The 28-day program—created by Nike master trainer and functional strength coach Alex Silver-Fagan, CPT, RYT—will help you increase your caloric burn, improve your strength, increase muscle ...

Advanced: 50 or more per day (split across sets) If you're able to do 15 pull-ups in one set, aim for sets of around 10; this keeps you within 3 to 5 reps of failure, which is ideal for building ...