Physical performance tests These tests were done according to the manual of the Longitudinal Aging Study Amsterdam (LASA), and the scores relate to falls and fractures . Handgrip strength was used as an indicator of muscle strength (kg) and was assessed using a hand grip strength dynamometer (Takei TKK 5001, Takei see more Scientific Instruments, Tokyo, Japan). Subjects stood with arms and wrists stretched out at the sides of the body. They were asked to perform two maximum
force trials with each hand. For the final scores, the maximum value, whether left or right hand, was used. The inter-observer coefficient of variation was 5%. Secondly, chair stands test was used as an indicator of proximal muscle strength. To test the ability to rise from a chair, persons were asked to fold their arms across their chest and to stand up and sit down five times from a standard kitchen chair. Time taken to perform the task was measured (seconds). Functional limitations Functional limitations were assessed with a questionnaire concerning the degree of selleck chemicals difficulty of the following three activities of daily living: getting up from a chair, climbing the stairs,
and walking several hundred meters. selleck compound In these daily activities, the muscles of the upper legs are addressed in particular. The scores per activity ranged from 0 (without difficulty) to 4 (help is needed). Both summed scores (0−12) and dichotomized scores (0 = without difficulty or little difficulty, 1 = great difficulty or help needed) were analyzed. These questions were adapted from the Longitudinal Aging Study Amsterdam  and were used in a prior survey in the Netherlands among non-western immigrants . Pain Six questions were asked to assess pain. To assess proximal muscle pain, the following two questions were asked: “Do you have muscle pain in your upper legs, while walking a small distance?” Evodiamine and “Do you have muscle pain in your upper legs, while sitting on a chair?” Scores were dichotomized into 0 “no pain”
and 1 “yes” (sometimes or always). Participants were asked if they had shoulder pain during the last 2 weeks and how often they experienced shoulder pain per month. Participants were also asked if they experienced headaches during the last 2 weeks and the average number of headache episodes a year. Potential confounders The potential confounders, gender, age (at baseline), body mass index (BMI), and time of sunshine exposure (self-reported minutes per week) were included into the statistical analyses. Age was measured at baseline. BMI was calculated as weight (kg)/height (m2). Body weight was measured without heavy clothes (e.g., jacket, coat) and shoes, using a calibrated balance beam scale. Body height was measured with a stadiometer, without shoes.