You just need nine minutes and a set of dumbbells to build ab muscle

If you want to develop your abs and core muscles, you might think you need to do endless crunches. However, this short dumbbell routine can strengthen your mid-body muscle in just nine minutes without a sit-up in sight.

It's worth investing in a set of the best adjustable dumbbells if you'll be training at home. These customizable weights combine several dumbbells in one for easy storage, and you can increase the load as you get stronger.

If you're working with fixed-load dumbbells at home or the gym, you can use this guide to find out what dumbbell weight you should use instead. With equipment by your side, you'll be ready to take on personal trainer Rhiannon Bailey's dumbbell abs routine.

At just nine minutes, it's ideal for when you're tight on time or as an abs-focused addition to your regular exercise session. To fit the three core strengthening exercises into the time, you'll train for 40 seconds, take a 20-second rest, then start on the next move.

If this is your first time exercising with dumbbells, you can lower the intensity by switching to a pattern of 30 seconds on/30 seconds off instead. You can practice your technique with Bailey's demonstrations to get the most from the short session.

Watch Rhiannon Bailey's nine-minute ab workout

This exercise style is known as high-intensity resistance training (HIRT), where you work intensely for short bursts with minimal rests between moves. Working out this way helps you pack a muscle-building session into a short time, but there are other benefits too.

Keeping the intensity high also raises your heart rate, helping you burn more energy during your workout than in an equivalent steady-state routine. Sustaining it throughout the session also boosts your metabolism, the amount of energy you burn at rest.

It's a similar technique used in cardio-focused high-intensity interval training (HIIT) sessions, which is why many people take on a HIIT workout for fat loss. Bailey's routine combines the two for a muscle-building, metabolism-boosting workout in less than 10 minutes.

People often use abs and core interchangeably, but if you've been wondering what is the core muscle, there are a few differences between them. Your core is a section of mid-body muscle that connects your upper and lower body.

This includes your rectus abdominis, otherwise known as the six-pack abs muscle. To help build strength in your core and visible ab muscle, it's worth adding one of the best protein powders for weight loss to your post-workout routine.