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Lifetime physical activity and pelvic organ prolapse in middle-aged women

Published:February 03, 2014DOI:https://doi.org/10.1016/j.ajog.2014.01.035

      Objective

      To determine, in a case-control study, whether pelvic organ prolapse (POP) is associated with overall lifetime physical activity (combined leisure, outdoor, household, occupational), and lifetime leisure, lifetime strenuous, and teen years strenuous activity.

      Study Design

      One hundred ninety-one POP cases (defined as maximal vaginal descent ≥1 cm below the hymen) and 191 age and recruitment-site matched controls (defined as maximal vaginal descent ≤1 cm above the hymen) between 39-65 years with no or mild urinary incontinence, were recruited chiefly from primary care clinics. Participants completed Lifetime Physical Activity and Occupation Questionnaires, recalling activities during 4 age epochs. We performed separate logistic regression models for physical activity measures.

      Results

      Compared with controls, POP cases had greater body mass index and parity. Median overall lifetime activity, expressed in metabolic equivalents-hours/week, did not differ significantly between cases and controls. In adjusted analyses, we observed no associations between odds of POP and overall lifetime physical activity, lifetime leisure activity, or lifetime strenuous activity. There was a marginally significant nonlinear relationship between teen strenuous activity and POP with an increase in the log-odds of POP for women reporting ≥21 hours/week of strenuous activity (P = .046).

      Conclusion

      Lifetime physical activity does not increase the odds of anatomic POP in middle-aged women not seeking care for POP. Strenuous activity during teenage years may confer higher odds of POP. This relationship and the potential role of physical activity and POP incidence should be evaluated prospectively.

      Key words

      Physical activity is crucial in maintaining health, but high intensity activity increases risk for injury.
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      Physical activity-related injuries in walkers and runners in the aerobics center longitudinal study.
      Understanding how physical activity impacts pelvic organ prolapse (POP) is important: in their lifetimes, up to 1 in 5 women have surgery for POP.
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      Prevailing expert opinion holds that chronic repetitive straining, heavy lifting and high-impact activity can eventually produce changes in muscles, ligaments and connective tissue, leading to POP. To prevent POP, the American Urogynecologic Society recommends avoiding heavy lifting and repetitive strenuous activities.

      Take the floor. Voices for PFD. Washington, DC: American Urogynecologic Society, 2014. Available at: http://www.voicesforpfd.org/index.php?mo=cm&op=ld&fid=25. Accessed Oct. 22, 2013.

      Women with POP appear more likely to report strenuous jobs than women without.
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      Entstehungsursachen des deszensus (Factors promoting descensus, in German with English abstract).
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      Reproductive factors, family history, occupation and risk of urogenital prolapse.
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      Pelvic organ prolapse in the Women's Health Initiative: gravity and gravidity.
      However, limitations of published studies include not considering confounders, poorly defining occupational and activity histories, using nonstandardized POP outcomes, and excluding household activities, which represent a large portion of daily activity for many women. No study systematically assesses lifetime activity. Exploring the association between lifetime physical activity and POP cannot ethically be done in a randomized trial; a life-long cohort study, although possible, would be infeasible. Therefore, we conducted this case-control study to determine whether POP, defined by structured pelvic examination, is associated with (1) overall lifetime activity (leisure, outdoor, household, and occupational), (2) lifetime leisure activity, (3) lifetime strenuous activity, and (4) strenuous activity during the teen years. We analyzed strenuous activity during teen years as it is plausible that such activity, during this period of rapid changes in musculoskeletal structure, hormones, and weight, could influence pelvic floor integrity.

