Mechanical energy flow analysis in athletes with and without anterior cruciate ligament reconstruction during single-leg drop landing.

Techniques that reduce mechanical energy have been linked to lower chances of experiencing an Anterior Cruciate Ligament (ACL) injury. Although there is evidence that movement patterns are altered in athletes who have undergone Anterior Cruciate Ligament Reconstruction (ACLR), energy transfer mechanisms have not been examined. This study aimed to compare energy flow mechanisms during single-leg drop landing between athletes with and without history of ACLR. A total of 20 female athletes were included in this study. Ten participants underwent ACLR 12 months ago (mean age, 21.57 ± 0.41 years) and 10 were healthy controls (mean age, 20.89 ± 0.21 years). Participants executed the single-leg drop landing (SLL) maneuver by descending from a 30 cm wooden box and landing on the tested leg on an embedded force plate. Information collected during the SLL trials was refined using rigid-body analysis and inverse dynamics within Nexus software, ultimately allowing construction of skeletal models of the athletes. Ankle and knee mechanical energy expenditure (MEE) was higher in the control participants during landing. However, the result for the hip MEE demonstrated that MEE of the control group was significantly lower compared with the ACLR group, but MEE of the control subjects was higher as compared to ACLR group (p ˂ 0.05). Results suggest the avoidant use of the quadriceps muscle post ACLR leads to knee-avoidant mechanics and loss of knee joint power generation during a SLL task.

Association between physical activity and body posture: a systematic review and meta-analysis.

OBJECTIVE: To estimate the possible associations between posture and physical activity (PA). DESIGN: A systematic review and meta-analysis. DATA SOURCES: The search was conducted in seven databases (PubMed, Web of Science, SportDiscus, EMBASE, Scopus, Cochrane Library, and CINAHL) for studies published from inception to January 2023. ELIGIBILITY CRITERIA FOR SELECTING STUDIES: Studies were required to meet following criteria: (1) study design: cross-sectional, case control and cohort studies. (2) Participants: people of all ages without any diagnosed diseases. (3) Exposure and outcome: studies that examined the possible effect or correlations between PA, physical inactivity, physical exertion and human body posture. RESULTS: Sixteen cross-sectional studies, two cohort studies and one case control study involving a total of 16772 participants aged from 6 to 79 years were included. Correlational studies showed that there was a significant relationship between PA and posture (C = 0.100, CI 95% = 0.012-0.186). However, regression studies demonstrated that there was not a significant association between PA and posture (C = 1.00, CI 95% = 0.998-1.002). Three studies investigated the association between PA and the lumbar lordosis and showed that there was not a significant association between the lordosis and PA (CI 95%: -0.253-0.048, P = 0.180). In addition, four studies showed that there were not any associations between scoliosis and PA (CI 95%: 0.819, 1.123, P = 0.607). The evidence of heterogeneity and publication bias was found among all analyzed data (P < 0.05). Also, meta regression was used for age and BMI and the results were not significant. CONCLUSION: Although a weak correlation was shown to exist between PA and human posture, the odds ratio indicated that there was not a significant association between PA and human posture. The lack of a significant relationship may indicate that multiple biopsychosocial factors may be involved in human posture. In summary, our study highlights the need for caution when interpreting the results of meta-analyses, particularly when there is significant heterogeneity and publication bias in the included studies.

Are clinical outcomes associated with baseline sensory profiles in people with musculoskeletal shoulder pain? Protocol for a prospective longitudinal observational study.

BACKGROUND: Musculoskeletal shoulder pain is a common problem and its symptoms often become persistent. The experience of pain is multidimensional, and therefore, a range of patient characteristics may influence treatment response. An altered sensory processing has been associated with persistent musculoskeletal pain states and may contribute to outcomes in patients with musculoskeletal shoulder pain. The presence and potential impact of altered sensory processing in this patient cohort is not currently known. The aim of this prospective longitudinal cohort study is to investigate if baseline sensory characteristics are associated with clinical outcomes in patients presenting to a tertiary hospital with persistent musculoskeletal shoulder pain. If found, a relationship between sensory characteristics and outcome may lead to the creation of more effective treatment strategies and improvements in risk adjustment and prognosis. METHODS: This is a single-centre prospective cohort study with 6-, 12- and 24-month follow-up. A total of 120 participants aged ≥18 years with persistent musculoskeletal shoulder pain (≥3 months) will be recruited from an Australian public tertiary hospital orthopaedic department. Baseline assessments, including quantitative sensory tests and a standardised physical examination, will be performed. In addition, information will be obtained from patient interviews, self-report questionnaires and medical records. Follow-up outcome measures will comprise information from the Shoulder Pain and Disability Index and a six-point Global Rating of Change scale. ANALYSIS: Descriptive statistics will be used to report baseline characteristics and outcome measures over time. Change in outcome measures at the primary endpoint of six months from baseline will be calculated using paired t-tests. Associations between baseline characteristics and outcomes at a 6-month follow-up will be reported using multivariable linear and logistic regression models. DISCUSSION: Understanding the relationship between sensory profile and the variable response to treatment in people with persistent musculoskeletal shoulder pain may enhance our understanding of the mechanisms contributing to the presentation. In addition, through better understanding of the contributing factors, the results of this study may contribute to the development of an individualised, patient-centred approach to treatment for people with this highly prevalent and debilitating condition.

