Hip flexors are important muscles to target when weight training to build functional strength in the legs. Learn how to do hip flexor exercises in this strength training video. Take action: knees to chest exercise targets core, hold weight between feet, raise knees as high as you can, start in push up position and bring alternate knees to elbows, and work for quick reps and endurance. Tom Clifford, the instructor in this how-to video, has a degree in physical education, fitness and health from Eastern Michigan University, where he ran track and cross-country. Tom has worked as a personal trainer for two years. He also has a separate business where he coaches runners and triathletes for upcoming events. He currently works at Gold's Gym in Wilmington, North Carolina. Watch this video body sculpting tutorial and learn how to strengthen the hip flexor.