A blood lactate-based graded exercise test protocol for evaluating physiological response to wearable robots.

Area of Science:

• Biomechanics
• Human Physiology
• Robotics

Background:

• Assessing the physiological burden of wearable robots (WRs) is crucial for daily use.
• Standardized parameters are needed to reliably evaluate the impact of WRs on wearers.

Purpose of the Study:

• To introduce and validate a Graded Exercise Test (GXT) protocol using blood lactate concentration (BLC) as the primary metric for evaluating WR physiological burden.
• To compare the sensitivity of BLC-based assessment against conventional measures like heart rate (HR) and oxygen uptake (VO2).

Main Methods:

• Seventeen participants underwent a treadmill-based GXT twice: once without load and once with a simulated 10% body-weight load.
• Continuous monitoring of HR and VO2, with BLC measured every two minutes throughout the GXT.
• Analysis of BLC dynamics to identify lactate thresholds and exercise intensity transitions.

Main Results:

• BLC exhibited nonlinear dynamics, indicating transitions through lactate thresholds.
• Under loading conditions, BLC increased earlier compared to the unloaded condition, suggesting earlier anaerobic activation.
• VO2 increased proportionally with workload, but BLC provided a more sensitive indicator of metabolic perturbations.

Conclusions:

• The proposed BLC-based GXT protocol is a more sensitive method for assessing fatigue and metabolic strain imposed by WRs.
• BLC dynamics reveal exercise intensity transitions and metabolic perturbations more effectively than HR and VO2 alone.
• This protocol aids in designing wearable robots with reduced physiological burden for daily applications.