|Year : 2022 | Volume
| Issue : 1 | Page : 68-73
Evaluation of EMG activity of superficial respiratory muscles and vital capacity parameters during different pelvic tilts in standing, sitting and lying postures
Sarika Chaudhary1, C Harish2, Sharnpreet Kaur1, Shweta Shenoy1
1 MYAS-GNDU Department of Sports Sciences and Medicine, Guru Nanak Dev University, Amritsar, Punjab, India
2 Acrophase Lab, Indian Institute of Technology Madras, Chennai, Tamil Nadu, India
|Date of Submission||31-Jan-2022|
|Date of Decision||24-May-2022|
|Date of Acceptance||27-Jun-2022|
|Date of Web Publication||30-Jul-2022|
Dr. Sarika Chaudhary
MYAS-GNDU Department of Sports Sciences and Medicine, Guru Nanak Dev University, Amritsar - 143 005, Punjab
Source of Support: None, Conflict of Interest: None
Background: Postures such as kyphosis and lordosis of the spine affect the vital capacity parameters. These spinal alignment alterations may enhance the efficacy of the respiratory muscle contraction and the volume of air available in the lung.
Aim: To examine the effects of different pelvic tilt positions in varying postures on the vital capacity parameters and respiratory muscles.
Setting and Design: This was a cross-sectional one-way repeated measures design. The study was conducted at MYAS-GNDU Department of Sports Sciences and Medicine, GNDU, Amritsar.
Subjects and Methods: Twenty healthy male individuals aged between 18 and 24 years participated in the study. Forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), FEV1/FVC, and peak expiratory flow (PEF) were measured using Spiro Excel when performing anterior, posterior, and neutral pelvic tilts in standing, sitting, and lying postures, and their superficial respiratory muscle activity was measured with surface electromyography.
Statistical Analysis: Repeated measures analysis of variance was applied and Bonferroni correction was used for post hoc analysis.
Results: There was a significant difference in FVC and FEV1 during standing, sitting, and lying postures in all pelvic tilts, with the highest in sitting. Whereas, FEV1/FVC showed a significant difference when performing anterior and posterior tilts in standing, sitting, and lying, with the highest in standing. Increase in PEF was only seen in posterior pelvic tilt in sitting. External oblique muscle showed a significant activity in standing, lying, and sitting with varying pelvic tilts.
Conclusion: The sitting posture could be more effective for pulmonary rehabilitation due to increased vital capacity, followed by standing and lying.
Keywords: Electromyography, pelvic tilt, posture, respiratory muscles, spirometry, vital capacity
|How to cite this article:|
Chaudhary S, Harish C, Kaur S, Shenoy S. Evaluation of EMG activity of superficial respiratory muscles and vital capacity parameters during different pelvic tilts in standing, sitting and lying postures. Indian J Phys Ther Res 2022;4:68-73
|How to cite this URL:|
Chaudhary S, Harish C, Kaur S, Shenoy S. Evaluation of EMG activity of superficial respiratory muscles and vital capacity parameters during different pelvic tilts in standing, sitting and lying postures. Indian J Phys Ther Res [serial online] 2022 [cited 2023 Feb 5];4:68-73. Available from: https://www.ijptr.org/text.asp?2022/4/1/68/353011
| Introduction|| |
Biomechanical alteration of posture alignment influences the lung compliance by changing articular movement of breathing and also by affecting the range of motion, position, and coupling patterns of articulation between the thoracic spinal vertebrae and ribcage. The diaphragm muscle also contributes to the spine stability and ribcage movement. The available literature explains the significant correlation between posture and pulmonary functions. According to Lin et al., a correlation exists between the increased lumbar lordosis and increased forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV1). These spinal alignment alterations may enhance the efficacy of the respiratory muscle contraction and the volume of air available to the lung. Katz et al. reported that PFT is influenced by the body position, but according to the type of population, the optimal position and the magnitude of benefit varies. In standing posture, the vital capacity values get increased due to increased vertical diameter of the thorax and increased lung compliance as compared to sitting and right and left lateral lying positions. The FVC and FEV1 maximal static inspiratory and expiratory pressures of healthy individuals showed a significant variation as a result of change of postures such as sitting erect, sitting lean forward, and supine as it got decreased significantly as they moved from sitting to supine and prone positions., The knowledge of body position, which influences the respiratory system, can give health-care professionals a better understanding of optimal positions for patients with respiratory disorders.
