Measuring physical fitness becomes more important. Yet most instruments depend upon the function of the lower extremities. Hence, we investigated whether an adapted submaximal arm crank test on an ergometer for the upper body is reliable to use, and if the submaximal test for the arm crank ergometer is valid compared to the test on the bicycle ergometer. Different types of reliability measures of the adapted submaximal test on an arm crank ergometer were assessed in healthy volunteers, such as test-retest, interobserver, interergometer, and between arm crank and bicycle ergometer. A crossover design was used. The measurements were proportionally distributed over 30 volunteers. Based on the intraclass correlation coefficient (ICC) and the magnitude of within-person differences, we revealed a good reliability of the submaximal test. For the test-retest reliability, the ICC was 0.76, the interobserver reliability was 0.82, and the interergometer reliability 0.63. In addition, the criterion validity was also tested by comparing the calculated VO2max during the submaximal test on the arm crank ergometer and on the bicycle ergometer. Between VO2max on the arm crank and bicycle ergometer, an ICC of 0.64 was found. The results of the submaximal test on the arm crank ergometer are reliable and valid as compared with those on the bicycle crank ergometer. We showed that the submaximal test on the arm crank ergometer is suitable for measuring physical fitness in healthy people. We expect that disabled people can use this submaximal test on the arm crank ergometer for measuring their physical fitness, also.