Fecal incontinence patients categorized based on anal pressure and electromyography: Anal sphincter damage and clinical symptoms.

BACKGROUND: Disruption of external anal sphincter muscle (EAS) is an important factor in the multifactorial etiology of fecal incontinence (FI). OBJECTIVES: We categorize FI patients into four groups based on the location of lesion in neuromuscular circuitry of EAS to determine if there are differences with regards to fecal incontinence symptoms severity (FISI) score, age, BMI, obstetrical history, and anal sphincter muscle damage. METHODS: Female patients (151) without any neurological symptoms, who had undergone high-resolution manometry, anal sphincter EMG, and 3D ultrasound imaging of the anal sphincter were assessed. Patients were categorized into four groups: Group 1 (normal)-normal cough EMG (>10 µV), normal squeeze EMG (>10 µV), and normal anal squeeze pressure (>124 mmHg); Group 2 (cortical apraxia, i.e., poor cortical activation)-normal cough EMG, low squeeze EMG, and low anal squeeze pressure; Group 3 (muscle damage)-normal cough EMG, normal squeeze EMG, and low anal squeeze pressure; and Group 4 (pudendal nerve damage)-low cough EMG, low squeeze EMG, and low anal squeeze pressure. RESULTS: The four patient groups were not different with regards to the patient's age, BMI, parity, and FISI scores. 3D ultrasound images of the anal sphincter complex revealed significant damage to the internal anal sphincter, external anal sphincter, and puborectalis muscles in all four groups. CONCLUSION: The FI patients are a heterogeneous group; majority of these patients have significant damage to the muscles of the anal sphincter complex. Whether biofeedback therapy response is different among different patient groups requires study.

Pelvic Floor Mobility measured by Transperineal Ultrasound Imaging in Women with and without Urgency and Frequency Predominant Lower Urinary Tract Symptoms.

Background: Women with urgency/frequency predominant lower urinary tract symptoms (UF-LUTS) may have elevated pelvic floor muscle (PFM) position at rest and limited mobility with PFM contraction and bearing down, but this has not been quantified. Objectives: To compare PFM position and mobility using transperineal ultrasound (TPUS) at rest, maximal PFM contraction (perineal elevation), and bearing down (perineal descent) in women with and without UF-LUTS. We hypothesized that women with UF-LUTS would demonstrate elevated resting position and decreased excursion of pelvic landmarks during contraction and bearing down as compared to women without UF-LUTS. Study Design: Case-control study. Methods: Women with UF-LUTS were matched 1:1 on age, body mass index and vaginal parity to women without UF-LUTS. TPUS videos were obtained during 3 conditions: rest, PFM contraction, and bearing down. Levator plate angle (LPA) and puborectalis length (PR length), were measured for each condition. Paired t-tests or Wilcoxon signed rank tests compared LPA and PR length between cases and controls. Results: 21 case-control pairs (42 women): Women with UF-LUTS demonstrated greater LPA at rest (66.8 ± 13.2 degrees vs 54.9 ± 9.8 degrees; P=0.006), and less PR lengthening from rest to bearing down (0.2 ± 3.1 mm vs 2.1 ± 2.9 mm; P=.03). Conclusion: Women with UF-LUTS demonstrated more elevated (cranioventral) position of the PFM at rest and less PR muscle lengthening with bearing down. These findings highlight the importance of a comprehensive PFM examination and possible treatment for women with UF-LUTS to include PFM position and mobility.

Anorectal Anatomy and Function.

Anatomy of pelvic floor muscles has long been controversial. Novel imaging modalities, such as three-dimensional transperineal ultrasound imaging, MRI, and diffusion tensor imaging, have revealed unique myoarchitecture of the external anal sphincter and puborectalis muscle. High-resolution anal manometry, high-definition anal manometry, and functional luminal imaging probe are important new tools to assess anal sphincter and puborectalis muscle function. Increased understanding of the structure and function of anal sphincter complex/pelvic floor muscle has improved the ability to diagnose patients with pelvic floor disorders. New therapeutic modalities to treat anal/fecal incontinence and other pelvic floor disorders will emerge in the near future.

