Hello,
This is just my one and a half cents...
1) A good way to cross train, not the best for increasing paddling stamina because it isn't entirely sport specific. Keeps things interesting though, and is worth a couple hours per week of your time. If you do choose to run, choose higher intensity interval over LSD (it better emulates our paddling style, which I assume is dragonboat, which is short power-endurance pieces)
2) Excellent to create or maintain an aerobic base, and capillarize your muscles. This makes it easier for your muscles to receive blood/oxygen and release wastes. This definitely increases endurance. Assuming you have relatively high endurance, 5k shouldn't be a big problem for you.
3) The best for building power-endurance, which is essentially our sport (again I'm assuming DB, not OC) the numbers are different depending on what you're looking for.
- Speed: 15x (10s on @ 100%, 60s easy paddle @ 60%, or starts up to the transition)
- Absolute power: 8-12x (10 of your hardest strokes, 1-2 minutes rest)
- Endurance: 3x (10min on/2min off)
- Power-Endurance: 6x (30s on/15s off/45s on/30s off/30s on @ 85%, 1-3 min rest) then working up to longer pieces at a higher intensity with similar rest. For example, if you are training for the 200m races, you wouldn't go up to 2 minutes of work (it takes about 60s to do 200m on a DB). Then, if you are training for 500m races, you wouldn't stop at just 90s of work (because it takes approx 2min to do 500m on a DB). Bottom line is, if you have a goal distance in mind, use that when creating your workout pieces. Stretch out the pieces by a little bit once in a while.
Eg. power endurance pieces for training for 500m, if your team normally does about 2:10
**Remember this is just an example and you can move it around according to you/your team's abilities and current speed.
**This pattern also shouldn't be the only thing you are doing on a DB/OC... power endurance is just one of the aspects of training.
Beginning of season:
8x ([5x
30s on/30s off] @ 85%, 1-3 min rest) = total work 2:30
Midseason:
6x ([
45s on/30s off/
60s on/30s off/
45s on] @ 90%, 1-3 min rest) = total work 2:30
Near regatta season:
4x ([
60s on/30s off/
30s on/30s off/
60s on] @ 95%, 1-3 min rest) = total work 2:30
Regatta season:
4x ([
75s on/30s easy/
75s on] @ 100% or race pace, 1-3min rest) = total work 2:30
or
2-3x 500m (and time it for fun)
There's not really a set limit you have before overworking yourself. Your body doesn't say to itself "I will get hurt at 7km. 6.8km should be alright" just read your body and don't push yourself to injury. Your body's status and limits change weekly, daily, hourly. Tomorrow is always another day to try again. Stop when you need to, push yourself when you are able to, but just don't be dumb about it

For intervals, again there isn't really a "safe" number. What you can do, though, is balance the pieces. What I mean is, the longer your piece, the lower the number of sets. For 3min on/3min off, I would do about 8 of those. If I shortened it to 1min on/1min off, I may do 15 of those. The amount of rest also denotes how many sets to do. (see above)
I'm a huge fan of interval training because you get to work your body at a higher intensity, burn the same number of calories as you would doing LSD, it's more interesting and fun, and you literally get fitter, faster.
You're overworking if:
- You consistently look and feel like crap during a piece (means it's too long or too intense for you at that time)
- Your technique goes down the drain all of a sudden
- You have pain/inflammation in your joints. Don't grin and bear it... stop immediately.
You're not necessarily overworking if:
- Your technique remains relatively the same throughout the piece, aside from sprints, where most people's techniques die fast
- You feel a burn in your muscles during a piece, that's just lactic acid
- You feel sore afterwards
You may burn out if:
- You paddle too often, suddenly (going from 2x/week to 6x/week within 2 weeks)
- You paddle too long, suddenly (going from 2k at a time to 5-8k)
- You begin to dislike the feeling of going on an OC but still push yourself to do so, for some reason unknown (my situation)
If you are eager to improve and get results, you are actually better off making yourself rest at least twice a week. So, two full OFF days per week... meaning no hard training. You can still go for a light jog on your off days, but no paddling. It will keep your muscles from hating you and it'll prevent you from hating the sport. Trust me on this one... I wish I stopped when I could.

Sorry for talking so much... I really like exercise physiology
