Traditional methods used to estimate an individual's physical working capacity have at least one disadvantage in common, namely, the demand for expensive equipment such as cycle ergometers or treadmills. Consequently, the search for suitable tests performed in the field has been extensive. Most field tests do, however, require a maximal performance from the subject. The present investigation compared two special field tests, walking and running, both of a submaximal character, with (a) a treadmill run test and (b) a standardized cycle ergometer test. The comparisons were made to judge whether these field tests have the potential to replace or complement laboratory tests in certain situations, for example, when the purpose is to monitor training progress over time. Correlations were generally high and statistically significant within as well as between tests. Higher values were observed between field running and the laboratory tests than with field walking. This was true especially for the higher reference levels. Despite this, field walking may still be the best alternative for elderly persons or subjects recovering from injury, since the results indicate that walking, when performed intensely enough, gives a fairly good estimate of an individual's physical working capacity.