Figure 1

Order and time schedule for the data collection. Recording equipment was mounted immediately after arrival at the laboratory (~4:45 pm, range 4:30–5:00 pm) followed by an experimental session with laboratory recordings. After an evening meal at ~8:30 pm the subjects were free to choose activity until bedtime. sEMG activity (trapezius, deltoideus, and biceps) and heart rate were recorded continuously from start of the experimental session until bedtime. Pain (shoulder/neck, low back), general tension, and perceived stress were scored on Visual Analogue Scale (VAS) at four occasions.