 There's nothing better than a per-bum. So here's another exercise to give it a good workout. These are the back-to-back squats Holding the opti-gymbal against your back. Get your partner to stand behind you and press their back against it too Gently leaning against the ball for support. Bend your knees to sit into a squat. Think of the results and no cheating This one kills me, but the end result is so worth it The gymbal is great for working out your chest and triceps too. With staggered feet Hold it and face your partner while they place their palms on both sides of the ball Bend your elbows and bring your chests in towards the ball Next extend both arms to press your upper body away from the ball and that's a rep Keep things simple and fun. This is one of those that actually looks way easier than what it is Your arms burning yet? Yeah, killing