The association between size and symmetry of the lumbar multifidus muscle, and injuries in adolescent rugby union players.

OBJECTIVES: This study aimed to investigate the association between size and symmetry of the lumbar multifidus muscle, and season injuries in adolescent rugby union players. DESIGN: Prospective longitudinal cohort study. SETTING: Pre-season assessment of the size (cross-sectional area) of the lumbar multifidus (L2-5) muscles using ultrasound imaging. PARTICIPANTS: Seventy-one adolescent rugby union players (aged 15-18 years). MAIN OUTCOME MEASURES: "Time-loss" injuries were recorded during the season and divided into four injury regions (head and neck, upper limb, trunk and lower limb). RESULTS: Thirty-nine injuries were recorded during the season. Players who sustained an upper limb injury during the season had smaller lumbar multifidus muscles at the L5 vertebral level (effect size = 0.7, p = 0.03) and asymmetry in muscle size at the L2 (p = 0.05) and L5 (p = 0.04) in the pre-season. There was no association between size of the lumbar multifidus muscle and other injuries (p > 0.05). CONCLUSION: Lumbar multifidus muscle size and symmetry may impact lumbopelvic control which may increase the risk of sustaining an upper limb injury during rugby union. Future research should aim to identify whether lumbar multifidus muscle size is a modifiable risk factor for rugby union injuries to guide future intervention programs.

Physiotherapy practices when treating patients with COVID-19 during a pandemic: A survey study.

Background Specific details pertaining to the clinical and other challenges faced by physiotherapists managing patients with COVID-19 during the pandemic are still largely unknown. Objectives To determine how physiotherapists clinically managed patients with COVID-19 in a hospital-based setting during the pandemic and to identify the personal and professional effects of working as a physiotherapist at this time. Methods Self-administered electronic cross-sectional survey. Participants included physiotherapists from around the world involved in the clinical management of patients with COVID-19. Results Of the 204 participants who returned the questionnaire, 39% worked as senior physiotherapists, 29% as consultant or specialist physiotherapists, 23% as general physiotherapists and 4% as graduate physiotherapists. Seventy-two percent of participants worked in the intensive care unit. The largest barrier to treating patients with COVID-19 was a lack of intensive care trained physiotherapists (70%). Eighty-three percent of participants reported performing activities outside of their typical work duties, including proning patients (55%), tutoring and advising other staff in the intensive care unit (55%) and adjusting or changing ventilator settings (52%). Almost all participants (90%) reported being aware of physiotherapy specific guidelines for treating patients with COVID-19, yet most participants performed techniques that were not recommended. Conclusions The experience of the pandemic highlighted the need for specialist training and availability of experienced cardiorespiratory physiotherapists to manage patients with COVID-19, specifically in intensive care. Furthermore, clear guidelines on the management of patients with COVID-19 should be established to ensure optimal management of patients and ensure the safety of physiotherapy staff.

Evaluation of the vestibular/ocular motor screening assessment in active combat sport athletes: an exploratory study.

OBJECTIVE: The first aim of this study was to compare the results of the vestibular/ocular motor screening (VOMS) in combat sport athletes with a healthy control population. Second, to explore differences between athletes with and without a concussion history. Third, to examine the relationship between VOMS and the Post-Concussion Symptom Scale (PCSS) in combat sport athletes. PARTICIPANTS: Forty active male combat sport athletes and 40 healthy male control participants were recruited from 4 clubs and a University in Australia. METHODS: Participants completed the VOMS in a primary care physiotherapy clinic. Participants completed an injury questionnaire and the PCSS. RESULTS: An "abnormal" score in at least one subtest or near point convergence (NPC) was recorded in 45% of the combat group compared with 22.5% of the control group. All VOMS scores and NPC distance were greater in the combat group compared with control group (p < 0.05). The VOMS scores were found to be moderately positively correlated with the PCSS. There was no difference in VOMS between athletes with and without a history of concussion (p > 0.05). CONCLUSION: VOMS scores differed between combat sport athletes and control participants. The PCSS may aid clinicians in identifying athletes who have underlying vestibular/oculomotor impairment.

