Association between body mass index, postural deviations, and self-reported musculoskeletal disorders in physically active adults

Associação do índice de massa corporal, alterações posturais e autorrelato de problema osteomioartiular em adultos ativos

Abstract

Abstract  Excess body weight contributes to biomechanical imbalance and musculoskeletal dysfunction, yet evidence on its association with postural deviations in physically active adults remains limited. This study examined the relationship between body mass index (BMI), self-reported musculoskeletal problems, and postural deviations by anatomical region in adults engaged in regular exercise. A cross-sectional study was conducted with 309 adults (207 females, 102 males) aged 20–59 years, training two to three times per week. Anthropometric data, BMI, musculoskeletal complaints, and postural characteristics were assessed. Posture was evaluated using the Portland State University (PSU) method via digital biophotogrammetry, generating a Postural Correction Index (PCI), with ≥80% indicating normal alignment. Statistical analyses were performed using JAVOMI software, with p ≤ 0.05 considered significant. Males presented higher BMI (26.7 ± 3.5 kg/m²; p < 0.005), classified as overweight. The most frequent musculoskeletal complaints were the spine (32.6%) and the knees (20.5%). PCI values were below reference in both sexes (females: 79.5%; males: 76.5%; p < 0.005). Common deviations included forward head posture (89.8%), thoracic scoliosis (100%), shoulder protrusion (68.8%), pelvic tilt (91.7%), and knee hyperextension (94.7%). Males also showed abdominal protrusion (43.1%) and lateral hip rotation (91.2%). Physically active males demonstrated higher BMI and postural deviations suggestive of increased mechanical load and risk for chronic musculoskeletal conditions. Both sexes exhibited clinically relevant postural imbalances, reinforcing the need to integrate BMI and posture evaluation into exercise prescription to optimize musculoskeletal health.

Key words:
Body mass index; Exercise; Obesity; Posture; Posturology

Resumo

Resumo  O objetivo desta pesquisa foi associar o índice de massa corporal (IMC), autorrelato de problema osteomioarticular e alterações posturais em adultos ativos. Participaram da amostra 309 adultos (207 feminino e 102 masculino), na faixa etária de 20 a 59 anos, que treinavam de duas a três vezes por semana, com duração entre 45 e 60 minutos. As variáveis coletadas foram massa corporal, estatura, autorrelato de problemas osteomioarticulares e postura corporal pelo método Portland State University, que adota como índice de correção postural (ICP) 80,0% e analisada pela biofotogrametria digital. Para análise estatística adotou-se o programa JAVOMI versão 2.5.6 e níveis de significância de p ≤ 0,05 e p ≤ 0,001, teste t de Welch e após o teste de homogeneidade de Levene não confirmar esse pressuposto. Constatou-se que o sexo masculino apresenta excesso de peso 26,7 (3,5) kg/m² (p < 0,005) e em ambos os sexos, representados por valor percentual (%), autorrelato de problemas osteomioarticulares, coluna vertebral 32,6 (1,7) e joelhos 20,5 (2,1), postura corporal estão abaixo dos padrões de referência: feminino ICP 79,5 (5,1) e masculino 76,5 (5,5) ambos mostrando significância estatística (p < 0,005) e nas alterações posturais observou-se: anteriorização da cabeça 89,8 (1,1); escoliose torácica 100,0 (0,0); protrusão de ombros 68,8 (1,2); inclinação de quadril 91,7 (2,5) e hiperextensão de joelhos 94,7 (2,4) e no sexo masculino protrusão abdominal 43,1 e rotação lateral de quadril 91,2. Conclui-se que o sexo masculino tem o risco de doenças crônico-degenerativas aumentado e em ambos os sexos se identificaram desequilíbrios osteomioarticulares considerados clínicos.

Palavras-chave:
Índice de massa corporal; Exercício; Obesidade; Postura; Posturologia

INTRODUCTION

As defined by the body mass index (BMI), overweight and obesity are well-established predictors of increased risk for noncommunicable diseases, including cardiovascular disorders, hypertension, diabetes, certain cancers, and cognitive decline. The global prevalence of excessive body weight continues to escalate, representing the largest modern public health epidemic. According to the World Obesity Atlas, an estimated 3.3 billion adults may be affected by 2035, compared to 2.2 billion in 2020, representing a proportional rise from 42% to over 54% of the adult population¹. Among individuals aged 5–19 years, projections indicate an increase from 22% (430 million) to 39% (770 million) within the same period¹. Excessive adiposity not only alters systemic metabolic homeostasis but also impacts the biomechanics of the musculoskeletal system, leading to postural compensations, increased mechanical overload, and joint misalignments²-⁹.

