Referring to the working person, several dimensions of human work capacity can be distinguished theoretically, even if it is difﬁcult to account for the differentiation in dimensions in a metrological way concerning the concrete application. These dimensions are called, on the one hand, ability and, on the other hand, willingness to perform. In regards to ability the characteristics, which cause the achievement structure of a working person are considered physiologically as achievement capacity of the organs and/or organ systems and psychologically as achievement potential of psychological functions and/or appropriate components.
Willingness to performis determined physiologically by the excitation level of organs and/or organ systems in the psychological sense by achievement attitudes and motives such as needs, interests, intentions, or convictions. Components of the willingness to performare, thus, a necessary condition, in order to utilize the existing potential of abilities. This means that only people who are physiologically above a certain excitation level (e.g., muscle tonus) and those who are additionally motivated (psychological dimension) can achieve the performance level, which they are enabled to achieve due to their physiological and psychological
The characteristics of a person who has the ability to perform is inﬂuenced by four categories. These are the constitution-, disposition-, qualiﬁcation-, and adaptation characteristics . Constitution characteristics are unchangeable ratios in the life cycle of humans. Among these characteristics are gender, somatotype, and ethnical origin. Disposition characteristics are variable, however, the working person has no direct inﬂuence on this. Disposition characteristics cover the age, body weight, the state of health, and the intelligence of a working person. Beyond that, the biorhythm belongs to the disposition characteristics. This means that the human efﬁciency in the course of a day is subject to ﬂuctuations. The entirety of all knowledge, skills, and experiences of a working person are understood as qualiﬁcation characteristics, which a working person must have for carrying out activities at the workplace.
Characteristics, which affect the human ability and are changeable at short notice are called adaptation characteristics. Adaptation characteristics refer to the fatigue and recovery, as well as the strain of a working person. With the beginning of an activity numerous physical and psychological conversion procedures start, whereby humans adapt increasingly to the workload caused by the activity. Manual labor, for example, leads to a rise of the heart rate and the muscle blood circulation, in order to be able to meet the demanded achievement. The realization became generally accepted that an optimal achievement of working humans is only ensured in the long term, if the fatigue caused by the work stays within limits.
Most of the determinants mentioned for the ability are mutually dependent on each other, for example, somatotype and body weight, age and experience, skills and strain. Differences between people or changes within a person, however, do not have to lead inevitably to differences in the achievement. Measurable effects on the achievement cannot be determined due to the existence of mutual compensation mechanisms. Constitution characteristics are solely inﬂuenced by the selection of personnel. Disposition characteristics can also be affected by other measures. Speciﬁcations of some characteristics can be changed within a limited range also through measures of work system design.
For example, realizations of the inﬂuence of biorhythm on the human ability effect the shift work models. Qualiﬁcation characteristics can be determined by both, a purposeful selection of personnel and by measures of the work system design and personnel development. For example, the introduction of a continuous improvement process (CIP) can lead to the fact that employees exchange knowledge and experiences during operational problem solving, causing the qualiﬁcation level within the CIP-team to increase. Adaptation characteristics are not or only
indirectly affected in their developments by a selection of personnel. Measures of the work system design can exert inﬂuence on variables at short notice such as strain and fatigue. For example, organizational rules of recovery periods can help to avoid an excessive demand and a possible harm to working persons.
The willingness to perform, the work motivation of a person, results from the reciprocal effects
between personal motives of the working person and the motivation potential of the work. Neither the motives nor the motivation potential of the work alone are sufﬁcient, in order to explain the development of work motivation. The motivation potential of work results from the expectations of employees to be able to achieve their motives. For example, motivation potentials regarding achievement, power, and integration can be differentiated from each other, since motivation potential always refers to speciﬁc motives. A work situation with a high achievement-related motivation potential is, for example, characterized by establishing a range of decision and activity for employees in which a complete and in their view important task with adequate difﬁculty can be worked on. Motivation potential regarding power always contains work activities, whenever the work activity is implemented by several employees simultaneously and the task makes it necessary that a person (e.g., guidance person) affects other people in the sense of achieving a certain goal.
High motivation potential regarding integration exhibit work activities, which give many opportunities to the working person to achieve social contacts and maintain them. If motivation potentials are highly developed, these do not lead inevitably to a high motivation. Motivation potentials are regarded, therefore, as a condition of work motivation. For example, if a work system is spatially arranged in such a way that it permits interactions between working persons, this leads to a high motivation for the employees with a strong integration motive. For people with low integration motive, however, the possibility of exchanging itself with colleagues does not lead to increased motivation.