Do resistance exercises during biofeedback therapy enhance the anal sphincter and pelvic floor muscles in anal incontinence?

AIM: To determine if a biofeedback therapy that includes concentric resistance exercise for the anal sphincter muscles can improve muscle strength/function and improve AI symptoms compared to the traditional/non-resistance biofeedback therapy. BACKGROUND: Biofeedback therapy is the current gold standard treatment for patients with anal incontinence (AI). Lack of resistance exercise biofeedback programs is a limitation in current practice. METHODS: Thirty-three women with AI (mean age 60 years) were randomly assigned to concentric (resistance) or isometric (non-resistance) biofeedback training. Concentric training utilized the Functional Luminal Imaging Probe to provide progressive resistance exercises based on the patient's ability to collapse the anal canal lumen. Isometric training utilized a non-collapsible 10 mm diameter probe. Both groups performed a biofeedback protocol once per week in the clinic for 12 weeks and at home daily. High definition anal manometry was used to assess anal sphincter strength; symptoms were measured using FISI and UDI-6. 3D transperineal ultrasound imaging was used to assess the anal sphincter muscle integrity. RESULTS: Concentric and isometric groups improved FISI and UDI-6 scores to a similar degree. Both the concentric and isometric groups showed small improvement in the anal high-pressure zone; however, there was no difference between the two groups. Ultrasound image analysis revealed significant damage to the anal sphincter muscles in both patient groups. CONCLUSIONS: Concentric resistance biofeedback training did not improve the anal sphincter muscle function or AI symptoms beyond traditional biofeedback training. Anal sphincter muscle damage may be an important factor that limits the success of biofeedback training.

Hip and Pelvic Floor Muscle Strength in Women with and without Urgency and Frequency Predominant Lower Urinary Tract Symptoms.

BACKGROUND: Urgency and frequency are common lower urinary tract symptoms (UF-LUTS) in women. There is limited evidence to guide physical therapist-led treatment. OBJECTIVES: To compare hip and pelvic floor muscle strength between women with and without UF-LUTS. We hypothesized women with UF-LUTS would demonstrate 1) diminished hip external rotator and abductor strength and 2) equivalent pelvic floor strength and diminished endurance compared to controls. STUDY DESIGN: A matched case-control study. METHODS: Women with UF-LUTS (cases) and controls were matched on age, body mass index (BMI), vaginal parity. Examiner measured participants' 1) hip external rotator and abductor strength via dynamometry (maximum voluntary effort against fixed resistance) and 2) pelvic floor muscle strength (peak squeeze pressure) and endurance (squeeze pressure over a 10 second hold) via vaginal manometry. Values compared between cases and controls with paired-sample t-tests (hip) or Wilcoxon signed rank tests (pelvic floor). RESULTS: 21 pairs (42 women): Hip external rotation (67.0 ± 19.0 N vs 83.6 ± 21.5 N; P=0.005) and hip abduction strength (163.1 ± 48.1 N vs 190.1 ± 53.1 N; P=0.04) were significantly lower in cases than controls. There was no significant difference in pelvic floor strength (36.8 ± 19.9 cmH20 vs 41.8 ± 21.0 cmH20; P=0.40) or endurance (234.0 ± 149.6 cmH20*seconds vs 273.4 ± 149.1 cmH20*seconds; P=0.24). CONCLUSION: Women with UF-LUTS had weaker hip external rotator and abductor muscles, but similar pelvic floor strength and endurance compared to controls. Hip strength may be important to assess in patients with UF-LUTS, further research is needed.

Hip exercises improve intravaginal squeeze pressure in older women.

