Body mass as a factor in stature change

Cadence matters: Influence of cadence on spinal load during running

BACKGROUND

Running exposes the body to physiological and mechanical stresses that generate musculoskeletal injuries, such as low back pain due to large spinal loading. Increasing running cadence may reduce impact forces and spinal shrinkage.

RESEARCH QUESTION

This study aimed to determine the relationship between spinal loading and running cadence.

METHODS

This cross-sectional study included 15 runners from the local community (36 ± 11 years; 23 ± 2 kg.m-2, and 8 ± 9 years of running experience) who ran for 30 min (R30) and 60 min (R60) at a constant speed (10 km.h-1). The spinal loading was assessed via fine stature variation measurements before the run (baseline) at R30 and R60. Cadence was monitored via a wristwatch. The cadence ranged from 150 to 180 steps.min-1. A t-test was used to compare stature loss between R30 and R60 (relative to baseline), and a stepwise linear regression equation was used to identify the relationship between cadence and stature variation in each instant.

RESULTS

There was a stature loss throughout the race (R30 = 5.27 ± 1.92 mm and R60 =7.51 ± 2.51 mm). A linear regression analysis revealed a negative relationship between stature loss and cadence, indicating that running at a faster cadence produces smaller spinal loading than running at slower cadences after R60 (R2 = 0.38; p<0.05).

SIGNIFICANCE

Increasing running cadence might cause less spinal loading than running with a slower cadence, which may reduce the risk of injury and back disorders in runners.

Obstetric-related lower back pain: the effect of number of pregnancy on development of chronic lower back pain, worsening of lumbar disc degeneration and alteration of lumbar sagittal balance

OBJECTIVE

This study aims to determine whether the number of pregnancies contributes to the development of chronic lower back pain, worsening the lumbar disc degeneration and altering the normal lumbar sagittal balance.

MATERIAL METHOD

There are 134 ladies participated in this study. They are divided into two groups based on their number of pregnancies (parity). All patients with chronic back pain were assessed using a visual analog scale for pain and the Oswestry Disability Index for their functional status assessment. Degenerative signs in lumbar MRI, which are Modic changes and the presence of Schmorl's node, were evaluated. Besides that, the sagittal balance of the lumbar spine was also measured via an erect lumbar plain radiograph.

RESULTS

Patients with parities < 5 were included in Group 1, and those with parities ≥ 5 in Group 2. The mean visual analog scale score of Group 2 was significantly higher than that of Group 1 (8.42 ± 1.34 vs.6.50 ± 1.61). The mean Oswestry Disability Index score in Group 2 was significantly higher than that of Group 1 (29.87 ± 6.75 vs.18.41 ± 7.97). This relationship between the groups in terms of Modic change was statistically significant. The relationship between the groups regarding the presence of Schmorl's nodes was also statistically significant. The difference between the groups in terms of sagittal balance parameters was not statistically significant.

CONCLUSION

Chronic lower back pain is significantly worse and associated with more disability in patients with more than five previous pregnancies. MRI degenerative changes are also significantly higher in these grand multipara groups.

Overweight Impairs Postural Control of Female Night Workers

Objectives  To verify the relationships between sleep duration (Total Sleep Time - TST) and postural control of female night workers before and after shift. As well as, to verify if there is an influence of the body mass index (BMI) on the postural control of these female workers before and after shift. Methods  A total of 14 female night workers (mean age: 35.0 ± 7.7 years) were evaluated. An actigraph was placed on the wrist to evaluate the sleep-wake cycle. The body mass and height were measured, and BMI was calculated. Postural control was evaluated by means of a force platform, with eyes opened and eyes closed before and after the 12-hour workday. Results  There was an effect of the BMI on the velocity and the center of pressure path with eyes opened before ( t  = 2.55, p  = 0.02) and after ( t  = 4.10, p  < 0.01) night work. The BMI impaired the velocity and the center of pressure path with eyes closed before ( t  = 3.05, p  = 0.01; t  = 3.04, p  = 0.01) and after ( t  = 2.95, p  = 0.01; t  = 2.94, p  = 0.01) night work. Furthermore, high BMI is associated with female workers' postural sway ( p  < 0.05). Conclusion  Therefore, high BMI impairs the postural control of female night workers, indicating postural instability before and after night work.

Childhood Obesity and Incorrect Body Posture: Impact on Physical Activity and the Therapeutic Role of Exercise

Obesity is associated with various dysfunctions of the organism, including musculoskeletal problems. In this narrative review, we aim to consider postural problems in children and adolescents with obesity, focusing on the relationship with its negative impact on physical activity, and to discuss the role of exercise as a therapeutic approach. The body reacts to excess weight by changing its normal balance, and the somatosensory system of children with obesity is forced to make major adjustments to compensate for postural problems. These adaptations become more difficult and tiring if activities that require continuous postural changes and multi-tasking are engaged in. Children with obesity have less body control and functional ability due to the excess fat mass, which reduces their ability to perform motor skills and take part in physical activity. Appropriate early interventions for the management of musculoskeletal problems are needed to ensure healthy growth and to prevent comorbidities in childhood and adulthood. Prevention programs must be based not only on the reduction of body weight but also on the definition of correct postural habits from an early age. It is equally important to provide correct information on the types and doses of physical activity that can help prevent these problems.

EXPRESS: Does physical weight alter the mental representation of the body? Evidence from motor imagery in obesity

OBJECTIVE

Obesity is a clinical condition that impacts severely the physical body. However, evidence related to the mental representation of the body in action is scarce. The few available studies only focus on avoiding obstacles, rather than participants imagining their own body.

METHOD

To advance knowledge in this field, we assessed the performance of twenty-two individuals with obesity compared to thirty individuals with a healthy weight in two tasks that implied different motor (more implicit vs. more explicit) imagery strategies. Two tasks were also administered to control for visual imagery skills, to rule out confounding factors. Moreover, we measured body uneasiness, through a standard questionnaire, as body image negativity could impact on other body representation components.

RESULTS

Our findings do not show differences in the motor imagery tasks between individuals with obesity and individuals with healthy weight. On the other hand, some differences emerge in visual imagery skills. Crucially, individuals with obesity did report a higher level of body uneasiness.

CONCLUSIONS

Despite a negative body image and visual imagery differences, obesity per se does not impact on the representation of the body in action. Importantly, this result is independent from the level of awareness required to access the mental representation of the body.

A cross-sectional analysis of the muscle strength, spinal shrinkage, and recovery during a working day of military police officers

OBJECTIVE

Military personnel has a large prevalence of back pain, especially those involved in patrolling routines, as they wear heavy protective equipment. Patrolling includes long periods of sustaining the protective equipment in a sitting or in a motor vehicle (motorcycle or car). Thus, understanding spinal loading of military police officers after patrolling by car (CAR; n = 14), motorcycle (MOT; n = 14), and administrative (ADM; n = 14) routines is relevant to establish preventive strategies.

