Author(s): POMMERELL, F., AMCHGHAL, Y., BOYAS, S., RIVIÈRE, J.R., CADERBY, T., PEYROT, N., Institution: LE MANS UNIVERSITÉ, Country: FRANCE, Abstract-ID: 2132

INTRODUCTION:
Walking speed declines with age and is a key indicator of functional capacity, mobility, and health status in older adults. Clinical assessments such as the 10m walk, Timed Up and Go test, and the six-minute walk test (6MWT) are commonly used to characterize locomotor function and predict health outcomes. The 6MWT is widespread in clinical practice due to its simplicity, reproducibility, and strong prognostic value as an indicator of functional walking capacity in older populations [1]. The usual outcomes of the 6MWT are overall measures (total distance, mean walking speed). However, as participants are instructed to walk as fast as possible, it could inform about walking endurance, especially on the speed threshold separating physiologically sustainable and non-sustainable intensity domains.
The concept of critical speed (Vc) has been widely investigated in running. Below Vc, exercise can be sustained in a physiologically stable state, whereas above Vc, exercise induces rapid fatigability [2]. During walking, this parameter may therefore provide a clinically meaningful marker of daily-life endurance in older adults. So, this study aimed to compare, first in young adults, Vc estimated from a 6MWT to Vc derived from the time-trial (TT) reference protocol.
METHODS:
Six adults (23.6±2.6 yr) completed six walking TTs over 20, 100, 200, 400, 1200, and 2000m and a 6MWT. Participants were instructed to cover each TT distance as quickly as possible and to maximize distance during the 6MWT. Mean walking velocity for each TT was computed from completion time. Vc was estimated as the asymptotic value of a velocity-time fatiguability model fitted to TT data [3]. For the 6MWT, Vc was estimated from the instantaneous velocity (GPS) averaged over the final 30, 60, 90, and 120s of the test.
A repeated-measures ANOVA was used to compare Vc derived from the TT protocol with Vc estimated over the final 30 to 120s of the 6MWT. The agreement between the different Vc was assessed using ICC and Bland-Altman analyses.
RESULTS:
There was no difference between TT-derived Vc and Vc estimated from the 6MWT across all time windows (p=0.44). Bland-Altman analyses showed minimal systematic bias (-0.01 to -0.03 m·s⁻¹) with narrow limits of agreement (±0.18-0.20 m·s⁻¹). High ICC (0.80-0.88) supported agreement. The smallest MAEs were observed for the final 60s and 30s windows (MAE≈0.055-0.056 m·s⁻¹; RMSE≈0.08 m·s⁻¹), indicating excellent precision.
CONCLUSION:
These findings suggest that critical walking speed can be accurately estimated from mean velocity obtained from the final 30 or 60s of a 6MWT. This provides a simple and ecologically valid alternative to traditional time-trial assessments. Future studies should validate this method in older adults, and examine its potential to predict functional outcomes and daily-life performance.

REFERENCES:
[1] Otadi & Malmir, 2025, Arch Gerontol Geriatr
[2] Burnley et al., 2012, Eur J Appl Physiol
[3] Bowen et al., 2024, J Theor Biol