Susanne Ring-Dimitriou

Effect of exercise intervention on thigh muscle volume and anatomical cross‐sectional areas—Quantitative assessment using MRI

The objective of this study was to evaluate the location‐specific magnitudes of an exercise intervention on thigh muscle volume and anatomical cross‐sectional area, using MRI. Forty one untrained women participated in strength, endurance, or autogenic training for 12 weeks. Axial MR images of the thigh were acquired before and after the intervention, using a T1‐weighted turbo‐spin‐echo sequence (10 mm sections, 0.78 mm in‐plane resolution). The extensor, flexor, adductor, and sartorius muscles were segmented between the femoral neck and the rectus femoris tendon. Muscle volumes were determined, and anatomical cross‐sectional areas were derived from 3D reconstructions at 10% (proximal‐to‐distal) intervals. With strength training, the volume of the extensors (+3.1%), flexors (+3.5%), and adductors (+3.9%) increased significantly (P < 0.05) between baseline and follow‐up, and with endurance training, the volume of the extensor (+3.7%) and sartorius (+5.1%) increased significantly (P < 0.05). No relevant or statistically significant change was observed with autogenic training. The greatest standardized response means were observed for the anatomical cross‐sectional area in the proximal aspect (10–30%) of the thigh and generally exceeded those for muscle volumes. The study shows that MRI can be used to monitor location‐specific effects of exercise intervention on muscle cross‐sectional areas, with the proximal aspect of the thigh muscles being most responsive. Magn Reson Med, 2010.

Plasma adiponectin and insulin sensitivity in overweight and normal-weight middle-aged premenopausal women

Adiponectin has been reported to regulate systemic insulin sensitivity as a part of a broader control mechanism in energy balance. However, it is not clear whether adiponectin exerts its positive effects on insulin sensitivity equally in a wide range of obesity. We investigated the association of plasma adiponectin concentration with insulin resistance (IR) in a cross-sectional sample of 98 middle-aged premenopausal women with a wide range of obesity. In addition, we studied the relationship between adiponectin, body composition, and blood biochemical and cardiorespiratory fitness variables. Body composition and fat distribution were measured via dual-energy x-ray absorptiometry in normal-weight (NW) (n = 41, body mass index [BMI] < 25 kg/m(2)) and overweight (OW) (n = 57, BMI > or = 25 kg/m(2)) women. Fasting blood samples were obtained; adiponectin, leptin, insulin, glucose, and insulin-like growth factor-I were measured; and IR index was calculated. The IR index from fasting plasma insulin and plasma glucose levels was estimated using the homeostasis model assessment (HOMA), as follows: fasting plasma insulin (in microliter units per milliliter) x fasting plasma glucose (in millimoles per liter)/22.5. Adiponectin was significantly higher (P = .0001) in NW (14.7 +/- 4.7 microg/mL) compared with OW (9.9 +/- 3.1 microg/mL) women. Significant differences (P < .003) in body mass, BMI, percentage of fat mass, fat mass, trunk fat, trunk fat-leg fat ratio, leptin, insulin, and HOMA were also observed between NW and OW groups. Leptin was independently related to plasma adiponectin (beta = -.259, P = .001) in the overall study group. Plasma adiponectin was only related to trunk fat-leg fat ratio (beta = -.242, P = .002) among NW subjects, whereas plasma adiponectin was related to fat-free mass (beta = .182, P = .0001) and HOMA (beta = -.576, P = .002) among OW women. The inverse relationship between adiponectin and leptin concentrations suggests that leptin may be involved in the regulation of adiponectin in middle-aged premenopausal women. Our data also demonstrate that adiponectin may play an important role in sustaining insulin sensitivity only in OW middle-aged premenopausal women.