      Materials and Methods

      Institutional review boards of the University of Utah and Intermountain Healthcare approved this study. All participants completed an informed consent process. Detailed study methods have been published.
      • Nygaard I.
      • Shaw J.
      • Egger M.J.
      Exploring the association between lifetime physical activity and pelvic floor disorders: study and design challenges.
      Research nurses recruited women attending 1 of 17 primary care level gynecologic and family medicine clinics located across the Salt Lake Valley. Initially, we also recruited women from community advertising (flyers, brochures) but as relatively few women responded, relied primarily on in-person recruitment.
      Women were initially excluded if they were pregnant or within 6 months postpartum, <39 or >65 years, had prior surgical treatment for POP or incontinence, were not able to walk independently, had medical conditions associated with pelvic floor disorders or low physical activity (uncontrolled diabetes, neurologic disorders such as multiple sclerosis, spinal cord injury, or stroke, rheumatoid arthritis, radical hysterectomy or pelvic irradiation), had urgency-predominant incontinence, were currently undergoing treatment for cancer, or were unable to complete questionnaires. Underweight women (body mass index [BMI] <18.5 kg/m2) and women in obesity class III (BMI ≥40 kg/m2) were excluded as they are more likely to have functional and activity limitations. We chose the age range 39–65 years to reflect the population, included in the original validation of the physical activity instrument chosen for this study,
      • Chasan-Taber L.
      • Erickson J.B.
      • Nasca P.C.
      • Chasan-Taber S.
      • Freedson P.S.
      Validity and reproducibility of a physical activity questionnaire in women.
      which is likely to have developed POP and is still of an age likely to engage in a variety of physical activities. Trained research nurses performed the Pelvic Organ Prolapse Quantification (POP-Q), a reproducible method for assessing vaginal support.
      • Kobak W.H.
      • Rosenberger K.
      • Walters M.D.
      Interobserver variation in the assessment of pelvic organ prolapse.
      • Hall A.F.
      • Theofrastous J.P.
      • Cundiff G.W.
      • et al.
      Interobserver and intraobserver reliability of the proposed International Continence Society, Society of Gynecologic Surgeons, and American Urogynecologic Society pelvic organ prolapse classification system.
      • Bump R.C.
      • Mattiasson A.
      • Bo K.
      • et al.
      The standardization of terminology of female pelvic organ prolapse and pelvic floor dysfunction.
      We defined POP as present when any segment of the vagina descended at least 1 cm below the hymen (≥+1 cm) and absent when all vaginal segments were at least 1 cm above the hymen (≤−1 cm). We did not standardize the time of POP-Q examinations, as others found no differences in POP-Q values between examinations done in the morning or afternoon.
      • Pearce M.
      • Swift S.
      • Goodnight W.
      Pelvic organ prolapse: is there a difference in POPQ exam results based on time of day, morning or afternoon?.
      All participants voided immediately before the examination.
      To assess lifetime physical activity, we used the self-administered, reliable, and valid Lifetime Physical Activity Questionnaire (LPAQ) designed for use in women.
      • Chasan-Taber L.
      • Erickson J.B.
      • Nasca P.C.
      • Chasan-Taber S.
      • Freedson P.S.
      Validity and reproducibility of a physical activity questionnaire in women.
      • Chasan-Taber L.
      • Erickson J.B.
      • McBride J.W.
      • Nasca P.C.
      • Chasan-Taber S.
      • Freedson P.S.
      Reproducibility of a self-administered lifetime physical activity questionnaire among female college alumnae.
      The LPAQ assesses physical activity over 4 age periods, menarche to age 21, 22-34, 35-50, and 51-65 years, and includes leisure activity, outdoor work, and housework. The LPAQ is scored using metabolic equivalents (METs) obtained from the Compendium of Physical Activities
      • Ainsworth B.E.
      • Haskell W.L.
      • Whitt M.C.
      • et al.
      Compendium of physical activities: an update of activity codes and MET intensities.
      to calculate MET hours per week. METs provide a way to standardize absolute activity intensity that reflects multiples of the resting metabolic rate (Table 3 legend). Because the LPAQ does not query occupational activity, we added the Occupation Questionnaire (OQ), a component of the Lifetime Overall Physical Activity Questionnaire (LTPAQ).
      • Friedenreich C.M.
      • Courneya K.S.
      • Bryant H.E.
      The lifetime total physical activity questionnaire: development and reliability.
      We obtained overall lifetime physical activity by multiplying the MET score assigned to each activity by the reported number of hours per week, fraction of months in a year, and fraction of years lived in each age epoch, and added the average MET hours per week calculated on the Occupation Questionnaire. To calculate overall leisure physical activity, we restricted activities to those related to traditional exercise and recreation. Although there is much overlap between vigorous activities (defined as >6 METs
      American College of Sports Medicine
      ACSM's guidelines for exercise testing and prescription.
      ) and activities that result in higher force on the pelvic floor (which we term strenuous activity), some vigorous activities are not strenuous (like fast swimming) and some strenuous activities are not vigorous (like carrying a toddler for extended periods). We classified activities associated with relatively higher intraabdominal pressures or considered by pelvic floor experts to be potentially associated with the development or progression of POP
