You don't need weights to build leg strength, just this three-move routine

When we have strong legs, we improve our ability to perform everyday activities such as walking, running and climbing stairs. Plus, our coordination increases, reducing the risk of fall-related injuries as we get older.

It's often recommended that we need to train our legs with weights because they contain such large muscle groups. But in this online workout, Sandy Sklar, certified trainer and founder of the XFIT app, uses unilateral exercise and time under tension to really challenge the lower body without weights. Increasing the time the muscle is under tension for really taxes the muscles, and because they are forced to work harder, it can optimize muscular strength, endurance and growth.

"This killer sequence requires no weight," Sklar told her 1.4m Instagram followers, "but feel free to grab a set of dumbbells if you need a little more."

How to do Sandy Sklar's leg workout

The moves:

1. Bulgarian split squat with three-count hold x 10
2. Bulgarian split squat x 15
3. Bulgarian split squat pulse x 20

Sklar says to perform all three exercises on one side, with minimal to no rest. Repeat on the other side. Aim for 3-4 sets.

"Focus on loading the front leg," Sklar says. "Drive up through the heel and keep tension in the glutes."

Why time under tension works

Time under tension is a strength training term that refers to how long a muscle or muscle group is contracting during a move. This type of workout is designed to create tension in the muscle (or muscles) for a longer period, leading to muscle growth.

Adding this technique to your workouts can make your workouts more challenging, and also help you smash through any plateaus. The harder you make muscles work, the better results you’ll see. Stronger muscles in turn improve bone density and, because you burn more calories the more muscle you have, it can help lower body fat.