
You don’t need the gym to build stronger arms, shoulders, back and chest muscles — this 15-minute workout strengthens the upper body just by using the best kettlebells and five exercises.
The workout should be performed using a submaximal effort, meaning you won’t max out across the 15-minute time cap. But that doesn’t mean you shouldn’t aim for high intensity — try to work at around a seven or eight out of 10 at all times and ramp it up during the last few minutes.