Responsible research practices could be more strongly endorsed by Australian university codes of research conduct.

BACKGROUND: This study aimed to investigate how strongly Australian university codes of research conduct endorse responsible research practices. METHODS: Codes of research conduct from 25 Australian universities active in health and medical research were obtained from public websites, and audited against 19 questions to assess how strongly they (1) defined research integrity, research quality, and research misconduct, (2) required research to be approved by an appropriate ethics committee, (3) endorsed 9 responsible research practices, and (4) discouraged 5 questionable research practices. RESULTS: Overall, a median of 10 (IQR 9 to 12) of 19 practices covered in the questions were mentioned, weakly endorsed, or strongly endorsed. Five to 8 of 9 responsible research practices were mentioned, weakly, or strongly endorsed, and 3 questionable research practices were discouraged. Results are stratified by Group of Eight (n = 8) and other (n = 17) universities. Specifically, (1) 6 (75%) Group of Eight and 11 (65%) other codes of research conduct defined research integrity, 4 (50%) and 8 (47%) defined research quality, and 7 (88%) and 16 (94%) defined research misconduct. (2) All codes required ethics approval for human and animal research. (3) All codes required conflicts of interest to be declared, but there was variability in how strongly other research practices were endorsed. The most commonly endorsed practices were ensuring researcher training in research integrity [8 (100%) and 16 (94%)] and making study data publicly available [6 (75%) and 12 (71%)]. The least commonly endorsed practices were making analysis code publicly available [0 (0%) and 0 (0%)] and registering analysis protocols [0 (0%) and 1 (6%)]. (4) Most codes discouraged fabricating data [5 (63%) and 15 (88%)], selectively deleting or modifying data [5 (63%) and 15 (88%)], and selective reporting of results [3 (38%) and 15 (88%)]. No codes discouraged p-hacking or hypothesising after results are known. CONCLUSIONS: Responsible research practices could be more strongly endorsed by Australian university codes of research conduct. Our findings may not be generalisable to smaller universities, or those not active in health and medical research.

Encouraging responsible reporting practices in the Instructions to Authors of neuroscience and physiology journals: There is room to improve.

Journals can substantially influence the quality of research reports by including responsible reporting practices in their Instructions to Authors. We assessed the extent to which 100 journals in neuroscience and physiology required authors to report methods and results in a rigorous and transparent way. For each journal, Instructions to Authors and any referenced reporting guideline or checklist were downloaded from journal websites. Twenty-two questions were developed to assess how journal Instructions to Authors address fundamental aspects of rigor and transparency in five key reporting areas. Journal Instructions to Authors and all referenced external guidelines and checklists were audited against these 22 questions. Of the full sample of 100 Instructions to Authors, 34 did not reference any external reporting guideline or checklist. Reporting whether clinical trial protocols were pre-registered was required by 49 journals and encouraged by 7 others. Making data publicly available was encouraged by 64 journals; making (processing or statistical) code publicly available was encouraged by ∼30 of the journals. Other responsible reporting practices were mentioned by less than 20 of the journals. Journals can improve the quality of research reports by mandating, or at least encouraging, the responsible reporting practices highlighted here.

Upper Limb Function but Not Proprioception is Impaired in Essential Tremor: A Between-Groups Study and Causal Mediation Analysis.

Background: Essential tremor (ET) is characterized by abnormal oscillatory muscle activity and cerebellar involvement, factors that can lead to proprioceptive deficits, especially in active tasks. The present study aimed to quantify the severity of proprioceptive deficits in people with ET and estimate how these contribute to functional impairments. Methods: Upper limb sensory, proprioceptive and motor function was assessed inindividuals with ET (n = 20) and healthy individuals (n = 22). To measure proprioceptive ability, participants discriminated the width of grasped objects and the weight of objects liftedwith the wrist extensors. Causal mediation analysis was used to estimate the extentthat impairments in upper limb function in ET was mediated by proprioceptive ability. Results: Participants with ET had impaired upper limb function in all outcomes, and had greater postural and kinetic tremor. There were no differences between groups in proprioceptive discrimination of width (between-group mean difference [95% CI]: 0.32 mm [-0.23 to 0.87 mm]) or weight (-1.12 g [-7.31 to 5.07 g]). Causal mediation analysis showed the effect of ET on upper limb function was not mediated by proprioceptive ability. Conclusions: Upper limb function but not proprioception was impaired in ET. The effect of ET on motor function was not mediated by proprioception. These results indicate that the central nervous system of people with ET is able to accommodate mild to moderate tremor in active proprioceptive tasks that rely primarily on afferent signals from muscle spindles.

