Impaired Lumbar Extensor Force Control Is Associated with Increased Lifting Knee Velocity in People with Chronic Low-Back Pain.

The ability of the lumbar extensor muscles to accurately control static and dynamic forces is important during daily activities such as lifting. Lumbar extensor force control is impaired in low-back pain patients and may therefore explain the variances in lifting kinematics. Thirty-three chronic low-back pain participants were instructed to lift weight using a self-selected technique. Participants also performed an isometric lumbar extension task where they increased and decreased their lumbar extensor force output to match a variable target force within 20-50% lumbar extensor maximal voluntary contraction. Lifting trunk and lower limb range of motion and angular velocity variables derived from phase plane analysis in all planes were calculated. Lumbar extensor force control was analyzed by calculating the Root-Mean-Square Error (RMSE) between the participants' force and the target force during the increasing (RMSEA), decreasing (RMSED) force portions and for the overall force error (RMSET) of the test. The relationship between lifting kinematics and RMSE variables was analyzed using multiple linear regression. Knee angular velocity in the sagittal and coronal planes were positively associated with RMSEA (R2 = 0.10, ß = 0.35, p = 0.046 and R2 = 0.21, ß = 0.48, p = 0.004, respectively). Impaired lumbar extensor force control is associated with increased multiplanar knee movement velocity during lifting. The study findings suggest a potential relationship between lumbar and lower limb neuromuscular function in people with chronic low-back pain.

Assessment of Cardiometabolic Health, Diet and Physical Activity in Helicopter Rescue Paramedics.

Objective: Shift work is an established risk factor for weight gain, cardiovascular disease, Type II diabetes mellitus, and impaired health-related quality of life (HRQoL). Prolonged exposure to shift work is common in paramedics and other emergency medical service (EMS) providers. Sub-populations of EMS workers may have varying health outcomes when exposed to shift work, but the reasons for this have not been investigated. We sought to describe cardiometabolic health, dietary patterns, physical activity, and health-related quality of life (HRQoL) in a sample of experienced intensive care flight paramedics (ICFPs) working for a Helicopter Emergency Medical Service (HEMS).Methods: Fifteen paramedics (median age 45, IQR 42-48 years) were recruited to undertake a range of health assessments. These included a food frequency questionnaire to assess dietary patterns, sampling of biomarkers to determine cardiometabolic health risk, maximal aerobic capacity assessment via treadmill running and assessment of HRQoL via the SF-36 survey. In an extension of the study protocol, ten of the fifteen participants wore a physical activity monitor for one year.Results: Median (IQR) weight was 79.9 (72.3-89.3) kg, body fat percentage 23.3 (21.9-26.5) %, body mass index (BMI) 25.1 (21.9-27.4) kg.m2, and waist to height ratio 0.48 (0.45-0.54). Dietary analyses showed high discretionary food intake. Biomarkers of cardiometabolic health risk were all within normal range. HRQoL was 86.2/100 for physical health and 85.1/100 for mental health. V̇O2max was 47.0 (43.0-54.6) mL.kg-1.min-1. The ten participants that wore activity monitors completed 11,235 (8334-15,380) steps per day and undertook 50 (12-98) minutes per day/350 (84-686) minutes per week of moderate to vigorous physical activity. The least amount of physical activity was conducted on day shifts.Conclusions: For ICFPs included in this study, HRQoL, cardiometabolic and physical activity outcomes are representative of good health. Although shift work influences the amount of physical activity, ICFPs exceeded minimum recommendations even when rostered to duty. Despite lengthy careers in EMS, ICFPs demonstrate an excellent health profile that is likely due to high physical activity levels and healthy BMI. This information may be useful in guiding health interventions in the wider EMS workforce.

Cardiometabolic, Dietary and Physical Health in Graduate Paramedics during the First 12-Months of Practice - A Longitudinal Study.

