This article summarizes previous studies on blood ammonia levels in relation to exercise. The dynamics of blood ammonia were reviewed with consideration to its production, removal, and distribution in various tissue compartments. During intense exercise, the primary source of ammonia is adenosine monophosphate deamination. Catabolism of branched-chain amino acids becomes important during submaximal exercise. Ammonia response to various types of exercise was also compared to lactate response. A comprehensive summary on factors affecting blood ammonia levels is provided. These reveal the possibility of applying blood ammonia measurement in monitoring and prescribing exercise, indirect measurement of muscle fiber composition, and muscle glycogen levels. However, more studies need to be conducted to evaluate these possibilities before blood ammonia measurement can be widely used.