Objective: Pelvic Floor Muscle Training (PFMT), an accepted treatment for incontinence and pelvic floor dysfunction, has good evidence, though it is unknown if adjunct therapies can be useful. Strengthening the obturator internus (OI), along with other hip external rotator muscles, may help strengthen the pelvic floor muscles (PFM) through fascial attachment. We hypothesized that strengthening the hip external rotators will improve intravaginal squeeze pressure in older women.Methods: A total of 25 women (with or without pelvic floor dysfunction) greater than 55 years of age participated in monitored and home exercise sessions three times a week for 12 weeks. The exercises included concentric, isometric, and eccentric training of hip external rotators, without instruction to include PFM contraction. A physical therapist performed the assessments of each participant: Pelvic Floor Distress Inventory-20 (PFDI-20), a manual pelvic assessment, hip strength testing using a hand-held dynamometer and maximum intravaginal squeeze pressure using the PeritronTM PFM manometer (correct PFM contraction was confirmed visually and with palpation). Comparison was made to data obtained in a previous study in young women. Data were analyzed using paired t-tests and mixed model ANOVA.Results: Average intravaginal squeeze pressure increased from 21.47 ± 2.55 to 29.1 ± 3.15 cm H2O p < 0.0001. Hip external rotation strength increased in the right hip from 12.75 ± 0.46 to 15.42 ± 0.63 lbs p = 0.0009 and the left hip from 11.43 ± 0.43 to 15.61 ± 0.69 lbs p < 0.0001. The PFDI-20 scores decreased from 56.88 ± 10.76 to 40.62 ± 10.63, p > 0.05. Compared to a previous study in young women, both hip external rotation strength and intravaginal squeeze pressure increased with no significant difference between groups.Conclusion: Hip external rotation exercises may be effective as an indirect form of PFM exercise.

Loop analysis of the anal sphincter complex in fecal incontinent patients using functional luminal imaging probe.

Cardiac loops have been used extensively to study myocardial function. With changes in cardiac pump function, loops are shifted to the right or left. Functional luminal imaging probe (FLIP) recordings allow for loop analysis of the anal sphincter and puborectalis muscle (PRM) function. The goal was to characterize anal sphincter area-pressure/tension loop changes in fecal incontinence (FI) patients. Fourteen healthy subjects and 14 patients with FI were studied. A custom-designed FLIP was placed in the vagina and then in the anal canal, and deflated in 20-ml steps, from 90 to 30 ml. At each volume, subjects performed maximal voluntary squeezes. Area-pressure (AP) and area-tension (AT) loops were generated for each squeeze cycle. Three-dimensional ultrasound imaging of the anal sphincter and PRM were obtained to determine the relationship between anal sphincter muscle damage and loop movements. With the increase in bag volume, AP loops and AT loops shifted to the right and upward in normal subjects (both anal and vaginal). The shift to the right was greater, and the upward movement was less in FI patients. The difference in the location of AP loops and AT loops was statistically significant at volumes of 50 ml to 90 ml (P < 0.05). A similar pattern was found in the vaginal loops. There is a significant relationship between the damage to the anal sphincter and PRM, and loop location of FI patients. We propose AP and AT loops as novel ways to assess the anal sphincter and PRM function. Such loops can be generated by real-time measurement of pressure and area within the anal canal.NEW & NOTEWORTHY We describe the use of area-pressure (AP) and area-tension (AT)-loop analysis of the anal sphincters and puborectalis muscles in normal subjects and fecal incontinent patients using the functional luminal imaging probe (FLIP). There are differences in the magnitude of the displacement of the loops with increase in the FLIP bag volume between normal subjects and patients with fecal incontinence. The latter group shifts more to the right in AP and AT space.

Measuring length-tension function of the anal sphincters and puborectalis muscle using the functional luminal imaging probe.

