Association between hip muscle strength/function and hip cartilage defects in sub-elite football players with hip/groin pain.

OBJECTIVE: To explore associations between hip muscle strength and cartilage defects (presence and severity) on magnetic resonance imaging (MRI) in young adults with hip/groin pain participating in sub-elite football. DESIGN: Sub-elite football players with hip/groin pain (>6 months) completed assessments of isometric hip strength and functional task performance. Hip cartilage defects were assessed using the Scoring Hip Osteoarthritis with MRI tool. This exploratory, cross-sectional study used logistic and negative binomial models to assess the relationships between hip muscle strength or functional task performance and hip cartilage defects, controlling for body mass index, age, testing site and cam morphology, incorporating sex-specific interaction terms. RESULTS: One hundred and eighty-two (37 women) sub-elite (soccer or Australian football) players with hip/groin pain (age 26 ± 7 years) were included. Greater hip extension strength was associated with higher cartilage total score (adjusted incidence rate ratio [aIRR] 1.01, 95%CI: 1.0 to 1.02, p = 0.013) and superolateral cartilage score (adjusted odds ratio (aOR) 1.03, 95% confidence interval (CI): 1.01 to 1.06, p < 0.01). In female sub-elite football players, greater hip external rotation strength was associated with lateral cartilage defects (aOR 1.61, 95%CI: 1.05 to 2.48, p = 0.03) and higher cartilage total score (aIRR 1.25, 95%CI: 1.01 to 1.66, p = 0.042). A one-repetition increase in one-leg rise performance was related to lower odds of superomedial cartilage defects (aOR 0.96, 95%CI: 0.94 to 0.99, p < 0.01). CONCLUSIONS: Overall, there were few associations between peak isometric hip muscle strength and overall hip cartilage defects. It is possible that other factors may have relevance in sub-elite football players. Additional studies are needed to support or refute our findings that higher one leg rise performance was associated with reduced superomedial cartilage defect severity and greater hip extension strength was related to higher cartilage defect severity scores.

The association between hip/groin pain and hip strength in football players: An exploratory analysis of the FORCe cohort.

OBJECTIVES: Explore associations between peak hip strength in football players with hip/groin pain and healthy controls. DESIGN: Cross-sectional study. METHODS: Male and female sub-elite football players (soccer and Australian football) with hip/groin pain >6-month duration and players without hip/groin pain were recruited across Melbourne and Brisbane, Australia. Demographic information and two questionnaires; the Copenhagen Hip and Groin Outcome Score and the International Hip Outcome Tool 33 were collected. Hand-held dynamometry was used to measure isometric hip strength for flexion, extension, abduction, adduction, internal rotation, and external rotation. Linear mixed effects models were used to compare strength measures between groups. RESULTS: 190 football players with hip/groin pain (mean ±â€¯standard deviation age, 27.8 ±â€¯6.3 years) and 64 controls (age, 27.3 ±â€¯5.6 years) were included in this study. Of these, 291 symptomatic limbs and 128 control limbs were used for analyses. Symptomatic players had lower peak hip adduction (adjusted mean difference = -0.18: 95 % confidence interval -0.27 to -0.08, P : 0.001), external rotation (-0.06: 95 % confidence interval -0.09 to -0.02, P : 0.003), and internal rotation strength (-0.06: 95 % confidence interval -0.10 to -0.03, P : 0.001) compared to controls. A sport-specific interaction was observed for hip abduction strength. When separated by football code, abduction strength was lower in symptomatic Australian football players compared to their same sport peers (-0.20: 95 % confidence interval -0.33 to -0.06, P : 0.004), but not in symptomatic soccer players (-0.05: 95 % confidence interval -0.15 to 0.06, P : 0.382). CONCLUSIONS: Hip adduction, internal rotation, and external rotation strength appears lower in football players with hip/groin pain independent of sex and football code. Hip abduction strength was lower in symptomatic Australian football players but not in soccer players.

