Thesis (M.Sc. (Human Movement Science))--North-West University, Potchefstroom Campus, 2009.

Purpose: To determine the association of certain aerobic fitness and physical activity genotypes and the gene-physical activity interaction effect on aerobic fitness in pre-pubertal, African American, obese children. Methods: Subjects were 30 pre-pubertal, African American, obese children (9.5 ± 1.7 years) who were free of clinical disease. Height and weight were measured according to standard procedures. Body fat was assessed using dual energy x-ray absorptiometry, and DNA samples were collected using buccal swabs. Aerobic fitness was assessed using a cycle ergometer and the McMaster cycle protocol. ANOVAs were used to determine associations and interaction effects of the ACE, ADRB2, NOS3, IL6, IGF-1, and APO-E genes, physical activity and aerobic fitness. Results: Age, height, weight, body mass index, and waist circumference were significantly lower in girls compared to boys. Subjects averaged approximately 51 minutes of moderate-to-vigorous intensity activity per day, and girls were significantly more active than boys. There were no significant associations between the candidate genes and aerobic fitness level. P > 0.05). There were trends towards significance for the IL6 rs2069845 gene for absolute and relative VO2peak measures (P = 0.078, and P = 0.094, respectively). There was also a trend toward significance for the ADRβ2 rs1042717 gene for leanVO2peak (P = 0.092). Conclusions: In children, further research is needed that includes diverse populations and large sample sizes in order to more accurately assess the association and interaction effects of the candidate genes, physical activity and fitness.

Als Resultat überhöhter Energieaufnahme und zu geringen Energieverbrauchs beobachten wir eine über das normale Maß hinausgehende Akkumulation von Fettgewebe, die sich als Adipositas manifestiert. Sie gilt als einer der Hauptrisikofaktoren für Krankheiten des metabolischen Syndroms. Im Rahmen von Prävention, Diagnose und Therapie der Adipositas, muss ihr wesentliches Charakteristikum; der individuelle Körperfettanteil; einer Messung zugänglich gemacht werden. Eine direkte Bestimmung der Körperzusammensetzung erlauben die Neutronenaktivierungsanalyse und die chemische Analyse. Beide Verfahren sind sehr genau, aber aufwendig und kostenintensiv und darüber hinaus die chemische Analyse nur am menschlichen Cadaver praktizierbar. Um dennoch die Körperzusammensetzung hinreichend genau bestimmen zu können, wurden zahlreiche indirekte Messverfahren entwickelt. Man kann sie in Labor- und Feldmethoden untergliedern. Die Labormethoden bestechen durch hohe Genauigkeit und Reproduzierbarkeit, sind aber zumeist aufwendig und teuer. Feldmethoden sind im Gegensatz dazu leicht anwendbar, transportabel und preiswert, weisen aber eine weniger hohe Genauigkeit und Reproduzierbarkeit auf.<br><br> In der vorgestellten Arbeit wird über eine jüngere Entwicklung, die das Prinzip der unterschiedlichen Leitfähigkeit für den elektrischen Strom durch die verschiedenen Gewebe des Körpers nutzt, berichtet. Der Prototyp eines Gerätes wurde innerhalb eines von der EU geförderten multizentrischen Projekts entwickelt und auf seine Einsatzfähigkeit und Qualität hin geprüft. Der Schwerpunkt der Arbeit liegt auf der Einschätzung der Körperzusammensetzung normal- und übergewichtiger Probanden mit der neu entwickelten Technik. Das vorliegende Studiendesign diente nicht nur der Beurteilung der neuen Technik die Körperzusammensetzung und Veränderungen dieser zu erfassen, sondern darüber hinaus, etablierte Methoden hinsichtlich ihrer Genauigkeit zu bewerten. Bezüglich ihrer Anwendbarkeit und Reproduzierbarkeit hat die neue Methode Hoffnung geweckt, sich als eine Feldmethode zu etablieren. Auf der anderen Seite zeigte sich in Abhängigkeit der Gesamtkörperfettmasse eine Überschätzung der Zielgröße im Vergleich zur Referenzmethode (dual energy x ray absorptiometry (DXA)). Die Abweichungen waren dabei gerade für das einzelne Individuum sehr groß. Technische Verbesserungen und die Entwicklung spezifischer Regressionsgleichungen könnten in Zukunft zu einer wesentlichen Verbesserung der neuen Methode beitragen.<br><br> Die Labormethode "Air Displacement Plethysmography" konnte durch die guten Übereinstimmungen der Ergebnisse mit denen der Referenzmethode DXA und die einfache Anwendung überzeugen. Sie stellt eine durchaus konkurrenzfähige Alternative zur Hydrodensitometrie dar, die noch heute als "goldener Standard" zur Erfassung der Körperzusammensetzung akzeptiert wird. Im Verlauf der durchgeführten Studie stellte sich heraus, dass die Hydrodensitometrie sehr hohe Anforderungen an den Probanden stellt. Das Untertauchen des gesamten Körpers unter Wasser in Kombination mit einer maximalen Ausatmung erwies sich als sehr problematisch. Die dabei auftretenden Fehler schlugen sich in der Berechnung der Gesamtkörperfettmasse des einzelnen Individuums wieder und führten zu zum Teil erheblichen Abweichungen der Ergebnisse von denen der Referenzmethode.