The effect of face-to-face versus online learning on student performance in anatomy: an observational study using a causal inference approach.

Introduction: This study aimed to estimate the causal effect of face-to-face learning on student performance in anatomy, compared to online learning, by analysing examination marks under a causal structure. Methods: We specified a causal graph to indicate how the mode of learning affected student performance. We sampled purposively to obtain end-semester examination marks of undergraduate and postgraduate students who learned using face-to-face (pre-COVID, 2019) or online modes (post-COVID, 2020). The analysis was informed by the causal graph. Marks were compared using linear regression, and sensitivity analyses were conducted to assess if effects were robust to unmeasured confounding. Results: On average, face-to-face learning improved student performance in the end-semester examination in undergraduate students (gain of mean 8.3%, 95% CI 3.3 to 13.4%; E-value 2.77, lower limit of 95% CI 1.80) but lowered performance in postgraduate students (loss of 8.1%, 95% CI 3.6 to 12.6%; E-value 2.89, lower limit of 95% CI 1.88), compared to online learning. Discussion: Under the assumed causal graph, we found that compared to online learning, face-to-face learning improved student performance in the end-semester examination in undergraduate students, but worsened student performance in postgraduate students. These findings suggest that different modes of learning may suit different types of students. Importantly, this is the first attempt to estimate causal effects of the mode of learning on student performance under a causal structure. This approach makes our assumptions transparent, informs data analysis, and is recommended when using observational data to make causal inferences.

Poor statistical reporting, inadequate data presentation and spin persist despite Journal awareness and updated Information for Authors.

Sound reporting of research results is fundamental to good science. Unfortunately, poor reporting is common and does not improve with editorial educational strategies. We investigated whether publicly highlighting poor reporting at a journal can lead to improved reporting practices. We also investigated whether reporting practices that are required or strongly encouraged in journal Information for Authors are enforced by journal editors and staff. A 2016 audit highlighted poor reporting practices in the Journal of Neurophysiology. In August 2016 and 2018, the American Physiological Society updated the Information for Authors, which included the introduction of several required or strongly encouraged reporting practices. We audited Journal of Neurophysiology papers published in 2019 and 2020 (downloaded through the library of the University of New South Wales) on reporting items selected from the 2016 audit, the newly introduced reporting practices, and items from previous audits. Summary statistics (means, counts) were used to summarize audit results. In total, 580 papers were audited. Compared to results from the 2016 audit, several reporting practices remained unchanged or worsened. For example, 60% of papers erroneously reported standard errors of the mean, 23% of papers included undefined measures of variability, 40% of papers failed to define a statistical threshold for their tests, and when present, 64% of papers with p-values between 0.05 and 0.1 misinterpreted them as statistical trends. As for the newly introduced reporting practices, required practices were consistently adhered to by 34 to 37% of papers, while strongly encouraged practices were consistently adhered to by 9 to 26% of papers. Adherence to the other audited reporting practices was comparable to our previous audits. Publicly highlighting poor reporting practices did little to improve research reporting. Similarly, requiring or strongly encouraging reporting practices was only partly effective. Although the present audit focused on a single journal, this is likely not an isolated case. Stronger, more strategic measures are required to improve poor research reporting.

Muscle electromyographic activity normalized to maximal muscle activity, not to Mmax, better represents voluntary activation.

In human applied physiology studies, the amplitude of recorded muscle electromyographic activity (EMG) is often normalized to maximal EMG recorded during a maximal voluntary contraction. When maximal contractions cannot be reliably obtained (e.g. in people with muscle paralysis, anterior cruciate ligament injury, or arthritis), EMG is sometimes normalized to the maximal compound muscle action potiential evoked by stimulation, the Mmax. However, it is not known how these two methods of normalization affect the conclusions and comparability of studies. To address this limitation, we investigated the relationship between voluntary muscle activation and EMG normalized either to maximal EMG or to Mmax. Twenty-five able-bodied adults performed voluntary isometric ankle plantarflexion contractions to a range of percentages of maximal voluntary torque. Ankle torque, plantarflexor muscle EMG, and voluntary muscle activation measured by twitch interpolation were recorded. EMG recorded at each contraction intensity was normalized to maximal EMG or to Mmax for each plantarflexor muscle, and the relationship between the two normalization approaches quantified. A slope >1 indicated EMG amplitude normalized to maximal EMG (vertical axis) was greater than EMG normalized to Mmax (horizontal axis). Mean estimates of the slopes were large and had moderate precision: soleus 8.7 (95% CI 6.9 to 11.0), medial gastrocnemius 13.4 (10.5 to 17.0), lateral gastrocnemius 11.4 (9.4 to 14.0). This indicates EMG normalized to Mmax is approximately eleven times smaller than EMG normalized to maximal EMG. Normalization to maximal EMG gave closer approximations to the level of voluntary muscle activation assessed by twitch interpolation.