METHODS

The torque of the trunk and working and anthropometric characteristics were assessed to explain spinal loading using stature variation measures. Precise stature measures were performed before and after a 6 h journey (LOSS) and 20 min after a resting posture (RECOV). The trunk extensor (PTE BM-1 ) and flexor (PTF BM-1 ) muscles' isometric peak torque were measured before the working journey.

RESULTS

The LOSS was similar between CAR and MOT (4.8 and 5.8 mm, respectively) after 6 h of patrolling. The ADM presented the lowest LOSS (2.8 mm; P < .05). No changes in RECOV between groups were observed (P > .05). Vibration may explain the greater spinal loading involved in patrolling in comparison to the ADM. A GLM analysis revealed that BMI was the only explanatory factor for stature loss. No independent variables explained RECOV. The ability of the trunk muscles to produce force did not influence LOSS or RECOV.

CONCLUSIONS

Military police officers involved in patrolling may require greater post-work periods and strategies designed to reduce the weight of the protective apparatus to dissipate spinal loading. The external load used in patrolling is a relevant spinal loading factor.

Physical Performance, Anthropometrics and Functional Characteristics Influence the Intensity of Nonspecific Chronic Low Back Pain in Military Police Officers

Background: Chronic low back pain (CLBP) is a serious problem in Military Police Officers (MPO), which accounts for up to 45% of the sick leave rates. It has been assumed that the strength and the endurance of trunk flexor and extensor muscles are CLPB key factors, but it is not known whether these attributes are related to pain intensity. It was aimed to determine whether the strength and endurance of trunk flexor and extensor muscles differ in MPO with no pain (CON; n = 24), moderate (MOD; n = 42), and severe (SEV; n = 37) nonspecific chronic low back pain (CLBP). Methods: The peak torque and endurance test of trunk flexor (PTF.BM⁻¹) and extensor (PTE.BM⁻¹) muscles were compared. A multiple regression analysis was used to identify pain intensity predictors in all groups (PAIN) and according to pain intensity (MOD and SEV). Results: The PTF.BM⁻¹ was negatively related to pain and was a significant predictor, irrespective of pain intensity (PAIN). Conclusion: When pain intensity was considered the PTF.BM⁻¹ and PTE.BM⁻¹ explained the pain in the MOD, while the PTE.BM⁻¹ and service time explained pain intensity in the SEV. Endurance of the flexor and extensor muscles was not related to pain intensity. These results indicated that training protocols must emphasize specific strengthening routines.

Balance Control in Obese Subjects during Quiet Stance: A State-of-the Art

Obese individuals are characterized by a reduced balance which has a significant effect on a variety of daily and occupational tasks. The presence of excessive adipose tissue and weight gain could increase the risk of falls; for this reason, obese individuals are at greater risk of falls than normal weight subjects in the presence of postural stress and disturbances. The quality of balance control could be measured with different methods and generally in clinics its integrity is generally assessed using platform stabilometry. The aim of this narrative review is to present an overview on the state of art on balance control in obese individuals during quiet stance. A summary of knowledge about static postural control in obese individuals and its limitations is important clinically, as it could give indications and suggestions to improve and personalize the development of specific clinical programs.

Risk Factors of Secondary Lumbar Discectomy of a Herniated Lumbar Disc after Lumbar Discectomy

Objective

To study risk factors of secondary lumbar discectomy (LD) for recurrent herniated lumbar disc (HLD) and identify methods to lower the rate of recurrence.

Methods

Data from 160 patients who underwent primary LD were collected retrospectively. Demographic features, radiologic findings including Pfirrmann disc degeneration, and surgical information were analyzed to compare risks between revision and non-revision patients.

Results

The revision rate was 15% (24 patients), and the mean follow-up was 28.3 months. HLD recurrence was not related to any demographic characteristics. Primary and secondary LD were most common at the L4–5 level, but the level of operation was not significantly associated with revision. Primary LD most commonly had a Pfirrmann disc degeneration grade of 3, followed by 4. For recurrent HLD, Pfirrmann grade 4 was most common and was statistically significant (p<0.05). A body mass index (BMI) over 30 was considered obese and was significantly related with HLD revision (p<0.05).

Conclusion

Patients with high BMI or severe disc degeneration should be informed of HLD revision.

Postural Changes After Abdominoplasty in Morbid Obese Patients

BACKGROUND

In the multidisciplinary treatment of obesity, the role of a plastic surgeon is to remove the excess of skin after weight loss to obtain cosmetic, functional, and psychological benefits. Obesity modifies body geometry, increases the mass of different segments, and imposes functional limitations in life activities that may predispose the obese to injury. The authors evaluated the postural conditions of obese patients, before and 12 months after surgery.

METHODS

The study included 15 obese patients of both genders affected by class II obesity. Postural function was evaluated preoperatively and 12 months postoperatively. Patients underwent conventional abdominoplasty surgical procedure. In all patients, plantar pressure distribution and balance (stabilometric test) were evaluated before and 3 months after surgery.

RESULTS

The static pedobarographic revealed a significant reduction in forefoot peak pressure; total plantar force; rearfoot plantar force percentage; midfoot plantar force percentage; and forefoot, midfoot, and rearfoot plantar contact areas percentage 3 months after surgery; the dynamic's one showed a reduction in the first metatarsal peak pressure and plantar contact. The stabilometric values showed a reduction in the range of center of foot pressure (CP) displacement along y axis, the average displacement of the CP speed from the mean (RMS y velocity), and CP mean peak in the condition of vision.

CONCLUSIONS

Our study demonstrates the beneficial effect of dermolipectomies and the consequential weight loss on postural stability of obese men. Such findings may support the hypothesis that dermolipectomy may improve postural stability with and without vision. The data demonstrate that the benefits are related to the magnitude of the resected tissue.

Spasm and flexion-relaxation phenomenon response to large lifting load during the performance of a trunk flexion-extension exercise

BACKGROUND

The flexion relaxation phenomenon (FRP) has been widely investigated. Nevertheless, no study has been reported on the FRP as well as spasm response to large lifting load. The aim of this study was to evaluate the effect of large lifting load on the FRP response and spasm during execution of a flexion-extension exercise.

METHODS

Twenty-two healthy male university students without low back pain history participated this study. Subjects randomly performed three trials of trunk flexion-extension cycles of 5 s flexion and 5 s extension in each of 4 conditions (three large lifting loads of 15, 20 and 25 kg and one lifting load of 0 kg for comparison). Surface EMG from bilateral erector spinae was recorded during the performance of a trunk anterior flexion-extension exercise. The relaxation phase was determined through the onset of electromyography (EMG) signals. Spasm was evaluated in the relaxation period. The mean normalized electromyography (NEMG) was derived from the raw EMG.

RESULTS

Spasm was observed in more than 45% of the individuals and the intensity of muscle activation was increased by more than 78% in the relaxation phase.

CONCLUSIONS

A large lifting load could lead to a high prevalence of spasms as well as a high intensity of muscle activations on erector spinae muscle in the relaxation period, which may be associated with the development of low back disorder during the performance of a flexion-extension exercise.

