Breaking news: Some of the most robust individuals around don’t appear to have ever done a crunch in their lives. A powerful core is evident in how you move, maintain posture, and remain injury-free when life presents challenges—like a sudden change in direction, a stumble on uneven terrain, or lifting a heavy suitcase overhead.

As you grow older, core strength becomes increasingly essential in your day-to-day wellbeing. It supports your lower back, stabilizes your spine, and offers a firm foundation for lifting, carrying, pushing, and pulling with more assurance. If your core is weak, other aspects begin to degrade: your balance, posture, power generation, and freedom of movement.

Here’s some coaching insight for you: developing core strength doesn’t involve grinding through sit-ups. The most effective core assessments and exercises challenge your stability and coordination, not just your abs. If you can master one specific movement, your core is likely more advanced, even compared to those younger than you.

That movement is the star side plank. It’s simple on paper, humbling in practice, and an honest test of your strength. If you can hold this, your core is flat-out strong. Here’s why that matters and what you can do if you’re not there yet.

5 Simple Strength Moves That Make You Feel Decades Younger After 40

What Really Defines a Strong Core in Your 30s?

In your 30s, you’ve likely built a good base, but true core strength comes down to what that base can handle. Can it keep your spine stable when things get unpredictable? Can it support your posture through long hours of work and still deliver power in your workouts?

Here’s what a strong core really means at this stage of life:

• You can resist movement as well as create it (anti-rotation and bracing are key).
• Your core connects your upper and lower body efficiently during dynamic movements.
• You can maintain stability in asymmetrical positions or while under load.
• You have control over your hips and ribcage. There’s no excessive arching or rounding in movement and exercise.
• You recover quickly from high-intensity or awkward movements because your core is doing its job.

The Move: Star Side Plank

The star side plank is a full-body stability challenge that demands control from your entire core, as well as your glutes, shoulders, and legs.

This move puts you in an unstable position, forcing your core to work overtime to prevent rotation or sagging. It also engages your hips and shoulder stabilizers, testing strength across your entire chain.

Muscles Trained: Obliques, Transverse abdominis, Glute medius, Quadratus lumborum (QL), Shoulder stabilizers (especially the rotator cuff and delts), Adductors and abductors.

How to Do It:

1. Lie on your side with your elbow directly under your shoulder and feet stacked.
2. Press through your bottom elbow and foot to lift your hips off the ground into a side plank.
3. Raise your top arm and top leg toward the ceiling to form a star shape.
4. Keep your body in a straight line from head to heel.
5. Hold the position for 20–30 seconds per side, or longer if you can maintain proper form.

Form Tip: Drive your bottom elbow into the ground and keep your ribs pulled down. Don’t let your hips rotate forward or back, aiming to stay square and stable.

Best Regressions:

• Standard side plank with knees bent
• Side plank with feet staggered
• Side plank with top leg resting on a low box
• Side plank with pulses before progressing to holds

If You Can Master These 5 Movements After 45, You’re Aging in Reverse

Not Satisfied With Your Core Strength? Here’s How to Improve It

The star side plank may feel out of reach. That’s fine, every strong movement has a path leading up to it. The key is to train smart, stay consistent, and gradually increase the challenge to your core without losing form.

Here’s how to level up your core strength and work your way toward mastery:

• Train anti-rotation with moves like Pallof presses and single-arm carries.
• Strengthen your lateral (side) core with side planks, Copenhagen planks, and suitcase carries.
• Build full-body tension through planks, dead bugs, and bird dogs.
• Work in tempo: slow reps with control to teach your core to stabilize better.
• Focus on breathing: exhale fully to engage your deep core muscles.
• Utilize movement-based drills, such as mountain climbers and bear crawls, to train stability in motion.

Remember, your core isn’t just something you hit on “ab day.” It’s the foundation of everything you do, and when it’s strong, everything else becomes easier. Whether or not you’re holding the star side plank just yet, the path to getting there will make you stronger where it counts.

Jarrod Nobbe, MA, CSCS