Let me set the scene for you. Your in the heat of a swim practice. Your the coach and you've written a set, a set where you dreamed that all the swimmers could work on their stroke (non-freestyle). It all seemed perfect in your head. You made it "choice", because you're smart and you know that the swimmers will be more motivated if they have some autonomy over what they do.
Except they all chose backstroke. "YOU CAN'T ALL BE BACKSTROKERS!" you scream, either internally or out loud. You look at lane two. There is Agatha. She complained to you last meet about how "we never train breaststroke". And she's swimming backstroke. Your blood starts to boil.
Take a deep breath. Count to ten if you need to. Here are some reasons why your swimmers might be making this choice, and what you can do about it.
1. They might be backstrokers- Have pity on them for being the most inferior sect of swimmers. Shots fired Garrett McCaffrey.
2. The sendoffs could be wrong- One of the biggest rookie mistakes in constructing practice is to assign a single interval time for all three strokes as if they are equal. Backstroke and butterfly are much faster than breaststroke by an order of 3-4 seconds per 50m on the elite level.
Also, if you are not training race pace (why aren't you training race pace?), then backstroke will be much easier to do at below race pace, for longer distances.
Swimmers instincts to avoid butterfly and breaststroke when sendoffs do not allow them to do the reps at quality are correct. Common technical problems in these two strokes are a result of "struggle" technique when forced to do repetitions with inadequate recovery or too long distances.
If I were designing a race pace set of 25s for butterflyers, backstrokers and breaststrokers to all do together, it might look something like this:
30x25 on :30/:35/:40
Backstrokers able to go under 1:00 should start on the :30. Backstrokers 1:00-:1:12 on :35. Breaststrokers up to 1:00 on :35, Breaststrokers up to 1:12 on :40. Butterflyers up to 1:00 on :35, up to 1:12 on :40
Any butterflyers or breaststrokers who struggle to string more than a few together at 100 pace, you could consider adding 1 sec to their 100 pace, focus on efficiency, or making every 4th one "easy"
3. Your swimmers are scared- Do you know the theory of learned helplessness? It's really important to understanding why people don't do things that would benefit them. Training hard, particularly in breaststroke and butterfly, is painful.
As a coach, you need to build a bridge between this painful training and results. If your swimmers are scared and avoiding it, it is because they don't see the bridge. Yelling at them may scare them enough to take the leap, but will ultimately just be adding another painful thing to avoid.
Have empathy for your athletes, and connect with them on the level they are on. Figure out at what level they will be willing to risk themselves, let them go there and make sure they see the progress that results.
4. Their backstroke technique is poor- I thought of backstroke as an easy stroke when I was a swimmer. Why? Because my backstroke technique was terribly.
Specifically, I barely kicked when swimming backstroke. Kick is the most obvious thing that all coaches want swimmers to do, but much like breaststroke and butterfly, it makes things much more painful. But much like an appropriate risk in butterfly and breaststroke, this pain brings better results.
If swimmers are going to insist on swimming backstroke, you need to insist that they maintain a steady, narrow kick. Don't allow backstroke techniques that make the stroke "easy".
If you've tried all of the above and your swimmers still insist on swimming backstroke, don't give up hope. Someday, they may grow up to win an NBA title.