Cross training is a term that has gained fairly wide acceptance in training the last fifteen years as a means of raising work capacity. Cross Training “… is when an athlete undertakes training in a discipline other than their main sport for the sole purpose of enhancing performance in their primary event.” (Hawley & Burke P. 31) The origin of the term probably lies with the first triathletes. It has been primarily used as a method for retaining training adaptations when injured, but has also been used as a supplementary training method to raise work capacity. What we must be aware of is transfer of training effect. It has been my experience that those who utilize cross training are those who already have a tendency to chronically overwork and are looking for another way to add more work. The concept of “cross training” is another training myth that has actually detracted from sound training. It certainly has very little foundation is sports science research. For a runner to get in the pool for anything more than a recovery session is time ill spent. The same is true for biking for a runner, that time would be better spent strength training or working on flexibility, both areas that tend to be ignored because the runner feels they do not have enough time to fit them into the overall training. Yet those same runners can find the time to swim for thirty minutes or bike for an hour. It is all a matter of priorities. Research does seem to indicate that there is more transfer of training effect from cycling to running than from running to cycling. Cross training can be beneficial for the recreational athlete seeking to raise general fitness or relieve the boredom of training, but for the high level athlete the returns are not commensurate with the time invested. “Specific exercise elicits specific adaptations, creating specific training effects.” (McArdle, Katch, & Katch P.394) Loy et al in their excellent review article “Benefits and Practical Use of Cross-Training in Sports” sum up the value from a research perspective “For performance and aerobic benefit, cross training with dissimilar modes would be effective for participants with lower aerobic capacity. The more highly trained individuals will profit more from similar-mode cross-training. Within each fitness level, the studies suggest that the higher the aerobic capacity, the smaller the relative improvement from cross training.” (Loy et al p.6 1995) Remember a good sound comprehensive training program will incorporate variety of means to achieve various training goals.