the metabolic cost of backpack and shoulder load carriage

Metabolic costs of load carriage with different container sizes S. J. MORRISSEY & Y. H. LIOU Six well-trained male subjects carried boxes of varying box width and weight at varying speeds on a level treadmill until steady-state heart rates were obtained. Analysis of the steady-state data for heart rate and metabolic cost led to development of highly accurate predictor models for both factors. The metabolic-cost model accounted for over 94% of the variance (R2>0·94), and the heart-rate model accounted for over 81% of the variance present (R2>0·81). Evaluation of other models for predicting physiological response to carrying loads found their predictions to differ significantly from the data of the present study. Key words: WorkLoad carriageMetabolic costModellingComparison of Selected Perceptual Variables for Backpacks with Internal and External Frames AbstractDifferences in perceptions of comfort, exertion, balance, and heart rate were investigated with two types of backpack.
Subjects were 20 male volunteers (M age = 24.3 yr., SD: 3.6, M height= 180.02 cm, SD: 8.0, and M weight = 86.46 kg, SD: 14.84). Following oral briefing and practice trials, each subject was fitted at random with either an internal- or external-frame backpack containing 18.2 kg. By random, cross-over design, subjects completed a 30-m simulated hiking trail consisting of 16 separate obstacles designed to resemble actual off-trail hiking. borderlands tps backpackTrials were conducted in a controlled environment with the walking intensity regulated by a metronome. hp backpack para laptop de poliester basica hp 16Upon completion of each trial, the subjects rated the experience on perceived comfort, balance and stability, and rating of perceived exertion. eberlestock lodrag backpack
Heart rate was recorded immediately prior to and following each trial. Analysis yielded a significant difference only on rating of perceived exertion in favor of the internal-frame backpack. Under limited circumstances, these data suggest that both types of backpacks provide similar comfort and balance and stability; however, internal frames in backpacks may reduce perceived exertion during short, demanding hikes.ReferencesChooseTop of pageAbstractReferences <
For more information or tips please see 'Downloading to a citation manager' in the Help menu. RIS (ProCite, Reference Manager)EndNoteBibTexMedlarsRefWorks Comparison of Selected Perceptual Variables for Backpacks with Internal and External Frames View permissions information for this article Send me a copy Energy Expenditure of Heavy Load Carriage ROGER G. SOULE , KENT B. PANDOLF & RALPH F. GOLDMAN Fourteen subjects (22 yr, 175 cm, 72 kg) walked for 20 min on a treadmill at 3-2, 4-8, or 64 km h-1 carrying 35, 40, 45, or 50 kg; during a second phase, ten additional subjects (22 yr, 178 cm, 75 kg) attempted to walk for 45 min at the same speeds carrying 60, 65. or 70 kg Energy expenditure when expressed as cm3 oxygen per minute per kilogramme of total weight (man + clothing + load) agreed, for the no load condition, with literature values. After deducting the individual's no load cost, the resulting net energy expenditure for carrying the loads, when expressed as cm3 kg-1 min-1 was generally constant at each speed;
i.e. loads from 35 to 70 kg showed no statistical differences in energy expenditure per kilogramme at 3 2 and 4 8 km h-1. At 6-4 km h-1 carrying 70 kg, the average measured cost per kg was statistically different (p < 005) than carrying 35 kg at this speed; subjects were working at greater than 90% of their maximal [Vdot]02 levels carrying 70 kg. similar comparison of the measured cost per kg between loads of 40 and 65 kg was statistically the same at 6 4 km h-1. The general constancy of measured energy expenditure per kg for loads even up to 70 kg, probably depends on the condition that the load is well balanced and close to the centre of the body. As reported earlier, higher costs are associated with loads in unbalanced positions. Thus, the limitations commonly encountered in load carrying capacity may arise from poor positioning of the load rather than from the weight of the load per LOAD CARRIAGE AND ITS PHYSIOLOGICAL IMPACT LOAD CARRIAGE AND ITS BIOMECHANICAL IMPACT
LOAD CARRIAGE AND ITS HEALTH IMPACT The female athlete triad Urinary Incontinence and Pelvic Floor Muscle Function STRATEGIES TO IMPROVE FEMALE LOAD CARRIAGE PERFORMANCE AND MINIMISE INJURIES Modification of Load Carriage Equipment to meet Female Soldier Requirements Limitations of this paper and recommendations for future work Download a PDF of this articleCharacterization of Pulling Forces Exerted by Primary School Children While Carrying Trolley Bags Article first published online:Issue published: AbstractCarriage of school items by children remains an issue of concern, mainly due to the large loads they have to bear, starting from early age when the musculoskeletal structure is still under development. As such, children are potentially exposed to important risks of acute or chronic injuries due to such carriage. While backpack remains the most common modality, in recent years trolley bags are increasingly considered and used. Trolleys may be of benefit, as much of the load can supported by the ground, and the muscular effort is limited to a pulling force.
Nevertheless, there are situations (like stair ascent and descent, steps, and ramps) where the pulling force increases or, in some cases, has to be fully supported by a single arm. Under such conditions, the use of trolley bag might be disadvantageous versus a backpack, in that the latter allows a symmetrical distribution of the load on the body in a range of conditions. To provide more empirical evidence, which at present is very limited, this study aimed to characterize the pulling forces needed when using a school trolley bag, on a route that includes level and inclined ground surface, steps, and stairs. A sample of 195 students of primary school (age 8-11) participated, and they were asked to pull an instrumented trolley loaded with school items (total load = 62 N) from the school entrance to a classroom located one floor up in the school building. The results, expressed in terms of “pulling force vs. time” curves, show that particularly during stairs ascent and descent, one arm may exert quite large dynamic forces, and that these forces can be up to twice the mass of the carried load.