Swimming and Spinal Deformities: A Cross-Sectional Study Fabio Zaina, MD1, Sabrina Donzelli, MD1, Monia Lusini, MD1, Salvatore Minnella, MD1, and Stefano Negrini, Prof, MD2 Objective To compare the prevalence of spinal deformities and low back pain (LBP) in adolescent competitive swimmers and normal controls.
Study design This was a cross-sectional study with convenience sample of 112 adolescent competitive swimmers (62 females) compared with 217 students (106 females) of the same age (12.5 years). We designed a questionnaire to collect data on LBP and measured the angle of trunk rotation with a Bunnell scoliometer to screen for scoliosis, along with the plumbline distances for kyphosis and lordosis. Clinical cutoffs defined in the literature for detection of spinal deformities were applied. Analyses were performed using the t test and c2 test, and ORs and 95% CIs were calculated. Results Swimming was found to increase the risk of trunk asymmetries (OR, 1.86; 95% CI, 1.08-3.20). Swimming also increased the risk of hyperkyphosis (OR, 2.26; 95% CI, 1.35-3.77) and hyperlordosis (OR, 2.24; 95% CI, 1.064.73), and increased LBP in females by 2.1-fold (95% CI, 1.08-4.06). Conclusion Swimming is associated with an increased risk of trunk asymmetries and hyperkyphosis. Although swimming has been considered a complete sport and a treatment option for scoliosis, our data contradict that approach, and also show a higher prevalence of LBP in females. (J Pediatr 2014;-:---).
T
he relationship between sports and spinal disease, including both spinal deformities and back pain, has been widely discussed. The 2012 International Society on Scoliosis Orthopedic and Rehabilitation Treatment guidelines for the conservative treatment of scoliosis highlight the benefits of sport practice, but clearly state that sports cannot be considered a treatment.1 In contrast, for many years swimming has been considered a complete and comprehensive sport, and thus has been suggested and prescribed by many specialists as a specific treatment for vertebral deformities.2-5 This theory relies on the presumed relevance of gravitational force as an aggravating element for scoliosis.6 According to many authors, gravity plays a role in the development and progression of scoliosis.7 Even in ancient times, Hippocrates attempted hanging patients with scoliosis to counteract the negative effect of spinal load or to place the spine in traction using specific tools, the Hippocratic board and the Hippocratic ladder.8 Despite these theories, however, as far as we know no data have been published to support the efficacy of swimming as a specific scoliosis treatment. On the contrary, in the 1980s, some authors published data suggesting that swimming could be a risk factor for worsening scoliosis. Applying theories from previous studies,9 a thoracic hump of $10 mm can increase owing to mechanical stress in the thorax during swimming. Becker10 found a higher prevalence of functional scoliosis in athletes participating in the Junior Olympic Swimming Championship East in 1983. Only 1 study performed in subjects aged 8-12 years found no risk of trunk asymmetries associated with swimming, with the exception of an increased rate in hyperkyphosis in males. The level of physical activity considered was relatively low, starting from a minimum of 2 hours a week, and no details were given about the cutoff considered to define an asymmetry, or the measurement tools used.11 Regarding low back pain (LBP), some data suggest that some sports are associated with a higher prevalence, and a correlation has been found between weekly hours of sport participation and LBP,12 with moderate activity being protective but intense activity being harmful. There is conflicting published evidence regarding an association between swimming and LBP during adolescence. Masiero et al13 found a higher prevalence of LBP in swimmers, whereas Skoffer and Foldspang14 found swimming to be protective against LBP. Given the lack of clear and consistent evidence, we aimed to determine the prevalence of spinal deformities, including trunk asymmetries and hyperkyphosis, and LBP in adolescent competitive swimmers (ACS) compared with the general school population.
Methods This was a cross-sectional study using public school and private competitive swimming societies. We used a convenience sample in the region between Milan ACS ATR LBP
Adolescent competitive swimmers Angle of trunk rotation Low back pain
From the 1ISICO (Italian Scientific Spine Institute), Milan, Italy; and 2Physical and Rehabilitation Medicine, Department of Clinical and Experimental Sciences, University of Brescia, Brescia, Italy The authors declare no conflicts of interest. Portions of the study were presented at the International Society for the Study of the Lumbar Spine meeting, May 13-17, 2013, Scottsdale, AZ. 0022-3476/$ - see front matter. Copyright ª 2014 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.jpeds.2014.09.024
1
THE JOURNAL OF PEDIATRICS
and Varese, a densely populated area in northern Italy that can be considered representative of an urban population. The ACS group was recruited from several swimming societies, and controls were recruited from local schools. No restrictions were placed on sports practice in the latter group, because we wanted to compare competitive swimmers with the general population. We did not exclude subjects with previous diagnosis of scoliosis, because we wanted a very representative population. Because to our knowledge, no other study like this had been performed previously, we lacked data for calculating an appropriate sample size, and so instead, we attempted to recruit as many subjects as possible. Both groups were clinically evaluated by the same investigator to detect spinal deformities based on the angle of trunk rotation (ATR), measured using a Bunnell scoliometer at the thoracic, thoracolumbar, and lumbar levels, along with the plumbline distances at C7 and L3 to identify kyphosis and lordosis.15,16 The resulting data were analyzed for mean values and the use of a definite clinical cutoff. For Bunnell degrees, we set the cutoffs at 5 and 7 . These values are considered the most significant for screening, with 5 being a significant cutoff for subjects who could benefit from a specific exercise program and 7 a significant cutoff for patients requiring a brace.17-20 For the plumbline distances, we set different clinical cutoffs, 50 mm for C7 and 60 mm for L3, based on our normative data.16 We also considered the sagittal index, which consists of the sum of C7 and L3; a value >90 mm is considered to be correlated with increased kyphosis.16 To evaluate the prevalence of LBP, we administered a specific questionnaire that included questions about both present and past LBP and sciatica, use of drugs, need for medical visits, and eventual diagnostic examinations that had been validated previously.21 Analyses were performed using the t test and c2 test. ORs and 95% CIs were calculated. Alpha was set at 0.05.