The Effects of Reconditioning Exercises Following Prolonged Bed Rest on Lumbopelvic Muscle Volume and Accumulation of Paraspinal Muscle Fat.

Reduced muscle size and accumulation of paraspinal muscle fat content (PFC) have been reported in lumbopelvic muscles after spaceflights and head-down tilt (HDT) bed rest. While some information is available regarding reconditioning programs on muscle atrophy recovery, the effects on the accumulation of PFC are unknown. Recently, a device (the Functional Re-adaptive Exercise Device-FRED) has been developed which aims to specifically recruit lumbopelvic muscles. This study aimed to investigate the effects of a standard reconditioning (SR) program and SR program supplemented by FRED (SR + FRED) on the recovery of the lumbopelvic muscles following 60-day HDT bed rest. Twenty-four healthy participants arrived at the facility for baseline data collection (BDC) before the bed rest period. They remained in the facility for 13-day post-HDT bed rest and were randomly allocated to one of two reconditioning programs: SR or SR + FRED. Muscle volumes of the lumbar multifidus (LM), lumbar erector spinae (LES), quadratus lumborum (QL), and psoas major (PM) muscles were measured from axial T1-weighted magnetic resonance imaging (MRI) at all lumbar intervertebral disc levels. PFC was determined using a chemical shift-based lipid/water Dixon sequence. Each lumbopelvic muscle was segmented into four equal quartiles (from medial to lateral). MRI of the lumbopelvic region was conducted at BDC, Day-59 of bed rest (HDT59), and Day-13 after reconditioning (R13). Comparing R13 with BDC, the volumes of the LM muscle at L4/L5 and L5/S1, LES at L1/L2, and QL at L3/L4 had not recovered (all-p < 0.05), and the PM muscle remained larger at L1/L2 (p = 0.001). Accumulation of PFC in the LM muscle at the L4/L5 and L5/S1 levels remained higher in the centro-medial regions at R13 than BDC (all-p < 0.05). There was no difference between the two reconditioning programs. A 2-week reconditioning program was insufficient to fully restore all volumes of lumbopelvic muscles and reverse the accumulation of PFC in the muscles measured to BDC values, particularly in the LM muscle at the lower lumbar levels. These findings suggest that more extended reconditioning programs or alternative exercises may be necessary to fully restore the size and properties of the lumbopelvic muscles after prolonged bed rest.

Nordic strength and history of hamstring injury in Australian Football League players.

OBJECTIVES: Compare hamstring strength between Australian Football League (AFL) players with and without a prior hamstring injury and determine the effect of the number of previous hamstring injuries, time since the last injury, and injury severity, on hamstring strength. DESIGN: Cross-sectional, retrospective. SETTING: AFL clubs. PARTICIPANTS: 124 AFL players. MAIN OUTCOME MEASURES: Bilateral hamstring strength was assessed on a Nordbord (Vald Performance) during the Nordic Hamstring Exercise. Self-reported questionnaires were used to record previous hamstring injuries. Players were categorized into No Injury or Hamstring Injury groups. Previously injured players were subgrouped based on number of prior hamstring injuries (single or multiple), time since the last hamstring injury (≤1 or > 1-year ago), and hamstring injury severity (≤3 or > 3 matches missed). RESULTS: 19 hamstring injuries were reported. Hamstring strength was not different between players with and without a history of hamstring injury when assessed in absolute (N) or relative (i.e., N.kg-1) terms. No differences in strength were detected between hamstring injury subgroups when assessed in absolute or relative terms. CONCLUSIONS: AFL players that experienced a previous hamstring injury did not exhibit deficits in hamstring strength relative to their uninjured limb or players without a previous hamstring injury.

Effect of Motor Control Training on Trunk Muscle Morphometry, Pain, and Disability in People With Chronic Low Back Pain: A Systematic Review and Meta-Analysis.

