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Biomedical subjects

J M Pivarnik

Publications and source records attributed to J M Pivarnik.

At least 19 recordsLinked to original sources
PubMed2004

Changes in von Willebrand factor and fibrinolysis following a post-exercise cool-down.

The purpose of this study was to determine the effect of a post-exercise active cool-down on von Willebrand factor and fibrinolysis. Ten subjects performed two maximal oxygen uptake (VO2max) tests followed by a 10-min passive (PC) or an active (AC) cool-down. Blood samples were obtained pre-exercise, post-exercise, post-PC/AC, and 1 h post-exercise and analyzed for von Willebrand factor antigen (vWf:Ag), tissue plasminogen activator (tPA) antigen and activity and plasminogen activator inhibitor-1 (PAI-1) activity. Data were analyzed using repeated measures analysis of variance. No significant differences were found between VO2max tests for treadmill time, VO2max, respiratory exchange ratio, maximal heart rate, or maximal blood lactate concentration. vWf:Ag was significantly elevated (P <0.05)following PC [198.4 (18.3)% normal] versus AC [174.5 (15.6)% normal] and remained elevated 1-h post-exercise [179.4 (16.4)% normal for PC vs 158.6 (13.8)% normal for AC]. There were no differences between tests for tPA or PAI-1 activity, although tPA antigen was significantly elevated following PC versus AC (P <0.05). Following the cool-down, hematocrit was higher (P <0.05) for the PC test [48.90 (0.36)] compared with AC [47.43 (0.51)]. An AC reduces post-exercise vWf:Ag and tPA antigen without affecting tPA or PAI-1 activity.

Adaptation, Physiological↗
PubMed2001

Blood lipids of young distance runners: distribution and inter-relationships among training volume, peak oxygen consumption, and body fatness.

This study describes the distribution of blood lipid concentrations and examines relationships among training volume (TV, kilometers per week), peak oxygen consumption (VO2peak), body fatness, and blood lipid concentrations in 48 male and 22 female distance runners, aged 10-19 years. Comparisons were made to a current reference sample and clinical cut-off points. Relationships were assessed by partial correlations allowing for age and sexual maturity. Compared to reference median values, mean concentrations of total cholesterol (P=0.07) and low density lipoprotein-cholesterol (P<0.005) were higher, while high density lipoprotein-cholesterol (HDL-C; P=0.24) was comparable in male distance runners. Blood lipid concentrations in female distance runners were comparable to reference median values. Although some subjects had dyslipidemic values, most possessed clinically normal concentrations of blood lipids. The TV was weakly correlated with blood lipid concentrations, but may have been indirectly related with HDL-C through its relationship with VO2peak in males runners (r=0.32). In female runners, correlations between sum of skinfolds (SSF), the trunk-to-extremity ratio (TER) and blood lipid concentrations were low (r=0.16 to -0.27), with one exception (TER and HDL-C, r=-0.60). The most consistent relationships existed among TV, VO2peak, SSF, and HDL-C with partial correlations ranging from low (r=0.10 TV) to moderate (r=0.37 SSF, r=0.41 VO2peak). The correlation between VO2peak and HDL-C remained significant after allowing for age and SSF, while the partial correlation between SSF and HDL-C, allowing for age and VO2peak, was reduced and not significant (r=-0.19, P=0.20). In female runners, the correlation between VO2peak and HDL-C was r=0.32, whereas the partial correlation between SSF and HDLC, allowing for age and VO2peak, was r=0.00. Blood lipid concentrations of young male distance runners were not, on average, different to the general population of the youth of the United States. The young distance runners showed considerable heterogeneity in blood lipid phenotypes, including dyslipidemic values. The results highlight the complex relationships among TV, VO2peak, body fat and HDL-C, and indicate the unique contribution of VO2peak as an important predictor of HDL-C in young distance runners.

Adolescent↗
PubMed2001

Training patterns of athletes during pregnancy and postpartum.

The purpose of the present investigation was to examine exercise patterns and psychological variables mediating a return to training and competition after pregnancy. Competitive female athletes who had given birth within the last 10 years completed surveys concerning (a) training patterns before, during, and after childbirth, (b) childbirth complications and training advice, (c) perceptions of success in their postpartum comebacks to training, and (d) self-efficacy, social support, and perceived barriers to training during pregnancy and after childbirth. Results indicated that women decreased both cardiovascular and resistance training during pregnancy. Additionally, training efforts during pregnancy were independent of those during the pre- and postpartum periods. This finding suggests that athletes may be able to alter their training patterns during pregnancy without a significant impact on their postpartum training program.

