Many muscular/skeletal problems and injuries especially in adults can be attributed to a lack of

flexibility

Explanation:

Stretching may help prevent injury according to many doctors. Stretching improves your flexibility. "A sports medicine physician will determine your level of flexibility and form an activity or exercise prescription with specific exercises and stretches to improve your flexibility." This shows that your level of flexibility contributes to what activities you can do without injury.

halogen, any of the six nonmetallic elements that constitute group 17 (group viia) of the periodic table. the halogen elements are fluorine (f), chlorine (cl), bromine (br), iodine (i), astatine (at), and tennessine (ts).