      • Nygaard I.
      • Shaw J.
      • Egger M.J.
      Exploring the association between lifetime physical activity and pelvic floor disorders: study and design challenges.
      as strenuous (Table 1) and reported average weighted strenuous hours per week.
      Table 1Activities classified as strenuous
      Activity
       Aerial dance trapeze
       Backpacking
       Bailing hay
       Basketball
       Carrying large pails of water or feed
       Carrying loads over 30 lb
       Cheerleading
       Chopping wood
       Cleaning large animal pens/farm work
       Climbing >10 flights of stairs per day
       European (team) handball
       Field hockey
       Football
       Hangliding/windsurfing
       Health club exercise, general
       Heavy carpentry
       Heavy garden work (shoveling, turning soil)
       Heavy housecleaning
       High jumping (track and field)
       Jet ski
       Jumping on trampoline
       Jumping rope
       Kickball
       Kickboxing
       Lacrosse
       Lifting >30 lb from floor
       Lifting >30 lb from counter height
       Lifting heavy weights (recreational/fitness)
       Lifting or carrying children or dependent elder
       Martial arts (all varieties)
       Motorcycle racing (motor cross)
       Moving heavy furniture without assistance
       Mowing lawn with push mower
       Other racquet sports
       Rock climbing
       Rugby
       Skiing, downhill; snowboarding
       Snow shoveling by hand
       Soccer
       Softball/baseball
       Springboard diving
       Sprinting
       Tennis
       Ultimate Frisbee
       Volleyball
       Wallyball
       Water skiing
      Nyaard. Pelvic organ prolapse and physical activity. Am J Obstet Gynecol 2014.
      We collected self-reported information about risk factors for pelvic floor disorders (Table 1). Because of the inaccuracy of recall of obstetric events, other than type of delivery, we did not ask more focused questions about childbirth history.
      • Elkadry E.
      • Kenton K.
      • White P.
      • Creech S.
      • Brubaker L.
      Do mothers remember key events during labor?.
      We used the validated Epidemiology of Prolapse and Incontinence Questionnaire (EPIQ) to collect pelvic floor symptoms.
      • Lukacz E.S.
      • Lawrence J.M.
      • Buckwalter J.G.
      • Burchette R.J.
      • Nager C.W.
      • Luber K.M.
      Epidemiology of prolapse and incontinence questionnaire: validation of a new epidemiologic survey.
      Participants completed questionnaires either on a paper or an electronic survey.
      • Egger M.J.
      • Lukacz E.S.
      • Newhouse M.
      • Wang J.
      • Nygaard I.
      Web versus paper-based completion of the epidemiology of prolapse and incontinence questionnaire.
      • Chan S.S.
      • Cheung R.Y.
      • Yiu A.K.
      • et al.
      Prevalence of levator ani muscle injury in Chinese women after first delivery.
      Exercise science graduate students reviewed missing and improbable responses on each LPAQ and OQ with participants using an established protocol. The LPAQ+OQ was considered insufficient for analysis if: (1) no physical activity was recorded of any type for an entire age epoch, (2) no physical activity over the entire LPAQ was recorded for leisure time or household domains, (3) overall physical activity was reported for more than 168 hours per week in any age epoch, or (4) calculated physical activity exceeded 671 MET hours/week in any age epoch.
      • Nygaard I.
      • Shaw J.
      • Egger M.J.
      Exploring the association between lifetime physical activity and pelvic floor disorders: study and design challenges.
      From the initial pool of participants, we then applied additional exclusion criteria. Because urinary incontinence and POP may coexist but have different risk factors, we excluded women with moderate/severe urinary incontinence defined as a score of ≥3 on the reliable, validated Incontinence Severity Index.
      • Sandvik H.
      • Seim A.
      • Vanvik A.
      • Hunskaar S.
      A severity index for epidemiological surveys of female urinary incontinence: comparison with 48-hour pad-weighing tests.
      • Sandvik H.
      • Espuna M.
      • Hunskaar S.
      Validity of the incontinence severity index: comparison with pad-weighing tests.
      Consistent with research by others, we excluded women with vaginal descent at the hymen to more clearly delineate POP vs no POP.
      • DeLancey J.O.
      • Morgan D.M.
      • Fenner D.E.
      • et al.
      Comparison of levator ani muscle defects and function in women with and without pelvic organ prolapse.
      • Woodman P.J.
      • Swift S.E.
      • O'Boyle A.L.
      • et al.
      Prevalence of severe pelvic organ prolapse in relation to job description and socioeconomic status: a multicenter cross-sectional study.
      Finally, we excluded those that did not return the activity questionnaires, or that returned them but their quality was insufficient for analysis.
      Research nurses obtaining outcome measures were masked to LPAQ + OQ results and exercise science researchers were masked to group assignment.
      The a priori calculated sample size, fully explained elsewhere,
      • Nygaard I.
      • Shaw J.
      • Egger M.J.
      Exploring the association between lifetime physical activity and pelvic floor disorders: study and design challenges.
      of at least 175 cases and 175 controls was calculated to provide over 80% power at the 2-sided 5% significance level to detect a protective odds ratio of 0.295 for a 1 SD increase in actual physical activity, accounting for measurement error.
      • Tosteson T.D.
      • Buzas J.S.
      • Demidenko E.
      • Karagas M.
      Power and sample size calculations for generalized regression models with covariate measurement error.

