Discovery of [11C]MK-6884: A Positron Emission Tomography (PET) Imaging Agent for the Study of M4Muscarinic Receptor Positive Allosteric Modulators (PAMs) in Neurodegenerative Diseases

The measurement of receptor occupancy (RO) using positron emission tomography (PET) has been instrumental in guiding discovery and development of CNS directed therapeutics. We and others have investigated muscarinic acetylcholine receptor 4 (M4) positive allosteric modulators (PAMs) for the treatment of symptoms associated with neuropsychiatric disorders. In this article, we describe the synthesis, in vitro, and in vivo characterization of a series of central pyridine-related M4 PAMs that can be conveniently radiolabeled with carbon-11 as PET tracers for the in vivo imaging of an allosteric binding site of the M4 receptor. We first demonstrated its feasibility by mapping the receptor distribution in mouse brain and confirming that a lead molecule 1 binds selectively to the receptor only in the presence of the orthosteric agonist carbachol. Through a competitive binding affinity assay and a number of physiochemical properties filters, several related compounds were identified as candidates for in vivo evaluation. These candidates were then radiolabeled with ¹¹C and studied in vivo in rhesus monkeys. This research eventually led to the discovery of the clinical radiotracer candidate [¹¹C]MK-6884.

Is chronic ankle instability associated with impaired muscle strength? Ankle, knee and hip muscle strength in individuals with chronic ankle instability: a systematic review with meta-analysis

OBJECTIVE

Determine whether impairments in lower limb muscle strength exist in individuals with chronic ankle instability (CAI) compared with uninjured controls.

DESIGN

Systematic review with meta-analysis.

DATA SOURCE

A comprehensive search of PubMed, Cochrane, CINAHL, Web of Science and EMBASE electronic databases from inception to 10 February 2019.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

Cross-sectional and case-control studies were included if they objectively measured lower limb muscle strength in individuals with CAI compared with controls. Risk of bias and quality of included studies were assessed. Data of included studies were extracted, and meta-analysis was conducted where appropriate.

RESULTS

12 397 unique studies were identified, of which 20 were included and 16 were eligible for meta-analysis. Reviewed studies clearly described the aim/hypothesis and main outcome measure, but most lacked sample size calculation and assessor blinding. Meta-analyses showed individuals with CAI had lower eccentric and concentric evertor strength (30 and 120°/s; Nm; standardised mean difference (SMD) between -0.73 and -0.95), eccentric invertor strength (60 and 120°/s; both Nm and Nm/kg; SMD between -0.61 and -1.37), concentric invertor strength (60 and 120°/s; Nm; SMD=-0.7) and concentric knee extensor strength (SMD=-0.64) compared with control participants. Ankle eccentric dorsiflexor strength was not different between groups. Although pooling was not possible, data from three separate studies indicated that hip flexor, abductor and external rotator strength, but not hip adductor and extensor strength, was lower in individuals with CAI than in control participants.

CONCLUSION

Individuals with CAI have ankle inversion and eversion strength deficits. Our data also point to differences between individuals with CAI and controls in hip and knee strength. These elements of the kinetic chain should be evaluated by clinicians who rehabilitate individuals with CAI.

PROSPERO REGISTRATION NUMBER

CRD42016037759.

Effects of the MY34/2018 Global Dust Storm as Measured by MSL REMS in Gale Crater

The Rover Environmental Monitoring Station (REMS) instrument that is onboard NASA's Mars Science Laboratory (MSL) Curiosity rover. REMS has been measuring surface pressure, air and ground brightness temperature, relative humidity, and UV irradiance since MSL's landing in 2012. In Mars Year (MY) 34 (2018) a global dust storm reached Gale Crater at L_s ~190°. REMS offers a unique opportunity to better understand the impact of a global dust storm on local environmental conditions, which complements previous observations by the Viking landers and Mars Exploration Rovers. All atmospheric variables measured by REMS are strongly affected albeit at different times. During the onset phase, the daily maximum UV radiation decreased by 90% between sols 2075 (opacity ~1) and 2085 (opacity ~8.5). The diurnal range in ground and air temperatures decreased by 35K and 56K, respectively, with also a diurnal-average decrease of ~2K and 4K respectively. The maximum relative humidity, which occurs right before sunrise, decreased to below 5%, compared with pre-storm values of up to 29%, due to the warmer air temperatures at night while the inferred water vapor abundance suggests an increase during the storm. Between sols 2085 and 2130, the typical nighttime stable inversion layer was absent near the surface as ground temperatures remained warmer than near-surface air temperatures. Finally, the frequency-domain behavior of the diurnal pressure cycle shows a strong increase in the strength of the semidiurnal and terdiurnal modes peaking after the local opacity maximum, also suggesting differences in the dust abundance inside and outside Gale.