Is running good or bad for your knees? A systematic review and meta-analysis of cartilage morphology and composition changes in the tibiofemoral and patellofemoral joints.

BACKGROUND: The general health benefits of running are well-established, yet concern exists regarding the development and progression of osteoarthritis. AIM: To systematically review the immediate (within 20 min) and delayed (20 min-48 h) effect of running on hip and knee cartilage, as assessed using magnetic resonance imaging (MRI). METHOD: Studies using MRI to measure change in hip or knee cartilage within 48 h pre- and post-running were identified. Risk of bias was assessed using a modified Newcastle-Ottawa Scale. Percentage change in cartilage outcomes were estimated using random-effects meta-analysis. Certainty of evidence was evaluated with the Grading of Recommendations Assessment, Development and Evaluation tool. RESULTS: Twenty-four studies were included, evaluating 446 knees only. One third of studies were low risk of bias. Knee cartilage thickness and volume decreased immediately after running, with declines ranging from 3.3% (95% confidence interval [CI]: 2.6%, 4.1%) for weight-bearing femoral cartilage volume to 4.9% (95% CI: 4.43.6%, 6.2%) for patellar cartilage volume. T1ρ and T2 relaxation times were also reduced immediately after running, with the largest decline being 13.1% (95% CI: -14.4%, -11.7%) in femoral trochlear cartilage. Tibiofemoral cartilage T2 relaxation times recovered to baseline levels within 91 min. Existing cartilage defects were unchanged within 48 h post-run. CONCLUSIONS: There is very low certainty evidence that running immediately decreases the thickness, volume, and relaxation times of patellofemoral and tibiofemoral cartilage. Hip cartilage changes are unknown, but knee changes are small and appear transient suggesting that a single bout of running is not detrimental to knee cartilage.

The association between statistical shape modeling-defined hip morphology and features of early hip osteoarthritis in young adult football players: Data from the femoroacetabular impingement and hip osteoarthritis cohort (FORCe) study.

Objective: To explore the relationship between radiographic hip shape and features of early hip osteoarthritis (OA) on magnetic resonance imaging (MRI) in young male and female football players without radiographic hip OA. Design: We used baseline data from a cohort of symptomatic and asymptomatic football players aged 18-50 years. Hip shape was assessed on anteroposterior radiographs with statistical shape modeling (SSM) for men and women separately. Cartilage defects and labral tears were graded using the Scoring Hip Osteoarthritis with MRI (SHOMRI) system. We used logistic regression with generalized estimating equations to estimate associations between each hip shape variant, called shape modes, and cartilage defects or labral tears. Results: We included 229 participants (446 hips, 77.4% male). For each sex, 15 shape modes were analyzed. In men, three shape modes were associated with cartilage defects: adjusted odds ratios (aOR) 0.75 (95%CI 0.58-0.97) per standard deviation (SD) for mode 1; 1.34 (95%CI 1.05-1.69) per SD for mode 12; and 0.61 (95%CI 0.48-0.78) per SD for mode 15; and one also with labral tears: aOR 1.30 (95%CI 1.01-1.69) per SD for mode 12. These modes generally represented variations in the femoral neck and subtypes of cam morphology, with and without pincer morphology. For women, there was no evidence for associations with the outcomes. Conclusions: Several hip shape variants were associated with cartilage defects on MRI in young male football players. Specifically, one subtype of cam morphology was associated with both cartilage defects and labral tears. Hip shape was not associated with early OA features in women.

"Much better than I thought it was going to be": Telehealth delivered group-based education and exercise was perceived as acceptable among people with knee osteoarthritis.