      Analysis

      We planned a priori to frequency match controls and cases for age, BMI, and recruitment source (primary care clinics vs community advertising). However, before beginning data analysis, we elected not to frequency match or adjust for BMI, as 2 prospective cohort studies published after our study began showed that lifetime physical activity ‘causes’ BMI.
      • Waller K.
      • Kaprio J.
      • Kujala U.M.
      Associations between long-term physical activity, waist circumference and weight gain: a 30-year longitudinal twin study.
      • Hankinson A.L.
      • Daviglus M.L.
      • Bouchard C.
      • et al.
      Maintaining a high physical activity level over 20 years and weight gain.
      Thus, BMI is on the direct pathway between lifetime activity and POP and is an effect of lifetime physical activity; adjusting could eliminate the association of activity with POP by overadjustment. We frequency matched controls to cases 1:1 by recruitment source and age (39-49, 50-60, 61-65 years), and selected controls using a computerized random number generator when >1 was eligible.
      We grouped physical activity variables into quintiles based on their distribution in the selected control group. In light of recent literature highlighting the independent deleterious effect of sedentary activity,
      • Wagner A.
      • Dallongeville J.
      • Haas B.
      • et al.
      Sedentary behaviour, physical activity and dietary patterns are independently associated with the metabolic syndrome.
      we assigned the 2nd quintile as the reference group. We performed logistic regression with variable selection guided by an updated directed acyclic graph (DAG), in which BMI was depicted as an intermediate variable, developed using DAGitty version 2.0.
      • Sung V.W.
      Reducing bias in pelvic floor disorders research: using directed acyclic graphs as an aid.
      • Textor J.
      • Hardt J.
      • Knuppel S.
      DAGitty: a graphical tool for analyzing causal diagrams.
      Required adjustment variables were education and the age match variable. Cough and constipation were also suggested, but the cell sizes for these were too small to include. We further adjusted for number of vaginal deliveries and hysterectomy status, based on past literature, which was permissible per the DAG. Regression diagnostics were checked for multicollinearity and influential observations. The primary physical activity measures were analyzed in separate models. Plots of initial regression coefficients were inspected, and the Stata multivariable fractional polynomials procedure was run to examine the functional relationship of physical activity variables with POP. Variables demonstrated a linear relationship on the logit scale, except for strenuous activity in the teen epoch, which had a cubic relationship.
      Missing values were addressed in the final models using multiple imputations in SAS 9.3 (SAS Institute, Cary, NC) with fully conditional specification, predictive mean matching of continuous variables, and logistic regression prediction of categorical variables.
      • van Buuren S.
      Multiple imputation of discrete and continuous data by fully conditional specification.
      • Donders A.R.
      • van der Heijden G.J.
      • Stijnen T.
      • Moons K.G.
      Review: a gentle introduction to imputation of missing values.
      • Brand J.
      Development, implementation and evaluation of multiple imputation strategies for the statistical analysis of incomplete data sets.
      • Yuan Y.
      Multiple imputation using SAS Software.
      As a sensitivity analysis, odds ratios were re-estimated using simulation-extrapolation (SIMEX),
      • Cook J.
      • Stefanski L.A.
      A simulation extrapolation method for parametric measurement error models.
      with bootstrapped standard errors to adjust for measurement error, using measurement error variances from our auxiliary reproducibility substudy, in which test-retest and intermethod (web vs paper administration) intraclass correlations were 0.64-0.88.

