This is a Fat Loss Challenge & NOT personalised coaching, so if you're carrying an injury it might be worthwhile consulting a doctor or medical professional before beginning, as following the training program might be difficult to do if you do have an injury. With that said, you'll have every opportunity to substitute any exercises you can't do from right within the smartphone app, using the substitution feature, however workouts will not be personalised any further than that should you come into the challenge with an existing injury.