OBJECTIVE: The aim of this systematic review and meta-analysis was to study the effects of motor control training (MCT) on trunk muscle morphometry measured by ultrasound imaging and pain and disability in individuals with chronic low back pain. METHODS: PubMed, Web of Science, Scopus, and Cochrane Library databases were searched from study inception until January 2021. Randomized control trials evaluating both muscle morphometry and pain or disability in individuals with chronic low back pain were included. Study selection, data extraction, and quality assessment were performed by 2 reviewers independently. Modified Downs and Black tool and the Grading of Recommendations Assessment, Development and Evaluation approach were used to assess the risk of bias and quality of evidence, respectively. A meta-analysis was performed using a random effects model with mean difference or standardized mean difference (SMD). RESULTS: Of 3459 studies initially identified, 15 studies were included, and 13 studies were selected for meta-analysis. The results revealed no differences in the resting thickness of the transversus abdominis, internal and external oblique, and lumbar multifidus muscles in studies that compared MCT with other interventions. The transversus abdominis muscles contraction ratio was greater (SMD = 0.93; 95% confidence interval [CI], -0.0 to 1.85) and lower pain (weighted mean difference: -1.07 cm; 95% CI, -1.91 to -0.22 cm; P = .01) and disability (SMD = -0.86; 95% CI, -1.42 to -0. 29; P < .01) scores were found in the groups who underwent MCT compared with other interventions. CONCLUSION: This systematic review and meta-analysis found that motor control exercise training increased the transverse abdominis contraction ratio (muscle activation) and improved the level of pain and disability compared to other interventions in people with chronic low back pain. However, motor control exercise training was not superior to other interventions in increasing the resting thickness of deep abdominal and lumbar multifidus muscles in intervention times less than 12 weeks.

Cervical spine characteristics differ in competitive combat athletes compared with active control participants.

BACKGROUND: Injury to the head and neck are common in combat sport athletes. Impairments of the cervical spine have been found in some athletes who participate in sports with high forces and collisions. There is a lack of research on the effects of combat sports on the cervical spine. OBJECTIVE: The primary study aim was to investigate differences in cervical spine characteristics between combat athletes and a similarly aged active control group. The secondary aim was to investigate the relationship between symptom-based outcome measures and characteristics of the cervical spine. DESIGN: Cross-sectional. METHOD: 40 male adult combat sport athletes and 40 male adult control participants were recruited from 4 combat sport clubs and a university campus, Australia. Cervical spine assessments were conducted at a private physiotherapy clinic. The Neck Disability Index and the Post-Concussion Symptom Scale were used as symptom-based outcome measures. RESULTS: Combat sport athletes had a reduced range of cervical motion, but greater isometric strength and endurance compared with a control group (p < 0.05). The Neck Disability Index and Post-Concussion Symptom Scale were negatively correlated with cervical spine range of motion and isometric strength, meaning that higher scores correlated with a reduction in function. CONCLUSIONS: Differences were observed in characteristics of the cervical spine in combat sport athletes compared with a control group. Higher symptom-based outcome scores correlated with reduced range of motion and strength of cervical spine muscles. Further investigation to establish clinical cut-off scores for functional impairment may be warranted.

Relationship between the morphology and composition of the lumbar paraspinal and psoas muscles and lumbar intervertebral motion in chronic low-back pain: An exploratory study.

Muscles of the lumbar spine play an important role in controlling segmental intervertebral motion. This study aimed to evaluate the association between lumbar intervertebral motion and changes in lumbar morphology/composition in people with chronic low-back pain (CLBP). A sample of 183 patients with CLBP participated in this cross-sectional study. Participants underwent lumbar flexion-extension X-rays to determine vertebral motion (translational and/or rotational motion) of lumbar levels (L1-L2 to L5-S1) and lumbar spine magnetic resonance imaging to quantify total and functional cross-sectional areas (CSAs) and asymmetry of the multifidus (MF), lumbar erector spinae (LES), and psoas muscles. The relationship between morphology/composition of the muscles and lumbar intervertebral motion was investigated. Smaller total and functional CSAs of the MF and greater CSAs of the LES muscle were observed in participants with greater intervertebral motion. Muscle asymmetry was observed at different lumbar vertebral levels. The greatest amount of translational intervertebral motion was observed at the L3-L4 level, while the greatest amount of rotational translation occurred at the L4-L5. Associations were observed between the morphology of the paraspinal muscles at the vertebral levels adjacent to the L3-L4 level and the increased intervertebral motion at this level. Relationships between measures of muscle morphology/composition and increased segmental vertebral motion were observed. The results may provide a plausible biological reason for the effectiveness of rehabilitating deficient paraspinal muscles in a subset of people with CLBP.

