SnappingT wrote:
The overwhelming, governing variable that triathletes should be aware of is the less amount of time you swim, the harder and more intense the swims you do need to be.
Swimming is very technically driven that's why there is so much practice involved. The brain and body need about 15 - 20 minutes of focused warm up to warm up. If you don't give it that much time, you'll just be warming up during the part of the practice when you are trying to drive adaptation.
The brain likes variety. Change up the sets you are doing. Vary the distance, although I would probably keep the repeats 150 or less. Vary the amount of rest you get. Use gear to "constrain" aspects of your stroke to drive technique and fitness improvements at the same time.
At some point, you'll have to contend with the reality of the distance and the demands of the discipline. Two times a week for 40 minutes isn't enough training for a 1.2 mile (1900m) swim.
You might be able to get through it, but you'll be robbing fitness from the bike and run to do it.
I hope this helps.
Tim
Everything he said.
I also BET that you don't just have 2x40min slots. You are LIKELY only choosing to do 2x40min, because you prefer to bike and run with the rest of the time slots. But look what happened to Lucy Charles when she could not run and she put all her run + swim volume into swim+swim volume and ended up on 50km weeks. Suddely here Kona leading swim pace was easy enough to have a record setting bike and run day.
I know you said 2x40 min, but as it is not tri season in the north hemisphere, consider if you can just ditch the trainer hours and replace them all with swim+commute to pool hours (if possible, but maybe pool times don't align). You could literally miss months of biking and if you replace with swimming you won't lose anything getting back on the bike and the technical gains will be there with you more or less for life.