Retention of improvement in gait stability over 14 weeks due to trip-perturbation training is dependent on perturbation dose

© 2018 Elsevier Ltd Perturbation training is an emerging approach to reduce fall risk in the elderly. This study examined potential differences in retention of improvements in reactive gait stability over 14 weeks resulting from unexpected trip-like gait perturbations. Twenty-four healthy middle-aged adults (41–62 years) were assigned randomly to either a single perturbation group (SINGLE, n = 9) or a group subjected to eight trip-like gait perturbations (MULTIPLE, n = 15). While participants walked on a treadmill a custom-built brake-and-release system was used to unexpectedly apply resistance during swing phase to the lower right limb via an ankle strap. The anteroposterior margin of stability (MoS) was calculated as the difference between the anterior boundary of the base of support and the extrapolated centre of mass at foot touchdown for the perturbed step and the first recovery step during the first and second (MULTIPLE group only) perturbation trials for the initial walking session and retention-test walking 14 weeks later. Group MULTIPLE retained the improvements in reactive gait stability to the perturbations (increased MoS at touchdown for perturbed and first recovery steps; p < 0.01). However, in group SINGLE no differences in MoS were detected after 14 weeks compared to the initial walking session. These findings provide evidence for the requirement of a threshold trip-perturbation dose if adaptive changes in the human neuromotor system over several months, aimed at the improvement in fall-resisting skills, are to occur

Fitness &amp; Sports Medicine

Background and Objectives: A variety of training methods has developed within hypoxic training. The continuous live low-train high method offers simple usability, but effects on endurance capacity are still almost empirically unproven. To clarify whether the continuous live low-train high method has positive effects on the body, it seems worthwhile to collectexploratively the most frequently studied variables and analyzethem for similarities.Methods: A systematic review was conducted to examine the literature onthe continuous live low-train high method for the most frequently-tested variables of endurance capacity. Studies which examined continuous endurance training in normobaric hypoxia from the earliest records up to June 2019 were included.Results: Twelve studies met the criteria and were analyzed. Oxygen uptake at the second ventilatory threshold tested in normoxia exhibits significant changes in six studies through hypoxic training, whereas the changes due to normoxic training are mostly non-significant. The remaining ventilatory, hematological and performance-related variables show only partially significant changes and cannot demonstrate differences between hypoxic and normoxic training.Discussion: The consideration of the variables revealed similarities in the oxygen uptake at the second ventilatory threshold, but a clear detection of differences between hypoxic continuous live low-train high and normoxic training was not possible. This review offers an overview of already-examined variables and recommends additional consideration of submaximal variables of endurance capacity in study designs.KEY WORDS: Altitude, Hypoxia, Hypoxic Training, Continuous , Cardiopulmonar

Transgenic and knock out mice in skeletal research. Towards a molecular understanding of the mammalian skeleton.

Our understanding of the biology of the skeleton, like that of virtually every other subject in biology, has been transformed by recent advances in human and mouse genetics. Among mammals, mice are the most promising animals for this experimental work. Because extensive genetic information exists, many mouse mutations are known, and cells from early mouse developmental stages are accessible, scientists have developed transgenic mice - mice in which a gene is introduced or ablated in the germ line. Thus far, we have analyzed more than 100 different transgenic and knock out models with various skeletal phenotypes, covering the major aspects of both skeletal development and skeletal maintenance. Based on these results we here present a first perspective on transgenic and gene knock out animals in skeletal research, including insights in signaling pathways controlling endochondral bone formation, in the regulation of osteoblast function, osteoclastic bone resorption and in bone tumorigenesis, as well as the central control of bone formation. The use of transgenic mice to dissect and analyze regulatory mechanisms in bone cell physiology and the pathogenesis of human bone diseases is an extremely powerful experimental tool. The data presented here demonstrate that the successful convergence of novel genetic approaches with the established and fundamental knowledge of bone biology has made a beginning