Biomedical subjects

M S Treuth

Publications and source records attributed to M S Treuth.

31 records · Page 2Linked to original sources

PubMed1997

Maximal aerobic capacity in African-American and Caucasian prepubertal children.

The purpose of this study was to examine differences in resting, submaximal, and maximal (VO2max) oxygen consumption (VO2) in African-American (n = 44) and Caucasian (n = 31) prepubertal children aged 5-10 yr. Resting VO2 was measured via indirect calorimetry in the fasted state. Submaximal VO2 and VO2max were determined during an all out, progressive treadmill exercise test appropriate for children. Dual-energy X-ray absorptiometry was used to determine total fat mass (FM), soft lean tissue mass (LTM), and leg soft LTM. Doubly labeled water was used to determine total energy expenditure (TEE) and activity energy expenditure (AEE). A significant effect of ethnicity (P < 0.01) was found for VO2max but not resting or submaximal VO2, with African-American children having absolute VO2max approximately 15% lower than Caucasian children (1.21 +/- 0.032 vs. 1.43 +/- 0.031 l/min, respectively). The lower VO2max persisted in African-American children after adjustment for soft LTM (1.23 +/- 0.025 vs. 1.39 +/- 0.031 l/min; P < 0.01), leg soft LTM (1.20 +/- 0.031 vs. 1.43 +/- 0.042 l/min; P < 0.01), and soft LTM and FM (1.23 +/- 0.025 vs. 1.39 +/- 0.031 l/min; P < 0.01). The lower VO2max persisted also after adjustment for TEE (1.20 +/- 0.02 vs. 1.38 +/- 0.0028 l/min P < 0.001) and AEE (1.20 +/- 0.024 vs. 1.38 +/- 0.028 l/min; P < 0.001). In conclusion, our data indicate that African-American and Caucasian children have similar rates of VO2 at rest and during submaximal exercise, but VO2max is approximately 15% lower in African-American children, independent of soft LTM, FM, leg LTM, TEE, and AEE.

Absorptiometry, Photon↗

PubMed1996

Effects of exercise intensity on 24-h energy expenditure and substrate oxidation.

The purpose of this study was to determine: 1) the reliability of 24-h respiratory calorimetry measurements, and 2) the effects of low- versus high-intensity exercise on energy expenditure (EE) and substrate oxidation over a 24-h period. Eight women (age 28 +/- 4.3 yr) were measured for body composition, maximal oxygen consumption while cycling, and EE in three, 24-h calorimeter tests, with identical work output but differing intensity during a 60-min exercise session. Low-intensity (LI) exercise involved continuous cycling at 50% VO2max; whereas high-intensity (HI) exercise involved interval cycling (2 min exercise/recovery) at 100% VO2max. Subjects were randomly assigned to the first two tests at LI or HI, with the third test at the alternate intensity. No differences in EE or respiratory quotient (RQ) during rest, sleep, exercise, or over the 24 h were found between the first two tests (C.V. = 6.0%), demonstrating the reliability of the measurements. The HI protocol elicited significantly higher EE than LI during rest, exercise, and over 24 h, whereas sleeping EE approached significance. No significant differences in RQ during rest, sleep, or over 24 h were found, but 24-h lipid and carbohydrate oxidation were similar in the two protocols. The HI exercise RQ was significantly higher than LI. These findings demonstrated higher 24-h EE in the HI than LI protocol, but similar 24-h substrate oxidation rates.

Adult↗

PubMed1996

Intra-abdominal adipose tissue, physical activity and cardiovascular risk in pre- and post-menopausal women.