The functional luminal imaging probe (FLIP) has been used to measure the distensibility of the anal canal. We hypothesized that with increasing distension of the anal canal with FLIP there will be an increase in length of the anal sphincter muscle allowing measurement of the length-tension function of anal sphincter and puborectalis muscles (PRM). We studied 14 healthy nulliparous women. A custom-designed FLIP bag (30-mm diameter) was placed in the vagina and then in the anal canal, distended in 10-ml steps with volumes ranging from 30 to 90 ml. At each volume, subject performed maximal voluntary squeezes. Length-tension measurements were also made with a manometric probe system. Tension was calculated (pressure × radius) in Newtons per meter using a custom software program. Peak tensions at different FLIP volumes were compared with the manometric data. No change in the luminal CSA was noted at low fluid volumes; the sphincter muscles were able to fully collapse the FLIP bag within the anal canal/vagina even at rest. At larger volumes, with each squeeze there was an increase in the bag pressure and reduction in the cross-sectional area, which represents concentric contraction of the muscle. Both rest and squeeze tension increased with the increase in volume in the anal as well as vaginal canal indicating that the external anal sphincter and puborectalis muscles produce more tension when lengthened. FLIP device, which has been used to describe the distensibility of the anal canal can also provide information on the length-tension function of the anal sphincters and PRM. NEW & NOTEWORTHY The functional luminal imaging probe (FLIP) has been used to describe the distensibility of the anal canal. This report is the first to describe the use of the FLIP in the vaginal canal and the anal canal to provide information on the length-tension function of the anal sphincter and puborectalis muscles, which may provide clinicians with additional information regarding the active components of muscle contraction involved in the anal closure function.

Early-Onset Physical Frailty in Adults With Diabesity and Peripheral Neuropathy.

OBJECTIVES: Diabesity (obesity and diabetes mellitus) has been identified as a potential contributor to early-onset frailty. Impairments contributing to early onset of physical frailty in this population are not well understood, and there is little evidence of the impact of peripheral neuropathy on frailty. The purpose of this study was to determine impairments that contribute to early-onset physical frailty in individuals with diabesity and peripheral neuropathy. METHODS: We studied 105 participants, 82 with diabesity and peripheral neuropathy (57 years of age, body mass index [BMI] 31 kg/m2); 13 with diabesity only (53 years of age, BMI 34 kg/m2) and 10 obese controls (67 years of age, BMI 32 kg/m2). Peripheral neuropathy was determined using Semmes Weinstein monofilaments; physical frailty was classified using the 9-item, modified Physical Performance Test; and knee extension and ankle plantarflexion peak torques were measured using isokinetic dynamometry. RESULTS: Participants with diabesity and peripheral neuropathy were 7.4 times more likely to be classified as physically frail. Impairments in lower-extremity function were associated with classification of frailty. CONCLUSIONS: Individuals with diabesity and peripheral neuropathy are particularly likely to be classified as frail. Earlier identification and interventions aimed at improving lower-extremity function may be important to mitigate the early-onset functional decline.

Differences in kinematics of the lumbar spine and lower extremities between people with and without low back pain during the down phase of a pick up task, an observational study.

BACKGROUND: Limited research exists on lumbar spine and lower extremity movement during functional tasks in people with and without low back pain (LBP). OBJECTIVE: To determine differences in lumbar spine and lower extremity kinematics in people with and without LBP during the down phase of a pick up task. DESIGN: Cross-sectional, observational study. METHOD: 35 people (14 M, 21 F, 26.9 ± 10.9 years, 24.8 ± 3.2 kg/m2); 18 with and 17 without LBP were matched based on age, gender and BMI. Kinematics of the lumbar spine and lower extremities were measured using 3D motion capture, while subjects picked up an object off the floor. People with LBP were examined and assigned to movement-based LBP subgroups. Repeated measures ANOVA tests were conducted to determine the effect of group and region on lumbar spine and lower extremity kinematics. A secondary analysis was conducted to examine the effect of LBP subgroup on lumbar spine kinematics. RESULTS: Compared to controls, subjects with LBP displayed greater upper and less lower lumbar flexion (P < 0.05), and more lumbar flexion during the first 25% of the pick up task (P < 0.01). There were no group differences in frontal or axial plane lumbar spine kinematics. Subjects with LBP displayed more frontal plane movement at the knee than control subjects (P < 0.01). There were no significant effects of movement-based LBP subgroup on kinematics (P > 0.05). CONCLUSIONS: When evaluating movement during a functional task, the clinician should consider regional differences in the lumbar spine, pattern of movement, and lower extremity movement.

