This thesis incorporates four related studies which examine the ability of school-children (aged 7-11 years) to utilize the psycho-physical concept of perceived exertion (or effort perception) during cycling exercise. Previous research in this area had been promising, but afflicted by notable methodological limitations, such as the use of the adult-specific Rating of Perceived Exertion (RPE) scale as the principal investigative tool, and rather vague forms of data analyses, meant that new research was merited. Accordingly, the present investigations set out to assess both the performance of the recently developed Children's Effort Rating Table (CERT) and clarify the appropriate method of analysis for studies of this kind. The key outcomes of the current research were that: (i) when asked to express their overall feelings of exertion during incremental cycling exercise, the children's responses with either the CERT or the RPE scale correlated fairly well with objective indicators of physical exertion - heart rate and power output. Used in this estimation mode, the CERT appeared to be superior. (ii) When asked to manipulate the exercise loading to match specific perceived exertion levels the objective-subjective intensity associations were, whilst significant, less impressive. In this production mode, the children seemed not to be able to use the CERT any better than the RPE scale. (iii) Procedural aspects of testing, such as the temporal nature of the exercise protocols, can influence the responses given, and subsequent interpretations. More precisely, the children were better able to use the CERT in production mode when the exercise was discontinuous than continuous. Further work with the CERT amongst children of different ages, involving exercise of different kinds and occurring in different environments, is now encourage