OBJECTIVE: Determine whether the independent inter-relationships between intra-abdominal adipose tissue (IAF) cardiovascular disease (CVD) risk, and physical activity (PA) support the hypothesis that the beneficial effect of PA of CVD risk is mediated through the effects of activity on IAF. DESIGN: Cross-sectional. SUBJECTS: 220 female Caucasian women 17-77 years old. MEASUREMENTS: Computed tomography IAF and subcutaneous abdominal adipose tissue (SAF), percent fat, CVD risk factors (blood lipids and blood pressure) and PA using the Baecke questionnaire. RESULTS: Zero-order correlations indicated that IAF, SAF, percent fat, age, menopausal status (MS), and all 4 of the PA indexes were consistently related to CVD risk. After adjusting for age, MS, SAF, and percent fat, IAF was negatively related to PA (r2 = 0.04), indicating that more active women had relatively small IAF compared to other fat depots. After adjusting for IAF, MS, and age none of the PA indexes were related to any of the CVD risk factors except cholesterol/HDL ratio (partial r2 = 0.02). However, after adjusting for PA, MS and age, IAF was related to all CVD risk factors except cholesterol (partial r2 = 0.03-0.23). CONCLUSION: These results support the hypothesis that PA may obtain at least part of its effect on CVD risk by reducing IAF.

Abdomen↗

PubMed1995

Obesity in children: recent advances in energy metabolism and body composition.

In this paper we review recent advances in energy metabolism and body composition studies in prepubescent children and the relationship to childhood obesity. Our review on energy expenditure focusses on studies of total energy expenditure using doubly labeled water, the role of energy expenditure in the development of obesity, and the determinants of resting energy expenditure in children. The relatively few studies that have examined the regulation of energy and macronutrient intake in children are also reviewed. In terms of body composition, we focus on recent methodological studies that have developed existing techniques for application to the pediatric population, including dual energy X-ray absorptiometry and bioelectrical resistance. Lastly, we review existing information relating to measurement and alteration of body fat distribution in children.

Body Composition↗

PubMed1995

Effects of strength training on muscle hypertrophy and muscle cell disruption in older men.

To determine whether a total body, heavy resistance, strength training (ST) program can significantly increase muscle strength and hypertrophy without muscle cell disruption and soreness in older men, 35 sedentary male subjects between the ages of 50 and 69 years of age (60 +/- 5, mean +/- SD) were studied. Twelve served as inactive controls. Muscular strength, cross-sectional muscle area, serum creatine kinase (CK) activity and perceived soreness were assessed before and after a 16 wk heavy resistance ST program. The ST program resulted in a 43% increase in muscular strength (p < 0.001), and a 7.2% increase in midthigh muscle area (153 +/- 24 vs 164 +/- 23 cm2, p < 0.001). There were no significant changes in strength or muscle area in the inactive control group. Peak serum CK levels were approximately twofold above baseline (278 +/- 175 vs 133 +/- 88 U/l, p < 0.01) 8 h after the first regular training session. At the end of training, the peak rise in CK levels was also reached 8 h after exercise, but was reduced substantially at the same absolute (p < 0.01) and relative resistance loads (p < 0.01) compared to the first training session. Muscle soreness after exercise was only occasionally reported at the beginning of training and was almost nonexistent after training. These results indicate that middle-aged and older men can safely participate in a total body strength training program, intense enough to produce substantial increases in muscle strength and hypertrophy, without promoting muscle soreness or significant muscle cell disruption.(ABSTRACT TRUNCATED AT 250 WORDS)

Adipose Tissue↗

PubMed1995

Estimating intraabdominal adipose tissue in women by dual-energy X-ray absorptiometry.

The purposes of this study were 1) to derive a prediction equation for estimating the intraabdominal adipose tissue (IAAT) by using dual-energy X-ray absorptiometry (DXA) with computed tomography (CT) scans as the criterion method, 2) to examine whether a smaller, more specific region was a better estimator of IAAT than the trunk alone by drawing three regions of interest (upper trunk, lower trunk, and pelvis) in the DXA scan, and 3) to cross-validate the newly developed equations and earlier equations by Svendsen. Body composition was measured in 206 pre- and postmenopausal women by anthropometry, DXA, and CT. Subjects were randomly divided into estimation (n = 151) and validation (n = 55) samples. Body-composition variables were analyzed by stepwise multiple regression to determine equations to estimate IAAT. The two equations developed to estimate IAAT both yielded an R2 of 0.81 when using the following variables: 1) sagittal diameter, age, waist circumference, and DXA trunk percent fat, and 2) sagittal diameter, age, waist circumference, and DXA pelvic percent fat. The R2 between the actual IAAT and estimates of IAAT for both equations was 0.81, whereas the R2 values were 0.63 and 0.71 for the Svendsen equations. In conclusion, we developed new equations using DXA and other simple measures that can be used to estimate IAAT in women of varying ages and body compositions.

