Thank you for using the Jiskha Homework Help Forum. Since you ask 3 questions, let's look at the first one first:
The physical condition of someone will influence participation. For example, an obese child either will not want to participate or will be unable to participate. Here are some sites:
Note: Culture could also be a factor.
How participation is encouraged:
1. (Broken Link Removed)
Note: Many articles require trying a service but they suggest government must take a role, although they don't say how. The price of sports (expensive equipment, for example) can eliminate many.
4 key issues & impact
2. (Broken Link Removed)
Note: Because of budget cut-backs, many schools have deleted physical fitness (gym) in the curriculum. Therefore as extra-curricular, the ones involved in sports must bear the brunt of the expense = purchasing equipment, uniforms, etc.