Yes, these are going to be safe to wear while engaging in cardio activities, but as long as you keep a few things in mind. Adding additional pounds is also going to increase your risk of injury. There are, however, a few ways to sidestep this issue. The first way is to ensure that you never go too heavy. It might seem tempting to push it as heavy as you can go to build the most about of muscle and endurance, but this is exactly where people run into injuries. The second thing that you want to consider is that you ensure that it isn’t going to affect your natural gait. You have most likely spent a long time developing a gait that feels natural and tries to distribute the impact of hitting the ground evenly through your body. When you add too much weight that disrupts that natural process, vulnerable parts of your body (such as your knees and lower back) are going to be more susceptible to injury.