Factors influencing diurnal variation in height among adults

This study evaluates height loss during the day in light of variables assessable through participant self-report. Participants were 19 female and 15 male staff and students who met with us twice with a mean interval between measurement sessions of 6.96h (SD=0.86). Hypotheses were evaluated using two-stage least squares regression analysis (SYSTAT 10). Males and females lost similar amounts of height between sessions (male,x¯=6.9mm;female,x¯=7.4mm). Among factors considered to impact overall height loss, sleep duration (Adj. R²=0.181, p=0.022) and height (Adj. R²=0.121, p=0.048) were useful in univariate analyses, though they were not significant in any models that included variables other than sex. Judging from log-transformed BMI variation, heavier males and females lost more height (F_{(2, 31)}=4.59, Adj. R²=0.179, p=0.018). Among factors anticipated to reduce height loss by acting prior to morning measurements, only time spent walking was significantly associated (β=2.6±0.8mm, t=3.16, p=0.004) when included as a predictor along with sex (p=0.17) and log-BMI (p=0.003). This model explained about 38% of height loss variance. None of the factors considered as potentially acting between measurement sessions showed statistically significant influences when included in the model just described, though predictor coefficients were in the anticipated direction. Results suggest that self-reported activities may be an important supplement to anthropometric studies, both for planning and later evaluation, particularly in large studies.

Associations between Obesity and Spinal Diseases: A Medical Expenditure Panel Study Analysis

Background: The link between body weight status and spinal diseases has been suggested by a number of cross-sectional and cohort studies with a limited range of patient populations. No population-representative samples have been used to examine the link between obesity and spinal diseases. The present study is based on a nationally representative sample drawn from the Medical Expenditure Panel Survey. Methods: Using the cross-sectional sample of the 2014 Medical Expenditure Panel Study, we built four weighted logistic regression analyses of the associations between body weight status and the following four spinal diseases: low back pain, spondylosis, other cervical disorders and intervertebral disc disorder (IDD). Each respondent's body weight status was used as the key independent variable with three categories: normal/underweight, overweight, and obese. We controlled for marital status, gender, age, smoking status, household income, health insurance coverage, educational attainment and the use of health services for other major categories of diseases. Results: A total sample of 23,048 respondents was used in our analysis. Overweight and obese respondents, as compared to normal/underweight respondents, were more likely to develop lower back problems (Overweight: logged odds = 0.218, p < 0.01; Obese: logged odds = 0.395, p < 0.001) and IDD (Overweight: logged odds = 0.441, p < 0.05; Obese: logged odds = 0.528, p < 0.001). The associations between bodyweight status and spondylitis were statistically insignificant (Overweight: logged odds = 0.281, p = 0.442; Obese: logged odds = 0.680, p = 0.104). The associations between body weight status and other cervical disorders (Overweight: logged odds = -0.116, p = 0.304; Obese: logged odds = -0.160, p = 0.865) were statistically insignificant. Conclusions: As the first study using a national sample to study bodyweight and spinal diseases, our paper supports the hypothesis that obesity adds to the burden of low back pain and IDD. Longitudinal and interventional studies are needed to understand the specific mechanisms behind these positive associations.

Influence of Obesity on Postural Stability in Young Adults

OBJECTIVES

The purpose of this study was to determine whether obesity is associated with less postural stability in young adults, and whether it is influenced by anterior pelvic tilt angle and sensory dysfunction.

METHODS

Center of gravity (COG) velocity and total sway distance with eyes open or eyes closed on firm or foam floors were determined in 12 obese individuals and 12 individuals with normal weight.

RESULTS

On firm and foam floors with eyes closed, center of gravity velocity and total sway distance were significantly greater in the obese group than in the normal-weight group. However, on firm and foam floors with eyes open, center of gravity velocity and total sway distance were not significantly different in the two groups.

CONCLUSION

The clinical implication of our findings is that obese young adults exhibit poor postural stability. Our findings also suggested that postural instability in obese individuals is associated with increased lordosis due to abdominal fat and poor integration of plantar somatosensory input.

Symptoms and musculoskeletal diseases in hospital nurses and in a group of university employees: a cross-sectional study

BACKGROUND

Most studies have shown that nurses have a higher risk of developing musculoskeletal symptoms compared with other occupational groups.

AIM

A cross-sectional study was performed to gain more insight into the prevalence rates of musculoskeletal disorders (MSDs) in nurses.

METHODS

The presence of musculoskeletal symptoms was revealed by personal interviews in a sample of 177 hospital nurses and in a reference group of 185 university employees. Musculoskeletal diseases were based on radiological examinations in all subjects.

RESULTS

Lower back pain (61% vs 42.2%) was the most frequently reported symptom, followed by neck pain (48.6% vs 38.4%) and shoulder pain (36.7% vs 25.9%), with a significantly higher prevalence in nurses. Women had about a 2-fold risk of upper limb region and neck pain compared with men. The most common abnormal findings on radiological examinations were disc herniations (n = 40).

CONCLUSIONS

Nurses showed a significantly higher risk of MSDs. Prevalence rates in nurses increased significantly with age. Musculoskeletal symptoms were also common in university employees. This suggests the need for effective intervention strategies involving workers' active participation, in order to improve the process and organization of work and promote a positive psychosocial work environment.

Kinematic analysis of ankle stiffness in subjects with and without flat foot

BACKGROUND

Although the magnitude of ankle motion is influenced by joint congruence and ligament elasticity, there is a lack of understanding on ankle stiffness between subjects with and without flat foot.

OBJECTIVE

This study investigated a quantified ankle stiffness difference between subjects with and without flat foot.

METHODS

There were forty-five age- and gender-matched subjects who participated in the study. Each subject was seated upright with the tested foot held firmly onto a footplate that was attached to a torque sensor by the joint-driving device.

RESULTS

The flat foot group (mean ± standard deviation) demonstrated increased stiffness during ankle dorsiflexion (0.37 ± 0.16 for flat foot group, 0.28 ± 0.10 for control group; t=-2.11, p=0.04). However, there was no significant group difference during plantar flexion (0.35 ± 0.15 for flat foot group, 0.33 ± 0.07 for control group; t=0.64, p=0.06).

CONCLUSION

The results of this study indicated that the flat foot group demonstrated increased ankle stiffness during dorsiflexion regardless of demographic factors. This study highlights the need for kinematic analyses and joint stiffness measures during ankle dorsiflexion in subjects with flat foot.

Prevalence, consequences and predictors of low back pain among nurses in a tertiary care setting

PURPOSE

Nursing is a profession with high incidence and prevalence of low back pain (LBP), with its medical and professional consequences. These prevalence rates vary among countries, and with various measurements have been used to determine LBP. Individual and work-related factors are regarded as causal factors for many back injuries. The aims of study this were: (1) to estimate the prevalence of LBP using different measures, (2) to determine medical and professional consequences of LBP, and (3) to determine the associated factors and significant predictors of LBP.

