Only got one dumbbell? Perfect. Uneven weighted exercises can be a good way for moderately experienced exercisers to get more core activation while doing traditional weights exercises.
For example, the chest press on a ball or bench using only one dumbbell or one heavy and one light dumbbell. Your body has to work harder to balance the uneven weight distribution so it’s a bonus for your trunk muscles, gluteals and hamstrings.
You could try the following exercises using only one dumbbell:
Chest press. Head on ball, feet on floor, aim to keep hips raised and level while you press with one arm. The other hand could be placed on the hip.
Walk lunges. Keep looking forward and keep hips level.
Lateral raise. Feet close together or stand on 1 leg to minimise stability.
Biceps curl. One arm bent over row. Forward raise.
Any exercise with dumbbells can be performed with uneven load, placing the emphasis on maintaining correct body alignment during the move. Use caution to begin with, and use a lighter load than normal until you get the hang of it.
Uneven loads replicate what is happening in our lives, so it is useful to train in this way too.