The Effects of Endurance Running Training on Young Adult Bone: Densitometry vs. Biomaterial Properties

Densitometric measurement of bone mineral parameters has been developed in recent decades. Since bone strength is associated with bone mineral density (BMD) and/or bone mineral content (BMC), densitometric measurement is widely accepted and used as one golden standard in clinical settings to determine bone health. Based on this concept, some human studies have suggested that endurance training, such as long distance running, provides no benefit and may even be harmful to bone health or bone mineral accretion during development, since long distance runners often have low BMD and/or BMC and may even exhibit conditions associated with bone loss or osteopenia.1, 2 Conversely, serum bone marker assays in healthy distance runners show normal or positive bone metabolism status.3, 4 Therefore, the definite role of endurance running training (ERT) on bone health remains a controversial issue. It would be valuable to further clarify whether ERT benefits bone health through a pathway other than absolutely increasing BMD or BMC. Clinical observations of human subjects require further basic studies to investigate possible mechanisms. Animal studies can provide unique ways not feasible in studies using human subjects of assessing the effects of endurance running on bone. Generally, previous animal studies further verified benefits of ERT to bone health. However, the limitations of animal studies must be clarified before applying their findings to human beings. The present article reviews the phenomena shown in bone of adolescent or young adult distance runners. Moreover, previous animal studies which adopted growing and young adult rats as subjects are reviewed, and the applicability of the findings to humans is also discussed

Association analysis of ACE and ACTN3 in Elite Caucasian and East Asian Swimmers

PURPOSE: Polymorphic variation in the angiotensin-converting enzyme (ACE) and alpha-actinin-3 (ACTN3) genes has been reported to be associated with endurance and/or power-related human performance. Our aim was to investigate whether polymorphisms in ACE and ACTN3 are associated with elite swimmer status in Caucasian and East Asian populations. METHODS: ACE I/D and ACTN3 R577X genotyping was carried out for 200 elite Caucasian swimmers from European, Commonwealth, Russian and American cohorts (short and middle distance, SMD ≤ 400 m, n = 130; long distance, LD greater than 400 m, n = 70) and 326 elite Japanese and Taiwanese swimmers (short distance, SD ≤ 100 m, n = 166; middle distance, MD: 200 - 400 m, n = 160). Genetic associations were evaluated by logistic regression and other tests accommodating multiple testing adjustment. RESULTS: ACE I/D was associated with swimmer status in Caucasians, with the D-allele being overrepresented in SMD swimmers under both additive and I-allele dominant models (permutation test p = 0.003 and p = 0.0005, respectively). ACE I/D was also associated with swimmer status in East Asians. In this group, however, the I-allele was overrepresented in the SD swimmer group (permutation test p = 0.041 and p = 0.0098 under the additive and the D-allele-dominant models, respectively). ACTN3 R577X was not significantly associated with swimmer status in either Caucasians or East Asians. CONCLUSIONS: ACE I/D associations were observed in these elite swimmer cohorts, with different risk alleles responsible for the associations in swimmers of different ethnicities. The functional ACTN3 R577X polymorphism did not show any significant association with elite swimmer status, despite numerous previous reports of associations with 'power/sprint' performance in other sports.Additional co-authors: Jason Gulbin, Viktor A. Rogozkin, Ildus I. Ahmetov, Nan Yang, Kathryn N. North, Saraslanidis Ploutarhos, Hugh E. Montgomery, Mark E.S. Bailey, and Yannis P. Pitsiladi

The effects of repeated maximal voluntary isokinetic eccentric exercise on recovery from muscle damage

Même si ces exercices répétés 3 ou 6 jours après l'exercice initial n'augmentent pas le dommage musculaire et la douleur musculaire ni n'influencent la récupération, le travail musculaire total est sensiblement réduit