Summary
Limited information is available regarding the physiological responses to prolonged load carriage. This study determined the energy cost of prolonged treadmill walking (fixed distance of 12 km) at speeds of 1.10 m·s−1, 1.35 m·s−1, and 1.60 m·s−1, unloaded (clothing mass 5.2 kg) and with external loads of 31.5 and 49.4 kg. Fifteen male subjects performed nine trials in random order over a 6-week period. Oxygen uptake (VO2) was determined at the end of the first 10 min and every 20 min thereafter. A 10-min rest period was allowed following each 50 min of walking. No changes occurred in VO2 over time in the unloaded condition at any speed. The 31.5 and 49.4 kg loads, however, produced significant increases (ranging from 10 to 18%) at the two fastest and at all three speeds, respectively, even at initial exercise intensities less than 30% VO2max. In addition, the 49.4 kg load elicited a significantly higher (P<0.05) VO2 than did the 31.5 kg load at all speeds. The measured values of metabolic cost were also compared to those predicted using the formula of Pandolf et al. In trials where VO2 increased significantly over time, predicted values underestimated the actual metabolic cost during the final minute by 10–16%. It is concluded that energy cost during prolonged load carriage is not constant but increases significantly over time even at low relative exercise intensities. It is further concluded that applying the prediction model which estimates energy expenditure from short-term load carriage efforts to prolonged load carriage can result in significant underestimations of the actual energy cost.
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References
Åstrand PO (1956) Human physical fitness with special reference to sex and age. Physiol Rev 36:307–335
Åstrand I (1967) Degree of strain during building work as related to individual aerobic work capacity. Ergonomics 10:293–303
Bink B (1964) Additional studies on physical working capacity in relation to working time and age. Ergonomics 83–86. Proceedings of 2nd International Ergonomics Congress, Dortmund
Casaburi R, Storer TW, Ben-Dov I, Wasserman K (1987) Effect of endurance training on possible determinants of VO2 during heavy exercise. J Appl Physiol 62:199–207
Daniels JT (1985) A physiologist's view of running economy. Med Sci Sports Exerc 17:332–338
Epstein Y, Rosenblum J, Burstein R, Sawka MN (1988) External load can alter the energy cost of prolonged exercise. Eur J Appl Physiol 57:243–247
Fitzgerald PI, Vogel JA, Miletti J, Foster JM (1987) An improved portable hydrostatic weighing system for body composition. US Army Research Institute of Environmental Medicine. Tech Rep T4/88, Natrick, Mass.
Givoni B, Goldman RF (1971) Predicting metabolic energy cost. J Appl Physiol 30:429–433
Goldman RF, Iampietro PF (1962) Energy cost of load carriage. J Appl Physiol 17:675–676
Hagberg JM, Mullin JP, Nagle FL (1978) Oxygen consumption during constant-load exercise. J Appl Physiol 45:381–384
Haisman MF (1988) Determinants of load carriage. Appl Ergonomics 19:111–121
Hughes AL, Goldman RF (1970) Energy cost of “hard work”. J Appl Physiol 29:570–572
Kalis JK, Freund BJ, Joyner MJ, Jilka SM, Nittolo J, Wilmore JH (1988) Effect of β-blockade on the drift in O2 consumption during prolonged exercise. J Appl Physiol 64:753–758
Levine L, Evans WJ, Winsmann FR, Pandolf KB (1982) Prolonged self-paced hard physical exercise comparing trained and untrained men. Ergonomics 25:393–400
Martin PE, Nelson RC (1986) The effect of carried loads on the walking patterns of men and women. Ergonomics 29:1191–1202
McArdle WD, Katch FI, Katch VL (1985) Exercise physiology. Lea and Febiger, Philadelphia
Michael ED, Hutton KE, Horvath SM (1961) Cardiorespiratory responses during prolonged exercise. J Appl Physiol 16:997–1000
Mitchell JS, Sproule J, Chapman CB (1957) The physiological meaning of the maximal oxygen uptake test. J Clin Invest 37:538–547
Myles WS, Eclache JF, Beaury J (1979) Self-pacing during sustained, repetitive exercise. Aviat Space Environ Med 50:921–924
Pandolf KB, Givoni B, Goldman RF (1977) Predicting energy expenditure with loads while standing and walking very slowly. J Appl Physiol 43:577–581
Pimental NA, Shapiro Y, Pandolf KB (1982) Comparison of uphill and downhill walking and concentric and eccentric cycling. Ergonomics 25:373–380
Redfearn JWT (1960) Th eosinopenia of physical exercise. Ergonomics 3:17
Roberthson H (1984) Carrying a load in the military — historical and physiological perspective. FOA Rep C54059-HI. Swedish National Defense Research Institute
Saha PN, Datta SR, Banerjee PK, Narayane GG (1979) An acceptable work load for Indian workers. Ergonomics 22:1059–1071
Saltin B, Stenberg J (1964) Circulatory responses to prolonged severe exercise. J Appl Physiol 19:833–838
Sawka MN, Knowlton RG, Critz JB (1979) Thermal and circulatory responses to repeated bouts of prolonged running. Med Sci Sports 11:177–180
Soule RG, Goldman RF (1972) Terrain coefficients for energy cost prediction. J Appl Physiol 32:706–708
Soule RG, Pandolf KB, Goldman RF (1978) Energy expenditure of heavy load carriage. Ergonomics 21:373–381
Wilmore JH (1969) A simplified method for determination of residual lung volumes. J Appl Physiol 27:96–100
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Patton, J.F., Kaszuba, J., Mello, R.P. et al. Physiological responses to prolonged treadmill walking with external loads. Eur J Appl Physiol 63, 89–93 (1991). https://doi.org/10.1007/BF00235175
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DOI: https://doi.org/10.1007/BF00235175