Tempo Training and SPL at Faster Tempos

Based on my coach’s suggestion, on the next workout I decided to swim at a higher tempo settings.
After warming up, I set my tempo trainer at 1.6 seconds, swam 4×25, then lowered my tempo by .1 seconds, swam another 4×25, until I got to 1.2 seconds tempo where I determined my comfort breakpoint usually is.
Here are my results:
1.6 seconds, SPL: 13, 12, 12, 12
1.5 seconds, SPL: 4×12
1.4 seconds, SPL: 4×13
1.3 seconds, SPL: 4×13
1.2 seconds, SPL: 13, 13, 13, 14
Once I started getting tired at 1.2 seconds, I drifted to 14 SPL and stopped, knowing I would probably get frustrated with trying to keep my SPL with rising fatigue.
At my next workout, I decided to go even faster. My coach tells me that sprinting tempo is around .8-.9 seconds. I wanted to see what that felt like and whether I could even keep up a decent form. Starting from 1.6 seconds tempo to give myself a bit of warmup, I did 2×25 at each tempo setting until I got .8 seconds.
Here are my results:
1.6 seconds, SPL: 13 12
1.4 seconds, SPL: 13 13
1.2 seconds, SPL: 14 14
1.1 seconds, SPL: 15 15
1.0 seconds, SPL: 16 16
0.9 seconds, SPL: 17 16
0.8 seconds, SPL: 17 17
The fast tempos are too fast for me at this point. My body coordination to stroke, body turn, and kick, as well as breathing at that tempo is a bit too difficult to maintain right now. I also found that I could not maintain my stroking force as well as when my tempo is slower. In order to maintain tempo, I have to reduce my force and just get used to cycling my arms at that speed.
Computation of speed to complete a 25y length is, using my coach’s formula:
1.2 seconds @ 14 SPL: 20.4 seconds
1.1 seconds @ 15 SPL: 19.8 seconds
1.0 seconds @ 16 SPL: 19 seconds
0.9 seconds @ 17 SPL: 18 seconds
0.8 seconds @ 17 SPL: 16 seconds
One of these workouts, I have to time myself to see how accurate these time computations really are.
Observations:
1. I think that I did not “spin” and that I was actually gliding a bit with each stroke. But it was harder to see this effect at the higher speed.
2. I need to find a way to maintain force at higher tempos. To maintain that force is very difficult for me now and also cycle fast.
3. My coach told me that when you cycle faster, you need to stroke shorter, lifting your arm out of the water sooner. Also, everything is happening faster so I have to get used to doing the whole swim movements faster and precisely. At the same time, I need to be as relaxed as when I was swimming with slower tempo. Tensing up just makes me slower and more tired.
4. Like with running, I am going to start neuromuscular training for swimming. I think I will add in a training session where I am just swimming at fast tempo, but not necessarily caring what my SPL is.