KEY AREAS: core strength, obliques, spinal mobility
START POSITION: Stand up straight holding one (fairly heavy) dumbbell close to one side. Place the hand of the opposite arm onto the back of your head with elbow bent. Feet should be no more than hip width apart or a little bit narrower.

NOTES: To perform the Dumbell Sidebend correctly, I have 6 key tips:
1) Don’t move your neck position – just allow your head to tilt as your torso dips to one side.
2) Keep the dumbbell close and touching your side all the way down and back up again – not pressed in – just a soft touch is fine.
3) Focus hard on making an effort to tense your core on both sides as you lean over, but particularly tense it firmly as you raise the dumbell up.
4) Don’t bend the knees or use any other part of your body to assist the movement, except your Core and Obliques.
5) Allow the weight of the dumbell to pull your arm straight down from the shoulder, but don’t use any arm muscles to assist the moves. You should stop the downward move as soon as the upper tricep becomes vertical, and when the dumbell is well above your knee.
6) Breathe out when rasinnig the dumbbell, and in when lowering the dumbbell.
Back in the old-school days I remember that this exercise was recommeded to me by a boxing coach (and by the owner of my favourite ever Gym – Bobs Gym in Avonmouth, Bristol, England) to help build strong oblique muscles because my sides were not able to withstand heavy body punches. Bobs was true old-school – rough and ready and raw, with extra focus on technique. The modern gyms sometimes seem far too clean, polished and fluffy for my liking (and expensive!). Anyway, the Dumbbell Sidebend is undoubtedly a timeless classic, and the obliques are often overlooked and forgotten about. Please learn it.
Perform several reps on one side before switching the dumbbell to the other hand and working on the other side. Be carefull when starting out with this exercise, because most people have under-developed Oblique strength. However, the Oblique muscles will normally increase their strength and adapt very quickly to regular training which will allow you to move up to heavier dumbells quite quickly.
So, when starting out, your reps should be much higher, but as you increase the weight you should do less reps and more sets (particularly if your aim is to get super strong as opposed to just toning up and getting into shape).