Interventions for improving mobility after hip fracture surgery in adults.

BACKGROUND: Improving mobility outcomes after hip fracture is key to recovery. Possible strategies include gait training, exercise and muscle stimulation. This is an update of a Cochrane Review last published in 2011. OBJECTIVES: To evaluate the effects (benefits and harms) of interventions aimed at improving mobility and physical functioning after hip fracture surgery in adults. SEARCH METHODS: We searched the Cochrane Bone, Joint and Muscle Trauma Group Specialised Register, the Cochrane Central Register of Controlled Trials, MEDLINE, Embase, CINAHL, trial registers and reference lists, to March 2021. SELECTION CRITERIA: All randomised or quasi-randomised trials assessing mobility strategies after hip fracture surgery. Eligible strategies aimed to improve mobility and included care programmes, exercise (gait, balance and functional training, resistance/strength training, endurance, flexibility, three-dimensional (3D) exercise and general physical activity) or muscle stimulation. Intervention was compared with usual care (in-hospital) or with usual care, no intervention, sham exercise or social visit (post-hospital). DATA COLLECTION AND ANALYSIS: Members of the review author team independently selected trials for inclusion, assessed risk of bias and extracted data. We used standard methodological procedures expected by Cochrane. We used the assessment time point closest to four months for in-hospital studies, and the time point closest to the end of the intervention for post-hospital studies. Critical outcomes were mobility, walking speed, functioning, health-related quality of life, mortality, adverse effects and return to living at pre-fracture residence. MAIN RESULTS: We included 40 randomised controlled trials (RCTs) with 4059 participants from 17 countries. On average, participants were 80 years old and 80% were women. The median number of study participants was 81 and all trials had unclear or high risk of bias for one or more domains. Most trials excluded people with cognitive impairment (70%), immobility and/or medical conditions affecting mobility (72%). In-hospital setting, mobility strategy versus control Eighteen trials (1433 participants) compared mobility strategies with control (usual care) in hospitals. Overall, such strategies may lead to a moderate, clinically-meaningful increase in mobility (standardised mean difference (SMD) 0.53, 95% confidence interval (CI) 0.10 to 0.96; 7 studies, 507 participants; low-certainty evidence) and a small, clinically meaningful improvement in walking speed (CI crosses zero so does not rule out a lack of effect (SMD 0.16, 95% CI -0.05 to 0.37; 6 studies, 360 participants; moderate-certainty evidence). Mobility strategies may make little or no difference to short-term (risk ratio (RR) 1.06, 95% CI 0.48 to 2.30; 6 studies, 489 participants; low-certainty evidence) or long-term mortality (RR 1.22, 95% CI 0.48 to 3.12; 2 studies, 133 participants; low-certainty evidence), adverse events measured by hospital re-admission (RR 0.70, 95% CI 0.44 to 1.11; 4 studies, 322 participants; low-certainty evidence), or return to pre-fracture residence (RR 1.07, 95% CI 0.73 to 1.56; 2 studies, 240 participants; low-certainty evidence). We are uncertain whether mobility strategies improve functioning or health-related quality of life as the certainty of evidence was very low. Gait, balance and functional training probably causes a moderate improvement in mobility (SMD 0.57, 95% CI 0.07 to 1.06; 6 studies, 463 participants; moderate-certainty evidence). There was little or no difference in effects on mobility for resistance training. No studies of other types of exercise or electrical stimulation reported mobility outcomes. Post-hospital setting, mobility strategy versus control Twenty-two trials (2626 participants) compared mobility strategies with control (usual care, no intervention, sham exercise or social visit) in the post-hospital setting. Mobility strategies lead to a small, clinically meaningful increase in mobility (SMD 0.32, 95% CI 0.11 to 0.54; 7 studies, 761 participants; high-certainty evidence) and a small, clinically meaningful improvement in walking speed compared to control (SMD 0.16, 95% CI 0.04 to 0.29; 14 studies, 1067 participants; high-certainty evidence). Mobility strategies lead to a small, non-clinically meaningful increase in functioning (SMD 0.23, 95% CI 0.10 to 0.36; 9 studies, 936 participants; high-certainty evidence), and probably lead to a slight increase in quality of life that may not be clinically meaningful (SMD 0.14, 95% CI -0.00 to 0.29; 10 studies, 785 participants; moderate-certainty evidence). Mobility strategies probably make little or no difference to short-term mortality (RR 1.01, 95% CI 0.49 to 2.06; 8 studies, 737 participants; moderate-certainty evidence). Mobility strategies may make little or no difference to long-term mortality (RR 0.73, 95% CI 0.39 to 1.37; 4 studies, 588 participants; low-certainty evidence) or adverse events measured by hospital re-admission (95% CI includes a large reduction and large increase, RR 0.86, 95% CI 0.52 to 1.42; 2 studies, 206 participants; low-certainty evidence). Training involving gait, balance and functional exercise leads to a small, clinically meaningful increase in mobility (SMD 0.20, 95% CI 0.05 to 0.36; 5 studies, 621 participants; high-certainty evidence), while training classified as being primarily resistance or strength exercise may lead to a clinically meaningful increase in mobility measured using distance walked in six minutes (mean difference (MD) 55.65, 95% CI 28.58 to 82.72; 3 studies, 198 participants; low-certainty evidence). Training involving multiple intervention components probably leads to a substantial, clinically meaningful increase in mobility (SMD 0.94, 95% CI 0.53 to 1.34; 2 studies, 104 participants; moderate-certainty evidence). We are uncertain of the effect of aerobic training on mobility (very low-certainty evidence). No studies of other types of exercise or electrical stimulation reported mobility outcomes. AUTHORS' CONCLUSIONS: Interventions targeting improvement in mobility after hip fracture may cause clinically meaningful improvement in mobility and walking speed in hospital and post-hospital settings, compared with conventional care. Interventions that include training of gait, balance and functional tasks are particularly effective. There was little or no between-group difference in the number of adverse events reported. Future trials should include long-term follow-up and economic outcomes, determine the relative impact of different types of exercise and establish effectiveness in emerging economies.

