Even if exercise by resistance training can offer several health benefits and increase muscle strength, our findings argue against recommending the increasingly popular exercise by resistance training to the younger population for the purpose of improving bone health. The majority of HM781-36B mw subjects in the resistance

training group were exercising at a recreational level, while subjects in soccer-playing group were training at a competitive level. This may explain the higher lean mass (although this difference was not significant) among soccer players compared to the resistance training men. There are some limitations of the present study. The cross-sectional design does not allow for direct cause–effect relationships to be established. For this, it would be necessary to conduct a randomized controlled trial. It Evofosfamide is OSI-906 nmr possible that differences in bone variables may be due also to genetics and self-selection into sports. For example, individuals with genetically favorable musculature and skeleton may tend to be more successful in certain sports and, therefore, participate to a higher extent. However, we could not find any difference in body size parameters (height or weight) between subjects who had been active in sport activity and nonathletic subjects. Although this argues against a problem with

selection bias, it cannot be ruled Ibrutinib supplier out that this is the cause of the associations found. A methodological limitation is that the bone structure parameters presented in this study have been obtained from 3D pQCT measurements and are thus density-based. This means, for example, that a trabecula or a cortex with higher bone density will be measured as having a greater thickness than a corresponding bone of the same actual thickness but with a lower density. Furthermore, the results from the present study derive from investigations of men aged 23–25 years and may not be applicable to other age groups. Present

and former physical activity habits were assessed using a retrospective self-reporting questionnaire, which may have been subject to a limited ability of the subjects to recall their history of physical activity, and this effect may have caused bias and misclassification. However, by using a standardized self-administered questionnaire, based on a validated physical activity questionnaire [34], with amended questions concerning physical activity habits over the whole year, we believe that we have been able to collect accurate information about physical activity habits. Furthermore, some studies have reported that people can recall activity patterns from up to 10 years in the past with high reliability and that recall of more vigorous activity, such as sports and exercise, is more accurate than recall of less intensive activities [47, 48].