Background
Some evidence suggests that alternations between physical and cognitive work tasks may be a viable option for job rotation, since production can be maintained without excessive fatigue. Effects on fatigue and pain of the temporal distribution of physical and cognitive tasks are, however, uncertain. The aim of this study was to examine development of fatigue and pain during physical and cognitive work tasks of different difficulties, alternating in different temporal patterns.
Methods
Fifteen women performed alternating bouts of a physical task (phys) and a cognitive task (CT) for a total of 100 minutes. Four experimental conditions were tested in a repeated-measures design. Conditions 1 and 2 consisted of five long-cycle sequences (phys+CT, 14+6 minutes), and in conditions 3 and 4, 10 short-cycle sequences (7+3 minutes) were performed. Each temporal pattern was completed with an easy or a difficult CT. Muscle fatigue was assessed using surface electromyography (EMG) from the right trapezius, and perceived fatigue and pain in the right shoulder was assessed using CR-10 ratings. Effects of time and experimental condition on these outcomes were tested using ANOVA.
Results
Perceived fatigue and pain in right shoulder after pipetting work bouts increased in all four conditions (long-cycle, fatigue F=5.68, p<0.001, pain F=4.12, p=0.01; short-cycle, fatigue F=10.59, p<0.001, pain F=5.45, p<0.001). Trapezius EMG did not change significantly across work bouts (long-cycle, F=2.14, p=0.09; short-cycle, F=1.03, p=0.42). Irrespective of the temporal alternation pattern, neither EMG nor fatigue and pain were influenced by CT difficulty (CT main effect and CT×time interaction: EMG, all F≤2.5, p≥0.1; fatigue and pain, all F≤2.0, p≥0.7).
Conclusions
The temporal pattern of alternations between a repetitive physical task and a CT did not influence fatigue development, and the difficulty level of the CT did not significantly influence fatigue and pain, irrespective of the temporal alternation pattern.
2019.
10th International Scientific Conference on the Prevention of Work-related Musculoskeletal Disorders, 2-5 September 2019, Bologna, Italy