Feasibility and impact of sit-stand workstations with and without exercise in office workers at risk of low back pain: A pilot comparative effectiveness trial

The aim of this study was to compare the feasibility and impact of sit-stand workstations plus advice, with or without exercise, on back pain and sitting time in office workers at risk of low back pain (LBP). Eligible participants (n = 29/169; 17% overall) were randomized to receive a sit-stand workstation and advice with (n = 16) or without (n = 13) progressive resistance exercise training for 4-weeks. Feasibility (recruitment, acceptability, adherence) and impact (LBP severity during a standardized standing task, workplace-sitting time) were assessed. Intervention acceptability (87.5% very satisfied) was good and adherence (60% completed all 12 exercise sessions) was satisfactory. Maximum LBP severity (mean difference of -1.3 (-2.0, -0.6) and workplace sitting time (82.7-99.3 min/8-hr workday reduction) were similarly reduced in both groups. The introduction of a sit-stand workstation with advice was feasible and achieved similar outcomes for LBP and workplace sitting time when administered with or without exercise.

Exercise for posterior tibial tendon dysfunction: a systematic review of randomised clinical trials and clinical guidelines

Objective

To systematically review all randomised clinical trials to determine the efficacy of local strengthening exercises compared with other forms of conservative management for adults with posterior tibial tendon dysfunction.

Design

Systematic review.

Data sources

Four electronic databases (Cumulative Index to Nursing and Allied Health Literature, Cochrane, Embase and PubMed) were searched up to June 2018.

Eligibility criteria for selecting studies

The study included randomised clinical trials investigating individuals with posterior tibial tendon dysfunction where local strengthening was compared with other forms of conservative management with respect to pain, function and/or physical impairment outcome measures. Standardised mean differences (SMDs) were used to compare change scores between groups and descriptors of exercise prescription assessed according to the Template for Intervention Description and Replication and the Toigo and Boutellier recommendations.

Results

3 studies (n=93) were eligible for inclusion in the review. Varying strengthening exercises were compared with stretching and foot orthoses (n=2) or no intervention (n=1). Moderate effects (SMD 0.6-1.2) were found for reducing pain and disability with eccentric strengthening in conjunction with stretching and orthoses compared with concentric exercises, stretching and orthoses combined, and stretching and orthoses alone. Evaluation of exercise prescription parameters demonstrated minimal reporting, with the only consistent parameters being the number of sets and repetitions of the exercises, and the duration of the experimental period.

Conclusion

This review demonstrates the paucity of high-quality research for the conservative management of posterior tibial tendon dysfunction, and highlights the lack of exercise prescription parameters reported in clinical trials.

Trial registration number

CRD42017076156.

Balance performance in older adults with hip osteoarthritis: A systematic review

BACKGROUND

The hip is one of the most common joints affected by osteoarthritis (OA) and it has been identified as a key risk factors for falls. Physical impairments associated with OA, such as joint pain, muscle weakness, joint stiffness and sensory dysfunction, can all negatively affect balance and increase risk of falling.

QUESTION

Is balance performance altered in older adults with hip osteoarthritis? To determine whether static, dynamic, reactive or functional balance performance is altered in older people with hip osteoarthritis.

METHODS

Quantitative measures of postural control, including clinical and lab-based assessment of static, dynamic, reactive and/or functional balance performance, compared with a healthy control group or to the asymptomatic limb.