Vestibular and oculomotor function in male combat sport athletes.

OBJECTIVES: To investigate for differences in vestibulo-ocular function between active male combat sport athletes and a healthy control group. In addition, to explore the relationship between symptom-based outcome measures with vestibulo-ocular function. DESIGN: Cross-sectional. METHODS: 40 male adult combat sport athletes and 40 active male control participants were recruited from 4 martial arts schools and a University campus in Queensland, Australia. All participants completed a standardised protocol which was used to assess vestibulo-ocular function. The protocol included 3 components: 1) oculomotor function, 2) benign paroxysmal positional vertigo screening, and 3) vestibulo-ocular reflex function. The Post-Concussion Symptom Scale, Vestibular/Ocular Motor Screening tool and Dizziness Handicap Inventory were used as symptom-based outcome measures. RESULTS: More combat sport athletes had oculomotor abnormalities than control group participants. There were no between group differences in benign paroxysmal positional vertigo, vestibulo-ocular reflex function and the video-head impulse test gain (ms). Combat sport athletes had higher symptom-based outcome scores. The Vestibular/Ocular Motor Screening tool and Dizziness Handicap Inventory were found to have moderate positive relationships with the total number of abnormalities detected in the combat sport group. CONCLUSIONS: Vestibulo-ocular function is imperative for combat sport athletes to perform evasive manoeuvres and land their own strikes. The present study findings may aid clinicians in the identification of combat sport athletes with underlying vestibulo-ocular dysfunction, prompting further investigation.

Alteration of lumbar muscle morphology and composition in relation to low back pain: a systematic review and meta-analysis.

BACKGROUND CONTEXT: Previous studies have proposed that there is a relationship between low back pain (LBP) and morphology and composition of paraspinal muscles. However, results have been conflicting, especially regarding fatty infiltration of muscles. PURPOSE: The primary goal of this study was to review and analyze results from imaging studies which investigated morphological and composition changes in the multifidus, erector spinae and psoas major muscles in people with LBP. STUDY DESIGN/SETTING: Systematic review with meta-analysis. PATIENT SAMPLE: A patient sample was not required OUTCOME MEASURES: This review did not have outcome measures. METHODS: PubMed, Scopus, Web of Sciences, EMBASE and ProQuest were searched for eligible studies up to 31st July 2020 (all languages). A systematic search of electronic databases was conducted to identify studies investigating the association between the morphology and fat content of lumbar muscles in people with LBP compared with a (no LBP) control group. 13,795 articles were identified. Based on the screening for inclusion/ exclusion, 25 were included. The quality of the studies was evaluated using the Newcastle-Ottawa Scale. From the 25 articles, 20 were included in the meta-analysis. RESULTS: Results showed that the total cross-sectional area of the multifidus was smaller in people with LBP (Standardized mean difference, SMD = -0.24, 95% CI = -0.5 to 0.03). Combined SMDs showed a medium effect of LBP on increasing multifidus muscle fat infiltration (SMD = 0.61, 95% CI = 0.30 to 0.91). There were no LBP related differences identified in the morphology or composition of the lumbar erector spine and psoas major muscles. CONCLUSIONS: People with LBP were found to have somewhat smaller multifidus muscles with a significant amount of intramuscular fat infiltration. Varying sample size, age and BMI of participants, quality of studies and the procedures used to measure fat infiltration are possible reasons for inconsistencies in results of previous studies.

Intramuscular lipid concentration increased in localized regions of the lumbar muscles following 60 day bedrest.

