If you are new to running you definitely want to be wary of developing runner's knee [1], an overuse injury that is twice as likely to occur in women than men. Known in the medical world as patellofemoral pain syndrome (PPFS), runner's knee causes pain in and around the knee cap (or patella). The pain is caused by tracking issues with the knee cap that irritate the bony groove the knee cap actually sits in. While there can be many reasons for this annoying and common problem that most often strikes newbies, it is most often caused by tight hamstrings and calves (the muscles in the back of the leg) coupled with weak quads (the muscle at the front of the thigh).

You don't need to avoid running to prevent runner's knee, but you should try to run on accommodating surfaces like dirt paths and asphalt, not concrete. Uneven terrain and hills can aggravate knee tracking problems, so be wary of hills if you are experiencing tenderness around your knee caps. Be proactive and strengthen your quads. And to see how, just .

Wall sits are an easy exercise that target the quads.

• Stand with your back against a wall, placing your feet about two feet out in front of you. Feet should be hips distance apart.
• Bending your knees, slide your back down the wall until your knees are at 90 degree angles. Your knee joints should be over your ankle joints, so you may need to inch your feet further from the wall to create proper alignment. Don't let your knees fall in on the midline of your body, or sway outwards.
• Hold for one minute, do three reps.

Don't forget to stretch your hamstrings [2] and your calves [3] too.

Source [4]