationships between counts and METs were stronger for walking (CSA, r = 0.77; Tritrac, r = 0.89) than for all activities combined (CSA, r = 0.59; Tritrac, r = 0.62). Metabolic costs of golf and the household activities were underestimated by 30-60% based on the equations derived from level walking. CONCLUSION: The count versus METs relationship for accelerometry was found to be dependent on the type of activity performed, which may be due to the inability of accelerometers to detect increased energy cost from upper body movement, load carriage, or changes in surface or terrain. This may introduce error in attempts to use accelerometry to assess point estimates of physical activity energy expenditure in free-living situations.

Activities of Daily Living↗
PubMed1998

Improved psychological well-being, quality of life, and health practices in moderately overweight women participating in a 12-week structured weight loss program.

OBJECTIVE: To study the effects of a 12-week weight loss strategy involving increased physical activity, self-selected hypocaloric diet, and group support on psychological well-being, quality of life, and health practices in moderately obese women. METHODS: Eighty women aged 20-49 years weighing between 20-50% above 1983 Metropolitan Life Insurance Tables were randomly assigned to a weight loss intervention (6279 kJ/week of physical activity, 33,258-41,462 kJ/week diet and weekly meetings) or served as controls. Subjects were tested pre and post 12-weeks. RESULTS: The intervention group lost significant (p<0.001) body weight (kg) and body fat (%) compared to controls (-6.07+/-4.01 kg vs. 1.31+/-1.28 kg; 36.8%-32.5% vs. 36.2%-36.0%). Intervention subjects vs. controls achieved significant improvements (p<0.001) in body cathexis (X Change 18.6+/-16.7 vs. 0.7+/-8.6) and estimation of ability to achieve physical fitness (X Change 8.1+/-7.1 vs. 0.9+/-5.9). Various quality of life indices also improved (p<0.01) in the intervention group compared to controls (physical function: X Change 13.5.2+/-16.7 vs. 1.4+/-9.5; vitality: X change 21.7+/-17.9 vs. 2.9+/-20.8; mental health: X change 10.4+/-16.0 vs. 2.3+/-10.1). Similarly, physical activity levels also improved significantly (p<0.0001) in the intervention group (4.4+/-2.3 vs. 0.6+/-1.3; on NASA 0-7 scale). CONCLUSIONS: Practical weight loss practices such as increased activity, self-selected hypocaloric diet, and group support are effective for weight loss and yield significant health and psychological benefits in moderately obese females.

Adult↗
PubMed1982

Biological variability in maximum aerobic power.

The biological variation in maximum aerobic power (V O2max) was examined in four trained females and one trained male. An average of 8-20 repeat VO2max treadmill tests over a 2-4 wk period were performed on each subject (80 total tests). Biological variation (Si) in VO2max was computed as the standard deviation for the VO2max values for each individual, after subtracting net technological error (Se). Technological error was computed for each piece of equipment as the standard deviation of multiple trials. Results revealed that Si + Se amounted to +/- 5.6%. Biological variability accounted for 90% or more of this variability, while technological error accounted for less than 10%. In light of the magnitude of biological variation for VO2max, the necessity for securing control data when attempting to study training effects is pointed out.

Adult↗
PubMed1980

Contribution of breast volume and weight to body fat distribution in females.

Breast volume and body composition were measured in 45 adult females to determine the contribution of breast weight and breast volume to total body fat. Plaster casts were filled with sand of known density to obtain breast volume. Breast weight was computed as breast volume times its density. The correlation between total breast volume and percent body fat was r = .40. Breast weight (mean = 484 grams) accounted for 3.5 percent of the total weight of body fat, and at most, 12 percent of the estimated quantities of sex-specific fat. A theoretical model is proposed for the distribution of body fat in the female which subdivides total body fat into three components: reserve storage fat, essential fat, and expendable storage fat.

Adipose Tissue↗
PubMed1980

Body composition of synchronized swimmers.

The body composition of 15 synchronized swimmers and 15 non-athletic female controls were compared. Body fat and lean body weight were calculated from body density measurements. Swimmers were ranked according to skill level and ability in an attempt to predict success in synchronized swimming from percent body fat or lean body weight. A student t-test revealed no statistically significant differences between groups for height, weight, percent body fat or lean body weight. Non-significant rank order correlations between ability ranking and percent fat (r = -.31) and lean body weight (r = -.18) point to the inability to predict success in synchronized swimming from these variables. These data were compared with female athletes of other sports.

Adult↗
PubMed1979

Cardiac output differences in males and females during mild cycle ergometer exercise.

To study sex differences in cardiac output during submaximum exercise, eight male and eight female subjects were matched on max Vo2 (1 min-1 and ml kg-1 min-1). Each subject performed one, eight minute submaximum bicycle ergometer test at 35% of Vo2max (300 kpm min-1). At a steady state mean Vo2 of 0.96 1 min-1, cardiac output was determined. Significant differences between men and women were observed (p less than .05) in cardiac output, stroke volume and (a-v) O2 difference. The males had a lower cardiac output (1.75 1 min-1) and stroke volume (17.2 ml beat-1) and a higher (a-v) O2 difference (2.01 vol %). When these variables were expressed independent of lean body weight the above differences were non-significant. It was suggested that cardiac output differences between the sexes during mild exercise are due, in part, to differences in lean body weight.

Adult↗
PubMed1978

Validity of the relative percent concept for equating training intensity.

The validity of the relative percent concept for equating training intensity was investigated using the point of metabolic acidosis (anaerobic threshold) as the criterion variable. Percent oxygen uptake, heart rate and metabolic acidosis were determined at 60, 70, and 80% of max heart rate on a bicycle ergometer test(N = 31). At 60 and 70% of max heart rate only one individual was definitely in metabolic acidosis. At 80% max heart rate 17 subjects were working at a level above the point of metabolic acidosis while 14 were working at or below this point. Thus, it was suggested that even if subjects are exercising at the same relative percent miximum HR, the metabolic stress using metabolic acidosis as the criterion is not constant across subjects. It was further shown that the regression of percent VO2 max on percent max HR was a spurious one resulting in poor prediction of individual VO2 values. The data presented suggest that the relative percent concept for equating exercise or subsequent training intensity needs careful re-evaluation.

Acidosis↗
PubMedDate not supplied

Measurement of breast volume in females: description of a reliable method.

Breast volume measurements were made on 47 adult subjects using a casting method. After drying, fast-setting plaster casts were filled with sand of known density to a level approximating the curvature of the chest wall. The reliability of both sand filling and casting proved to be high, r = 0.97, and r = 0.99, respectively. The total variable error was 10.2%. The effects of position (standing versus lying) was investigated in a separate sample of 15 subjects. No significant difference (P less than 0.05) was found between methods. The relationship between breast volume, girths, skinfolds, and body density was reported to be low.

Adolescent↗