The authors used 3-component (3C) Db-mineral-model (Lohman, 1986) reference measures to cross-validate Siri’s (1961) 2-component (2C) conversion formula and dual-energy X-ray absorptiometry (DXA) estimates of relative body fat (%BF) for physically active adults. Participants varied in age (18 to 59 y), body fatness, ethnicity (black, Hispanic, white), and physical activity level. The 3C Db-mineral model was used to obtain reference measures of %BF (%BF3C) for comparison with body-composition measures from DXA and hydrodensitometry. For men (n = 110) and women (n = 110), %BF3C (14.0% BF and 24.4% BF, respectively) was more accurately estimated by Siri’s 2C formula (%BFSiri; men, r = 0.97, SEE = 1.77% BF; women, r = 0.98, SEE = 1.56% BF) than by DXA (%BFDXA; men, r = 0.86, SEE = 3.54% BF; women, r = 0.88, SEE = 3.73% BF). The average %BFSiri (men, 15.8% BF; women, 24.7% BF) and %BFDXA (men, 16.2% BF; women, 26.0% BF) differed significantly (P < 0.001) from %BF3C. Siri’s 2C model estimated the average %BF3C in this sample more accurately than DXA did.
Ann L. Gibson, Vivian H. Heyward, Christine M. Mermier, Jeffrey M. Janot and M. Virginia Wilmerding
Johann C. Bilsborough, Thomas Kempton, Kate Greenway, Justin Cordy and Aaron J. Coutts
To compare development and variations in body composition of early-, mid-, and late-career professional Australian Football (AF) players over 3 successive seasons.
Regional and total-body composition (body mass [BM], fat mass [FM], fat-free soft-tissue mass [FFSTM], and bone mineral content [BMC]) were assessed 4 times, at the same time of each season—start preseason (SP), end preseason (EP), midseason (MS), and end season (ES)—from 22 professional AF players using pencil-beam dual-energy X-ray absorptiometry. Nutritional intake for each player was evaluated concomitantly using 3-d food diaries. Players were classified according to their age at the beginning of the observational period as either early- (<21 y, n = 8), mid- (21 to 25 y, n = 9), or late- (>25 y, n = 5) career athletes.
Early-career players had lower FFSTM, BMC, and BM than mid- and late-career throughout. FM and %FM had greatest variability, particularly in the early-career players. FM reduced and FFSTM increased from SP to EP, while FM and FFSTM decreased from EP to MS. FM increased and FFSTM decreased from MS to ES, while FM and FFSTM increased during the off-season.
Early-career players may benefit from greater emphasis on specific nutrition and resistance-training strategies aimed at increasing FFSTM, while all players should balance training and diet toward the end of season to minimize increases in FM.
Stacy D. Hunter, Mandeep S. Dhindsa, Emily Cunningham, Takashi Tarumi, Mohammed Alkatan, Nantinee Nualnim and Hirofumi Tanaka
Obesity is associated with arterial stiffening and diminished quality of life. Bikram yoga may be a feasible alternative to traditional exercise among obese individuals. Accordingly, the purpose of this study was to investigate the impact of Bikram yoga, a heated style of hatha yoga, on arterial stiffness in normal and overweight/obese adults.
Forty-three (23 normal body mass index or BMI; 20 overweight/obese) apparently healthy participants completed an 8-week Bikram yoga intervention. Body composition was estimated via dual energy x-ray absorptiometry, arterial stiffness was measured via brachialankle pulse wave velocity, and health-related quality of life was assessed via RAND 36-Item Short Form survey at baseline and at the end of the 8-week intervention.
After the intervention, brachial-ankle pulse wave velocity decreased (P < .05) in overweight/obese participants while no such changes were observed in normal BMI participants. In the quality of life measures, emotional well-being improved (P < .05) in both groups, and general health improved (P < .05) only in the normal weight BMI group.
Bikram yoga ameliorates arterial stiffness in overweight/obese adults and can positively impact quality of life regardless of BMI.
Ana Anton-Solanas, Barry V. O’Neill, Tessa E. Morris and Joe Dunbar
To assess changes in body composition and monitor cognitive function, subjective well-being, and physiological stress, as measured by salivary hormones and markers of mucosal immunity, during an Antarctic expedition.