RESULTS

A total of 5407 articles were identified and 14 papers were included (10 with standardised mean different (SMD) data, four without SMD data). Based on data from single studies, there were medium/large effects for increased medio-lateral displacement when standing with eyes open, increased anterior-posterior and total sway path length when standing with eyes closed, greater overall instability when standing on an unstable surface, and increased displacement toward the stance leg in a lateral step in hip OA compared with controls.

CONCLUSION

Balance impairments were identified in some measures, limiting the conclusions as to whether balance deficits are a problem in hip OA. Inconsistent findings suggest that balance may not be a primary contributor to increased falls risk in older adults with hip OA. Other factors, such as musculoskeletal deficits, may contribute to higher falls rate in this population.

The experience of persistent pain and quality of life among women following treatment for breast cancer: An attachment perspective

OBJECTIVES

The aims of this study were to investigate associations between attachment and the presence of persistent pain in women following treatment for breast cancer and to investigate the relationship between attachment, pain, and quality of life (QOL) in women with persistent pain.

METHODS

Women (N = 335) previously diagnosed with primary non-metastatic breast cancer completed an online survey with measures of attachment, pain, QOL, demographics, and medical history. Variables were compared between women with (N = 128) and without (N = 207) persistent pain. For those reporting pain, regression analyses were conducted to investigate relationships between attachment, pain, and QOL.

RESULTS

Higher attachment anxiety, but not attachment avoidance, was related to the presence of persistent pain. Among women with persistent pain, associations between attachment anxiety and avoidance and greater pain intensity were lost when pain catastrophizing was considered in analysis. Significant associations between attachment and diminished QOL and perceived effectiveness of pain management were identified in multivariate analysis.

CONCLUSIONS

These findings extend the available literature regarding associations between pain and attachment insecurity. In women with pain after breast cancer treatment, attachment anxiety and avoidance were associated with negative pain and QOL outcomes. Further attention regarding the use of attachment-informed approaches in supporting women following breast cancer treatment is indicated.

Network meta-analysis of surgical management of gastro-oesophageal reflux disease in adults

BACKGROUND

Proton pump inhibitors are the mainstay of treatment for gastro-oesophageal reflux disease, but are associated with ongoing costs and side-effects. Antireflux surgery is cost-effective and is preferred by many patients. A total (360^o or Nissen) fundoplication is the traditional procedure, but other variations including partial fundoplications are also commonly performed, with the aim of achieving durable reflux control with minimal dysphagia. Many RCTs and some pairwise meta-analyses have compared some of these procedures but there is still uncertainty about which, if any, is superior. Network meta-analysis allows multiple simultaneous comparisons and robust synthesis of the available evidence in these situations. A network meta-analysis comparing all antireflux procedures was performed to identify which has the most favourable outcomes at short-term (3-12 months), medium-term (1-5 years) and long-term (10 years and more than 10 years) follow-up.

METHODS

Article databases were searched systematically for all eligible RCTs. Primary outcomes were quality-of-life measures and dysphagia. Secondary outcomes included reflux symptoms, pH studies and complications.

RESULTS

Fifty-one RCTs were included, involving 5357 patients and 14 different treatments. Posterior partial fundoplication ranked best in terms of reflux symptoms, and caused less dysphagia than most other interventions including Nissen fundoplication. This was consistent across all time points and outcome measures.

CONCLUSION

Posterior partial fundoplication provides the best balance of long-term, durable reflux control with less dysphagia, compared with other treatments.

Skill not athleticism predicts individual variation in match performance of soccer players

Just as evolutionary biologists endeavour to link phenotypes to fitness, sport scientists try to identify traits that determine athlete success. Both disciplines would benefit from collaboration, and to illustrate this, we used an analytical approach common to evolutionary biology to isolate the phenotypes that promote success in soccer, a complex activity of humans played in nearly every modern society. Using path analysis, we quantified the relationships among morphology, balance, skill, athleticism and performance of soccer players. We focused on performance in two complex motor activities: a simple game of soccer tennis (1 on 1), and a standard soccer match (11 on 11). In both contests, players with greater skill and balance were more likely to perform better. However, maximal athletic ability was not associated with success in a game. A social network analysis revealed that skill also predicted movement. The relationships between phenotypes and success during individual and team sports have potential implications for how selection acts on these phenotypes, in humans and other species, and thus should ultimately interest evolutionary biologists. Hence, we propose a field of evolutionary sports science that lies at the nexus of evolutionary biology and sports science. This would allow biologists to take advantage of the staggering quantity of data on performance in sporting events to answer evolutionary questions that are more difficult to answer for other species. In return, sports scientists could benefit from the theoretical framework developed to study natural selection in non-human species.