Effects of Exercise Intervention on Knee Morphology in Middle-Aged Women: A Longitudinal Analysis Using Magnetic Resonance Imaging

Introduction:Epidemiological studies show a positive relationship between physical activity and cartilage volume, suggesting that exercise may protect against osteoarthritis. Cross-sectional experimental studies, however, have failed to show significant differences in knee cartilage morphology between athletes and nonathletic controls. The aim of the study was to test the hypothesis that knee cartilage morphology, specifically regional cartilage thickness and global subchondral bone area, is modified in sedentary, untrained adult women who increased their physical fitness during a 3-month supervised exercise intervention. Materials and Methods: Thirty-eight untrained women, aged 45–55 years, were randomly assigned to: endurance training (n = 18), strength training (n = 15) and autogenic training (control group, n = 5). Patellar and femorotibial knee cartilage morphology was determined before and after the 3-month supervised training intervention, using magnetic resonance imaging and state-of-the-art image analysis. Results: Whereas the endurance training group showed a significant increase in cardiorespiratory fitness and the strength training group a significant increase in the maximal voluntary isometric contraction force of the leg, this study did not show significant differences in knee cartilage thickness and volume, subchondral bone area or regional cartilage thickness between baseline and follow-up acquisitions within any intervention group. Discussion:This randomized longitudinal study provides no evidence that a 3-month exercise intervention in untrained middle-aged women can significantly alter knee joint morphology. Longitudinal evidence supporting that a training program, successful in increasing physical fitness, can also induce functional adaptation of articular tissues and may protect against knee osteoarthritis, remains to be presented.

The Single Nucleotide Polymorphism Gly482Ser in the PGC-1α Gene Impairs Exercise-Induced Slow-Twitch Muscle Fibre Transformation in Humans

PGC-1α (peroxisome proliferator-activated receptor γ co-activator 1α) is an important regulator of mitochondrial biogenesis and a master regulator of enzymes involved in oxidative phosphorylation. Recent evidence demonstrated that the Gly482Ser single nucleotide polymorphism (SNP) in the PGC-1α gene affects insulin sensitivity, blood lipid metabolism and binding to myocyte enhancer factor 2 (MEF2). Individuals carrying this SNP were shown to have a reduced cardiorespiratory fitness and a higher risk to develop type 2 diabetes. Here, we investigated the responses of untrained men with the Gly482Ser SNP to a 10 week programme of endurance training (cycling, 3 x 60 min/week, heart rate at 70-90% VO2peak). Quantitative data from analysis of biopsies from vastus lateralis muscle revealed that the SNP group, in contrast to the control group, lacked a training-induced increase in content of slow contracting oxidative fibres. Capillary supply, mitochondrial density, mitochondrial enzyme activities and intramyocellular lipid content increased similarly in both groups. These results indicate that the impaired binding of MEF2 to PGC-1α in humans with this SNP impedes exercise-induced fast-to-slow muscle fibre transformation.

Relative Distribution of Quadriceps Head Anatomical Cross-Sectional Areas and Volumes – Sensitivity to Pain and to Training Intervention

INTRODUCTION Quadriceps heads are important in biomechanical stabilization and in the pathogenesis osteoarthritis of the knee. This is the first study to explore the relative distribution of quadriceps head anatomical cross-sectional areas (ACSA) and volumes, and their response to pain and to training intervention. METHODS The relative proportions of quadriceps heads were determined in 48 Osteoarthritis Initiative participants with unilateral pain (65% women; age 45-78 years). Quadriceps head volumes were also measured in 35 untrained women (45-55 years) before and after 12-week training intervention. Cross-sectional areas of the vastus medialis (VM), inter-medius (VIM), and lateralis (VL), and of the rectus femoris (RF) were determined from axial T1-weighted MR images. RESULTS The proportion of the VM on the total quadriceps ACSA increased from proximal to distal. The difference in quadriceps ACSA of painful (vs. pain-free) limbs was -5.4% for the VM (p<0.001), -6.8% for the VL (p<0.01), -2.8% for the VIM (p=0.06), and +3.4% for the RF (p=0.67) but the VM/VL ratio was not significantly altered. The muscle volume increase during training intervention was +4.2% (p<0.05) for VM, +1.3% for VL, +2.0% for VIM (p<0.05) and +1.6% for RF. CONCLUSION The proportion of quadriceps head relative to total muscle ACSA and volume depends on the anatomical level studied. The results suggest that there may be a differential response of the quadriceps heads to pain-induced atrophy and to training-related hypertrophy. Studies in larger samples are needed to ascertain whether the observed differences in response to pain and training are statistically and clinically significant.

