Instability Resistance Training Decreases Motor Noise During Challenging Walking Tasks in Older Adults: A 10-Week Double-Blinded RCT

Locomotor stability is challenged by internal perturbations, e.g., motor noise, and external perturbations, e.g., changes in surface compliance. One means to compensate for such perturbations is to employ motor synergies, defined here as co-variation among a set of elements that acts to stabilize, or provide similar trial-to-trial (or step-to-step) output, even in the presence of small variations in initial conditions. Whereas evidence exists that synergies related to the upper extremities can be trained, the extent to which lower limb synergies, such as those which may be needed to successfully locomote in complex environments, remains unknown. The purpose of this study was to evaluate if resistance training (RT) in unstable environments could promote coordination patterns associated with stronger synergies during gait. Sixty-eight participants between the age of 65 and 80 were randomly assigned to one of three different RT modalities: stable whole-limb machine-based RT (S-MRT), instability free-weight RT (I-FRT), and stable machine-based adductor/abductor RT (S-MRTHIP). Before and after RT, participants walked across an even lab floor and a more challenging uneven surface with and without holding a weighted bag. The uncontrolled manifold control analysis (UCM) was used to calculate the synergy index (i.e., strength of the kinematic synergy) related to stabilization of our performance variable, the mediolateral trajectory of the swing foot, under each condition. Regardless of RT group, there was no effect of RT on the synergy index when walking across the even lab floor. However, the synergy index during the two uneven surface conditions was stronger after I-FRT but was not affected by the other RT modalities. The stronger synergy index for the I-FRT group was due to improved coordination as quantified by an overall increase in variability in elemental variable space but a decrease in the variability that negatively affects performance. The unstable environment offered by I-FRT allows for exploration of motor solutions in a manner that appears to transfer to challenging locomotor tasks. Introducing tasks that promote, rather than limit, exploration of motor solutions seems to be a valuable exercise modality to strengthen kinematic synergies that cannot be achieved with traditional strengthening paradigms (e.g., S-MRT).Clinical Trial Registration:www.ClinicalTrials.gov, identifier NCT03017365

Weight estimations with time-reversed point-light displays

Interpreting other’s actions is a very important ability not only in social life, but also in interactive sports. Previous experiments have demonstrated good estimation performances for the weight of lifted objects through point-light displays. The basis for these performances is commonly assigned to the concept of motor simulation regarding observed actions. In this study, we investigated the weak version of the motor simulation hypothesis which claims that the goal of an observed action strongly influences its understanding (Fogassi, Ferrari, Gesierich, Rozzi, Chersi, & Rizzolatti, 2005). Therefore, we conducted a weight judgement task with point-light displays and showed participants videos of a model lifting and lowering three different weights. The experimental manipulation consisted of a goal change of these actions by showing the videos normal and in a time-reversed order of sequence. The results show a systematic overestimation of weights for time-reversed lowering actions (thus looking like lifting actions) while weight estimations for time-reversed lifting actions did not differ from the original playback direction. The results are discussed in terms of motor simulation and different kinematic profiles of the presented actions. © 2020, The Author(s)

TENNIS GROUND STROKES FROM A BIRD’S EYE VIEW - A ESTIMATE OF ANGULAR MOMENTUM ABOUT THE LONGITUDINAL BODY AXIS

In this paper, a simple 2D video method will be outlined to estimate the angular momentum about the longitudinal body axis in tennis ground strokes from the base line. From a bird’s eye view, ground strokes of 19 young male experienced tennis players with two different skill levels were analyzed when returning balls released from a ball machine with three different ball frequencies. The angle between the shoulder axis and the base line was used as an estimate for the angular momentum about the longitudinal body axis. A validation procedure with a fully automated 3D motion capture system as adopted to evaluate the error involved in the 2D motion analysis. The results of this study show that for forehand and backhand strokes advanced young tennis players show consistently larger shoulder-baseline angles across all ball frequencies than players with a lower skill level

The Relationship Between Cognition and Sensorimotor Behavior in an F1 Driving Simulation: An Explorative Study

