Associations Between Body Composition and Performance in Elite Endurance Athletes.

Physical activity interventions alone often do not elicit favorable changes in body composition. However, most studies have reported only mean changes in body composition across treatment groups. PURPOSE: To examine the extent to which individual-level energy expended (EE) during an exercise program is associated with changes in body mass and composition. METHODS: The sample included 666 adult participants (43% men, 32% black) from the HERITAGE Family Study. The training involved a progressive (55-75% VO2max) 20-week cycling program. The power output and duration of each training session was recorded, and the EE (kcal) was calculated for each individual. Body weight, BMI, waist and hip circumference, fat mass (FM), fat free mass (FFM), percent body fat (%BF), CT-derived visceral adipose tissue (VAT) and subcutaneous tissue (SAT) were measured pre- and post-training. Stepwise regression models were used to determine associations between absolute changes (post-pre) in body composition from EE, age, race and baseline values. RESULTS: For the total sample, EE (mean ± SD) was 18,509 ± 6,966 kcal with -0.3 ± 2.5 kg weight loss. On average, men expended more than women (23,664 ± 6,652 vs. 14,607 ± 4,056 kcal; p<0.001) and whites expended more than blacks (20,200 ± 7,126 vs. 14,938 ± 5,008 kcal; p<0.001). For the total sample, changes in FM (p<0.01) and %BF (p<0.01) were negatively associated with EE. In women, EE was positively associated with changes in FFM (p<0.02). For men, EE was negatively associated with changes in weight (p<0.01), BMI (p<0.01), FM (p<0.03), and FFM (p<0.01). Overall, the variance in changes in body composition explained by EE was low (partial r2 = 0.5-2.3%). CONCLUSIONS: The average weight loss in this study was nominal and individual level energy expended was weakly associated with changes in body composition, particularly in men.

Because of the improved survival rate, both short term and long term adverse effects of breast cancer treatment have become increasingly important. Body weight and body composition before, during, and after chemotherapy may influence side effects during treatment and survival. The aims of this thesis were to assess among stage I-IIIB breast cancer patients: 1) the association between pre-treatment body composition and dose-limiting toxicities during chemotherapy, 2) potential changes in body weight and body composition during and after chemotherapy compared to changes in age-matched women without cancer in the same time period, and 3) dietary intake during chemotherapy compared to age-matched women without cancer in the same time period. Chapter 2 describes the association between pre-treatment body composition and dose-limiting toxicities during chemotherapy. Data from 172 breast cancer patients who participated in the COBRA-study were analysed. Body composition was measured using a total body Dual Energy X-ray Absorption (DEXA) scan. Information regarding dose-limiting toxicities was abstracted from medical records. A higher BMI (kg/m2) and a higher fat mass (kg and percentage) were associated with an increased risk of dose-limiting toxicity, while lean body mass (kg) was not associated with risk of toxicities. Chapter 3 presents the findings of a meta-analysis on changes in body weight during chemotherapy in breast cancer patients. The meta-analysis showed an overall gain in body weight of 2.7 kg (95% CI: 2.0-3.3) during chemotherapy, with a high degree of heterogeneity (I2= 94.2%). Weight gain in breast cancer patients was more pronounced in papers published before 2000 and studies including cyclophosphamide, methotrexate and 5-fluorouracil as chemotherapy regime. Chapter 4 describes changes in body weight and body composition during and after chemotherapy. Data from 145 patients and 121 women of an age-matched comparison group, participating in the COBRA-study were analysed. Body composition was measured using DEXA-scan at three time points during the study period. For the patient group, these tie points were: before start of chemotherapy, shortly after chemotherapy, and 6 months after chemotherapy. For the comparison group these measurements were conducted over a similar time frame: baseline, 6 months after baseline, and 12 months after baseline. In addition, we identified determinants of changes in body weight and body composition. Shortly after chemotherapy, patients had a significantly higher body weight, BMI, and lean body mass than women in the comparison group, while fat mass was similar. Six months after chemotherapy no differences in body weight or body composition were observed between the patient and comparison group. A younger age, better appetite during chemotherapy, and an ER-receptor negative tumour were associated with greater changes in body weight over time. A younger age and better appetite during chemotherapy were associated with greater changes in fat mass over time, while the only determinant associated with greater changes in lean body mass over time was a better appetite during chemotherapy. Chapter 5 describes the dietary intake and food groups before and during chemotherapy of breast cancer patients compared with women without cancer. In addition we assessed the association between symptoms and energy intake. Data from 117 breast cancer patients and 88 women without breast cancer who participated in the COBRA-study were used. Habitual dietary intake before chemotherapy was assessed using a food frequency questionnaire. Two 24-hr dietary recalls were used to assess actual dietary intake during chemotherapy for patients and within 6 months for the comparison group. Shortly after the 24-hr dietary recall, participants filled out questionnaires about symptoms. Before chemotherapy, dietary intake was similar for both groups. During chemotherapy, breast cancer patients reported significantly lower total energy, total fat, total protein, and alcohol intake than women without cancer, which could be explained by a lower intake of specific food groups. Overall results from this thesis suggest that pre-treatment fat mass is associated with dose-limiting toxicities during chemotherapy. Weight gain during chemotherapy appeared to be more modest than we expected based on literature and changes in body composition during chemotherapy consist mainly of an increase in lean body mass, which is only temporary and returned to baseline within 6 months after chemotherapy. A higher appetite during chemotherapy was associated with changes in body weight and body composition. A younger age at diagnosis was associated with greater changes in body weight and fat mass, but not with changes in lean body mass. In addition, an ER-receptor negative tumour was associated with greater changes in body weight, but not with changes in fat mass or lean body mass. During chemotherapy women with breast cancer have a lower intake of energy, fat, protein and alcohol compared to age-matched women without cancer, which was expressed in a lower intake of specific food groups. The results of this thesis do not suggest that dietary intake is associated with weight gain during chemotherapy.

