Title: fit2dive - A field test for assessing the specific capability of underwater fin swimming with SCUBA

Exercise modalities such as cycle ergometry do not mimic the specific movements of fin swimming underwater. Therefore, there is a need to develop a specific diving capability assessment procedure. The purpose of the study was the application of a standardized field test to assess and rate underwater swimming performance. The fit2dive-test consists of an incremental protocol that is performed in a pool (<5 m depth). The underwater swimming speed is increased stepwise by 0.2 m·s-1, starting with 0.4 m·s-1 until the subject’s subjective exhaustion is attained. Time of break-off (fit2dive-time), swimming technique (e.g. range of motion (ROM) of hip and knee joints) and equipment configuration was recorded via a standardized checklist. Subjects with the highest hip and knee flexion had lower fit2dive-times (373 ± 119 s; p<0.01) than those in the normal hip and knee flexion ROM category (448 ± 104 s). Further, divers using full foot fins had significantly higher (p<0.001) fit2dive-times (474 ± 97 s) than divers with adjustable strap fins (375 ± 104 s). The fit2dive test indicates the specific capability of underwater fin swimming. The results allow identifying weak factors such as underwater swimming technique or equipment configuration.