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Factors affecting center of pressure in older adults: the Framingham Foot Study
© Hagedorn et al.; licensee BioMed Central Ltd. 2013
- Received: 30 January 2013
- Accepted: 3 May 2013
- Published: 8 May 2013
Although aberrant foot movement during gait has been associated with adverse outcomes in the lower extremities in clinical patients, few studies have analyzed population differences in foot function. The purpose of this study was to assess demographic differences in foot function in a large population-based study of community-dwelling adults.
Participants in this study were from the Framingham Foot Study. Walking data were collected from both feet using a Tekscan Matscan pressure mat. Foot function was characterized using the center of pressure excursion index (CPEI). T-tests were used to assess differences between population subsets based on sex, and in men and women separately, age, body mass index (BMI), physical activity and in women, past high heel use.
There were 2111 participants included in this analysis. Significant differences in CPEI were noted by sex (p< 0.0001), by age in women (p = 0.04), and by past high heel use in women (p = 0.04).
Foot function during gait was affected by sex, as well as by age and shoe-wear in women, but not by BMI or physical activity. Future work will evaluate possible relations between CPEI and outcomes such as falls, sarcopenia, and lower extremity function.
- Body Mass Index
- Hallux Valgus
- Plantar Pressure
- High Heel
- Lower Extremity Function
Foot function affects overall foot and lower extremity health. Prior research has linked abnormal foot function to adverse outcomes, such as lower extremity joint injuries [1, 2] and foot deformities . Although research has linked age [4, 5], weight [4, 6–8], shoe-wear  and body mass index (BMI) [7, 10–12], to differences in regional foot loading patterns, the effect of these variables on foot function in a community-dwelling sample of adults is unknown. Moreover, many of these studies have small sample sizes and highly selective inclusion and exclusion criteria, which minimize the generalizability of their results. The purpose of this study was to identify factors related to foot function in a population-based cohort of community-dwelling adults.
Data were obtained from the Framingham Foot Study , a population-based cohort of ambulatory adults residing in Framingham, Massachusetts, USA. The study population was drawn from two cohorts of the Framingham Heart Study. The Framingham Original Cohort was started in 1948 to investigate risk factors of Heart disease . Participants were selected through a two thirds sample of the town of Framingham, and have been examined biennially since. The Framingham Offspring Cohort is composed of adult children of the Original cohort members and their spouses who reside in or around Framingham. The Offspring cohort was started 1972 to investigate familial risk factors of heart disease, and participants have been examined every four years since . The Framingham Foot Study was approved by the Hebrew SeniorLife and Boston University Medical Center’s Institutional Review Boards. Participants provided written, informed consent prior to enrolment. We conducted cross-sectional analyses using the information collected in this cohort.
Between 2002 and 2008, Framingham Foot Study participants were seen for a data collection protocol that included a walking plantar pressure assessment, a validated foot examination, assessments of clinical variables (age, weight, height), and questionnaire-based assessments of activities and shoe-wear. Analysis inclusion criteria for this study required availability of foot function (center of pressure excursion index (CPEI)) data for at least one foot and valid data on age, BMI and physical activity (the Physical Activity Scale for the Elderly or PASE) . As the CPEI requires a heel-to-toe gait pattern, participants who did not have this gait pattern starting in the heel were excluded.
Plantar pressure data were collected from a Tekscan Matscan (Tekscan Inc, Boston) at 40 Hz. Participants walked at a self-selected pace and scans were collected using the two-step method (i.e., the foot strikes the mat on the second step) . One trial was collected for each foot. During testing, participants were allowed to practice walking across the mat. Scans were repeated in instances where participants struck the mat with the wrong foot, altered their gait to strike the mat, or failed the strike the mat with their whole foot.
Age groups were dichotomized as ≥ 65 years or < 65 years to provide information on older adults at a common population cut-point. BMI groups were dichotomized by obesity using the cut-off ≥ 30 kg/m2 or < 30 kg/m2. PASE scores were dichotomized at the sex-specific median, with the median being 134.5 for men and 115.5 for women.
