Validation of the modified FixMáx© questionnaire

Physical fitness is an important factor for health and quality of life. For patients, physical fitness can partially determine the risk of complications from surgeries or other intensive treatments. To estimate physical fitness—expressed as maximal oxygen uptake (VO2max)—in a simple and cost-effective way, the Sports Medicine Department at Máxima MC developed the FitMáx©. The FitMáx© is a questionnaire consisting of three questions about patients’ maximum walking, cycling, and stair-climbing capacity. The questionnaire has been validated against the gold standard (an exertion test with breath gas analysis). The calculated FitMáx© score correlates at r=0.95 (0.93-0.96) with measured VO2max during an exertion test in both patients and healthy individuals.

One component of the FitMáx© for making an adequate estimation is the question about maximum cycling capacity. Internationally, this may be a weak point in the questionnaire, as cycling is not as common in every country as it is in the Netherlands. Even though the FitMáx©, without the maximum cycling capacity question, still reaches a correlation of r=0.92 (0.90-0.94) with measured VO2max during an exertion test, we aim to develop and validate a new question as part of the FitMáx© to enhance its international applicability. To achieve this, we plan to add a question about daily functioning. This question could be used as a supplement to the FitMáx© questionnaire or as a replacement for the cycling capacity question.

In the original validation study of the FitMáx©, we also administered the Duke Activity Status Index (DASI) and the Veterans Specific Activity Questionnaire (VSAQ) to the same patients for comparison.

In a previous study, the validity of the FitMáx© in measuring physical condition was examined in comparison to the gold standard—an exertion test with breath gas analysis. The aim of the current follow-up study is to improve the international applicability of the FitMáx© by validating a modified version of the FitMáx© against the gold standard.

Additionally, we want to compare the FitMáx© results with questionnaires from the literature to investigate whether the FitMáx© can provide a better estimate of the VO2max in patients and healthy individuals. For comparison, VSAQ and DASI will also be administered and included in the analyses.

Study participants will be recruited at Máxima MC in the Cardio-Pulmonary-Sports department. Individuals scheduled for an exertion test with breath gas analysis will be approached to participate in the study and complete the questionnaires. Additionally, consent will be requested to access the results of the exertion test to allow for comparison.

Participants from the validation study primarily came from the following specialties:

• Sports Medicine (mainly involving fitness assessments, meaning they were healthy)
• Cardiology
• Pulmonology
• Oncology (patients who visited the sports physician and underwent a CPET)

• Modified FitMáx©
• VSAQ
• DASI

Neglectible