Adult↗
PubMed2001

Stability and convergent validity of three physical activity assessments.

PURPOSE: The purpose of this study was to examine the stability and convergent validity of heart rate (HR) monitoring, Caltrac accelerometer, and physical activity recall (PAR) in sixth-grade girls during normal weekday activities. METHODS: 46 sixth-grade girls (age 12 +/- 0.6) wore HR monitors and Caltrac accelerometers for 3 d during school, after school, and evenings. We also obtained a PAR for each day. Data were compared on the basis of kcal x h(-1). RESULTS: Two days' worth of data were analyzed for each participant. Intraclass correlation coefficients obtained by use of repeated measures ANOVA revealed that HR monitoring (r = 0.99) and PAR (r = 0.98) were extremely stable across 2 d, whereas Caltrac was moderately stable (r = 0.76). Pearson correlations between techniques were HR versus PAR, r = 0.50 (P < 0.01), HR versus Caltrac, r = 0.28, and Caltrac versus PAR, r = 0.76 (P < 0.01). Methods comparison plots showed poor individual subject agreement between all three types of assessment. CONCLUSION: HR and PAR were stable across 2 d. PAR underestimated caloric expenditure by approximately 14%. Caltrac showed the least utility in both reliability and validity.

Analysis of Variance↗
PubMed2001

Blood lipids in young distance runners.

PURPOSE: The purpose of this study was to examine the age-and sex-associated variation in blood lipids among young athletes. METHODS: A mixed-longitudinal design was used to examine the development of blood lipids in competitive young distance runners followed from 1982 to 1985. Serial data included 99 annual measurements for 27 male subjects and 84 annual measurements for 27 female subjects aged 9-18 yr. Total cholesterol (TC), high-density lipoprotein (HDL-C), low-density lipoprotein (LDL-C), and triglycerides (TG) were determined by standard procedures. RESULTS: In general, cross-sectional age group means showed that TC and LDL-C remained stable and HDL-C declined with age, especially in male subjects. TG increased with age. Age-related trends were statistically significant for HDL-C and TG in boys only (P < 0.05). TC and LDL-C were slightly greater in boys at all ages except 11, 15, and 17 yr (P > 0.05). HDL-C was similar between the sexes until 13 yr when values became greater in girls (3.2-13.8 mg.dL(-1)) (P < 0.05 in 17+ yr). No clear pattern of sex differences emerged for TG. Compared with the general population, blood lipids of young distance runners showed the following trends: 1) TC was above reference medians, 2) LDL-C tended to approximate or to be slightly above reference medians, 3) TG fluctuated about the reference medians, and 4) HDL-C was higher in distance runners compared to the reference medians before age 14 yr, but in the older age groups, especially male subjects, HDL-C either approximated or fell slightly below the reference medians. There was considerable variability in blood lipid levels among the runners. In 21 male and 18 female subjects with serial data for 3-5 yr, HDL-C declined 22.4 and 18.3 mg.dL(-1) (P < 0.05), whereas TG increased 18.0 and 14.0 mg.dL(-1)(P < 0.05 in female subjects only) in male and female subjects, respectively. Tracking coefficients over intervals of 3-5 yr were moderate to high (0.48-0.90), except for TG in male subjects (0.08). CONCLUSIONS: The results indicate that the development of blood lipids in young distance runners is similar to youth in the general population. In contrast to observations in adult endurance athletes, young distance runners did not possess a superior blood lipid profile except for HDL-C in the younger age groups.

Adolescent↗
PubMed2001

Scaling peak VO2 to body mass in young male and female distance runners.

