There's a series of exercises in
Going Long by Friel and Byrn that are good. (The book is otherwise mediocre but if you're new to IM training, for example, it's not bad reading at all).
Tubing (what she calls working out with dryland swim cords) is a significant component of Sheila Taormina's
Swim Speed Workouts (and are described in her book
Swim Speed Secrets). I most highly recommend both.
If you google Sheila Taormina tubing, lot of great videos, drills, ideas.
Also, don't underestimate what you can accomplish in a small hotel pool with a swim bungee system (like Aquavee).
Once you figure out how to correctly transfer the parts of the swim stroke to the swim tubing, putting workouts together is fairly easy. This is generally what I do if I'm not going to swim on a particular day--either 2x20 min or 1 30-min session.
1-2 min or 3-5 sets of 8-10 reps each of catch, then pull, then push phase (what Sheila T calls diagonal), then finish, then 1-4 minutes of full stroking. Rinse, repeat.
This can also be done very effectively as butterfly (both arms at once) and I've found it transfers very well to actual freestyle swimming in water.
Yanti Ardie of Y Tri Multisport & Majick Juice for lasting critter defense & skin soothing
~ World Open Water Swimming Association Coach & Official
~ IRONMAN Certified Coach (Founding Member)
~ Triathlon Australia Professional Development Coach
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