Women were grouped into those who had always worn (all three age periods), sometimes (at least one, but not all age periods), and never worn high heels (referent). Sex-specific t-tests were used to compare CPEI distributions between age, BMI, and PASE groups. A t-test was used to compare CPEI between sexes. Linear regression was used to compare high heel groups using those who had never worn high heels as the referent, and to model the relation between CPEI and continuous age, BMI, and PASE measurements. To further examine the effect of age on CPEI, we categorized age as <55 years, 55–65 years, 65–75 years and 75+ years. Linear regression was used to compare CPEI among these age groups, using those <55 years of age as the referent. Alpha was set to 0.05.
Descriptive statistics (mean ± SD) for the participants in the Framingham Foot Study
Body mass index (BMI)
Physical activity scale for the elderly (PASE)
T-Tests for covariates associated with CPEI in the men and women of the Framingham Foot Study
Age < 65
Age < 65
Age ≥ 65
Age ≥ 65
BMI < 30
BMI < 30
BMI ≥ 30
BMI ≥ 30
Never wore High heeled shoes(ref)
Sometimes wore high heeled shoes
Always wore High heeled shoes
Mean center of pressure excursion index across age groups in the men and women of the Framingham Foot Study
18.53 ± 9.94
Age < 55
14.07 ± 10.39
17.04 ± 9.49
12.59 ± 9.81
16.73 ± 9.66
12.58 ± 10.06
15.94 ± 9.6
10.62 ± 9.78
The purpose of this study was to evaluate demographic factors associated with foot function in a community-dwelling, population-based large sample of men and women. We found significant differences in CPEI in groups stratified by age, sex, and past high heel use, but not by BMI or physical activity. Continuous models showed similar results in both men and women. These results indicate that future studies of foot function should consider the effects of sex, age, and history of high heel use as these factors may affect an outcome of interest.
Similar to prior studies [20, 21], this study found foot function differs by sex. This work noted that women displayed a lower CPEI. Smaller CPEI values are associated with greater amounts of pronation [18, 19]. This in part may be due to women having a more planus foot structure then men. Recent literature also suggests that arch height is reduced post-partum . As over-pronation has been clinically observed to be associated with several pedal pathologies (hallux valgus, hallux limitus, hallux rigidus, posterior tibial dysfunction, etc.) , this may mean women are at a greater risk of foot issues compared to men. The higher CPEI seen in men is consistent with prior work showing higher forces in the lateral metatarsals in men, which may correspond with a more supinated foot position . Thus, the current work extends the information available in the medical literature.
In this study, age older than 65 years was associated with lower CPEI in women, indicating more pronated foot function during gait. A similar magnitude of effect was noted in men, but was only significant in the continuous models. Clinicians have qualitatively observed that arches may become lower as persons age, and this observation is consistent with studies noting increased rates of flat feet  and pronated feet  with increasing age. If older individuals are becoming more planus they may be predisposed to a greater incidence of associated pathologies. As foot pathologies have been linked to functional limitations  and fall risk , this age related change might have significant consequences over time While there was no statistically significant difference in mean foot function between men ≥ 65 or < 65 years, both sexes had significantly lower CPEI among those 75 years or older, relative to those under 55, with a trend towards decrease over time in the other age groups. Future research should more thoroughly investigate biomechanical changes in the foot with age , as well as sex differences with age in foot function as perhaps it may help explain differences in rates of knee injury  and joint degeneration  between the sexes.
Individuals with higher BMI are suspected of having a higher prevalence of flat feet , which may be associated with increased foot pronation during the stance phase of gait . However, it is unclear whether static measures are accurate predictors of foot function [29–31], and few studies have directly assessed the relation between BMI and foot function. Previous research in small groups of adult volunteers has found that obese participants had larger plantar contact areas  and higher pressure under the forefoot during stance . Messier et al.  found obese participants had significantly greater rearfoot eversion relative to normal weight participants in a 2D motion capture analysis of female volunteers. In our current analysis, CPEI was unaffected by BMI, suggesting no relation between foot function and obesity. Several factors may account for the difference between this result and previous research. As CPEI measures foot function using the distribution of load under the foot over time , it may not be directly comparable to previous studies of static plantar pressure  and kinematics . Moreover, this study was population-based, while previous studies used small samples of volunteers [11, 32, 33]. Further, our study population was older (with an age range of 36 to 98 years versus samples primarily in their twenties  and forties ) and had a lower mean BMI (mean BMI was 28.4 kg/m2 versus 41.1 kg/m2 for obese group in the Messier study ).