BACKGROUND CONTEXT: Prolonged bedrest induces accumulation of intramuscular lipid concentration (ILC) in the lumbar musculature; however, spatial distribution of ILC has not been determined. Artificial gravity (AG) mitigates some adaptations induced by 60 day bedrest by creating a head-to-feet force while participants are in a supine position. PURPOSE: To quantify the spatial distribution of accumulation of ILC in the lumbar musculature after 60 day bedrest, and whether this can be mitigated by AG exposure. STUDY DESIGN: Prospective longitudinal study. PATIENT SAMPLE: Twenty-four healthy individuals (8 females) participated in the study: Eight received 30 min continuous AG (cAG); Eight received 6 × 5 min AG (iAG), interspersed with rests; Eight were not exposed to AG (CRTL). OUTCOME MEASURES: From 3T magnetic resonance imaging (MRI), axial images were selected to assess lumbar multifidus (LM), lumbar erector spinae (LES), quadratus lumborum (QL), and psoas major (PM) muscles from L1/L2 to L5/S1 intervertebral disc levels. Chemical shift-based 2-echo lipid and/or water Dixon sequence was used to measure tissue composition. Each lumbar muscle was segmented into four equal quartiles (from medial to lateral). METHODS: Participants arrived at the facility for the baseline data collection before undergoing a 60 day strict 6° head-down tilt (HDT) bedrest period. MRI of the lumbopelvic region was conducted at baseline and Day-59 of bedrest. Participants performed all activities, including hygiene, in 6° HDT and were discouraged from moving excessively or unnecessarily. RESULTS: At the L4/L5 and L5/S1 intervertebral disc levels, 60-day bedrest induced a greater increase in ILC in medial and lateral regions (∼+4%) of the LM than central regions (∼+2%; p<.05). A smaller increase in ILC was induced in the lateral region of LES (∼+1%) at L1/L2 and L2/L3 than at the centro-medial region (∼+2%; p<.05). There was no difference between CRTL and intervention groups. CONCLUSIONS: Inhomogeneous spatial distribution of accumulation of ILC was found in the lumbar musculature after 60 day bedrest. These findings might reflect pathophysiological mechanisms related to muscle disuse and contribute to localized lumbar spine dysfunction. Altered spatial distribution of ILC may impair lumbar spine function after prolonged body unloading, which could increase injury risk to vulnerable soft tissues, such as the lumbar intervertebral discs. These novel results may represent a new biomarker of lumbar deconditioning for astronauts, bedridden, sedentary individuals, or those with chronic back pain. Changes are potentially modifiable but not by the AG protocols tested here.

Trunk muscle size and function in volleyball players with and without injuries to the head, neck and upper limb.

OBJECTIVE: To investigate trunk muscle size and function in elite and community volleyball players with and without a history of head, neck or upper limb injury. DESIGN: Cross-sectional observational study. SETTING: Volleyball training camp or training sessions. PARTICIPANTS: 86 volleyball players (elite = 29; community = 57). MAIN OUTCOME MEASURES: Information regarding history of head, neck or upper limb injuries was collected by self-report questionnaires. Trunk muscle size (multifidus, transversus abdominis, internal oblique and quadratus lumborum) and voluntary contraction (multifidus, transversus abdominis, internal oblique) were assessed using ultrasound imaging. RESULTS: For trunk muscle size, no significant differences were found between elite and community volleyball players with and without a history of injury (all p > 0.05). A significant difference was found for voluntary contraction of the multifidus and transversus abdominis muscles for elite and community volleyball players with and without a history of injury (all p < 0.05). CONCLUSION: A difference in trunk muscle contraction but no change in trunk muscle size in players with a history of head, neck or upper limb injuries may represent an altered muscle recruitment pattern rather than a deficiency in trunk muscle strength. Prospective studies are required to determine if these adaptations are compensatory (and protective) or predispose players to further injuries.

Sensorimotor system changes in adolescent rugby players post-concussion: A prospective investigation from the subacute period through to return-to-sport.

BACKGROUND: The pathophysiology of concussion is complex. Altered sensorimotor function post-concussion may contribute to the wide range of symptoms and impairments reported. There is currently limited evidence documenting changes in sensorimotor function during the recovery period. The aim of this study was to investigate the effect of concussion on the sensorimotor system in adolescents post-concussion using a multifaceted approach. STUDY DESIGN: Prospective nested case-control study. METHODS: A total of 285 male adolescent rugby players underwent assessment of sensorimotor function during preseason. Players who sustained a concussion during the season and control players, matched for age and playing position, were assessed in the subacute period (3-5 days) and after return-to-sport (3 weeks). Tests of sensorimotor function included balance, cervical spine and vestibulo-ocular function, and measurement of the size and contraction of lumbopelvic muscles (ultrasound imaging). RESULTS: Twenty-three players (8%) sustained a concussion. Of these, 20 players were assessed during the subacute period and 17 players following return-to-sport. The prevalence of vestibulo-ocular dysfunction increased from 38.9% to 72.2% during the subacute period and dysfunction was present in 83.3% of players after return-to-sport (p = 0.01). Changes in lumbar multifidus muscle size (p = 0.002) and thickness (p = 0.05) at the L5 vertebral level were observed. No statistically significant changes in balance, cervical spine proprioception, or contraction of lumbopelvic muscles were found (p > 0.05). CONCLUSION: Changes in sensorimotor function were observed in the subacute period post-concussion, with some persisting after return-to-sport. Using symptom-based criteria for return-to-sport may not adequately reflect the sequelae of concussion on the sensorimotor system.