Results A total of 329 adolescents out of 329 who were invited to participate were included and divided into 2 groups according to their sporting habits. The ACS group comprised 112 ACS (62 females, mean age 12.5 years; 50 males, mean age 12.5 years). These subjects trained at least 4 (up to 6) times a week for an average of 2-2.5 hours per session. The control group comprised 217 school pupils (106 females, mean age 12.5 years; 111 males, mean age 12.5 years). All subjects completed the clinical evaluation and the questionnaire. There were no missing data. The average ATR in males did not differ between the 2 groups (4.7 2.3 Bunnell for the ACS group vs 4.2 2.3 for controls); however, significant differences were found in females: (5.3 2.7 Bunnell vs 4.5 1.9 ; P < .05). Swimming was associated with an increased risk of trunk asymmetries (OR, 1.86; P < .05), with the highest risk in females (Table I). Females in the ACS group had a 2.5-fold higher risk than those in the control group. When 2
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Table I. Trunk asymmetry and scoliosis in the ACS group compared with the general population Variables
ATR threshold
Asymmetry
$5
Scoliosis threshold
$7
Population
OR
95% CI
Males Females Total Males Females Total
1.74 1.25 1.47 1.21 2.50* 1.86*
0.89-3.43 0.64-2.34 0.93-2.34 0.51-2.83 1.20-5.20 1.08-3.20
An ATR of 5 is considered significant for a curve of $20 ,19 whereas $7 is reportedly associated with a risk of scoliosis >25 .20 *P < .05.
considering the sagittal plane, swimming increased the risk of hyperkyphosis by 2.26-fold and the risk of lordosis by 2.24-fold in both sexes (Table II). With increasing degrees of sagittal plane clinical threshold, the size of the pathological population increased. Swimming also increased the risk of LBP, but only in females (OR, 2.10; Table III). For females, some evaluated situations were involved, including LBP prevalence, episodicity of pain, and health care resource utilization. In contrast, there was no negative influence on males (Tables III and IV).
Discussion Swimming might have a significant negative impact on the growing spine; trunk asymmetries increase, including those meaningful for scoliosis detection,17,18 as does kyphosis, which can be readily detected clinically.22 Moreover, we found an increased risk of LBP, but only in females. In this respect, there was a difference between the sexes, and swimming seems to have a greater impact on female adolescents. Keep in mind that in general, females are at greater risk for scoliosis1 and back pain.23 Swimming has traditionally been considered a safe and healthy sport for the spine,11 even in young children, and some clinicians have proposed it as a treatment for spinal
Table II. Sagittal plane clinical parameters in the ACS group compared with the general population Parameters Kyphosis C7 + L3 (sagittal index)
Plumbline distance Population
OR
95% CI
$90 mm
Males
C7
$50 mm
Females Total Males Females Total
2.33* 2.26* 2.83* 4.80* 3.54*
Lordosis L3
$60 mm
Males Females Total
2.03 0.64-6.37 2.35 0.87-6.33 2.24* 1.06-4.73
2.32* 1.13-4.76 1.12-4.86 1.35-3.77 1.07-7.45 1.60-14.52 1.73-7.24
A plumbline distance at C7 of 50 mm and/or a sagittal index of $90 mm is considered significant for hyperkyphosis; 60 mm at L3 is considered significant for hyperlordosis.22 *P < .05.
