As a personal trainer, this is the one mobility exercise I recommend starting with to build a strong, mobile lower body

(Image credit: Shutterstock) Bulgarian split squats have been having a real moment in the world of fitness, partly because they are torturous and partly because they are incredibly effective at building your legs and glutes when done properly.There's a lot of debate around how to do Bulgarian split squats with proper form to maximize the return on your glutes or quads, but there's a BSS with a twist (quite literally) that can build strength and increase mobility, too.Never one to turn down an exercise with double, or even triple, benefits, I strongly recommend trying this move the next time you want to work your lower body hard. Here's how to do it, plus the benefits.How to do itI'd classify this BSS variation as low impact, but if you experience pain at any time, stop and rest. If you're working with an injury or health condition, I recommend seeking advice from your physician or a trainer before starting this exercise, especially if you suffer from knee pain.For many, the knees are an all-too-familiar problem area, but that doesn't mean you can't build strong legs and glutes; it just means choosing the exercises that remain low impact while offering high return in building strength and muscle. What works for one person won't always work for another, so it's about trial and error in the beginning.Stand with your back leg on a chair, box, or bench, top of the foot pressed down.Square your hips so that you balance on your front leg, with a soft bend in both knees.Hold a weight in both hands or bring your hands to your hips and engage your core.Bend your knees to lower toward the ground. As you do, arc your back knee toward the bench behind you rather than moving vertically. Vertical will better load the quads. whereas the arc will emphasize the glutes.Hinge forward slightly as you lower, keeping your spine long. This will also help activate your gluteal muscles and load the front leg.Pause, then drive upward to stand.Rotate to the side away from your front leg, pressing your foot down into the box and drawing your knee outward while leaning into the stretch to open your hips and adductors.Complete 6-8 heavy reps, then switch sides.If you'd like, add a twist over the front leg at the bottom of the split squat.Why?Bulgarian split squats famously build your hips, glutes and legs, strengthen your core, improve balance, stability and coordination and test unilateral ability by emphasizing one side of the body at a time.It's a tough move you can load heavily while focusing on single-leg balance and control. The added benefit of the twist at the bottom of the split squat is that torso rotation works the internal and external obliques, which are extremely important core muscles.Get instant access to breaking news, the hottest reviews, great deals and helpful tips.The twist at the top of the exercise offers even more benefit for your hips and inner thighs, as you rotate and draw the top knee over the ankle, leaning away from the front leg. It's a great way to open the lower body through dynamic stretching while gently increasing joint mobility.Follow Tom's Guide fitness on Instagram for more workouts, routines, tips, and tricks. Follow Tom's Guide on Google News and add us as a preferred source to get our up-to-date news, analysis, and reviews in your feeds. Alternatively, you can read our content on the Tom's Guide app available now for iOS and Android. Subscribe to Tom's Guide on YouTube and follow us on TikTok. More from Tom's GuideI teach people how to be more mobile: 3 low-impact back and shoulder moves that build stability and strength after 40According to a personal trainer, this exercise is 100 times more effective than crunches. I tried it and was humbledI teach people over 50 to be mobile: 3 low-impact moves that build more stability than a 30-minute walk Sam Hopes is a level 3 qualified trainer, a level 2 Reiki practitioner and fitness editor at Tom's Guide. She is also currently undertaking her Yoga For Athletes training course. Sam has written for various fitness brands and websites over the years and has experience across brands at Future, such as Live Science, Fit&Well, Coach, and T3. Having coached at fitness studios like F45 and Virgin Active and taken on both 1:1 and group, Sam now primarily teaches outdoor bootcamps, bodyweight, and kettlebells. She also coaches mobility and flexibility classes several times a week. Sam has completed two mixed doubles Hyrox competitions in London and the Netherlands and finished her first doubles attempt in 1:11.