      Chung J, Shaw J, Nygaard I, Egger M. Test-retest reliability of paper and web versions of a lifetime physical activity questionnaire. Submitted. 2013.

      We used a 5% significance level for tests of effects, but considered P values for individual quintiles vs the reference category to be significant if < .01, to adjust for multiple comparisons. All statistical programming calculations were verified by a second independent research team member. Analysis was performed using SAS 9.3 (SAS Institute) and the multivariable fractional polynomial and simulation extrapolation procedures in Stata 11 and 12 (StataCorp, College Station, TX).

      Results

      We enrolled 1610 women; 1538 (95.5%) from primary care clinics and 72 (4.5%) from community advertising. After applying exclusion criteria demonstrated in Figure 1, there were 251 potential cases and 889 potential controls. Of these, 969/1140 (85%) returned the study questionnaires. There were no differences in age, BMI, race, ethnicity, or case/control status between those that did or did not return questionnaires. Of those that returned study questionnaires, LPAQ + OQ quality was sufficient for analysis in 864/969 (89.2%); there were no differences in these demographics between those with sufficient or insufficient questionnaire quality. All but 1 of the 192 potential cases could be matched 1:1 with a control. Participant characteristics are summarized in Table 2. The mean age (SD) of the population was 50.1 (7.1) years. There was a trend toward higher BMI in cases compared with controls (26.2 vs 25.2 kg/m2, respectively, P = .051). POP cases had greater parity (2.83 [SD 1.59] vs 1.84 [1.57] in controls, P < .0001,) and more vaginal deliveries (2.66 [1.6] vs 1.53 [1.58], P < .0001). Compared with women with 0 vaginal deliveries, those with 1, 2 and ≥3 had 3.50 (95% confidence interval [CI], 1.62–7.57), 5.64 (95% CI, 2.95–10.79), and 7.37 (95% CI, 4.02–13.53) times the odds of being POP cases. Other than the symptom of vaginal bulge, more common in the POP group (19.95% vs 4.2% in controls, P < .001), there were no differences in other pelvic floor symptoms between cases and controls, respectively, in urinary frequency (29.1% vs 26.7%, P = .60), urinary urgency (38.4% vs 30.0%, P = .08), urge urinary incontinence (23.7% vs 22.3%, P = .76), pelvic pain (12.0% vs 11.0%, P = .75), or fecal incontinence (20.4% vs 18.3%, P = .60).
      Figure thumbnail gr1
      Figure 1Participant flow
      The number of women screened and screen failures/declines refer to women recruited from the primary care source. These numbers are not available for women that responded to advertisements (community source); however, this recruitment technique was stopped early in the progress of the study.
      Nyaard. Pelvic organ prolapse and physical activity. Am J Obstet Gynecol 2014.
      Table 2Participant characteristics
      CharacteristicControlPOP caseP valueUnivariate OR (95% CI)
      Age (continuous), n, mean (SD)191, 50.74 (7.09)191, 51.31 (7.07)NANA
      Age (categorical), n (%)NANA
       39-5081 (42.41)
      Column percentage.
      81 (42.41)
       50-6188 (46.07)88 (46.07)
       61-6522 (11.52)22 (11.52)
      BMI (continuous, units = 5 for OR estimate), n, mean (SD)191, 25.23 (4.60)191, 26.17 (4.74).0511.243 (0.999–1.545)
      BMI (categorical), n (%).1288
       18.5-25112 (58.64)95 (49.74)Referent
       25-3049 (25.65)52 (27.23)1.251 (0.777–2.015)
       30-4030 (15.71)44 (23.04)1.729 (1.009–2.963)
      Parity (continuous), n190189< .00011.495 (1.299–1.722)
       Mean (SD)1.84 (1.57)2.83 (1.59)
       Median (range)2.00 (0.00–7.00)3.00 (0.00–8.00)
      Parity (categorical), n (%)< .0001
       Missing1 (0.52)2 (1.05)
       054 (28.27)15 (7.85)Referent
       123 (12.04)13 (6.81)2.035 (0.837–4.948)
       257 (29.84)58 (30.37)3.663 (1.858–7.222)
       3+56 (29.32)103 (53.93)6.621 (3.429–12.787)
      Number of vaginal deliveries, n190189< .00011.547 (1.346–1.779)
       Mean (SD)1.53 (1.58)2.66 (1.64)
       Median (range)1 (0–7)2 (0–8)
      Vaginal delivery (categorical), n (%)< .0001
       Missing1 (0.52)2 (1.05)
       076 (39.79)19 (9.95)Referent
       124 (12.57)21 (10.99)3.500 (1.618–7.573)
       239 (20.42)55 (28.80)5.641 (2.948–10.793)
       3+51 (26.70)94 (49.21)7.372 (4.016–13.533)
      Number of cesarean deliveries, n189189.04590.703 (0.497–0.994)
       Mean (SD)0.31 (0.77)0.17 (0.49)
       Median (range)0 (0–6)0 (0–3)
      Cesarean delivery (categorical), n (%).0628
       Missing2 (1.05)2 (1.05)
       0154 (80.63)163 (85.34)Referent
       117 (8.90)21 (10.99)1.167 (0.593–2.295)
       215 (7.85)3 (1.57)0.189 (0.054–0.666)
       3+3 (1.57)2 (1.05)0.630 (0.104–3.821)
      Hispanic, n (%).5873
       No183 (95.81)185 (96.86)Referent
       Yes8 (4.19)6 (3.14)0.742 (0.252–2.180)
      Race (OR and P value are based on nonwhite vs white), n (%).99090.995 (0.386–2.563)
       Missing1 (0.52)0 (0.00)
       American Indian0 (0.00)2 (1.05)
       Asian8 (4.19)6 (3.14)
       Black1 (0.52)1 (0.52)
       White181 (94.76)182 (95.29)
      Highest grade or year of school completed, n (%).0805
       Less than high school0 (0.00)1 (0.52)NA
       High school16 (8.38)20 (10.47)1.983 (0.935–4.205)
      Some college/associates48 (25.13)54 (28.27)1.700 (0.989–2.921)
       Bachelors59 (30.89)71 (37.17)1.818 (1.091–3.031)
       Graduate/professional degree68 (35.60)45 (23.56)Referent
      Current smoker, n (%).7784
       No184 (96.34)185 (96.86)Referent
       Yes7 (3.66)6 (3.14)0.853 (0.281–2.586)
      Hysterectomy, n (%).8841
       No163 (85.34)164 (85.86)Referent