Eccentric exercise improves joint flexibility in adults: A systematic review update and meta-analysis.

BACKGROUND: Eccentric exercise is thought to improve joint flexibility, but the size of the effect is not known. We aimed to quantify the overall effect of eccentric exercise on joint flexibility in adults. DESIGN: Systematic review, meta-analysis. DATA SOURCES: AMED, CINAHL, MEDLINE, EMBASE, SportDiscus. PARTICIPANTS: Adults. INTERVENTION: Eccentric exercise compared to no intervention or to a different intervention. OUTCOME MEASURES: Joint range of motion or muscle fascicle length. DATA EXTRACTION AND SYNTHESIS: Descriptive data of included trials and estimates of effect sizes were extracted. Standardised mean differences (SMD) of range of motion or fascicle length outcomes were meta-analysed using random effects models. Overall quality of evidence was assessed using the GRADE scale. RESULTS: 32 trials (1122 participants, 108 lost to follow-up) were included in the systematic review. The mean (SD) PEDro score was 5.2 (1.3). Four trials reported insufficient data for meta-analysis. Data from 27 trials (911 participants, 82 lost to follow-up) were meta-analysed. Eccentric exercise improved joint flexibility in adults (pooled random effects Hedges' g SMD = 0.54, 95% CI 0.34 to 0.74). The true effect size is different across studies and 50% of the variance in observed effects is estimated to reflect variance in true effects rather than sampling error (I2 = 50%, Q = 67.6, d.f. = 34, p = 0.001). Overall quality of evidence ranged from 'low' to 'high'. CONCLUSION: Eccentric exercise improves joint flexibility in adults. The overall standardised mean effect of eccentric exercise was moderately large, and the narrow width of the 95% confidence interval indicates the effect was estimated with good precision. REGISTRATION: Open Science Foundation (https://osf.io/mkdqr); PROSPERO registration CRD42020151303.

Acute experimentally-induced pain replicates the distribution but not the quality or behaviour of clinical appendicular musculoskeletal pain. A systematic review.