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ORIGINAL ARTICLES
Table III. Prevalence of LBP and clinical impact in female swimmers compared with the controls Variables LBP prevalence Males Females Total Chronic pain Males Females Total School absence Males Females Total Sport absence Males Females Total Medical evaluation Males Females Total Radiographic evaluation Males Females Total
OR
95% CI
1.19 2.10* 1.61*
0.61-2.35 1.08-4.06 1.01-2.57
0.78
0.07-8.77
5.64 1.05
0.61-52.42 0.28-3.84
0.96 2.70 1.74
0.31-2.86 0.96-7.62 0.79-3.38
5.33* 1.65
1.37-20.88 0.65-4.19
2
0.26-14.92 1.42-33.50
6.90*
*P < .05.
deformities.2-5 More recent investigators have raised doubts about the efficacy of swimming as a scoliosis treatment, reporting some negative effects of this sport. To our knowledge, only 2 previous studies have reported risks associated with competitive swimming. One was based on a previous theory and data9 about the negative effect of torsion of the thorax during swimming, which can increase a hump in cases where this is already marked. Becker10 collected data on the prevalence of scoliosis in young elite swimmers and found a higher rate than in the general population, but there was no real control group, and only generic epidemiologic data were used. Our findings support these previous studies by providing clinical data showing that in our population, compared with controls, swimmers had more spinal asymmetries due to the presence of a hump than controls. Unfortunately, we did not have the opportunity to perform radiographs to confirm the diagnosis of scoliosis, although the ATR measurement is a useful screening tool for identifying individuals with scoliosis and referring them for radiograph and expert evaluation. According to Bunnell, a good cutoff for screening is 7 , and the use of this value reduces the risk of rotational trunk asymmetries, which have no pathological meaning.17,19,20 A
Table IV. Frequency of LBP episodes in study females LBP episodes, % Group
Never
Once
Sometimes
Frequent
Persistent
Control ACS
47 31
16 19
36 42
1 5
0 3
Differences were tested using the c2 test (P < .05).
Swimming and Spinal Deformities: A Cross-Sectional Study
significant difference in the prevalence of ATR values in the ACS females confirmed the risks associated with this activity, because the probability of false-positive (rotational trunk asymmetries) should be the same in both groups. We found no differences between males in the 2 groups, likely owing to the lower prevalence of scoliosis in males and the fact that the pubertal spurt occurs slightly later than in females. In addition, as this was a cross-sectional study, we cannot be sure of the cause-and-effect relationship, but we must report this as an association. We also cannot rule out the possibility that some of the ACS group had started swimming after a diagnosis of scoliosis, with swimming being considered a treatment. However, swimming is a relatively popular sport in Italy, and many children swim, those with scoliosis and those without. Only those who have a special passion become competitive swimmers, and others attend the swimming pool in a less assiduous way. Thus, we consider it unlikely that girls affected by scoliosis self-selected to practice competitive swimming. The 2012 International Society on Scoliosis Orthopedic and Rehabilitation Treatment guidelines for the conservative treatment of scoliosis highlight the benefits of sports practice, but clearly state that sports cannot be considered a treatment for spinal deformities.1 Our data are consistent with the suggestions of the guidelines, and we strongly believe that sports can be very useful for children and adolescents, with specific benefits, both physical (eg, muscular strength, elasticity, balance, coordination, cardiovascular fitness) and educational. However, we also believe that using sport as a specific and modern treatment for scoliosis and suggesting that sport can itself cure spinal deformities is inappropriate, being in sharp contrast to our data and current guidelines.1 Some data already show that intensively mobilizing sports, such as rhythmic gymnastics, can enhance the progression of scoliosis.24 Another relevant finding of the present study is the higher prevalence of hyperkyphosis in the ACS males and females. A previous study reported contrasting data about kyphosis and swimming, with females showing a reduction in rate and males an increase.11 However, those data were collected in a younger population, making a comparison impossible, considering that the sagittal profile undergoes progressive development during adolescence, and that even a small difference in mean age can influence the results. A possible explanation for our findings is that muscles involved in the support of the spine are not trained to counteract gravity, so there can be some sort of postural collapse that progressively increases the sagittal curves of the spine. It would be unusual to find an increase in kyphosis together with signs of scoliosis, because the latter is usually characterized by reduced sagittal curves, but we checked for a possible association anyway, and failed to detect one. LBP also was quite frequent in our female subjects, consistent with previous literature documenting that 3