<br><br> Die Feldmethoden bioelektrische Impedanzanalyse und Hautfaltendickenmessung erwiesen sich als kostengünstige und leicht anwendbare Methoden. Die Ergebnisse beider Methoden stimmten im Mittel gut mit den Ergebnissen der Referenzmethoden überein. Dennoch zeigte die BIA größere Abstriche in der Beurteilung der Gesamtkörperfettmasse des einzelnen Individuums und bei der Dokumentation von Veränderungen der Gesamtkörperfettmasse. Die Hautfaltendickenmessung stellt – wendet man sie korrekt an – eine Methode dar, die sowohl die Gesamtkörperfettmasse als auch Veränderungen dieser gut erfassen kann. In Abhängigkeit der geforderten Genauigkeit kann diese Methode für die Erfassung der Körperzusammensetzung empfohlen werden.<br><br> Demnach bleibt die Frage unbeantwortet, inwieweit die indirekten Methoden in der Lage sind, die "wahre" Körperzusammensetzung adäquat zu erfassen. Jede neu entwickelte Methode – die möglichst viele Vorteile in sich vereint – wird wieder vor dem Problem stehen: eine geeignete und dabei praktikable Referenzmethode zu finden, die die wahre Körperzusammensetzung zu bestimmen in der Lage ist. Daher sollte neben dem Streben nach der Entwicklung einer Methode, die genau und leicht anwendbar ist, das Hauptaugenmerk auf die Überarbeitung der zugrunde liegenden Modellvorstellungen und die Verbesserung von Regressionsgleichungen gelegt werden. / Western industrial countries are characterized by sedentary lifestyle and a high-fat and simple carbohydrate diet. Decrease physical activity and increase energy intake are leading to an epidemic increase of overweight and obesity. Obesity is defined as the presence of excess adipose tissue and has been associated with an increased risk for diseases of the metabolic syndrome. Thus, the importance of obtaining reliable and accurate body fat estimates is essential not only for the prevention, but also for the diagnosis and therapy of obesity. Direct chemical analysis is the most definitive method for determining human body composition. The few data obtained on the composition of adult bodies stemmed from cadaver analyses, dated back to 1945 and 1956. These results contributed greatly to the actual fundamental knowledge about human body composition. Obviously, the method is limited by the precondition of needing the human cadaver and the high complexity of the analyses. Because of this limitation, indirect methods have been developed during the last decades. To date more than ten methods to estimate body composition in vivo are available. The methods can be generally organized into two groups: laboratory and fields methods. Laboratory methods have high accuracy and reproducibility, but are complex and very expensive, whereas field methods are easy to use and economically priced, but less accurate. A new device that combines the positive features of both, laboratory and field methods is needed . An already existing method - Total Body Electrical Conductivity (TOBEC) - meets the requirements for such new device. The technique is based on the principle, that lean tissue is far more electrically conductive than fat, due to the higher content of electrolytes in the fat-free mass. The difference between impedance when a subject is inside and outside of the generated field is an index of the total electrical conductivity of the body, which, in turn is proportional to the lean body mass of the subject.<br><br> Within the European Project BodyLife (IST - 2000 - 25410) a new field method for estimation the human body composition was developed. To assess the suitability of the new technique the present study aimed to evaluate the reliability of nTOBEC and to validate it against established laboratory and field methods.<br><br> Within the project the development of the new method (nTOBEC) succeeded to combine the TOBEC-principle, and additionally, to be transportable and easy to use.<br><br> The high reliability coefficients found in this investigation indicate that nTOBEC is an extremely reliable instrument. By application the new technique we observed a significant overestimation of total body fat mass compared the reference method dual energy x ray absorptiometry (DXA) in both, males and females. However, nTOBEC could document changes in total body fat mass during a weight loss intervention trial.<br> Our data suggest nTOBEC deserves further investigation with the intention of establishing nTOBEC as a non-invasive method for accurately quantifying total body fat mass.<br> Aside from these results we observed accurate results for the easy to use laboratory method "air displacement plethysmography" compared to the results measured by DXA. Furthermore, the field methods - bioelectrical impedance analysis and skinfold thickness measurement – produced good results compared to the reference method.

