Many coaches claim that they don't use bodybuilding concepts like isolation exercises because they don't want their athletes to become overly muscle-bound and less athletic... the way they perceive many bodybuilders. This view is out of touch with reality.
Doing some hamstring curls and triceps extensions won't automatically turn you into a pro bodybuilder any more than doing sprints on a track turns you into an Olympic sprinter. Nor is the central nervous system so fragile that performing a few sets of isolation exercises or a few sets on weight machines could somehow undercut the functional abilities and movement skills acquired from long hours of sport practice and competition.
Improving your sports performance from training isn't purely related to gains in strength. They can also be related to increased bodyweight from muscle size. So, building your body actually can help you improve your overall athletic performance.
In fact, one of the things that determines our stability and strength from our feet is bodyweight. A body's mass (or weight) contributes to stability because heavier bodies are harder to move and hence are more stable. On the flipside, lighter bodies are moved more easily and are less stable (1).
So, getting bigger can help you better use your strength by providing a greater platform from which to push against your opposition. It can also give you a better chance of avoid getting knocked over or knocked off balance.
The Bottom Line
Getting bigger by putting on 20 pounds of muscle mass (not fat) through hypertrophy training can help you better use your strength by providing a greater platform from which to create and resist force.
- William C. Whiting, and Stuart Rugg. Dynatomy: Dynamic Human Anatomy. Human Kinetics 2006. Taken from Human Kinetics website.