Objective: Shift work is an established risk factor for poor health yet is necessary for paramedics to provide continuous care to the public. It is unknown how early into a career shift work may begin to impact health. This study sought to identify changes in cardiometabolic health, diet, aerobic capacity, physical activity and health-related quality of life (HRQoL) in graduate paramedics during the first 12-months of their career.Methods: Fifty-six paramedics with no history of regular shift work (28 female, 28 male; median age 24.5, IQR 23-26 years) were recruited for this study. Dietary patterns (food frequency questionnaires) and HRQoL (36-Item Short Form Questionnaire) were assessed at baseline, 6- and 12-months. Body weight, body mass index (BMI) and blood samples (fasting lipids, glucose, insulin and C-reactive protein) were measured at baseline and 12-months to ascertain cardiometabolic health risk. A subset of participants (n = 19; 10 female, 9 male) wore a physical activity monitor for 12 months and completed baseline and 12-month maximal aerobic capacity assessments (V̇O2max).Results: Body weight and BMI decreased in males and increased in females (-0.7% versus 1.7%, p = 0.02). HRQoL and dietary intake did not change over 12-months, except for a small decrease in fat intake (-1%). Consumption of core/healthy foods was lower than recommended at all timepoints. Biomarkers of cardiometabolic health were within normal range and did not change over 12-months, excepting insulin where a small non-significant increase was seen (+0.5 mIU/L, p = 0.61). Baseline V̇O2max was 41.4 (37.1-49.1) ml.kg-1.min-1, with no change noted at 12-months. Comparison of quarterly physical activity data showed no difference in steps per day (p = 0.47) or moderate to vigorous physical activity (MVPA, p = 0.92) across the 12-months. Paramedics completed less MVPA on day shifts compared to rostered days off (-14.68 minutes, p = 0.04).Conclusions: Dietary patterns, HRQoL, cardiometabolic health, aerobic capacity and physical activity levels did not change meaningfully in the first year of practice. Some dietary behaviors and physical activity levels could be improved and may mitigate health effects of exposure to shift work. Long-term follow-up of this group may aid in developing programs to enhance health for paramedics and other health workers.

The physiological demands of helicopter winch rescue in water and over land.

Physically demanding water and over land winch rescues are critical tasks for helicopter paramedics. To assess the physiological demands of winch rescue, 14 intensive care flight paramedics (12 male, 2 female, mean (±SD) age 44.3 (±5.4) years, experience 7.1 (±5.2) years) completed land and water-based task simulations. For the land task, VO2 was 41.7 (±4.5) mL kg-1 min-1, or 86 (±11) % of VO2peak. Task duration was 7.0 (±3.6) min, or 53 (±27) % of maximal acceptable work duration (MAWD) (13.2 (±9.0) min). For the water task, VO2 was 36.7 (±4.4) mL kg-1 min-1, (81 (±12) % of VO2peak). Water task duration was 10.2 (±1.1) min, or 47.6 (±4.8) % of calculated MAWD (21.0 (±15.6) min). These results demonstrate that helicopter rescue paramedics work at very high physiological workloads for moderate durations, and these demands should be considered when developing selection tests and when deploying to rescues, to ensure staff are capable of task performance. Practitioner summary: Paramedics performed helicopter winch rescue task simulations in water and over land. Paramedics worked at 81% of VO2peak for 10.2 min and 86% of VO2peak for 7 min for swim and land tasks respectively. Rescue organisations should consider these demands when selecting and credentialing staff and when deploying to incidents. Abbreviations: HEMS: helicopter emergency medical service; ICFP: intensive care flight paramedic; MAWD: maximal acceptable work duration; PES: physical employment standards; SAR: search and rescue.

Pain Induced Changes in Brain Oxyhemoglobin: A Systematic Review and Meta-Analysis of Functional NIRS Studies.

BACKGROUND: Neuroimaging studies show that nociceptive stimuli elicit responses in an extensive cortical network. Functional near-infrared spectroscopy (fNIRS) allows for functional assessment of changes in oxyhemoglobin (HbO), an indirect index for cortical activity. Unlike functional magnetic resonance imaging (fMRI), fNIRS is portable, relatively inexpensive, and allows subjects greater function. No systematic review or meta-analysis has drawn together the data from existing literature of fNIRS studies on the effects of experimental pain on oxyhemoglobin changes in the superficial areas of the brain. OBJECTIVES: To investigate the effects of experimental pain on brain fNIRS measures in the prefrontal-cortex and the sensory-motor-area; to determine whether there is a difference in oxyhemodynamics between the prefrontal-cortex and sensory-motor-area during pain processing; to determine if there are differences in HbO between patients with centralized persistent pain and healthy controls. METHODS: Studies that used fNIRS to record changes in oxyhemodynamics in prefrontal-cortex or sensory-motor-cortex in noxious and innoxious conditions were included. In total, 13 studies were included in the meta-analysis. RESULTS: Pain has a significantly greater effect on pre-frontal-cortex and sensory-motor areas than nonpainful stimulation on oxyhemodynamics. The effect of pain on sensory-motor areas was greater than the effect of pain on the prefrontal-cortex. There was an effect of centralized pain in the CPP group on oxyhemodynamics from a noxious stimulus compared to control's response to pain. CONCLUSIONS: Pain affects the prefrontal and sensory-motor cortices of the brain and can be measured using fNIRS. Implications of this study may lead to a simple and readily accessible objective measure of pain.

