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Daniel Hamacher, Dennis Hamacher, Roy Müller, Lutz Schega, and Astrid Zech

The aim of the current study was to evaluate the effect of a cognitive dual task on minimum toe clearance (MTC) variability while walking. In a randomized cross-over design, gait kinematics of 25 older (70 ± 6 years) and 45 younger adults (25 ± 2 years) were captured during normal walking and dual-task walking. Variability of stride time, stride length, and MTC were calculated. Differences between normal versus dual-task walking were assessed using Wilcoxon tests. Compared with normal walking, dual-task walking caused an increase in stride time variability (older adults: p < .001 and younger adults: p < .001), while the variability of MTC decreased (older adults: p = .032 and younger adults: p = .012). MTC seems to be a task-relevant gait parameter that is controlled with high priority to preserve its variability under challenging conditions.

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Dennis Hamacher, Daniel Hamacher, Kathrin Rehfeld, Anita Hökelmann, and Lutz Schega

Dancing is a complex sensorimotor activity involving physical and mental elements which have positive effects on cognitive functions and motor control. The present randomized controlled trial aims to analyze the effects of a dancing program on the performance on a motorcognitive dual task. Data of 35 older adults, who were assigned to a dancing group or a health-related exercise group, are presented in the study. In pretest and posttest, we assessed cognitive performance and variability of minimum foot clearance, stride time, and stride length while walking. Regarding the cognitive performance and the stride-to-stride variability of minimum foot clearance, interaction effects have been found, indicating that dancing lowers gait variability to a higher extent than conventional health-related exercise. The data show that dancing improves minimum foot clearance variability and cognitive performance in a dual-task situation. Multi-task exercises (like dancing) might be a powerful tool to improve motor-cognitive dual-task performance.

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Alexander Törpel, Tim Becker, Angelina Thiers, Dennis Hamacher, and Lutz Schega

Context:The use of isokinetic dynamometers playing an important role in different settings of sports and medicine. Therefore, a high reliability of these devices is required. Objective: The aim of this study was to examine the intersession reliability of the dynamometer BTE PrimusRS regarding to the isolated single-joint exercises extension/flexion of the knee and elbow for isokinetic testing. Design: Intersession reliability. Setting: Clinical settings and sports science. Participants: 16 young male students. Intervention: The testing protocol includes 5 consecutive repetitions (concentric/concentric) at a velocity of 60°/s for the exercises. Main Outcome Measures: Raw data of torque curves were used to determine the peak torque. Reliability was evaluated with the intraclass correlation coefficient (ICC), the limits of agreement (LoA), and the bias and the variability of measurements (V). Results: High ICC values (.954-.991) were found for the used exercises. However, the LoAs yielded up to over 16 Nm and the V yielded up to nearly 9 % in several testing exercises, indicating poor absolute reliability. Conclusion: The BTE PrimusRS shows good to excellent reliability. However, regarding the absolute measures of reliability, the users must decide as experts in their fields whether this reliability is sufficient for their purposes.