Busy at the Fitness Health camp today, doing a little bit of core work. The standing twist is a great exercise that gets the core and back muscles working well. This exercise will activate your abdominals and obliques muscles. Completing this exercise with a 5 kg medicine ball is definitely challenging. I would recommend reducing the weight if you're doing this exercise for the first time. I completed 3 sets of 10 reps on the exercise above. Pick a side for example your right side, then every time you twist to your right this counts as one complete rep.