Differences in upper limb load between sitting and standing postures: A systematic review and meta-analysis

The aim of the study was to quantify the differences in upper limb loads between standing and sitting postures. Workstations that secure alterations between sitting and standing are a novel occupational intervention. Knowing the differences in upper limb musculoskeletal load between sitting and standing would allow for a more complex assessment of work-related exposure and establishing the optimal timing of transitions between sitting and standing. The data from the literature search (upper limb muscles strength and activity recorded while sitting and standing) were analyzed using a continuous random effects model. Pooling was conducted using the Ratio of Means with inverse variance weighting. Egger's regression test, along with Duval and Tweedie's trim and fill approach assessed and corrected publication bias. The Cochran's Q, Tau 2 , and I 2 evaluated heterogeneity. The results revealed increased muscular activity while sitting. The deltoid muscle had the largest effect size, the trapezius a somewhat smaller. The biceps and triceps muscles produced a low effect size. Wrist extensor exhibited the opposite tendency. In the case of forces (handgrip and pulling), a small effect size indicates more force capabilities in standing. Concluding - in a standing posture the contraction of the upper limb muscles is lower than when performing the same tasks during sitting. Impact of posture on upper limb maximum strength capabilities is inconclusive. The results can give input to establishing optimal time of alterations between sitting and standing and to development of methods that serve to assessment of work-related upper limbs exposure.