       Yes28 (14.66)27 (14.14)0.958 (0.541–1.697)
      Postmenopausal, n (%).2189
       Missing2 (1.05)0 (0.00)
       No103 (53.93)87 (45.55)Referent
       Yes80 (41.88)97 (50.79)1.435 (0.952–2.166)
       Do not know6 (3.14)7 (3.66)1.381 (0.447–4.264)
      Hypertension, n (%).7655
       No164 (85.86)166 (86.91)
       Yes27 (14.14)25 (13.09)0.915 (0.510–1.642)
      Arthritis, n (%).7815
       No161 (84.29)159 (83.25)Referent
       Yes30 (15.71)32 (16.75)1.080 (0.627–1.861)
      Diabetes, n (%).4198
       No187 (97.91)189 (98.95)Referent
       Yes4 (2.09)2 (1.05)0.495 (0.090–2.734)
      Cancer, n (%).1097
       No182 (95.29)174 (91.10)Referent
       Yes9 (4.71)17 (8.90)1.976 (0.858–4.550)
      Cough, n (%).1383
       No186 (97.38)190 (99.48)Referent
       Yes5 (2.62)1 (0.52)0.196 (0.023–1.692)
      Heart attack or angina, n (%)NANA
       No190 (99.48)191 (100.00)
       Yes1 (0.52)0 (0.00)
      Major depression, n (%).4819
       No183 (95.81)180 (94.24)Referent
       Yes8 (4.19)11 (5.76)1.398 (0.550–3.556)
      Allergies, n (%).2729
       No125 (65.45)135 (70.68)Referent
       Yes66 (34.55)56 (29.32)0.786 (0.510–1.209)
      Sleep apnea, n (%).0418
       No188 (98.43)180 (92.24)
       Yes3 (1.57)11 (5.76)3.830 (1.051–13.952)
      Chronic constipation, n (%).6624
       No162 (84.82)165 (86.39)
       Yes29 (15.18)26 (13.61)0.880 (0.497–1.560)
      Number of prescription medications–other than vitamins and hormones (continuous), n189190.76011.016 (0.915–1.129)
       Mean (SD)1.5 (1.74)1.6 (2.10)
       Median (range)1 (0–9)1 (0–12)
      Self-reported health status, n (%).5401
       Excellent62 (32.46)56 (29.32)Referent
       Very good91 (47.64)97 (50.79)1.180 (0.744–1.871)
       Good37 (19.37)34 (17.80)1.017 (0.564–1.834)
       Fair1 (0.52)4 (2.09)4.428 (0.481–40.810)
      Recruitment type, n (%)NA
       Primary175(92.15)176 (92.15)NA
       Community15 (7.85)15 (7.85)NA
      BMI, body mass index; CI, confidence interval; NA, not applicable; OR, odds ratio; POP, pelvic organ prolapse.
      Nyaard. Pelvic organ prolapse and physical activity. Am J Obstet Gynecol 2014.
      a Column percentage.
      Summary measures for the primary physical activity variables by group are shown in Table 3. We observed no evidence that either lifetime overall, leisure or strenuous physical activity were associated with increased odds of POP in multivariable models (Table 4). However, strenuous physical activity in the teenage years exhibited a nonlinear (cubic polynomial) relationship with the log-odds of POP (P = .046) and was a risk factor for women reporting ≥21 hours/week of teen strenuous physical activity. Because this is a nonlinear relationship, the odds ratio is not constant and is illustrated in Figure 2.
      Table 3Physical activity summary measures in study population
      VariableControlPOP case
      Overall lifetime activity (average MET-hours/week), n
      All variables, with the exception of lifetime leisure activity, include leisure, household, outdoor, and occupation related activity
      191191
       Mean (SD)154.64 (85.64)154.67 (74.31)
       Median (IQR)146.38 (92.24–196.33)142.88 (104.23–190.69)
      Lifetime leisure activity (average MET-hours/week), n191191
       Mean (SD)38.77 (37.34)32.83 (33.90)
       Median (IQR)29.27 (13.35–49.70)22.34 (9.87–46.40)
      Lifetime strenuous activity (average hours/week), n191191
       Mean (SD)9.30 (6.19)10.56 (7.63)
       Median (IQR)7.77 (4.54–13.02)8.98 (5.13–14.04)
      Lifetime moderate activity (average hours/week), n
      Moderate activity: activities with 3-6 METs; vigorous activity: activities with >6 METs; based on ACSM's Guidelines for Exercise Testing and Prescription (8th ed).20
      191191
       Mean (SD)21.63 (16.06)23.01 (14.16)
       Median (IQR)16.97 (10.73–29.40)19.82 (12.41–29.96)
      Lifetime vigorous activity (average hours/week), n
      Moderate activity: activities with 3-6 METs; vigorous activity: activities with >6 METs; based on ACSM's Guidelines for Exercise Testing and Prescription (8th ed).20
      191191
       Mean (SD)2.30 (2.82)1.75 (2.07)
       Median (IQR)1.42 (0.52–3.10)1.05 (0.39–2.33)
      Strenuous activity (average hours/week) in 1st age epoch (12-21 years), n191191
       Mean (SD)5.08 (4.88)5.36 (6.21)
       Median (IQR)3.30 (1.29–7.54)3.18 (1.42–6.57)
      IQR, interquartile range; MET, metabolic equivalent; POP, pelvic organ prolapse.
      SD, standard deviation.
      Nyaard. Pelvic organ prolapse and physical activity. Am J Obstet Gynecol 2014.
      a All variables, with the exception of lifetime leisure activity, include leisure, household, outdoor, and occupation related activity
      b Moderate activity: activities with 3-6 METs; vigorous activity: activities with >6 METs; based on ACSM's Guidelines for Exercise Testing and Prescription (8th ed).
      American College of Sports Medicine
      ACSM's guidelines for exercise testing and prescription.
      Table 4Logistic regression analyses modeling the probability of POP by physical activity measure
      VariableAdjusted OR (95% CI)
      Adjusted for age and recruitment source
      Multivariable adjusted OR (95% CI)
      Adjusted for age, recruitment source, education, number of vaginal deliveries and hysterectomy
      PRIMARY PHYSICAL ACTIVITY VARIABLES
      Overall lifetime activity (quintiles)
       Quintiles
      1 vs 20.56 (0.29–1.07)0.61 (0.29–1.25)
      3 vs 20.77 (0.41–1.43)0.79 (0.39–1.57)
      4 vs 21.00 (0.54–1.84)0.92 (0.47–1.80)
      5 vs 20.73 (0.39–1.37)0.63 (0.31–1.26)