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females experience more back pain.23 Masiero et al13 identified swimming as a predictor of LBP in another Italian group of adolescents. This is apparently in contrast to the findings of Skoffer and Foldspang14 that swimming was protective for LBP. Our data are consistent with those of Masiero et al, with a relatively high prevalence of LBP in the females of the ACS group. Nevertheless, our data might not conflict with those of Skoffer and Foldspang, because in that study swimming was performed only twice a week, whereas our swimmers trained more frequently. This is a key point; competitive swimming, like many other competitive sports, exposes the individual to the risk of injuries and musculoskeletal diseases, whereas amateur sports are generally safe. In fact, the U-shaped correlation between sport and LBP has already been demonstrated; Auvinen et al25 reported an increased risk of LBP in adolescents who practiced sports for more than 6 hours per week and in girls who spent too much time sitting. In another study, the same group of authors reported that it was difficult to assess the contribution of each single sport as a risk factor for LBP, because many young persons practice multiple sports.26 Nevertheless, practicing different sports seemed to protect from the harmful effects of a single sport. Other authors reported more frequent disc degeneration in a young adult group of elite swimmers, although this event was not correlated with LBP,27 and the same data were found in a group of competitive fin swimmers.28 We attempted to perform a subgroup analysis to verify the effect of each single swimming style on LBP, but this was not possible because all of the subjects performed the crawl and some performed other strokes as well. The present study has some limitations. We did not perform a radiographic examination to confirm clinical findings, so it is theoretically possible that some of the spinal deformities in both groups are false-positives. Nevertheless, ATR is highly correlated with the Cobb angle and has been used as a screening tool,19 and the risk of false-positive results affects both groups. For LBP assessment, we used a validated questionnaire, with no clinical visits by subjects, meaning that we lacked some information. Recall bias might have influenced questionnaire responses, but we have no data to suggest that such bias differed between the ACS and control groups. Finally, as the study design was cross-sectional, we can only discuss correlations and not determine a real cause-and-effect relationship. Our findings in the present study are consistent with the literature, confirming that participation in competitive sports, particularly swimming, is associated with spinal injuries and back pain, losing the protective effect that the same activity can provide when practiced in a less-intense way. We do not intend to criticize swimming per se, but rather mean to inform clinicians and families about the drawbacks of this activity, and the connection between the extent of its practice and LBP and spinal deformities. We cannot treat scoliosis and hyperkyphosis through the practice 4
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of swimming only; the conservative treatments for these pathologies remain specific exercises29 and braces.30 n We thank Barbara Bonzanini and Barbara Colli for their assistance in collecting data. Submitted for publication Apr 29, 2014; last revision received Aug 14, 2014; accepted Sep 17, 2014. Reprint requests: Fabio Zaina, MD, ISICO, Via Bellarmino 13/1, 20141 Milan, Italy. E-mail: [email protected]
References 1. Negrini S, Aulisa AG, Aulisa L, Circo AB, de Mauroy JC, Durmala J, et al. 2011 SOSORT guidelines: orthopaedic and rehabilitation treatment of idiopathic scoliosis during growth. Scoliosis 2012;7:3. 2. Adams R. Games, sports, and exercises for the physically handicapped. 3rd ed. Philadelphia (PA): Lea & Febiger; 1982. 3. Blount W, Moe J. The Milwaukee brace. Baltimore (MD): Williams & Wilkins; 1978. 4. Kuprian W. Physical therapy for sports. Philadelphia (PA): Saunders; 1982. 5. Tachdijan M. Pediatric orthopedics. Philadelphia (PA): Saunders; 1972. 6. Burwell RG, Dangerfield PH, Freeman BJ. Etiologic theories of idiopathic scoliosis: somatic nervous system and the NOTOM escalator concept as one component in the pathogenesis of adolescent idiopathic scoliosis. Stud Health Technol Inform 2008;140:208-17. 7. Burwell RG, Aujla RK, Grevitt MP, Dangerfield PH, Moulton A, Randell TL, et al. Pathogenesis of adolescent idiopathic scoliosis in girls. A double neuro-osseous theory involving disharmony between two nervous systems, somatic and autonomic expressed in the spine and trunk: possible dependency on sympathetic nervous system and hormones, with implications for medical therapy. Scoliosis 2009;4:24. 8. Vasiliadis ES, Grivas TB, Kaspiris A. Historical overview of spinal deformities in ancient Greece. Scoliosis 2009;4:6. 9. Vercauteren M, Van Beneden M, Verplaetse R, Croene P, Uyttendaele D, Verdonk R. Trunk asymmetries in a Belgian school population. Spine 1982;7:555-62. 10. Becker TJ. Scoliosis in swimmers. Clin Sports Med 1986;5:149-58. 11. Boldori L, Da Solda M, Marelli A. Anomalies of the trunk: an analysis of their prevalence in young athletes. Minerva Pediatr 1999;51:259-64 (in Italian). 12. Sato T, Ito T, Hirano T, Morita O, Kikuchi R, Endo N, et al. Low back pain in childhood and adolescence: assessment of sports activities. Eur Spine J 2011;20:94-9. 13. Masiero S, Carraro E, Celia A, Sarto D, Ermani M. Prevalence of nonspecific low back pain in schoolchildren aged between 13 and 15 years. Acta Paediatr 2008;97:212-6. 14. Skoffer B, Foldspang A. Physical activity and low-back pain in schoolchildren. Eur Spine J 2008;17:373-9. 15. Zaina F, Atanasio S, Negrini S. Clinical evaluation of scoliosis during growth: description and reliability. Stud Health Technol Inform 2008;135:125-38. 16. Zaina F, Donzelli S, Lusini M, Negrini S. How to measure kyphosis in everyday clinical practice: a reliability study on different methods. Stud Health Technol Inform 2012;176:264-7. 17. Bunnell W. Outcome of spinal screening. Spine 1993;18:1572-80. 18. Grivas T, Wade M, Negrini S, O’Brien J, Maruyama T, Hawes M, et al. SOSORT consensus paper: school screening for scoliosis. Where are we today? Scoliosis 2007;26:17. 19. Bunnell W. An objective criterion for scoliosis screening. J Bone Joint Surg Am 1984;66:1381-7. 20. Samuelsson L, Noren L. Trunk rotation in scoliosis: the influence of curve type and direction in 150 children. Acta Orthop Scand 1997;68:273-6. 21. Negrini S, Carabalona R, Sibilla P. Backpack as a daily load for schoolchildren. Lancet 1999;354:1974. 22. Zaina F, Negrini S, Romano M, Aulisa AG. Repeatability of different methods to collect in everyday clinics the sagittal profile of patients with adolescent idiopathic scoliosis. Scoliosis 2007;2(Suppl 1):S44.