OBJECTIVES: Experimental pain is a commonly used method to draw conclusions about the motor response to clinical musculoskeletal pain. A systematic review was performed to determine if current models of acute experimental pain validly replicate the clinical experience of appendicular musculoskeletal pain with respect to the distribution and quality of pain and the pain response to provocation testing. METHODS: A structured search of Medline, Scopus and Embase databases was conducted from database inception to August 2020 using the following key terms: "experimental muscle pain" OR "experimental pain" OR "pain induced" OR "induced pain" OR "muscle hyperalgesia" OR ("Pain model" AND "muscle"). Studies in English were included if investigators induced experimental musculoskeletal pain into a limb (including the sacroiliac joint) in humans, and if they measured and reported the distribution of pain, quality of pain or response to a provocation manoeuvre performed passively or actively. Studies were excluded if they involved prolonged or delayed experimental pain, if temporomandibular, orofacial, lumbar, thoracic or cervical spine pain were investigated, if a full text of the study was not available or if they were systematic reviews. Two investigators independently screened each title and abstract and each full text paper to determine inclusion in the review. Disagreements were resolved by consensus with a third investigator. RESULTS: Data from 57 experimental pain studies were included in this review. Forty-six of these studies reported pain distribution, 41 reported pain quality and six detailed the pain response to provocation testing. Hypertonic saline injection was the most common mechanism used to induce pain with 43 studies employing this method. The next most common methods were capsaicin injection (5 studies) and electrical stimulation, injection of acidic solution and ischaemia with three studies each. The distribution of experimental pain was similar to the area of pain reported in clinical appendicular musculoskeletal conditions. The quality of appendicular musculoskeletal pain was not replicated with the affective component of the McGill Pain Questionnaire consistently lower than that typically reported by musculoskeletal pain patients. The response to provocation testing was rarely investigated following experimental pain induction. Based on the limited available data, the increase in pain experienced in clinical populations during provocative maneuvers was not consistently replicated. CONCLUSIONS: Current acute experimental pain models replicate the distribution but not the quality of chronic clinical appendicular musculoskeletal pain. Limited evidence also indicates that experimentally induced acute pain does not consistently increase with tests known to provoke pain in patients with appendicular musculoskeletal pain. The results of this review question the validity of conclusions drawn from acute experimental pain studies regarding changes in muscle behaviour in response to pain in the clinical setting.

Strengthening the incentives for responsible research practices in Australian health and medical research funding.

BACKGROUND: Australian health and medical research funders support substantial research efforts, and incentives within grant funding schemes influence researcher behaviour. We aimed to determine to what extent Australian health and medical funders incentivise responsible research practices. METHODS: We conducted an audit of instructions from research grant and fellowship schemes. Eight national research grants and fellowships were purposively sampled to select schemes that awarded the largest amount of funds. The funding scheme instructions were assessed against 9 criteria to determine to what extent they incentivised these responsible research and reporting practices: (1) publicly register study protocols before starting data collection, (2) register analysis protocols before starting data analysis, (3) make study data openly available, (4) make analysis code openly available, (5) make research materials openly available, (6) discourage use of publication metrics, (7) conduct quality research (e.g. adhere to reporting guidelines), (8) collaborate with a statistician, and (9) adhere to other responsible research practices. Each criterion was answered using one of the following responses: "Instructed", "Encouraged", or "No mention". RESULTS: Across the 8 schemes from 5 funders, applicants were instructed or encouraged to address a median of 4 (range 0 to 5) of the 9 criteria. Three criteria received no mention in any scheme (register analysis protocols, make analysis code open, collaborate with a statistician). Importantly, most incentives did not seem strong as applicants were only instructed to register study protocols, discourage use of publication metrics and conduct quality research. Other criteria were encouraged but were not required. CONCLUSIONS: Funders could strengthen the incentives for responsible research practices by requiring grant and fellowship applicants to implement these practices in their proposals. Administering institutions could be required to implement these practices to be eligible for funding. Strongly rewarding researchers for implementing robust research practices could lead to sustained improvements in the quality of health and medical research.

Brief report: Passive mechanical properties of gastrocnemius in multiple sclerosis and ankle contracture.

BACKGROUND: Ankle contracture is common in people with multiple sclerosis (MS) but the mechanisms of contracture are not clear. This study aimed to identify the mechanisms of contracture in MS by comparing passive muscle length and stiffness at known tension, separated into contributions by muscle fascicles and tendons, between people with MS who had contracture and healthy people. METHODS: Passive length-tension curves of the gastrocnemius muscle-tendon unit were derived from passive ankle torque and angle using a published biomechanical method. Ultrasound images of medial gastrocnemius muscle fascicles were used to partition length-tension curves into fascicle and tendon components. Lengths and stiffness of the muscle-tendon unit, muscle fascicles and tendons were compared between groups with linear regression. FINDINGS: Data were obtained from 15 participants with MS who had contracture [age 53 (12) years, mean (SD)] and 25 healthy participants [48 (20) years]. Participants with MS had clinically significant ankle contracture, and had shorter fascicles at slack length (between-groups mean difference -0.8 cm, 95% CI -1.2 to -0.4 cm, p < 0.001) and at 100 N (-0.7 cm, 95% CI -1.3 to -0.1 cm, p = 0.02) compared to healthy participants. There were no differences between groups in all other outcomes. INTERPRETATION: Tension-referenced comparisons of passive muscle length and stiffness show that people with MS who had contracture had shorter fascicles at low and high tension compared to healthy people, but there were no changes to the muscle-tendon unit or tendon. Further studies are needed to identify the causes and mechanisms of contracture in neurological conditions.

