Having a tighter and more toned buttocks is on the “wish list” of many people. A relevant part of the body and potential problem area is your lower back. You might not think much about this area unless you experience back pain. Not all back injuries can be avoided, but some can. Strengthening the muscles around the hips and lower back is an important step toward minimizing any potential backaches or injuries. Of course, any time you exercise your lower back directly, you must maintain a high level of concentration and care, because sloppy exercise form could result in the type of pain you’re trying to avoid.
Wouldn’t it be wonderful if a single exercise could tighten your gluteal and hip muscles and at the same time, firm and strengthen your lower back? Prone thigh extensions (also called reverse back extensions) can activate all the muscles in this area and do it very well. Performing this exercise on a ball makes it a little more fun and comfortable and provides pelvis stability and freedom of movement as you strengthen and firm your gluteal muscles.
Gluteal and Hip Muscles
Prone thigh extensions activate the gluteus maximus. This is the largest and strongest of all the hip muscles and it forms the majority of the shape of the buttocks. The gluteus maximus muscle attaches to the bones of the hip and the sacrum, and along the lumbar area of the lower back. It also attaches to the posterior part of the femur (thigh bone) at a section referred to as the “gluteal line” or “gluteal tuberosity.” When the torso is fixed (as in prone thigh extensions) and the hip joint is free to move, the gluteus maximus muscle forcefully extends the femur bone of the thigh.
Although you might not think that the hamstring muscles have much to do with your behind, they provide part of the shape that accentuates a firm buttock. Furthermore, the hamstring muscles strongly contract during prone thigh extensions by pulling the femur bone of the thigh toward the back. The biceps femoris muscle of the hamstring group has two heads. The long head attaches to the ischial tuberosity of the hipbone structure. The fibers of the short head begin on the lower one-third of the femur bone just above the knee, but because they don’t attach to the ischial tuberosity, the short head isn’t considered a “hamstring” muscle. Both heads of the muscle fuse into a thick tendon, which crosses the lateral side of the knee joint to attach to the fibula bone (and some ligaments) on the knee.
The second muscle of the hamstring group is the semitendinosus. The semitendinosus fibers attach to the ischial tuberosity and insert into a cord-like tendon about two-thirds of the way down the posterior thigh. The semitendinosus crosses the knee joint posteriorly to attach to the medial side of the superior part of the tibia (the large medial bone of the leg). As a result, they become important extensors of the back and assist the erector spinae during prone thigh extensions.
The erector spinae are a group of three postural muscles situated along the spine. They consist of the iliocostalis, longissimus and spinalis muscles. The fibers of the erector spinae arise from the iliac crest (part of the hipbone) and along the sides and middle projections of the vertebrae. They run superiorly (toward the head) and insert into the ribs and vertebrae that are superior to where they begin. The thoracolumbar fascia covers these muscles posteriorly. This is a tough sheet of connective tissue (fascia) that doesn’t have much flexibility. Thus, it’s prone to injuries from extreme stretching or jerking. The erector spinae lie just deep to this fascia covering.
Collectively, the erector spinae group is the strongest extenders of the vertebral column. Acting on one side of the body at a time, each of these muscles can bend the vertebral column laterally (for example, when doing side bends), rotate the vertebral column in a twisting action and of course, extend the spine from a flexed position. The spine is fixed in prone thigh extensions, so the erector spinae fibers that attach to the hipbones and lower lumbar vertebrate help to pull the hips and stabilize the pelvis during the points when the thighs move upward (thigh extension) in prone thigh extensions.
If you’ve had a prior lower back injury, you should choose another exercise that won’t generate as much torque through the lumbar and sacral areas of the hips. However, if your back is weak, but otherwise healthy, start with 10 repetitions and work up to three sets of 15-20 repetitions over a couple of weeks.
1. Lie facedown on a large ball. The ball should be comfortably placed under your pelvis, upper thighs, and lower abdomen. Don’t put the ball too low across the thighs or too high on the abdomen.
2. Place your palms on the ground with your elbows straight. Extend (straighten) your knees but let the toes of your shoes contact the floor. Your feet shouldn’t touch the floor unless you flex your hips. Make sure your hands are stable on the floor, so the ball won’t roll out from under you.
3. Keep both feet together. Lift your legs but keep your knees straight. Continue lifting them upward until your thighs and legs are parallel to the floor. The movement should come from the hips. Make your lift smooth but forceful and take about one second from the bottom to the top.
4. Don’t lift higher than this or you’ll hyperextend your back as this would create unnecessary compression forces through your intervertebral disks, without improving the quality of the muscle activation. The force should come smoothly (no jerking or uncontrolled, fast movements should occur) from your erector spinae, hamstring, and gluteal muscles. Exhale as you lift your legs (thigh extension).
5. Hold the top position for a count of three. Slowly reverse your direction, flex your hips, and control the descent of the weight of your legs until they’re just short of the starting position. Inhale as you lower your legs. It should take 3-4 seconds to lower your legs back to where your toes almost contact the floor. Don’t let them touch the floor as you start upward again. This will maintain tension on the muscles throughout the effort.
6. Work up to 15-20 repetitions before resting. After a break of about a minute, repeat the set for another 15-20.
You’ll probably find that there’s a bit of a “burn” in your gluteal muscles by the time you get to the 10th repetition, while your back and hamstrings may feel tight after your set is over. If your hamstrings become too tight (and if you do a lot of sitting during the day, they’ll already be too tight) this could contribute to lower back pain if left unchecked. The remedy for the tight muscles is to stretch your hamstrings and lower back between sets. Toe touches with straight knees or sitting on the floor and bringing your chest to your thighs will do the trick.
Don’t let your legs drop too quickly from the top position. The muscles will be more fully activated if you have a slow and controlled leg descent. The key to injury-free exercise is always maintaining strict control of your body. It’s also worth emphasizing that you shouldn’t swing your legs upward.
After only a few weeks, you should find that this exercise has revitalized your lower back, and your buttocks will be much firmer. Your back stiffness and the fatigue you get from sitting at a desk for long periods of time will all but vanish. Furthermore, your risk of injury will be significantly reduced.
1. Davis DS, Ashby PE, McCale KL, McQuain JA and Wine JM. The effectiveness of 3 stretching techniques on hamstring flexibility using consistent stretching parameters. J Strength Cond Res, 19: 27-32, 2005.
2. Lehman GJ. Trunk and hip muscle recruitment patterns during the prone leg extension following a lateral ankle sprain: A prospective case study pre and post injury. Chiropr Osteopat, 14: 4-9, 2006.
3. Lehman GJ, Lennon D, Tresidder B, Rayfield B and Poschar M. Muscle recruitment patterns during the prone leg extension. BMC Musculoskelet Disord, 5: 3-9, 2004.
4. Plamondon A, Serresse O, Boyd K, Ladouceur D and Desjardins P. Estimated moments at L5/S1 level and muscular activation of back extensors for six prone back extension exercises in healthy individuals. Scand J Med Sci Sports, 12: 81-89, 2002.
5. Plamondon A, Trimble K, Lariviere C and Desjardins P. Back muscle fatigue during intermittent prone back extension exercise. Scand J Med Sci Sports, 14: 221-230, 2004.
6. Stevens VK, Vleeming A, Bouche KG, Mahieu NN, Vanderstraeten GG and Danneels LA. Electromyographic activity of trunk and hip muscles during stabilization exercises in four-point kneeling in healthy volunteers. Eur Spine J, 2006. published online ahead of press DOI 10.1007/s00586-006-0181-1.