"265 sometimes happen. The most common injuries affect the musculoskeletal system (the bones, joints, muscles, ligaments, and tendons). Other adverse events can also occur during activity, such as overheating and dehyd ration. On rare occasions, people have heart attacks during activity. The good news is that scientific evidence strongly shows that physical activity is safe for almost everyone. Moreover, the health benefits of physical activity far outweigh the risks. Still, people may hesitate to become physically active because of concern they’ll get hurt. For these people, there is even more good news: They can take steps that are proven to reduce their risk of injury and adverse events. The Guidelines in this modul e provide advice to help people do physical activity safely. Most advice applies to people of all ages. Specific guidance for particular age groups and people with certain conditions is also provided. Physical Activity is Safe for Almost Everyone Most peop le are not likely to be injured when doing moderate - intensity activities in amounts that meet the Physical Activity Guidelines . However, injuries and other adverse events do sometimes happen. The most common problems are musculoskeletal injuries. Even so, studies show that only one such injury occurs for every 1,000 hours of walking for exercise, and fewer than four injuries occur for every 1,000 hours of running. Both physical fitness and total amount of physical activity affect risk of musculoskeletal inj uries. People who are physically fit have a lower risk of injury than people who are not. People who do more activity generally have a higher risk of injury than people who do less activity. To do physical activity safely and reduce risk of injuries and ot her adverse events, people should: • Understand the risks and yet be confident that physical activity is safe for almost everyone. • Choose to do types of physical activity that are appropriate for their current fitness level and health goals, because some ac tivities are safer than others. • Increase physical activity gradually over time whenever more activity is necessary to meet guidelines or health goals. Inactive people should “start low and go slow” by gradually increasing how often and how long activities are done. • Protect themselves by using appropriate gear and sports equipment, looking for safe environments, following rules and policies, and making sensible choices about when, where, and how to be active. • Be under the care of a health - care provider if th ey have chronic conditions or symptoms. People with chronic conditions and symptoms should consult their health - care provider about the types and amounts of activity appropriate for them. Choose Appropriate Types and Amounts of Activity People can reduce their risk of injury by choosing appropriate types of activity. The safest activities are moderate intensity and low impact, and don’t involve purposeful collision or"