In different postures, the pelvic tilt also influences the pulmonary functions, when the pelvis is tilted anteriorly, the lordosis of the lumbar vertebra is increased, and kyphosis of the thoracic vertebra is decreased. Lordosis of the lumbar vertebra is decreased and kyphosis of the thoracic vertebra is increased when the pelvis is tilted posteriorly. Hwang and Kim reported that peak expiratory flow (PEF) value was greater in neutral position when compared to anterior pelvic tilt and FEV1 was also greater in neutral position when compared to anterior and posterior pelvic tilts. Whereas, on the contrary, Jang and Lee suggested that during respiration, anterior pelvic tilt could be more beneficial for vital capacity and respiratory muscle activation.
The functional and electrical activity of respiratory muscles is assessed with electromyography (EMG) which collects electric signal from the contraction of the muscle, controlled by the nervous system. EMG signals are also considered electrophysiological signals and they are most useful in both medical and rehabilitation fields. The available literature explains that in supine position, the diaphragm strength is negatively reduced and in addition the length of inspiratory muscles, but it is in less optimal position, affecting the length–tension relationship.
There is voluminous amount of literature, which describes the effect of posture on the vital capacity parameters, but there is a scarcity of literature that how variation in pelvic tilts affects the vital capacity. Previous literature states that kyphosis of the thoracic vertebra and lordosis of the lumbar vertebra along with other curves of the spine affects the lung capacity. However, the evidence is not sufficient to support this observation and there is a need to explore more about vital capacity parameters during change in posture and pelvic tilts. As respiratory muscles also play a major role in pulmonary rehabilitation, the magnitude of electrical activity of these muscles is also important. Therefore, the purpose of the present study was to compare the vital capacity parameters during anterior, posterior, and neutral pelvic tilt positions in standing, sitting, and lying postures as well as to assess the superficial respiratory muscle activation with EMG.
| Subjects and Methods|| |
This was a cross-sectional one-way repeated measures study. The sample size was calculated using G-Power with effect size of 0.8. Twenty healthy individuals regularly involved in physical activity were selected by convenient random sampling technique. Subjects aged between 18 and 24 years and body mass index (BMI) between 18.5 and 22.9 (Asian criteria) and having no spinal deformity and postural abnormality were included in the study. Subjects with respiratory disease, recent abdominal surgeries, fractures around the pelvis and hip, or any other inflammatory disease were excluded from the study. The data were collected in a period of 1 month (November 2020–December 2020). The study was approved by the institutional ethics committee, No. 41/HG Dated March 13, 2020. The signed consent form was obtained from all the participants before the study. As the study was performed during the COVID-19 pandemic, the Centers for Disease Control and Prevention guidelines were followed for precautions and proper care had been taken.
Instrumentation and procedure
To measure the FVC, FEV1, FEV1/FVC, and PEF, computerized spirometry (Spiro Excel 1.3) was used. Before taking measurement, the subjects were explained and demonstrated how to perform anterior, neutral, and posterior pelvic tilt in standing, sitting, and lying postures, and also, they were asked to practice the computerized spirometry equipment before reading. Before measuring the lung capacity, the subjects were given visual feedback through a monitor by showing their graph. The subjects made a tight seal with lips onto the mouth piece with nose clip attached to their nose. After breathing normally, they were instructed to slowly expire until their lungs are empty and then take a deep inspiration followed by forceful expiration. The lung capacities were measured in anterior, neutral, and posterior pelvic tilts during standing, sitting, and lying postures [Figure 1],[Figure 2],[Figure 3]. They performed the maneuver three times and the best value was considered. To prevent muscle fatigue between different pelvic tilts, a rest period of 1 min was given, whereas a rest of 5 min was given between different postures.