Given the link between foot deformities and muscle weakness in diabetic patients  and fallers , and between foot deformities and altered foot biomechanics , physical activity may affect foot function. In the current study, however, CPEI was not affected by physical activity levels in either continuous or categorical analyses. While PASE does not measure physical function directly, it has been shown to be associated with a number of physiological measures of physical function . This result provides preliminary evidence that foot function as measured in the current study may not be significantly related to physical activity.
Both finite element modeling  and a study of young volunteers in Taiwan  found that high heels increased medial forefoot and toe loading in shod feet. However, the effects of habitually wearing high heels on barefoot gait are not well understood. In this study, women who always wore high heels over their adult lifespan had significantly lower CPEI than those who never wore them. Lower CPEI is consistent with the higher medial forefoot loading observed previously by these authors, and thus may indicate that changes from high heel use have a modifying effect on plantar loading. These results are in agreement with work in children showing that past shoe use can affect foot structure [9, 38]. Future research should look at the specific effects of past shoe-wear on plantar loading in both older women and men.
This study has several strengths and limitations worth noting. Because the study design was cross-sectional, causal relations between foot function and the factors under study cannot be inferred. Due to examination time constraints, only one plantar pressure scan per foot was obtained from each participant and thus, there is likely a larger degree of measurement error. This limitation is mitigated by the large sample size of the study, but if this error had an effect on the results, it would act to bias towards a null effect between variables rather than create a false positive . There were also several strengths to this population-based study. The study had a large sample size spanning a wide age range (36 to 98 years) and body size (BMI ranged 14.6 to 57 kg/m2), in addition to including both men and women.
This study showed that there are sex, age, and high heel use-related differences in foot function (as measured by CPEI) in a large population-based sample of men and women. These results should be helpful in informing future research and analysis of foot biomechanics. Future work will evaluate the relation between CPEI and outcomes such as falls, as well as lower extremity function, injury, musculoskeletal disorders, and disease.
Funding provided by NIH/NIAMS AR047853; Arthritis Foundation Postdoctoral Fellowship Award (Golightly) and the National Center for Research Resources and the National Center for Advancing Translational Sciences, National Institutes of Health, through Grant KL2TR000084 (Golightly). The content of this manuscript is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.
- Murphy DF, Connolly DA, Beynnon BD: Risk factors for lower extremity injury: a review of the literature. Br J Sports Med. 2003, 37: 13-29. 10.1136/bjsm.37.1.13.View ArticlePubMedPubMed CentralGoogle Scholar
- Ribeiro AP, Trombini-Souza F, Tessutti VD, Lima FR, João S, Sacco ICN: The effects of plantar fasciitis and pain on plantar pressure distribution of recreational runners. Clin Biomech. 2011, 26: 194-199. 10.1016/j.clinbiomech.2010.08.004.View ArticleGoogle Scholar
- Kernozek TW, Elfessi A, Sterriker S: Clinical and biomechanical risk factors of patients diagnosed with hallux valgus. J Am Podiatr Med Assoc. 2003, 93: 97-103.View ArticlePubMedGoogle Scholar
- Morag E, Cavanagh PR: Structural and functional predictors of regional peak pressures under the foot during walking. J Biomech. 1999, 32: 359-370. 10.1016/S0021-9290(98)00188-2.View ArticlePubMedGoogle Scholar