Gluteal Muscle Atrophy and Increased Intramuscular Lipid Concentration Are Not Mitigated by Daily Artificial Gravity Following 60-Day Head-Down Tilt Bed Rest.

Exposure to spaceflight and head-down tilt (HDT) bed rest leads to decreases in the mass of the gluteal muscle. Preliminary results have suggested that interventions, such as artificial gravity (AG), can partially mitigate some of the physiological adaptations induced by HDT bed rest. However, its effect on the gluteal muscles is currently unknown. This study investigated the effects of daily AG on the gluteal muscles during 60-day HDT bed rest. Twenty-four healthy individuals participated in the study: eight received 30 min of continuous AG; eight received 6 × 5 min of AG, interspersed with rest periods; eight belonged to a control group. T1-weighted Dixon magnetic resonance imaging of the hip region was conducted at baseline and day 59 of HDT bed rest to establish changes in volumes and intramuscular lipid concentration (ILC). Results showed that, across groups, muscle volumes decreased by 9.2% for gluteus maximus (GMAX), 8.0% for gluteus medius (GMED), and 10.5% for gluteus minimus after 59-day HDT bed rest (all p < 0.005). The ILC increased by 1.3% for GMAX and 0.5% for GMED (both p < 0.05). Neither of the AG protocols mitigated deconditioning of the gluteal muscles. Whereas all gluteal muscles atrophied, the ratio of lipids to intramuscular water increased only in GMAX and GMED muscles. These changes could impair the function of the hip joint and increased the risk of falls. The deconditioning of the gluteal muscles in space may negatively impact the hip joint stability of astronauts when reexpose to terrestrial gravity.

Intermittent short-arm centrifugation is a partially effective countermeasure against upright balance deterioration following 60-day head-down tilt bed rest.

This study investigated whether artificial gravity (AG), induced by short-radius centrifugation, mitigated deterioration in standing balance and anticipatory postural adjustments (APAs) of trunk muscles following 60-day head-down tilt bed rest. Twenty-four participants were allocated to one of three groups: control group (n = 8); 30-min continuous AG daily (n = 8); and intermittent 6 × 5 min AG daily (n = 8). Before and immediately after bed rest, standing balance was assessed in four conditions: eyes open and closed on both stable and foam surfaces. Measures including sway path, root mean square, and peak sway velocity, sway area, sway frequency power, and sway density curve were extracted from the center of pressure displacement. APAs were assessed during rapid arm movements using intramuscular or surface electromyography electrodes of the rectus abdominis; obliquus externus and internus abdominis; transversus abdominis; erector spinae at L1, L2, L3, and L4 vertebral levels; and deep lumbar multifidus muscles. The relative latency between the EMG onset of the deltoid and each of the trunk muscles was calculated. All three groups had poorer balance performance in most of the parameters (all P < 0.05) and delayed APAs of the trunk muscles following bed rest (all P < 0.05). Sway path and sway velocity were deteriorated, and sway frequency power was less in those who received intermittent AG than in the control group (all P < 0.05), particularly in conditions with reduced proprioceptive feedback. These data highlight the potential of intermittent AG to mitigate deterioration of some aspects of postural control induced by gravitational unloading, but no protective effects on trunk muscle responses were observed.NEW & NOTEWORTHY This study presents novel insights into the effect of artificial gravity (AG) on the deterioration of standing balance and anticipatory postural adjustments (APAs) of trunk muscles induced by 60-day strict head-down bed rest. The results indicated severe balance dysfunction and delayed APAs during rapid arm movement. AG partially mitigated the deterioration in standing balance and may thus be considered as a potential countermeasure for future planetary surface explorations. Optimization of AG protocols might enhance effects.

The prevalence and burden of recurrent headache in Australian adolescents: findings from the longitudinal study of Australian children.