Explanators of Sarcopenia in Individuals With Diabesity: A Cross-Sectional Analysis.

BACKGROUND AND PURPOSE: Excess lower extremity intermuscular adipose tissue (IMAT), reduced strength, and functional limitations are common in obese individuals with and without diabetes (the former termed diabesity). Individuals with diabesity are particularly susceptible to accelerated sarcopenia, which may be underdiagnosed. The purpose of this study was to determine critical values for leg IMAT volume, plantar flexor (PF) muscle strength, and physical performance that help identify individuals with diabesity who have sarcopenia. METHODS: Forty-three age- and sex-matched obese adults were studied: 12 with type 2 diabetes, 21 with diabetes and peripheral neuropathy, and 10 nondiabetic controls. Dual-energy x-ray absorptiometry-derived skeletal muscle index determined classification of sarcopenia. Leg fat (% IMAT), ankle (PF) peak torque, and power while ascending 10 steps, were used as explanators of sarcopenia. Receiver operating curves identified critical values for each explanator individually. Logistic regression models using all 3 explanators, and only PF torque and stair power, were also created. Receiver operating curve analyses identified the predicted probability that maximized each model's sensitivity and specificity. A leave-one-out cross validation was used to simulate the models' performance in an independent sample. RESULTS AND DISCUSSION: Thirty-two participants were sarcopenic, and 11 were not. Critical values for individual explanators were 21% IMAT, 68 Nm PF torque, and 441 watts of stair power. Predicted probabilities of .76 and .67 were chosen as the optimal cutoff probabilities for the model combining all 3 explanators, and the model combining PF torque and stair power, respectively. The cross-validation analysis produced an accuracy of 82.4%, using the cutoff probability of .5, and an accuracy of 76.5% using the cutoff of 0.76. The area under the curve for the cross validation receiver operating curve analysis was 0.82. Critical values of leg % IMAT, PF torque, and stair power can classify individuals with diabesity as sarcopenic. The results of the cross validation give us confidence that the sample used in this study was representative of the target population, and suggests models created from this sample may perform well in externally derived data sets. CONCLUSION: Clinicians may be able to use these critical values to select interventions that specifically target sarcopenia. Measures of % IMAT, PF torque, and stair power may offer a customized alternative to traditional sarcopenic classification systems, which may not be optimally suited to the common impairments among individuals with diabesity.

Impact of vaginal parity and aging on the architectural design of pelvic floor muscles.

BACKGROUND: Vaginal delivery and aging are key risk factors for pelvic floor muscle dysfunction, which is a critical component of pelvic floor disorders. However, alterations in the pelvic floor muscle intrinsic structure that lead to muscle dysfunction because of childbirth and aging remain elusive. OBJECTIVES: The purpose of this study was to determine the impact of vaginal deliveries and aging on human cadaveric pelvic floor muscle architecture, which is the strongest predictor of active muscle function. STUDY DESIGN: Coccygeus, iliococcygeus, and pubovisceralis were obtained from younger donors who were ≤51 years old, vaginally nulliparous (n = 5) and vaginally parous (n = 6) and older donors who were >51 years old, vaginally nulliparous (n = 6) and vaginally parous (n = 6), all of whom had no history of pelvic floor disorders. Architectural parameters, which are predictive of muscle's excursion and force-generating capacity, were determined with the use of validated methods. Intramuscular collagen content was quantified by hydroxyproline assay. Main effects of parity and aging and the interactions were determined with the use of 2-way analysis of variance, with Tukey's post-hoc testing and a significance level of .05. RESULTS: The mean age of younger and older donors differed by approximately 40 years (P = .001) but was similar between nulliparous and parous donors within each age group (P > .9). The median parity was 2 (range, 1-3) in younger and older vaginally parous groups (P = .7). The main impact of parity was increased fiber length in the more proximal coccygeus (P = .03) and iliococcygeus (P = .04). Aging changes manifested as decreased physiologic cross-sectional area across all pelvic floor muscles (P < .05), which substantially exceeded the age-related decline in muscle mass. The physiologic cross-sectional area was lower in younger vaginally parous, compared with younger vaginally nulliparous, pelvic floor muscles; however, the differences did not reach statistical significance. Pelvic floor muscle collagen content was not altered by parity but increased dramatically with aging (P < .05). CONCLUSIONS: Increased fiber length in more proximal pelvic floor muscles likely represents an adaptive response to the chronically increased load placed on these muscles by the displaced apical structures, presumably as a consequence of vaginal delivery. In younger specimens, a consistent trend towards decrease in force-generating capacity of all pelvic floor muscles in the parous group suggests a potential mechanism for clinically identified pelvic floor muscle weakness in vaginally parous women. The substantial decrease in predicted muscle force production and fibrosis with aging represent likely mechanisms for the pelvic floor muscle dysfunction in older women.