The Vertical Dust Profile over Gale Crater, Mars

We create a vertically coarse, but complete, vertical profile of dust mixing ratio from the surface to the upper atmosphere over Gale Crater, Mars, using the frequent joint atmospheric observations of the orbiting Mars Climate Sounder (MCS) and the Mars Science Laboratory (MSL) Curiosity rover. Using these data and an estimate of planetary boundary layer (PBL) depth from the MarsWRF general circulation model, we divide the vertical column into three regions. The first region is the Gale Crater PBL, the second is the MCS-sampled region, and the third is between these first two. We solve for a well-mixed dust mixing ratio within this third (middle) layer of atmosphere to complete the profile. We identify a unique seasonal cycle of dust within each atmospheric layer. Within the Gale PBL, dust mixing ratio maximizes near southern hemisphere summer solstice (L_s = 270°) and minimizes near winter solstice (L_s = 90-100°) with a smooth sinusoidal transition between them. However, the layer above Gale Crater and below the MCS-sampled region more closely follows the global opacity cycle and has a maximum in opacity near L_s = 240° and exhibits a local minimum (associated with the "solsticial pause" in dust storm activity) near L_s = 270°. With knowledge of the complete vertical dust profile, we can also assess the frequency of high-altitude dust layers over Gale. We determine that 36% of MCS profiles near Gale Crater contain an "absolute" high-altitude dust layer wherein the dust mixing ratio is the maximum in the entire vertical column.

Reported selection criteria for adult acquired flatfoot deformity and posterior tibial tendon dysfunction: Are they one and the same? A systematic review

BACKGROUND

Posterior tibial tendon dysfunction (PTTD) and adult acquired flatfoot deformity (AAFD) are used interchangeably, although both suggest quite different pathological processes.

OBJECTIVE

To investigate key differences in selection criteria used for inclusion into research studies.

METHODS

An electronic database search was performed from inception to June 2016. All primary research articles with clear inclusion/diagnostic criteria for PTTD or AAFD were included in the review. All criteria were extracted and synthesised into one aggregate list. Frequencies of recurring criteria were calculated and reported for each stage of the conditions.

RESULTS

Of the potentially eligible papers, 148 (65%) did not specify inclusion/selection criteria for PTTD or AAFD and were excluded. Eligibility criteria were reported 82 times in the 80 included papers, with 69 descriptions for PTTD and 13 for AAFD. After synthesis of criteria from all papers, there were 18 key signs and symptoms. Signs and symptoms were considered to be those relating to tendon pathology and those relating to structural deformity. The total number of individual inclusion/diagnostic criteria ranged from 2 to 9. The majority of articles required signs of both tendon dysfunction and structural deformity (84% for AAFD and 81% for PTTD). Across both groups, the most frequently reported criteria were abduction of the forefoot (11.5% of total criteria used), the presence of a flexible deformity (10.2%) and difficulty performing a single leg heel raise (10.0%). This was largely the case for the PTTD articles, whereas the AAFD articles were more focused on postural issues such as forefoot abduction, medial arch collapse, and hindfoot valgus (each 16.7%).

CONCLUSION

As well as synthesising the available literature and providing reporting recommendations, this review has identified that many papers investigating PTTD/AAFD do not state condition-specific selection criteria and that this limits their clinical applicability. Key signs and symptoms of PTTD and AAFD appear similar, except in early PTTD where no structural deformity is present. We recommend that PTTD is the preferred terminology for the condition associated with signs of local tendon dysfunction with pain and/or swelling along the tendon and difficulty with inversion and/or single leg heel raise characterising stage I and difficulty with single leg heel raise and a flexible flatfoot deformity characterizing stage II PTTD. While AAFD may be useful as an umbrella term for acquired flatfoot deformities, the specific associated aetiology should be reported in studies to aid consolidation and implementation of research into practice.

