Background: Despite extensive efforts, issues like obesity and poor physical capacity remain challenges for a healthy work life in several occupations. The Goldilocks work principle offers a new approach, encouraging design of productive work to promote physical capacity and health. This paper presents the protocol for the Goldilocks-childcare study, a randomised controlled intervention trial aiming to evaluate the effectiveness of implementing the Goldilocks work principle in childcare. The primary aim of the intervention is to increase time in moderate to vigorous physical activity (MVPA) by having the childcare workers act as active role models for children in daily playful physical activities, and thereby improve cardiorespiratory fitness and health of the workers.

Methods/ design: The study is a cluster-randomised trial with a usual-practice wait-list control group. The 10-week intervention consists of two phases. In the first, the childcare workers will participate in two participatory workshops aiming, a) to develop playful physical activities (‘Goldilocks-games’) for children in which childcare workers participate as active role models at MVPA intensity, and b) to develop action plans for implementation of the Goldilocks-games in daily work routines. In the second phase, childcare institutions will implement the Goldilocks-games. The primary outcome is working time spent in MVPA, and secondary outcomes are cardiorespiratory fitness, sleeping heart rate, perceived need for recovery, and productivity. Primary outcome and process evaluation will be based on direct measurements of physical activity and heart rate, determination of cardiorespiratory fitness, and questionnaires.

Discussion: If proven effective, the Goldilocks work principle has a large potential for promoting sustainable health and working lives of childcare workers.