# Evolution of Rate of Force Development (RFD) in the Isometric Deadlift Exercise Among Primary and Secondary Education Students

## TL;DR

The study measured how quickly children and adolescents can develop force during a deadlift exercise, finding that strength improves with age, especially in boys.

## Contribution

The study introduces the isometric deadlift as a practical and low-pain method for assessing strength development in schoolchildren.

## Key findings

- Rate of force development (RFD) increased significantly in secondary school boys.
- Pain during the exercise was rare and not linked to RFD or maximal force.
- The deadlift is a feasible and safe method for strength assessment in educational settings.

## Abstract

Strength is a central axis of physical activity and sets the right evolutionary direction for children and adolescents, creating adaptations that determine functional health in adulthood. Therefore, its development and supervision are essential in the future. This study aimed to measure the rate of force development (RFD) in a sample of primary and secondary school children using the deadlift exercise. In a mixed sample of 227 students aged 9–16 years, two attempts of the isometric deadlift exercise were performed using a hand-held dynamometer. Pain perception was recorded after each attempt was made. RFD evolved in both stages, with a greater difference in boys in Secondary School (p = 0.0017), and no additional differences in the rest of the variables between sexes and stages. Pain during execution was infrequent in this sample and showed no consistent association with RFD or maximal force in adjusted exploratory models. Key outcomes (maximal force and RFD_{0–200}) were summarized by sex and educational stage; RFD was computed as ΔF/Δt over 0–200 ms from contraction onset. The main findings highlight the expected progression of strength, especially in boys, and support the deadlift as an accessible alternative for strength assessment in educational settings and health-oriented recreational activities, given its low incidence of pain during execution in this population.