Estimation of maximal muscle electromyographic activity from the relationship between muscle activity and voluntary activation.

Maximal muscle activity recorded with surface electromyography (EMG) is an important neurophysiological measure. It is frequently used to normalize EMG activity recorded during passive or active movement. However, the true maximal muscle activity cannot be determined in people with impaired capacity to voluntarily activate their muscles. Here, we determined whether maximal muscle activity can be estimated from muscle activity produced during submaximal voluntary activation. Twenty-five able-bodied adults (18 males, mean age 29 yr, range 19-64 yr) participated in the study. Participants were seated with the knee flexed 90° and the ankle in 5° of dorsiflexion from neutral. Participants performed isometric voluntary ankle plantarflexion contractions at target torques, in random order: 1, 5, 10, 15, 25, 50, 75, 90, 95, and 100% of maximal voluntary torque. Ankle torque, muscle activity in soleus, medial and lateral gastrocnemius muscles, and voluntary muscle activation determined using twitch interpolation were recorded. There was a strong loge-linear relationship between measures of muscle activation and muscle activity in all three muscles tested. Linear mixed models were fitted to muscle activation and loge-transformed EMG data. Each 1% increase in muscle activation increased muscle activity by a mean of 0.027 ln(mV) [95% confidence interval (CI) 0.025 to 0.029 ln(mV)] in soleus, 0.025 ln(mV) [0.022 to 0.028 ln(mV)] in medial gastrocnemius, and 0.028 ln(mV) [0.026 to 0.030 ln(mV)] in lateral gastrocnemius. The relationship between voluntary muscle activation and muscle activity can be described with simple mathematical functions. In future, it should be possible to normalize recorded muscle activity using these types of functions.NEW & NOTEWORTHY Muscle activity is often normalized to maximal muscle activity; however, it is difficult to obtain accurate measures of maximal muscle activity in people with impaired voluntary neural drive. We determined the relationship between voluntary muscle activation and plantarflexor muscle activity across a broad range of muscle activation values in able-bodied people. The relationship between voluntary muscle activation and muscle activity can be described with simple mathematical functions capable of estimating maximal muscle activity.

Association of food industry ties with findings of studies examining the effect of dairy food intake on cardiovascular disease and mortality: systematic review and meta-analysis.

OBJECTIVE: To determine if the association of dairy foods with cardiovascular disease (CVD) outcomes differs between studies with food industry ties versus those without industry ties. To determine whether studies with or without industry ties differ in their risk of bias. ELIGIBILITY CRITERIA: We included cohort and case-control studies that estimated the association of dairy foods with CVD outcomes in healthy adults. INFORMATION SOURCES: We searched eight databases on 1 February 2019 from 2000 to 2019 and hand searched reference lists. RISK OF BIAS: We used the Risk of Bias in Non-Randomised Studies-of Exposure tool. INCLUDED STUDIES: 43 studies (3 case-controls, 40 cohorts). SYNTHESIS OF RESULTS: There was no clear evidence of an association between studies with industry ties (1/14) versus no industry ties (8/29) and the reporting of favourable results, risk ratio (RR)=0.26 (95% CI 0.04 to 1.87; n=43 studies) and studies with industry ties (4/14) versus no industry ties (11/29) and favourable conclusions, RR=0.75 (95% CI 0.29 to 1.95; n=43). Studies with industry sponsorship, (HR=0.78; n=3 studies) showed a decreased magnitude of risk of CVD outcomes compared with studies with no industry sponsorship (HR=0.97; n=18) (ratio of HRs 0.80 (95% CI 0.66 to 0.97); p=0.03). STRENGTHS AND LIMITATIONS OF EVIDENCE: Every study had an overall high risk of bias rating; this was primarily due to confounding. INTERPRETATION: There was no clear evidence of an association between studies with food industry ties and the reporting of favourable results and conclusions compared with studies without industry ties. The statistically significant difference in the magnitude of effects identified in industry-sponsored studies compared with non-industry-sponsored studies, however, is important in quantifying industry influence on studies included in dietary guidelines. PROSPERO REGISTRATION NUMBER: CRD42019129659.

