The inner/outer-thigh—a.k.a. adductor/abductor—machine is the result of too many trainees overstretching and spraining knee ligaments by using cables attached to their ankles for inner- and outer-thigh-muscle training. The machine pads by the knees and ankles reduce or eliminate stress on the ligament on the inner side of the knee.
When the inner/outer-thigh machine was introduced, it gained popularity immediately for reasons that weren’t necessarily realistic. I am referring to the concept that you can “spot reduce”—that is, work an area and reduce bodyfat in that bodypart. Many female trainees tried to lose inner-thigh and hip bodyfat by using the inner/outer-thigh machine. The only improvement that took place was development of the inner-thigh and outer-hip muscles and the burning of the calories it took to train those large muscles. Male trainees started using the machine as another leg-training tool.
The benefit of the inner/outer-thigh machine is that muscles that are often neglected, and therefore imbalanced, can be specifically increased in strength and size. That can make the hip feel more secure during other leg exercises.
It is difficult to strengthen those two sets of muscles. The inner/outer-thigh machine is an “open chain,” or nonweight-bearing, exercise. While that’s probably a nonissue for the average trainee, it may not be desirable for athletes who need to have their strength training count the most. Athletes usually benefit more from “closed chain,” or weight-bearing, exercises like the squat. A wider-stance squat, such as a powerlifting-style squat, places more emphasis on the adductor muscles than a narrower-stance squat. Wide-stance squats can strengthen the inner thighs significantly and may be more useful to athletes in other sports.
The inner-thigh muscles are larger and ultimately stronger than the outer-thigh and hip muscles and should be trained accordingly. When you place too much emphasis on the outer-thigh muscles, lower-back pain can result. If you use an adductor/abductor machine, allow enough time and adaptation to let your inner-thigh muscles become stronger than the outer-thigh muscles.
If using the inner/outer-thigh machine causes hip pain, stop doing it. Every exercise isn’t for everyone. If you have underlying hip arthritis, the movements can be very painful, and there are other problems that can keep you from performing them as well. One has received progressively more attention over the past eight to 10 years: an impingement in the hip. Some patients have a little more bone that formed at the base of the ball of the femur, or thighbone, near the hip socket. That little bit of extra bone can impact the socket and prevent a full range of motion. The point of impact in the joint, which is not normal, can chip off cartilage lining the socket and even small pieces of bone. That creates another problem—namely, the chips or loose bodies in the joint. Loose bodies in a weight-bearing joint can lead to rapidly accelerating arthritis from the wear and tear they create.
Another injury is possible in the hip socket, which has a cartilage ring around it called the acetabular labrum. As the thighbone moves out in the inner/outer-thigh exercises, the labrum can be torn from the bony impact, producing painful clicking and popping in the hip. If you experience that or have pain in the hip that refers to the inner thigh, you should have your hip evaluated by a sportsmedicine orthopedic surgeon or sportsmedicine chiropractor. It could save your hip from significant wear and tear.
The inner/outer-thigh machine can be a useful addition to your workout—but don’t ignore hip pain. Training isn’t supposed to cause joint pain. Train smart, then train hard.
—Joseph M. Horrigan
Editor’s note: Visit www.SoftTissueCenter.com for reprints of Horrigan’s past Sportsmedicine columns that have appeared in IRON MAN. You can order the books Strength, Conditioning and Injury Prevention for Hockey by Joseph Horrigan, D.C., and E.J. “Doc” Kreis, D.A., and The 7-Minute Rotator Cuff Solution by Horrigan and Jerry Robinson from Home Gym Warehouse, (800) 447-0008, or at www.Home-Gym.com.