- Scott G, Menz HB, Newcombe L: Age-related differences in foot structure and function. Gait Posture. 2007, 26: 68-75. 10.1016/j.gaitpost.2006.07.009.View ArticlePubMedGoogle Scholar
- Menz HB, Morris ME: Clinical determinants of plantar forces and pressures during walking in older people. Gait Posture. 2006, 24: 229-236. 10.1016/j.gaitpost.2005.09.002.View ArticlePubMedGoogle Scholar
- Martinez-Nova A, Sanchez-Rodriguez R, Perez-Soriano P, Llana-Belloch S, Leal-Muro A, Pedrera-Zamorano JD: Plantar pressures determinants in mild Hallux Valgus. Gait Posture. 2010, 32: 425-427. 10.1016/j.gaitpost.2010.06.015.View ArticlePubMedGoogle Scholar
- Chiu MC, Wu HC, Chang LY, Wu MH: Center of pressure progression characteristics under the plantar region for elderly adults. Gait Posture. 2013, 37 (3): 408-412. 10.1016/j.gaitpost.2012.08.010.View ArticlePubMedGoogle Scholar
- Rao UB, Joseph B: The influence of footwear on the prevalence of flat foot. J bone joint surg. 1992, 74 (4): 525-527.Google Scholar
- Birtane M, Tuna H: The evaluation of plantar pressure distribution in obese and non-obese adults. Clin Biomech (Bristol, Avon). 2004, 19: 1055-1059. 10.1016/j.clinbiomech.2004.07.008.View ArticleGoogle Scholar
- Hills AP, Hennig EM, McDonald M, Bar-Or O: Plantar pressure differences between obese and non-obese adults: a biomechanical analysis. Int J Obes Relat Metab Disord. 2001, 25: 1674-1679. 10.1038/sj.ijo.0801785.View ArticlePubMedGoogle Scholar
- Phethean J, Nester C: The influence of body weight, body mass index and gender on plantar pressures: results of a cross-sectional study of healthy children's feet. Gait Posture. 2012, 36: 287-290. 10.1016/j.gaitpost.2012.03.012.View ArticlePubMedGoogle Scholar
- Dufour AB, Broe KE, Nguyen US, Gagnon DR, Hillstrom HJ, Walker AH, Kivell E, Hannan MT: Foot pain: is current or past shoewear a factor?. Arthritis Rheum. 2009, 61: 1352-1358. 10.1002/art.24733.View ArticlePubMedPubMed CentralGoogle Scholar
- Dawber TR, Meadors GF, Moore FE: Epidemiological Approaches to Heart Disease: The Framingham Study*. Am J Public Health Nations Health. 1951, 41: 279-286. 10.2105/AJPH.41.3.279.View ArticlePubMedPubMed CentralGoogle Scholar
- Feinleib M, Kannel WB, Garrison RJ, McNamara PM, Castelli WP: The Framingham offspring study. Design and preliminary data. Prev Med. 1975, 4: 518-525. 10.1016/0091-7435(75)90037-7.View ArticlePubMedGoogle Scholar
- Washburn RA, Smith KW, Jette AM, Janney CA: The Physical Activity Scale for the Elderly (PASE): development and evaluation. J Clin Epidemiol. 1993, 46: 153-162. 10.1016/0895-4356(93)90053-4.View ArticlePubMedGoogle Scholar
- McPoil TG, Cornwall MW, Dupuis L, Cornwell M: Variability of plantar pressure data. A comparison of the two-step and midgait methods. J Am Podiatr Med Assoc. 1999, 89: 495-501.View ArticlePubMedGoogle Scholar
- Song J, Hillstrom HJ, Secord D, Levitt J: Foot type biomechanics. comparison of planus and rectus foot types. J Am Podiatr Med Assoc. 1996, 86: 16-23.View ArticlePubMedGoogle Scholar
- Hillstrom HJ, Song J, Kraszewski AP, Hafer JF, Mootanah R, Dufour AB, Chow BS, Deland JT: Foot type biomechanics part 1: Structure and function of the asymptomatic foot. Gait Posture. 2012, 37 (3): 445-451.View ArticlePubMedPubMed CentralGoogle Scholar
- Murphy DF, Beynnon BD, Michelson JD, Vacek PM: Efficacy of plantar loading parameters during gait in terms of reliability, variability, effect of gender and relationship between contact area and plantar pressure. Foot Ankle Int. 2005, 26: 171-179.PubMedGoogle Scholar
- Putti A, Arnold G, Abboud R: Foot pressure differences in men and women. Foot Ankle Surg. 2010, 16: 21-24. 10.1016/j.fas.2009.03.005.View ArticlePubMedGoogle Scholar