Background Excess adipose tissue and low physical activity are two major determinants for chronic diseases such as type 2 diabetes and cardiovascular disease.  Understanding these relationships requires accurate and precise measures of body composition and physical activity, and most existing observational studies lack such measures. Paper I to III in this thesis addresses the validity of measures of physical activity and abdominal adipose mass. In paper IV and V, we explore the relationships between obesity and physical activity on metabolic health in non-pregnant and pregnant women and their offspring. Methods and Results Two hundred men and women representative of the Northern Sweden EPIC cohort were recruited for Paper I. A questionnaire on physical activity (PAQ) was validated against objectively measured physical activity energy expenditure (PAEE). A categorical physical activity index (Cambridge index) calculated from PAQ showed strongest correlation with PAEE (r=0.33 p&lt;0.05). In Paper II, abdominal adiposity were assessed in 29 adult men and women using anthropometric measurements, dual energy x-ray absorptiometry (DXA) and ultrasound and were compared to computed tomography (CT). Waist circumference showed the highest correlation with CT-assessed visceral (r=0.85, p&lt;0.0001) and subcutaneous adipose tissue (r=0.86, p&lt;0.0001). Adipose thickness was best assessed with ultrasound. In Paper III, the validity of a wrist-worn triaxial accelerometer was assessed in 32 pregnant and 74 non-pregnant women using double-labeled water method (DLW) as the criterion measure. The output from the accelerometer explained 24% (p &lt;0.001) of the variation in PAEE in non-pregnant and 11% (p&lt;0.05) in the pregnant women. In Paper IV, 35 pregnant and 73 non-pregnant women underwent a 75g oral glucose tolerance test and habitual energy expenditure and physical activity was assessed objectively. Total physical activity was inversely associated with early insulin response in both pregnant (r=-0.47, p=0.007) and non-pregnant (r=-0.36, p=0.004) women. In, Paper V, 32 women and their offspring (n=33) were studied 4 months post-partum. Body composition was quantified using DXA in the women and air-displacement plethysmography  in the infants. Mid-pregnancy weight gain was significantly associated with infant fat mass (r=0.41, p=0.022), whereas late-pregnancy weight gain associated to infant fat-free mass (r=0.37, p=0.04). Conclusion This work describes new methods as well as conventional anthropometric estimates and a questionnaire, that provide relatively strong estimates of body composition and physical activity which could be used in larger studies. Pregnant women were shown to have more sedentary behavior than non-pregnant but physical activity appeared to have equal effect on glucose homeostasis in both groups, which may help guide lifestyle interventions in pregnancy. The impact of weight gain during the different trimesters seems to differentially affect the offspring’s body composition in early infancy, which might give us clues to when different aspects of fetal development and growth occur and how modifiable lifestyle behaviors might be intervened upon to improve long-term health. / Embargo

Accurate measurements of energy content and body composition are essential to effectively assess the well-being of fish. Bomb calorimetry and proximate analysis are currently the most dependable and accurate methods to estimate energy content and body composition. However, bioenergetic studies that employ the traditional methodology necessitate the killing of fish to determine physiological composition and energy content in a target tissue. The killing of the individual negates the ability for repeated measures on the same individual, and also suppresses compositional studies involving endangered or threatened species. Recent research has shown Bioelectrical Impedance Analysis (BIA), a quick, easy-to-use, non-invasive, and most importantly, non lethal technique to be an effective method for estimating the proximate composition and energy content of fish. The focus of this research is to evaluate the capability of BIA to accurately assess the bioenergetics of juvenile rainbow trout (Oncorhynchus mykiss), and to develop species-specific indices to predict energy content, total body water and dry mass. To do this, juvenile rainbow trout were subjected to one of three ration regimes: maintenance (0.4 % bw/day), optimum (1.9 % bw/day) and satiation (3.4 % bw/day) for 90 days. Subsamples from each treatment were taken every 30 days to be subjected to BIA testing. Tissue samples were collected from the subsampled trout for future caloric and compositional analysis via bomb calorimetry and proximate analysis. It was found that BIA demonstrated a strong predictive relationship with regard to energy content (r2 = 0.90), total body water (r2 = 0.89) and dry mass (r2 = 0.80). BIA was also able to successfully reflect a notable statistical difference between treatments with regard to total energy content, energy density, total body water, dry mass. These results, along with much of the existing literature, indicate that BIA may be an accurate and reliable tool to estimate the bioenergetics and proximate composition of fish. / UOIT