METHODS

A cross-sectional study was conducted among 254 nurses from different departments/wards at Hamad General Hospital (HGH), Doha, Qatar over two months (February and March, 2015). A self-administered modified Nordic questionnaire was used to collect data regarding five different measures of LBP, its medical and occupational consequences and individual/lifestyle and work-related risk factors of LBP. Descriptive and analytic statistical analyses were done using chi-square and multivariate logistic regression techniques. Significance was considered at p ≤ 0.05.

RESULTS

The findings of this study broadly confirm the high levels of back pain in nursing, with a one-year prevalence of LBP of 54.3 % for LBP of at least one day, 26.8 % for chronic LBP, 18.1 % for sick leave seeking LBP, and 34.3 % for medical treatment seeking LBP. Difficult or impossible activities of daily living were reported due to LBP in climbing stairs (50.7 %), walking (42.8 %), standing up (39.9 %), sleeping (33.3 %), getting out of bed (30.4 %) and wearing clothes (20.3 %). Work stop due to LBP was reported by 76.8 % of nurses, with 2.03 ± 3.09 days within the last year. Treatment was sought in 58.7 % by medical care, and 15.9 % by physiotherapy, while seeking rest days and/or sick leave was sought in 50.8 % of nurses with LBP. Sports practice (p = 0.003), office work (p < 0.001) and exposure to physical stress (p = 0.002) were the only significant predictors of LBP among nurses, when logistic regression analysis was conducted.

CONCLUSION

The prevalence of LBP among nurses at HGH is high and should be actively addressed, however, it was not a major cause of sick leave. Preventive measures should be taken to reduce the risk of lower back pain, such as arranging proper rest periods, educational programs to teach the proper use of body mechanics and sports activity programs.

Kinematic, Cardiopulmonary, and Metabolic Responses of Overweight Runners While Running at Self-Selected and Standardized Speeds

OBJECTIVE

To determine the differences in kinematic, cardiopulmonary, and metabolic responses between overweight and healthy weight runners at a self-selected and standard running speed.

DESIGN

Comparative descriptive study.

SETTING

Tertiary care institution, university-affiliated research laboratory.

PARTICIPANTS

Overweight runners (n = 21) were matched with runners of healthy weight (n = 42).

METHODS

Participants ran at self-selected and standardized speeds (13.6 km/h). Sagittal plane joint kinematics were captured simultaneously with cardiopulmonary and metabolic measures using a motion capture system and portable gas analyzer, respectively.

MAIN OUTCOME MEASUREMENTS

Spatiotemporal parameters (cadence, step width and length, center of gravity displacement, stance time) joint kinematics, oxygen cost, heart rate, ventilation and energy expenditure.

RESULTS

At the self-selected speed, overweight individuals ran slower (8.5 ± 1.3 versus 10.0 ± 1.6 km/h) and had slower cadence (163 versus 169 steps/min; P < .05). The sagittal plane range of motion (ROM) for flexion-extension at the ankle, knee, hip, and anterior pelvic tilt were all less in overweight runners compared to healthy weight runners (all P < .05). At self-selected speed and 13.6 km/h, energy expenditure was higher in the overweight runners compared to their healthy weight counterparts (P < .05). At 13.6 km/h, only the frontal hip and pelvis ROM were higher in the overweight versus the healthy weight runners (P < .05), and energy expenditure, net energy cost, and minute ventilation were higher in the overweight runners compared to the healthy weight runners (P < .05).

CONCLUSION

At self-selected running speeds, the overweight runners demonstrated gait strategies (less joint ROM, less vertical displacement, and shorter step lengths) that resulted in cardiopulmonary and energetic responses similar to those of healthy weight individuals.

Effects of seated lumbar extension postures on spinal height and lumbar range of motion during prolonged sitting

Prolonged sitting during sedentary work has been reported as a potential risk factor for low back pain. Furthermore, prolonged sitting can result in both reduced spinal height (SH) and lumbar range of motion (LROM). This study compared the effects of no intervention (control) with two recovery postures on SH and LROM (flexion and extension) during prolonged sitting. Twenty-four participants were randomly assigned to three interventions for three consecutive days. The interventions comprised two seated lumbar extension recovery postures (unsupported sustained and supported dynamic lumbar extension postures) and a control. Both interventions facilitated a relatively short recovery period for both SH and LROM. Supported dynamic lumbar extension conditions significantly helped SH recovery, as compared with control condition, after the first recovery posture intervention, and both postures have potential to maintain LROM. However, both postures failed to induce SH recovery over an extended time.

PRACTITIONER SUMMARY

Unsupported sustained lumbar extension and supported dynamic lumbar extension postures may serve as effective and practical methods for reducing rate of SH loss and maintaining LROM. However, these postures should be further examined in various ‘doses’ to define optimal protocol for effectively minimising SH loss over time.

Risk factors of acute and overuse musculoskeletal injuries among young conscripts: a population-based cohort study

BACKGROUND

Military service in Finland is compulsory for all male citizens and annually about 80% of 19-year-old men enter into the service. The elevated risk for many chronic diseases and loss of function among those who are inactive and unfit can be often detected already in youth. On the other hand, activity-induced injuries among young are true public health issue. The purpose of the present prospective cohort follow-up study was to evaluate predictive associations between acute or overuse injuries and their various intrinsic risk factors.

METHODS

Four successive cohorts of conscripts who formed a representative sample of Finnish young men were followed for 6 months. At the beginning of the service, the risk factors of injuries were measured and recorded and then the acute and overuse injuries treated at the garrison clinic were identified. Predictive associations between injuries and their risk factors were examined by multivariate Cox's proportional hazard models.

RESULTS

Of the 1411 participants, 27% sustained an acute injury and 51% suffered from overuse injury. Concerning acute injuries, highest risk for severe injuries were detected among conscripts with low fitness level in both the standing long-jump and push-up tests (hazard rate, HR=5.9; 95% CI: 1.6‒21.3). A history of good degree in school sports was not a protective factor against acute injuries. High waist circumference and, on the other hand, being underweight according to BMI increased the HR for overuse injuries. Brisk leisure time physical activity before military entry was a protective factor against overuse injuries. Poor result in Cooper's test was a warning signal of elevated risk of overuse injuries.

CONCLUSION

We confirmed previous findings that low level of physical fitness is predictor for musculoskeletal injuries during intensive physical training. The U-shaped relationship between body composition and overuse injuries was noticed indicating that both obesity and underweight are risk factors for overuse injuries. Persons with excellent sports skills according to their earlier degrees in school sports had similar HR for acute injuries than those with poorer degrees. This indicates that school-age sports skills and fitness do not carry far and therefore preventive programmes are needed to prevent activity-induced injuries.

The Link between Musculoskeletal Pain, Lifestyle Behaviors, Exercise Self-Efficacy, and Quality of Life in Overweight and Obese Individuals

Objective

To determine the extent musculoskeletal (MS) pain in the low back and knee (weight-bearing (WB) joints), shoulder and wrist (non-weight bearing joints), and exercise self-efficacy mediates associations between overweight and obesity levels based on BMI (4 levels: overweight, obese class I, II, or III), physical function, emotional role, social interference, and physical activity (PA) levels.

Design

Cross-sectional study.