TRIAL REGISTRATION

Prospero ID: 42016046943.

Composite infrared spectrometer (CIRS) on Cassini: publisher's note

This publisher's note renumbers the reference list in Appl. Opt.56, 5274 (2017)APOPAI0003-693510.1364/AO.56.005274.

Composite infrared spectrometer (CIRS) on Cassini

The Cassini spacecraft orbiting Saturn carries the composite infrared spectrometer (CIRS) designed to study thermal emission from Saturn and its rings and moons. CIRS, a Fourier transform spectrometer, is an indispensable part of the payload providing unique measurements and important synergies with the other instruments. It takes full advantage of Cassini's 13-year-long mission and surpasses the capabilities of previous spectrometers on Voyager 1 and 2. The instrument, consisting of two interferometers sharing a telescope and a scan mechanism, covers over a factor of 100 in wavelength in the mid and far infrared. It is used to study temperature, composition, structure, and dynamics of the atmospheres of Jupiter, Saturn, and Titan, the rings of Saturn, and surfaces of the icy moons. CIRS has returned a large volume of scientific results, the culmination of over 30 years of instrument development, operation, data calibration, and analysis. As Cassini and CIRS reach the end of their mission in 2017, we expect that archived spectra will be used by scientists for many years to come.

High-Throughput Agonist Shift Assay Development for the Analysis of M1-Positive Allosteric Modulators

Agonist shift assays feature cross-titrations of allosteric modulators and orthosteric ligands. Information generated in agonist shift assays can include a modulator's effect on the orthosteric agonist's potency (alpha) and efficacy (beta), as well as direct agonist activity of the allosteric ligand (tauB) and the intrinsic binding affinity of the modulator to the unoccupied receptor (KB). Because of the heavy resource demand and complex data handling, these allosteric parameters are determined infrequently during the course of a drug discovery program and on a relatively small subset of compounds. Automation of agonist shift assays enables this data-rich analysis to evaluate a larger number of compounds, offering the potential to differentiate compound classes earlier and prospectively prioritize based on desired molecular pharmacology. A high-throughput calcium-imaging agonist shift assay was pursued to determine the allosteric parameters of over 1000 positive allosteric modulator (PAM) molecules for the human muscarinic acetylcholine receptor 1 (M₁). Control compounds were run repeatedly to demonstrate internal consistency. Comparisons between potency measurements and the allosteric parameter results demonstrate that these different types of measurements do not necessarily correlate, highlighting the importance of fully characterizing and understanding the allosteric properties of leads.

Network meta-analysis of the effect of preoperative carbohydrate loading on recovery after elective surgery

BACKGROUND

Three meta-analyses have summarized the effects of preoperative carbohydrate administration on postoperative outcomes in adult patients undergoing elective surgery. However, these studies could not account for the different doses of carbohydrate administered and the different controls used. Multiple-treatments meta-analysis allows robust synthesis of all available evidence in these situations.

METHODS

Article databases were searched systematically for RCTs comparing preoperative carbohydrate administration with water, a placebo drink, or fasting. A four-treatment multiple-treatments meta-analysis was performed comparing two carbohydrate dose groups (low, 10-44 g; high, 45 g or more) with two control groups (fasting; water or placebo). Primary outcomes were length of hospital stay and postoperative complication rate. Secondary outcomes included postoperative insulin resistance, vomiting and fatigue.

RESULTS

Some 43 trials involving 3110 participants were included. Compared with fasting, preoperative low-dose and high-dose carbohydrate administration decreased postoperative length of stay by 0·4 (95 per cent c.i. 0·03 to 0·7) and 0·2 (0·04 to 0·4) days respectively. There was no significant decrease in length of stay compared with water or placebo. There was no statistically significant difference in the postoperative complication rate, or in most of the secondary outcomes, between carbohydrate and control groups.

CONCLUSION

Carbohydrate loading before elective surgery conferred a small reduction in length of postoperative hospital stay compared with fasting, and no benefit in comparison with water or placebo.