Poirier et al.⁹ highlighted that obesity induces structural and functional adaptations that compromise stability, particularly in the spine and lower limbs, varying depending on the duration of exposure and biological maturity. Aleixo et al.¹⁰ and Molina-Garcia et al.² demonstrated that overweight in children and adolescents promotes altered postural alignment, characterized by protrusion of the head and shoulders, lumbar hyperlordosis, pelvic anterior tilt, genu valgum, and flat feet. Siqueira and Silva⁶ observed that obese individuals exhibit lumbar instability and lordotic exaggeration associated with increased abdominal circumference. Similarly, Rezende et al.⁴ identified that overweight women presented spinal and scapular deviations accompanied by musculoskeletal pain and orthopedic complaints, while Silva et al.¹¹ reported that body fat distribution alters the body’s center of gravity and disrupts segmental alignment.

Although postural and biomechanical consequences of excess body weight have been widely examined in children and adolescents, there is still limited evidence regarding physically active adults. Therefore, the present study aimed to investigate the association between BMI, postural deviations by anatomical region, and self-reported musculoskeletal problems in adults regularly engaged in structured physical exercise.

METHOD

Study design and participants

This cross-sectional, descriptive–analytical study included 309 physically active adults aged 20–59 years (207 females, 102 males). All participants volunteered to take part in the study and were enrolled from local fitness facilities. Inclusion criteria included the regular participation in physical exercise two to three times per week, with session durations of 45–60 minutes, for a minimum period of one year. Exclusion criteria included a history of neuromuscular disorders, current musculoskeletal injuries, or recent surgeries.

Ethical considerations

The study complied with the principles of the Declaration of Helsinki and was approved by the Research Ethics Committee of São Judas Tadeu University (Protocol No. 684.186). All participants signed an informed consent form ensuring anonymity and data confidentiality, and granting permission for scientific dissemination.

Data collection

An individualized anamnesis form was used to collect demographic and clinical information, including sex, age, birthplace, duration of exercise practice, body mass (kg), height (m), and self-reported musculoskeletal symptoms (pain, discomfort, sprains, tendinopathies, muscle lesions, fractures, and surgical history). Data were recorded in Microsoft Excel 2019 for subsequent statistical processing.

Anthropometric evaluation

Body mass was measured using a digital scale with 0.1 kg precision, and height was assessed using a stadiometer accurate to 0.1 cm. BMI was calculated as body weight (kg) divided by height squared (m²), and participants were classified according to World Health Organization (2000) criteria as underweight (BMI < 18.5), normal weight (18.5–24.9), overweight (25.0–29.9), or obese (≥ 30.0)¹².

Postural assessment via digital biophotogrammetry

Posture was evaluated in the orthostatic position from four standardized views (anterior, right lateral, left lateral, and posterior). Participants stood barefoot; females wore shorts and sports bras, and males wore swim trunks or shorts. Long hair was tied back to facilitate cervical visualization.

Digital images were captured using a Lenovo Vibe K5 smartphone (13 MP camera), positioned 1.5 m from the participant and 1.0 m above the floor. Image analysis employed Corel Draw X7® (2016), a vector-based software enabling geometric segmentation and angular analysis of anatomical landmarks. The method followed the digital biophotogrammetry principles outlined by Santos¹³,¹⁴ and Miranda¹⁵ ensuring high reproducibility and metric accuracy.

Portland State University (PSU) method

The adapted PSU method (Portland State University) was used for visual and quantitative assessment of postural symmetry and asymmetry¹³,¹⁴,¹⁶-¹⁹. The Postural Correction Index (PCI) was calculated as the sum of segmental scores across dorsal and lateral views, divided by the total number of evaluated segments, multiplied by 100%. The following anatomical regions were analyzed: head and neck (RCP), thoracic and lumbar spine (RCDL), abdomen and pelvis (RAQ), and lower limbs (RMI). Each region was rated as:

1. 5 – no deviation;

2. 3 – mild lateral deviation;

3. 1 – marked lateral deviation.

