Q:

Exercises with a Torn Wrist Tendon

For the past month, I noticed that I developed about a 1/2 inch size lump on my left inner wrist.  I suspected it was a cyst, but after seeing the hand surgeon I was told that I have a torn Flexor carpi radialis (FCR).
The doctor gave two options:

8 weeks in splint or
8 weeks in cast

I am pretty active with cardio (running, plyo) and weights but I am trying to determine the best option. No matter the choice I make, I want to still work out.  
What are my options with this type of injury?  Are there any strength training, cardio choices with this type of wrist injury?  
Just as a side note, any thoughts on cast or splint?

A:

Just curious, why was surgery to repair the tendon not an option?
As far as working out, I wouldn't worry about that too much, because that's a short term thing, unless you have a specific event (Your 'A' race for the season or something) that you are training for.
8 weeks is transitory, and yes, you might lose some fitness or a bit of muscle size during that time, but compared to a lifetime of activity, it's nothing. Whichever option gives you the BEST chance to get back to normal activity for the long term is the one that I would go with.
Just as a personal example: I've been a competitive athlete since I was 4 (40ish years), and was in the middle of the current triathlon season, and ruptured my achilles in martial arts class 6 weeks ago. I had the option of either cast only, and letting it knit on it's own, or surgery to repair. The surgery was a longer rehab, more inactivity, but it gives me the best option to return to full, normal activity.
So, figure out which option gives you the best chance to get back to normal, do that, and deal with the minor losses that you will have in 8 weeks.

