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Fisioterapia e Pesquisa

versão impressa ISSN 1809-2950

Fisioter. Pesqui. vol.21 no.4 São Paulo out./dez. 2014

http://dx.doi.org/10.590/1809-2950/12463321042014 

Original Research

Respiratory muscle strength and thoracoabdominal mobility in sedentary elderly, adults and players of adapted volleyball: a pilot study

Força muscular respiratória e mobilidade toracoabdominal em idosos e adultos sedentários e praticantes de voleibol adaptado: estudo-piloto

Fuerza muscular respiratoria y la movilidad tóraco-abdominal en ancianos y adultos sedentarios y practicantes de voleibol ajustado: estudio piloto

Letícia Baltieri 1  

Laisa Antonela dos Santos 2  

Gustavo Nazato Furlan 3  

Marlene Aparecida Moreno 4  

1Universidade Estadual de Campinas (UNICAMP) - Campinas (SP), Brazil

2UNIMEP - Piracicaba (SP), Brazil

3Centro Cultural e Recreativo Cristóvão Colombo de Piracicaba - Piracicaba (SP), Brazil

4Programa de Pós-graduação em Fisioterapia, UNIMEP - Piracicaba (SP), Brazil

ABSTRACT

A number of modifications accompany the aging process, including changes in the respiratory system. However, regular physical activity may be an effective way to prevent these alterations. The purpose of this study was to evaluate and compare the thoracoabdominal mobility and respiratory muscle strength, in sedentary individuals and in those who participate in adapted volleyball. Subjects aged 50 and 80 years old that were participating in adapted volleyball for at least one year, and sedentary ones who neither smoked nor presented pulmonary, cardiovascular or musculoskeletal diseases were evaluated for thoracoabdominal mobility by cirtometry at the axillary (CAx), xiphoid (CX) and abdominal (CAb) levels. They were also assessed for respiratory muscle strength by measuring their maximal respiratory pressures (MIP and MEP). The active group had greater values ​​of cirtometry compared to the sedentary group (56.4% higher in CAx, 83.4% in Cx and 63.5% in CAb) and higher values ​​of MEP (41.3% higher in absolute MEP and 39.5% of MEP in predicted %). The MIP (cmH2O and predicted %) did not differ between groups. Participation in adapted volleyball may have contributed to maintained thoracicoabdominal mobility and expiratory muscle strength in these elderly and adults.

Key words: Respiratory Mechanics; Aging, Breath Tests; Physical Therapy Modalities; Volleyball

RESUMO

Uma série de modificações acompanham o processo de envelhecimento, incluindo mudanças no sistema respiratório. No entanto, atividade física regular pode ser uma maneira eficaz de prevenir estas alterações. O objetivo deste estudo foi avaliar e comparar a mobilidade toracoabdominal e a força muscular respiratória em sedentários e praticantes de voleibol adaptado. Foram incluídos indivíduos entre 50 e 80 anos de idade, que praticam voleibol adaptado há pelo menos um ano, e sedentários não tabagistas e sem doenças pulmonares, cardiovasculares ou musculoesqueléticas. Foram avaliadas a mobilidade toracoabdominal, por meio da cirtometria axilar (CAx), xifoideana (CX) e abdominal (CAb), e a força muscular respiratória por meio das medidas de pressões respiratórias (PI máxima e PE máxima). O grupo ativo apresentou valores de cirtometria maiores em relação ao sedentário (56,4% maior na CAx, 83,4% na CX e 63,5% na CAb), bem como maiores valores da PE máxima (41,3% maior na PE máxima absoluta e 39,5% da PE máxima em % predita). A PI máxima (cmH2O e % predita) não mostrou diferença entre os grupos. Concluiu-se que a prática de voleibol adaptado pode ter contribuído para a manutenção da mobilidade toracoabdominal e força muscular expiratória nestes idosos e adultos.

