Validity of a test means that the test measures what it is supposed to measure and not something else. The Polar Fitness Test was originally developed on 305 healthy Finnish men and women in a study, where VO2max prediction was developed using artificial neural network analysis. The correlation coefficient between the laboratory measured VO2max and the neural network prediction value was 0.97 and the mean error in the VO2max prediction was 6.5 % which is good compared to any other predictive tests of VO2max.
In further development of the test, 119 fitness measurements of healthy American men and women were included in the final development of the neural network, making a total of 424 subjects. Based on these results the artificial neural network was modified into Polar Fitness Test. The test was validated in a study on 52 healthy men, who didn't belong to the group on whom the test was developed. The mean deviation in the Polar Fitness Test prediction was less than 12 %. The validity of the Polar Fitness Test is considered to be good.
The reliability of a test is a measure of how consistent and reproducible the test results are on consecutive trials. The reliability of the Polar Fitness Test is good. When 11 subjects repeated the test in the morning, in the middle of the day and in the evening during eight days, in both sitting and laying positions, the average individual standard deviation of consecutive test results was less than 8 % from the individual mean value. The standard deviations calculated separately for each time of the day were all smaller than the standard deviation of all results. This indicates that the test can be conducted at any time of the day but it should always be repeated at about the same time.