Age-related changes in upper body adaptation to walking speed in human locomotion

Assessments of changes in gait stability due to aging and disease are predominantly based on lower extremity kinematic and kinetic data. These gait changes are also often based on comparisons at preferred speed only. The purpose of this experiment was to: (1) examine age-related changes in range of motion and coordination of segments of the upper body during locomotion; and (2) investigate the effects of a systematic walking velocity manipulation on rotational motion and coordination. Participants (n = 30) walked on a motor driven treadmill at speeds ranging from 0.2 to 1.8 m/s and were divided into three groups with mean ages of 23.3, 49.3 and 72.6 years, respectively. Seven high-speed infrared cameras were used to record three-dimensional kinematics of the pelvis, trunk and head. Dependent variables were amplitude of segmental and joint rotations, as well as relative phase to assess coordination between segments. Although no differences in stride parameters were found between the groups, age-related changes in movement amplitude in response to speed manipulations were observed for all segments and joints. Pelvic rotations in sagittal, frontal and transverse planes of motion were systematically reduced with age. Older individuals showed reduced trunk flexion-extension in the sagittal plane and increased trunk axial rotation in the transverse plane. Coordination analysis showed reduced compensatory movement between pelvis and trunk in older individuals. These findings support the importance of systematic manipulation of walking velocity and three-dimensional upper body kinematics in assessing age-related changes in locomotor stability and adaptability

Does Modern Organization and Governance Threat Solidarity?

This article focuses on solidarity behaviours of employees to team members (horizontal solidarity behaviour) and to their manager (vertical solidarity behaviour). The question is asked to what extend and how are both types of solidarity related to three aspects of modern organization and governance: dual earner families, flexible labour contracts, and formal and informal governance structures. Survey data of 17 Dutch organizations (N=1347) show in relation to dual-earner families that having children has a positive relationship with horizontal solidarity behaviour, and working overtime has a positive relationship with vertical solidarity behaviour. Related to the flexible labour contracts, no relationship was found with type of labour contract and expected years within the organization. Finally, some traits of informal and formal governance structures, namely information on rules and the presence of explicit fair play rules are fond to be positively related to solidarity. Copyright Kluwer Academic Publishers 2004employment relationships, formal and informal governance structures, solidarity behaviour,