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In recent years, climbing sports is on the rise making its Olympic debut in 2021. Physiological traits of professional rock climbers have been intensively studied, while recreational indoor climbers are less investigated, especially regarding grip strength and upper extremity proportions. In this cross-sectional study, we aimed to understand what discerns the recreational climber from disparate recreational athletes. Therefore, we analyzed 50 recreational climbing (30.3 &plusmn, 12.7 years, 1.76 &plusmn, 0.09 m and 67.0 &plusmn, 14.0 kg) and 50 non-climbing athletes (26.4 &plusmn, 9.1 years, 1.78 &plusmn, 0.09 m and 73.2 &plusmn, 12.6 kg) to detect differences in their finger grip strength of seven different pinches. In addition, the upper extremity proportions were measured. Even in recreational climbers, almost all analyzed grips were stronger compared to other athletes (p &lt, 0.05 in all but non-dominant fist, small to moderate effect sizes). Only the grip strength of the whole non-dominant hand was not significantly different (p = 0.17). Interestingly, differences between the dominant and non-dominant hand appeared to be larger in the non-climbing (all p &lt, 0.05, all but one with small effect size) compared to the climbing cohort (pinch I/IV and pinch I/II+III+IV not different and mostly trivial). Circumference measurements showed that 10 cm below the lateral epicondyle, climbers exhibited significantly greater perimeter compared to non-climbing athletes (p &lt, 0.05, small effect size). Our results show that recreational climbers have higher measured grip strength, but less profound differences between the dominant and non-dominant hand.

In patients with osteomalacia, a defect in bone mineralization leads to changed char- acteristics of the bone surface. Considering that the properties of the surrounding matrix influence function and differentiation of cells, we aimed to investigate the ef- fect of osteoidosis on differentiation and function of osteoclasts. Based on osteoma- lacic bone biopsies, a model for osteoidosis in vitro (OIV) was established. Peripheral blood mononuclear cells were differentiated to osteoclasts on mineralized surfaces (MS) as internal control and on OIV. We observed a significantly reduced number of osteoclasts and surface resorption on OIV. Atomic force microscopy revealed a significant effect of the altered degree of mineralization on surface mechanics and an unmasking of collagen fibres on the surface. Indeed, coating of MS with RGD peptides mimicked the resorption phenotype observed in OIV, suggesting that the altered differentiation of osteoclasts on OIV might be associated with an interaction of the cells with amino acid sequences of unmasked extracellular matrix proteins containing RGD sequences. Transcriptome analysis uncovered a strong significant up-regulation of transmembrane glycoprotein TROP2 in osteoclastic cultures on OIV. TROP2 expression on OIV was also confirmed on the protein level and found on the bone surface of patients with osteomalacia. Taken together, our results show a direct influence of the mineralization state of the extracellular matrix surface on dif- ferentiation and function of osteoclasts on this surface which may be important for the pathophysiology of osteomalacia and other bone disorders with changed ratio of osteoid to bone. Open-Access-Publikationsfonds 2020 peerReviewed

Introduction: The “Brocken challenge” ultramarathon takes place in the cold of February over 80 km with 1,900 m of elevation change. The purpose of this study was to evaluate the effects of an ultramarathon under extreme conditions on the lower extremities. Methods: Out of the 182 starters, 44 athletes were included into the study (n=44). We examined these athletes using a questionnaire, by measuring circumferences of their lower extremities and by standardized sonographic measurement of joint effusion of knee and ankle joints before and after the run. Results: After the run, the right leg and both feet significantly increased in circumference. Knee joints on both sides and the left ankle joint showed significantly more effusion after the run (right knee: 84%, right ankle: 43%; left knee: 80%, left ankle: 48%). Heavier and less trained athletes showed significantly more effusion in sonographic assessment of the knee and ankle. Neither swelling, nor effusion had a measurable influence on finishing time. Conclusions: Running an ultramarathon in the cold overloads the fluid draining capacity in the muscles and joints of the legs especially in heavier and less trained athletes without measurable immediate effect on performance. Open-Access-Publikationsfonds 2019 peerReviewed