Popularity of Crunches
While the quest for the highly visible “six-pack abs” is in the minds of most exercisers the likelihood of the achievement is similar to a high school athlete earning a Division I scholarship in collegiate sports. Some elite athletes with the right genetics and work ethic will reach it, but most will not even come close. Part of the mystique behind the attractiveness is the idea that anyone can get lean enough to see the definition of the rectus abdominis. This is evident by the inundation of infomercials touting spot reduction from the latest fitness fantasy gimmick. According to the television experts if you flex your trunk enough times the abs will come right out as inches of fat disappear. While it seems laughable to anyone who is educated, preying on the ignorant is unfair and demonstrates the level of consumer protection afforded to Americans.
The infomercial education system has made its way into the gym and whether you call them crunches, sit-ups, curl ups or their variations have limited effect on the ability to actually get a “six pack”. Certainly abdominal curl-ups performed with loads and bodybuilding rep schemes will enhance development of the rectus abdominis, but even the most popular abdominal exercises will not produce visible results unless made part of a comprehensive fitness plan that includes specific weight loss activities and proper nutrition. Since you cannot selectively burn fat from particular locations by performing exercises that target a specific area of the body, total fat loss is the key. In fact, for most people nutrition is likely the most important component because it is easier to manage calories through diet than exercise. Skip one alcoholic drink and it equates to running 2-3 miles. This explains why most of the fitness gadgets and ab classes are ineffective for developing leanness; they may target the abs, but without participating in activities that increase overall caloric expenditure and eating a very clean diet, the ability to attain a lean midsection is not a likely outcome.
From a personal training perspective there are many better exercises for function and performance than ground-based ab flexion. Much like planks, limited-range ab isolation in the supine position is often better used by people who are just getting started with an exercise program because they can help teach activation. However, unless you are a bodybuilder attempting to isolate certain muscle groups, the exercises should progress to increase the challenge to the abdominals for improved function. Doing multiple sets of ten repetitions of crunches will not provide the same beneficial effects that a variety of trunk movements performed in the closed kinetic chain will offer. In addition, people must be careful to emphasize abdominal functional to prevent lower back issues, as muscular imbalances can result in pain and injury.
Due to the tendency to sit in a slightly slumped position, the C-spine associated with desk sitting the majority of the day causes the abdominals and hip flexors to become short. Using crunches as the sole abdominal movement perpetuates this position. Anchor the feet and the hip flexors become dominant, so switching to anchored sit-ups doesn’t help and for most people full flexion is contraindicated due to the excessive pull on the lumbar and iliac spine by the psoas major and iliacus. This can place additional stress on the low back or cervical spine if a person laces their fingers behind their head and then pulls to flex forward. But just like food, ground-based abdominal exercises aren’t always a bad selection and may vary in benefit among different people; the proper use of selected movements can help build strength in the abdominal area, and they can be a great starting point for individuals with low back issues. Properly performed crunches may actually benefit individuals with back/front imbalance, because the basic movement helps to strengthen the abdominals and some stretch the muscles of the low back, which are often tight from poor posture or other degenerative conditions. For fit individuals, exercises such as plate-loaded crunches, bicycles, and v-ups isolate certain sections of the abdominal wall, and can be good choice for people who are seeking hypertrophic gains. For most people however, functional exercises such as pelvic bridges, quadrupeds, and varied-angle trunk rotation can join asymmetrically-loaded or overhead exercises in engaging the trunk as a whole; thereby teaching the abdominal muscles to work in conjunction with the obliques and muscles of the low back to help functionally stabilize the spine and improve overall posture. For advanced exercisers, medicine ball chops and throws or isolative movements for muscle development like the hanging knee raises to posterior pelvic tilt and roll-outs provide additional challenges. When it comes to abdominal training for vanity, the first consideration is body composition; for performance it is integrated function and connectivity; for health it is muscle balance. Keeping these things in mind may help with the idea of programming for purpose rather than perpetuating common gym folklore.