# Responses and reliability of candidate intensity measures to different mental and motor load levels of an upper limb exergame in children and adolescents with neurological diagnoses

## TL;DR

This study evaluates how well different measures track physical and mental effort in children and teens with neurological conditions during exergames.

## Contribution

The paper introduces a multidimensional approach combining HRV, %ACmax, and NASA-TLX to quantify therapy intensity in neurorehabilitation.

## Key findings

- %MOVmax and NASA-TLX responded to both mental and motor intensity increases.
- HRV and %ACmax showed the highest reliability for motor load.
- NASA-TLX effort could serve as a simplified measure with variable reliability.

## Abstract

High-intensity therapy improves outcomes in (pediatric) neurorehabilitation, yet standardized intensity measures accounting for motor and/or mental demands remain scarce.

To evaluate the responses and test-retest reliability of heart rate variability (HRV), skin conductance (SC), activity counts and movement repetitions normalized for the maximal capacity (%ACmax and %MOVmax, respectively), and the NASA-TLX across personalized motor and mental load levels in children and adolescents with neurological diagnoses using upper limb exergames.

In a cross-sectional study, participants engaged in two custom exergames at three intensity levels (“very easy,” “challenging,” “very difficult”), each lasting 3 min. Responses of the candidate intensity measures were analyzed across conditions, and intraclass correlation coefficients (ICC) assessed reliability across two consecutive sessions.

30 children and adolescents with neurological diagnoses aged 9–19 years participated in the study. %MOVmax and NASA-TLX (overall, effort, mental) responded to both mental and motor intensity increases. HRV, %ACmax, and NASA-TLX physical subscale responded to motor load only. SC showed no consistent response. HRV and %ACmax demonstrated the highest reliability (ICC > 0.75), especially under motor conditions. NASA-TLX effort showed potential as a simplified surrogate for the full scale, though with variable reliability.

Changes in motor intensity were better captured than changes in mental intensity. Combining HRV, %ACmax, and NASA-TLX effort could offer a multidimensional approach to quantify therapy intensity. However, many measures lacked sufficient reliability or feasibility for clinical implementation. Further research is needed to validate these measures in real-world therapeutic settings and clarify their relationship to individual capacity.