A 36-y-old man (188.2 cm height, 94.5 kg body mass) took part in a world-record attempt. A total-body dual-energy X-ray absorptiometry scan and measurement of 8 skinfolds and 5 girths were performed before and after the expedition. In addition, daily subjective data were recorded (sleep quality, total hours of sleep, energy levels, perceived exertion, mood, muscle soreness, and muscle/joint pain) along with distance covered and hours of physical activity per day. As a measure of cognitive function, the athlete completed a computerized battery of tasks (Axon Sports Cognitive Priming Application) every third morning. Saliva samples were collected before, during, and after the expedition to determine salivary cortisol (sCort), testosterone (sT), alpha amylase (sAA), and secretory immunoglobulin A (sIgA).
The athlete lost 5.3 kg body mass and sum of 8 skinfolds decreased from 73 mm to 59 mm from preexpedition to postexpedition. Psychomotor speed declined over the course of the expedition. sT increased and sCort decreased throughout, and sAA and sIgA peaked toward the end of the expedition.
This case study provides novel data about the physiological and cognitive impact of an Antarctic expedition. The findings may inform strategies for future expeditions, allowing individuals undertaking expeditions of this nature to better prepare for success.
Amy E. Mark and Ian Janssen
Despite the plethora of research examining the physical activity-adiposity relation in youth, questions remain regarding the ideal intensity. Therefore, the purpose of this study was to explore the independent effects of physical activity intensity and incidental movement on total and trunk adiposity.
The sample consisted of 1165 youth aged 8 to 17 years from the 2003−04 U.S. National Health and Nutrition Examination Survey. Physical activity (low, moderate, vigorous intensity) and incidental movement (activity level when not physically active) were measured using Actigraph accelerometers over 7 days. Total body and trunk fat were measured using dual-energy X-ray absorptiometry; age- and sex-specific percentile scores were calculated.
Bivariate analyses revealed an inverse relation between total, low, moderate and vigorous intensity physical activity with total body and trunk fat. After consideration of the total volume of physical activity in the multivariate analyses, moderate-to-vigorous intensity physical activity remained significantly related to total and trunk fat. Participants with the highest (top 12.5%) moderate-to-vigorous intensity activity values had total fat percentile scores that were 34 points lower than participants with the lowest (bottom 25%) values.
These results are consistent with public health guidelines which recommend that children and youth participate in moderate-to-vigorous intensity physical activity.
Alex S. Ribeiro, Fábio Luiz C. Pina, Soraya R. Dodero, Danilo R. P. Silva, Brad J. Schoenfeld, Paulo Sugihara Júnior, Rodrigo R. Fernandes, Décio S. Barbosa, Edilson S. Cyrino and Julio Tirapegui
The aim of this study was to analyze the effects of 8 weeks of conjugated linoleic acid (CLA) supplementation associated with aerobic exercise on body fat and lipid profile on obese women. We performed a randomized, double-blinded and placebo-controlled trial with 28 obese women who received 3.2 g/day of CLA or 4 g/day of olive oil (placebo group) while performing an 8-week protocol of aerobic exercise. Dietary intake (food record), body fat (dual-energy X-ray absorptiometry), and biochemical analysis (blood sample) were assessed before and after the intervention period. Independent of CLA supplementation, both groups improved (p < .05) oxygen uptake (CLA group, 13.2%; PLC group, 14.8%), trunk fat (CLA group, −1.0%; PLC group, −0.5%), leg fat (CLA group, −1.0%; PLC group, −1.6%), and total body fat (CLA group, −1.7%; PLC group, −1.3%) after the 8-week intervention. No main effect or Group × Time interaction was found for total cholesterol, triglycerides, and plasma lipoproteins (p > .05). We conclude that CLA supplementation associated with aerobic exercise has no effect on body fat reduction and lipid profile improvements over placebo in young adult obese women.
Gladys Block, Christopher D. Jensen, Torin J. Block, Jean Norris, Tapashi B. Dalvi and Ellen B. Fung
Understanding and increasing physical activity requires assessment of occupational, home, leisure and sedentary activities.
A physical activity questionnaire was developed using data from a large representative U.S. sample; includes occupational, leisure and home-based domains; and produces estimates of energy expenditure, percent body fat, minutes in various domains, and meeting recommendations. It was tested in 396 persons, mean age 44 years. Estimates were evaluated in relation to percent body fat measured by dual-energy x-ray absorptiometry.
