Spot reduction is the Holy Grail of sports medicine. Unfortunately, the most determined researchers haven't been able to show that it's possible to target a body part for fat or weight loss. So all of the leg lifts and crunches in the world won't give you six-pack abs. Leg lifts do, however, work the hip flexors, which help to support your core and lower your risk of injury. The trick is to do them correctly and increase your reps gradually.
The Physical Activity Guidelines for Americans recommends eating a healthy diet and following an exercise regimen that includes cardiovascular and strength training.
The Science Behind It
It's a common belief that leg lifts strengthen the lower abdominal muscle. It might very well feel that way, as the exercise does produce fatigue in the pelvis area, sometimes felt as a burning sensation, that can be mistaken for the lower portion of the lower abdomen.
However, the fact is that you are actually working the iliopsoas and rectus femoris says ExRx.net. These are the two hip-flexing muscles that lie deep beneath the sheath of muscle known as the rectus abdominis which is the fancy name for your lower abs.
The hip flexors play an important if complex role in core support, especially of the lumbar spine. Leg lift benefits include helping to stabilize your lower back, improving your posture and alignment that also improve your appearance. More important, it makes you more resistant to injury and lower back pain reports a 2016 study in the Journal of Physical Therapy Science.
Start abdominal leg raise exercises from the "up" position. After lowering the leg almost to the floor, let it spring back up before it touches the floor. This puts strain on the back, so stop if you feel pain and lift the legs back up. Over time your lower abdominal muscles will be strong enough to take you through the full range of movement.
Tips for Avoiding Injury
- Tight hamstrings could keep you from fully straightening your legs — only straighten as far as you can without pain.
- Keeping the lower back flat protects it from injury.
- The leg and foot should be fully engaged. Stretch the knee and work that muscle so you're building strength throughout the apparatus. That will also work the abs harder and improve coordination.
- You can place your hands under your butt but not your lower back.
- How many reps? That, of course, depends on your condition. Start with one set of 10 and work your way up to three sets of 10.
1. Single-Leg Lift
HOW TO DO IT: Lie flat on your back, knees bent vertically to 90 degrees. Press your shoulders down your back. Press your forearms flat against the ground, palms down, near the hips. Press your lower back into the floor.
Pressing your lower belly and lower back into the floor, curl your rising knee up and over your belly, toward the chest. With the knee as hovering over a flat, stable lower back, extend the lower leg upward and straighten it as much as possible.
Lower the leg at a smooth and even pace. Your leg only has to drop a few inches below the vertical line above your hips to work the muscles.
Lower the leg, push it out and away from the body using the butt and back as it rises to protect the lower spine from strain. Try for 10 reps on each leg. Rotate the leg open from the hip on the second set.
2. Double-Leg Lift
These are performed exactly as single-leg lifts with two exceptions: Press your feet and knees completely together, forming one stable unit, as both feet leave the ground. Point your feet as you take your legs down and up once your legs are vertical .
Double-leg lefts should be approached with particular care. Because they engage the hip flexors, which originate in the lumbar spine, there is a risk of hyper-extending the lower back warns the University of New Mexico. Single-leg lifts with the opposite foot on the floor may be better for some.
- University of New Mexico: "Contraindicated and High-Risk Exercises"
- Journal of Physical Therapy Science: "Comparison of Muscular Activities in the Abdomen and Lower Limbs While Performing Sit-Up and Leg-Raise"
- ExRx.net: "Lower Abdominal Myth"
- U.S. Department of Health and Human Services: “Physical Activity Guidelines for Americans”