Adipose tissue content, muscle performance and physical function in obese adults with type 2 diabetes mellitus and peripheral neuropathy.

AIMS: To determine leg intermuscular (IMAT) and subcutaneous (SQAT) adipose tissue and their relationships with muscle performance and function in obese adults with and without type 2 diabetes and peripheral neuropathy (T2DMPN). METHODS: Seventy-nine age-matched obese adults were studied, 13 T2DM, 54 T2DMPN, and 24 obese controls. Leg fat (%IMAT, %SQAT) volumes were quantified using MRI. Ankle plantar flexion (PF) torque and power were assessed with isokinetic dynamometry. Physical function was assessed with 9-item Physical Performance Test (PPT), 6-minute walk distance, single-limb balance, and time to ascend 10 stairs. One-way ANOVAs determined group differences, and multiple regression predicted PPT score from disease status, % IMAT, and PF power. RESULTS: T2DMPN participants had 37% greater IMAT volumes and 15% lower SQAT volumes than controls (p =. 01). T2DMPN and T2DM showed reduced PF torque and power compared to controls. T2DMPN participants had lower PPT score, 6-minute walk, single-limb balance, and stair climbing than controls (all p<.05). %IMAT volume correlated inversely, and %SQAT correlated directly, with PPT. Leg %IMAT and disease status predicted 49% of PPT score. CONCLUSIONS: T2DMPN may represent a shift in adipose tissue accumulation from SQAT to IMAT depots, which is inversely associated with muscle performance and physical function.

Comparison of pelvic muscle architecture between humans and commonly used laboratory species.

INTRODUCTION AND HYPOTHESIS: Pelvic floor muscles (PFM) are deleteriously affected by vaginal birth, which contributes to the development of pelvic floor disorders. To mechanistically link these events, experiments using animal models are required, as access to human PFM tissue is challenging. In choosing an animal model, a comparative study of PFM design is necessary, since gross anatomy alone is insufficient to guide the selection. METHODS: Human PFM architecture was measured using micromechanical dissection and then compared with mouse (n = 10), rat (n = 10), and rabbit (n = 10) using the Architectural Difference Index (ADI) (parameterizing a combined measure of sarcomere length-to-optimal-sarcomere ratio, fiber-to-muscle-length ratio, and fraction of total PFM mass and physiological cross-sectional area (PCSA) contributed by each muscle). Coccygeus (C), iliocaudalis (IC), and pubocaudalis (PC) were harvested and subjected to architectural measurements. Parameters within species were compared using repeated measures analysis of variance (ANOVA) with post hoc Tukey's tests. The scaling relationships of PFM across species were quantified using least-squares regression of log-10-transformed variables. RESULTS: Based on the ADI, rat was found to be the most similar to humans (ADI = 2.5), followed by mouse (ADI = 3.3). When animals' body mass was regressed against muscle mass, muscle length, fiber length, and PCSA scaling coefficients showed a negative allometric relationship or smaller increase than predicted by geometric scaling. CONCLUSION: In terms of muscle design among commonly used laboratory animals, rat best approximates the human PFM, followed by mouse. Negative allometric scaling of PFM architectural parameters is likely due to the multifaceted function of these muscles.