This study examined age- and sex-associated variation in peak oxygen consumption (VO2) of young male and female distance runners from an allometric scaling perspective. Subjects were from two separate studies of 9- to 19-yr-old distance runners from the mid-Michigan area, one conducted between 1982 and 1986 (Young Runners Study I, YRS I) and the other in 1999-2000 (Young Runners Study II, YRS II). Data from 27 boys and 27 girls from YRS I and 48 boys and 22 girls from the YRS II were included, and a total of 139 and 108 measurements of body size and peak VO2 in boys and girls, respectively, were available. Subjects were divided into whole year age groups. A 2 x 9 (sex x age group) ANOVA was used to examine differences in peak VO2. Intraindividual ontogenetic allometric scaling was determined in 20 boys and 17 girls measured annually for 3-5 yr. Allometric scaling factors were calculated using linear regression of log-transformed data. Results indicated that 1) absolute peak VO2 increases with age in boys and girls, 2) relative peak VO2 (ml x kg(-1) x min(-1)) remains relatively stable in boys and in girls, 3) relative peak VO2 (ml x kg(-0.75) x min(-1)) increases throughout the age range in boys and increases in girls until age 15 yr, and 4) peak VO2 adjusted for body mass (ml/min) increases with age in boys and girls. The overall mean cross-sectional scaling factor was 1.01 +/- 0.03 (SE) in boys and 0.85 +/- 0.05 (SE) in girls. Significant age x sex interactions and significant scaling factors between sexes identify the progressive divergence of peak VO2 between adolescent male and female distance runners. Mean ontogenetic allometric scaling factors were 0.81 [0.71-0.92, 95% confidence interval (CI)] and 0.61 (0.50-0.72, 95% CI) in boys and girls, respectively (P = 0.002). There was considerable variation in individual scaling factors (0.51-1.31 and 0.28-0.90 in boys and girls, respectively). The results suggest that the interpretation of growth-related changes in peak VO2 of young distance runners is dependent upon the manner of expressing peak VO2 relative to body size and/or the statistical technique employed.

Adolescent↗
PubMed2000

Treadmill economy in girls and women matched for height and weight.

We investigated differences in walking (80 m/min) and running (147 m/min) economy [submaximal oxygen consumption (VO(2) (submax))] between adolescent girls (n = 13; age = 13.3 +/- 0.9 yr) and young women (n = 23; age = 21.0 +/- 1.5 yr). Subjects were matched for height (158.7 +/- 2.9 cm) and weight (52.1 +/- 3.0 kg). Anthropometric measures (height, weight, breadths, skinfolds) and preexercise oxygen consumption were obtained on all subjects before submaximal and maximal treadmill exercise. Anthropometric measures were similar between groups, as was maximal oxygen consumption (girls, 47.7 +/- 5.2; women, 47.5 +/- 5.7 ml. kg(-1). min(-1)). VO(2) (submax) was significantly greater (P < 0.0002) in girls compared with women during both walking (16.4 +/- 1.7 vs. 14.4 +/- 1. 1 ml. kg(-1). min(-1)) and running (38.1 +/- 3.7 vs. 33.9 +/- 2.4 ml. kg(-1). min(-1)). Preexercise oxygen consumption (4.4 vs. 3.9 ml. kg(-1). min(-1)) accounted for only a fraction of the differences found in exercise economy. Although heart rate and respiratory frequency were greater in the girls in both walking (118 +/- 11 vs. 104 +/- 12 beats/min and 31 +/- 3 vs. 25 +/- 4 breaths/min, respectively; P < 0.002) and running (180 +/- 15 vs. 163 +/- 17 beats/min and 47 +/- 11 vs. 38 +/- 8 breaths/min; P < 0.005), this did not likely account for a large part of the difference in VO(2) (submax) between groups.

Adolescent↗
PubMed1999

Reliability and validity of body composition measures in female athletes.

The purpose of this investigation was to determine the reliability and validity of bioelectrical impedance (BIA) and near-infrared interactance (NIR) for estimating body composition in female athletes. Dual-energy X-ray absorptiometry was used as the criterion measure for fat-free mass (FFM). Studies were performed in 132 athletes [age = 20.4 +/- 1.5 (SD) yr]. Intraclass reliabilities (repeat and single trial) were 0.987-0.997 for BIA (resistance and reactance) and 0.957-0.980 for NIR (optical densities). Validity of BIA and NIR was assessed by double cross-validation. Because correlations were high (r = 0.969-0.983) and prediction errors low, a single equation was developed by using all 132 subjects for both BIA and NIR. Also, an equation was developed for all subjects by using height and weight only. Results from dual-energy X-ray absorptiometry analysis showed FFM = 49.5 +/- 6.0 kg, which corresponded to %body fat (%BF) of 20.4 +/- 3.1%. BIA predicted FFM at 49.4 +/- 5.9 kg (r = 0.981, SEE = 1.1), and NIR prediction was 49. 5 +/- 5.8 kg (r = 0.975, SEE = 1.2). Height and weight alone predicted FFM at 49.4 +/- 5.7 kg (r = 0.961, SEE = 1.6). When converted to %BF, prediction errors were approximately 1.8% for BIA and NIR and 2.9% for height and weight. Results showed BIA and NIR to be extremely reliable and valid techniques for estimating body composition in college-age female athletes.