Objective: To understand patient perceived acceptability of participating in a telehealth delivered group-based education and exercise-therapy program for knee osteoarthritis. Design: This qualitative study involved semi-structured, one-on-one interviews with knee osteoarthritis patients who have completed the Good Living with osteoArthritis from Denmark (GLA:D®) program via telehealth or in-person. Interviews were recorded, transcribed verbatim, coded, and analysed using an inductive content analysis approach, focusing on themes related to telehealth. Results: Nineteen participants [12 (63%) female, mean aged 62 years, range 49-72 years] were included. Eleven (58%) received GLA:D® via telehealth and 8 (42%) attended in-person sessions. Two overarching themes (6 sub-themes) related to telehealth perceived acceptability were identified: 1) Perceptions of telehealth acceptability was highly influenced by exposure. Individuals who had received telehealth considered it easy, convenient, and flexible, whereas telehealth was perceived to be inferior and misunderstood by those without exposure. 2) Telehealth participants reported similar program benefits to in-person participants, including reduced fear of pain and joint damage, changed beliefs in value of exercise, and stated improvements in pain and function. Conclusions: Telehealth delivery of group-based education and exercise-therapy for knee osteoarthritis was acceptable for people who had experienced it and provides similar benefits as in-person care for pain and beliefs about the safety and value of exercise. Wider implementation of telehealth group-based education and exercise-therapy may improve access to high value care for people with knee osteoarthritis.

Immediate outcomes following the GLA:D® program in Denmark, Canada and Australia. A longitudinal analysis including 28,370 patients with symptomatic knee or hip osteoarthritis.

OBJECTIVE: To report outcomes across three countries for patients with symptomatic knee or hip OA attending the evidence-based education and exercise therapy program Good Life with osteoArthritis from Denmark (GLA:D®). DESIGN: GLA:D® is a structured treatment program including 2-3 patient education sessions and 12 supervised exercise sessions delivered over 8 weeks by certified health care practitioners. The program was introduced in Denmark in 2013, in Canada 2015 and in Australia 2016. Absolute mean change in pain intensity, number of chair stands in 30 s, 40 m walk test time and Knee injury and Osteoarthritis Outcome Score (KOOS)/Hip dysfunction and Osteoarthritis Outcome Score (HOOS) QOL subscale scores from baseline to immediately after treatment were reported as means and 95 % CIs and proportion of responders for each country. RESULTS: Patients from the three countries improved 26-33% in mean pain intensity, 8-12% in walking speed, 18-30% in chair stand ability and 12-26% in joint-related quality of life from baseline to immediately after treatment, with no clinically relevant differences between patients with hip and knee OA. These improvements correspond with moderate to large within-group effect sizes and 43-47 % of the patients experienced clinically relevant pain reductions. CONCLUSION: About half or more of patients across the three countries were categorized as responders for pain and objective function following the implementation of GLA:D®. These findings indicate positive patient outcomes associated with GLA:D® participation across varying health care systems from implementation of guideline-based patient education and exercise therapy for knee and hip OA.

Prevalence of early hip OA features on MRI in high-impact athletes. The femoroacetabular impingement and hip osteoarthritis cohort (FORCe) study.

OBJECTIVE: To compare early hip osteoarthritis (OA) features on magnetic resonance imaging (MRI) in high-impact athletes with and without hip and/or groin pain, and to evaluate associations between early hip OA features, the International Hip Outcome Tool (iHOT33) and Copenhagen Hip and Groin Outcome Score (HAGOS). DESIGN: This case-control study evaluated data of the femoroacetabular impingement and hip osteoarthritis cohort (FORCe). One hundred and eighty-two symptomatic (hip and/or groin pain >6 months and positive flexion-adduction-internal-rotation (FADIR) test) and 55 pain-free high-impact athletes (soccer or Australian football (AF)) without definite radiographic hip OA underwent hip MRI. The Scoring Hip Osteoarthritis with MRI (SHOMRI) method quantified and graded the severity of OA features. Each participant completed the iHOT33 and HAGOS. RESULTS: Hip and/or groin pain was associated with higher total SHOMRI (0-96) (mean difference 1.4, 95% CI: 0.7-2.2), labral score (adjusted incidence rate ratio (aIRR) 1.33, 95% CI: 1.1-1.6). Differences in prevalence of cartilage defects, labral tears and paralabral cysts between symptomatic and pain-free participants were inconclusive. There was a lower prevalence of effusion-synovitis in symptomatic participants when compared to pain-free participants (adjusted odds ratio (aOR) 0.46 (95% CI: 0.3-0.8). Early hip OA features were not associated with iHOT33 or HAGOS. CONCLUSIONS: A complex and poorly understood relationship exists between hip and/or groin pain and early hip OA features present on MRI in high-impact athletes without radiographic OA. Hip and/or groin pain was associated with higher SHOMRI and labral scores.