Post-mortem timing of skeletal muscle biochemical and mechanical degradation.

Fresh cadaveric human tissue is a valuable resource that is used to address important clinical questions. However, it is unknown how post-mortem time impacts skeletal muscle mechanical and biochemical properties. We simulated morgue conditions in rabbits and tested the passive mechanical properties of muscle bundles, and the degradation of myosin heavy chain, collagen, and titin at specific intervals up to 7 days post-mortem. While a great deal of inter-specimen variability was observed, it was independent of post-mortem time. Passive mechanics, myosin heavy chain, and collagen content were all unaffected while the titin protein degraded up to 80% over 7 days post-mortem. These data indicate that fresh cadaveric tissue may be used for passive mechanical testing and that certain biochemical properties are unchanged up to 7 days after death.

Contribution of denervated muscle to contractures after neonatal brachial plexus injury: not just muscle fibrosis.

INTRODUCTION: We investigated the contribution of muscle fibrosis to elbow flexion contractures in a murine model of neonatal brachial plexus injury (NBPI). METHODS: Four weeks after NBPI, biceps and brachialis fibrosis were assessed histologically and compared with the timing of contracture development and the relative contribution of each muscle to contractures. Modulus of elasticity and hydroxyproline (collagen) content were measured and correlated with contracture severity. The effect of halofuginone antifibrotic therapy on fibrosis and contractures was investigated. RESULTS: Elbow contractures preceded muscle fibrosis development. The brachialis was less fibrotic than the biceps, yet contributed more to contractures. Modulus and hydroxyproline content increased in both elbow flexors, but neither correlated with contracture severity. Halofuginone reduced biceps fibrosis but did not reduce contracture severity. CONCLUSIONS: Contractures after NBPI cannot be explained solely by muscle fibrosis, arguing for investigation of alternate pathophysiologic targets for contracture prevention and treatment.

Architectural design of the pelvic floor is consistent with muscle functional subspecialization.

INTRODUCTION AND HYPOTHESIS: Skeletal muscle architecture is the strongest predictor of a muscle's functional capacity. The purpose of this study was to define the architectural properties of the deep muscles of the female pelvic floor (PFMs) to elucidate their structure-function relationships. METHODS: PFMs coccygeus (C), iliococcygeus (IC), and pubovisceral (PV) were harvested en bloc from ten fixed human cadavers (mean age 85 years, range 55-102). Fundamental architectural parameters of skeletal muscles [physiological cross-sectional area (PCSA), normalized fiber length, and sarcomere length (L(s))] were determined using validated methods. PCSA predicts muscle-force production, and normalized fiber length is related to muscle excursion. These parameters were compared using repeated measures analysis of variance (ANOVA) with post hoc t tests, as appropriate. Significance was set to α = 0.05. RESULTS: PFMs were thinner than expected based on data reported from imaging studies and in vivo palpation. Significant differences in fiber length were observed across PFMs: C = 5.29 ± 0.32 cm, IC = 7.55 ± 0.46 cm, PV = 10.45 ± 0.67 cm (p < 0.001). Average L(s) of all PFMs was short relative to the optimal L(s) of 2.7 µm of other human skeletal muscles: C = 2.05 ± 0.02 µm, IC = 2.02 ± 0.02 µm, PC/PR = 2.07 ± 0.01 µm (p = <0.001 compared with 2.7 µm; p = 0.15 between PFMs, power = 0.46). Average PCSA was very small compared with other human muscles, with no significant difference between individual PFMs: C = 0.71 ± 0.06 cm(2), IC = 0.63 ± 0.04 cm(2), PV = 0.59 ± 0.05 cm(2) (p = 0.21, power = 0.27). Overall, C had shortest fibers, making it a good stabilizer. PV demonstrated the longest fibers, suggesting that it functions to produce large excursions. CONCLUSIONS: PFM design shows individual muscles demonstrating differential architecture, corresponding to specialized function in the pelvic floor.

