When P and S waves hit the surface they transform into surface waves. P and S waves are signatures of fracture rock or earthquake. When a fracture occurs it sends energy out i â¦ n all directions. P, or primary wave is the initial large shock of the earthquake. This travels through anything.
Weekly Cardio Minimum. The Centers for Disease Control and Prevention recommend that all adults engage in at least 2 1/2 hours of moderate aerobic activity per week. If you do intense cardio, you can get away with half that time. You may spread your exercise over as many days of the week as you like, as long as each session lasts at least 10 minutes. In addition, the CDC recommends that all adults engage in some physical activity for 30 minutes a day, at least five days a week.
How Much Aerobic Exercise Should You Do? When considering the guidelines for aerobic exercise, keep the FITT principles in mind (Frequency, Intensity, Time and Type). Frequency: Number of aerobic exercise sessions per week Aim for a minimum of 3 days per week with no more than 2 days off between sessions.