The classic wheelbarrow (one person stands on the hands, while a partner holds the legs) exercise strengthens the body, arms and breast muscles, but try to turn around, so that the back is turned towards the ground, and the fingers points toward your partner. This will strengthen the backside of the arms (triceps). The exercise can be turned into a race, or just be used as a strength exercise, where the wheelbarrow must bend and straiten the arms without moving in any other direction.
Can also be made as an individual exercise. Stand as a crab, with the hands under you, pointing towards the feet, and the hip held high. Arms then bends and the legs lifted one at a time.