5 rounds of underwater swim 25 yrds + 50 air squats for time Workout

REHAB #6: still nursing my lower back pull
Five rounds for time of:
Underwater swim 25 yards
50 Squats
You can't swim at all above the water.. whenever you pop up you must not continue on horizontally. Pop back down and continue.. take as many stops as required and as much time as required.
I felt pretty good overall. I did not go out all guns ablazing and the back felt pretty good on the higher rep air squats. I was going FULL ROM for almost every rep.
For me the most time by far was spent on the air squats. Each swim didn't varry too much. The air squats were taxing though. Felt it in my quads a bit.
I did a warm up for about 20 minutes and then went down and just did the workout in about 10 minutes.. maybe a few seconds less.
Good WOD.
I took a steam, streatched out in there and then a long hot shower.
I'm still going to take it a little easy but add weights and slowly ramp back up.