Setting

Four long-term nursing home facilities in the Northeast U.S.

Participants

99 overweight or obese (BMI > 25) nursing home employees.

Interventions

Self-reported survey administered to employees who met inclusion and exclusion criteria.

Main Outcome Measure(s)

General health status, physical function, emotional role, Exercise Self-Efficacy Scale (ESE), physical activity (PA), and frequency of pain at each joint.

Results

Reported pain frequency were 66.3%, 54.4%, 42.2%, and 24.1% for lower back, knee, shoulder, and wrist, respectively. Higher obesity levels were associated with lower physical function (r=−0.109, p=0.284). PA decreased with higher obesity levels (r=−0.248, p<0.05), particularly in moderate PA (r=−0.293, p<0.05). Obesity was associated with a lower ESE (r=−0.239, p<0.05). Wrist pain significantly mediated the effect of obesity on moderate physical function, emotional role, and ESE. ESE was a significant mediator between obesity and moderate and vigorous PA.

Conclusions

Overweight and obese nursing home employees are at higher risk for developing musculoskeletal disorders due to high demand, low control jobs, and the associated biomedical compromises while working. To increase the effectiveness of weight loss interventions for this population, the mediating effects of MS pain with higher levels of obesity should be considered.

Immediate effects of manual traction on radiographically determined joint space width in the hip joint

OBJECTIVE

The purpose of this study was to investigate the immediate effects of manual traction of the hip joint on joint space width (JSW) on asymptomatic subjects.

METHODS

Asymptomatic, healthy male volunteers (n = 15), aged 25 to 34 years were included in this study. Three radiographs were obtained with the subjects in the supine position, before and after loading with 10% of his body weight, and after manual traction on only the right hip joint. Joint space width was measured by a radiologist at the point described by Jacobson and Sonne-Holm.

RESULTS

There were significant changes in JSW on the right hip joint and left hip joint between the baseline (before loading) and immediately after loading. We also observed a significantly increased JSW on only the right hip joint between periods that followed loading and manual traction on the right hip joint. There was no significant change in JSW on the left hip joint between periods that followed loading and manual traction on the right hip joint.

CONCLUSIONS

The results of this study suggest that a significant increase in JSW in young, healthy male patients can occur immediately after manual traction of the hip joint.

Spine curvature analysis between participants with obesity and normal weight participants: a biplanar electromagnetic device measurement

To analyse and compare standing thoracolumbar curves in normal weight participants and participants with obesity, using an electromagnetic device, and to analyse the measurement reliability.

MATERIAL AND METHODS

Cross-sectional study was carried out. 36 individuals were divided into two groups (normal-weight and participants with obesity) according to their waist circumference. The reference points (T1-T8-L1-L5 and both posterior superior iliac spines) were used to perform a description of thoracolumbar curvature in the sagittal and coronal planes. A transformation from the global coordinate system was performed and thoracolumbar curves were adjusted by fifth-order polynomial equations. The tangents of the first and fifth lumbar vertebrae and the first thoracic vertebra were determined from their derivatives. The reliability of the measurement was assessed according to the internal consistency of the measure and the thoracolumbar curvature angles were compared between groups.

RESULTS

Cronbach's alpha values ranged between 0.824 (95% CI: 0.776-0.847) and 0.918 (95% CI: 0.903-0.949). In the coronal plane, no significant differences were found between groups; however, in sagittal plane, significant differences were observed for thoracic kyphosis.

CONCLUSION

There were significant differences in thoracic kyphosis in the sagittal plane between two groups of young adults grouped according to their waist circumference.

Does obesity affect outcomes of treatment for lumbar stenosis and degenerative spondylolisthesis? Analysis of the Spine Patient Outcomes Research Trial (SPORT)

STUDY DESIGN

Retrospective subgroup analysis of prospectively collected data according to treatment received.

OBJECTIVE

The purpose of this study was to determine whether obesity affects treatment outcomes for lumbar stenosis (SpS) and degenerative spondylolisthesis (DS).

SUMMARY OF BACKGROUND DATA

Obesity is thought to be associated with increased complications and potentially less favorable outcomes after the treatment of degenerative conditions of the lumbar spine. This, however, remains a matter of debate in the existing literature.

METHODS

An as-treated analysis was performed on patients enrolled in the Spine Patient Outcomes Research Trial for the treatment of SpS or DS. A comparison was made between patients with a body mass index (BMI) of less than 30 ("nonobese," n = 373 SpS and 376 DS) and those with a BMI of 30 or more ("obese," n = 261 SpS and 225 DS). Baseline patient characteristics, intraoperative data, and complications were documented. Primary and secondary outcomes were measured at baseline and regular follow-up time intervals up to 4 years. The difference in improvement over baseline between surgical and nonsurgical treatment (i.e., treatment effect) was determined at each follow-up interval for the obese and nonobese groups.

RESULTS

At 4-year follow-up, operative and nonoperative treatment provided improvement in all primary outcome measures over baseline in patients with BMI of less than 30 and 30 or more. For patients with SpS, there were no differences in the surgical complication or reoperation rates between groups. Patients with DS with BMI of 30 or more had a higher postoperative infection rate (5% vs. 1%, P = 0.05) and twice the reoperation rate at 4-year follow-up (20% vs. 11%, P = 0.01) than those with BMI of less than 30. At 4 years, surgical treatment of SpS and DS was equally effective in both BMI groups in terms of the primary outcome measures, with the exception that obese patients with DS had less improvement from baseline in the 36-Item Short Form Health Survey (SF-36) physical function score than nonobese patients (22.6 vs. 27.9, P = 0.022). With nonoperative treatment, patients with SpS with BMI of 30 or more did worse in regard to all 3 primary outcome measures, and patients with DS with BMI of 30 or more had similar SF-36 bodily pain scores but less improvement over baseline in the SF-36 physical function and Oswestry Disability Index scores. Treatment effects for SpS and DS were significant within each BMI group for all primary outcome measures in favor of surgery. Obese patients had a significantly greater treatment effect than nonobese patients with SpS (Oswestry Disability Index, P = 0.037) and DS (SF-36 PF, P = 0.004) largely due to the relatively poor outcome of nonoperative treatment in obese patients.

CONCLUSION

Obesity does not affect the clinical outcome of operative treatment of SpS. There are higher rates of infection and reoperation and less improvement from baseline in the SF-36 physical function score in obese patients after surgery for DS. Nonoperative treatment may not be as effective in obese patients with SpS or DS.

