|Elite one-sport swimmers get in the pool every
day, sometimes twice for 10,000 or more per day! For triathletes with two
other disciplines in addition to swimming this isn't going to happen. One
way to get more swim training effect is to use some type of dryland swim
simulation technique. Best of all is if this work can be done at home.
Weight workouts can be designed to build strength and endurance in the muscle groups that are swim-intensive. Two favorites are lat-pulldowns and tricep-pushdowns both of which can be done with the same machine. Lat-pulldowns ar similar to the pull which is the first half of the stroke, and tricep-pushdowns are similar to the push which is the second half of the stroke. A good test of your strength is to see how many chin-ups and dips you can do unassisted.
Even more important than weights is core work. Holding a proper position as you swim requires good posture and core muscle strength. As you get faster and your form becomes more sophisticated, core strength can contribute to your speed with rotational motions where shoulders and hips twist independently at specific parts of the stroke.
You may have seen a "Vasa Trainer" at the pool. It's a simple device where you work against gravity by pulling yourself up an adjustable incline. You lay face down on a padded area that slides up and down on a rail while your hands are holding paddles attached to straps anchored at one end.
A simpler way to simulate a swim workout is with stretch cords. An elastic cord at least 10ft long is attached at its mid-point to an immoveable object. The cord has handles (preferably flat ones that you pull and push against with an open hand) and you pull exactly as you would in the pool. For recovery you do a negative instead of the relaxed high arm you'd have in the pool. With cords you can focus on arms only and perfect the motion to a degree that most athletes can't in the pool.
Cords travel well so you can use them anywhere. I've used them for swim warm up when I couldn't get in the water pre-race. At home I prefer a narrow bench to lay face down on. You can also do a cord workout standing, bent 90-degrees at the waist, but eventually your lower back will suffer. Make sure whatever the cords are attached to will not move, or worse, come loose (think sling-shot and doorknob)!