The dumbbell step-up is a compound strength-training exercise that develops the major muscles in the lower body. In addition to a pair of dumbbells, it also requires the use of a plyo box or bench. While holding the dumbbells down by your side, place one foot completely on the box and then drive off that foot, pulling up your trailing leg to land alongside your lead foot and place you in a standing position atop the box. Adjust the weight of the dumbbells you use to increase or decrease the challenge placed on your lower body muscles.
The primary muscle involved in the dumbbell step-up is the quadriceps. The quadriceps is actually a collection of four muscles, including the rectus femoris, vastus lateralis, vastus intermedius and vastus medialis, that are located at the front of your thigh. Together, they’re responsible for knee extension, or straightening your knee, which is the joint movement that occurs as you step up onto the box. The higher the step, the greater degree of knee extension required and the greater demand on your quadriceps.
Also assisting in the dumbbell step-up are the gluteus maximus, adductor magnus, soleus and gastocnemius. The gluteus maximus, which is the largest muscle in the buttocks, extends your hips, driving your leg backward as you step up onto the box. The adductor magnus is located at the inside of your thighs and contracts to perform hip adduction, which means it brings your legs in toward each other as you complete the step-up movement. The soleus and gastrocnemius are two muscles in your calves and are responsible for performing ankle plantar flexion, or straightening your ankle joints.
Stabilizing muscles don’t produce any movement during the step-up exercise, but they contract to keep you on balance and help you maintain proper posture. According to ExRx.net, the erector spinae muscle, which runs along your spine, contracts to prevent your back from collapsing forward. The obliques, at each side of your torso, also assist in keeping your torso upright, preventing it from tilting to one side or the other. The rhomboids and trapezius muscles near your scapula and shoulders contract to control and limit movement of the dumbbells in your hands.
Simultaneously develop your shoulders and triceps by incorporating dumbbell shoulder press into your step-up exercise. Start with the dumbbells held at your shoulders with palms facing forward. When you drive up off your lead foot to step, simultaneously push the weights up over your head, extending your arms fully. As you lower your foot back to the floor, lower the weights back to your shoulders.
Kim Nunley has been screenwriting and working as an online health and fitness writer since 2005. She’s had multiple short screenplays produced and her feature scripts have placed at the Austin Film Festival. Prior to writing full-time, she worked as a strength coach, athletic coach and college instructor. She holds a master's degree in kinesiology from California State University, Fullerton.