Quick anatomy lesson: You know the obliques, those muscles along the sides of your waist? Well, they do so much more than provide the shape of your waistline. Functionally, they control your body’s ability to bend and twist (and resist bending and twisting — like, say, when you’re carrying a lopsided load, such as a shoulder bag or a suitcase). They also support your spine, internal organs, and even your breathing. Having strong obliques, therefore, can keep your posture upright, reduce the risk of muscle strain when you're lifting and moving heavy things, and even prevent and reverse back pain.
The following exercises train the oblique muscles to do their jobs even better. Aim to do these intentionally and with good form for 30 to 60 seconds of effort (if you find it easier to count, that’ll likely be in the 10-to-15 rep range). Add one or two into your total-body circuit training, or choose three or four to do as a circuit on their own.