Sensorimotor control simultaneously engages multiple cognitive processes, like decision making, intention, processing, and the integration of multisensory signals. The reciprocal relationship of cognition and sensorimotor learning is well documented. However, little is known if the status of cognitive skills relates to immediate sensorimotor performance of performing a novel skill. Thus, we aim to explore whether cognitive skills in general and executive functions (EFs) in particular may relate to novel sensorimotor performance and adaptive skills. Therefore, 23 male participants engaged in a novel driving simulation for 2 days. On the first day, they accustomed to the F1 simulation until meeting a preset threshold (adaption). On the second day, they aimed to drive as fast as possible (performance). In addition, we measured EFs and global cognition. We found meaningful relationships between response inhibition (Stroop Color and Word Test), the driving performance (r = 0.48, p = 0.013), and the adaptive ability (r = 0.34, p = 0.012). All other tests of executive functioning and global cognition remained non-significant. Our results illustrate an association of driving performance and adaptive abilities and the EF selective attention/inhibition in a novel F1 simulation. Given the novelty of the task, the ability to adjust sensorimotor behavior to keep the car on the track seems to be the primary necessary skill to navigate the lap and achieve fast times. © Copyright © 2020 Eckardt, Roden, Grube and Schorer

SQUATS PERFORMED ON AN UNSTABLE SURFACE ELICIT HIGHER TRANSVERSAL FORCE OUTPUT COMPARED TO MORE STABLE SQUATS

Instability resistance training (RT) or exercising within an unstable environment is a popular training modality and frequently used in training, rehabilitation and prevention settings. Yet, due to the reported reduced force output during exercising within unstable condition, instability RT is said to lack the necessary overload to induce meaningful effects. However, empirical evidence of interventions suggests otherwise. The aim of this study was to systematically analyse instability RT vs. stable RT and discuss potential mechanisms. Therefore, we analysed squats within unstable and stable environments and calculated transversal and vertical forces. Greater transversal plane ground reaction forces were observed while performing squats on the unstable surface (p = .013; d = 1.88, CI-95% [0.33, 3.39]). In contrast, vertical force output remained similar for both conditions (p = .764; d = 0.14, CI-95% [-0.77, 1.02])

KINEMATIC STRATEGIES TO KEEP AN UNCHANGED MARGIN OF STABILITY DURING TREADMILL RUNNING ON AN EVEN AND UNEVEN SURFACE

Understanding how to control stability when running, particularly when being exposed to uneven terrain, is vital to prevent falls and to get an insight into compensatory strategies while running on uneven terrain. The purpose of this study was to assess surface related differences of the margin of stability, kinematics of hip and knee and upper body acceleration which may affect the control of running stability. Eighteen healthy younger adults ran on an even and an uneven surfaced treadmill for two minutes at fixed speeds of 2.0 m/s (female) and 2.2 m/s (male), respectively. Results showed an unchanged margin of stability in both conditions. Further, lower limb kinematics, step width variability and upper body acceleration increased on the uneven surface meaningfully to keep the extrapolated centre of mass within the base of support

Effect of neoadjuvant chemoradiation and postoperative radiotherapy on expression of heat shock protein 70 (HSP70) in head and neck vessels

<p>Abstract</p> <p>Background</p> <p>Preoperative radiotherapy and chemotherapy in patients with head and neck cancer result in changes to the vessels that are used to construct microsurgical anastomoses. The aim of the study was to investigate quantitative changes and HSP70 expression of irradiated neck recipient vessels and transplant vessels used for microsurgical anastomoses.</p> <p>Methods</p> <p>Of 20 patients included in this study five patients received neoadjuvant chemoradiation, another five received conventional radiotherapy and 10 patients where treated without previous radiotherapy. During surgical procedure, vessel specimens where obtained by the surgeon. Immunhistochemical staining of HSP70 was performed and quantitative measurement and evaluation of HSP70 was carried out.</p> <p>Results</p> <p>Conventional radiation and neoadjuvant chemoradiation revealed in a thickening of the intima layer of recipient vessels. A increased expression of HSP70 could be detected in the media layer of the recipient veins as well as in the transplant veins of patients treated with neoadjuvant chemoradiation. Radiation and chemoradiation decreased the HSP70 expression of the intima layer in recipient arteries. Conventional radiation led to a decrease of HSP70 expression in the media layer of recipient arteries.</p> <p>Conclusion</p> <p>Our results showed that anticancer drugs can lead to a thickening of the intima layer of transplant and recipient veins and also increase the HSP70 expression in the media layer of the recipient vessels. In contrast, conventional radiation decreased the HSP70 expression in the intima layer of arteries and the media layer of recipient arteries and veins. Comparing these results with wall thickness, it was concluded, that high levels of HSP70 may prevent the intima layer of arteries and the media layer of vein from thickening.</p

Reconstruction of defects of maxillary sinus wall after removal of a huge odontogenic lesion using prebended 3D titanium-mesh and CAD/CAM technique

A 63 year-old male with a huge odontogenic lesion of sinus maxillaris was treated with computer-assisted surgery. After resection of the odontogenic lesion, the sinus wall was reconstructed with a prebended 3D titanium-mesh using CAD/CAM technique. This work provides a new treatment device for maxillary reconstruction via rapid prototyping procedures