[Deficiencies and resources of working population in relation to age: a multidisciplinary approach]

The aging of the population as a whole and the later age at which young people start work are increasing the percentage of older employees. In situations where the working conditions are highly demanding, as in shiftwork, time-pressure jobs, and adaptation to modern technology or skill diversification, this demographic trend may cause serious problems. The way in which job constraints and demands are withstood at various ages should be considered in relation to health, which is often, whether implicitly or explicitly, a selection criterion in the work place. The connection between work and health can rarely be described by a single causal relationship and requires specific epidemiological methods. Moreover, a health problem linked to age can have a feedback effect on the manner in which a job is performed. While these problems do indeed arise in the areas of work and health, they are nonetheless usually symptoms of modifications that have taken place in the work activity itself. The ergonomic approach nevertheless allows us to improve our understanding of changes in work behavior as age increases, as experience is gained, and as skills are acquired. Men and women on the job are not passive spectators of the good or poor fit between the characteristics of their jobs and their own functional state. Consciously or unconsciously, they modify their operating modes (movements, work pace, posture, etc.), reduce their effort level in some subtasks, make more plans to avoid emergency situations, check the outcome of their actions so as to reduce errors that would be costly to correct, and adjust the distribution of tasks in cooperative and collective work situations. But these strategies can only be implemented if the work conditions and organization foster and promote them.