Effect of carrying a weighted backpack on lung mechanics during treadmill walking in healthy men

• Published in: European journal of applied physiology Vol. 112; no. 6; pp. 2001 - 2012
• Main Authors: Dominelli, Paolo B., Sheel, A. William, Foster, Glen E.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer-Verlag 01.06.2012; Springer; Springer Nature B.V
• Subjects: Adult; Backpacks; Biological and medical sciences; Biomedical and Life Sciences; Biomedicine; Catheters; Exercise; Exercise - physiology; Exercise Test - methods; Fitness equipment; Forced Expiratory Volume - physiology; Fundamental and applied biological sciences. Psychology; Human Physiology; Humans; Lung - physiology; Lung Volume Measurements - methods; Male; Maximal Expiratory Flow-Volume Curves - physiology; Mechanics; Occupational Medicine/Industrial Medicine; Original Article; Peak Expiratory Flow Rate - physiology; Physical fitness; Resistance Training - methods; Respiratory Mechanics - physiology; Sports Medicine; Ventilation; Ventilation - methods; Vertebrates: body movement. Posture. Locomotion. Flight. Swimming. Physical exercise. Rest. Sports; Vital Capacity - physiology; Walking - physiology; Weight-Bearing; Young Adult; Canada; Backpack; Lung volumes; Ventilatory capacity; Work of breathing; Pulmonary mechanics; Human; Lung volume; Locomotion; Walking; Lung; Respiration; Respiratory system
• ISSN: 1439-6319; 1439-6327; 1439-6327
• DOI: 10.1007/s00421-011-2177-8

Weighted backpacks are used extensively in recreational and occupational settings, yet their effects on lung mechanics during acute exercise is poorly understood. The purpose of this study was to determine the effects of different backpack weights on lung mechanics and breathing patterns during treadmill walking. Subjects ( n  = 7, age = 28 ± 6 years), completed two 2.5-min exercise stages for each backpack condition [no backpack (NP), an un-weighted backpack (NW) or a backpack weighing 15, 25 or 35 kg]. A maximal expiratory flow volume curve was generated for each backpack condition and an oesophageal balloon catheter was used to estimate pleural pressure. The 15, 25 and 35 kg backpacks caused a 3, 5 and 8% ( P  < 0.05) reduction in forced vital capacity compared with the NP condition, respectively. For the same exercise stage, the power of breathing (POB) requirement was higher in the 35 kg backpack compared to NP (32 ± 4.3 vs. 88 ± 9.0 J min −1 , P  < 0.05; respectively). Independent of changes in minute ventilation, end-expiratory lung volume decreased as backpack weight increased. As backpack weight increased, there was a concomitant decline in calculated maximal ventilation, a rise in minute ventilation, and a resultant greater utilization of maximal available ventilation. In conclusion, wearing a weighted backpack during an acute bout of exercise altered operational lung volumes; however, adaptive changes in breathing mechanics may have minimized changes in the required POB such that at an iso-ventilation, wearing a backpack weighing up to 35 kg does not increase the POB requirement.