20 minutes and two dumbbells are all you need to build strength all over

One of the most common reasons people struggle to keep up with an exercise routine is that it's difficult to find the time, but you don't need to spend hours in the gym. Adopt the motto 'something is better than nothing' and you may be surprised by how quickly you feel different—stronger and more full of energy.

Fitness trainers Nicole Winter and Maggie Sullivan recently shared a workout on Instagram that gets a lot done in a short space of time.

In just 20 minutes this routine targets a wide range of muscles across the entire body including the legs, glutes, shoulders and core. Plus, all you need is a pair of dumbbells.

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How to do Nicole Winter and Maggie Sullivan's dumbbell workout

There are four exercise combinations in this routine, and Winter and Sullivan recommend doing each move for 40 seconds followed by 20 seconds of rest. Complete the sequence five times in total for a 20-minute workout.

This is a dumbbell-only workout, but it might be worth having a couple of different weight options to hand because some of the exercises, such as the triceps kickback and Y raise, isolate smaller muscles and will require a lighter weight than a squat and lunge, which uses larger muscles in your legs.

If the weight you've chosen is so heavy that you need to rest in the 40-second working period, switch to lighter dumbbells. Beginners may even want to perform some moves—like the squat to reverse lunge—just using their bodyweight.

The benefits of high-intensity resistance training

This is an example of high-intensity resistance training (HIRT), which uses the work/rest intervals of HIIT, but replaces cardio exercises with weight lifting. Research suggests working out in this way can keep your metabolism in an elevated state for longer than traditional weight lifting, but you'll still build muscle and strength.

With short rest periods, there's every chance you'll raise your heart rate and improve your cardio fitness, too. When we quizzed certified trainer Tom Cuff-Burnett about the benefits of HIRT , he said, "if you have limited time and bandwidth for your training, and have access to some level of gym equipment, the smart money would be to adopt the HIRT method for the best all-around regime."