Emergence of early alterations in network oscillations and functional connectivity in a tau seeding mouse model of Alzheimer's disease pathology.

Synaptic dysfunction and disconnectivity are core deficits in Alzheimer's disease (AD), preceding clear changes in histopathology and cognitive functioning. Here, the early and late effects of tau pathology induction on functional network connectivity were investigated in P301L mice. Multichannel EEG oscillations were used to compute (1) coherent activity between the prefrontal cortex (PFC) and hippocampus (HPC) CA1-CA3 networks; (2) phase-amplitude cross frequency coupling (PAC) between theta and gamma oscillations, which is instrumental in adequate cognitive functioning; (3) information processing as assessed by auditory evoked potentials and oscillations in the passive oddball mismatch negativity-like (MMN) paradigm. At the end, the density of tau aggregation and GABA parvalbumin (PV+) interneurons were quantified by immunohistochemistry. Early weakening of EEG theta oscillations and coherent activity were revealed between the PFC and HPC CA1 and drastic impairments in theta-gamma oscillations PAC from week 2 onwards, while PV+ interneurons count was not altered. Moreover, the tau pathology disrupted the MMN complex amplitude and evoked gamma oscillations to standard and deviant stimuli suggesting altered memory formation and recall. The induction of intracellular tau aggregation by tau seed injection results in early altered connectivity and strong theta-gamma oscillations uncoupling, which may be exploited as an early electrophysiological signature of dysfunctional neuronal networks.

Early changes in Achilles tendon behaviour in vivo following downhill backwards walking.

Downhill backwards walking causes repeated, cyclical loading of the muscle-tendon unit. The effect this type of repeated loading has on the mechanical behaviour of the Achilles tendon is presently unknown. This study aimed to investigate the biomechanical response of the Achilles tendon aponeurosis complex following a downhill backwards walking protocol. Twenty active males (age: 22.3 ± 3.0 years; mass: 74.7 ± 5.6 kg; height: 1.8 ± 0.7 m) performed 60 min of downhill (8.5°), backwards walking on a treadmill at -0.67 m · s(-1). Data were collected before, immediately post, and 24-, 48- and 168-h post-downhill backwards walking. Achilles tendon aponeurosis elongation, strain and stiffness were measured using ultrasonography. Muscle force decreased immediately post-downhill backward walking (P = 0.019). There were increases in Achilles tendon aponeurosis stiffness at 24-h post-downhill backward walking (307 ± 179.6 N · mm(-1), P = 0.004), and decreases in Achilles tendon aponeurosis strain during maximum voluntary contraction at 24 (3.8 ± 1.7%, P = 0.008) and 48 h (3.9 ± 1.8%, P = 0.002) post. Repeated cyclical loading of downhill backwards walking affects the behaviour of the muscle-tendon unit, most likely by altering muscle compliance, and these changes result in tendon stiffness increases.

Translational neurophysiological markers for activity of the metabotropic glutamate receptor (mGluR2) modulator JNJ-40411813: Sleep EEG correlates in rodents and healthy men.