The purpose of this study was to compare the accuracy of eight anthropometric regression equations with hydrostatic weighing for predicting the percent body fat of adult males with Down Syndrome (DS). Body fat percentages were predicted for 18 adult males with DS. Skinfold, circumference, and bioelectric impedance analysis data were collected to determine how accurately the regression equations could predict the percent fat of these individuals when compared to hydrostatic weighing. Since hydrostatic weighing involves a number of complex procedures two pilot studies were conducted. Four subjects participated in the pilot studies. The first pilot was conducted to determine if a constant value of residual volume could be utilized during hydrostatic weighing, or if a measured value, determined by oxygen dilution, needed to be used. The second pilot was performed to determine if hydrostatic weighing at total lung capacity without head submersion could be substituted for the conventional method of hydrostatic weighing. Paired t-tests revealed no significant differences in either pilot study, t (3) = .274, p. < .05 and t (3) = .314, 11 < .05, respectively. Pearson product-moment correlations revealed r values of .99 for both pilot studies. Based on these results a constant residual volume value of 1.50 L and hydrostatic weighing at total lung capacity without head submersion were the procedures utilized in the main research study. A one-way repeated measures analysis of variance revealed a significant difference between the body fat data obtained from hydrostatic weighing and the regression equations, F (8, 136) = 16.05, < .05. Dunnett's post-hoc procedure revealed significant differences in five of the eight equations. Of the three equations that did not yield significantly different results, only the Kelly and Rimmer (1987), r = .89, SEE = 2.51, 12 <.05, can be recommended for use. Based on these results, it appears that a constant value of 1.50 L for residual volume and hydrostatic weighing at total lung capacity without head submersion can be utilized when predicting the percent body fat of adult males with DS. This will allow increased numbers of individuals with DS to be hydrostatically weighed. Also, the use of the Kelly and Rimmer (1987) equation will allow researchers and practitioners to utilize an easy, fast, accurate, and inexpensive method of predicting the percent body fat of adult males with DS. / Graduation date: 1992

Mixed results have been reported when body size is used to estimate the effect of health and nutritional status on worker productivity. This dissertation offers an alternative hypothesis that body composition rather than body size is responsible for the effects of health and nutritional status on worker productivity. Body fat is responsible for the poor health associated with obesity. Lean body mass is responsible for the superior performance associated with physical fitness. Studies using body size alone cannot distinguish the combined, but opposite effects, of body fat and lean body mass. A method is provided here that overcomes the lack of data for body composition. The clinical information available in the Third National Health and Nutrition Examination Survey 1988-94 (NHANES III) is used to estimate body composition for the survey participants in the National Longitudinal Survey of Youth (NLSY 1979). The inclusion of estimated body composition in the estimated wage equation shows that the effect of lean body mass on the wage rate is positive while the effect of body fat is negative. Estimated body composition is then used to examine the role of physical differences in the gender wage gap. The decomposition of the gender wage gap shows that most of the previously unexplained differences in wages between men and women can be attributed to the gender differences in body composition. The explanatory power of estimated body composition rises significantly with occupational physical strength requirements. This result suggests that estimated body composition is capturing occupational requirements previously omitted from the past studies. The findings presented in this dissertation indicate that body composition plays an important, though previously unidentified, role on wage determination. It is clear that capital investments in body composition yield economic dividends by impacting hourly wages of workers. Empirical studies that do not address differences in body composition risk obtaining biased results. Future public health policies should take into consideration the combined but opposite effects of body fat and lean body mass. It is not body size alone, but the compositional makeup of the human body, that public health policies may need to address.

