Strength Exercises for Hip Flexors--The Main Kicking Muscles

by Thomas Kurz

In this article you will learn about strengthening the hip flexors—the main kicking muscles. The strength and endurance of the hip flexors (the iliopsoas muscles) determine both the power and the height of your kicks.

If you have followed the program of conditioning for martial arts, as described in my previous articles, you should be ready for more intensive hip flexor exercises than sit-ups. Sit-ups strengthen both the abdomen and hip flexors (see the article “Beginning Strength Exercises for Abdomen and Lower Back”). In sit-ups on the floor, however, the hip flexors work only through a small part of their full range of motion. To strengthen the hip flexors through a greater range of motion than that, you need to do leg raises.

Leg raises develop the strength and muscular endurance you need to kick with great power; they are also good for the intensive stretching exercises that lead to front and side splits. Introduce leg raises on the floor into your strength training as soon as your abdomen and lower back are strong enough not to bother you during or after the leg raises. As I wrote in the earlier article on the “Sequence of Conditioning Exercises for Martial Artists,” you should be strong enough for lying leg raises without weights when your abdomen does not feel weak during 10–15 repetitions of bench extensions with extra weight equaling 1/3 of your body weight.

Lying leg raise. Lie on your back with legs straight. Inhale and then press the small of your back to the floor. Exhale as you raise your legs until they point straight up and then lower them while still exhaling. In lying leg raises you must keep your lower back pressed to the floor throughout the movement. Do only the number of repetitions that can be done without fatiguing your lower back and without lifting the small of your back off the floor. You should start with very few repetitions and no weights. Gradually increase the number of repetitions up to a 100. When you can do 100 repetitions, start using ankle weights with a minimal load. Increase the load after you reach 100 repetitions with it. Eventually you will arrive at such loads as to make it difficult to do 100 repetitions while maintaining good form. At that point increase the load but reduce the number of repetitions down to thirty (or whatever number you can do while maintaining good form) and do one or two sets.

Lying leg raise

When you can deadlift once or twice a barbell weighing twice as much as you, it should be safe for you to progress to lying leg raises with weights and hanging leg raises. As you strengthen your lower back and lift more in the back extension on the bench, in the good morning, and in the deadlift, you should be able to use gradually heavier weights in lying leg raises. (See articles “Sequence of Conditioning Exercises for Martial Artists,” “Beginning Strength Exercises for Abdomen and Lower Back,” and “Advanced Strength Exercises for Lower Back–Your Best Insurance against Back Pain.”)

Hanging leg raise. Hang on the bar using the overhand grip. Your feet should be hanging clear of the floor. Inhale and then tense your abdomen as if you were doing a reverse crunch. This is to round your lower back so your lumbar lordosis is as little as possible. Raise your legs up to the bar as you exhale and lower them while still exhaling. Try to work up to thirty repetitions.

If, in hanging leg raises, you cannot keep your lower back rounded or at least keep it from exceeding the normal lower back lordosis while raising and lowering your legs, stop! You can get back pain if you continue.

Hanging leg raise

If raising straight legs to the bar is too difficult, try raising bent legs as if to bring your knees to your chest. Do both the lying and hanging leg raises slowly, stopping at the end of each repetition.

When your hip flexors are strong enough to do ten or more hanging leg raises, you can progress to strength exercises that isolate your inner thigh muscles (thigh adductors). These are exercises such as adductor flys and other even more intensive strength exercises for the inner thighs shown on the DVD Secrets of Stretching. (These inner thigh exercises develop both the strength and the flexibility needed for doing side splits without a warm-up and even while suspended between chairs.) Caution: If your lower back and the hip flexors are not strong enough to keep the correct form when doing the adductor flys, you can damage your hip flexors and your lower back.

For answers to questions on strength exercises described in my articles so far, see Questions and Answers on Strength Exercises.

Training Tips of the Article

In lying leg raises you must keep your lower back pressed to the floor throughout the movement. Do only the number of repetitions that can be done without fatiguing your lower back and without lifting the small of your back off the floor.
In hanging leg raises, if you cannot keep your lower back rounded or at least keep it from exceeding the normal lower back lordosis while raising and lowering your legs, stop!

Resources for Further Study
Flexibility Express: Flexibility and Functional Strength in No Time

This easy-to-follow DVD offers a proven method of increasing your range of motion while increasing your strength—whatever your age or flexibility level.
You will learn innovative functional exercise progressions from weighted squats to splits and back bridges. Each exercise will build your muscles while increasing your flexibility, saving both your time and energy. The saved time and energy then can be used for more and better practice of your skills.

Secrets of Stretching: Exercises for the Lower Body

This DVD features an introduction to general conditioning and follows that with four exercise routines—one for beginners, one for intermediate, and two for advanced athletes. Viewers will learn plenty of how-tos. The focus is on flexibility and strength training.