Median energy expenditure was 2,365 kcal (women) and 2,960 kcal (men). Women spent 35.1 minutes/day in moderate household activities, 13.0 minutes in moderate leisure and 4.0 minutes in vigorous activities. Men spent 18.0, 22.5 and 15.6 minutes/day in those activities, respectively. Men and women spent 276.4 and 257.0 minutes/day in sedentary activities. Respondents who met recommendations through vigorous activities had significantly lower percent body fat than those who did not, while meeting recommendations only through moderate activities was not associated with percent body fat. Predicted and observed percent body fat correlated at r = .73 and r = .82 for men and women respectively, P < .0001.
This questionnaire may be useful for understanding health effects of different components of activity, and for interventions to increase activity levels.
Katherine A. Beals and Amanda K. Hill
The purpose of this study was to examine the prevalence of disordered eating (DE), menstrual dysfunction (MD), and low bone mineral density (BMD) among US collegiate athletes (n = 112) representing 7 different sports (diving, swimming, x-country, track, tennis, field hockey, and softball) and determine differences in prevalence existed between athletes participating in lean-build (LB) and non-lean build (NLB) sports. DE and MD were assessed by a health, weight, dieting, and menstrual history questionnaire. Spinal BMD was determined via dual energy x-ray absorptiometry. Twenty-eight athletes met the criteria for DE, twenty-nine for MD, and two athletes had low BMDs (using a Z score below −2.0). Ten athletes met the criteria for two disorders (one with disordered eating and low BMD and nine with disordered eating and menstrual dysfunction), while only one athlete met the criteria for all three disorders. Using a Z score below −1.0, two additional athletes met the criteria for all three disorders and three more athletes met the criteria for a combination of two disorders. With the exception of MD, which was significantly more prevalent among LB vs. NLB sports (P = 0.053), there were no differences between the groups in the prevalence of individual disorders or combinations of disorders. These data indicate that the combined prevalence of DE, MD, and low BMD among collegiate athletes is small; however, a significant number suffer from individual disorders of the Triad.
Heidi L. Petersen, C. Ted Peterson, Manju B. Reddy, Kathy B. Hanson, James H. Swain, Rick L. Sharp and D. Lee Alekel
This study determined the effect of training on body composition, dietary intake, and iron status of eumenorrheic female collegiate swimmers (n = 18) and divers (n = 6) preseason and after 16 wk of training. Athletes trained on dryland (resistance, strength, fexibility) 3 d/wk, 1.5 h/d and in-water 6 d/wk, nine, 2-h sessions per week (6400 to 10,000 kJ/d). Body-mass index (kg/m2; P = 0.05), waist and hip circumferences (P ≤ 0.0001), whole body fat mass (P = 0.0002), and percentage body fat (P ≤ 0.0001) decreased, whereas lean mass increased (P = 0.028). Using dual-energy X-ray absorptiometry, we found no change in regional lean mass, but fat decreased at the waist (P = 0.0002), hip (P = 0.0002), and thigh (P = 0.002). Energy intake (10,061 ± 3617 kJ/d) did not change, but dietary quality improved with training, as refected by increased intakes of fber (P = 0.036), iron (P = 0.015), vitamin C (P = 0.029), vitamin B-6 (P = 0.032), and fruit (P = 0.003). Iron status improved as refected by slight increases in hemoglobin (P = 0.046) and hematocrit (P = 0.014) and decreases in serum transferrin receptor (P ≤ 0.0001). Studies are needed to further evaluate body composition and iron status in relation to dietary intake in female swimmers.
Gary Slater, David Jenkins, Peter Logan, Hamilton Lee, Matthew Vukovich, John A. Rathmacher and Allan G. Hahn
This investigation evaluated the effects of oral β-Hydroxy-β-Methylbutyrate (HMB) supplementation on training responses in resistance-trained male athletes who were randomly administered HMB in standard encapsulation (SH), HMB in time release capsule (TRH), or placebo (P) in a double-blind fashion. Subjects ingested 3 g · day−1 of HMB or placebo for 6 weeks. Tests were conducted pre-supplementation and following 3 and 6 weeks of supplementation. The testing battery assessed body mass, body composition (using dual energy x-ray absorptiometry), and 3-repetition maximum isoinertial strength, plus biochemical parameters, including markers of muscle damage and muscle protein turnover. While the training and dietary intervention of the investigation resulted in significant strength gains (p < .001) and an increase in total lean mass (p = .01), HMB administration had no influence on these variables. Likewise, biochemical markers of muscle protein turnover and muscle damage were also unaffected by HMB supplementation. The data indicate that 6 weeks of HMB supplementation in either SH or TRH form does not influence changes in strength and body composition in response to resistance training in strength-trained athletes.