A PCI ≥ 80% was considered indicative of adequate postural alignment¹³,¹⁴,¹⁶-¹⁸.

Statistical analysis

Descriptive statistics (mean, standard deviation, absolute and relative frequencies) were used for data analysis. For inferential analysis, Welch’s t-test was applied after Levene’s test indicated heterogeneity of variances. Statistical analyses were conducted using JAMOVI software (version 2.5.6), with significance levels set at p ≤ 0.05 and p ≤ 0.001.

RESULTS

No significant difference was observed between the sexes regarding age (Table 1). However, males showed significantly higher values for all anthropometric variables. The mean BMI for males classified this group as overweight, which may indicate a greater probability of developing chronic diseases and potential musculoskeletal complications.

Table 1
Welch’s t-test for mean differences between sexes in anthropometric characteristics among physically active adults aged 20–59 years.

Variables	Female (n = 207)	Male (n = 102)
Age (years)	37.2 (10.1)	37.4 (10.1) (ns)
Body mass (kg)	64.6 (12.6)	83.5* (12.3)
Height (m)a	1.63 (0.1)	1.77* (0.1)
BMI (kg/m2)	24.3 (4.4)	26.7* (3.5)

• Note. *BMI: Body Mass Index. p ≤ 0.001 (statistically significant difference). Significance levels: p < 0.05 and p < 0.001. Higher values for males. ªLevene’s test was significant (p < 0.05), suggesting violation of the homogeneity of variances for height. ns = no significant difference for age.

In both sexes, self-reported musculoskeletal problems were more frequent in the upper body, particularly in the spinal region (Table 2). In the lower body, the distribution of reports was more balanced between sexes, with knees being the most affected area in both groups.

Table 2
Self-reported musculoskeletal problems by anatomical region and sex (in %).

Anatomical region	Female	Male
Upper body
Head	1.9	1.0
Shoulders	5.8	11.8
Spine*	30.9	34.3
Lower body
Hips	5.8	3.9
Knees*	18.4	22.5
Ankles	6.3	9.8
Feet	4.3	2.0

• Note. *Most frequently reported anatomical region.

Both sexes exhibited PCI values below normal reference ranges, indicating postural deviations (Table 3). However, females presented better overall postural classification than males. When comparing regional indices (RCDL, RAQ, and RMI), females showed lower joint imbalances and greater anatomical symmetry. No significant differences were observed in the head and neck region (RCP) between sexes.

Table 3
Welch’s t-test for mean differences between sexes in postural assessment (in %).

Sex	RCP	RCDLa	RAQa	RMI	PCI
Female	77.9 (5.6)	86.5$ (7.7)	81.1# (11.5)	75.0$ (10.5)	79.5#* (5.1)
Male	78.0 (5.9)	81.3 (11.1)	77.8 (12.1)	70.2 (10.1)	76.5* (5.5)

• Note. *RCP = Head and neck region; RCDL = Thoracic and lumbar spine; RAQ = Abdomen and pelvis; RMI = Lower limbs; PCI = Postural Correction Index. Below normal reference values. #p ≤ 0.05; $p ≤ 0.001. Higher values observed in females. ªLevene’s test was significant (p < 0.05), suggesting heterogeneity of variances for RCDL and RAQ.

Both upper and lower body assessments revealed a higher prevalence of postural deviations in males (Table 4). Females demonstrated lower percentage values for most deviations, suggesting a lower probability of developing musculoskeletal disorders compared with males.

Table 4
Prevalence of postural deviations among physically active adults (in %).

Postural deviation	Female	Male
Upper body
Forward head posture*	88.4	91.2
Thoracic scoliosis*	100.0	100.0
Shoulder protrusion*	70.0	67.6
Hyperkyphosis	5.8	26.5
Abdominal protrusion	19.8	43.1*
Lower body
Pelvic tilt*	94.2	89.2
Hyperlordosis	17.9	13.7
Knee hyperextension*	92.3	97.1
Lateral hip rotation	38.2	91.2*
Flat feet	27.5	34.3

• Note. *Most prevalent postural deviation.

