Your posterior muscles, the hamstrings, glutes, and the hips, contribute to hip extension and knee flexion and generate power when you run.  After a lengthy period of sitting at your desk, you finally stand up, get your favorite running clothes on, and go for your 10 mile run.  Your posterior muscles, mostly the hamstrings and the glutes, have been resting and either take their time getting involved with your run, or simply do not fire up at all.  This leaves your quadriceps and hip flexors, which are usually stronger than your hamstrings anyway, to do all of the work. Eventually the anterior leg becomes stronger while the posterior leg muscles become weaker in comparison.  After time, a possible muscular imbalance could occur, where too much quadricep strength on the front of the thigh and too little hamstring strength on the back, leads to muscle strains and even tears.  While the hamstrings are vitally important because they work to extend the hip joint and flex the knee, runners can suffer from injuries or limit mobility to these joints as well.
 
There are many ways to avoid this offset to our running: Warm up thoroughly before every run.  Shorten our running stride.  Try to run on a soft dirt or grass surface at least a few times a week.  Wear well-cushioned, supportive running shoes.  Learn to stretch properly.  Find a qualified personal trainer to assist you in finding appropriate posterior leg exercises.  Not only have all of these assisted me with my running since I was 14 years of age running cross-country for my Junior High School, I have actually never been injured or even had a single knee/joint issue that has taken away from my running.  Yes, I am knocking on wood right now (lololo).  Hamstrings are almost always weaker than quadriceps, but by strengthening them you will get better muscular balance.  Also, work to strengthen your core muscles (abdominals, glutes and adductors).  These muscles act as stabilizers for your pelvis.  Even if your running program is so long that it limits your time in the gym for other activities, get in that there at least 1 day a week to perform some exercises that really serve to strengthen and lengthen those pesky posterior muscles.
 
I mostly contribute this blessing of defeating any running injury so far, to the fact that I have consistently cross trained.  Besides strengthening my body through weight bearing activities, I also cross train through indoor cycling.  Yes, cycling is gentler on the joints and does assist with improving overall hamstring strength.  When your instructor tells you to increase the resistance until the heel drops on the push, and to pick up that heel and squeeze your hamstring with the pull back, listen to them. 
 
The CoreRippic with a side of Hams playlist was designed for an indoor cycling class that will not only wake up those resting posterior muscles, but also strengthen the entire core, thus improving your long distance running technique.  The overall 1 hour class will also leave that metabolism going for hours afterwards with the high intensity intervals that come from combining these large muscles (hamstrings, glutes, abdominals) into an intense energized cardiovascular class.

 
HIGH INTENSITY INTERVAL TRAINING (HIIT) IS FOUND TO INCREASE YOUR METABOLISM FOR 24 TO SOMETIMES 48 HOURS AFTER A WORKOUT, VERSUS SUSTAINED AEROBIC ACTIVITY LASTING FOR THE SAME AMOUNT OF TIME...HIGH INTENSITY INTERVAL TRAINING INVOLVES SHORTER INTERVALS OF MAXIMUM INTENSITY EXERCISE, FOLLOWED BY LONGER PERIODS OF LOW OR MODERATE INTENSITY EXERCISE...ALTHOUGH THIS KIND OF ANAEROBIC TRAINING THAT PUSHES YOUR BODY PAST YOUR LIMITS AT TIMES, CAN BE EXTREMELY VIGOROUS, YOU WILL NEED TO CONSULT WITH YOUR DOCTOR BEFORE ENTERING INTO THIS SUPER FAT BURNING, LEAN MUSCLE TISSUE BUILDING, TRAINING...

WHETHER YOU ARE PERFORMING AEROBIC EXERCISE FOR 20 MINUTES OR 60 MINUTES EVERY TIME YOU HIT THE GYM, YOUR HEART AND LUNGES WILL EVENTUALLY GET STRONGER AND STRONGER REQUIRING YOU TO PERFORM LONGER PERIODS OF AEROBIC EXERCISE WITH EACH SESSION FOR ADDITIONAL PHYSIOLOGICAL RESULTS...WHY??? BECAUSE YOUR BODY'S FAT BURNING SYSTEM BECOMES ADJUSTED TO THE WORK AND STOPS UTILIZING THOSE FAT STORES UNTIL A CHANGE IN YOUR WORKOUT OCCURS...DOES THIS MEAN THAT YOU HAVE TO DEVOTE EVEN LONGER HOURS AT THE GYM??? ABSOLUTELY NOT!!!  THIS CONSTANT INCREASE IN YOUR AEROBIC WORKOUTS WILL FORCE YOUR BODY TO EVENTUALLY GIVE WAY TO NOT ONLY BURNING FAT, BUT BURNING MUCH NEEDED LEAN MUSCLE TISSUE...THE FINAL RESULTS...A WEAKER METABOLISM...

THIS IS WHAT I HAVE BEEN TALKING ABOUT IN MY INDOOR CYCLING CLASSES...TODAY, FOR INSTANCE...MY STUDENTS AND I ROCKED THE HOUSE WITH MY INTERVAL X 4 WORKOUT...AFTER A SLOW AND STEADY WARM UP, WE PERFORMED 4 HIGH INTENSITY INTERVALS...ALL 4 STARTED ON A FLAT ROAD, THEN HIT THE MUDDY DITCH, FOLLOWED BY CLIMBING HILLS AND MOUNTAINS, AND ENDING WITH A STRONG SURGE UP THOSE SAME HILLS AND MOUNTAINS, UNTIL OUR ANAEROBIC THRESHOLD WAS UTILIZED...HOW DID WE MAINTAIN SUCH A VIGOROUS WORKOUT 4 TIMES??? THE FOCUS WAS ON MAKING THE RECOVERY PERIODS OF EACH INTERVAL JUST AS EFFECTIVE AS THE HIGH INTENSITY PERIODS...AFTER ALL, IF YOUR RECOVERY ALLOWS YOU TO GRAB ONTO MUCH NEEDED OXYGEN, THEN YOUR PERIODS OF HIGH ENERGY WORK WILL BE EASIER TO OBTAIN...IT TAKES APPROXIMATELY 5 CALORIES TO CONSUME ONE LITER OF OXYGEN...PLUS...HIGH INTENSITY INTERVAL TRAINING BUILDS LEAN MUSCLE TISSUE FASTER THAN STEADY STATE TRAINING BECAUSE, THE HARDER YOUR MUSCLES WORK, THE MORE OXYGEN YOUR MUSCLES REQUIRE...THAT BEING SAID,.DO NOT FEEL AS IF YOU CANNOT ATTEND THESE CLASSES IF YOU ARE ATTEMPTING CYCLING FOR THE FIRST TIME OR HAVE BEEN ADVISED NOT TO BY YOUR DOCTOR... HIIT IS NOT FOR EVERYONE... BUT, YOU CAN STILL PARTICIPATE IN THESE INDOOR CYCLING CLASSES BY MAKING THE APPROPRIATE ADJUSTMENTS TO YOUR TENSION AND SPEED AS YOUR INSTRUCTOR SHOULD BE FREQUENTLY ADVISING...MOST INDIVIDUALS THOUGH CAN DO A LOT MORE IN THESE CLASSES THAN THEY THINK....AND THEY DO...