Changes in body composition in women using long-acting reversible contraception

Both baseline cardiorespiratory fitness and adiposity predict the risk of cancer mortality. However, the effects of changes in these two factors over time have not been evaluated thoroughly. The aim of this study was to examine the independent and joint associations of changes in cardiorespiratory fitness and body composition on cancer mortality. The cohort consisted of 13,930 men (initially cancer-free) with two or more medical examinations from 1974 to 2002. Cardiorespiratory fitness was assessed by a maximal treadmill exercise test, and body composition was expressed by body mass index (BMI) and percent body fat. Changes in cardiorespiratory fitness and body composition between the baseline and the last examination were classified into loss, stable, and gain groups. There were 386 deaths from cancer during an average of 12.5 yr of follow-up. After adjusting for possible confounders and BMI, change hazard ratios (95% confidence intervals) of cancer mortality were 0.74 (0.57-0.96) for stable fitness and 0.74 (0.56-0.98) for fitness gain. Inverse dose-response relationships were observed between changes in maximal METs and cancer mortality (P for linear trend = 0.05). Neither BMI change nor percent body fat change was associated with cancer mortality after adjusting for possible confounders and maximal METs change. In the joint analyses, men who became less fit had a higher risk of cancer mortality (P for linear trend = 0.03) compared with those who became more fit, regardless of BMI change levels. Being unfit or losing cardiorespiratory fitness over time was found to predict cancer mortality in men. Improving or maintaining adequate levels of cardiorespiratory fitness appears to be important for decreasing cancer mortality in men.

Obesity and sarcopenia are health problems associated with ageing. The present study modelled the longitudinal changes in body composition of healthy men, aged from 20 to 96 years, and evaluated the fidelity of BMI to identify age-dependent changes in fat mass and fat-free mass. The data from 7265 men with multiple body composition determinations (total observations 38,328) were used to model the age-related changes in body mass, fat mass, fat-free mass, BMI and percentage of body fat. Changes in fat mass and fat-free mass were used to evaluate the fidelity of BMI and to detect body composition changes with ageing. Linear mixed regression models showed that all trajectories of body composition with healthy ageing were quadratic. Fat mass, BMI and percentage of body fat increased from age 20 years and levelled off at approximately 80 years. Fat-free mass increased slightly from age 20 to 47 years and then declined at a non-linear rate with ageing. Levels of aerobic exercise had a positive influence on fat mass and a slight negative effect on fat-free mass. BMI and percentage of body fat were sensitive in detecting the increase in fat mass that occurred with healthy ageing, but failed to identify the loss of fat-free mass that started at age 47 years.

Comparison of methods for assessing body-composition changes over 1 y in postmenopausal women