DISCUSSION

The primary contribution of this study lies in demonstrating the relationship between BMI, postural deviations, and self-reported musculoskeletal problems in physically active adults. Despite regular participation in exercise programs, both male and female participants presented postural misalignments below the expected normal range, suggesting that increased mechanical loading associated with excess weight may persist even among active populations.

The mean BMI of males (26.7 ± 3.5 kg/m²) classified them as overweight, corroborating epidemiological evidence linking higher BMI to mechanical overload and postural imbalance²⁰. This finding is clinically relevant, as excessive body mass alters the center of gravity, increases torque on weight-bearing joints, and predisposes individuals to pain and chronic musculoskeletal disorders. The spine and knees were the most frequently reported regions of musculoskeletal discomfort, in agreement with Rezende et al.⁴, who observed significant involvement of the lumbar spine and lower limbs in overweight populations. The prevalence of spinal deviations and lower limb misalignments found here reinforces the notion that postural integrity is highly sensitive to biomechanical stress and cumulative load.

Females demonstrated slightly better overall postural symmetry (PCI = 79.5 ± 5.1%) than males (76.5 ± 5.5%), possibly reflecting differences in fat distribution, exercise selection, and neuromuscular control. Deviations in the head and lower limbs were observed in both sexes, while the thoracic and pelvic regions were more stable among females. These findings are consistent with Santos et al.⁵ and Silva et al.¹¹, who emphasized the compensatory adaptations that occur along the kinetic chain in response to body mass distribution.

Forward head posture and thoracic scoliosis were nearly universal among participants (≥ 89%), consistent with previous studies attributing these conditions to prolonged sitting, repetitive asymmetrical movements, and excessive use of digital devices²¹,²². Sustained cervical protraction alters muscular balance, shortening the upper trapezius and semispinalis while weakening the deep neck flexors and scapular stabilizers. Pelvic tilt and knee hyperextension were also highly prevalent (>90%), underscoring the importance of the lumbopelvic complex in postural control. Pelvic asymmetries may reflect gluteal weakness, reduced trunk lateral stability, and hip abductor imbalance²². Knee hyperextension, by increasing posterior joint stress, may alter proprioceptive feedback and reduce dynamic stability²³.

Abdominal protrusion and lateral hip rotation, particularly common in males, may be explained by central fat accumulation and habitual standing with abducted feet, which increase anterior pelvic tilt and external femoral rotation²⁴. Such compensations contribute to spinal loading and altered gait mechanics. Foot posture plays a fundamental role in postural alignment. The observed prevalence of flat feet (27–34%) aligns, suggesting that decreased arch height contributes to altered plantar pressure distribution, posterior tibial tendon dysfunction, and eventual kinetic chain misalignment.

Taken together, these findings emphasize that even physically active adults are not immune to the cumulative biomechanical effects of body mass and habitual postures. Preventive strategies should include individualized corrective exercise programs targeting flexibility, postural re-education, and strengthening of stabilizing musculature to restore alignment and reduce pain symptoms.

CONCLUSION

The present study demonstrated that male adults exhibited higher BMI values, indicative of an overweight status, and consequently presented greater postural deviations and a higher risk for chronic musculoskeletal and metabolic diseases. In both sexes, the spinal and knee regions were the most frequently affected by self-reported musculoskeletal problems.

Postural assessment revealed that forward head posture, thoracic scoliosis, shoulder protrusion, pelvic tilt, and knee hyperextension were the most prevalent deviations, while abdominal protrusion and lateral hip rotation were markedly higher in males. These deviations, even in active individuals, highlight the persistent biomechanical effects of body weight and lifestyle habits on musculoskeletal integrity.

Integrating BMI assessment, postural analysis, and musculoskeletal evaluation provides a valuable framework for individualized exercise prescription. Corrective strategies focusing on postural re-alignment, neuromuscular stabilization, and weight management may enhance postural symmetry, reduce pain, and prevent chronic degenerative conditions linked to poor posture and mechanical overload.

