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Just Say No To Sit-Ups And Crunches

Posted Dec 28 2010 7:57pm
While out to dinner with family and friends Christmas Eve, the conversation turned to exercise. Specifically, abdominal exercises.

I attempted to share my opinion on why sit-ups and crunches are not optimal abdominal exercises but the consensus was that I didn't know what I was talking about. As I was told (and yes, this is a quote from the dinner table), "listen to me, I've been doing them (read: sit-ups and crunches) for years."

If nothing else, the conversation has made me very enthusiastic about digging in to all the ugly details on sit-ups and crunches and sharing them here on CFB!

I'll preface this by stating that there is no shortage of research suggesting that sit-ups and crunches are effective in building abdominal strength (although there is a study that contradicts this theory!). Then again, my argument is not narrowly focused on simply whether or not they are effective but rather, are they

1) Safe and,
2) The most effective exercises of choice?

The Ouch Factor

Rarely do you see a person complete just 1 sit-up. The goal is to typically shoot for the moon to see just how many sit-ups you can complete at one time (100, 250, 500?). And there lies the problem as repetitive motions have been shown to be the major factor in disc herniations, with full lumbar flexion (rounding of the lower back) being the major player.

According to Stuart McGill, a professor of spine biomechanics at the University of Waterloo (Ontario, Canada), and one of the foremost experts on the lumbar spine in the world, it doesn't matter whether you are performing full sit-ups or crunch versions. "What happens when you perform a sit-up?" he asks. "The spine is flexed into the position at which it damages sooner."

According to his research, a crunch or traditional sit-up generates at least 3,350 newtons (the equivalent of 748 lbs) of compressive force on the spine. The U.S. National Institute for Occupational Safety and Health states that anything above 3,300 newtons is unsafe.

Another kicker? This type of overload on the abs may not even be effective (read on for the details!).

Risk - Reward

There are some who may argue the "No Pain, No Gain" mantra. My interpretation of this aphorism is that in order to grow we must leave our comfort zone. it doesn't mean that in order to realize gains you need to risk injury!

Trust me, if your goal is to strengthen your core there are plenty of exercises other than sit-ups and crunches that will effectively accomplish this without risking a herniated disk.

Now, here's that kicker I promised you.

Research out of Youngstown State University in Ohio was published in the October 2009 edition of the Journal of Strength and Conditioning Research. That study tested the effects of sit-ups on 71 men and women who were split up in to 3 groups. The control group did no sit-ups. The other 2 groups performed three sets of 20 repetitions (30 seconds rest between sets) of three distinct ab exercises for 11 weeks.

Group 1 performed the sit-ups 3x/week on non-consecutive days and Group 2 trained the abs 6 days per week. The ab exercises increased in difficulty every 4 weeks and speed was regulated by a metronome.

The results surprised even the researchers. NONE of the 3 groups of exercisers demonstrated any strength gains. Nor did they reduce their waist circumference or percentage of body fat.

McGill suggests replacing sit-ups with exercises to strengthen the core while not bending the spine. Sample exercises include bridges, planks, bird dogs and "stir the pot" (this is a complex movement: moving shoulders in a small circle while in a prone push-up position with forearms balanced on an exercise ball).

Apparently, the U.S. Army has been listening to McGill.

One of the key components of the U.S. Army's physical fitness test is a 2 minute sit-up test. To prepare for this testing, army recruits will typically incorporate the sit-up in to their daily training protocol.

Due to the research indication that traditional sit-ups (and variations) may have negative effects on lower back health, the Army initiative the Prevention of Low Back Pain in the Military Clinical Trial (PLBPMCT). The study sought to find if using core exercises versus traditional exercises had any impact on the 2 minute sit-up test.

The PMBMPCT involved 1,467 soldiers (mean age of ~ 21 years; 73% male; 27% female) amongst 12 Army companies. Each company was assigned to complete either sit-up or core training for 5 minutes per day, 4 days per week.

Those performing the sit-up workout followed these exercises
1. Sit-ups
2. Sit-ups with left trunk rotation
3. Sit-ups with right trunk rotation
4. abdominal crunch5. sit-ups

Those performing the core workout followed these exercises
1. Abdominal "draw-in" crunch
2. Left and right side planks
3. Wood choppers
4. Glute bridges5. Bird dog

This exercise routine was followed for a total of 12 weeks after which participants performed the 2 minute sit-up test. At the completion of the study final test scores were compared to test stores obtained just prior to starting the 12 week training program. The final results indicated that core training was just as effective as traditional sit-up programs at improving performance in the 2 minute sit-up test.

Conclusion

There are many reasons to exercise your core. If your goal is to find your "six-pack", your time and effort would be better spent on fine tuning your diet. However, if you're looking to increase athletic performance and mitigate lower back injury, core exercises will surely benefit you.

As for 'the best' core exercises? As always, exercise selection should be geared towards the individual.

With that said, it seems that the exercise ball may just be your best friend when it comes to an effective ab workout.

According to the Oct 2009 study published in the Journal of Bodywork and Movement Therapies, muscle activity was much greater when exercises were performed on a Swiss ball in comparison to a stable surface.

The exercise ball consistently had significantly more rectus activation than the vurl-up on the floor. The chart below provides the percent of maximal contractions of each portion of the abdominals during each exercise

Train hard; stay strong; stay injury free!

Peace.

Susan

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