We determined the effects of conjugated linoleic acid (CLA) supplementation during resistance training. Seventy-six subjects were randomized to receive CLA (5 g.d(-1)) or placebo (PLA) for 7 wk while resistance training 3 d.wk(-1). Seventeen subjects crossed over to the opposite group for an additional 7 wk. Measurements at baseline, 7 wk, and 14 wk (for subjects in the crossover study) included body composition, muscle thickness of the elbow flexors and knee extensors, resting metabolic rate (RMR), bench and leg press strength, knee extension torque, and urinary markers of myofibrillar degradation (3-methylhistidine (3MH) and bone resorption (cross-linked N-telopeptides (Ntx)). After 7 wk the CLA group had greater increases in lean tissue mass (LTM) (+1.4 vs +0.2 kg; P < 0.05), greater losses of fat mass (-0.8 vs +0.4 kg; P < 0.05), and a smaller increase in 3MH (-0.1 vs + 1.3 micromol.kg LTM.d(-1); P < 0.05) compared with PLA. Changes between groups were similar for all other measurements, except for a greater increase in bench press strength for males on CLA (P < 0.05). In the crossover study subjects had minimal changes in body composition, but smaller increases in 3MH (-1.2 vs +2.2 micromol.kg LTM.d(-1); P < 0.01) and NTx (-4.8 vs +7.3 nmol.kg(-1) LTM.d(-1); P < 0.01) while on CLA versus PLA. Supplementation with CLA during resistance training results in relatively small changes in body composition accompanied by a lessening of the catabolic effect of training on muscle protein.

Tracking changes in body composition (BC) is critical for observational and intervention studies. Little is known about the best approaches to tracking BC changes. PURPOSE: To compare air plethysmography (AP) and bioelectrical impedance (BI) estimates of BC in a group of college students, some who lose and some who gain body mass (BM). METHODS: 66 college students (26 males, 40 females, 18.1 y) were measured at the beginning and end of their first year at college. AP and BI were used to estimate fat mass (FM), fat-free mass (FFM), and body fat percentage (%BF). BI also assessed kg of trunk fat. BM, body mass index (BMI), and waist circumference (WC) were measured using standard procedures. Repeated measures ANOVA determined whether AP and BI yielded similar results. Bivariate correlation and multiple regression determined which variables were related to changes in BM, BMI and WC. RESULTS: There was wide variation in BC change, but the majority of individuals gained in BM, WC, and FM. On average, subjects gained 1.6±2.9 kg in BM, 1.24±3.02 cm in WC, and 0.35±1.03 kg/m2 in BMI. %BF increased by 0.64±3.42 and 1.37±2.76% according to AP and BI, respectively. AP yielded higher estimates of %BF than BI (24.0 ± 10.5% vs. 22.8 ± 8.6%, p=0.029). The change in FM estimated from AP was highly and significantly (p<0.01) related to change in BM (r=0.81), BMI (r=0.77), and WC (r=0.61). Change in FM estimated from AP was a stronger predictor of change in WC, BMI, and BM than the AP-derived change in FFM or %BF or any of the variables estimated by BI. CONCLUSION: AP and BI both reflect an increase in FM over time in college students. However, differences in estimates from the 2 methods do not allow them to be used interchangeably. The changes in FM according to AP are most reflective of the changes in BM, BMI, and WC.

Editor's evaluation: The effects of caloric restriction on adipose tissue and metabolic health are sex- and age-dependent

Prolonged longevity in naked mole-rats: age-related changes in metabolism, body composition and gastrointestinal function

1001 Obesity is a significant and widespread dilemma in the United States. Individuals that successfully overcome obesity often struggle to maintain weight loss. PURPOSE: To examine the long-term sustainability of changes in body mass, body composition, and blood profile in previously overweight and obese subjects who participated in a low-calorie diet and exercise program. METHODS: Twenty-two subjects participated in a 10-week weight loss intervention program followed by a nine-month weight loss maintenance program. A 1200-calorie diet was used during intervention. Daily physical activity was recorded via pedometers. Throughout maintenance, total caloric intake was increased to 12 times body weight (in pounds) while daily exercise was continued. Body mass and body composition were measured prior to the 10-week intervention (pretest), prior to the maintenance program (midtest), and following the maintenance program (posttest). Blood profiles were measured in 20 of the 22 subjects. Data were analyzed by repeated measures ANOVA with significance set at p < 0.05. RESULTS: Body mass (−6.3 kg), body mass index (−2.3), percent body fat (−3.0%), fat mass (−4.8 kg), hip circumference (−5.1 cm), and sagittal diameter (−3.6 cm) were reduced significantly during the 10-week weight loss intervention. There were also significant reductions in total cholesterol (−32.6 mg/dl), low-density lipoprotein cholesterol (−20.2 mg/dl), and blood glucose (−8.8 mg/dl) as a result of intervention. There were small, yet non-significant, changes in body mass (+2.5 kg), body mass index (+0.7), percent body fat (−1.2%), fat mass (+0.4 kg), and hip circumference (+0.8 cm) during the nine-month maintenance phase. Similarly, total cholesterol (+15.1 mg/dl), LDL-C (+13.2 mg/dl), and glucose (+4.2 mg/dl) did not significantly change during maintenance. Lean body mass did not change during intervention and maintenance. CONCLUSION: Nine-months following intervention, reductions in body mass, body composition, and blood profile measures can be maintained.