• How to cite this article
  Santos JB, Figueira Junior A, Tourinho Filho H, Rezende RP, Fortes MSR, Gomes AC. Association between body mass index, postural deviations, and self-reported musculoskeletal disorders in physically active adults. Rev Bras Cineantropom Desempenho Hum 2026, 28:e110256. DOI: http://doi.org/10.1590/1980-0037.2026v28e110256
• COMPLIANCE WITH ETHICAL STANDARDS
• Funding
  This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. This study was funded by the authors.
• Ethical approval
  Ethical approval was obtained from the local Human Research Ethics Committee – Research Ethics Committee of São Judas Tadeu University and the protocol (Protocol No. 684.186). Was written in accordance with the standards set by the Declaration of Helsinki.

DATA AVAILABILITY STATEMENT

The data that support the findings of this study are available from the corresponding author upon reasonable request.

REFERENCES

• ¹ World Obesity Federation. World Obesity Atlas 2024 [Internet]. London: World Obesity Federation; 2024 [cited 2025 Dec 17]. Available from: https://data.worldobesity.org/publications/?cat=22
  » https://data.worldobesity.org/publications/?cat=22
• ² Molina-Garcia P, Miranda-Aparicio D, Ubago-Guisado E, Alvarez-Bueno C, Vanrenterghem J, Ortega FB. The impact of childhood obesity on joint alignment: a systematic review and meta-analysis. Phys Ther. 2021;101(7):pzab066. https://doi.org/10.1093/ptj/pzab066 PMid:33580953.
  » https://doi.org/10.1093/ptj/pzab066
• ³ Goi SB, Bianchi PA, Sturmer G, Nicolodi GV, Keller KD. Influência do peso corporal sobre o alinhamento postural de obesos. Biomotriz. 2018;12(3):49-57.
• ⁴ Rezende LS, Figueira LRPC, Morais ACBR, Hamú TCDS. Alterações posturais em indivíduos adultos eutróficos com sobrepeso e obesos e a presença de queixas álgicas musculoesqueléticas. In: III Congresso de Ensino, Pesquisa e Extensão da Universidade Estadual de Goiás, Inovação: inclusão social e direitos; 2016 Out 19-21; Pirenópolis, GO. Anais. Pirenópolis: Universidade Estadual de Goiás; 2016.
• ⁵ Santos ML, Martiniano SEG, Tavares RL. Avaliação de circunferência abdominal, razão cintura/quadril e IMC em adultos saudáveis. Rev Campo Saber. 2017;3(3):14.
• ⁶ Siqueira GR, Silva GAP. Alterações posturais da coluna e instabilidade lombar no indivíduo obeso: uma revisão de literatura. Fisioter Mov. 2011;24(3):557-66. https://doi.org/10.1590/S0103-51502011000300020
  » https://doi.org/10.1590/S0103-51502011000300020
• ⁷ Donnelly JE, Blair SN, Jakicic JM, Manore MM, Rankin JW, Smith BK, and the American College of Sports Medicine. Appropriate physical activity intervention strategies for weight loss and prevention of weight regain for adults. Med Sci Sports Exerc. 2009;41(2):459-71. https://doi.org/10.1249/MSS.0b013e3181949333 PMid:19127177.
  » https://doi.org/10.1249/MSS.0b013e3181949333
• ⁸ Wearing SC, Hennig EM, Byrne NM, Steele JR, Hills AP. Musculoskeletal disorders associated with obesity: a biomechanical perspective. Obes Rev. 2006;7(3):239-50. https://doi.org/10.1111/j.1467-789X.2006.00251.x PMid:16866972.
  » https://doi.org/10.1111/j.1467-789X.2006.00251.x
• ⁹ Poirier P, Giles TD, Bray GA, Hong Y, Stern JS, Pi-Sunyer FX, et al, and the American Heart Association, and the Obesity Committee of the Council on Nutrition, Physical Activity, and Metabolism. Obesity and cardiovascular disease: pathophysiology, evaluation, and effect of weight loss: an update of the 1997 American Heart Association scientific statement on obesity and heart disease from the Obesity Committee of the Council on Nutrition, Physical Activity, and Metabolism. Circulation. 2006;113(6):898-918. https://doi.org/10.1161/CIRCULATIONAHA.106.171016 PMid:16380542.