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- 2014 23. Calvo-Mu~ noz I, G omez-Conesa A, Sanchez-Meca J. Prevalence of low back pain in children and adolescents: a meta-analysis. BMC Pediatr 2013;13:14. 24. Tanchev PI, Dzherov AD, Parushev AD, Dikov DM, Todorov MB. Scoliosis in rhythmic gymnasts. Spine 2000;25:1367-72. 25. Auvinen J, Tammelin T, Taimela S, Zitting P, Karppinen J. Associations of physical activity and inactivity with low back pain in adolescents. Scand J Med Sci Sports 2008;18:188-94. 26. Auvinen JP, Tammelin TH, Taimela SP, Zitting PJ, Mutanen PO, Karppinen JI. Musculoskeletal pains in relation to different sport and exercise activities in youth. Med Sci Sports Exerc 2008;40:1890-900.
Swimming and Spinal Deformities: A Cross-Sectional Study
ORIGINAL ARTICLES 27. Kaneoka K, Shimizu K, Hangai M, Okuwaki T, Mamizuka N, Sakane M, et al. Lumbar intervertebral disk degeneration in elite competitive swimmers: a case-control study. Am J Sports Med 2007;35:1341-5. 28. Verni E, Prosperi L, Lucaccini C, Fedele L, Beluzzi R, Lubich T. Lumbar pain and fin swimming. J Sports Med Phys Fitness 1999;39:61-5. 29. Romano M, Minozzi S, Bettany-Saltikov J, Zaina F, Chockalingam N, Kotwicki T, et al. Exercises for adolescent idiopathic scoliosis. Cochrane Database Syst Rev 2012;CD007837. 30. Negrini S, Minozzi S, Bettany-Saltikov J, Zaina F, Chockalingam N, Grivas TB, et al. Braces for idiopathic scoliosis in adolescents. Cochrane Database Syst Rev 2010;CD006850.
5
Study design This was a cross-sectional study with convenience sample of 112 adolescent competitive swimmers (62 females) compared with 217 students (106 females) of the same age (12.5 years). We designed a questionnaire to collect data on LBP and measured the angle of trunk rotation with a Bunnell scoliometer to screen for scoliosis, along with the plumbline distances for kyphosis and lordosis. Clinical cutoffs defined in the literature for detection of spinal deformities were applied. Analyses were performed using the t test and c2 test, and ORs and 95% CIs were calculated. Results Swimming was found to increase the risk of trunk asymmetries (OR, 1.86; 95% CI, 1.08-3.20). Swimming also increased the risk of hyperkyphosis (OR, 2.26; 95% CI, 1.35-3.77) and hyperlordosis (OR, 2.24; 95% CI, 1.064.73), and increased LBP in females by 2.1-fold (95% CI, 1.08-4.06). Conclusion Swimming is associated with an increased risk of trunk asymmetries and hyperkyphosis. Although swimming has been considered a complete sport and a treatment option for scoliosis, our data contradict that approach, and also show a higher prevalence of LBP in females. (J Pediatr 2014;-:---).
T
he relationship between sports and spinal disease, including both spinal deformities and back pain, has been widely discussed. The 2012 International Society on Scoliosis Orthopedic and Rehabilitation Treatment guidelines for the conservative treatment of scoliosis highlight the benefits of sport practice, but clearly state that sports cannot be considered a treatment.1 In contrast, for many years swimming has been considered a complete and comprehensive sport, and thus has been suggested and prescribed by many specialists as a specific treatment for vertebral deformities.2-5 This theory relies on the presumed relevance of gravitational force as an aggravating element for scoliosis.6 According to many authors, gravity plays a role in the development and progression of scoliosis.7 Even in ancient times, Hippocrates attempted hanging patients with scoliosis to counteract the negative effect of spinal load or to place the spine in traction using specific tools, the Hippocratic board and the Hippocratic ladder.8 Despite these theories, however, as far as we know no data have been published to support the efficacy of swimming as a specific scoliosis treatment. On the contrary, in the 1980s, some authors published data suggesting that swimming could be a risk factor for worsening scoliosis. Applying theories from previous studies,9 a thoracic hump of $10 mm can increase owing to mechanical stress in the thorax during swimming. Becker10 found a higher prevalence of functional scoliosis in athletes participating in the Junior Olympic Swimming Championship East in 1983. Only 1 study performed in subjects aged 8-12 years found no risk of trunk asymmetries associated with swimming, with the exception of an increased rate in hyperkyphosis in males. The level of physical activity considered was relatively low, starting from a minimum of 2 hours a week, and no details were given about the cutoff considered to define an asymmetry, or the measurement tools used.11 Regarding low back pain (LBP), some data suggest that some sports are associated with a higher prevalence, and a correlation has been found between weekly hours of sport participation and LBP,12 with moderate activity being protective but intense activity being harmful. There is conflicting published evidence regarding an association between swimming and LBP during adolescence. Masiero et al13 found a higher prevalence of LBP in swimmers, whereas Skoffer and Foldspang14 found swimming to be protective against LBP. Given the lack of clear and consistent evidence, we aimed to determine the prevalence of spinal deformities, including trunk asymmetries and hyperkyphosis, and LBP in adolescent competitive swimmers (ACS) compared with the general school population.
