when walking down stairs or a steep hill, the knee is flexed. which structure prevents the tibia from sliding too far posteriorly, and the femur from sliding too far anteriorly?

If a woman exercises 25 minutes each day, which is true, according to physical activity recommendations? a. she is exercising too much. b. she is exercising too little. c. she is exercising enough. d. it depends on the woman's level of activity.