Geschlechtsunterschiede bei psychologischen, ernährungs- und sportwissenschaftlichen Einflussfaktoren auf Adipositas/Übergewicht bei Kindern und Jugendlichen in Österreich

ZusammenfassungDas Ess- und Bewegungsverhalten unterliegt der Steuerungsfunktion durch bestimmte kognitive Muster. Es werden im Folgenden, zur Darstellung von eventuell durchgehenden Geschlechtertrends, die bei 4400 Kindern/Jugendlichen und 6600 Erwachsenen mit dem Adipositas Diagnostik- und Evalutionssystem (AD-EVA) gemessenen Unterschiede in der Teilgruppe der Adipösen dargestellt.Höhere Werte ungünstiger psychischer Steuerungsmechanismen des Ess- und Bewegungsverhaltens adipöser Mädchen liegen vor allem im Bereich der vorklinischen Essstörungen. Diese Ergebnisse sind für Prävention und Gesundheitsförderung relevant.Interessant sind auch die nicht-signifikanten Unterschiede im Bereich der Einstellung zu Bewegung wie der Bewegungsmotivation. Es würde bedeuten, dass man nicht dem Vorurteil aufsitzen darf, dass das männliche Geschlecht ohnehin mehr Freude an der Bewegung habe.Die männliche Vorliebe für „Snacks“ und „Deftiges“ konnte in der für Österreich repräsentativen Normstichprobe des Fragebogensystems AD-EVA repliziert werden, spiegelt sich aber nicht in der Teilgruppe der adipösen Mädchen und Knaben. Man kann davon ausgehen, dass sich 8- bis 18-jährige Adipöse beiderlei Geschlechts ungünstig ernähren.SummaryEating behavior and physical activity behavior are under the control of certain cognitive patterns. 6600 adults and 4400 children/adolescents (8–18 years) were tested with the Obesity Diagnostics and Evaluation System (AD-EVA). Potentially significant gender differences will be detailed for the entire juvenile cohort, the subgroup of obese children/adolescents as compared to the adult cohort in this article.Among all the subscales tested, obese girls primarily showed significantly higher values of (preclinical) eating disorders than boys. These data are relevant for both prevention and health promotion.No significant differences were found in regard to sports motivation. This warrants facilitation of physical activity for both genders. Further, a male predilection for “Snacks” and “High-fat food” that could be found in the total representative study group, could not be verified in the subgroup of obese girls and boys, thus suggesting a similarily unhealthy eating behavior in both genders of juvenility.

SALTO - Study Protocol and Rationale of a Community-Oriented Obesity Prevention Program in the Kindergarten

Background: The prevalence of early childhood overweight and obesity in Austria has reached average European levels of 20% in boys and 18% in girls. The rationale and study protocol of SALTO, Salzburg Together against Obesity will be presented, which is aimed to assist adults in increasing the rate of 4- to 6-year-old children with a healthy body weight. Methods: A controlled longitudinal sequential study design consisting of 14 intervention (IK) and 8 control (CK) kindergarten was used to investigate the effect of actions tailored for teachers and parents on BMI among 4- to 6-year-old children. The study launched in November 2014 was approved by the ethics committee of the University of Salzburg. Results: 681 children, 181 parents (119 mothers, 62 fathers) and 30 teachers were investigated until October 2016. Preliminary analyses revealed that more boys (19%) and fathers (60% IK, 43% CK) were overweight and obese than girls (16%) and mothers (19% IK, 20% CK). Conclusion: The challenges faced by the SALTO staff in the implementation of health-promoting actions in the kindergarten are manifold. The Community-Oriented Core Setting (COCS) intervention approach will show whether the actions will reduce the percentage of obesity and be sustainable in the long term.

Psychological, Nutritional and Sports-Scientific Aspects of Obesity in Adolescence

Meta-analyses show that weight loss through conservative therapy and prevention does not indicate any big changes (Ebbeling et al. 2002; Miller and Jacob 2001). What is it specifically that makes it so difficult for obese adolescents to lose weight and puts so much stress on their life?