Influência da obesidade e da força de preensão palmar no equilíbrio postural estático de idosas ativas

O objetivo deste estudo foi investigar a influência da obesidade e da força de preensão palmar (FPP) no equilíbrio postural estático de idosas ativas nas condições de olhos abertos e fechados. Participaram 31 idosas (16 eutróficas e 15 obesas). A idade média e o Índice de Massa Corpórea (IMC) das eutróficas foram, respectivamente, 68,3±2,7 anos e 23,4±1,6kg/m², e das obesas 69,1±2,7 anos e 33,5±3kg/m². A FPP foi avaliada usando um dinamômetro (JAMAR). O equilíbrio postural estático foi avaliado usando um sistema tridimensional nas condições de olhos abertos (OA) e fechados (OF), durante 90 segundos cada condição. A FPP das idosas eutróficas foi 25,1±4,6kgf e das obesas foi 24,8±5,2kgf, não havendo diferenças significativas. No equilíbrio postural, foram observadas diferenças significativas entre os grupos apenas no deslocamento máximo a-p com AO (p=0,04) e OF (p<0,01), com as idosas obesas apresentando menor deslocamento a-p em relação às eutróficas. Não houve correlação entre o deslocamento máximo a-p com IMC e a FPP. No presente estudo FPP não influenciou o equilíbrio postural estático, enquanto a obesidade foi fator determinante de menor deslocamento ântero-posterior de idosas ativas.

The effects of upper limb loading on spinal shrinkage during treadmill walking

INTRODUCTION

Everyday activities such as walking may elicit spinal shrinkage in an order of magnitude that has been related to lower back pain. The present study aims to compare the effects of unloaded treadmill walking with walking carrying loads representing everyday shopping tasks.

MATERIALS AND METHODS

Walking tasks were performed on seven healthy males and motion analysis was used to track four reflective markers at 100 Hz, dividing the spine into three segments. Static data was collected in 5-min intervals over a 30-min period.

RESULTS

Total spinal length and lumbar segment decreased with respect to time (p < 0.001). Load affected the percentage length change at each spinal segment (p < 0.005), with the lumbar segment showing greatest height loss at the highest load. The upper and lower thoracic segments showed greater anterior lean with the heavier loads (p = 0.000) and the lumbar segment showed the opposite trend (p = 0.000).

CONCLUSION

Results suggest that the body adopts less anterior lean with an immediate load-bearing demand, to decrease the necessary extension moment generated by the spinal extensors for spinal stability. Further postural alteration in the same direction is observed with prolonged loading. In combination with lumbar spinal shrinkage, such postural changes are likely to increase the loading on the facet joints and subsequently unload the discs which may be beneficial for those with low back pain.

Obesity, mechanical and strength relationships to postural control in adolescence

There is preliminary evidence that BMI is positively correlated with movement variability of standing posture. However, this negative effect of obesity on postural control may be mediated by the change in other body scale variables (e.g., mechanical and fitness) that also occur with changes in BMI. This study investigated the influence of selected body scale (height, body mass, BMI), body composition (body fat percentage), mechanical (moment of inertia - MI) and strength (S) variables as predictors of the control of postural motion in adolescents. 125 healthy adolescents (65 boys, 60 girls) with a wide range of BMI (13.8-31.0 kg/m(2)) performed a battery of tests that assessed body composition, anthropometry, muscular strength and postural control. Multiple measures of postural motion variability were derived for analysis with body scale, mechanical and lower extremity strength variables separately for boys and girls. BMI, height and body mass, considered both separately and collectively, were poor and/or inconsistent predictors of variability in all three posture tasks. However, the ratio of lower extremity strength to whole body moment of inertia showed the highest positive correlation to most postural variability measures in both boys and girls and these effects were strongest in the less stable tasks of single leg standing and recovery of stance. Our findings support the hypothesis that diminished lower extremity strength to mechanical constraint ratio compromises the robustness of the strength to body scale relation in movement and postural control.

Obese elderly women exhibit low postural stability: a novel three-dimensional evaluation system

OBJECTIVE

The aim of this study was to evaluate the multisegmental static postural balance of active eutrophic and obese elderly women using a three-dimensional system under different sensory conditions.

METHODS

A cross-sectional study was conducted on 31 elderly women (16 eutrophic and 15 obese) aged 65 to 75 years. The following anthropometric measurements were obtained: weight, height, waist and hip circumference, and handgrip strength. The physical activity level was evaluated using the International Physical Activity Questionnaire. Body composition was measured using the deuterium oxide dilution technique. The Polhemus(®) Patriot (three-dimensional) equipment was used to measure the parameters of postural balance along the anteroposterior and laterolateral axes. The data acquisition involved one trial of 60 s to test the limit of stability and four trials of 90 s each under the following conditions: (1) eyes open, stable surface; (2) eyes closed, stable surface; (3) eyes open, unstable surface; and (4) eyes closed, unstable surface.

RESULTS

For the limit of stability, significant differences were observed in the maximum anteroposterior and laterolateral displacement (p<0.01) and in the parameter maximum anteroposterior displacement in the eyes closed stable surface condition (p<0.01) and maximum anteroposterior and laterolateral displacement in the eyes open unstable surface (p<0.01 and p = 0.03) and eyes closed unstable surface (p<0.01 and p<0.01) conditions.

CONCLUSIONS

Obese elderly women exhibited a lower stability limit (lower sway area) compared with eutrophic women, leaving them more vulnerable to falls.

Effects of obesity and chronic low back pain on gait

Background

Obesity is often associated with low back pain (LBP). Despite empirical evidence that LBP induces gait abnormalities, there is a lack of quantitative analysis of the combined effect of obesity and LBP on gait. The aim of our study was to quantify the gait pattern of obese subjects with and without LBP and normal-mass controls by using Gait Analysis (GA), in order to investigate the cumulative effects of obesity and LBP on gait.

Methods

Eight obese females with chronic LBP (OLG; age: 40.5 ± 10.1 years; BMI: 42.39 ± 5.47 Kg/m²), 10 obese females (OG; age: 33.6 ± 5.2 years; BMI: 39.26 ± 2.39 Kg/m²) and 10 healthy female subjects (CG; age: 33.4 ± 9.6 years; BMI: 22.8 ± 3.2 Kg/m²), were enrolled in this study and assessed with video recording and GA.

Results and Discussion

OLG showed longer stance duration and shorter step length when compared to OG and CG. They also had a low pelvis and hip ROM on the frontal plane, a low knee flexion in the swing phase and knee range of motion, a low dorsiflexion in stance and swing as compared to OG. No statistically significant differences were found in ankle power generation at push-off between OLG and OG, which appeared lower if compared to CG. At hip level, both OLG and OG exhibited high power generation levels during stance, with OLG showing the highest values.

Conclusions

Our results demonstrated that the association of obesity and LBP affects more the gait pattern than obesity alone. OLG were in fact characterised by an altered knee and ankle strategy during gait as compared to OG and CG. These elements may help optimizing rehabilitation planning and treatment in these patients.