Palavras-Chave: Mecânica Respiratória; Envelhecimento,Testes Respiratórios; Modalidades de Fisioterapia; Voleibol

RESUMEN

Una serie de cambios acompañan el proceso de envejecimiento, incluso alteraciones en el sistema respiratorio. Sin embargo, la actividad física regular puede ser un modo eficaz de prevenir esas alteraciones. El objetivo de eso estudio fue evaluar y comparar la movilidad tóraco-abdominal y la fuerza muscular respiratoria en sedentarios y practicantes de voleibol ajustado. Fueron inclusos sujetos entre los 50 y 80 años de edad que practican voleibol ajustado por pelo menos un año y sedentarios no tabaquistas y sin enfermedades pulmonares, cardiovasculares o musculoesqueleticas. Se evaluó la movilidad tóraco-abdominal por medio de la cirtometria axilar (CAx), xifoidea (CX) y del abdomen (CAb), y la fuerza muscular respiratoria por medio de las mensuraciones de las presiones respiratorias (PI máxima y PE máxima). El grupo activo presentó valores de cirtometria mayores en relación al sedentario (56,4% mayor en la CAx, 83,4% en la CX y 63,5% en la CAb), así como valores mayores de la PE máxima (41,3% mayor en la PE máxima absoluta y 39,5% de la PE máxima en % predicho). La PI máxima (cmH2O y % predicho) no mostró diferencia entre los grupos. Se concluyó que la práctica de voleibol ajustado puede tener contribuido para la manutención de la movilidad tóraco-abdominal y la fuerza muscular espiratoria en esos ancianos y adultos.

Palabras-clave: Mecánica Respiratoria; Envejecimiento, Pruebas Respiratorias; Modalidades de Fisioterapia; Voleibol

INTRODUCTION

Aging is a dynamic and progressive process that causes changes in all body systems. Structural alterations of the respiratory system due to aging involve the lungs, rib cage, and respiratory muscles, particularly the diaphragm1; whereas functional changes include modifications in lung volume and capacity due to structural alterations2. These may be associated with sarcopenia, i.e. loss of muscle mass due to aging3,which begins at 50 years old and causes losses of 1% per year, increasing to 3% per year after age 60, thus promoting decreased muscle strength4 , 5.

This muscle loss may happen because of interaction of metabolic, physiological, and functional disorders, innervation alterations, decreases in hormones, increased inflammatory mediators, and alteration of protein-calorie ingestion that occurs with aging6 , 7. Thus, aging affects the respiratory system8 and can be seen in reduced spirometric values according to age9, decreased vital capacity, increased residual volume, and decreased mobility of the thoracic wall10 , 11.

Previously studies suggest that diaphragm strength is reduced in the elderly population12. Besides, in spite of its continuous contractile activity during the normal life cycle, the diaphragm presents reduced capacity to generate maximal strength during senescence13.

Nevertheless, considering the effects of aging on the rib cage, there is a decrease in its elasticity, probably caused by the progressive calcification of the involved joints, and also a reduction of intervertebral spaces14, which could be associated with the progressive loss of thoracic mobility during the aging process.

Physical inactivity is currently the fourth most important cause of mortality worldwide. Regular physical exercise is related to lower rates of mortality, heart diseases, high blood pressure, strokes, type 2 diabetes, and cardiorespiratory and musculoskeletal disorders15.

It has been reported that preventive physical exercises is the best way to slow sarcopenia due to aging7 , 16, besides being related to lower rates of other diseases, like previously mentioned15.

Thus, physical training, even if not specifically for the respiratory muscles, promotes increased respiratory muscle strength, which indicates that such decline can be slowed or reverted with the regular practice of physical exercises17.

Due to the systemic alterations that accompany aging, which are aggravated by being sedentary, physical activities and sports are encouraged among this population15. Adapted volleyball became popular with elderly and adults because it is an impact sport, therefore it can be a support to osteogenesis and to prevent osteoporosis18. Furthermore, it involves major muscle groups, particularly those of the upper limbs, which indirectly influence the respiratory system and can interfere in thoracic mobility and respiratory muscle strength19.

Therefore, our hypothesis was that regular participation in adapted volleyball would contribute to preserved thoracoabdominal mobility and respiratory muscle strength in elderly and adults.

The objective of the present study was to evaluate a sample of adults over 50 years of age and compare the thoracoabdominal mobility and respiratory muscle strength of sedentary subjects with that of those who play adapted volleyball.

METHODOLOGY

This study was approved by the Research Ethics Committee of the University of Piracicaba (UNIMEP), protocol number 70/10, and all volunteers signed a free informed consent form.

