An electromyographical evaluation of the validity of the 2-minute sit-up section of the Army physical fitness test in measuring abdominal strength and endurance

Military Medicine, Nov 2002 by Szasz, Anna

Limitations

- The sample is convenient, not random. Only students enrolled in the Reserve Officer Training Corps program at the University of Scranton were included.

- The sample size is small. There were 34 participants, but only data for 28 participants could be used due to problems with the electrodes picking up muscular activity.

- The EMG picks up muscular activity on the surface of the skin and is not invasive.

- The researchers assessed only one of the abdominal muscles and one of the hip flexors. Also, the hip flexor being examined is not the major muscle responsible for hip flexion.

Conclusion

The researchers hypothesized that as the test progressed, the relative value of the rectus abdominus activity would decrease, whereas the relative value of the rectus femoris would increase. By use of electromyographic equipment and electrodes placed over the rectus abdominus and the rectus femoris, the electrical activity of these muscles was monitored throughout the 2-minute sit-up test.

Our results demonstrated that as the test progressed, both the abdominal and the hip flexor activity increased as measured by area of contraction. Initially, the relative value of the abdominal muscles was higher than that of the hip flexors. However, as the test continued, the relative value of the hip flexor activity increased at a greater rate, confirming that they were used to a greater degree. The researchers found statistical significance when comparing this change in hip flexor activity throughout the test to the change in abdominal activity. This might indicate that the participant may have performed the sit-up incorrectly; nevertheless, within the scope of the 2-minute, timed sit-up test, it counted as a correctly performed sit-up.

Discussion

Maintaining good posture is important for all individuals, especially physically active people, such as those in the military. Both back extensors and abdominals need to work together to maintain good posture. Although most individuals have adequate back extensor strength and endurance, most individuals have poor abdominal strength and endurance.3 Abdominal muscles need to be able to resist the pull of the hip flexor muscles so that the pelvis and spine will not develop poor alignment. Because of the importance of the abdominal muscles in the maintenance of good posture, different organizations, such as the military, develop tests designed to measure abdominal endurance. The data obtained by the researchers as a whole indicated that high scores on the sit-up portion of the APFT did not necessarily correspond with abdominal endurance.

An alternative method of assessing abdominal endurance is the curl-up or crunch. If done properly, crunches mainly use abdominal musculature because no active hip flexion is required to partially curl the trunk. Because sit-ups are a required portion of the APFT, members of the army need to perform this exercise frequently to prepare for the test. Recently the Army Times, a weekly newspaper, contained an article regarding the use of the sit-up in the APFT. According to Dr. Robert A. Arciero, an orthopedic surgeon who is a retired army colonel with 24 years of service, "Almost every military orthopedic surgeon will tell you they've had many troops complain of back and diskrelated complaints, like numbness and tingling in the leg, when they do sit-ups." Other branches of the military have already switched from the sit-up to the curl or crunch. The reason the army still uses the sit-up is tradition, ease of administration and scoring, and no need of special equipment. The army also stated that there is currently insufficient research to correlate sit-ups with low back problems or that it is not a valid assessment of abdominal endurance.8 The researchers wanted to demonstrate that the sit-up is not a valid assessment of abdominal endurance. The findings of this study support that the sit-up portion of the APFT does not accurately measure abdominal endurance. Some of the researchers' suggestions for further research include the following. They suggest a correlation between scores on the sit-up test with incidence of low back problems. They also suggest a correlation between scores and levels of electrical activity of hip flexors and abdominals. They further suggest a correlation between scores and hip flexor tightness. Finally, the army should investigate the validity of alternate measures of abdominal strength.