Absorptiometry, Photon↗
PubMed1999

MR measurements of muscle damage and adaptation after eccentric exercise.

The purposes of this study were, first, to clarify the long-term pattern of T2 relaxation times and muscle volume changes in human skeletal muscle after intense eccentric exercise and, second, to determine whether the T2 response exhibits an adaptation to repeated bouts. Six young adult men performed two bouts of eccentric biceps curls (5 sets of 10 at 110% of the 1-repetition concentric maximum) separated by 8 wk. Blood samples, soreness ratings, and T2-weighted axial fast spin-echo magnetic resonance images of the upper arm were obtained immediately before and after each bout; at 1, 2, 4, 7, 14, 21, and 56 days after bout 1; and at 2, 4, 7 and 14 days after bout 2. Resting muscle T2 [27.6 +/- 0.2 (SE) ms] increased immediately postexercise by 8 +/- 1 ms after both bouts. T2 peaked 7 days after bout 1 at 47 +/- 4 ms and remained elevated by 2.5 ms at 56 days. T2 peaked lower (37 +/- 4 ms) and earlier (2-4 days) after bout 2, suggesting an adaptation of the T2 response. Peak serum creatine kinase values, pain ratings, and flexor muscle swelling were also significantly lower after the second bout (P < 0.05). Total volume of the imaged arm region increased transiently after bout 1 but returned to preexercise values within 2 wk. The exercised flexor compartment swelled by over 40%, but after 2 wk it reverted to a volume 10% smaller than that before exercise and maintained this volume loss through 8 wk, consistent with partial or total destruction of a small subpopulation of muscle fibers.

Adaptation, Physiological↗
PubMed1998

Potential effects of maternal physical activity on birth weight: brief review.

This review lists the most commonly accepted risk factors for low birth weight (LBW) and offers critical examination of research on the effect of maternal physical activity, both occupational and leisure time, on birth weight. Some studies have shown job related physical "activity" to be related to unfavorable birth outcomes, including premature delivery and LBW. However, most studies have not controlled for socioeconomic status, nor has actual physical activity been well quantified throughout gestation. Similarly, results of the relationship between leisure time physical activity and birth weight are mixed. Current evidence appears to indicate participation in moderate to vigorous activity throughout pregnancy may enhance birth weight, while more severe regimens may result in lighter offspring. Careful quantification of caloric balance during pregnancy in chronic exercisers is needed before further conclusions can be drawn. Indeed, the interaction between energy expenditure (whether job related or leisure time) and caloric consumption must be addressed to determine whether physical activity per se may affect birth outcome, or if it is merely a confounder. Future studies should include randomized trials in which women without a history of chronic physical activity are assigned to either an exercise/physical activity or control group.

Adolescent↗
PubMed1997

Effects of physiologic load of pregnancy on left ventricular contractility and remodeling.

Left ventricular (LV) adaptation to the hemodynamic load of pregnancy has been studied with load-sensitive ejection-phase indexes, but the results of these studies are conflicting. The aim of this study was to examine the effects of the hemodynamic load of pregnancy on the contractile state of the left ventricle by using load-adjusted indexes of contractility. Thirty-four healthy women were prospectively studied by serial echo and Doppler examinations at six periods during pregnancy and after delivery. LV volume increased 10.5%, paralleling the change in stroke volume. End-systolic stress, an index of myocardial afterload, decreased 28.8% because of a decrease in end-systolic pressure and an increase in LV thickness/diameter ratio. Despite the increase in preload and the decrease in afterload, ejection phase indexes did not change during or after pregnancy. Although remaining within the normal range, the afterload-adjusted velocity of circumferential fiber shortening, an index of contractility that is relatively insensitive to preload, transiently decreased by 1.75 SDs during gestation, returning to non-pregnant values 2 to 4 weeks postpartum. Thus the increase in hemodynamic load that characterizes normal pregnancy is associated with preservation of global pump function. The transient decrease in contractile state may represent an adaptation phase of the contractile elements of the myocardium to the rapid changes in loading conditions observed during the first trimester of pregnancy.

Adult↗
PubMed1996

Cardiovascular responses to aerobic exercise during pregnancy and postpartum.