This was a pilot, cross-sectional and case-control study, in which sedentary and active volunteers who participated in adapted volleyball were evaluated regarding their thoracoabdominal mobility and respiratory muscle strength.

Participants

Volunteers were considered sedentary according to the questionnaire of Baecke et al.20 and were selected from the community, and the active volunteers were recruited from a municipal recreation center. The study included subjects between 51 and 80 years old who were non-smokers, had no diagnosed pulmonary, cardiovascular or musculoskeletal diseases, did not use medications that could interfere with the variables studied and, for the active group, who had been in the training program for at least one year.

Materials and procedure

The active group (AG) activities were carried out twice a week for 90 minutes as follows: an initial stretching period of the muscle groups followed by a warm-up consisting of light running and ball throwing; a training session consisting of net and backcourt tactics; a variety of physical development exercises (abdominals, throwing, technical and tactical training) and, finally, practice matches. A physical educator monitored and scheduled all activities. While standing and shirtless, the volunteers' thorax and abdomen circumferences were measured using cirtometry, following that described by Jamami et al.21.

This method consisted of measuring the trunk circumference with a measuring tape scaled in centimeters at the axillary (CAx), xiphoid (CX), and abdominal (CAb) levels. For the CAx and CX levels, the reference points were the anterior axillary line and the xiphoid process, respectively, and for the abdominal level, it was the umbilicus. The standardized measurement procedure consisted of keeping the zero point of the measuring tape on the midline of the body and horizontally aligned with the respective level, with the other end of the tape loosen to allow its dislocation. The tape was positioned in a way to maintain the soft tissue contours unaltered.

After the subjects were trained, they were instructed to perform maximal inspiration and expiration for each thoracic level evaluated. The measurements were taken at the end of the maximal expiration. The participants held the maximal inspiration and expiration for at least two seconds in order to allow data collection. All measurements were taken three times at each level. The differences between the inspiratory and expiratory ones were calculated, and the mean of the three measurements of each level was used for analysis.

In order to evaluate the maximal respiratory pressure, the equations proposed22 were used to predict the normal values of maximal inspiratory (MIP) and maximal expiratory (MEP) pressures. The respiratory pressures were measured using an analog manovacuometer (GER-AR(r), São Paulo, Brazil) with an operational interval of ±300 cmH2O. Readings of the equipment had been previously checked against a mercury column.

All measurements were collected by the same researcher and carried out using the same verbal commands, with the volunteers seated and having their nostrils occluded with a nasal clip to avoid air leak. The MIP was measured during effort, beginning with the residual volume (RV), whereas the MEP was achieved according to total lung capacity (TLC). Each volunteer performed five technically satisfactory maximal inspiration and expiration efforts, i.e. without perioral air leakage, held for at least one second and of similar values (≤10%), in which the measurement with the highest value was considered in the analysis22.

Statistical analysis

Data were analyzed in the software Statistical Package for the Social Sciences (SPSS), version 13.0. The continuous variables were expressed by central tendency and dispersion, and the categorical ones by frequencies. Shapiro-Wilk's test was used to verify the data normality, and in case of normality, the Student's t-test for independent samples was applied. The chi-square test was used to analyze the categorical data expressed in frequencies. A 5% significance level was adopted for all analyses.

Based on a sample test performed for the MEP pilot values of the present study, using means and standard deviations of both groups, with an 80% power and a 5% significance level, and using the t-test, it was determined that 19 volunteers would be needed in each group. The sample calculation was obtained using the software BioEstat, version 5.3.

RESULTS

Thirty-four volunteers were selected for this study. However, eight were excluded: seven refused to participate and one was a smoker. Therefore, 26 volunteers of both genders took part in this study, with 13 in the Sedentary Group (SG) and 13 in the AG represented in Figure 1.

Figure 1. Flowchart of volunteer participation in the study 

The sample characteristics, presented in Table 1, show homogeneity of the variables. Table 2 presents results for the comparison of dependent variables between groups; the AG had values ​​greater of cirtometry compared to the SG (56.4% higher in CAx, 83.4% in CX and 63.5% in CAb) and higher values ​​of MEP (41.3% higher in absolute MEP and 39.5% of MEP in predicted %). The MIP (cmH2O and predicted %) did not differ between groups.

