Effects of dietary restraint and oral contraceptives on bone strength and bone turnover in young women

ABSTRACT Introduction The purpose of this study was to assess specific osteoporosis-related health behaviours and physiological outcomes including daily calcium intake, physical activity levels, bone strength, as assessed by quantitative ultrasound, and bone turnover among women between the ages of 18 and 25. Respective differences on relevant study variables, based on dietary restraint and oral contraceptive use were also examined. Methods One hundred women (20.6 ± 0.2 years of age) volunteered to participate in the study. Informed written consent was obtained by all subjects prior to participation. The study and all related procedures were approved by the Brock University Research Ethics Board. Body mass, height, relative body fat, as well as chest, waist and hip circumferences were measured using standard procedures. The 10-item restrained eating subscale of the Dutch Eating Behaviour Questionnaire (DEBQ) was used to assess dietary restraint (van Strien et al., 1986). Daily calcium intake was assessed by the Rapid Assessment Method (RAM) (Hertzler & Frary 1994). Weekly physical activity was documented by the 4-item Godin Leisure-Time Exercise Questionnaire (Godin & Shephard 1985). Bone strength was determined from the speed of sound (SOS) as measured by QUS (Sunlight 7000S). SOS measurements (m/s) were taken of the dominant and non-dominant sides of the distal one third of the radius and the mid-shaft of the tibia. Resting blood samples were collected from all subjects between 9am and 12pm, in order to evaluate the impact of lifestyle factors on biochemical markers of bone turnover. Blood was collected during the early follicular phase of the menstrual cycle (approximately days 1-5) for all subjects. Samples were centrifliged and the serum or plasma was aliquoted into separate tubes and stored at -80°C until analysis. The bone formation markers measured were Osteocalcin (OC), bone specific alkaline phosphatase (BAP) and 25-OH vitamin D. The bone resorption markers measured were the carboxy (CTx) and amino (NTx) terminal telopeptides of type-I collagen crosslinks. All markers were assessed by ELISA. Subjects were divided into high (HDR) and low dietary restrainers (LDR) based on the median DEBQ score, and also into users (BC) and non-users (nBC) of oral contraceptives. A series of multiple one way ANOVA's were then conducted to identify differences between each set of groups for all relevant variables. A two-way ANOVA analysis was used to explore significant interactions between dietary restraint and use of oral contraceptives while a univariate follow-up analysis was also performed when appropriate. Pearson Product Moment Correlations were used to determine relationships among study variables. Results HDR had significantly higher BMI, %BF and circumference measures but lower daily calcium intake than LDR. There were no significant differences in physical activity levels between HDR and LDR. No significant differences were found between BC and nBC in body composition, calcium intake and physical activity. HDR had significantly lower tibial SOS scores than LDR in both the dominant and non-dominant sites. The post-hoc analysis showed that within the non-birth control group, the HDR had significantly lower tibial SOS scores of bone strength when compared to the LDR but Aere were no significant differences found between the two dietary restraint groups for those currently on birth control. HDR had significantly lower levels of OC than LDR and the BC group had lower levels of BAP than the nBC group. Consistently, the follow-up analysis revealed that within those not on birth control, subjects who were classified as HDR had significantly (f*<0.05) lower levels of OC when compared with LDR but no significant differences were observed in bone turnover between the two dietary restraint groups for those currently on birth control. Physical activity was not correlated with SOS scores and bone turnover markers possibly due to the low physical activity variability in this group of women. Conclusion This is the first study to examine the effects of dietary restraint on bone strength and turnover among this population of women. The most important finding of this study was that bone strength and turnover are negatively influenced by dietary restraint independent of relative body fat. In general, the results of the present thesis suggest that dietary restraint, oral contraceptive use, as well as low daily calcium intake and low physical activity levels were widespread behaviours among this population of college-aged women. The young women who were using dietary restraint as a strategy to lose weight, and thus were in the HDR group, despite their higher relative body fat and weight, had lower scores of bone strength and lower levels of markers of bone turnover compared to the low dietary restrainers. Additionally, bone turnover seemed to be negatively affected by oral contraceptives, while bone strength, as assessed by QUS, seemed unaffected by their use in this population of young women. Physical activity (weekly energy expenditure), on the other hand, was not associated with either bone strength or bone tiimover possibly due to the low variability of this variable in this population of young Canadian women.

Factors affecting performance proficiency : a case study involving intermediate piano students

The goal of this study was to determine the effect of a number of factors on the performance proficiency of three intermediate piano students having different learning styles, all of whom shared the same teacher. Four sets of data were collected in this investigation: the methodology of the teacher; the practice behaviour of the participants; the effect of intrinsic factors, such as participant attitude, motivation, and ownership of learning; and the effect of extrinsic factors that included parental influence, and participants' school- and employment-related responsibilities. Performance proficiency and assessment of practice behaviour were measured by three external, professionallyqualified music examiners. Performance proficiency varied to some extent between participants, but they shared similar practice behaviours. Learning style does not, therefore, affect practice behaviour. Although they planned their practice time, participants did not show much evidence of monitoring the quality of their practice. On the other hand, participants showed positive attitude; they were motivated to learn; and they were observed to plan their practice time, all indicators of, among other things, positive influence of the teacher and parents. Participants showed evidence that these constructive habits were a denominator common to both their schoolwork and piano practice. It was apparent that, except for learning style, all factors examined had an effect on performance proficiency. Performance proficiency is, therefore, influenced by a large web of factors, a finding that is instructive for classroom teachers. Teachers need to avoid the temptation to teach toward performance expectations. Emphasis should be placed instead on teaching and assessing formative learning strategies.

Development of a New Assessment System to Evaluate Students' English Communicative Capacities in China

The purpose of this study was to develop a new English assessment system to evaluate Chinese students' English communicative capacities. Since there is more interaction with people from English-speaking countries, Chinese people attach more importance to English oral skills, and a lot of Western English teaching methods were introduced into China to improve students' English communicative capacities. However, traditional paper-written examinations, like the English test of higher education entry examination, cannot evaluate it effectively. This study explored the perceptions of two Chinese English-language teachers and two Chinese students about English assessment system. A qualitative research method using telephone interviews was conducted in this study. The findings showed that the most possible ways to assess Chinese students' English communicative capacities were paper-written examination and person-machine conversations, although measures should be taken to improve these two models. On the other hand, the model of person-person conversation was the ideal assessment tool but was hard to achieve at the current stage.