It is estimated that as many as 50% of individuals initiating an exercise program will report an injury within the first six months. These injuries make it difficult, if not impossible, to continue physical fitness training without some layoff period. Many risk factors for injury have been identified and are listed below (along with some risk reduction strategies):

• Inflexibility & muscle imbalances
  Joint mechanics are disrupted when muscles on one side are excessively weak and/or lengthened while muscles on the other side are overdeveloped and/or tight. Train in a way that promotes muscular balance from front-to-back, side-to-side, and top-to-bottom. Stretch the tight muscles and strengthen the weak muscles.
• Environmental considerations
  Running on harsh surfaces (i.e., uneven terrain, banked surfaces, concrete) can magnify the stress placed the musculoskeletal system. Opt for relatively flat, cushioned training surfaces when possible. Harsh climates can also lead to heat or cold illness, so acclimate yourself with 10-14 days of moderate training in the environment.
• Faulty equipment
  Choose footwear that is appropriate for your activities and allows for normal mechanics, especially during running. Replace your running shoes after 300 miles or every 6 months.
• Overtraining
  Too much physical stress applied too quickly with insufficient recovery can lead to dysfunction. Adhere to the physical training guidelines addressed here and those set forth by leading fitness and sports medicine organizations.
• Improper technique
  Faulty exercise technique can place undue stress on joints and soft tissues. Never sacrifice form and technique for more repetitions or faster times.