|Figure 1: Standing posture: (a) Neutral pelvic tilt, (b) anterior pelvic tilt, and (c) posterior pelvic tilt|
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|Figure 2: Sitting posture: (a) Neutral pelvic tilt, (b) anterior pelvic tilt, and (c) posterior pelvic tilt|
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|Figure 3: Lying posture: (a) Neutral pelvic tilt, (b) anterior pelvic tilt, and (c) posterior pelvic tilt|
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The activity of respiratory muscles was measured with a wireless EMG system (Noraxan DTS EMG system, software Myomotion MR 3.8 USA). The landmark was shaved (if required) and cleaned with alcohol before the electrode placement. To measure the muscle activity, pairs of electrodes were placed unilaterally on the right side of the sternocleidomastoid (SCM), scalene (SC), external intercostal (EIC), rectus abdominus upper and lower, and external oblique (EO). The electrode placement for each muscle is shown in [Figure 3]. The signals were rectified and band pass filtered and smoothen (1000 ms) before being recorded digitally at 2000 samples per second and then the root mean square (RMS) value was calculated. To standardize each muscle's RMS values, the maximal voluntary contraction was normalized as percentage. The hand placement for assessing maximal voluntary isometric contractions was performed. Maximal voluntary isometric contractions were performed for 10 s, three times, and the best was quantified using the RMS.
The descriptive statistics was used to analyze the mean and standard deviation of the age, height, weight, and BMI. To compare the change in vital capacity values and activity of superficial respiratory muscles during different tilts and postures, one way ANOVA was applied. Bonferroni test was used for post hoc analysis.
| Results|| |
Statistical analysis was performed with SPSS version (SPSS V IBM, Chicago, U.S.A). Statistical significance was attributed to P < 0.05. The descriptive statistics of the subjects is mentioned in [Table 1]. The comparisons of FVC, FEV1, FEV1/FVC, and PEF values in different postures during different pelvic tilts are demonstrated in [Table 2],[Table 3],[Table 4],[Table 5], respectively.
|Table 2: Analysis of variance showing comparison of forced vital capacity values in different postures during different pelvic tilts|
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|Table 3: Analysis of variance showing comparison of forced expiratory volume in 1 s values in different posture while different pelvic tilts|
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|Table 4: Comparison of forced expiratory volume in 1 s/forced vital capacity ratio by repeated analysis of variance in different position in different pelvic tilt positions|
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|Table 5: Repeated analysis of variance showing the comparison of peak expiratory flow values in different position while in different pelvic tilt positions|
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[Table 2] shows that there was a significant difference in FVC when performing different pelvic tilt positions during standing, sitting, and lying (P < 0.00). Bonferroni post hoc test showed that the difference was highly significant between sitting and lying in neutral and anterior pelvic tilts. Whereas, in posterior pelvic tilt, the differences were highly significant between lying and sitting as well as lying and standing.
[Table 3] shows a significant difference in FEV1 during different postures in different pelvic tilts (P < 0.05). Bonferroni post hoc test showed a highly significant difference between lying and sitting. Whereas, during anterior and posterior pelvic tilts, the differences were more significant between lying and sitting as well as lying and standing.
[Table 4] shows that in case of FCV/FEV1, there were significant differences in anterior and posterior pelvic tilt during sitting, standing, and lying postures (P < 0.05), but Bonferroni post hoc test showed that the magnitude of difference between them was less.
[Table 5] shows the comparison of peak expiratory flow value in different pelvic tilts during different postures, where a significant difference was observed only in case of posterior pelvic tilt (P < 0.05). Bonferroni post hoc test identified significant differences between standing and lying as well as sitting and lying postures.
| Discussion|| |
The main objective of the study was to find out how the varying pelvic tilts in different postures affect vital capacity parameters of the lungs and respiratory muscles. The primary outcomes of the study are as follows: FVC and FEV1 showed significant differences during standing, sitting, and lying postures in all pelvic tilt positions with the highest in sitting, whereas PEF showed a significant difference during posterior pelvic tilt only (P < 0.001). These findings are in consistent with the Patel and Thakar who observed that when spirometric values were compared between sitting and standing, the measurements of FVC, FEV1, and PEF were significantly higher in the sitting position as compared to standing. Dean evaluated the changes in ventilation and perfusion in subjects during different postures and found that in sitting position, base-to-apex ratios for the distribution of ventilation and perfusion were increased, which resulted in an improved efficiency of the lung functioning.