Table 1. Gender and anthropometrics characteristics of both groups, and period of adapted volleyball practice of the Active Group. The values are expressed in mean and standard deviation 

Variables Active Group (n=13) Sedentary Group (n=13) p-value
Gender (F/M) 8/5 7/6 0.714
Age (years) 64.54±6.2 66.08±9.81 0.637
Body mass (kg) 72.01±11.93 71.15±11.10 0.850
Height (cm) 167.07±7.62 167.84±9.46 0.821
BMI (kg/m2) 25.73±3.59 25.25±3.53 0.734
Time of adapted volleyball practice (months) 54±27.49

F: female; M: male; BMI: Body Mass Index

Table 2. Comparison between thoracoabdominal cirtometry and respiratory muscle strength groups. The values are expressed in mean and standard deviation 

Variables Active Group (n=13) Sedentary Group (n=13) p-value
CAx (cm) 7.15±1.71 4.57±2.41 0.004
CX (cm) 7.19±2.71 3.92±1.69 0.001
CAb (cm) 4.84±2.07 2.96±1.39 0.012
MIP (cmH2O) 87.69±22.78 77.30±8.26 0.135
MEP (cmH2O) 143.07±58.79 101.23±28.93 0.030
MIP (% predicted)a 98.04±15.55 88.11±13.27 0.093
MEP (% predicted)a 155.78±43.63 111.61±23.97 0.004

CAx: axillary cirtometry; CX: xiphoid cirtometry; CAb: abdominal cirtometry; MIP: maximal inspiratory pressure; MEP: maximal expiratory pressure; apredicted percentage based on Neder et al.22

DISCUSSION

Results show that the adapted volleyball group presented greater thoracic and abdominal mobilities and higher expiratory muscle strength levels.

A number of studies has shown the deleterious effects of aging on different systems1 , 12 , 14 , 23 , 24. However, regular physical exercise during the aging process may be related to better functional capacity and quality of life25 , 26, as well as to a delay or an attenuation of the normal deterioration of the respiratory muscle strength, according to maximal respiratory pressures17.

Even though it was not the objective of this study, literature reports that there may be an association between functional capacity27, quality of life for elderly individuals, and respiratory muscle strength28. Results showed that physical activity seems to lessen muscle loss due to the aging process, since the expiratory muscle strength was greater in the AG. These results are corroborated by other studies, showing that physical activity during aging acts as a protective factor against cognitive decline and dementia29 - 31.

A previously study concluded that the aging process is followed by a loss of muscle mass and, consequently, gradative loss of muscle strength and thoracoabdominal mobility; however, these may be lower in individuals who exercise24. In the present study, both groups presented normal values for respiratory muscle strength, according to the equation proposed by Neder et al.22 for a healthy population. Nevertheless, when the absolute values and those as the predicted percentage were compared between the active and the sedentary groups, there was a significant difference regarding maximal expiratory pressure, which was higher for the AG. This could be explained by the type of physical activity performed by the group, since the abdominal muscles are frequently required to perform tasks in adapted volleyball, and such tasks were part of the technical exercises carried out by the studied team19. A research27 showed, like the present study, that physical activity, even when it is not specific for the respiratory muscles, can improve maximal expiratory pressure by working the peripheral muscles.

An investigation demonstrated a progressive and significant reduction of maximal inspiratory and expiratory pressures with aging24 as did the other study, using maximal transdiaphragmatic pressure, which showed losses from 0.8 to 2.7 cmH2O in maximal inspiratory pressure in subjects between 65 and 85 years of age23 , 16. However, even though literature reports a decrease asssociated with aging, no such reduction was found in either group. This fact may be perhaps explained by the age range of the volunteers, whose lower limit was below that of the age range evaluated by the mentioned authors.

Following this same context, it has been reported that there is a reduction in thoracic distensibility with aging14, however, this loss was significantly lower in the AG, as a result of physical exercise, as previously described in a number of studies7 , 17 , 30 , 31.

Rigidity of the rib cage, which occurs with aging, happens due to processes of calcification and arthritis of the costovertebral joint and can lead to a diaphragmatic respiratory pattern32; therefore, individuals may have limitations when subjected to an activity with greater expenditure of energy, since the thoracic muscles are requested. Moreover, with age there is increased thoracic kyphosis due to degenerative factors, both muscle and intervertebral discs, causing even greater restriction of mobility thoracic33.