Alterations in rapid eye movement sleep (REM) have been suggested as valid translational efficacy markers: activation of the metabotropic glutamate receptor 2 (mGluR2) was shown to increase REM latency and to decrease REM duration. The present paper addresses the effects on vigilance states of the mGluR2 positive allosteric modulator (PAM) JNJ-40411813 at different circadian times in rats and after afternoon dosing in humans. Due to its dual mGluR2 PAM/serotonin 2A (5-HT2A) receptor antagonism in rodents, mGlu2R specificity of effects was studied in wild-type (WT) and mGluR2 (-/-) mice. 5-HT2A receptor occupancy was determined in humans using positron emission tomography (PET). Tolerance development was examined in rats after chronic dosing. EEG oscillations and network connectivity were assessed using multi-channel EEG. In rats, JNJ-40411813 increased deep sleep time and latency of REM onset but reduced REM time when administered 2 h after 'lights on' (CT2): this was sustained after chronic dosing. At CT5 similar effects were elicited, at CT10 only deep sleep was enhanced. Withdrawal resulted in baseline values, while re-administration reinstated drug effects. Parieto-occipital cortical slow theta and gamma oscillations were correlated with low locomotion. The specificity of functional response was confirmed in WT but not mGluR2 (-/-) mice. A double-blind, placebo-controlled polysomnographic study in healthy, elderly subjects showed that 500 mg of JNJ-40411813 consistently increased deep sleep time, but had no effect on REM parameters. This deep sleep effect was not explained by 5-HT2A receptor binding, as in the PET study even 700 mg only marginally displaced the tracer. JNJ-40411813 elicited comparable functional responses in rodents and men if circadian time of dosing was taken into account. These findings underscore the translational potential of sleep mechanisms in evaluating mGluR2 therapeutics when administered at the appropriate circadian time.

OARSI Clinical Trials Recommendations: Design and conduct of clinical trials for primary prevention of osteoarthritis by joint injury prevention in sport and recreation.

The risk of post-traumatic osteoarthritis (PTOA) substantially increases following joint injury. Research efforts should focus on investigating the efficacy of preventative strategies in high quality randomized controlled trials (RCT). The objective of these OARSI RCT recommendations is to inform the design, conduct and analytical approaches to RCTs evaluating the preventative effect of joint injury prevention strategies. Recommendations regarding the design, conduct, and reporting of RCTs evaluating injury prevention interventions were established based on the consensus of nine researchers internationally with expertise in epidemiology, injury prevention and/or osteoarthritis (OA). Input and resultant consensus was established through teleconference, face to face and email correspondence over a 1 year period. Recommendations for injury prevention RCTs include context specific considerations regarding the research question, research design, study participants, randomization, baseline characteristics, intervention, outcome measurement, analysis, implementation, cost evaluation, reporting and future considerations including the impact on development of PTOA. Methodological recommendations for injury prevention RCTs are critical to informing evidence-based practice and policy decisions in health care, public health and the community. Recommendations regarding the interpretation and conduct of injury prevention RCTs will inform the highest level of evidence in the field. These recommendations will facilitate between study comparisons to inform best practice in injury prevention that will have the greatest public health impact.

The incidence and burden of hospital-treated sports-related injury in people aged 15+ years in Victoria, Australia, 2004-2010: a future epidemic of osteoarthritis?

OBJECTIVES: Previous sports injury is a known risk factor for subsequent osteoarthritis (OA), but population-based rates of sports injury are unknown. The aims of this study were to: (1) describe the trends in the population incidence and burden of all hospital-treated sports injury in Victoria, Australia in adults aged 15+ years; (2) determine the incidence of lower limb and knee injuries; and (3) quantify their population health burden as average direct hospital costs per injury and lengths of stay. METHODS: Health sector data relating to adults aged 15+ years, for 2004-2010 inclusive, was extracted from the Victorian Admitted Episodes Dataset (VAED) and Victorian Emergency Minimum Dataset (VEMD). Data relating to sports injuries were identified using activity codes in each dataset Trends in injury frequency and rates were determined, and economic burden was calculated. RESULTS: The overall annual rate of hospital treated sports injuries increased by 24% (P = 0.001), and lower limb injuries by 26% (P = 0.001) over the 7 years. The associated accumulated economic burden was $265 million for all sports injuries and $110 million for lower limb injuries over the 7-years. CONCLUSIONS: The findings of this study show a significant increase in sports injuries in the state of Victoria, Australia over a 7-year period. As previous sports injury is a risk factor for the development of OA, the future incidence of OA will escalate, placing an even greater burden on health care systems. Population-wide preventative strategies that reduce the risk of sports injury are urgently required in order to reduce the future burden of OA.

