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Aspects of Ergonomics in the Use of Respiratory Protective Devices
Published in Katarzyna Majchrzycka, Nanoaerosols, Air Filtering and Respiratory Protection, 2020
Breathing requires the use of muscles of respiration, which, like any muscles, consume energy. In order to force breathing, it is necessary to overcome mechanical properties of lungs, including elastic lung resistance, frictional resistance occurring during lung and chest movements, and resistance of bronchial tree flow. This work is known as the work of breathing (Cabello and Mandcebo 2009; Love et al. 1977). Changes in the mechanical properties of lungs and/or chest accompanied by or as a result of disease may increase the work of breathing. The muscles of respiration must then do more work over long periods. In such situations, as with other skeletal muscles, muscle fatigue and respiratory failure may occur.
Acceleration
Published in David G. Newman, Flying Fast Jets, 2014
+Gz also increases the physical work of breathing. The +Gz acceleration forces the diaphragm and abdominal contents downward, and the chest wall becomes proportionally heavier, requiring more effort. At higher levels, the work of breathing increases due to reduced lung compliance. An increase in respiratory work of some 55 per cent at +3 Gz has been reported. At +5 Gz, total lung capacity is reduced by approximately 15 per cent.
Wearing body armour and backpack loads increase the likelihood of expiratory flow limitation and respiratory muscle fatigue during marching
Published in Ergonomics, 2019
Nicola C. D. Armstrong, Amanda Ward, Mitch Lomax, Michael J. Tipton, James R. House
During the current study, O2 and E increased with mass carried and exercise intensity (Table 4). These additional ventilatory requirements were met by increases in ƒb rather than VT leading to a rapid and shallow breathing pattern (Table 4). A concomitant rise in E/CO2 and reduction in PETCO2 was also present during very heavy exercise in the heaviest loads which is indicative of hyperventilation (Table 4). This inefficient pattern of breathing will have increased work of breathing and contributed to the observed respiratory muscle fatigue.
Inspiratory muscle training at sea level improves the strength of inspiratory muscles during load carriage in cold-hypoxia
Published in Ergonomics, 2020
K. L. Hinde, C. Low, R. Lloyd, C. B. Cooke
Inspiratory muscle training significantly increased Pimax in the training group when compared to pre-intervention values and the control group. Increases in inspiratory muscle strength have been attributed to increased muscle hypertrophy, increased motor unit recruitment and/or neural adaptations (Kellerman, Martin, and Davenport 2000; Ramírez-Sarmiento et al. 2002) which reduce the relative intensity of inspiratory work reducing the work of breathing (Ray, Pendergast, and Lundgren 2010). Following very similar IMT programmes and performing exercise in hypoxia, other studies have shown increases in Pimax comparable to the present study [24.5% by (Downey et al. 2007), 28.4% by (Salazar-Martinez et al. 2017) and ∼13.5% by (Lomax, Massey, and House 2017)]. In addition, post-hoc power calculations (G*Power) using Pimax results (ηp2 = 0.302) showed a power of 0.99 implying the study was sufficiently powered. Although IMTF resulted in greater Pimax when compared to pre-intervention, Pimax was not significantly different to post-IMT values, thus did not have any additional effect. Similar findings were reported by Tong et al. (2016) who found that while performance in the sport-specific endurance plank test improved in the intervention group, Pimax did not increase any further when compared to post-IMT values. Similarly, Faghy and Brown (2019) reported Pimax to be unchanged post-IMTF when compared to post-IMT values. The main differences between that of the present study and Faghy and Brown (2019) are the exercises used in IMTF as they were focussed on core muscle training specific to running rather than load carriage and furthermore, despite no further increase in Pimax following IMTF, they reported an increase in performance on a loaded 2.4km time-trial. A time-trial was not used to assess performance in the present study because this would have impaired ecological validity as it is not relevant to a recreational, mountaineering population. Therefore, the IMTF used in this study is unlikely to bring any further physiological benefits to prolonged sub-maximal load carriage that IMT does not already provide. Faghy and Brown (2019) suggested that no change in Pimax following IMTF may be due to the reduction in training volume when changing from IMT to IMTF, as training reduced from every day to three times a week. Despite maintaining training intensity during IMTF at 50%Pimax, which with an increasing baseline Pimax meant that intensity progressively increased, this constant inspiratory load may have contributed to no further significant improvement in Pimax post-IMTF.