Lumbar refers to the lower part of your back, specifically the five vertebrae (the individual bones that stack up to form your spine) between your ribs and your hips. When a doctor talks about your lumbar region or lumbar spine, they mean that curved section of your back that takes so much strain when you bend, lift, or sit for long periods.

You've probably heard adults complain about lower back pain. That's lumbar pain, and it's incredibly common because those five lumbar vertebrae support most of your upper body's weight. When someone lifts a heavy box incorrectly, bending from the waist instead of squatting with their legs, they risk injuring their lumbar spine.

Office chairs often advertise lumbar support, meaning they're designed with extra cushioning or a curve that matches the natural shape of your lower back. Without good lumbar support, sitting for hours can make your back ache. Physical therapists teach exercises to strengthen lumbar muscles, which helps protect those hardworking vertebrae and keep your back healthy and strong as you grow.