Pappy - 5 mi swimming seems like a lot. Keep it up
Smoove - Good luck in Houston
slow jogger - Welcome to the thread!
misser - Good luck on your racing
RRR - You didn't ask for this but here it is anyways
Hopefully this link works - if it doesn't let me know. Here is my hamstring injury story
In winter 2014 I was in the best shape of my life. I was overdoing it in training so I only ran 9:24 3k, 1:29 600 and a 55 400, but one workout was
4x800 w/ 3 min jog (2:26, 2:26, 2:24, 2:21) 6 min jog. 4x400 w/ 2 min jog (69.4, 69.0, 67.1, 62.9) 6 min jog. 2x200 (29.9, 29.6)
A week later I felt a twinge in my hamstring on the last rep of a workout but cooled down fine. The next day I could hardly walk. I ended up taking 3 months off of running and another 3 months without serious training (if you dig back through old threads you can find me posting 5-15 mpw). First race back was a 40 min 10k and its been mostly up with a few downs since.
The things that I've had the most success with are nothing ground breaking and aren't an overnight fix but when I've gotten away from them I've had soreness come back.
warm up - yoga (child's pose, cat-cow, hip circles, 2 sun salutations not hold the positions for long), 10-20 min running, leg swings, skipping, shuffling, carioca, A/B/C drills. If my hamstrings are sore/tight I will do extra B drills, hips A drills, knees C drills
strength - 1 leg bodyweight movements, (lunges, deadlifts, step ups, squats). I start and end my strength sessions with bodyweight movements and I also do a small circuit with ~20 reps per leg every night. The nightly circuit is more for mobility but I'm sure over time it builds strength. I also clean, squat, etc w/ a barbell but I don't know of these do much for injury prevention.
stretching - Every night I do ~10 min of static stretching before I go to bed.
sprinting - I keep a healthy smattering of hill & flat sprints in my training. Started out with 4x10" hill sprints and have slowly added volume and flat sprints throughout the years. I really believe that keeping in sprinting year round helps prevent injuries.
Short version - I hurt my hamstring pretty badly and I'm still bitter about it ;)