(Image credit: Shutterstock) My core strength has improved a lot this year, thanks to a mix of weightlifting, Pilates and yoga. Keeping consistent with a variety of core-strengthening exercises has been crucial for improving stability and balance over time, but there are some moves that work better than others. I've always struggled to feel the dead bug properly, even when trying weighted dead bugs instead. For some reason, even after speaking with a variety of instructors about my form and engagement, one of the best exercises for deep core strength just doesn't do it for me. Article continues below How to do knee tucks I know that slowing exercises to focus on time under tension (how long muscles hold tension during a muscular contraction) has been pivotal in improving core strength, control and stability. It's also had a positive impact on my posture by targeting the deeper muscles that support the pelvis and spine, like the erector spinae and transverse abdominis.…