The many physiological and hormonal changes occurring during pregnancy have the potential to affect a woman's cardiovascular responses to aerobic exercise. For example, it seems that increased mass and dilation of the left ventricle allow maintenance of wall stress, ensuring adequate pumping function throughout gestation. Also, a woman's cardiac output response to exercise is typically increased during pregnancy, owing to alterations in both heart rate and stroke volume. However, mean arterial pressure response is not usually affected by pregnancy because the increased blood flow to the uteroplacental unit, skin, and kidneys results in a concomitant decrease in systemic vascular resistance. It should be noted that there is no clear agreement on the mechanisms behind hemodynamic responses to exercise throughout gestation. Indeed, a pregnant woman's cardiac output during physical activity may be affected by (1) gestational age, (2) body position, (3) exercise intensity and modality, and (4) fitness level.

Cardiac Output↗
PubMed1996

The reliability of aerobic capacity (VO2max) testing in adolescent girls.

Despite the fact that our subjects were naive regarding the test procedures, it appears that aerobic fitness testing using an incremental treadmill protocol is extremely reliable in adolescent girls. In addition, day-to-day variability of VO2max in our subjects averaged less than 5%, which is similar to results obtained with adults (Katch, Sady, & Freedson, 1982). Finally, it was most encouraging to find that a single VO2max test trial resulted in high reliability coefficients. This finding should provide a great deal of confidence to investigators who are performing aerobic fitness tests on large numbers of subjects where multiple testing is neither practical nor cost-effective.

Adolescent↗
PubMed1996

A randomized, placebo-controlled trial of combined insulin-like growth factor I and low dose growth hormone therapy for wasting associated with human immunodeficiency virus infection.

Loss of body mass, or wasting, is a major cause of morbidity and a contributor to mortality in human immunodeficiency virus-1 (HIV-1) infection. Dietary supplements and appetite adjuvants have had limited effectiveness in treating this condition. GH and insulin-like growth factor I (IGF-I) have been shown to be anabolic in many catabolic conditions, and limited data suggest similar efficacy in HIV wasting. In addition, it appears that GH and IGF-I may have complementary anabolic effects with opposing glucoregulatory effects. We report results from a 12-week randomized, placebo-controlled trial of combination recombinant human GH (rhGH; Nutropin; 0.34 mg, sc, twice daily) and rhIGF-I (5.0 mg, sc, twice daily) in individuals with HIV wasting and without active opportunistic infection, cancer, or gastrointestinal disease. A total of 142 subjects (140 males and 2 females) were randomized using a 2:1, double blind treatment scheme and assigned to receive either active treatment or placebo injections. Eighty subjects completed the 12-week protocol. Nutritional intake and demographic and clinical characteristics did not differ between the groups at any study time point. At 3 weeks, the treatment group had a significantly larger weight increase (P = 0.0003), but this difference was not observed at any later time point. Similarly, fat-free mass, calculated from skinfold measurements, increased transiently in the treatment group at 6 weeks (P = 0.002). No significant differences in isokinetic muscle strength or endurance testing or in quality of life were observed between the groups. Resting heart rate was significantly higher in the treatment group at each time point post-baseline. GH and IGF-binding protein-3 levels did not change; however, IGF-I levels were higher in the treatment group at 6 and 12 weeks. There were no significant between-group differences in any of the measured biochemical or immunological parameters. rhGH plus rhIGF-I treatment was associated with an increased incidence of peripheral edema and other side-effects, possibly related to fluid retention. We conclude that the combination of rhIGF-I and low dose rhGH used in this study had no significant anabolic effect in HIV wasting.

Acquired Immunodeficiency Syndrome↗
PubMed1996

Changes in body composition of human immunodeficiency virus-infected males receiving insulin-like growth factor I and growth hormone.