Abdomen↗

PubMed1995

The effects of strength conditioning on older women's ability to perform daily tasks.

OBJECTIVES: The objectives of this study were to determine the effects of a strength-training program on walking speed and relative muscular stress, as measured by normalized integrated electromyographic (nIEMG) activity, while carrying a box of groceries and standing from a chair. DESIGN: Prospective intervention study. SETTING: Volunteer subjects from the community of Birmingham, Alabama. PARTICIPANTS: Fourteen healthy women aged 60 to 77 years. INTERVENTION: Sixteen weeks of total body strength conditioning. MEASUREMENTS: Before and after 16 weeks of strength conditioning, the following variables were evaluated for all subjects: (1) strength, six isotonic tests and two isometric tests; (2) walking velocity; (3) nIEMG of the biceps while carrying a box of groceries; and (4) nIEMG of the rectus femoris while standing from a chair. MAIN RESULTS: After the strength training program, subjects' isotonic strength increased significantly, an average of 52% on the isotonic tests and 31% on the isometric tests. Walking velocity also increased significantly (18%). nIEMG of the biceps decreased 36% while carrying a box of groceries. Rectus femoris nIEMG decreased 40% while standing and 47% while sitting. CONCLUSIONS: After strength conditioning, healthy older women showed not only substantially increased strength but also improvements in walking velocity and the ability to carry out daily tasks such as rising from a chair and carrying a box of groceries.

Activities of Daily Living↗

PubMed1995

Reduction in intra-abdominal adipose tissue after strength training in older women.

The purpose of this study was to examine the effects of a total body strength-training program on changes in total and regional body composition, in particular intra-abdominal adipose tissue (IAAT), in older women. Fourteen healthy older women (mean age 67 +/- 1 yr) exercised 3 times/wk for 16 wk. Strength was assessed by one-repetition maximum tests, with training intensity gradually increased to approximately 67% of one repetition maximum. Body composition was measured by hydrodensitometry and regional body composition was measured by computed tomography. Strength was significantly increased in the upper (51%) and lower body (65%). There was no significant change in body weight (64.4 +/- 2.7 vs. 64.2 +/- 2.7 kg), total body fat (38.7 +/- 1.4 vs. 38.0 +/- 1.6%) or fat-free mass (39.7 +/- 1.0 vs. 40.0 +/- 0.9 kg). However, after ST, there were significant reductions in IAAT (143.9 +/- 13.3 vs. 130.0 +/- 12.4 cm2), the IAAT-to-subcutaneous adipose tissue ratio (0.48 +/- 0.04 vs. 0.44 +/- 0.04), and midthigh subcutaneous adipose tissue (141.7 +/- 11.5 vs. 133.6 +/- 10.8 cm2) and an increase in midthigh muscle (52.9 +/- 2.6 vs. 58.0 +/- 2.0 cm2) (all P < 0.05). In conclusion, significant reductions in IAAT and an increase in strength and muscle area were observed after a strength-training program in healthy older women. These changes may be important in preventing the negative health outcomes associated with the age-related increase in intra-abdominal obesity.

Abdomen↗

PubMed1995

Energy expenditure and substrate utilization in older women after strength training: 24-h calorimeter results.