Methods This was a cross-sectional study using public school and private competitive swimming societies. We used a convenience sample in the region between Milan ACS ATR LBP
Adolescent competitive swimmers Angle of trunk rotation Low back pain
From the 1ISICO (Italian Scientific Spine Institute), Milan, Italy; and 2Physical and Rehabilitation Medicine, Department of Clinical and Experimental Sciences, University of Brescia, Brescia, Italy The authors declare no conflicts of interest. Portions of the study were presented at the International Society for the Study of the Lumbar Spine meeting, May 13-17, 2013, Scottsdale, AZ. 0022-3476/$ - see front matter. Copyright ª 2014 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.jpeds.2014.09.024
1
THE JOURNAL OF PEDIATRICS
and Varese, a densely populated area in northern Italy that can be considered representative of an urban population. The ACS group was recruited from several swimming societies, and controls were recruited from local schools. No restrictions were placed on sports practice in the latter group, because we wanted to compare competitive swimmers with the general population. We did not exclude subjects with previous diagnosis of scoliosis, because we wanted a very representative population. Because to our knowledge, no other study like this had been performed previously, we lacked data for calculating an appropriate sample size, and so instead, we attempted to recruit as many subjects as possible. Both groups were clinically evaluated by the same investigator to detect spinal deformities based on the angle of trunk rotation (ATR), measured using a Bunnell scoliometer at the thoracic, thoracolumbar, and lumbar levels, along with the plumbline distances at C7 and L3 to identify kyphosis and lordosis.15,16 The resulting data were analyzed for mean values and the use of a definite clinical cutoff. For Bunnell degrees, we set the cutoffs at 5 and 7 . These values are considered the most significant for screening, with 5 being a significant cutoff for subjects who could benefit from a specific exercise program and 7 a significant cutoff for patients requiring a brace.17-20 For the plumbline distances, we set different clinical cutoffs, 50 mm for C7 and 60 mm for L3, based on our normative data.16 We also considered the sagittal index, which consists of the sum of C7 and L3; a value >90 mm is considered to be correlated with increased kyphosis.16 To evaluate the prevalence of LBP, we administered a specific questionnaire that included questions about both present and past LBP and sciatica, use of drugs, need for medical visits, and eventual diagnostic examinations that had been validated previously.21 Analyses were performed using the t test and c2 test. ORs and 95% CIs were calculated. Alpha was set at 0.05.
Results A total of 329 adolescents out of 329 who were invited to participate were included and divided into 2 groups according to their sporting habits. The ACS group comprised 112 ACS (62 females, mean age 12.5 years; 50 males, mean age 12.5 years). These subjects trained at least 4 (up to 6) times a week for an average of 2-2.5 hours per session. The control group comprised 217 school pupils (106 females, mean age 12.5 years; 111 males, mean age 12.5 years). All subjects completed the clinical evaluation and the questionnaire. There were no missing data. The average ATR in males did not differ between the 2 groups (4.7 2.3 Bunnell for the ACS group vs 4.2 2.3 for controls); however, significant differences were found in females: (5.3 2.7 Bunnell vs 4.5 1.9 ; P < .05). Swimming was associated with an increased risk of trunk asymmetries (OR, 1.86; P < .05), with the highest risk in females (Table I). Females in the ACS group had a 2.5-fold higher risk than those in the control group. When 2
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Table I. Trunk asymmetry and scoliosis in the ACS group compared with the general population Variables
ATR threshold
Asymmetry
$5
Scoliosis threshold
$7
Population
OR
95% CI
Males Females Total Males Females Total
1.74 1.25 1.47 1.21 2.50* 1.86*
0.89-3.43 0.64-2.34 0.93-2.34 0.51-2.83 1.20-5.20 1.08-3.20
An ATR of 5 is considered significant for a curve of $20 ,19 whereas $7 is reportedly associated with a risk of scoliosis >25 .20 *P < .05.
considering the sagittal plane, swimming increased the risk of hyperkyphosis by 2.26-fold and the risk of lordosis by 2.24-fold in both sexes (Table II). With increasing degrees of sagittal plane clinical threshold, the size of the pathological population increased. Swimming also increased the risk of LBP, but only in females (OR, 2.10; Table III). For females, some evaluated situations were involved, including LBP prevalence, episodicity of pain, and health care resource utilization. In contrast, there was no negative influence on males (Tables III and IV).