Weight loss is a common, persistent characteristic of long term human immunodeficiency virus (HIV-1) infection; its full etiology remains unknown. Because treatment with GH has induced nitrogen retention in various catabolic conditions, we designed this study to determine whether a moderate dose of insulin-like growth factor I (IGF-I) combined with a low GH dose could impede the catabolic response seen in HIV-1 infection. A double blind, placebo-controlled study design was used. Subjects in the GH/IGF-I treatment group (n = 44) and control group (n = 22) continued to receive their routine stable antiretroviral therapy. No patient had a recent history of opportunistic infection, malignancy, or Kaposi's sarcoma and had dietary intakes of at least 25 Cal/kg weight.day at study entry. During the 12-week study period, dietary instruction was given, and subjects were encouraged to maintain an intake of 35 Cal/kg and 1 g protein/kg. All subjects had a body mass index of 19.8 kg/m2 or less at the time of study entry or a weight loss of 10% or more of their premorbid weight and a body mass index below 26.1 kg/m2. The treatment group received 0.34 mg (0.68 mg/day) GH, twice daily, and 5.0 mg (10 mg/day) IGF-I, twice daily. Changes in body composition of total body potassium (TBK), total body nitrogen (TBN), fat-free mass (FFM), and body fat (Fat) were examined at 6 and 12 weeks during the treatment period. TBK, TBN, FFM, and Fat for the treatment and placebo groups were, on the average, below normal at study entry. At 6 weeks, the GH/IGF-I group showed a significant increase in FFM (P < 0.0001), a minimal increase in TBK (P < 0.05), and a substantial decrease in Fat (P < 0.01) compared with baseline values. The loss of body fat continued to be significant (P < 0.01) in the GH/IGF-I group treatment at 12 weeks, whereas the increase in FFM was minimal (P < 0.05). No significant changes in the mean body composition occurred at 6 or 12 weeks in the placebo group. By 12 weeks, neither TBK (body cell mass) nor TBN (total protein mass) had significantly increased relative to the values at baseline, although the FFM remained elevated. Thus, the combined GH and IGF-I doses used in this study in adult males with HIV-associated weight loss were ineffective in producing a sustained anabolic response and, in fact, resulted primarily in a significant loss of body fat.

Absorptiometry, Photon↗
PubMed1995

Prediction of maximum voluntary ventilation (MVV) in African-American adolescent girls.

The purposes of the present study were to: 1) develop original equations to predict maximum voluntary ventilation (MVV) in African-American adolescent girls; and 2) determine the validity of existing MVV prediction equations for use in African-American subjects by comparing predicted MVV values in the literature with actual MVV values obtained in this study. Forced expiratory volume in 1 second (FEV1), forced vital capacity (FVC), and 12 second MVV were measured with a clinical respirometer (Spirometrics model 2451) in 93 African-American adolescent girls (13.5 +/- 1.0 years). Age (r = 0.29), height (r = 0.38), FEV1 (r = 0.52), and FVC (r = 0.48) were significantly (P < 0.01) correlated with MVV. Multiple regression analysis was used to develop equations to predict MVV with age, height, and FEV1 as predictor variables. Using Mallow's Cp criterion, age-FEV1 and FEV1 equations appeared to be the most accurate predictors of MVV. When MVV was regressed on FEV1 in a non-intercept model, the result was the commonly cited equation MVV = 35.0 x FEV1. Thus, the previously established relationship between FEV1 and MVV can be extended to African-American adolescent girls. Comparison of predicted MVV values calculated from other published equations with our subjects' actual values indicated that equations using age and/or height as predictors did not accurately predict MVV in our subjects.

Adolescent↗
PubMed1995

Ethnicity affects aerobic fitness in US adolescent girls.

The purpose of this investigation was to determine whether aerobic fitness (VO2max) differed between black (N = 40) and white (N = 53) adolescent girls who were similar in age (13.5 yr) and percent body fat (24.6%). Expired gases were collected continuously while each girl performed a standard Bruce protocol to volitional exhaustion on a motorized treadmill (TM). Heart rates (HR) were measured during the exercise testing via telemetry. Fat-free mass (FFM) was estimated with total body electrical conductivity (TOBEC). Average (+/- SD) maximum HR (black = 194 +/- 7; white = 198 +/- 8) and respiratory exchange ratios (black = 1.17 +/- 0.08; white = 1.22 +/- 0.09) did not differ between subject groups. Aerobic fitness was significantly lower (P < 0.01) lower in black versus white girls when VO2max was expressed relative to body weight (31.8 +/- 5.8 vs 38.5 +/- 6.8 ml.kg(-1).min(-1)) and body weight raised to the 0.67 power (120.9 +/- 19.5 vs 138.5 +/- 20.7 ml.kg(-0.67).min-1). Treadmill time to exhaustion was significantly less (P < 0.01) in the black (8.49 +/- 1.30 min) versus white (9.41 +/- 1.60) subjects. Also, black subjects demonstrated less ability to utilize O2 during maximal exercise at a given FFM. This suggests the black girls' FFM contained a smaller percentage of skeletal muscle mass that could be utilized during treadmill exercise. It is possible that lower aerobic fitness values seen in the black girls are related to a combination of anatomical, physiological and/or behavioral factors.

Adipose Tissue↗