This subject has been covered in the past, so I will keep it as simple as possible. This device is not for everyone. Personally I know a few individuals who do use these masks for their training, but they don’t have the same effects for all them. I agree with Christine that there are better ways for him to increase his aerobic (and anaerobic) capacity. Hiring a fitness professional to design a constructive and effective training plan for him might be the best choice here.