Side planks primarily work the oblique muscles, which run along the sides of your core. These muscles help you rotate and bend your trunk and play a crucial role in stabilizing your spine and pelvis

. Unlike traditional ab exercises like crunches that target the front abdominal muscles (rectus abdominis), side planks focus on strengthening the two layers of obliques (internal and external), which are essential for core stability and spinal protection

. In addition to the obliques, side planks engage several other muscle groups simultaneously:

• Deep core muscles such as the quadratus lumborum and transverse abdominis, which support the lumbar spine and help control pelvic movement

• Glute muscles , which contribute to hip and spine stability, reducing strain on other muscles like hip flexors and lower back muscles

• Hip muscles , including hip flexors and abductors, improving movement mechanics and reducing joint strain

• Shoulder muscles , particularly the rotator cuff and scapular stabilizers, which help maintain shoulder stability during the exercise

• The serratus anterior muscle, which supports trunk and shoulder blade stability

Benefits of side planks include:

• Strengthening the core without putting pressure on the lower back, making it a safer alternative to some ab exercises

• Protecting the spine and reducing the risk of back injuries by strengthening spinal stabilizers

• Improving balance and coordination since it is a balancing exercise that requires muscle coordination

• Enhancing posture and potentially reducing chronic lower back pain

• Supporting athletic performance and injury prevention, including reducing hamstring injuries in runners by improving core and pelvic stability

Overall, side planks are an effective, multi-muscle exercise that targets the side core muscles and contributes to overall core strength, spinal health, balance, and injury prevention

. Summary: Side planks work mainly the obliques, deep core stabilizers, glutes, hips, and shoulders, providing core strengthening, spinal protection, improved balance, and injury prevention benefits.