In the case of the volunteers in this study, adapted volleyball, which combines exercises of the lower limbs and stretching of the musculature that involves the thorax, can contribute to a better posture and movement of the rib cage. They presented up to 83% higher mobility compared to sedentary individuals.

This study was limited by the fact that the ideal number of participants (sample calculation) was not reached, since the sample presented here was part of a single adapted volleyball team with a limited number of players (the recreative center has only 13 participants).

Further studies about this should be conducted in order to verify the benefits of different sports in lung function and its long-term benefits.

CONCLUSION

It can be concluded that physical exercises may have increased the thoracoabdominal mobility in all levels and in the expiratory muscle strength of elderly and adults. This reinforces the idea that physical exercises have beneficial effects on the respiratory system of adults and elderly, attenuating the deleterious effects inherent in aging.

REFERENCES

1. Janssens JP, Pache JC, Nicod LP. Physiological changes in respiratory function associated with aging. Eur Respir J. 1999;13:197-205. [ Links ]

2. Zaugg M, Lucchinetti E. Respiratory function in the elderly. Anesthesiol Clin North America. 2000;18:47-58. [ Links ]

3. Waters DL, Baumgartner RN, Garry PJ, Vellas B. Advantages of dietary, exercise-related, and therapeutic interventions to prevent and treat sarcopenia in adult patients: an update. Clin Interv Aging. 2010;5:259-70. [ Links ]

4. Narici MV, Maffulli N. Sarcopenia: characteristics, mechanisms and functional significance. Br Med Bull. 2010;95:139-59. [ Links ]

5. Zhong S, Chen CN, Thompson LV. Sarcopenia of ageing: functional, structural and biochemical alterations. Rev Bras Fisioter. 2007;11:91-7. [ Links ]

6. Baumgartner RN, Koehler KM, Gallagher D, Romero L, Heymsfield SB, Ross RR, et al. Epidemiology of Sarcopenia among the Elderly in New Mexico. Am J Epidemiol. 1998;147:755-63. [ Links ]

7. Silva TA, Frisoli Junior A, Pinheiro MM, Szejnfeld VL. Sarcopenia associada ao envelhecimento: aspectos etiológicos e opções terapêuticas. Rev Bras Reumatol. 2006;46:391-7. Freitas FS, Ibiapina CC, Alvim CG, Britto RR, Parreira VF. Relationship between cough strength and functional level in elderly. Rev Bras Fisioter. 2010;14:470-6. [ Links ]

8. Tramont CV, Faria AC, Lopes AJ, Jansen JM, Melo PL. Influence of the ageing process on the resistive and reactive properties of the respiratory system. Clinics. 2009;64:1065-73. [ Links ]

9. Meyer KC. Aging. Proc Am Thorac Soc. 2005;2:433-9. [ Links ]

10. Summerhill EM, Angov N, Garber C, McCool FD. Respiratory Muscle Strength in the Physically Active Elderly. Lung. 2007;185:315-20. [ Links ]

11. Tolep K, Higgins N, Muza S, Criner G, Kelsen SG. Comparison of diaphragm strength between healthy adult elderly and young men. Am J Respir Crit Care Med. 1995;152:677-82. [ Links ]

12. Smith WN, Dirks A, Sugiura T, Muller S, Scarpace P, Powers SK. Alteration of contractile force and mass in the senescent diaphragm with b2-agonist treatment. J Appl Physiol. 2002;92:941-8. [ Links ]

13. Oyarzun MG. Función respiratoria en la senectud. Rev Med Chile. 2009;137:411-8. [ Links ]

14. World Health Organization. Global Recommendations on Physical Activity for Health. 2010. [cited 2012 Feb 01]. Available from: http://whqlibdoc.who.int/publications/2010/9789241599979_eng.pdf. [ Links ]

15. Bruusgaard JC, Johansen IB, Egner IM, Rana ZA, Gundersen K. Myonuclei acquired by overload exercise precede hypertrophy and are not lost on detraining. Proc Natl Acad Sci. 2010;107:15111-6. [ Links ]

16. Gonçalves MP, Tomaz CAB, Cassiminho AL, Dutra MF. Avaliação da força muscular inspiratória e expiratória em idosas praticantes de atividade física e sedentárias. Rev Bras Cienc Mov. 2006;14:37-44. [ Links ]