Patient-Reported Outcome (PRO) questionnaires for young to middle-aged adults with hip and groin disability: a systematic review of the clinimetric evidence.

BACKGROUND/AIM: To recommend Patient-Reported Outcome (PRO) questionnaires to measure hip and groin disability in young-aged to middle-aged adults. METHODS: A systematic review was performed in June 2014. The methodological quality of the studies included was determined using the COnsensus-based Standards for the selection of health Measurement INstruments list (COSMIN) together with standardised evaluations of measurement properties of each PRO. RESULTS: Twenty studies were included. Nine different questionnaires for patients with hip disability, and one for hip and groin disability, were identified. Hip And Groin Outcome Score (HAGOS), Hip Outcome Score (HOS), International Hip Outcome Tool-12 (IHOT-12) and IHOT-33 were the most thoroughly investigated PROs and studies including these PROs reported key aspects of the COSMIN checklist. HAGOS and IHOT-12 were based on studies with the least ratings of poor study methodology (23% and 31%, respectively), whereas IHOT-33 and HOS had a somewhat larger distribution (46%). These PROs all contain adequate measurement qualities for content validity (except HOS), test-retest reliability, construct validity, responsiveness and interpretability. No information or poor quality rating on methodological aspects made it impossible to fully evaluate the remaining PROs at present. CONCLUSIONS: HAGOS, HOS, IHOT-12 and IHOT-33 can be recommended for assessment of young-aged to middle-aged adults with pain related to the hip joint, undergoing non-surgical treatment or hip arthroscopy. At present, HAGOS is the only PRO also aimed for young-aged to middle-aged adults presenting with groin pain and is recommended for use in this population. TRIAL REGISTRATION NUMBER: CRD42014009995.

The association between inhibition and pain tolerance in the elderly: evidence from event-related potentials.

BACKGROUND: Age-related alterations in both pain perception and inhibitory functions have been observed, but the relationship between the two in older adults remains unclear. Previous studies were mainly based on behavioural measures which do not allow assessment of underlying neural mechanisms. METHODS: The present study evaluated the association between inhibition and pain perception in 26 healthy elderly volunteers. Cognitive inhibition was assessed by Stroop interference tests and response inhibition by a Go/No-go task. Event-related potentials during the Go/No-go task were recorded to provide brain activity data. Pain perception was assessed with the cold pressor test, in which subjects were asked to resist pain as long as possible. The exposure time (ET), intensity of tolerated pain and unpleasantness were interpreted as psychophysiological outcomes of pain. RESULTS: We observed that better performance on cognitive inhibition, assessed by Stroop interference tasks, was correlated with higher intensity of tolerated pain. Greater brain activity during response inhibition, evaluated as larger amplitude (P3), and shorter latency (N2) to a No-go stimuli were correlated with longer ET-pain tolerance. CONCLUSIONS: In the healthy elderly, the neuronal circuits of cognitive inhibition and conscious pain control may overlap, and brain regions engaged in response inhibition may be more involved in behavioural response of pain.

Is hip range of motion and strength impaired in people with hip chondrolabral pathology?