Weight-bearing versus nonweight-bearing exercise for persons with diabetes and peripheral neuropathy: a randomized controlled trial.

OBJECTIVE: To determine the effects of weight-bearing (WB) versus nonweight-bearing (NWB) exercise for persons with diabetes mellitus (DM) and peripheral neuropathy (PN). DESIGN: Randomized controlled trial with evaluations at baseline and after intervention. SETTING: University-based physical therapy research clinic. PARTICIPANTS: Participants with DM and PN (N=29) (mean age ± SD, 64.5±12.5y; mean body mass index [kg/m(2)] ± SD, 35.5±7.3) were randomly assigned to WB (n=15) and NWB (n=14) exercise groups. All participants (100%) completed the intervention and follow-up evaluations. INTERVENTIONS: Group-specific progressive balance, flexibility, strengthening, and aerobic exercise conducted sitting or lying (NWB) or standing and walking (WB) occurred 3 times a week for 12 weeks. MAIN OUTCOME MEASURES: Measures included the 6-minute walk distance (6MWD) and daily step counts. Secondary outcome measures represented domains across the International Classification of Functioning, Disability and Health. RESULTS: The WB group showed greater gains than the NWB group over time on the 6MWD and average daily step count (P<.05). The mean and 95% confidence intervals (CIs) between-group difference over time was 29m (95% CI, 6-51) for the 6MWD and 1178 (95% CI, 150-2205) steps for the average daily step count. The NWB group showed greater improvements than the WB group over time in hemoglobin A1c values (P<.05). CONCLUSIONS: The results of this study indicate the ability of this population with chronic disease to increase 6MWD and daily step count with a WB exercise program compared with an NWB exercise program.

Intermuscular adipose tissue is muscle specific and associated with poor functional performance.

Purpose. People with obesity, diabetes, and peripheral neuropathy have high levels of intermuscular adipose tissue (IMAT) volume which has been inversely related to physical function. We determined if IMAT is muscle specific, if calf IMAT is different between a healthy obese group (HO), a group with diabetes mellitus (D), and a group with diabetes mellitus and peripheral neuropathy (DN), and if IMAT volume or the ratio of IMAT/muscle volume is related to physical function in these groups. Methods. 10 healthy obese people, 11 with type 2 diabetes, 24 with diabetes and peripheral neuropathy, had assessments of muscle morphology, physical function and muscle performance. Results. The gastrocnemius muscle had a higher ratio of IMAT/muscle volume than any other muscle or compartment. There were no differences between groups in calf muscle or IMAT volumes. Calf IMAT was inversely related to physical performance on the 6-minute walk test (r = -0.47) and physical performance test (r = -0.36). IMAT/muscle volume was inversely related to physical performance (PPT, r = -0.44; 6 MW r = -0.48; stair power, r = -0.30). Conclusions. IMAT accumulation varies in calf muscles, is highest in the gastrocnemius muscle, and is associated with poor physical performance.

Sample size considerations in human muscle architecture studies.

INTRODUCTION: This report is a meta-analysis of the human muscle architecture literature that analyzes the number of muscles, number of subjects, and muscle fiber length coefficient of variation (CV) by body region. METHODS: Muscle fiber length data are used to make recommendations for dissection-based architectural study sample sizes. RESULTS: An average of 9 ± 10 (mean ± SD) muscles and an average of 9 ± 5 subjects were reported in the 26 studies considered. Across all studies, average fiber length CV was highly variable (18% ± 5%). This shows that sample sizes required to achieve adequate power varies by anatomical region. CONCLUSIONS: Studies involving muscle architecture should consider regional variability and effect size and determine sample size accordingly.