Discussion Swimming might have a significant negative impact on the growing spine; trunk asymmetries increase, including those meaningful for scoliosis detection,17,18 as does kyphosis, which can be readily detected clinically.22 Moreover, we found an increased risk of LBP, but only in females. In this respect, there was a difference between the sexes, and swimming seems to have a greater impact on female adolescents. Keep in mind that in general, females are at greater risk for scoliosis1 and back pain.23 Swimming has traditionally been considered a safe and healthy sport for the spine,11 even in young children, and some clinicians have proposed it as a treatment for spinal
Table II. Sagittal plane clinical parameters in the ACS group compared with the general population Parameters Kyphosis C7 + L3 (sagittal index)
Plumbline distance Population
OR
95% CI
$90 mm
Males
C7
$50 mm
Females Total Males Females Total
2.33* 2.26* 2.83* 4.80* 3.54*
Lordosis L3
$60 mm
Males Females Total
2.03 0.64-6.37 2.35 0.87-6.33 2.24* 1.06-4.73
2.32* 1.13-4.76 1.12-4.86 1.35-3.77 1.07-7.45 1.60-14.52 1.73-7.24
A plumbline distance at C7 of 50 mm and/or a sagittal index of $90 mm is considered significant for hyperkyphosis; 60 mm at L3 is considered significant for hyperlordosis.22 *P < .05.
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ORIGINAL ARTICLES
Table III. Prevalence of LBP and clinical impact in female swimmers compared with the controls Variables LBP prevalence Males Females Total Chronic pain Males Females Total School absence Males Females Total Sport absence Males Females Total Medical evaluation Males Females Total Radiographic evaluation Males Females Total
OR
95% CI
1.19 2.10* 1.61*
0.61-2.35 1.08-4.06 1.01-2.57
0.78
0.07-8.77
5.64 1.05
0.61-52.42 0.28-3.84
0.96 2.70 1.74
0.31-2.86 0.96-7.62 0.79-3.38
5.33* 1.65
1.37-20.88 0.65-4.19
2
0.26-14.92 1.42-33.50
6.90*
*P < .05.
deformities.2-5 More recent investigators have raised doubts about the efficacy of swimming as a scoliosis treatment, reporting some negative effects of this sport. To our knowledge, only 2 previous studies have reported risks associated with competitive swimming. One was based on a previous theory and data9 about the negative effect of torsion of the thorax during swimming, which can increase a hump in cases where this is already marked. Becker10 collected data on the prevalence of scoliosis in young elite swimmers and found a higher rate than in the general population, but there was no real control group, and only generic epidemiologic data were used. Our findings support these previous studies by providing clinical data showing that in our population, compared with controls, swimmers had more spinal asymmetries due to the presence of a hump than controls. Unfortunately, we did not have the opportunity to perform radiographs to confirm the diagnosis of scoliosis, although the ATR measurement is a useful screening tool for identifying individuals with scoliosis and referring them for radiograph and expert evaluation. According to Bunnell, a good cutoff for screening is 7 , and the use of this value reduces the risk of rotational trunk asymmetries, which have no pathological meaning.17,19,20 A
Table IV. Frequency of LBP episodes in study females LBP episodes, % Group
Never
Once
Sometimes
Frequent
Persistent
Control ACS
47 31
16 19
36 42
1 5
0 3
Differences were tested using the c2 test (P < .05).
