Five-times sit-to-stand test: Exploring movement synergies and anthropometric influences

The five-times sit-to-stand test (5TSTS) is widely used to assess functional mobility, measuring the time required for an individual to complete five consecutive sit-to-stand movements as quickly as possible.

This study aimed to investigate movement components or synergies-termed principal movements (PMs)-underlying 5TSTS performance and to examine how anthropometric characteristics and 5TSTS completion time relate to the composition and neuromuscular control of these PMs.

Principal component analysis (PCA) was applied to three-dimensional position data from 50 young adults (median age 24 [21-26] years) performing the 5TSTS. PM composition was quantified from principal positions, while the neuromuscular control was assessed from principal accelerations.

Anthropometric characteristics significantly influenced the composition of specific PMs. Greater body weight (p = 0.005) and height (p = 0.002) were positively correlated with PM₁ (sit-to-stand transition) but negatively correlated with PM₂ (trunk extension, p = 0.006 for weight, p = 0.001 for height) and PM₄ (anterior body sliding on the chair, p = 0.024 for weight, p = 0.007 for height). Shorter 5TSTS times were associated with higher acceleration magnitudes across PM₁-PM₄ (all p < 0.001), reflecting greater neuromuscular output and more dynamic postural control.

Body size strongly shapes the composition of movement synergies during 5TSTS, underscoring the importance of anthropometric factors in functional mobility assessments. Furthermore, 5TSTS time reflects the neuromuscular control of movement synergies and may serve as a clinically meaningful indicator of neuromuscular control, dynamic stability, and functional performance.