Issue 40

I. Doulamis et alii, Frattura ed Integrità Strutturale, 40 (2017) 85-94; DOI: 10.3221/IGF-ESIS.40.08 88 failure. Sample stiffness was calculated as the slope of the linear part of the force/deflection curve while energy as the area below the curve. Ultimate stress was also calculated based on the assumption of elliptical cross-section with constant thickness (t) [21]. Figure 2 : A schematic representation of the three point bending test. The measurement sites for thickness (t 1-4 ) and lengths of the major (right) and minor axis (left) of the samples are also presented. Statistical analysis The results for the three groups were compared to each other and the statistical significance of the differences that were observed was evaluated following one way analysis of variance (ANOVA). The level of statistical significance was con- sidered to be equal to 0.05. The effect of exercise on the biochemical profile and body mass of group C was also investigated. For this purpose one way repeated measures ANOVA (statistical significance level = 0.05) with Bonferroni confidence interval adjustment was used to assess the statistical significance of differences between the measurements that were taken before the start and after the end of the exercise protocol (i.e. week 28 vs 37). In order to assess the relationship between biomechanical and biochemical parameters and the effect of HFD, the cor- relation between the average biomechanical measures for each animal (i.e. average for left and right femur) and the bio- chemical measurements was investigated for groups B and C using Pearson correlation analysis. The correlation between biomechanical measures and body mass was also assessed. All data were tested for linearity, normality and homosce- dasticity. The statistical analyses were performed using IBM® SPSS®v.21. R ESULTS Biochemical measurements t the beginning of the protocol differences between the three groups were non-significant (Fig. 3), with the exception of TG levels, which were somehow higher in group A (an issue that should be considered further). During week 12, the first changes that can be attributed to HFD are observed in the case of HDL-C, with groups B and C having significantly higher HDL-C levels compared to control (group A). Differences in biochemical parameters become clearer during week 28 when significant differences in terms of body mass are also observed. More specifically, groups B and C appear to have significantly higher body mass and higher levels of HDL-C and T-CHOL compared to control. Group C has significantly higher body mass than group B too (average (±STDEV) body mass for groups A, B and C is equal to 29.3kg (±2.4kg) 35.0kg (±4.2kg) and 39.2kg (±2.3kg), respectively). At the end of the experimental protocol (i.e. week 37) the difference in terms of body mass between control and groups B and C appears to crystallise (average (±STDEV) body mass for groups A, B and C is equal to 27.5kg (±1.4kg) 32.0kg (±3.0kg) and 31.8kg (±3.5kg) respectively). Moreover, groups B and C also have significantly higher levels of T-CHOL compared to control. At the end of the protocol, group C also appears to have significantly higher levels of TG compared to the other two groups (Fig. 3). At this point it should be highlighted that group C was exposed to exercise only during the last nine weeks of the experi- mental protocol (i.e. weeks 28-37). Therefore any difference between groups B and C that is observed during the 28 th week of the experimental protocol (or earlier than that) cannot be attributed to exercise (Fig. 3). One way repeated measures ANOVA for group C before and after the introduction of exercise showed statistically signi- ficant: A