The initial recommendation for the postoperative regime after uncemented total hip arthroplasty (THA) was 6-12 weeks of partial weight bearing (PWB) to obtain a stable implant position during bone ingrowth. In recent years patients with uncemented THA have increasingly practiced full weight bearing (FWB) after surgery, which has largely been based on clinical experience rather than on scientific evidence. The aim of this thesis was to investigate the effects of FWB versus PWB for 3 months on the stability of the implants and on bone mineral density (BMD), as well as body composition (BC) of the lower extremities. We used radiostereometric analysis (RSA) to measure implant micromotion and dual X-ray absorptiometry (DXA) to measure BMD and BC. Forty-six patients with strictly unilateral osteoarthritis of the hip (OAH) received uncemented THA. These patients were then randomized to the FWB or PWB groups and followed for 5 years. In a preoperative cross-sectional study the BMD of the hip and heel were compared between the OAH-affected side and the healthy side. The study showed an increase of BMD at the femoral neck and a decrease at the total hip and trochanter. The results of a RSA study of cup stability showed that there might be minimal movement in medial and proximal directions during the first postoperative week. These results indicate that the RSA baseline investigation of uncemented cups should be performed as early as possible after the first postoperative day. FWB had no adverse effects on the stability of the uncemented press-fit cups or the uncemented cementless Spotorno (CLS) femoral stems after a 5-year follow-up. There was no difference in periprosthetic BMD around the CLS stem regardless of the postoperative weight bearing regime. All zones around the femoral stem indicated a recovery in BMD toward baselines, except the calcar region, which showed progressive loss in BMD to -22% at 5 years post-surgery. FWB had no effect on the changes in BC after surgery. In conclusion, FWB is safe in uncemented THA in terms of stability, BMD and BC. Furthermore, THA apparently counteracts age-related changes in BC but not in BMD.

