Six weeks of plank exercise had an effect on muscle mass and muscle activity. In particular, 4 weeks after the start of the plank exercise showed a significant effect, and even after stopping the plank exercise showed a significant result until 2 weeks. In addition, the pectoralis major, erector spinae and rectus abdominis which are mainly used for chest compressions, had a significant effect from 3 weeks after the start of the plank exercise and even after stopping the plank exercise showed a significant result until 4 weeks. These results showed the same results as the present study showing the increase in muscle activity in the major muscles including the abdominal muscle in a previously published study of muscle activity during plank exercise [13].
Analyzing the depth of chest compressions of the study participants, it showed a significant increase after 5 weeks of starting the plank exercise, and after 3 weeks of stopping the plank exercise, it did not become effective chest compression and continued to decrease afterwards. Although chest compression proficiency increases with increasing rate of chest compressions, the decrease in chest compression depth after stopping plank exercise is considered to be due to the change of muscle mass following plank exercise. As the activity of trunk muscles, which is mainly used for chest compression, increases the chest compression depth, which is a high level of force, through the plank exercise. In addition, the previous study showed a rapid increase rate from 4 weeks to 6 weeks after the start of exercise. Since then, there is no significant change in the increase rate. According to these results, in order to achieve effective chest compression depth through plank exercise, plank exercise should be continued for at least 5 weeks, and should not have a break period of at least 2 weeks. As a result of analyzing the change in the rate of chest compressions, there was no significant result about the number of chest compressions by the plank exercise. This is because the depth of chest compression decreases significantly over time in several published studies, but the number of chest compressions is relatively free from problems such as physical consumption compared to chest compression. Incomplete chest compression recoil showed the highest duration of exercise in the effect of chest compression through plank exercise. However, 5 weeks after stopping the plank exercise, the incomplete recoil of chest compressions increases again, and it is thought that the plan should be continued for at least 4 weeks for effective chest compressions and there should be no break of at least 4 weeks. As a result of analyzing the chest compression maintenance time, as shown in the result of analyzing the incomplete chest compression rate, the plank exercise seems to be a result of the significant improvement of muscle endurance. In addition, the effective chest compression success rate increased significantly after 5 weeks of starting exercise, and significantly increased after until 2 weeks of stopping exercise. This means that the maintenance time to chest compression has been increased to the chest compression depth recommended by the 2015 AHA Guidelines. The plank exercise not only increased the maintenance time for chest compression, but also increased the maintenance time for effective chest compressions, which is practically helpful for cardiac arrest patients.
The results of this study showed that for effective chest compressions, plank exercise was effective in increasing proper chest compression depth and muscle endurance for chest compressions. Through this, plank exercise is expected to be effective for long-term chest compression, and furthermore, it can reduce muscle fatigue by centering the trunk muscle.
The limitations of this study are first, the number of study participants is difficult to generalize to 30, and secondly, the use of educational mannequins, it did not accurately reflect the anatomy of the chest. Third, it was that the laboratory was familiar to the participants, not the actual emergency. Fourth, the condition regarding diet that could affect muscles was not considered. Fifth, there is a possibility that psychological factors that subjects can speculate and control the results of research due to continuous experiments. Sixth, the study participants were composed of college students in their twenties and did not reflect the change according to age.
In conclusion, it was found that there was a positive effect on effective chest compressions when the chest compression was performed after training trunk muscles using plank exercise. It is recommended to perform 3 sets of one set(every 10 times for 30 seconds exercise and 20 seconds rest) for 5 weeks as a plank exercise. Unless you have a period of up to two weeks of inactivity, it may be helpful in out-of-hospital cardiac arrest situations where mechanical chest compressions are not available.