Swimming and Spinal Deformities: A Cross-Sectional Study
significant difference in the prevalence of ATR values in the ACS females confirmed the risks associated with this activity, because the probability of false-positive (rotational trunk asymmetries) should be the same in both groups. We found no differences between males in the 2 groups, likely owing to the lower prevalence of scoliosis in males and the fact that the pubertal spurt occurs slightly later than in females. In addition, as this was a cross-sectional study, we cannot be sure of the cause-and-effect relationship, but we must report this as an association. We also cannot rule out the possibility that some of the ACS group had started swimming after a diagnosis of scoliosis, with swimming being considered a treatment. However, swimming is a relatively popular sport in Italy, and many children swim, those with scoliosis and those without. Only those who have a special passion become competitive swimmers, and others attend the swimming pool in a less assiduous way. Thus, we consider it unlikely that girls affected by scoliosis self-selected to practice competitive swimming. The 2012 International Society on Scoliosis Orthopedic and Rehabilitation Treatment guidelines for the conservative treatment of scoliosis highlight the benefits of sports practice, but clearly state that sports cannot be considered a treatment for spinal deformities.1 Our data are consistent with the suggestions of the guidelines, and we strongly believe that sports can be very useful for children and adolescents, with specific benefits, both physical (eg, muscular strength, elasticity, balance, coordination, cardiovascular fitness) and educational. However, we also believe that using sport as a specific and modern treatment for scoliosis and suggesting that sport can itself cure spinal deformities is inappropriate, being in sharp contrast to our data and current guidelines.1 Some data already show that intensively mobilizing sports, such as rhythmic gymnastics, can enhance the progression of scoliosis.24 Another relevant finding of the present study is the higher prevalence of hyperkyphosis in the ACS males and females. A previous study reported contrasting data about kyphosis and swimming, with females showing a reduction in rate and males an increase.11 However, those data were collected in a younger population, making a comparison impossible, considering that the sagittal profile undergoes progressive development during adolescence, and that even a small difference in mean age can influence the results. A possible explanation for our findings is that muscles involved in the support of the spine are not trained to counteract gravity, so there can be some sort of postural collapse that progressively increases the sagittal curves of the spine. It would be unusual to find an increase in kyphosis together with signs of scoliosis, because the latter is usually characterized by reduced sagittal curves, but we checked for a possible association anyway, and failed to detect one. LBP also was quite frequent in our female subjects, consistent with previous literature documenting that 3
THE JOURNAL OF PEDIATRICS
females experience more back pain.23 Masiero et al13 identified swimming as a predictor of LBP in another Italian group of adolescents. This is apparently in contrast to the findings of Skoffer and Foldspang14 that swimming was protective for LBP. Our data are consistent with those of Masiero et al, with a relatively high prevalence of LBP in the females of the ACS group. Nevertheless, our data might not conflict with those of Skoffer and Foldspang, because in that study swimming was performed only twice a week, whereas our swimmers trained more frequently. This is a key point; competitive swimming, like many other competitive sports, exposes the individual to the risk of injuries and musculoskeletal diseases, whereas amateur sports are generally safe. In fact, the U-shaped correlation between sport and LBP has already been demonstrated; Auvinen et al25 reported an increased risk of LBP in adolescents who practiced sports for more than 6 hours per week and in girls who spent too much time sitting. In another study, the same group of authors reported that it was difficult to assess the contribution of each single sport as a risk factor for LBP, because many young persons practice multiple sports.26 Nevertheless, practicing different sports seemed to protect from the harmful effects of a single sport. Other authors reported more frequent disc degeneration in a young adult group of elite swimmers, although this event was not correlated with LBP,27 and the same data were found in a group of competitive fin swimmers.28 We attempted to perform a subgroup analysis to verify the effect of each single swimming style on LBP, but this was not possible because all of the subjects performed the crawl and some performed other strokes as well. The present study has some limitations. We did not perform a radiographic examination to confirm clinical findings, so it is theoretically possible that some of the spinal deformities in both groups are false-positives. Nevertheless, ATR is highly correlated with the Cobb angle and has been used as a screening tool,19 and the risk of false-positive results affects both groups. For LBP assessment, we used a validated questionnaire, with no clinical visits by subjects, meaning that we lacked some information. Recall bias might have influenced questionnaire responses, but we have no data to suggest that such bias differed between the ACS and control groups. Finally, as the study design was cross-sectional, we can only discuss correlations and not determine a real cause-and-effect relationship. Our findings in the present study are consistent with the literature, confirming that participation in competitive sports, particularly swimming, is associated with spinal injuries and back pain, losing the protective effect that the same activity can provide when practiced in a less-intense way. We do not intend to criticize swimming per se, but rather mean to inform clinicians and families about the drawbacks of this activity, and the connection between the extent of its practice and LBP and spinal deformities. We cannot treat scoliosis and hyperkyphosis through the practice 4
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of swimming only; the conservative treatments for these pathologies remain specific exercises29 and braces.30 n We thank Barbara Bonzanini and Barbara Colli for their assistance in collecting data. Submitted for publication Apr 29, 2014; last revision received Aug 14, 2014; accepted Sep 17, 2014. Reprint requests: Fabio Zaina, MD, ISICO, Via Bellarmino 13/1, 20141 Milan, Italy. E-mail: [email protected]
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Swimming and Spinal Deformities: A Cross-Sectional Study
ORIGINAL ARTICLES 27. Kaneoka K, Shimizu K, Hangai M, Okuwaki T, Mamizuka N, Sakane M, et al. Lumbar intervertebral disk degeneration in elite competitive swimmers: a case-control study. Am J Sports Med 2007;35:1341-5. 28. Verni E, Prosperi L, Lucaccini C, Fedele L, Beluzzi R, Lubich T. Lumbar pain and fin swimming. J Sports Med Phys Fitness 1999;39:61-5. 29. Romano M, Minozzi S, Bettany-Saltikov J, Zaina F, Chockalingam N, Kotwicki T, et al. Exercises for adolescent idiopathic scoliosis. Cochrane Database Syst Rev 2012;CD007837. 30. Negrini S, Minozzi S, Bettany-Saltikov J, Zaina F, Chockalingam N, Grivas TB, et al. Braces for idiopathic scoliosis in adolescents. Cochrane Database Syst Rev 2010;CD006850.
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