17. Rantalainen T, Linnamo V, Komi PV, Selänne H, Heinonen A. Seventy-year-old habitual volleyball players have larger tibial cross-sectional area and may be differentiated from their age-matched peers by the osteogenic index in dynamic performance. Eur J Appl Physiol. 2010;109:651-8. [ Links ]

18. Zaccagni L, Onisto N, Gualdi-Russo E. Biological characteristics and ageing in former elite volleyball players. J Sci Med Sport. 2009;12:667-72. [ Links ]

19. Baecke JA, Burema J, Friterjs JE. A short questionnaire for the measurement of habitual physical activity in epidemiological studies. Am J Clin Nutr. 1982;36:936-42. [ Links ]

20. Jamami M, Pires VA, Oishi J, Costa D. Efeitos da intervenção fisioterápica na reabilitação pulmonar de pacientes com doença pulmonar obstrutiva crônica (DPOC). Rev Fisioter Univ São Paulo. 1999;6(2):140-53. [ Links ]

21. Neder JA, Andreoni S, Lerario MC, Nery LE. Reference values for lung function tests. II. Maximal respiratory pressures and voluntary ventilation. Braz J Med Biol Res. 1999;32:719-27. [ Links ]

22. Enright PL, Kronmal RA, Manolio TA, Schenker MB, Hyatt, RE. Respiratory muscle strength in the elderly. Correlates and reference values. Cardiovascular Health Study Research Group. Am J Respir Crit Care Med. 1994;149:430-8. [ Links ]

23. Simões RP, Auad MA, Dionísio J, Mazzonetto M. Influência da idade e do sexo na força muscular respiratória. Fisioter Pesq. 2007;14:36-41. [ Links ]

24. Matsudo SM, Matsudo VK, Barros Neto TL. Atividade física e envelhecimento: aspectos epidemiológicos. Rev Bras Med Esporte. 2001;7:2-13. [ Links ]

25. Watsford ML, Murphy AJ, Pine ML, Coutts AJ. The Effect of Habitual Exercise on Respiratory-Muscle Function in Older Adults. J Aging Phys Activ. 2005;13:3-4. [ Links ]

26. Simões LA, Dias JM, Marinho KC, Pinto CL, Britto RR. Relação da função muscular respiratória e de membros inferiores de idosos comunitários com a capacidade funcional avaliada por teste de caminhada. Rev Bras Fisioter. 2010;14:24-30. [ Links ]

27. Cader AS, Vale RGS, Monteiro N, Pereira FF, Dantas EH. Comparação da Pimáx e da qualidade de vida entre idosas sedentárias, asiladas e praticantes de hidroginástica. Fit Perf J. 2006;5:101-8. [ Links ]

28. Laurin D, Verreault R, Lindsay J, MacPherson K, Rockwood K. Physical activity and risk of cognitive impairment and dementia in elderly persons. Arch Neurol. 2001;58:498-504. [ Links ]

29. Etgen T, Sander D, Huntgeburth U, Poppert H, Förstl H, Bickel H. Physical activity and incident cognitive impairment in elderly persons: The INVADE Study. Arch Intern Med. 2010;170:186-93. [ Links ]

30. Vercambre MN, Grodstein F, Manson JE, Stampfer MJ, Kang JH. Physical activity and cognition in women with vascular conditions. Arch Intern Med. 2011;171:1244-50. [ Links ]

31. Chan ED, Welsh CH. Geriatric Respiratory Medicine. Chest. 1998;114:1704-33. [ Links ]

32. Katzman WB, Wanek L, Shepherd JA, Sellmeyer DE. Age-related hyperkyphosis: its causes, consequences, and management. J Ortho. 2010;40(6):352-60. [ Links ]

Study conducted at Universidade Metodista de Piracicaba (UNIMEP) - Piracicaba (SP), Brazil.

Financing source: none

Approval at the Ethics Committee n. 70/10.

Received: November 2013; Accepted: October 2014

Correspondence to: Marlene Aparecida Moreno - Programa de Pós-Graduação em Fisioterapia - Rodovia do Açúcar, km 156 - CEP: 13400-901 - Piracicaba (SP), Brasil - E-mail: mamoreno@unimep.br

Conflict of interests: nothing to declare

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