Advances in selected areas of human work physiology

Human work physiology is a fast growing field of research which has much to offer to human biologists. The field is too broad and complex to be adequately covered in a single review. Authors have retained topics which, in their judgment, are of interests to human biologists and have been the object of much recent research. Distinctions are made between aerobic and anaerobic capacities and powers and indications given concerning their work-associated characteristics in humans. The so-called concept of anaerobic threshold is defined, and recent evidence pertaining to its metabolic basis and physiological description is presented. Discussions about the extent of the specificity of each measured attribute lead to the conclusion that care must be taken when testing only one capacity or a given power of the human machine. Material accumulated during the last decade or so concerning the human skeletal muscle structure and composition is briefly reviewed. Major findings about the human muscle energy production systems and their exercise-associated variations are described. Changes taking place in maximal aerobic power and in submaximal working capacity during growth are analyzed comparing prior consensus with more recent data. Discussion then turns to the general theme of causal sources of human variation in relevant attributes. Research dealing with the heritability of respiratory functions, heart size, muscle characteristics and aerobic capacities and powers are reviewed. Finally, the response to work and exercise training (trainability) of the maximal aerobic power is discussed with respect to the mature, the growing and the aging organism.