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The straining burden of defecation needs to be alleviated in individuals with defecation difficulties due to constipation, those with heart disease or cerebrovascular diseaseclients, the elderly with reduced abdominal muscle strength, and pregnant women. To provide nursing assistance for defecation, a toilet posture that permits effective straining and reduces the physical burden of defecation must be investigated. The aim of this study was therefore to elucidate the straining effects and physical burden of different toilet defecation postures.
Methods:
1. Subjects: Twenty healthy women (20.9 ± 0.8 years) with no straining restrictions.
2. Experimental method:
1) Procedure: Subjects sat on a portable toilet. In the first test, the subjects sat quietly with their spine at a 90° angle to the sitting surface (basic posture) for 3 min before straining for 8 sec. Thereafter, they rested in the basic posture for 5 min. Next, they sat with their spine tilted 60° to the sitting surface for 1 min before straining for 8 sec. They then returned to the basic posture and rested for 5 min. Measurements were conducted sequentially at different postural angles (45°, 30°) using the same pattern.
2) Measurement items:
(1) Electromyography
Electromyography (EMG) was performed to elucidate the differences in the amount of muscle strength used to strain during defecation according to toilet posture. Probes to measure electromyography were attached to (1) the external oblique muscle and (2) the internal oblique muscle, which are used during straining, and (3) the erector muscles of the spine, which are necessary to maintain posture.
(2) Electrocardiography
Heart rate variability was measured to determine physical burden during straining.
(3) Blood flow
Infrared probes were attached to the lateral sides of the head to measure blood flow as an indicator of physical burden during straining.
3. Analysis methods:
1) Root mean square processing was used to analyze EMG. The integral values extracted during the 3-sec period around the maximum value were used as analysis data. Baseline values at each EMG measurement site before straining for each angle were compared. The Kruskal–Wallis test was used for statistical analysis.
2) The inter-beat interval (IBI) before, during, and after straining was extracted for each angle to be used for electrocardiography (ECG) analysis. The Friedman Test followed by a multiple comparison was used for statistical analyses.
3) For blood flow, data obtained during the 8-sec period before, during, and after straining were extracted. Measured values were converted into integral values and used as analysis data. The Friedman Test followed by a multiple comparison was used for statistical analyses.
The level of significance was set at 0.05 for all tests.
Results:
Comparison of baseline EMG values for the erector muscles of the spine at 30° and 90° revealed a significant difference (P = 0.05). Each postural angle was also compared according to the measurement site, which revealed no significant differences between angles at any of the sites.
The IBIs before and during straining at 45° (P = 0.032) were significantly different. A significant difference was also seen between those before and during straining at 90° (P = 0.032).
Blood flow after straining at 90° was found to have significantly increased as compared to that before straining at 90° (P = 0.005). Furthermore, a significant increase in blood flow after straining at 30° was also observed as compared to that during straining at 30° (P = 0.023).
Conclusion:
No change in the amount of muscle strength exerted during straining was found between the different toilet defecation postures tested. The increase in blood flow after straining is considered to have been caused by a hyperemic reaction after reduced blood flow due to vasoconstriction caused by the burden of straining. Because this study was conducted in healthy, young subjects, muscle strength may have been exerted more effectively and the resilience to the burden may have been greater in all toilet postures. Therefore, a future study will need to investigate a toilet defecation posture that allows effective exertion of strength and reduces the physical burden in elderly individuals with diminished abdominal muscle strength.