The independent and combined effects of 16 weeks of vigorous exercise and energy restriction on body mass and composition in free-living overweight men—A randomized controlled trial

The aim of the study was to elucidate the effect of weight training with regulated blood flow in the limbs on changes in active and non-active body mass parameters in mixed martial arts fighters. The research sample consisted of 12 male mixed martial arts fighters aged 18.91  2.35 divided into experimental and control groups. Participants performed 2 weight training sessions without (control group) and with regulated blood flow in the limbs (experimental group) per week for 8 weeks. Body composition was measured by InBody 720 with a focus on skeletal muscle mass, body cell mass, body fat mass and percentage of body fat. Due to weight training with regulated blood flow in the limbs was observed statistically significant increase in skeletal muscle mass (p=0.046, r=0.813) and body cell mass BCM (p=0.046, r=0.813). Contrary to weight training without regulated blood flow in the limbs was observed statistically significant decrease in body fat mass (p=0.115, r=0.644) and percentage of body fat (p=0.116, r=0.642). Weight training with regulated blood flow in the limbs at low load intensity can enhance the level of skeletal muscle mass and body cell mass in mixed martial arts fighters, even without muscle failure. In relation to optimalization of non-active body mass parameters it appears to be insufficient.

ObjectiveOur primary objective was to determine the long-term effects of physical activity (PA) and weight loss (WL) on body composition in overweight/obese older adults. Secondarily, we evaluated the association between change in body mass and composition on change in several cardiometabolic risk factors and mobility.Design and Methods288 older (X±SD: 67.0±4.8 years), overweight/obese (BMI 32.8±3.8 kg/m2) men and women participated in this 18 month randomized, controlled trial. Treatment groups included PA+WL (n=98), PA-only (n=97), and a successful aging (SA) health education control (n=93). DXA-acquired body composition measures (total body fat and lean mass), conventional biomarkers of cardiometabolic risk, and 400-m walk time were obtained at baseline and 18 months.ResultsFat mass was significantly reduced from (X±SE) 36.5±8.9 kg to 31.7±9.0 kg in the PA+WL group (p<0.01), but remained unchanged from baseline in the PA-only (−0.8±3.8 kg) and SA (−0.0±3.9 kg) groups. Lean mass losses were three times greater in the PA+WL group compared to PA-only or SA groups (−2.5±2.8 kg vs. −0.7±2.2 kg or −0.8±2.4 kg, respectively; p<0.01); yet due to a larger decrease in fat mass, percent lean mass was significantly increased over baseline in the PA+WL group (2.1%±2.6%; p<0.01). Fat mass loss was primarily responsible for WL-associated improvements in cardiometabolic risk factors, while reduction in body weight, regardless of compartment, was significantly associated with improved mobility.ConclusionThis 18 month PA+WL program resulted in a significant reduction in percent body fat with a concomitant increase in percent body lean mass. Shifts in body weight and composition were associated with favorable changes in clinical parameters of cardiometabolic risk and mobility. Moderate PA without WL had no effect on body composition.

Calorie restriction can inhibit or delay carcinogenesis, reportedly due to a reduction in calorie intake rather than by concurrent changes in body mass and/or composition. Our objective was to test the hypothesis that body mass and/or composition have an important effect, independent of energy intake, on the benefits or hazards associated with calorie restriction or overeating, respectively. In the first experiment, transgenic mice that spontaneously develop prostate cancer [transgenic adenocarcinoma of mouse prostate (TRAMP)] were housed at 27 degrees C or 22 degrees C and pair fed the same diet for 21 weeks (95% of ad libitum intake at 27 degrees C). In the second experiment, TRAMP mice were housed at 27 degrees C or 22 degrees C and fed the same diet ad libitum for 21 weeks. Despite a similar calorie intake, pair-fed mice at 27 degrees C (PF27) were heavier (28.3 +/- 3.3 versus 17.6 +/- 1.6 g at 21 weeks; P < 0.001; mean +/- SD) and had greater fat (6.4 +/- 2.1 versus 1.9 +/- 0.3 g; P < 0.001) and lean mass (P < 0.001) than pair-fed mice at 22 degrees C. Furthermore, PF27 mice had greater levels of serum leptin (P < 0.001), lower levels of adiponectin (P < 0.05), and a greater frequency of prostatic adenocarcinoma (P < 0.05). In contrast, ad libitum-fed mice housed at 22 degrees C consumed approximately 30% more calories than ad libitum-fed mice at 27 degrees C, but there was no difference between groups in body composition or cancer progression. These results imply that the ability of calorie restriction to inhibit or delay cancer incidence and progression is mediated in part by changes in energy balance, body mass, and/or body composition rather than calorie intake per se, suggesting that excess calorie retention, rather than consumption, confers cancer risk.