The purpose of this study was to examine the effects of strength training (ST) in healthy older women on 24-h energy expenditure (EE) and its components and on 24-h substrate utilization. Thirteen women (age 67 +/- 1 yr) exercised three times per week for 16 wk in a total body ST program. EE components and substrate utilization were determined for 24 h in an indirect room calorimeter before and after training. The ST invoked a 47% increase in upper body and a 66% increase in lower body strength (P < 0.001). Body weight, percent body fat, and fat-free mass did not change significantly; however, midthigh muscle area increased (55.2 +/- 3.1 vs. 60.4 +/- 2.3 cm2; P < 0.05). There are a significant increase in resting EE (5,017 +/- 218 vs. 5,473 +/- 213 kJ/day; P < 0.05) but no significant changes in sleeping EE (4,929 +/- 180 vs. 5,067 +/- 251 kJ/day), diet-induced thermogenesis (359 +/- 25 vs. 393 +/- 33 kJ/day), activity EE (682 +/- 84 vs. 381 +/- 117 kJ/day), or 24-h EE (6,054 +/- 188 vs. 6,247 +/- 243 kJ/day). The increase in resting EE was not significant after the increase in muscle area is taken into account. The 24-h nonprotein respiratory quotient decreased (0.90 +/- 0.01 vs. 0.82 +/- 0.01; P < 0.001), revealing a significant increase in 24-h fat oxidation (42 +/- 6 vs. 81 +/- 7 g/day) and a decrease in carbohydrate oxidation (180 +/- 14 vs. 113 +/- 10 g/day; both P < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗

PubMed1994

Effects of strength training on total and regional body composition in older men.

The effects of a 16-wk strength-training program on total and regional body composition were assessed by dual-energy X-ray absorptiometry (DEXA), magnetic resonance imaging (MRI), and hydrodensitometry in 13 untrained healthy men [60 +/- 4 (SD) yr]. Nine additional men (62 +/- 6 yr) served as inactive controls. The strength-training program resulted in substantial increases in both upper (39 +/- 8%; P < 0.001) and lower (42 +/- 14%; P < 0.001) body strength. Total fat-free mass (FFM) increased by 2 kg (62.0 +/- 7.1 to 64.0 +/- 7.2 kg; P < 0.001), and total fat mass decreased by the same amount (23.8 +/- 6.7 to 21.8 +/- 6.0 kg; P < 0.001) when measured by DEXA. When measured by hydrodensitometry, similar increases in FFM (61.3 +/- 7.8 to 63.0 +/- 7.6 kg; P < 0.01) and decreases in fat mass (23.8 +/- 7.9 to 22.1 +/- 7.7 kg; P < 0.001) were observed. When measured by DEXA, FFM was increased in the arms (6.045 +/- 0.860 to 6.418 +/- 0.803 kg; P < 0.01), legs (19.416 +/- 2.228 to 20.131 +/- 2.303 kg; P < 0.001), and trunk (29.229 +/- 4.108 to 30.134 +/- 4.184 kg; P < 0.01), whereas fat mass was reduced in the arms (2.383 +/- 0.830 to 2.128 +/- 0.714 kg; P < 0.01), legs (7.583 +/- 1.675 to 6.945 +/- 1.551 kg; P < 0.001), and trunk (12.216 +/- 4.143 to 11.281 +/- 3.653 kg; P < 0.01) as a result of training.(ABSTRACT TRUNCATED AT 250 WORDS)

Absorptiometry, Photon↗

PubMed1994

Strength training increases insulin action in healthy 50- to 65-yr-old men.

