# Correlation Between Instrumented Timed Up and Go Test Performance and Muscle Strength in Knee and Hip Osteoarthritis: An Exploratory, Cross-Sectional Study

## TL;DR

The study explores how the instrumented Timed Up and Go test relates to muscle strength in people with knee or hip osteoarthritis, finding stronger correlations in hip osteoarthritis.

## Contribution

The study introduces the potential of the iTUG test as an accessible alternative to isokinetic testing for estimating muscle strength in hip osteoarthritis.

## Key findings

- iTUG parameters showed moderate-to-strong correlations with muscle strength in hip osteoarthritis.
- Vertical push-off power and walk duration were most strongly associated with muscle strength in hip osteoarthritis.
- The classic stopwatch-based TUG may provide similar insights to iTUG metrics in clinical settings.

## Abstract

What are the main findings?
iTUG parameters demonstrated weak-to-moderate correlations with quadriceps and hamstring strength in knee osteoarthritis, and moderate-to-strong correlations in hip osteoarthritis.Vertical push-off power, walk duration, and total iTUG duration showed the strongest associations in hip osteoarthritis population.

iTUG parameters demonstrated weak-to-moderate correlations with quadriceps and hamstring strength in knee osteoarthritis, and moderate-to-strong correlations in hip osteoarthritis.

Vertical push-off power, walk duration, and total iTUG duration showed the strongest associations in hip osteoarthritis population.

What are the implications of the main findings?
The iTUG test could provide a simple and accessible estimation of lower-limb muscle strength when isokinetic evaluation is not available.The classic stopwatch-based TUG may offer comparable clinical insights to iTUG-derived metrics, supporting its use in daily rehabilitation settings.

The iTUG test could provide a simple and accessible estimation of lower-limb muscle strength when isokinetic evaluation is not available.

The classic stopwatch-based TUG may offer comparable clinical insights to iTUG-derived metrics, supporting its use in daily rehabilitation settings.

Muscle weakness is a key contributor to functional limitation in individuals with hip (HOA) or knee osteoarthritis (KOA). Identifying accessible and objective tools to estimate muscle strength could improve clinical assessment and rehabilitation monitoring. This exploratory cross-sectional study investigated the relationship between parameters derived from the instrumented Timed Up and Go test (iTUG), and isokinetic quadriceps and hamstring strength in individuals with KOA or HOA. Thirty-six participants with KOA and 21 with HOA were assessed. Quadriceps and hamstring peak torques were measured at 60°/s using an isokinetic dynamometer. The iTUG was performed with a sacrum-mounted inertial measurement unit. Correlations between iTUG parameters and lower-limb muscle strength were weak-to-moderate in KOA (r = −0.398 to −0.516, p < 0.05) and moderate-to-strong in HOA (r= −0.537 to −0.843, p < 0.05). Total iTUG duration strongly correlated with the traditional stopwatch TUG (r = 0.91, p < 0.01), suggesting that the classic stopwatch-based TUG may offer comparable clinical insights to certain iTUG-derived temporal metrics. The iTUG test reflects lower-limb muscle weakness, especially in HOA, with vertical push-off power and temporal metrics showing the strongest relationships. These results support the use of iTUG as an accessible tool for estimating muscle weakness when isokinetic testing is unavailable. However, these findings should be interpreted with caution given the small sample size.