BACKGROUND: Headache disorders are highly prevalent worldwide, but not well investigated in adolescents. Few studies have included representative nationwide samples. This study aimed to present the prevalence and burden of recurrent headache in Australian adolescents. METHODS: The prevalence of recurrent headache, headache characteristics (severity and frequency) and burden on health-related quality of life in Australian children aged 10-17 years were presented, using nationally representative data from the Longitudinal Study of Australian children (LSAC). The LSAC, commencing in 2004, collects data every 2 years from a sample of Australian children of two different age cohorts: B 'baby' cohort, aged 0-1 years and K 'kindergarten' cohort, aged 4-5 years at the commencement of the study. Face-to-face interviews and self-complete questionnaires have been conducted with the study child and parents of the study child (carer-reported data) at each data collection wave, with seven waves of data available at the time of the current study. Wave 7 of the LSAC was conducted in 2016, with B cohort children aged 12-13 years and K cohort children aged 16-17 years. For the current study, data were accessed for four out of seven waves of available data (Wave 4-7) and presented cross-sectionally for the two cohorts of Australian children, for the included age groups (10-11 years, 12-13 years, 14-15 years and 16-17 years). All available carer-reported questionnaire data pertaining to headache prevalence, severity and frequency, general health and health-related quality of life, for the two cohorts, were included in the study, and presented for male and female adolescents. Carer-reported general health status of the study child and health-related quality of life scores, using the parent proxy-report of the Paediatric Quality of Life Inventory™ 4.0, were compared for male and female adolescents with recurrent headache and compared with a healthy group. Finally, health-related quality of life scores were compared based on headache frequency and severity. RESULTS: The LSAC study initially recruited 10,090 Australian children (B cohort n = 5107, K cohort n = 4983), and 64.1% of the initial sample responded at wave 7. Attrition rates across the included waves ranged from 26.3% to 33.8% (wave 6 and 7) for the B cohort, and 16.3% to 38.0% (wave 4-7) for the K cohort. Recurrent headache was more common in females, increasing from 6.6% in 10-11 years old females to 13.2% in 16-17 years old females. The prevalence of headache in males ranged from 4.3% to 6.4% across the age groups. Health-related quality of life scores were lower for all functional domains in adolescents with recurrent headache, for both sexes. Headache frequency, but not severity, was significantly associated with lower health-related quality of life scores, in both males and females. CONCLUSIONS: Recurrent headache was common among Australian adolescents and increased in prevalence for females, across the age groups. Frequent recurrent headache is burdensome for both male and female adolescents. This study provides information regarding the prevalence and burden of recurrent headache in the adolescent population based on findings from the Longitudinal Study of Australian Children.

Lumbar muscle atrophy and increased relative intramuscular lipid concentration are not mitigated by daily artificial gravity after 60-day head-down tilt bed rest.

Exposure to axial unloading induces adaptations in paraspinal muscles, as shown after spaceflights. This study investigated whether daily exposure to artificial gravity (AG) mitigated lumbar spine flattening and muscle atrophy associated with 60-day head-down tilt (HDT) bed rest (Earth-based space analog). Twenty-four healthy individuals participated in the study: 8 received 30-min continuous AG; 8 received 6 × 5-min AG interspersed with rest periods; and 8 received no AG exposure (control group). Magnetic resonance imaging (MRI) of the lumbopelvic region was conducted at baseline (BDC) and at day 59 of HDT (HDT59). Longitudinal relaxation time (T1)-weighted images were used to assess morphology of the lumbar spine (spinal length, intervertebral disk angles, disk area) and volumes of the lumbar multifidus (LM), lumbar erector spinae (LES), quadratus lumborum (QL), and psoas major (PM) muscles from L1/L2 to L5/S1 vertebral levels. A chemical shift-based two-point lipid/water Dixon sequence was used to evaluate muscle composition. Results showed that spinal length and disk area increased (P < 0.05); intervertebral disk angles (P < 0.05) and muscle volumes of LM, LES, and QL reduced (P < 0.01); and lipid-to-water ratio for the LM and LES muscles increased (P < 0.01) after HDT59 in all groups. Neither of the AG protocols mitigated the lumbar spinae deconditioning induced by HDT bed rest. The increase in lipid-to-water ratio in LM and LES muscles indicates an increased relative intramuscular lipid concentration. Altered muscle composition in atrophied muscles may impair lumbar spine function after body unloading, which could increase injury risk to vulnerable soft tissues. This relationship needs further investigation.NEW & NOTEWORTHY This study presents novel insights into the morphological adaptations occurring in the lumbar spine after 60-day head-down bed rest and the potential role of artificial gravity (AG) to mitigate them. Results demonstrated no protective effect of AG protocols used in this study. In atrophied paraspinal muscles, the ratio of lipids versus intramuscular water increased in the postural lumbar muscles, which could impair muscle function during upright standing. These findings have relevance for future space explorations.