      Overall lifetime activity (continuous) (units = 70
      70 units is equivalent to an increase of 10 MET-hrs per day for each day of the week (for example, running at 10 minutes per mile pace for 1 extra hour per day or doing child care for 3.5 extra hours per day each day of the week)
      )
      1.00 (0.84–1.20)0.95 (0.78–1.16)
      Lifetime leisure activity (quintiles)
       1 vs 21.58 (0.85–2.93)1.36 (0.69–2.67)
       3 vs 21.21 (0.63–2.29)1.11 (0.55–2.23)
       4 vs 20.90 (0.46–1.77)0.83 (0.40–1.71)
       5 vs 20.89 (0.46–1.72)1.16 (0.56–2.43)
      Lifetime leisure activity (continuous) (units = 35
      35 units is equivalent to an increase of 5 MET-hours per day for each day of the week (for example, playing doubles tennis for one extra hour per day)
      )
      0.85 (0.69–1.04)0.97 (0.77–1.21)
      Lifetime strenuous activity (quintiles)
       1 vs 20.99 (0.51–1.93)1.19 (0.56–2.51)
       3 vs 21.18 (0.62–2.26)0.87 (0.43–1.79)
       4 vs 21.53 (0.82–2.88)1.01 (0.50–2.05)
       5 vs 21.21 (0.64–2.30)0.77 (0.38–1.58)
      Lifetime strenuous activity (continuous) (units = 7
      7 units is equivalent to an increase of 1 strenuous hour per day for each day of the week (for example, running at 10 minutes per mile pace for one extra hour per day)
      )
      1.21 (0.98–1.50)0.98 (0.78–1.24)
      Strenuous activity in teen epoch
      Menarche to age 21 years
      (quintiles)
       1 vs 20.85 (0.45–1.62)0.82 (0.40–1.65)
       3 vs 21.03 (0.55–1.92)0.98 (0.49–1.95)
       4 vs 20.98 (0.52–1.83)0.73 (0.37–1.47)
       5 vs 20.90 (0.48–1.70)0.77 (0.38–1.54)
      Strenuous activity in teen epoch (cubic polynomial) (units = 7)nonlinear relationship
      See Figure 2 odds ratios.
      SECONDARY PHYSICAL ACTIVITY VARIABLES
      Overall activity in teen epoch (quintiles)
       1 vs 20.84 (0.44–1.57)0.70 (0.35–1.40)
       3 vs 20.79 (0.42–1.49)0.70 (0.35–1.41)
       4 vs 20.91 (0.48–1.71)0.74 (0.37–1.50)
       5 vs 20.88 (0.47–1.65)0.70 (0.35–1.39)
      Overall activity in teen epoch (continuous) (units = 70
      70 units is equivalent to an increase of 10 MET-hrs per day for each day of the week (for example, running at 10 minutes per mile pace for 1 extra hour per day or doing child care for 3.5 extra hours per day each day of the week)
      )
      1.01 (0.80–1.26)1.01 (0.79–1.29)
      Overall activity between 21-35 years (quintiles)
       1 vs 20.56 (0.28–1.11)0.76 (0.36–1.61)
       3 vs 21.15 (0.62–2.14)1.01 (0.51–1.98)
       4 vs 20.84 (0.44–1.61)0.70 (0.34–1.43)
       5 vs 21.22 (0.65–2.28)0.79 (0.40–1.60)
      Overall activity between 21-35 years (continuous) (units = 70
      70 units is equivalent to an increase of 10 MET-hrs per day for each day of the week (for example, running at 10 minutes per mile pace for 1 extra hour per day or doing child care for 3.5 extra hours per day each day of the week)
      )
      1.14 (0.97–1.33)0.95 (0.79–1.15)
      Lifetime vigorous activity (quintiles)
       1 vs 21.26 (0.69–2.31)1.23 (0.63–2.40)
       3 vs 21.05 (0.56–1.95)1.00 (0.50–1.97)
       4 vs 20.67 (0.35–1.31)0.65 (0.31–1.35)
       5 vs 20.64 (0.33–1.24)0.67 (0.32–1.40)
      Lifetime vigorous activity (continuous) (units = 7
      7 units is equivalent to an increase of 1 strenuous hour per day for each day of the week (for example, running at 10 minutes per mile pace for one extra hour per day)
      )
      0.50 (0.27–0.95)0.59 (0.29–1.20)
      CI, confidence interval; MET, metabolic equivalent; OR, odds ratio; POP, pelvic organ prolapse.
      Nyaard. Pelvic organ prolapse and physical activity. Am J Obstet Gynecol 2014.
      a Adjusted for age and recruitment source
      b Adjusted for age, recruitment source, education, number of vaginal deliveries and hysterectomy
      c 70 units is equivalent to an increase of 10 MET-hrs per day for each day of the week (for example, running at 10 minutes per mile pace for 1 extra hour per day or doing child care for 3.5 extra hours per day each day of the week)
      d 35 units is equivalent to an increase of 5 MET-hours per day for each day of the week (for example, playing doubles tennis for one extra hour per day)
      e 7 units is equivalent to an increase of 1 strenuous hour per day for each day of the week (for example, running at 10 minutes per mile pace for one extra hour per day)
      f Menarche to age 21 years
      g See Figure 2 odds ratios.
      Figure thumbnail gr2
      Figure 2ORs for POP as a nonlinear function of hours/wk of strenuous activity in the teenage years: the effect of x hours/wk vs none
      The horizontal line marks an OR of 1.0: ORs below this are protective; and above this, indicate increased odds of POP.
      OR, odds ratio; POP, pelvic organ prolapse.
      Nyaard. Pelvic organ prolapse and physical activity. Am J Obstet Gynecol 2014.
      We noted no statistically significant differences in odds of POP associated with physical activity in age and recruitment site-adjusted analyses stratified by number of vaginal births (data not shown) All results were similar in sensitivity analyses adding BMI as a covariate to the fully adjusted models, as well as analyses restricted to women recruited only from primary care clinics. We repeated all analyses adjusting for measurement error using the SIMEX technique. No P value approached significance (additional data not shown) except teen strenuous activity (P = .055). In a nonsignificant trend, strenuous lifetime activity appeared protective against POP but the confidence interval was wide (odds ratio, 0.18 per additional 7 hours per week; 95% CI, 0.01–6.08).

