When developing race read skills, the overriding goal is to learn to execute your skills in progressively more difficult situations, particularly situations that are relevant to the races you’d like to compete in. To do so, you need to put a premium on skillful swimming that is performed with high quality. With that in mind, simply design progressively more difficult training sets that resemble what you’ll need to do in a race.
Here are the rules for doing so.
Quality over quantity. You are better off performing less work that is performed really well, than more work that is performed poorly. Remember that skills come first, and it’s important to maintain a high standard of execution throughout all of your efforts. If you find that you are not swimming up to an acceptable standard, you are better off doing less to ensure that you are swimming up to your standards. 5 excellent repetitions are worth infinitely more than 20 sub-standard repetitions. Strive to ensure that you are practicing at a high level rather than simply practicing. This starts by designing practices that you can be successful with.
Work towards specificity. Over time, you want to be moving towards racing speeds and racing distances. Of course, you’ll never actually execute your race at race speed. For instance, if you’re racing an Ironman triathlon, you don’t need to complete the full race distance at race speed in a practice situation. However, you should incorporate aspects of race speed and race distance into your training moving closer to the final goal over time. The same would be true for someone swimming sprints.
Generally speaking, you’ll spend time racing shorter distances at or faster than race speed, and some longer distances that are slower than race speed. If you’re working on the longer side of it, you’ll aim to slowly increase the speed. If you’re working on the shorter end of it, you’ll aim to slowly increase the distance you’re swimming. This is how you work towards specificity.
Here's a sample progression, working towards a specific goal-
TARGET=1500m, all repetitions performed @1500m speed
1.15x100@30 seconds rest
2.15x100@15 seconds rest
3.5x(200+100)@30 seconds rest
4.3x(200+200+100)@30 seconds rest
5.3x500@30 seconds rest
Work above and below. Building on the previous point, there is a lot of value practicing slight slower (and longer) and slightly faster (and shorter) than your target. If you’re targeting an 1500-meter swim, you can perform some effort longer and slower efforts that are specific to a 3000-meter swim, as well as some shorter and faster swims that are specific to a 400-meter swim. This will help provide some variety to your training. Not only will this help you avoid boredom, it will help ensure that your skills are stable in a greater number of situations.
15x100@20 seconds rest; 1500m speed
6x500@30 seconds rest; best possible average
10x50@20 seconds rest; 400m speed
Keep it relevant. The goal when working faster and longer is to improve your skills in situations that matter to you. If you master the ability to maintain your skills during a 5-kilometer open water swim, it won’t necessarily help you in a 100 meter butterfly race in a pool, and vice versa. You need to practice in situations that will help you learn to sustain your skills in a manner you require in races.
You can swim significantly faster over shorter distances than you’ll ever race, or swim slower over longer distances than you’ll ever race*. However, doing so likely won’t bring you any closer to your goals as you’ll be working on executing skills in situations that you’ll never face in competition. It’s not relevant.
Now, everything doesn’t need to be ‘race-oriented’ to be relevant. For those competing in longer races (400m+), progressively longer and/or faster aerobic efforts are certainly relevant to your long-term development, even if these speeds are necessarily related to specific races. This is an example where the idea of ‘relevant’ can be fluid, and serves to remind you that you should be focused performing work that will move you closer to your goals.
FASTER. EASIER. BETTER.