China
Africa
Explore chapters and articles related to this topic
Differences in Physiology, Biomechanics and Motor Control of Walking With Backpack Loads Between Children and Adults
Published in Youlian Hong, Routledge Handbook of Ergonomics in Sport and Exercise, 2013
Backpack loads increase the height of the combined centre of mass (COM) of the body and backpack system and thereby induce instability for standing as well as walking conditions. DST has been used as a measure of gait stability in the sagittal plane (Charteris, 1998; Hong and Brueggemann, 2000; McGraw et al., 2000). Walking velocity has also been associated with gait stability and it has been suggested that a lower walking velocity is a consequence of induced gait instability due to higher COM (Dingwell and Marin, 2006; England and Granata, 2007). Other parameters that have been reported to change during load carriage are stride length (SL, cm) and stride frequency (SF, steps per minute). It should be noted that the walking speed is a product of SL and SF.
Deflection of Beams
Published in Robert L. Mott, Joseph A. Untener, Applied Strength of Materials, Sixth Edition SI Units Version, 2017
Robert L. Mott, Joseph A. Untener
But is beam deflection always bad? Would it be good to have diving board that didn’t flex at all under load? Think about the plastic snaps that are likely used as buckles on your backpack. The plastic extensions on those are small beams, and if they do not have the correct properties in terms of bending, they would not snap and unsnap very well at all.
Deflection of Beams
Published in Robert L. Mott, Joseph A. Untener, Applied Strength of Materials, 2016
Robert L. Mott, Joseph A. Untener
But is beam deflection always bad? Would it be good to have diving board that didn’t flex at all under load? Think about the plastic snaps that are likely used as buckles on your backpack. The plastic extensions on those are small beams, and if they do not have the correct properties in terms of bending, they would not snap and unsnap very well at all.
Gait and neuromuscular dynamics during level and uphill walking carrying military loads
Published in European Journal of Sport Science, 2022
Gregory S. Walsh, Isabel Harrison
Greater EMGMEAN was also found in both loaded conditions compared to unloaded walking for the TRAP, RF and GM and in webbing for ES. These findings are in accordance with previous findings (Lindner et al., 2012; Paul et al., 2016; Rice et al., 2017; Sessoms et al., 2020). Greater activity is indicative of the need to overcome the added inertia for vertical and forward propulsion (i.e. RF and GM activity), additional support for the trunk (i.e. ES activity) and to support the shoulder girdle (i.e. TRAP activity). The greater EMGMEAN of multiple muscles in the loaded walking conditions indicates the greater neuromuscular demand in these conditions. This greater demand may explain the decreased dynamic stability of muscle activations as the CNS attempts to accommodate the additional demand. The EMGMEAN of ES was only greater in webbing but not backpack conditions. A large inter-subject variability was found in ES activity in backpack conditions. It is possible that despite efforts to avoid interference of the load on the EMG recording and subsequent visual inspection of the data that this variability was the result of artefacts caused by the load. Contrary to the expected outcomes, RA activity was not increased by load carriage. This was likely the result of the substantial inter-subject variability demonstrated for this muscle.
Effects of backpack weight on the performance of basic short-term/working memory tasks during flat-surface standing
Published in Ergonomics, 2019
Minseok Son, Soomin Hyun, Donghyun Beck, Jaemoon Jung, Woojin Park
The physical task was quiet standing with loaded backpack and was common to all three experiment tasks. Backpack weight (representing external weight) was the independent variable of the study and had four levels in relation to the body weight (0, 15, 25 and 40% of body weight, denoted as BW 0, BW 15, BW 25 and BW 40, respectively). The four backpack weight levels for each participant were generated by placing different combinations of weight plates (1, 1.5, 3, 5 and 10 kg weights) into a backpack. Figure 1 visually depicts the backpack used in this study. The weight plates were fixed inside the backpack using a pole and Styrofoam (polystyrene). The design of the backpack allowed the centre of mass of the backpack to remain at a fixed position in the transverse plane across four different backpack weight levels. The participant stood on top of a Bertec force plate (model 4060, Bertec Corporation, Columbus, USA), in balance, for 15 s. Participants were instructed to complete this task in a comfortable stance, and with both feet fixed on the force plate.