Deep water running is one of the things that injured runners always talk about, but are never eager to do (just like cross training on bikes). It can be deathly boring and extreemly tiring, two factors that make this a debatable workout choice for injured runners. I however, have found a few ways to make deep water running more interesting and provide a solid workout while I am injured.
Tip #1: Don't use a foam water running belt
True water running does not constitute the use of a floating device while you run. You are not signing up for your grandma's aquafitness class (no offence to my grandma who is a committed blog reader). You are performing the running motions under the water, and are activating the glut muscles when you pull back through the water. Not wearing a belt will get your heart rate much higher, and lead to a better overall workout. If you feel like you might drown, hold onto the edge and practice the leg motions.
Tip #2: Don't use your arms to keep you floating
Now that you are in the deep end without a foam belt, you need to use your legs to keep you up, not your arms. Tuck in the elbows, and keep the arms bent at 90 degrees, making a fist with your hands. Save your arm muscles for the swimming workout, and focus on glut activation and proper technique with the legs. The motion is like doing high knees, kicking out the lower leg, and then pulling back with the foot facing the bottom of the pool (like B's for you runners). By eliminating excessive hand motions, you will help eliminate sloppy form and will get better leg motion and activation.
Tip #3: Don't lean forward
More often then not, you will find yourself leaning too far foreward when you water run (especially you cyclists). This may help you go faster down the pool, but that is not the goal. Water running is meant to provide fitness, but also provide an oppurtunity to focus on good technique. Good runners will not be hunched over when they run, and this should also be the case in water running. Focus on having a straight back, with the shoulders relaxed and pulled back. The shoulders should be in line with the pelvis, and the feet should pass directly under your perfectly straight upper body.
Tip #4: Find someone to run with
When I was just starting out with water running, I was helped out by some of the veteran members of my XC team, who were also injured and experienced water runners. We also had our coach watching us from the side of the pool, giving us tips on our form, and timing us for intervals. Watching someone who has good water running form in person can help boost your own technique, and make you much more relaxed in the water. Having someone to run with also helps eliminate boredom and helps the time to go by much faster (My 50 minute run today went by really fast since I was talking to my water running partner the whole time. Also having a few female french exchange students wearing bikinis come into the slow lane helped keep things interesting....)
I have no idea whether water running will help with my actual running when I slip the shoes back on. I find that my water running workouts are very difficult and surprisingly fatiguing. During intervals, I can get my heart rate to around 160-170 BPM, but usually hover in the 120-130 range. My legs definatly feel the fatigue of water runs, but at the same time, it is also very easy on the joints, so it is a good workout for injured runners (or those who don't like the pounding). If you are thinking about starting a bit of water running, do it in combination with a swim workout. This way you could do a workout where you feel comfortable, and then move on to a totally different workout. My first few attempts at water running were far from pretty, but I stuck to it, and my form has improved significantly (and my enjoyment).