In this article, we will take a look at two of the most popular and effective abdominal exercises: Planks and crunches. Both are among the top contenders in the battle to replace the sit-up. Although sit-ups are a time-honored and effective way to increase your core ab strength, they are falling out of favor among most experts. Even the U.S. military has been experimenting with a revised fitness program that doesn’t include sit-ups.
Why Sit-Ups Are Becoming Less Popular
Sit-ups are being rejected by many fitness experts for one primary reason: although these exercises do the job for which they are intended, they also put a lot of stress on the lower back. This high level of stress produces a higher risk of injury to the lower back.
The following is a comprehensive study that measured the relative stress (compression) caused by various abdominal exercises. As you can see by looking at the figures, fixed-leg sit-ups produced the highest compression level.
We can also see that both types of sit-ups produce rates of compression that are dangerously close to the limitsset by the National Institute Of Occupational Safety Hazards. This is a government body that regulates workplace safety in a variety of ways, and they say that anything above 3300 N is considered dangerous. There is a graph near the end of the study cited above, showing that sit-ups can produce compression as high as 3,000 N.
What Is A Plank?
A plank is perhaps one of the simplest exercises you could possibly imagine. It works like this: Put yourself into a push-up position, with your feet on the floor and plant both hands on the floor, about shoulder-width apart. Now, all you have to do is hold that position for as long as possible.
This exercise is much easier on the lower back because it allows your abdominal muscles to fulfill their primary function rather than working against such. You see, the main purpose of the abs is to brace the spine and help it to support the weight of the entire body. This exercise forces your abs to do the work of keeping your back straight. That being said, some of the body’s other muscles are also coming into play.
There is a significant amount of research to show that you should not focus entirely on one muscle group. The study cited above shows that you can achieve a higher level of muscle activation in the trunk by incorporating the distal (most distant) muscles. Integrated exercises that include these muscles have been shown to be more effective and to reduce the risk of an injury. In this regard, planks are a highly optimal choice.
What Is A Crunch?
A crunch is basically a shortened sit-up. Although the crunch and the sit-up use similar methods, the crunch puts a lot less stress on the lower back and focuses most of the burn upon those crucial upper abs.
Of course, proper technique is of the utmost importance. The main thing is to avoid grabbing your head and pulling on your neck. This will put more stress on your neck and upper back, thus defeating the safety factor. Instead, lightly touch your fingertips to the side of your head or neck. This way, you don’t even have the option to pull on your neck (which is cheating, anyway!).
A Word About The Importance Of Tension:
For both of these exercises, it is essential to flex your abs and maintain tension. If you do not do this, you will not obtain the full benefits of the exercise, thus making the whole thing into a waste of time.
When doing a plank, it is important to maintain the tension of the abdominal muscles. Don’t just passively hold the position. Instead, flex those ab muscles and hold the tension with every breath.
When doing a crunch, you pretty much have to flex the abs when you come upward. However, the downward half of the sit-up is actually more important. If you do not maintain tension on the abs as you return to the floor, you are losing at least half the effectiveness of the exercise.
Let The Battle Begin
Since these exercises are both known to be effective, we will need to look at their benefits and shortcomings in greater detail to determine which is superior. We will do this using a simple point system.
Range Of Muscles Targeted
As you can see and feel, crunches will mainly target the Rectus Abdominus muscles. Indeed, the focus on the muscles of the “six-pack” is the main reason for the popularity of this exercise. Crunches also give you a decent burn on the obliques (side muscles).
The plank, by comparison, targets a wider range of muscles. Not only does it work the abs and obliques, but it also gives you a good workout on the shoulders, chest, glutes, and calves.
According to most sources, planks seem to burn more calories. Crunches have been studied in recent years and found to be woefully inefficient in terms of how many calories are burned. This is a big deal for those who are primarily interested in weight loss, as there is no sense in making things harder than they already are.
In terms of muscle-building, the research that we have already examined seems to indicate that both are about equal. However, because the plank targets a much wider range of muscles, the stress is spread out. This could be bad for those who want to specifically target the “six-pack” muscles of the Rectus Abdominus. Thus, there is no winner here. It all depends on your needs and preferences.
Risk Of Injury
The comprehensive study that we examined earlier can answer this question. There is no doubt that sit-ups (referred to as curl-ups in this study) have a higher risk of injury than planking. In fact, they are only a little better than the standard sit-up in this category.
Before we declare a winner, we should mention that you can choose to use both of these exercises. There is some evidence to suggest that core stabilization exercises (like planking) can actually improve your sit-up performance.
The clear winner of this battle is the plank. It is an easier exercise, and yet it targets a wider range of muscles and produces the same results with a lowered risk of injury. Only those who want to specifically target the “six-pack” muscles even need to do crunches at all.
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