Purpose: To assess the dietary intake and body composition of recreational and competitive female athletes, for the purpose of analyzing the relationships between macronutrient intake and body composition.. The main aim was to determine the relationship between caloric intake, carbohydrate (CHO) intake and protein intake with body fat percentage in active females. Methods: Using an IRB approved protocol, 44 volunteer female recreational and competitive athletes 18 years of age or older were recruited. Interviews were conducted to gather information on within day energy balance by assessing the time and amount of foods/beverages consumed, and the duration and intensity (using a Rating of Perceived Exertion scale) of activity performed on the day of assessment. All analyses were performed using Nutritiming™ (Calorie and Pulse Technologies, Atlanta, GA) to assess energy surpluses, energy deficits, and end of day energy balance. Information on date of birth, race/ethnicity, menstrual status, sleep and wake times, and prior diagnoses of metabolic disease and/or eating disorders were collected at the time of the interview. Height was assessed using a standard stadiometer. Weight and body composition were assessed via Bioelectrical Impedance Analysis (BIA) using InBody 230 (BioSpace Co. USA). The BIA assessment was performed to determine body fat percentage, Basal Metabolic Rate (BMR), Body Mass Index (BMI), segmental body composition, and fat and lean mass in kilograms. Nutrient data were derived using an interviewer-led, 24-hour recall. Results: CHO intake/kg total mass was significantly and inversely correlated with body fat percentage and BMI, (p=0.018 and p=0.001 respectively). Protein intake/kg total mass was also inversely and significantly correlated with body fat percentage (p=0.006). Fat intake was not significantly associated with BMI, body fat percent, or lean mass in kilograms. Total energy intake/kg total mass was inversely associated with BMI (p=0.001), with fat mass (p=0.001), and with body fat percentage, (p=0.001). CHO intake/kg total mass was positively associated with the total number of hours spent in an anabolic (i.e., EB>0) state (p=0.001), and was inversely associated with the total number of hours spent in a catabolic (i.e., EB < 0) state (p=0.001). CHO intake/kg total mass was the only substrate to be significantly correlated with the number of hours spent ± 400 kcal EB over a 24 hour period (p=0.001). Z-scores were created to establish categories of body composition and energy balance values. Utilizing Chi-Square tests, it was determined that more hours spent in an energy surplus (> 400kcal) was associated with higher body fat percent (p=0.042). Conclusions: CHO restriction, whether done intentionally or as a function of an energy restrictive intake, was commonly observed in this subject pool. Of the females surveyed, 79% did not meet their daily energy needs and, on average, consumed 49% of the recommended daily intake of CHO established for active people. The findings that subjects with lower CHO intakes had higher body fat levels, and that CHO was associated with improved maintenance of energy balance, which was also associated with lower body fat percent, suggest that physically active women should not restrict CHO to achieve a desired body composition. It was also observed that end-of-day energy balance was not associated with either energy substrate consumption or body composition.

For the polar bear (<i>Ursus maritimus</i>), a terrestrial carnivore on the highest trophic level in the Arctic marine ecosystem, periods of nutritional restriction or fasting are a characteristic feature of an annual cycle. The overall objective of my thesis was to examine some of the effects of such a 'feast-or-fast' feeding pattern on the body composition, body size and reproductive performance of this Holarctic ursid. As a reproductive strategy, pregnant polar bears occupy maternity dens for up to 6 months between late summer and spring. While in dens, maternal nutrient stores meet all maintenance energy requirements and sustain the nutritional demands of gestation and early lactation. I quantified the nutritional costs of this prolonged 'reproductive fast' in polar bears and examined the effects of variation in maternal body condition on reproductive performance. While fasting, body mass decreased by 43% and of the change in body energy content 93% was attributable to loss of fat. Bears that were fatter priorto denning produced heavier cubs, which would be more likely to survive. Much of the variation in body condition prior to denning was accounted for by age, older females being in better condition. Using an index of milk quality that was closely related to daily milk energy yield, I investigated the independent effects of maternal body condition and age on lactation. Irrespective of condition, older bears tended to produce higher quality milk. While lactation in polar bears is clearly sensitive to body condition, these results also provide strong support for an age-specific increase in reproductive effort among females. Body size is typically a strong determinant of male reproductive success in polygynous mammals such as polar bears. Consequently, theory predicts that mothers in good condition should invest more in male than female offspring in-order to produce large adult males. An underlying assumption of this theory, however, is that early differences in body size among male offspring, such as those apparent by the end of maternal care, will affect their relative adult body size. I tested the validity of this assumption in polar bears and found that, in comparison to females, variation in body size among 2-year-old males was a weak determinant of adult size. I suggest that, in comparison to females, a longer period of growth after maternal care may predispose the adult size of males to a greater degree of environmentally mediated variation. This lack of persistence in relative body size would limit the ability of mothers to affect the adult size of their male offspring, and thus reduce the effectiveness of sex-biased maternal investment as a reproductive strategy in polar bears. One of the principle physiological adaptations enabling animals to go without food for prolonged periods seems to be a heightened ability to minimize the net catabolism of body protein. I quantified changes in the body composition of free-ranging polar bears during the ice-free season. In contrast to previous studies on fasting bears, catabolism of protein appeared to meet a significant proportion of maintenance energy demands in some individuals. (Abstract shortened by UMI.)