While it is too early to tell how many athletes suffered injuries at this year's summer Olympics, statistics from the 2008 Beijing Olympics reveal that nearly 10 percent of participants suffered injuries. The most common injuries were ankle sprains and hamstring strains, but these were serious enough to prevent half of the injured athletes from competing.
On the heels of the very successful 2012 London Olympics, it is interesting to note that two of the most popular spectator sports posted increases in the number of injuries treated at US hospital emergency rooms in 2011 - soccer and volleyball. Using one's head in some sports is inevitable - take soccer for instance, where hitting the ball with one's head is the norm for Olympians and amateurs alike. In Head spark elite tennis racquet -medal match with Japan, both goals were scored by midfielder Carli Lloyd, with her first strike a header from 5 yards out. Lloyd had been subbing for Shannon Boxx who injured her hamstring in the opener against France.
The National Institute of Health cites that 4-8 percent of soccer players report suffering concussions, but theorize that 90 percent of concussions go unreported or unrecognized so the actual incidence may be closer to 40 percent. According to just released statistics from the US Consumer Product Safety Commission (CPSC), soccer posted an increase in the number of head injuries from 2010 to 2011 - with 24,426 and 26,726, respectively. The good news is that the overall injuries from soccer decreased from 226,142 in 2010 to 214,053 in 2011. According to CPSC statistics, 40 percent of soccer concussions are attributed to head to player contact; 10.3 percent are head to ground, goal post, wall, etc.; 12.6 percent are head to soccer ball, including accidents; and 37 percent are not specified. Inside Minnesota Soccer states that the following activities can lead to soccer head injuries:

Elbow to head and head-to-head contact when two or more players are contesting for ball in the air (most common).
Goalkeepers getting kicked or getting a knee to the head or hitting head on goalpost.
Body-to-body contact without direct contact to the head in which the head accelerates or decelerates violently.
Getting hit in the head unexpectedly with the ball and hitting head on ground after falling.
Deliberately heading the ball (least common).

Misty May-Treanor and Kerri Walsh Jennings won their third straight Olympic gold medal in beach volleyball, riveting the crowd with their physical and mental prowess on the sand. And while one cannot dive the same way on a hard indoor court, the US women's volleyball team was nearly as impressive, despite coming up short with a silver medal in the heartbreaking loss to Brazil. Team Captain Lindsey Berg injured her ankle in the game against Turkey.
Volleyball posted an increase in the number of head injuries from 2010 to 2011, with 3,481 in 2010 to 4,185 in 2011. Overall injuries from volleyball increased as well, but were not statistically significant - with 58,072 injuries in 2010 versus 58,803 in 2011. Of these injuries, an estimated 37,921 children under the age of 18 were treated for injuries in 2011, and 35,661 in 2010. Perhaps these injuries will spike in 2012 since the Olympics likely spurred a growing interest in the sport. The following statistics culled from an in-depth analysis revealed a clear gender inequity in volleyball-related injuries:

2011: Female: 39,083; Male: 19,720
2010: Female: 37,459; Male: 20,612

While bicycling was not among the most exciting spectator sports in the Olympics, it is a very popular recreational activity among people of all ages. As such, it is the recreational/sports activity that causes the highest number of injuries annually. The estimated number of bicycle-related injuries was 555,432 in 2011, and of these, 84,359 were head injuries. Among children 14 and younger there were 230,901 injuries. There are about 600 deaths a year, with two-thirds attributed to traumatic brain injury. It is estimated that up to 85 percent of head injuries can be prevented through proper usage of SNELL, American National Standards Institute (ANSI) or American Society for Testing and Materials (ASTM)-approved helmets. It is essential that the helmet fit properly so that it doesn't fall off while riding or if you take a fall. By taking a minute or two and using your head, you can help prevent potentially life-altering and tragic consequences. Many injuries are preventable by following simple safety precautions.
Biking Injury Prevention Tips

Buy and use a helmet approved by the American Society for Testing and Materials (ASTM) or Snell 100 percent of the time. The helmet must fit correctly and be worn properly to be effective.
Obey all traffic signals and be aware of drivers.
Do not text or talk on your cell phone while biking.
Avoid uneven or unpaved surfaces.
Wear bright colors when riding. If you must ride at dusk or night, wear clothing that reflects light. Install reflectors on the front and rear of your bike, and use a headlight.

General Sports Injury Prevention Tips

Supervise younger children at all times, and do not let them use sporting equipment or play sports unsuitable for their age.
Wear appropriate clothing for the sport.
Do not wear any clothing that can interfere with your vision.
Do not participate in sports when you are ill or very tired.
Obey all traffic signals, and be aware of drivers when cycling, skateboarding, or rollerblading.
Avoid uneven or unpaved surfaces when cycling, skateboarding, or rollerblading.
Perform regular safety checks of sports fields, playgrounds and equipment.
Discard and replace sporting equipment or protective gear that is damaged.