History-dependence of muscle slack length in humans: effects of contraction intensity, stretch amplitude, and time.

The slack length of a relaxed skeletal muscle can be reduced by isometric contraction at short lengths ("contract-short conditioning"). This study explored how the effect of contract-short conditioning on muscle slack length is modified by 1) the intensity of the contraction, 2) the delay between the contraction and measurement of slack length, and 3) the amplitude of a stretch delivered to the relaxed muscle after the contraction. Muscle fascicles in the human vastus lateralis muscle were observed with ultrasound imaging while the relaxed muscle was lengthened by flexing the knee. The knee angle at which muscle fascicle slack was taken up was used as a proxy for muscle slack length. Conditioning the muscle with voluntary isometric (fixed-end) contractions at short muscle lengths reduced vastus lateralis muscle slack length, measured 60 s later, by a mean of 10°. This effect was independent of contraction intensity from 5% to 100% maximal voluntary contraction. The effect was largest when first observed 5 s after the contraction, decayed about one-third by 60 s, and then remained nearly constant until the last observation 5 min after the contraction. A slow stretch given to the relaxed muscle after contract-short conditioning increased slack length (i.e., reduced the effect of contract-short conditioning). Slack length increased nonlinearly with stretch amplitude. Very large stretches (>30°, possibly as large as 90°) were required to abolish the effect of contract-short conditioning. The phenomena described here share some characteristics with, and may involve similar mechanisms to, passive force enhancement and muscle thixotropy.NEW & NOTEWORTHY The slack length of a relaxed human skeletal muscle is not fixed; it can be modified by contraction and stretch. Contraction of the human vastus lateralis muscle at short lengths reduces the muscle's slack length. Even very weak contractions are sufficient to induce this effect. The effect persists for at least 5 min but can be reduced or abolished with a large-amplitude passive stretch.

Experimental shoulder pain models do not validly replicate the clinical experience of shoulder pain.

Background and aims People with shoulder pain often present with abnormal shoulder muscle function. It is not known whether shoulder pain causes or is the result of muscle dysfunction. If pain leads to muscle dysfunction, therapeutic interventions that produce shoulder pain may be contraindicated. Experimentally induced nociception can be used to investigate a causal relationship between shoulder pain and muscle dysfunction. However, the validity of current experimental shoulder pain protocols has not been established. The aim of this study was to determine whether current experimental shoulder pain protocols validly replicate the clinical experience of shoulder pain with respect to pain distribution, quality and behaviour. Methods Nine pain free participants received two injections of hypertonic saline, one into the subacromial space and one into supraspinatus, in random order, at least 1 week apart. Investigators blind to the injection site assessed pain distribution, pain response to clinical tests which provoke shoulder pain and pain quality assessed using the McGill Pain Questionnaire. Results Following hypertonic saline injection into both the subacromial space and supraspinatus: pain was most commonly reported in the deltoid region and did not extend beyond the elbow; the most common response to clinical tests which provoke shoulder pain was a decrease in pain; and the highest rating of pain quality was in the sensory domain with very few responses in the affective domain. Conclusions Experimental shoulder pain induced by injection of hypertonic saline into either the subacromial space or supraspinatus produced a pain distribution similar to that observed in clinical shoulder pain, but neither experimental pain protocol could reproduce the increases in pain intensity following shoulder provocation tests or the emotional distress commonly observed in people with clinical shoulder pain. Implications Pain induced by local shoulder nociception produced by hypertonic saline injection into shoulder structures has significant limitations as a model of clinical shoulder pain. While it is perhaps unsurprising that short duration, chemically-induced experimental pain does not replicate the quality of the clinical experience of shoulder pain, the validity of experimental shoulder pain models which produce the opposite response to provocation testing to clinical shoulder pain must be questioned.

Thumb and finger movement is reduced after stroke: An observational study.

