There's a lot you can do with bands or elastic tubing that doesn't take long and can give you an edge. Core work and cross training such as the more endurance-based forms of CrossFit can help you build up the strength you need to make gains in the water.
More: Strength Training Circuit for Triathletes
However, if you are still working on your form, you may want to put off strength training.
Increase Your Interval
You won't start swimming faster unless you gradually increase your intervals.
Many get stuck on the idea that they will always be a certain level of swimmer. In masters swimming, you start to get used to your lane mates, and it may be tough to move on. Start by going to a faster lane once a week. Then move that up to twice, then three times when you're ready.
Play a Game
This tool can help you create a more efficient and faster freestyle. Begin by completing 10 sets of 50 yards. Count your strokes and get your time on each one. Add those two numbers together to get your "score."
For each "round", attempt to lower that score by focusing on high elbow pulling, extending your arms, or increasing your effort. Do as many 50s until you can't go any lower. For a more advanced version, try not kicking or put a band around your feet.
Remember, take one thing at a time, never sacrifice technique in the effort to go faster, and start watching your times drop.
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