I'm a member of a competitive (Master's) rowing team and a former bodybuilder (20 years). My coach recently announced that as a team, we need to spend more time (six to seven days per week, 45 minutes per session) training on the indoor rower during our winter training for the next 4 months. With my history in strength training, I'm a bit concerned that this amount of exercise volume affords little time for recovery. Does anyone have references to the effects of exercise volume on recovery? It's my belief that this new requirement may not be optimum for 50+ year old athletes looking to improve without experiencing long term injuries. I should also add that we are expected to perform strength training with weights as part of our conditioning.
With an indoor rower, it's going to be much the same as cycling on a trainer or swimming. They will all be low impact, so presuming that you have a history of endurance training, you shouldn't have a problem adding in the 45 minute workouts 6-7 days a week.
The two things that really affect recovery are impact and intensity. Since you are on an indoor rower, impact is negligible, so you would just need to watch intensity. I would structure it much the same as an endurance running program, to where the majority of your time on the trainer is spent at stead state to increase your endurance, and 2-3 times a week throw in some more up tempo, higher intensity rowing for brief periods during the workout. (Such as 45 mins, 15 minutes build from easy to moderate pace, 5-8 minutes of :30 sprint, :30 recovery, 20 minutes zone 3 (on the lighter side of moderate), 5 minutes cooldown.)
Along with this, nutrition and getting your muscles refueled will be important, so be sure to keep a healthy diet.
If you are expected to do weights as well, I would suggest (if possible) that on the days you do both workouts, you split them apart. I would also try to not do a really high intensity workout either same day or day after weights.