In the present study, FEV1/FVC showed a significant difference in standing, sitting, and lying during anterior and posterior pelvic tilt, with the highest value in standing (P < 0.03). These observations are concurrent with Myint et al. who found that FEV1/FVC values were higher in standing, followed by sitting posture in asthmatic patients. The increase in vital capacity values in standing posture is related to increased volume of the thoracic cavity. The vertical diameter of the thorax is also increased because the abdominal contents are pulled down as a result of gravity. The length–tension relationship of the expiratory muscles is more in the optimal region, which results in higher intrathoracic pressures and generate forceful expiration.
In lying, the compliance of the ribcage is decreased due to the compression effect of the gravity along its anteroposterior diameter. The diaphragm generally faces an increased pressure caused by the abdominal organs in supine as compared to sitting and the chest wall mobility is limited on the dorsal side due to the weight.
In the present study, the secondary outcomes are as follows: FEV1/FVC showed a significant difference (P < 0.03) during different pelvic tilts in lying, with the highest in neutral position followed by anterior pelvic tilt. These findings can be explained on the basis of the study done by Hwang and Kim, which reported that when the pelvis is in neutral position, the spirometry values are increased due to increased activation of the diaphragm and inspiratory muscles. When the pelvis is tilted anteriorly, it causes the stretching of the abdominal muscles beyond its anatomical resting length, resulting in optimal length–tension relationship of the muscle. When pelvic tilts were compared for the activation of SC, SCM, rectus abdominis upper and lower, EICs, and EO in standing, sitting, and lying with the help of EMG, the EO muscle showed a statistically significant difference (P < 0.05) in anterior, neutral, and posterior pelvic tilt in standing, sitting, and lying [Figure 4]. These observations are also supported by Kera and Maruyama that the significant difference in EO muscle activity during the expiration is due to differential anatomical arrangement of this muscle. Whereas, other muscles showed a minimal variation, but the differences are not statistically significant. These results are in consistent with the findings of Ogiwara and Miyachi who reported that respiratory muscle strength did not change in sitting, half lying, slumped' half lying, supine lying, right side lying, and left side lying in 20 young subjects. The inspiratory and expiratory muscle strength showed no change with alteration of body positions.
|Figure 4: The comparison of EMG muscle activity of external oblique muscle in different postures with neutral, anterior, and posterior pelvic tilts. EMG: Electromyography|
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The current study revealed that pelvic tilts and postures have no influence on respiratory muscle activation, except EO muscle, in different pelvic tilt positions during standing, sitting, and lying. Although the differences were statistically significant, the magnitude of difference during variation in pelvic tilts and postures for vital capacity parameters as well as respiratory muscles was small in healthy individuals. This observation can be supported on the basis of length–tension relationship, which remains the same and muscles work with equal efficiency irrespective of any posture in healthy individuals.
Due to the pandemic and lack of availability of subjects, the study was done on small sample size of males only. It is recommended that future studies can be done on large sample size. It is further recommended that further studies can also be done on populations of different respiratory disorders and different age groups.
| Conclusion|| |
There was a significant difference in FVC, FEV1, and FEV1/FVC by changing pelvic tilt positions during different postures although the amount of difference was very small. Whereas, respiratory muscle activity is not affected by variation in pelvic tilts and postures except EO muscle. Hence, keeping in view of COVID-19 pandemic situation, it can be suggested that the spirometry measurements and respiratory rehabilitation given in any posture can be beneficial for the patients as breathing exercise given in any posture can make a difference to health of the patient. Serial studies can be conducted with large sample size on variation in pelvic tilts and pulmonary function for greater precision.
The authors gratefully accept the contributions of all of the volunteers who took part in this research.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5]