OBJECTIVE: The aims of this study were to: i) to compare physical impairments in people with chondrolabral pathology identified at hip arthroscopy 12-24 months previously to age-matched healthy people; and ii) to understand whether sex has any influence on impairments. METHODS: 84 patients (42 female; age=36±10) 12-24 months post hip arthroscopy and 60 controls (41 female; age=36±10) were included. Measurements of active hip ROM and strength were assessed. Two-way analyses of co-variance examined the effect of sex and chondrolabral pathology on hip ROM and strength. RESULTS: Patients exhibited less hip internal rotation (IR) ROM (p=0.001) and more extension (p=0.014) ROM; and less hip adduction (p<0.001), extension (p=0.001), flexion (p<0.001), ER (p=0.044) and IR (p<0.001) strength when compared to controls. For abduction strength, a significant interaction was found between the presence of chondrolabral pathology and sex (p=0.035). CONCLUSIONS: People with hip chondrolabral pathology have differences in hip ROM and strength when compared to controls. Rehabilitation programs should focus on addressing these specific physical impairments in order to enhance outcomes. This information may be of great value to both researchers and clinicians alike in determining interventions to improve outcomes in people with early hip OA.

Childhood intelligence is heritable, highly polygenic and associated with FNBP1L.

Intelligence in childhood, as measured by psychometric cognitive tests, is a strong predictor of many important life outcomes, including educational attainment, income, health and lifespan. Results from twin, family and adoption studies are consistent with general intelligence being highly heritable and genetically stable throughout the life course. No robustly associated genetic loci or variants for childhood intelligence have been reported. Here, we report the first genome-wide association study (GWAS) on childhood intelligence (age range 6-18 years) from 17,989 individuals in six discovery and three replication samples. Although no individual single-nucleotide polymorphisms (SNPs) were detected with genome-wide significance, we show that the aggregate effects of common SNPs explain 22-46% of phenotypic variation in childhood intelligence in the three largest cohorts (P=3.9 × 10(-15), 0.014 and 0.028). FNBP1L, previously reported to be the most significantly associated gene for adult intelligence, was also significantly associated with childhood intelligence (P=0.003). Polygenic prediction analyses resulted in a significant correlation between predictor and outcome in all replication cohorts. The proportion of childhood intelligence explained by the predictor reached 1.2% (P=6 × 10(-5)), 3.5% (P=10(-3)) and 0.5% (P=6 × 10(-5)) in three independent validation cohorts. Given the sample sizes, these genetic prediction results are consistent with expectations if the genetic architecture of childhood intelligence is like that of body mass index or height. Our study provides molecular support for the heritability and polygenic nature of childhood intelligence. Larger sample sizes will be required to detect individual variants with genome-wide significance.

Differences in age-related effects on myelinated and unmyelinated peripheral fibres: a sensitivity and evoked potentials study.

BACKGROUND: Experimental data regarding age effects on sensitivity and pain thresholds are not always consistent, with the type of stimulus being a major source of variability. This could suggest that some types of peripheral sensory fibres undergo more important modifications with age than others. We investigated whether ageing affects differently myelinated and unmyelinated fibres. METHODS: Somatosensitivity and pain perception and recorded somatosensory evoked potentials (SEPs) were assessed in younger and older adults during the selective activation of either myelinated Aδ- or unmyelinated C-fibres. RESULTS: Somatosensitivity for information transmitted and SEPs elicited by stimulation of C-fibres did not differ between both groups. In contrast, pain perception was lower in older than in younger adults, and older adults showed longer SEP latencies and reduced peak-to-peak amplitude, during selective stimulation of Aδ-fibres. CONCLUSIONS: These findings suggest that myelinated Aδ-fibres are compromised by the normal ageing process, whereas unmyelinated C-fibres seem to remain unaltered or, at least, less affected.

Age-related decrease in sensitivity to electrical stimulation is unrelated to skin conductance: an evoked potentials study.

