Date of this Version
Published in Transactions of the Nebraska Academy of Sciences, Volume 1 (1972).
A study was conducted to investigate the effect of various mechanical work loads on ventilation rate and heart rate, under duplicate work conditions. The task was to crank a six inch radius crank at 60 RPM against torques of O, 16, 32.1, 48 and 64.2 inch pounds equivalent to work loads of 0, 500, 1000, 1500 and 2000 ft. lb/min, respectively.
During the past few years more research efforts have been expanded in an attempt to measure the amount of energy consumed (physiological cost) by an individual performing physical work. The energy that a person consumes can be divided into two categories. The "basal metabolic rate" is that caloric expenditure required to maintain the body in a resting state. That caloric expenditure beyond the basal metabolism is the "physiological cost" of additional work.
Measurement of energy expended can be performed by purely physical methods: (1) measure the caloric value of all food, "fuel for the combustion process," or (2) measure the work and heat produced by the combustion process. Total caloric expenditure multiplied by an efficiency factor would yield the physiological cost for a given amount of work. However, it is very complicated and difficult to evaluate the human body's combustion process and to determine the efficiency of the machinery which varies from individual to individual.
A more indirect but convenient approach is to attempt to correlate the rates of body processes that are affected by muscular activity to given work rates of activities. Heart rate, blood pressure, chemical changes, ventilation rate, body temperature, and perspiration rate are all affected by muscular activity. If a correlation between one of these processes and work rate can be determined and if an efficiency factor can be developed to account for individual discrepancies in muscle condition and size, then this body process could be monitored to determine the physiological cost of muscular activity that produces a given amount of work.