The objective of this study was to examine the content validity of commonly used muscle performance tests in military personnel and to investigate the reliability of a proposed test battery. For the content validity investigation, thirty selected tests were those described in the literature and/or commonly used in the Nordic and North Atlantic Treaty Organization (NATO) countries. Nine selected experts rated, on a four-point Likert scale, the relevance of these tests in relation to five different work tasks: lifting, carrying equipment on the body or in the hands, climbing, and digging. Thereafter, a content validity index (CVI) was calculated for each work task. The result showed excellent CVI (≥0.78) for sixteen tests, which comprised of one or more of the military work tasks. Three of the tests; the functional lower-limb loading test (the Ranger test), dead-lift with kettlebells, and back extension, showed excellent content validity for four of the work tasks. For the development of a new muscle strength/endurance test battery, these three tests were further supplemented with two other tests, namely, the chins and side-bridge test. The inter-rater reliability was high (intraclass correlation coefficient, ICC2,1 0.99) for all five tests. The intra-rater reliability was good to high (ICC3,1 0.82–0.96) with an acceptable standard error of mean (SEM), except for the side-bridge test (SEM%>15). Thus, the final suggested test battery for a valid and reliable evaluation of soldiers’ muscle performance comprised the following four tests; the Ranger test, dead-lift with kettlebells, chins, and back extension test. The criterion-related validity of the test battery should be further evaluated for soldiers exposed to varying physical workload.

Background: CD47 and its receptor SIRP␣ are suggested to regulate bone metabolism. Results: Lack of CD47 prevents stromal cell SIRP␣ signaling, which impairs bone marrow stromal cell differentiation, subsequent osteoclast differentiation, and bone homeostasis. Conclusion: CD47 and SIRP␣ both mediate normal bone cell and bone tissue formation. Significance: CD47/SIRP␣ may be a future molecular target to modulate bone homeostasis.

Background and objectivesThe authors have previously reported that the cysteine proteinase inhibitor (CPI) cystatin C (CysC) reduces osteoclast formation induced by signal pathways activated by either PTH receptor, vitamin D receptor or gp130 in crude mouse bone marrow cultures (ref). In the present study, the authors have investigated if CysC, E-64 (fungal CPI) and the tetrapeptidyl derivative Z-RLVG-CHN 2 (representing Arg 8 -Leu 9 -Val 10 -Gly 11 of the aminoterminal end of CysC) can inhibit osteoclast formation using purifi ed mouse and human osteoclast progenitors stimulated by either RANKL or LPS Escherichia coli. Results All three inhibitors concentration-dependently (IC 50 CysC=0.3 μM, E-64=3μM, Z-RLVG-CHN 2 =0.3 μM) inhibited RANKL induced osteoclast formation in mouse bone marrow macrophage (BMM) cultures; similar observations were made using human peripheral blood CD14 + progenitors. These data were based upon (1) counting the number of TRAP + osteoclasts in cultures on plastic or (2) on bone, (3) assessing actin-ring expressing cells and (4) by analysing pit formation and release of CTX when progenitor cells were cultured on bone. The effect was induced early during differentiation as demonstrated by withdrawal and addition of CysC at different time points, by showing that a variety of RANKL induced osteoclastic genes (Calcr, Acp5, Ctsk, Integrin b3, were downregulated and that BMM was maintained at a macrophage stage (capacity to phagocytose and increased Irf-8). The inhibitory effect was associated with decreased mRNA and protein expression of c-Fos and Nfatc1, and with decreased activation of NF-κB. Inhibition was also associated with decreased mRNA and protein expression of