Photosynthetic responses of a dominant C4 grass to an experimental heat wave are mediated by soil moisture

Extreme heat waves and drought are predicted to increase in frequency and magnitude with climate change. These extreme events often co-occur, making it difficult to separate their direct and indirect effects on important ecophysiological and carbon cycling processes such as photosynthesis. Here, we assessed the independent and interactive effects of experimental heat waves and drought on photosynthesis in Andropogon gerardii, a dominant C₄ grass in a native mesic grassland. We experimentally imposed a two-week heat wave at four intensity levels under two contrasting soil moisture regimes: a well-watered control and an extreme drought. There were three main findings from this study. First, the soil moisture regimes had large effects on canopy temperature, leading to extremely high temperatures under drought and low temperatures under well-watered conditions. Second, soil moisture mediated the photosynthetic response to heat; heat reduced photosynthesis under the well-watered control, but not under the extreme drought treatment. Third, the effects of heat on photosynthesis appeared to be driven by a direct thermal effect, not indirectly through other environmental or ecophysiological variables. These results suggest that while photosynthesis in this dominant C₄ grass is sensitive to heat stress, this sensitivity can be overwhelmed by extreme drought stress.

Non-surgical treatment of hallux valgus: a current practice survey of Australian podiatrists

Background

Patients with hallux valgus (HV) frequently present to podiatrists for non-surgical management, with a wide range of concerns including pain, footwear difficulty and quality of life impacts. There is little research evidence guiding podiatrists’ clinical decisions surrounding non-surgical management of HV. Thus practitioners rely largely upon clinical experience and expert opinion. This survey was conducted to determine whether a consensus exists among Australian podiatrists regarding non-surgical treatment of HV, and secondly to explore common presenting concerns and physical examination findings associated with HV.

Methods

An online survey was distributed to Australian podiatrists in mid-2013 via the professional association in each state (approximately 1900 members). Podiatrists indicated common treatments recommended, presenting problems and physical examination findings associated with HV in juveniles, adults and older adults. Proportions were calculated to determine the most common responses, and Chi-squared tests were used to examine differences in treatment recommendations according to HV patient age group and podiatrist demographics.

Results

Of 210 survey respondents, 65 % (136) were female and 80 % (168) were private practitioners. Complete survey responses were received from 159 podiatrists for juvenile HV, 146 for adults and 141 for older adults. Seven different non-surgical treatment options were commonly recommended (by >50 % podiatrists), although recommendations differed between adult, older adult and juvenile HV. Common treatments included footwear advice or modification, custom and prefabricated orthotic devices, addition of padding, and muscle strengthening/retraining exercises. Padding was more likely to be utilised in older adults, while exercises were more likely to be prescribed for juveniles. A diverse range of presenting problems and physical examination findings were reported to be associated with HV.

Conclusions

Despite the lack of empirical evidence in this area, there appears to be a consensus among Australian podiatrists regarding non-surgical management of HV, and these recommendations are largely aligned with available clinical consensus documents. Presenting concerns and physical examination findings associated with HV are diverse and have implications for treatment decisions. Management strategies differ across patient age groups, thus any updated clinical guidelines should differentiate between adult and juvenile HV. This study provides useful data to inform clinical practice, education, policy and future research.

Electronic supplementary material

The online version of this article (doi:10.1186/s13047-016-0146-5) contains supplementary material, which is available to authorized users.

Inequalities in long term health-related quality of life between partnered and not partnered breast cancer survivors through the mediation effect of social support

OBJECTIVE

To compare long-term quality of life outcomes by marital status among women living with breast cancer, and to test the mediation effects of social support as an underlying factor.

METHODS

Data are drawn from 1996 to 2010 of the Australian Longitudinal Study on Women's Health. The sample included 505 women with breast cancer with six years of follow-up data. Social support was measured by the Medical Outcomes Study Social Support Survey (MOS-SSS). Physical and mental health-related quality of life (HRQOL) was measured using the Short-Form Health Survey (SF-36).

RESULTS

Breast cancer survivors who did not have a partner, compared to those who had a partner, had significantly lower levels of social support, which was associated with poorer HRQOL. Social support mediated the relationship between not having a partner and poorer HRQOL. Results were consistent after taken into consideration socio-demographic characteristics, which included age, highest level of education, country of birth, and area of residence.

