As it's relevant to the sport I practice and just came back from armwrestling training I'd like to randomly comment: Armwrestling clubs have a LOT of people with tendon pain and injuries. The general approach to recovery and building tendon strength (beside lifting heavy) is to do static holds of 10 seconds+ of light to medium weight. Often paired with very large sets (50+ reps) of _extremely light_ weight; lifting almost nothing, just to get the blood through the tendon. You should not feel sore at all in either movement. The idea being that blood gets into tendons through movement. As for static holds; tendons expand during these static holds, so the idea is that they can then absorb more nutrients... Or something like that; I'm no expert by any means!

In the bouldering community there has also been a bit of an uproar where Emil Abrahammsson (find it on Youtube) did very light static holds 2+ times per day for ~30 seconds if I recall correctly for great tendon strength, this also had some influence on how people train for armwrestling. This style was nicknamed "Abrahangs".