The relationships between measures of stature recovery, muscle activity and psychological factors in patients with chronic low back pain

Individuals with low back pain (LBP) often exhibit elevated paraspinal muscle activity compared to asymptomatic controls during static postures such as standing. This hyperactivity has been associated with a delayed rate of stature recovery in individuals with mild LBP. This study aimed to explore this association further in a more clinically relevant population of NHS patients with LBP and to investigate if relationships exist with a number of psychological factors. Forty seven patients were recruited from waiting lists for physiotherapist-led rehabilitation programmes. Paraspinal muscle activity while standing was assessed via surface electromyogram (EMG) and stature recovery over a 40-min unloading period was measured on a precision stadiometer. Self-report of pain, disability, anxiety, depression, pain-related anxiety, fear of movement, self-efficacy and catastrophising were recorded. Correlations were found between muscle activity and both pain (r=0.48) and disability (r=0.43). Muscle activity was also correlated with self-efficacy (r=-0.45), depression (r=0.33), anxiety (r=0.31), pain-related anxiety (r=0.29) and catastrophising (r=0.29) and was a mediator between self-efficacy and pain. Pain was a mediator in the relationship between muscle activity and disability. Stature recovery was not found to be related to pain, disability, muscle activity or any of the psychological factors. The findings confirm the importance of muscle activity within LBP, in particular as a pathway by which psychological factors may impact on clinical outcome. The mediating role of muscle activity between psychological factors and pain suggests that interventions that are able to reduce muscle tension may be of particular benefit to patients demonstrating such characteristics, which may help in the targeting of treatment for LBP.

The evolving role of obesity in knee osteoarthritis

PURPOSE OF REVIEW

The frequency of knee osteoarthritis continues to accelerate, likely because of the increasing proliferation of obesity, particularly in men and women 40-60 years of age at the leading edge of the 'baby boom' demographic expansion. The increasing pervasiveness of obesity and the growing appreciation of obesity's accompanying metabolic/inflammatory activities suggest rethinking the knee osteoarthritis paradigm.

RECENT FINDINGS

Whereas once knee osteoarthritis was considered a 'wear-and-tear' condition, it is now recognized that knee osteoarthritis exists in the highly metabolic and inflammatory environments of adiposity. Cytokines associated with adipose tissue, including leptin, adiponectin, and resistin, may influence osteoarthritis though direct joint degradation or control of local inflammatory processes. Further, pound-for-pound, not all obesity is equivalent for the development of knee osteoarthritis; development appears to be strongly related to the co-existence of disordered glucose and lipid metabolism. Additionally, obesity loads may be detected by mechanoreceptors on chondrocyte surfaces triggering intracellular signaling cascades of cytokines, growth factors, and metalloproteinases.

SUMMARY

This review summarizes recent literature about obesity, knee osteoarthritis and joint pain. Consideration of adipocytokines, metabolic factors, and mechanical loading-metabolic factor interactions will help to broaden the thinking about targets for both prevention and intervention for knee osteoarthritis.

Obesity increases the risk of recurrent herniated nucleus pulposus after lumbar microdiscectomy

BACKGROUND CONTEXT

Recurrent herniation of the nucleus pulposus (HNP) frequently causes poor outcomes after lumbar discectomy. The relationship between obesity and recurrent HNP has not previously been reported.

PURPOSE

The purpose of this study was to investigate the association of obesity with recurrent HNP after lumbar microdiscectomy.

STUDY DESIGN

Retrospective Cohort.

PATIENT SAMPLE

We reviewed all cases of one- or two-level lumbar microdiscectomy from L2-S1 performed by a single surgeon with a minimum follow-up of 6 months.

OUTCOME MEASURES

The primary clinical outcomes were evidence of recurrent HNP on magnetic resonance imaging (MRI) and need for repeat surgery.

METHODS

All patients with recurrent radicular pain or new neurological deficits underwent a postoperative MRI scan. Recurrent HNP was defined as a HNP at the same side and same level as the index procedure.

RESULTS

Seventy-five patients were included in the study. The average body mass index (BMI) was 27.6+/-4.6. Thirty-two patients received an MRI scan. The time from operation to repeat MRI scan varied widely (3 days to 15 months). Eight patients (10.7%) had recurrent HNP. Four patients had persistent symptoms requiring reoperation (5.3%). The mean BMI of patients with recurrent HNP was significantly higher than that of those without recurrence (33.6+/-5.1 vs. 26.9+/-3.9, p<.001). In univariate analysis, obese patients (BMI >or=30) were 12 times more likely to have recurrent HNP than nonobese patients (odds ratio [OR]: 12.46, 95% confidence interval [CI]: 2.25-69.90). Obese patients were 30 times more likely to require reoperation (OR: 32.81, 95% CI: 1.67-642.70). Age, sex, smoking, and being a manual laborer were not significantly associated with recurrent HNP. A logistic regression analysis supported the findings of the univariate analysis. In a survival analysis using a Cox proportional hazards model, the hazard ratio of recurrent HNP for obese patients was 17 (OR: 17.08, 95% CI: 2.85-102.30, p=.002).

CONCLUSIONS

Obesity was a strong and independent predictor of recurrent HNP after lumbar microdiscectomy. Surgeons should incorporate weight loss counseling into their preoperative discussions with patients.

Stature recovery after sitting on land and in water

Back pain treatment in water has been commonly used although there is little evidence about its effects. One purported advantage for exercise is the reduced loading due to the buoyant force. The purpose of this study was to compare stature change, as a marker of spinal loading, after sitting in aquatic and dry land environments. Fourteen asymptomatic volunteers had their stature measured in a precision stadiometer, before and after a bout of physical activity and during a recovery period either sitting in water (head out of water immersion; HOWI) and sitting in a chair on land (SITT). Stature loss following exercise was as expected similar in both groups (SITT=89.2+/-5.4% and HOWI=86.5+/-8.1%; p=0.33). When stature recovery was compared between the water and land environments, HOWI (102.2+/-8.7%) showed greater recovery than SITT (86.5+/-6.3%) after 30 min (p<0.05). These results suggest that HOWI facilitated more rapid stature recovery through lower spinal loading and supports use of this technique to reduce spinal loading during recovery.

Gender differences in ground reaction force following perturbations in subjects with low back pain

The purpose of this cross-sectional study was to investigate whether gender differences exist in postural reaction when examining response time and amplitude of normalized ground reaction force (GRF) in subjects with low back pain (LBP). Alterations in GRF following sudden perturbations have led to an increased awareness of the postural compensatory mechanism. Although no specific perturbations have been shown to elicit gender differences, GRF can indirectly measure body sway increases more in subjects with LBP. Eighteen male and eighteen female subjects with LBP participated in this study. Subjects were exposed to sudden perturbations (unexpected and expected) by dropping a weighted ball onto a hand-held pan while subjects stood on the force plate. The amplitude of the normalized GRF and response time were calculated from the instance of perturbation to the first peak of the GRF response measured at the force plate. For the female subjects, the amplitude of the normalized GRF significantly decreased during expected perturbations (F(1,33)=4.23, p<0.04). However, the amplitude for the male subjects did not change during either type of perturbation. The response time was not significantly different between genders (F(1,33)=0.25, p=0.61). The male subjects were better able to stabilize their postural stability after an unexpected perturbation, which reveals postural integrity of compensatory mechanisms. These results indicated that gender differences exist when examining the amplitude of the normalized GRF following sudden perturbations for subjects with LBP.