OBJECTIVE: With aging, skin is likely to become less hydrated, thereby increasing its resistance to electrical current. This, rather than sensorial/perceptual differences per se, may be the primary cause of differences between younger and older adults in somatosensorial perception in response to electrical stimuli. METHODS: To assess whether aging alters the perception of electrical stimulation, we compared the perceived intensity of electrical stimuli in younger and older subjects, considering both setpoint intensities and the actual intensities of the current passing through subjects' skin. This resulted in reliable information about electrical somatosensory perception in both groups at equivalent received amounts of current. Somatosensory evoked potentials (SEPs) enabled the objective evaluation of somatosensitivity in both groups. RESULTS: At equivalent received intensities, the mean ratings were significantly lower in older than in younger subjects. SEPs confirmed these results, with older adults having longer latencies and reduced amplitudes. CONCLUSIONS: Our results suggest that age-related decreases in somatosensitivity to electrical stimuli are not due to cutaneous physiological changes. SIGNIFICANCE: Age-related increases in electrical somatosensorial and pain thresholds seem to be more attributable to dysfunctions of the peripheral and/or central nervous system, than to non-optimal activation of somatosensorial receptors/nerve fibers due to cutaneous physiological changes.

Can local muscles augment stability in the hip? A narrative literature review.

Hip pain and dysfunction are increasingly recognised as important causes of morbidity in younger and older adults. Pathology compromising the passive stability of the hip joint, including acetabular labral injury, may lead to increased femoral head translation, greater joint contact pressures and ultimately degenerative hip disease. Activation of hip muscles may play an important role in augmenting the stability in the normal and the passively unstable hip. Research at other joints suggests that the local, rather than global, muscles are well suited to provide subtle joint compression, limiting translation, with minimal metabolic cost. Based on the known characteristics of local muscles and the limited research available on hip muscles, it is proposed that the local hip muscles; quadratus femoris, gluteus minimus, gemelli, obturator internus and externus, iliocapsularis and the deep fibres of iliopsoas, may be primary stabilisers of the hip joint. Interventions aimed at restoring isolated neuromuscular function of the primary hip stabilisers may be considered when treating people with passive hip instability prior to commencing global muscle rehabilitation. Finally, further research is needed to investigate the potential association between function of the hip muscles (including muscles likely to have a role in stabilising the hip) and hip pathology affecting hip stability such as acetabular labral lesions.

Distinct relationships of intramuscular and subcutaneous fat with cortical bone: findings from a cross-sectional study of young adult males and females.

CONTEXT: Intracellular fat within muscle and visceral tissue has been suggested to adversely influence bone development. OBJECTIVE: The aim of the study was to evaluate associations between im fat, as reflected by muscle density as measured by peripheral quantitative computed tomography, and cortical bone parameters in young adults. DESIGN/SETTING/PARTICIPANTS: We conducted a cross-sectional analysis of 1703 males and 2243 females aged 17.8 years from the Avon Longitudinal Study of Parents and Children. OUTCOME MEASURES: We measured cortical bone parameters from midtibial peripheral quantitative computed tomography scans. RESULTS: Muscle density (inversely related to im fat) was inversely associated with periosteal circumference (PC) (beta = -0.07 [95% confidence interval (CI), -0.1, -0.04]), cortical bone mineral density (BMDC) (beta = -0.21 [95% CI, -0.26, -0.17]), and cortical thickness (CT) (beta = -0.37 [95% CI, -0.42, -0.33]) (males and females combined, adjusted for age, height, gender, and muscle cross-sectional area). In contrast, sc fat area was positively associated with PC (beta = 0.10 [95% CI, 0.07, 0.12]), but no association was seen with BMDC or CT. To examine the role of candidate intermediary metabolic pathways, analyses were repeated after adjustment for insulin, C-reactive protein, and ß-C-telopeptides of type I collagen. Whereas similar associations were observed after adjustment for insulin and C-reactive protein, the association between muscle density and BMDC was partially attenuated by adjustment for ß-C-telopeptides of type I collagen (beta = -0.14 [95% CI, -0.20, -0.08]). CONCLUSION: Although im and sc fat were both positively associated with cortical bone mass, the nature of these relationships differed in that im fat was predominantly associated with CT and BMDC, whereas sc fat was mainly associated with PC. These relationships were largely independent of candidate metabolic pathways, such as altered bone resorption, insulin resistance, or inflammation.