Exercise movements, energy systems utilized, and training intensity must be closely paralleled by the training routine to derive the intended performance enhancements.
An example: swimming is a poor aerobic exercise to use to improve an athlete's
ability in running. The movements used in swimming are so far removed from
running that any training adaptation that occurs has little or no relevance
to bettering running speed, endurance or technique.
A more subtle example: good ski fitness demands that thigh stamina, for
instance, be highly developed. Quick sets of 6 to 10 reps won't cut it.
Yes, you want intensity, but you also must sustain exertion for longer than
5 to 30 seconds.
A great exercise mode by which, say, a sprinter may cross-train to improve
track performance is Olympic-Style weight lifting. On the surface these
two activities may not appear to relate too well to each otherafterall,
one is simply running, and the other is hoisting many pounds of steel overheadbut
that's not the case. The component that is the essence of both the sprinter's
and weight lifter's events is power: how quickly something (sprinter or
dead weight) can be moved from point A to point B. OIympic-style weight
lifters quickly accelerate the bar and plates up from the floor, and ultimately
to arms' length above them in a split second. This explosion of power from
the weightlifter's legs and hips, plus his / her ability to immediately summon
that energy burst translate very well to a sprinter's first steps off the
Just exercising isn't the key. Sport specific fitness and training is your
assurance that your efforts improve your sports and therefore your life.