Hand motor impairment is common after stroke but there are few comprehensive data on amount of hand movement. This study aimed to compare the amount of thumb and finger movement over an extended period of time in people with stroke and able-bodied people. Fifteen stroke subjects and 15 able-bodied control subjects participated. Stroke subjects had impaired hand function. Movement of the thumb and index finger was recorded using stretch sensors worn on the affected hand (stroke subjects) or the left or right hand (control subjects) for ∼4 hours during the day. A digit movement was defined as a monotonic increase or decrease in consecutive sensor values. Instantaneous digit position was expressed as a percentage of maximal digit flexion. Mixed linear models were used to compare the following outcomes between groups: (1) average amplitude of digit movement, (2) digit cadence and average digit velocity, (3) percentage of digit idle time and longest idle time. Amplitude of digit movement was not different between groups. Cadence at the thumb (between-group mean difference, 95% CI, p value: -0.6 movements/sec, -1.0 to -0.2 movements/sec, p = 0.003) and finger (-0.5 movements/sec, -0.7 to -0.3 movements/sec, p<0.001) was lower in stroke than control subjects. Digit velocity was not different between groups. Thumb idle time was not different between groups, but finger idle time was greater in stroke than control subjects (percentage of idle time: 6%, 1 to 11%, p = 0.02; longest idle time: 375 sec, 29 to 721 sec, p = 0.04). Rehabilitation after stroke should encourage the performance of functional tasks that involve movements at faster cadences, and encourage more frequent movement of the digits with shorter periods of inactivity.

Small amounts of involuntary muscle activity reduce passive joint range of motion.

When assessing passive joint range of motion in neurological conditions, concomitant involuntary muscle activity is generally regarded small enough to ignore. This assumption is untested. If false, many clinical and laboratory studies that rely on these assessments may be in error. We determined to what extent small amounts of involuntary muscle activity limit passive range of motion in 30 able-bodied adults. Subjects were seated with the knee flexed 90° and the ankle in neutral, and predicted maximal plantarflexion torque was determined using twitch interpolation. Next, with the knee flexed 90° or fully extended, the soleus muscle was continuously electrically stimulated to generate 1, 2.5, 5, 7.5, and 10% of predicted maximal torque, in random order, while the ankle was passively dorsiflexed to a torque of 9 N·m by a blinded investigator. A trial without stimulation was also performed. Ankle dorsiflexion torque-angle curves were obtained at each percent of predicted maximal torque. On average (mean, 95% confidence interval), each 1% increase in plantarflexion torque decreases ankle range of motion by 2.4° (2.0 to 2.7°; knee flexed 90°) and 2.3° (2.0 to 2.5°; knee fully extended). Thus 5% of involuntary plantarflexion torque, the amount usually considered small enough to ignore, decreases dorsiflexion range of motion by ~12°. Our results indicate that even small amounts of involuntary muscle activity will bias measures of passive range and hinder the differential diagnosis and treatment of neural and nonneural mechanisms of contracture. NEW & NOTEWORTHY The soleus muscle in able-bodied adults was tetanically stimulated while the ankle was passively dorsiflexed. Each 1% increase in involuntary plantarflexion torque at the ankle decreases the range of passive movement into dorsiflexion by >2°. Thus the range of ankle dorsiflexion decreases by ~12° when involuntary plantarflexion torque is 5% of maximum, a torque that is usually ignored. Thus very small amounts of involuntary muscle activity substantially limit passive joint range of motion.

Involuntary hamstring muscle activity reduces passive hip range of motion during the straight leg raise test: a stimulation study in healthy people.

BACKGROUND: Involuntary hamstring muscle activity is present in some people during the straight leg raise test, but it is not known to what extent involuntary muscle activity limits passive joint range of motion. This study aimed to determine whether small amounts of involuntary hamstring activity limit passive hip range of motion during the straight leg raise test in healthy people. METHODS: Thirty healthy subjects were recruited from The University of Sydney. As the hamstring muscles were continuously stimulated to generate 0, 2.5, 5, 7.5 and 10% of knee flexion maximal voluntary contraction force, an investigator blinded to the amount of stimulation performed a straight leg raise test by passively raising the tested leg while keeping the knee extended. The test was stopped when the knee started to flex, at which point hip range of motion was recorded. RESULTS: On average, passive hip range of motion decreased by 0.6° for every 1% increase in knee flexion force caused by muscle activation (95% CI 0.3 to 0.9°, p = 0.0012). Subjects were instructed to fully relax when the straight leg raise test was performed, but a small amount of involuntary muscle activity (median 2.4% of maximal activation) was present during the trial without stimulation. CONCLUSIONS: Small amounts of involuntary hamstring muscles activity reduce passive hip range of motion during the straight leg raise test in healthy people. TRIAL REGISTRATION: The protocol for this study was registered with the Open Science Framework, reference: https://osf.io/fejpf/ . Registered 9 March 2017.