  » https://doi.org/10.1161/CIRCULATIONAHA.106.171016
• ¹⁰ Aleixo AA, Guimarães EL, Walsh IAP, Pereira K. Influência do sobrepeso e da obesidade na postura, na praxia global e no equilíbrio de escolares. J Hum Growth Dev. 2012;22(2):239-45. https://doi.org/10.7322/jhgd.44937
  » https://doi.org/10.7322/jhgd.44937
• ¹¹ Silva JF, Aragão MLL, Guerrieri M, Gonçalves M, Martins ABT, Madeira CM. A relação entre alterações posturais e gordura localizada: revisão de literatura. Rev Diálogos Acad. 2014;3(2):117-23.
• ¹² WHO: World Health Organization. Obesity: preventing and managing the global epidemic: report of a WHO consultation. Geneva: WHO; 2000. (WHO Technical Report Series; 894).
• ¹³ Santos JB. Posturologia. 1. ed. São Paulo: Ícone; 2025.
• ¹⁴ Santos JB. Manual de postura: avaliação e prescrição de exercícios preventivos, corretivos e compensatórios. 2. ed. São Paulo: Ícone; 2023.
• ¹⁵ Miranda GHL. Biofotogrametria para fisioterapeutas. 1. ed. São Paulo: Andreoli; 2014.
• ¹⁶ Althoff SA, Heyden SM, Robertson D. Back to the basics: whatever happened to posture? J Phys Educ Recreat Dance. 1988;59(7):20-4. https://doi.org/10.1080/07303084.1988.10606245
  » https://doi.org/10.1080/07303084.1988.10606245
• ¹⁷ Althoff SA, Heyden SM, Robertson D. Posture screening: a program that works. J Phys Educ Recreat Dance. 1988;59(8):26-32. https://doi.org/10.1080/07303084.1988.10606277
  » https://doi.org/10.1080/07303084.1988.10606277
• ¹⁸ Santos JB. Descrição do método de avaliação postural de Portland State University. Fisioter Bras. 2005;6(5):392-5. https://doi.org/10.33233/fb.v6i5.2029
  » https://doi.org/10.33233/fb.v6i5.2029
• ¹⁹ Santos JB, Figueira A Jr, Dubard M, Medeiros RMV, Rezende RP, Tourinho H Fo, et al. Anatomical profile and postural changes in young athletes practicing individual sports: what segments pattern? J Orthop Res Ther. 2025;10:1390.
• ²⁰ Cruz FCP, Duarte MMP, Silva JPS, Citon LM, Copriva ACAC. Índice de massa corporal elevado, exercício físico e postura: qual a relação? In: Anais do Congresso Brasileiro de Medicina de Família e Comunidade [Internet]; 2017 Nov 1; Curitiba. Anais eletrônicos. Curitiba: Galoá; 2017 [cited 2025 Dec 17]. p. 82124. Available from: https://proceedings.science/cbmfc/papers/indice-de-massa-corporal-elevado--exercicio-fisico-e-postura--qual-a-relacao-?lang=pt-br
  » https://proceedings.science/cbmfc/papers/indice-de-massa-corporal-elevado--exercicio-fisico-e-postura--qual-a-relacao-?lang=pt-br
• ²¹ Matos O. Avaliação postural e prescrição de exercícios corretivos. São Paulo: Phorte; 2010.
• ²² Kendall FP, McCreary EK, Provance PG, Rodgers MM, Romani WA. Músculos: provas e funções. 5. ed. São Paulo: Manole; 2007.
• ²³ Leal TS, Oliveira MP, Ribeiro MC, Moreira D. Avaliação dos graus de hiperextensão do joelho em praticantes de atividade física. Universitas Ciênc Saúde. 2011;9:19-34.
• ²⁴ Santos JBS, Toledo E, Castilho GAS, Bonaroti EP, Novelli C, Rezende RP, et al. Postura de praticantes de CrossFit. Rev Bras Fisiol Exerc. 2019;18(2):91-100. https://doi.org/10.33233/rbfe.v18i2.2895
  » https://doi.org/10.33233/rbfe.v18i2.2895

Edited by

• Scientific Editor:
  Diego Augusto Santos Silva

Publication Dates

• Publication in this collection
  29 May 2026
• Date of issue
  2026

History

• Received
  17 Dec 2025
• Accepted
  17 Mar 2026