      Comment

      In this population of relatively healthy middle-aged women, neither lifetime overall or strenuous activity increased the odds of POP. Only very high levels of teen strenuous activity increased the odds of POP, although lower levels appeared protective. The 7 women with the highest reported hours per week of teen strenuous activity (21-39 hours/week) were all POP cases. However, the sensitivity analysis adjusting for measurement error was marginally nonsignificant and very sensitive to changes in the coefficients of the cubic polynomial model. Thus we recommend future studies, which investigate teen strenuous activity and its relationship to vaginal support.
      The literature addressing the relationship between physical activity and POP is sparse. Similar to our study, no published report assessing exercise and POP supported an association.
      • Hendrix S.L.
      • Clark A.
      • Nygaard I.
      • Aragaki A.
      • Barnabei V.
      • McTiernan A.
      Pelvic organ prolapse in the Women's Health Initiative: gravity and gravidity.
      • Larsen W.I.
      • Yavorek T.A.
      Pelvic organ prolapse and urinary incontinence in nulliparous women at the United States Military Academy.
      • Braekken I.H.
      • Majida M.
      • Ellstrom Engh M.
      • Holme I.M.
      • Bo K.
      Pelvic floor function is independently associated with pelvic organ prolapse.
      • Miedel A.
      • Tegerstedt G.
      • Maehle-Schmidt M.
      • Nyren O.
      • Hammarstrom M.
      Nonobstetric risk factors for symptomatic pelvic organ prolapse.
      In contrast, 2 studies reported that heavy work increased the odds of POP surgery, but neither adjusted for parity.
      • Jorgensen S.
      • Hein H.O.
      • Gyntelberg F.
      Heavy lifting at work and risk of genital prolapse and herniated lumbar disc in assistant nurses.
      • Chiaffarino F.
      • Chatenoud L.
      • Dindelli M.
      • et al.
      Reproductive factors, family history, occupation and risk of urogenital prolapse.
      Heavy lifting increased the odds of bulge symptoms in one study, although 2 others reported no association between job classification and bulge symptoms or prolapse assessed using a nonvalidated measure.
      • Hendrix S.L.
      • Clark A.
      • Nygaard I.
      • Aragaki A.
      • Barnabei V.
      • McTiernan A.
      Pelvic organ prolapse in the Women's Health Initiative: gravity and gravidity.
      • Miedel A.
      • Tegerstedt G.
      • Maehle-Schmidt M.
      • Nyren O.
      • Hammarstrom M.
      Nonobstetric risk factors for symptomatic pelvic organ prolapse.
      • Slieker-ten Hove M.C.
      • Pool-Goudzwaard A.L.
      • Eijkemans M.J.
      • Steegers-Theunissen R.P.
      • Burger C.W.
      • Vierhout M.E.
      Symptomatic pelvic organ prolapse and possible risk factors in a general population.
      In 3 other studies, heavy work was associated with POP based on the POP-Q system, as was military paratrooper training.
      • Woodman P.J.
      • Swift S.E.
      • O'Boyle A.L.
      • et al.
      Prevalence of severe pelvic organ prolapse in relation to job description and socioeconomic status: a multicenter cross-sectional study.
      • Braekken I.H.
      • Majida M.
      • Ellstrom Engh M.
      • Holme I.M.
      • Bo K.
      Pelvic floor function is independently associated with pelvic organ prolapse.
      • Larsen W.I.
      • Yavorek T.
      Pelvic prolapse and urinary incontinence in nulliparous college women in relation to paratrooper training.
      Our study differs, in that we quantified lifetime physical activity inclusive of all domains. Rather than classifying jobs into categories, we collected data about each job to parse out whether a job considered strenuous, like “factory worker,” actually required operating heavy machines and lifting. To minimize differential misclassification, we studied women who were not seeking care for POP. Other than vaginal bulge, pelvic floor symptoms that might impact physical activity were similar between groups. Given that a minority of women with end-stage POP reported POP interfering substantially with physical activity,
      • Nygaard I.
      • Handa V.
      • Brubaker L.
      • et al.
      Physical activity in women planning sacrocolpopexy.
      it is unlikely that our cases with POP preferentially did less activity because of pelvic floor symptoms, which would have biased our results toward the null hypothesis.
      Strengths of our study include minimizing bias by recruiting participants not seeking care for POP and masking research nurses conducting POP assessment to physical activity or symptom status. We used a validated objective instrument to assess POP and a reliable lifetime physical activity instrument developed for women. We also conducted a nested reproducibility study within this population to enable sensitivity analyses adjusting for measurement error, and found few differences in the results.
      The primary limitation of our study is the cross-sectional nature of the data collection; therefore, we cannot establish causality. It is infeasible to directly measure activity prospectively over a lifetime and therefore, no lifetime physical activity questionnaire will ever be completely validated. However, the LPAQ has acceptable validity over the past 1 year compared with activity measured by accelerometry, and a similar interviewer who administered historical adulthood physical activity questionnaire demonstrated moderate correlations between the questionnaire and objectively measured activity collected 15 years earlier.
      • Chasan-Taber L.
      • Erickson J.B.
      • Nasca P.C.
      • Chasan-Taber S.
      • Freedson P.S.
      Validity and reproducibility of a physical activity questionnaire in women.
      • Besson H.
      • Harwood C.A.
      • Ekelund U.
      • et al.
      Validation of the historical adulthood physical activity questionnaire (HAPAQ) against objective measurements of physical activity.
      Retrospective, self-reported physical activity is commonly over reported.
      • Lissner L.
      • Potischman N.
      • Troiano R.
      • Bengtsson C.
      Recall of physical activity in the distant past: the 32-year follow-up of the prospective population study of women in Göteborg, Sweden.
      However, it is unlikely that our results were affected by differential misclassification; participants were not patients seeking care and were not told the study hypothesis or examination findings before questionnaire completion. Our results are most applicable to white, well-educated women with access to medical care. Further, these results may not apply to other populations or to women with both POP and stress urinary incontinence.
      Although we did not collect recalled BMI, another factor that increases intraabdominal pressure, by life epoch it is unlikely that obesity as a teen influenced our results because most of our participants were teens before the observed significant increases in adolescent obesity.
      • Troiano R.P.
      • Flegal K.M.
      • Kuczmarski R.J.
      • Campbell S.M.
      • Johnson C.L.
      Overweight prevalence and trends for children and adolescents. The National Health and Nutrition Examination Surveys, 1963 to 1991.
      Physical activity done just before the examination was not standardized, which may have affected POP-Q values,
      • Ali-Ross N.S.
      • Smith A.R.
      • Hosker G.
      The effect of physical activity on pelvic organ prolapse.
      but it is unlikely that different proportions of cases and controls performed recent activity.
      Although our study results challenge the conventional wisdom, they do not refute a large body of rigorous evidence. Rather, they provide rigorous evidence that lifetime physical activities, including strenuous activities done by women in the course of their lives, do not increase the odds of POP in middle-aged women, except possibly very high levels of strenuous activity performed in the teenage years. It is possible that isolated extreme events, difficult to detect by traditional physical activity questionnaires, may increase the risk of POP, especially in women predisposed based on delivery or genetic risk.
      • Lukacz E.S.
      • Lawrence J.M.
      • Contreras R.
      • Nager C.W.
      • Luber K.M.
      Parity, mode of delivery, and pelvic floor disorders.
      • Handa V.L.
      • Blomquist J.L.
      • Knoepp L.R.
      • et al.
      Pelvic floor disorders 5-10 years after vaginal or cesarean childbirth.
      • Lewicky-Gaupp C.
      • Margulies R.U.
      • Larson K.
      • Fenner D.E.
      • Morgan D.M.
      • DeLancey J.O.
      Self-perceived natural history of pelvic organ prolapse described by women presenting for treatment.
      Although a life-long prospective study is infeasible, studies targeting the shorter-term effects of physical activity on POP progression, recurrence, pelvic floor symptoms, and treatment-seeking in women with varying degrees of vaginal descent are feasible and important to undertake to fully understand the role physical activity plays.
      Based on our results, we recommend that adult women be physically active over their lifespan and not restrict activity to prevent POP. The teenage years, as well as early postpartum and postpelvic surgery are potentially vulnerable time points and women with early POP or high genetic risk are potentially vulnerable populations. Our results should not be used to counsel such women. Further research is needed to understand whether physical activity during these times and/or in these populations impacts future pelvic floor function and end-stage POP.

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