CONCLUSIONS

Women recovering from breast cancer who do not have partners have poorer physical and mental HRQOL, than those with partners, with a lack of social support as an underlying inequality. Partners of breast cancer survivors are importance sources in the provision of social support to help them maintain well-being and quality of life. Copyright © 2016 John Wiley & Sons, Ltd.

Out-Patient Pulmonary Rehabilitation Improves Medial-Lateral Balance in Subjects With Chronic Respiratory Disease: Proof-of-Concept Study

BACKGROUND

Recent studies show balance impairment in subjects with chronic respiratory disease. The aim of this proof-of-concept study was to investigate clinical and quantitative measures of balance in people with chronic respiratory disease following participation in an out-patient pulmonary rehabilitation (PR) program to better understand features of balance improvement. A secondary aim was to probe possible mechanisms for balance improvement to provide the foundation for optimal design of future studies.

METHODS

Eleven individuals with chronic respiratory disease enrolled in an 8-week out-patient PR program participated. Standing balance, measured with a force plate, in the medial-lateral and anterior-posterior directions with eyes open and closed was assessed with linear (SD and sway path length) and non-linear (diffusion analysis) center-of-pressure measures. Balance was evaluated clinically with the Timed Up and Go and Four Square Step Test. Fear of falling and balance confidence were assessed with questionnaires.

RESULTS

After participation in PR, medial-lateral sway path length decreased (P = .031), and center-of-pressure diffusion in the medial-lateral direction was slower (P = .02) and traveled over less distance (P = .03) with eyes closed. This suggests greater control of medial-lateral sway. There was no change in anterior-posterior balance (P > .067). Performance improved on the Timed Up and Go (median [interquartile range] pre-PR = 9.4 [7.9-12.8] vs. post-PR = 8.1 [7.3-12.2] s, P = .003) and Four Square Step Test (median [interquartile range] pre-PR = 9.3 [7.2-14.2] vs. post-PR = 8.7 [7.4-10.2] s, P = .050). There were no changes in balance confidence (P = .72) or fear of falling (P = .57).

CONCLUSIONS

Participation in an 8-week out-patient PR program improved balance, as assessed by clinical and laboratory measures. Detailed analysis of force plate measures demonstrated improvements primarily with respect to medial-lateral balance control. These data provide a basis for the development of larger scale studies to investigate the mechanisms for medial-lateral balance improvements following PR and to determine how PR may be refined to enhance balance outcomes in this population. (ClinicalTrials.gov registration NCT00864084.).

Balance recovery is compromised and trunk muscle activity is increased in chronic obstructive pulmonary disease

Increased respiration in chronic obstructive pulmonary disease (COPD) requires greater abdominal muscle activation, which may impact on contribution of the trunk to postural control. This study aimed to determine whether recovery of balance from postural perturbations and trunk muscle activity differs in people with and without COPD before and/or after exercise. Electromyography (EMG) of the obliquus internus (OI) and externus (OE) abdominis, rectus abdominis (RA), erector spinae (ES) and deltoid muscles was recorded with surface electrodes during rapid shoulder flexion and extension. Time taken to regain baseline centre of pressure velocity (vCOP) and the number of postural adjustments following arm movement was calculated from force plate data. Time to recover balance in the direction of postural disturbance (anteroposterior vCOP) was longer in COPD, particularly more severe COPD, than controls. Mediolateral vCOP (perpendicular to the perturbation) and the number of postural adjustments did not differ between groups, but people with more severe COPD were less successful at returning their mediolateral vCOP to baseline. Abdominal muscle EMG was similar between groups, but controls had greater ES EMG during arm movements. Individuals with more severe COPD had greater OE and RA EMG both before and during arm movement compared to those with less severe COPD and controls. Following exercise, OE and ES EMG increased in people with less severe COPD. This study shows that severe COPD is associated with impaired ability to recover balance and greater trunk muscle activity during postural challenges. Augmented trunk muscle activity may limit the contribution of trunk movements to balance recovery and could contribute to increased falls risk.