Tuesday, February 16, 2010

EXERCISE SCIENCE : AB MACHINES: ANY ADVANTAGES? BY JERRY BRAINUM

If you watch television, particularly late at night when infomercials reign, you’ve probably seen one of those commercials touting some kind of abdominal exercise device. Such ads make all sorts of claims, most of which appeal to the vanity of having a smaller waistline coupled with some semblance of abdominal definition. These devices also imply that using them regularly will lead to localized reductions in the abdominal area, also known as “spot reduction.”

Let’s get one thing out of the way from the onset. If you don’t know already, as having found out empirically, actual spot reduction doesn’t exist. When your body burns fat, it does so systemically, not just in one area. Many studies have proven this assertion, even showing that it’s possible to develop an impressive set of abs that are still obscured by a layer of fat; the abs are there, you just can barely see them.

One study involved subjects who did up to 6,000 sit-ups a day, with the result that the abdominal muscles got toned, but with no apparent abdominal definition--unless the subjects also dieted and did aerobic exercise. Another estimated that it takes 4,500 crunch sit-ups to lose one pound of fat over the abdominals.

In fact, it’s possible to produce an impressive set of abdominals from judicious aerobics and a proper diet alone. What happens here is that you simply reduce the fat overlying the abs, and the abs come into bold prominence. So why not forego abdominal training?

Besides making you look fit, having strong abdominal muscles provide a support effect for the torso and especially the lower back area. Most lower back pain stems from a combination of weak abdominal muscles and out-of-shape lumber muscles. When the abs are weak, the lower back tends to increase lordotic tone, or the curvature of the lower back inward. This, in turn, places excessive stress on the spinal vertebrae, leading to a chronic painful lower back. You also want to maintain abdominal/lower back muscle balance to protect you from the stress imposed to this area during exercises such as bent-over rows and squats.

So, even if you expressed no interest in acquiring the highly defined “cube” effect seen with well-toned abdominals, you’d still want the protective effect of having strong abdominals for lower back protection. The question is: what’s the best way to do this, freehand exercise or with any of the new abdominal machines?

Another consideration in optimal abdominal exercise is how much of the abdominal musculature is exercised. Most bodybuilders avoid directly working the oblique muscles that frame the side of the rectus abdominal muscles. In men, fat tends to proliferate on the oblique muscles, euphemistically referred to as “love handles.” However, it’s also true that excessive development of the obliques does tend to lead to a thicker-appearing waist. To prevent such an effect, it’s best to avoid overloading the obliques with heavy exercises such as side bends. Besides leading to thick obliques, side bends also impose a sheer stress on the lower back that could be dangerous.

Another option for oblique training is a twisting motion. In the past, this was often done with an unweighted bar or simply a broomstick, either in a seated or standing bent-over position. This exercise, however, is frowned on by many orthopedic specialists, who point out that similarly to side bends, twisting motions apply sheer stress to the spine, especially during extended range of exercise motions.

More recently, twisting machines have appeared in commercial gyms. Such machines simulate the old bar/broomstick twisting motions in a seated position. These machines do offer more exercise control compared to the freestyle versions, and also allow more weight to be used through supplying an accompanying weight stack. The danger here is twofold: you can still place too much stress on the spine with excessive twisting, and using too much weight could lead to hypertrophy of the obliques, leading to increased waist circumference. Twisting machines, however, do apply a useful effect in strengthening muscles involved in lateral motion. This could prove valuable for specific sports, and in those cases, using these machines makes sense.


As to those newer home abdominal exercise machines, the American Council of Exercise commissioned a study two years ago that compared a few of these exercise machines to freeweight ab exercises, such as crunch or partial sit-ups and reverse crunches. The study, which examined 4 types of commercial abdominal equipment, found no advantage of the machines over simple crunch sit-ups. Two recently published studies looked at various other ab machines, most of which were similar in design to those advertised during those late night sales pitches.

In the first study, Australian researchers compared a device called the “Abshaper” to conventional ab exercises. They attached electrodes to the exercising subjects, with the electrodes feeding electrical activity of the working muscles into a machine measuring such electrical activity (electromyograph). The Abshaper device itself involves lying on your back into a frame that provides arm and head rest support. The exercise motion duplicates that of a conventional partial or crunch sit-up.

Crunch sit-ups have superseded the old-style full sit-ups, which involved raising the entire torso to a sitting position. Such full sit-ups provide too much work for hip flexor muscles, which are deep-lying muscles that exert a pulling effect on the spine. As such, full sit-ups can aggravate lower back problems. Besides, only the first third of the sit-up movement represented by crunch sit-ups work the abdominals; after that, the abs remain isometrically contracted, while the hip flexors take over to pull the body into an upright or sitting posture. The late, great bodybuilding trainer, Vince Gironda, was among the first to recognize this aspect of abdominal training nearly 50 years ago.

The Australian study compared the effects of the Abshaper device on various segments of the abs, i.e., upper, lower, and sides. The Abshaper showed superiority to conventional crunches in the upper segment of the abs, but no difference in muscle stimulation of the lower or side portions of the abs. Conventional ab exercises, however, did bring into play more of the oblique muscles, an effect attributed to the greater need for trunk stabilization between the Abshaper and freehand ab exercises. The abshaper also involved less activity of the front neck muscles in comparison to regular crunches, thought to be due to the head support provided by the Abshaper.


The study also noted that “side crunches” often used to train the obliques, were dangerous to the spine due to excessive load. This confirmed findings from earlier studies about this exercise. In short, don’t do it, unless you want to probably cause lower back irritation.

The other new study examined the effects of four types of abdominal exercise machines. This study involved 19 young, healthy subjects who did either freehand abdominal exercises (crunch with arms up or down; oblique crunch or side sit-ups; and reverse crunches for the lower abs), or the same exercises using 4 different ab machines. The ab machines all featured a similar design to that used in the previously described Australian study, with one exception. One of the 4 machines in the study had a roller-bar that allowed exercisers to stabilize themselves; an effect similar to hooking the feet under a support while doing sit-ups. This is in contrast to most crunch sit-up movements, in which the feet aren’t stabilized to offset excessive hip flexor involvement.

This study also used an EMG machine to measure electrical activity in the exercised ab muscles. Based on these measurements, the study concluded that none of the machines offered any advantage over conventional crunch-type sit-ups. Another finding, similar to that of the Australian study, was the head-supported features of these ab machines produced less neck muscle activity compared to freehand ab exercises. The study authors also noted that if the devices provided the impetus for people to exercise, it would provide a benefit. However, they also cautioned that such devices shouldn’t be expected to produce any significant fat loss in the abdominals without added dietary restraint and aerobic exercise.

One other interesting point mentioned in these studies was that the oblique muscles participate to a far greater degree than previously believed in most ab exercises. This would appear to confirm that added oblique exercises, such as twist machines, may be superfluous, unless used for a specific purpose such as the increased athletic lateral movement training discussed earlier. In short, if you are afflicted with out-of-control love handles, i.e., fat, diet and aerobics are still the best cure.


©,2013 Jerry Brainum. Any reprinting in any type of media, including electronic and foreign is expressly prohibited.


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