The insulin resistance associated with aging may be due, in part, to reduced levels of physical activity in the elderly. We hypothesized that strength training increases insulin action in older individuals. To test this hypothesis, 11 healthy men 50-63 yr old [mean 58 +/- 1 (SE) yr] underwent a two-step hyperinsulinemic-euglycemic glucose clamp with concurrent indirect calorimetry and an oral glucose tolerance test (OGTT) before and after 16 wk of strength training. The training program increased overall strength by 47% (P < 0.001). Fat-free mass (FFM; measured by hydrodensitometry) increased (62.4 +/- 2.1 vs. 63.6 +/- 2.1 kg; P < 0.05) and body fat decreased (27.2 +/- 1.8 vs. 25.6 +/- 1.9%; P < 0.001) with training. Fasting plasma glucose levels and glucose levels during the OGTT were not significantly lower after training. In contrast, fasting plasma insulin levels decreased (85 +/- 25 vs. 55 +/- 10 pmol/l; P < 0.05) and insulin levels decreased (P < 0.05, analysis of variance) during the OGTT. Glucose infusion rates during the hyperinsulinemic-euglycemic glucose clamp increased 24% (13.5 +/- 1.7 vs. 16.7 +/- 2.2 mumol.kg FFM-1.min-1; P < 0.05) during the low (20 mU.m-2.min-1) insulin infusion and increased 22% (55.7 +/- 3.3 vs. 67.7 +/- 3.9 mumol.kg FFM-1.min-1; P < 0.05) during the high (100 mU.m-2.min-1) insulin infusion. These increases were accompanied by a 40% increase (n = 7; P < 0.08) in nonoxidative glucose metabolism during the high insulin infusion. These results demonstrate that strength training increases insulin action and lowers plasma insulin levels in middle-aged and older men.

Aged↗

PubMed1994

Effects of strength training on bone mineral density: hormonal and bone turnover relationships.

The effects of a 16-wk strength-training program on bone mineral density (BMD) was assessed by dual-energy X-ray absorptiometry in 21 men [age 61 +/- 1 (SE) yr]. Sixteen men (age 59 +/- 2 yr) served as control subjects. To investigate the possible hormonal relationships underlying the effects on BMD, serum concentrations of growth hormone, insulin-like growth factor I, and testosterone were determined before and after training. In addition, osteocalcin and skeletal alkaline phosphatase (markers of bone formation) and tartrate-resistant acid phosphatase (a marker of bone resorption) were measured before and after training to assess bone turnover. The training program resulted in a 2.8 +/- 0.6% increase in femoral neck BMD (1.004 +/- 0.037 vs. 1.031 +/- 0.037 g/cm2; P < 0.001). However, there were no significant changes in total body, anterioposterior spine, lateral spine, Ward's triangle, or greater trochanter BMD. Moreover, there were no significant changes in growth hormone, insulin-like growth factor I, testosterone, osteocalcin, or skeletal alkaline phosphatase. There were no changes in the control group. Thus, strength training can increase femoral neck BMD, and this effect does not appear to be accompanied by changes in anabolic hormones or markers of bone formation and resorption.

Absorptiometry, Photon↗

PubMedDate not supplied

Effects of strength training on cardiovascular responses during a submaximal walk and a weight-loaded walking test in older females.

PURPOSE: The purpose of this study was to examine the effects of a total body strength training program on oxygen uptake (VO2), heart rate (HR), systolic blood pressure (SBP), and rate pressure product (RPP) during a submaximal walk and a weight-loaded walking test in healthy women 60-77 years old. METHODS: The submaximal walk (2 mph and 3.5% grade) took place during stage 3 of a graded exercise test. The weight-loaded walking task consisted of treadmill walking at 2 mph while carrying a box weighing 40% of maximum isometric elbow flexion strength. The women strength trained three times per week for approximately 1 hour per session for 16 weeks. RESULTS: Paired t tests determined that strength increased by 57% on six isotonic strength tests (one repetition maximum) and by 29% on two isometric strength tests. A repeated measures analysis of variance (ANOVA) was used to determine the pre- to post-differences between and within the two tests (alpha = 0.05). There was no change in VO2 but HR, SBP, and RPP decreased significantly during the submaximal walk and the weight-loaded walking test. However, average HR (135 to 120 bpm) and RPP (23.3 x 10(3) to 19.3 x 10(3)) decreased more during the weight-loaded walking test than during the submaximal walk (HR: 108 to 104 bpm; RPP 18.3 x 10(3) to 17.0 x 10(3)). CONCLUSIONS: In conclusion, the reduced HR, SBP, and RPP indicates that strength training may reduce cardiovascular stress during daily tasks in healthy older women.

Age Factors↗