Long runs, long bike rides, or just overloading with weight training can cause tightness in the back muscles and make you feel real stiff and unable to move. Usually this can be remedied with some recovery stretches and some foam rolling.
Do this at least once a day. You can do them two or even three times a day if your feeling very stiff.
1. Open up the hip flexors
A couple of ways to stretch the hip flexors.
One way is to use your foam roller. Exercise demo is shown below.
Another way is the kneeling hip flexor stretch.
2. Foam roll and stretch the TFL
foam roller and sea saw back and forth on the TFL. Find a tight spot and hold it for about 20 seconds.