# Neuromotor functions across the lifespan: percentiles from 6 to 80 years

## TL;DR

This study tracks how neuromotor abilities change from age 6 to 80, showing how performance peaks and declines over time, and how factors like sex and BMI influence these changes.

## Contribution

The study provides detailed reference curves for neuromotor functions across a wide age range and identifies sex- and task-specific patterns of performance.

## Key findings

- Motor functions rapidly increase before age 10, peak between 20 and 40, and decline afterward.
- Tasks requiring muscle force decline faster than those involving isolated movements.
- High BMI is linked to worse balance and gross motor performance but not other motor domains.

## Abstract

To investigate the dynamics of neuromotor functions from 6 to 80 years with the Zurich Neuromotor Assessment (ZNA) and to provide reference curves for clinical and research use.

Neuromotor data on 1620 individuals (828 females) measured with the ZNA and ZNA-2 between 1983 and 2023 were extracted from 11 studies, all performed at the same center in the region of Zurich, Switzerland. Performance on 14 motor tasks was modeled as a function of age and sex while controlling for differences in testing procedures that occurred over the period spanned by the studies. The age of peak performance was identified for each task. Motor performance was converted into standard deviation scores (SDSs) at the task level and combined into the five motor components of the ZNA-2: fine motor, pure motor, balance, gross motor, and contralateral associated movements. The effect of body mass index (BMI) on motor component SDSs was also investigated.

The data showed a rapid increase in motor functions during the first years, particularly before age 10 years, followed by a leveling in performance between the ages of 20 and 40 years. Afterward, a decrease in motor functions was observed in most tasks. However, the age of peak performance and the rate of decline varied greatly between the tasks: motor functions in tasks requiring muscle force deteriorated faster than those involving isolated movements, which showed only mild declines at older ages. Males reached peak performance on average 1 year later than females. High BMI (SDS > 1) was associated with lower balance and poorer gross motor functions.

Neuromotor functions undergo dynamic changes throughout the lifespan from early childhood to older adulthood, with peak performances and declines depending on type of motor task and sex. High BMI negatively impacts balance and gross motor functions but not other neuromotor domains. Our findings may inform clinical practice and interventions aimed at optimizing motor functions across the lifespan.