- Segal NA, Boyer ER, Teran-Yengle P, Glass NA, Hillstrom HJ, Yack HJ: Pregnancy Leads to Lasting Changes in Foot Structure. Am J Phys Med Rehabil. 2013, 92: 232-240. 10.1097/PHM.0b013e31827443a9.View ArticlePubMedPubMed CentralGoogle Scholar
- Root ML, Orien WP, Weed JH: Clinical Biomechanics: Normal and Abnormal Function of the Foot, Vol 2. 1977, Los Angeles: Clinical Biomechanics Corp, 380-387.Google Scholar
- Shibuya N, Jupiter DC, Ciliberti LJ, VanBuren V, La Fontaine J: Characteristics of adult flatfoot in the United States. J Foot Ankle Surg. 2010, 49: 363-368. 10.1053/j.jfas.2010.04.001.View ArticlePubMedGoogle Scholar
- Leveille SG, Guralnik JM, Ferrucci L, Hirsch R, Simonsick E, Hochberg MC: Foot pain and disability in older women. Am J Epidemiol. 1998, 148: 657-665. 10.1093/aje/148.7.657.View ArticlePubMedGoogle Scholar
- Tinetti ME, Speechley M, Ginter SF: Risk factors for falls among elderly persons living in the community. N Engl J Med. 1988, 319 (26): 1701-1707. 10.1056/NEJM198812293192604.View ArticlePubMedGoogle Scholar
- Allen MK, Glasoe WM: Metrecom measurement of navicular drop in subjects with anterior cruciate ligament injury. J Athl Train. 2000, 35: 403-PubMedPubMed CentralGoogle Scholar
- Gross KD, Felson DT, Niu J, Hunter DJ, Guermazi A, Roemer FW, Dufour AB, Gensure RH, Hannan MT: Association of flat feet with knee pain and cartilage damage in older adults. Arthritis Care Res. 2011, 63: 937-944. 10.1002/acr.20431.View ArticleGoogle Scholar
- McPoil TG, Cornwall MW: The relationship between static lower extremity measurements and rearfoot motion during walking. J Orthop Sports Phys Ther. 1996, 24: 309-314.View ArticlePubMedGoogle Scholar
- Razeghi M, Batt ME: Foot type classification: a critical review of current methods. Gait Posture. 2002, 15: 282-291. 10.1016/S0966-6362(01)00151-5.View ArticlePubMedGoogle Scholar
- Hillstrom HJ, Mootanah R, Song J, Lenhoff MW, Hafer JF, Backus SI, Gagnon D, Deland JT: Foot Type Biomechanics Part 2: Are structure and anthropometrics related to function. Gait Posture. 2013, 37 (3): 452-456. 10.1016/j.gaitpost.2012.09.008.View ArticlePubMedGoogle Scholar
- Gravante G, Russo G, Pomara F, Ridola C: Comparison of ground reaction forces between obese and control young adults during quiet standing on a baropodometric platform. Clin Biomech (Bristol, Avon). 2003, 18: 780-782. 10.1016/S0268-0033(03)00123-2.View ArticleGoogle Scholar
- Messier SP, Davies AB, Moore DT, Davis SE, Pack RJ, Kazmar SC: Severe obesity: effects on foot mechanics during walking. Foot Ankle Int. 1994, 15: 29-34. 10.1177/107110079401500106.View ArticlePubMedGoogle Scholar
- van Schie CHM, Vermigli C, Carrington AL, Boulton A: Muscle weakness and foot deformities in diabetes. Diabetes Care. 2004, 27: 1668-1673. 10.2337/diacare.27.7.1668.View ArticlePubMedGoogle Scholar
- Mickle KJ, Munro BJ, Lord SR, Menz HB, Steele JR: ISB Clinical Biomechanics award 2009: toe weakness and deformity increase the risk of falls in older people. Clin Biomech. 2009, 24: 787-791. 10.1016/j.clinbiomech.2009.08.011.View ArticleGoogle Scholar
- Yu J, Cheung JT, Fan Y, Zhang Y, Leung AK, Zhang M: Development of a finite element model of female foot for high-heeled shoe design. Clin Biomech (Bristol, Avon). 2008, 23 (1): S31-S38.View ArticleGoogle Scholar
- Yung-Hui L, Wei-Hsien H: Effects of shoe inserts and heel height on foot pressure, impact force, and perceived comfort during walking. Appl Ergon. 2005, 36: 355-362. 10.1016/j.apergo.2004.11.001.View ArticlePubMedGoogle Scholar
- Sachithanandam V, Joseph B: The influence of footwear on the prevalence of flat foot. A survey of 1846 skeletally mature persons. J Bone Joint Surg Br. 1995, 77: 254-PubMedGoogle Scholar
- Blalock HM: Social Statistics. Revised. New York, NY: McGraw-Hill Box, GEP, & Cox, DR (1964) An analysis of transformations. J Royal Stat Soc, Series B (Methodology). 1979, 26: 211-252.Google Scholar
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