Using "spinal shrinkage" as a trigger for motivating students to learn about obesity and adopt a healthy lifestyle

Obesity is a global problem; however, relatively little attention is directed toward preparing and inspiring students of medicine and allied medical sciences to address this serious matter. Students are not routinely exposed to the assessment methods for obesity, its overall prevalence, causative factors, short- and long-term consequences, and its management by lifestyle modification. This physiology laboratory exercise involving students of medicine (n = 106) was developed to 1) introduce medical students to methods of obesity assessment and to differentiate between general and abdominal obesity, 2) generate an interest and sensitivity about obesity, and 3) stimulate thinking about modification of their lifestyle in relation to eating habits, weight control, and physical activity. Spinal shrinkage (the difference between the standing height of a person and his/her recumbent length) was used as an immediate observable parameter to demonstrate the effect of adiposity. Spinal shrinkage is recognized as an index of the compressive forces acting on the spine and is related to body mass index. A positive correlation (r = 0.365, P < 0.05) was observed between body mass index and spinal shrinkage. A questionnaire was used to assess student responses to this exercise. Students were motivated to engage in more physical activity (74%), adopt healthier eating (63%), and enhance their knowledge about obesity (67%). They expressed keen interest in the laboratory exercise and found the sessions enjoyable (91%). The laboratory exercise proved to be a success in motivating the students to actively learn and inquire about obesity and to adopt a healthier lifestyle.

Under-arm partial body weight unloading causes spinal elongation and vibration attenuation during treadmill walking

Whilst exercise is beneficial to those suffering from low back pain (LBP), spinal shrinkage and vibration during walking may aggravate the condition. This study investigates the effects of spinal unloading, by means of body-weight unloading (BWU), on spinal length and vibration response. Under-arm partial BWU (40% of bodyweight) was performed on 8 healthy males whilst walking on a treadmill for 1h, and compared to a control condition in the same participants. Motion analysis was used to track four reflective markers attached to the spine between C7 and the lumbar concavity at 100Hz, in 7s samples at regular intervals during the walk. A quintic polynomial was fitted to the coordinates in the sagittal plane, and sub-sectioned into three regions: the upper thoracic (UT), lower thoracic (LT) and upper lumbar (UL). The lengths of the curves were analysed in the time and frequency domains. The length of the spine increased by 4+/-2% (18mm) during the unloading condition with all regions showing an increase in length. The UL and LT regions lost length in the control condition, thereby exhibiting a significant interaction between unloading and time on region length (both P<0.05). In addition, compared to the control condition, the frequencies of the length changes were attenuated between 3 and 6Hz with unloading. Therefore, under-arm BWU facilitates spinal elongation, attenuates the frequency response of the spine in its resonant frequency regime and thus has potential benefits to the LBP population.

Muscle force and force control after weight loss in obese and morbidly obese men

BACKGROUND

Decrease in fat mass and fat-free mass have been observed with weight loss induced by a dietary intervention or surgery. There are concerns that fat-free mass decrease could have some negative functional consequences. The aim of this study was to examine how weight loss affects strength and force control in obese and morbidly obese men.

METHODS

Weight loss was obtained in obese individuals by a hypocaloric diet program until resistance to lose fat and in morbidly obese individuals by bariatric surgery. Maximal force was measured for upper and lower limb and the ability to maintain 15% and 40% of that force. These measures were taken at baseline, in those dieting once resistant to weight loss and 1 year after surgery for those operated on. Normal weight individuals used for control were evaluated twice (6 to 12 months apart).

RESULTS

At baseline, there was no significant difference between groups for maximal forces and capabilities to maintain force levels. Weight loss averaged 11.1% of the initial body weight after dieting and 46.3% 1 year after surgery. At the same time, there was for the lower limb a loss of 10.1% in maximal force after dieting and 33.5% after surgery. For the upper limb, there was no change in maximal force after dieting whereas a decrease of 14.4% was observed after surgery. When transformed in force related to body weight, there was no change in relative force for the lower limb after dieting whereas an increased relative force after surgery. There was no significant difference for the ability for maintaining force levels.

CONCLUSION

Despite a large force loss, particularly for the lower limbs in morbidly obese individuals after surgery, this loss is relatively well tolerated because the relation between force and body weight is even improved and the ability to maintain that force is preserved.

Body weight is a strong predictor of postural stability

Proper balance control is a key aspect of acitivities of daily living. The aim of this study was to determine the contribution of body weight to predict balance stability. The balance stability of 59 male subjects with BMI ranging from 17.4 to 63.8kg/m(2) was assessed using a force platform. The subjects were tested with and without vision. A stepwise multiple regression analysis was used to determine the independent effect of body weight, age, body height and foot length on balance stability (i.e., mean speed of the center of foot pressure). With vision, the stepwise multiple regression revealed that body weight accounted for 52% of the variance of balance stability. The addition of age contributed a further 3% to explain balance control. Without vision, body weight accounted for 54% of the variance and the addition of age and body height added a further 8% and 1% to explain the total variance, respectively. The final model explained 63% of the variance. A decrease in balance stability is strongly correlated to an increase in body weight. This suggests that body weight may be an important risk factor for falling. Future studies should examine more closely the combined effect of aging and obesity on falling and injuries and the impact of obesity on the diverse range of activities of daily living.

Influence of obesity on accurate and rapid arm movement performed from a standing posture

INTRODUCTION

Obesity yields a decreased postural stability. The potentially negative impact of obesity on the control of upper limb movements, however, has not been documented. This study sought to examine if obesity imposes an additional balance control constraint limiting the speed and accuracy with which an upper limb goal-directed movement performed from an upright standing position can be executed.

METHOD

Eight healthy lean subjects (body mass index (BMI) between 20.9 and 25.0 kg/m(2)) and nine healthy obese subjects (BMI between 30.5 and 48.6 kg/m(2)) pointed to a target located in front of them from an upright standing posture. The task was to aim at the target as fast and as precisely as possible after an auditory signal. The difficulty of the task was varied by using different target sizes (0.5, 1.0, 2.5 and 5.0 cm width). Hand movement time (MT) and velocity profiles were measured to quantify the aiming. Centre of pressure and segmental kinematics were analysed to document postural stability.

RESULTS

When aiming, the forward centre of pressure (CP) displacement was greater for the obese group than for the normal BMI group (4.6 and 1.9 cm, respectively). For the obese group, a decrease in the target size was associated with an increase in backward CP displacement and CP peak speed whereas for the normal BMI group backward CP displacements and CP peak speed were about the same across all target sizes. Obese participants aimed at the target moving their whole body forward whereas the normal BMI subjects predominantly made an elbow extension and shoulder flexion. For both groups, MT increased with a decreasing target size. Compare to the normal BMI group, this effect was exacerbated for the obese group. For the two smallest targets, movements were on average 115 and 145 ms slower for the obese than for the normal BMI group suggesting that obesity added a balance constraint and limited the speed with which an accurate movement could be done.

SUMMARY

Obesity, because of its effects on the control of balance, also imposes constraints on goal-directed movements. From a clinical perspective, obese individuals might be less efficient and more at risk of injuries than normal weight individuals in a large number of work tasks and daily activities requiring upper limb movements performed from an upright standing position.