Introduction Japan faces a serious national issue of declining worker numbers due to low birth-rate and longevity. There is an increased need to maintain workers’ health and extend the working years prior to workforce retirement. Hence, research in workers’ physical fitness will play a significant role in occupational health issues. Cardiorespiratory fitness (CRF) assessed by maximal oxygen consumption (VO_2max) plays an important role in workers’ health. However, measuring VO_2max can be burdensome for subjects and requires skilled examiners. This is a practical disadvantage for including VO_2max in workplace health check-ups. In this study, we developed a new CRF measurement procedure in lieu of measuring VO_2max.

Methods Our study participants included 101 Japanese workers (55 men and 46 women, aged 30 to 59 years). We measured subjects’ VO_2max by the Bruce protocol using treadmill exercise and an indirect calorimeter. Subjects also completed two newly devised assessments: (1) a step-test consisting of a 3 min stepping exercise followed by a 2 min rest and (2) a questionnaire measuring workers’ physical activity level during working time and during non-working time on workdays and non-workdays. We conducted multiple regression analyses with VO_2max as a dependent variable and parameters obtained from the procedure as independent variables.

Results We chose the combined heart rates during the step-test’s exercise and recovery periods and the questionnaire’s total score as significant (p<0.05) independent variables. In a multiple regression model, age (years), sex (1, 0), heart rates during the step-test (beats) and total score on the questionnaire (points) accounted for 58.6% of the VO_2max variance.

Conclusion The procedure we developed can be performed without a heavy exercise burden on the subject or special skills of the examiner. This study suggests that the procedure can potentially be used to assess CRF in the worker’s health check-ups where VO_2max measurements are not available.