Comparison of swimming versus running maximal aerobic capacity in helicopter rescue paramedics.

Swimming is a critical task for helicopter rescue paramedics and aerobic capacity is assessed in this occupation to determine job suitability. We evaluated one treadmill-based and one pool-based assessment of maximal aerobic capacity (V̇O2peak) in 14 helicopter rescue paramedics. There was a small absolute difference (p = 0.11, d = 0.46) between V̇O2peak in the swim (45.5 ± 7.8 ml.kg-1.min-1) compared to the run (48.5 ± 5.5 ml.kg-1.min-1), with a moderate relationship noted (r = 0.74, 95% CI [0.35-, 0.91], p = 0.0023). Whilst not interchangeable, run V̇O2peak was a predictor of swim V̇O2peak. Maximal blood lactate was similar (p = 0.93) in swim (13.4 ± 3.8 mmol.L-1) and run (12.2 ± 3.0 mmol.L-1), and maximal heart rate 13% lower (p < 0.0001) in the swim (162 ± 11 bpm) versus the run (186 ± 10 bpm). To estimate swimming V̇O2peak in paramedics a treadmill test is sufficient but does not replace assessment of swimming proficiency. Practitioner Summary: We developed a swim protocol to assess maximal aerobic capacity in helicopter rescue paramedics. Compared to a treadmill-based test, our swim protocol generated 20% lower submaximal V̇O2 and 6% lower V̇O2peak. Although not interchangeable, a treadmill V̇O2peak test is indicative of maximal aerobic capacity in rescue paramedics whilst swimming. Abbreviations: HEMS: helicopter emergency medical service; PES: physical employment standards; ICFP: intensive care flight paramedic; RPE: rating of perceived exertion.

Muscular Coordination of Single-Leg Hop Landing in Uninjured and Anterior Cruciate Ligament-Reconstructed Individuals.

This study compared lower-limb muscle function, defined as the contributions of muscles to center-of-mass support and braking, during a single-leg hopping task in anterior cruciate ligament-reconstructed (ACLR) individuals and uninjured controls. In total, 65 ACLR individuals and 32 controls underwent a standardized anticipated single-leg forward hop. Kinematics and ground reaction force data were input into musculoskeletal models to calculate muscle forces and to quantify muscle function by decomposing the vertical (support) and fore-aft (braking) ground reaction force components into contributions by individual lower-limb muscles. Four major muscles, the vasti, soleus, gluteus medius, and gluteus maximus, were primarily involved in support and braking in both ACLR and uninjured groups. However, although the ACLR group demonstrated lower peak forces for these muscles (all Ps < .001, except gluteus maximus, P = .767), magnitude differences in these muscles' contributions to support and braking were not significant. ACLR individuals demonstrated higher erector spinae (P = .012) and hamstrings forces (P = .085) to maintain a straighter, stiffer landing posture with more forward lumbar flexion. This altered landing posture may have enabled the ACLR group to achieve similar muscle function to controls, despite muscle force deficits. Our findings may benefit rehabilitation and the development of interventions to enable faster and safer return to sport.

Greater knee flexion excursion/moment in hopping is associated with better knee function following anterior cruciate ligament reconstruction.

PURPOSE: Individuals with impaired knee function after anterior cruciate ligament reconstruction (ACLR) may be at greater risk of developing knee osteoarthritis related to abnormal knee joint movement and loading. The aim of this study was to assess the association between knee biomechanics and knee laxity during hopping and clinically assessed knee function (i.e., patient-reported knee function and hop tests) following ACLR. METHODS: Sixty-six participants (23 women, mean age 28 ± 6 years, mean 18 ± 3 months following ACLR) completed a standardized single-leg hopping task. Three-dimensional movement analysis was used to assess knee flexion excursion and body weight/height normalized knee flexion moments during landing for the involved limb. Anterior-posterior knee laxity was assessed with a KT-1000 knee arthrometer. Participants then completed a patient-reported knee function questionnaire and three separate hop tests (% of uninvolved limb) and were divided into poor and satisfactory knee function groups (satisfactory: ≥85% patient-reported knee function and ≥ 85% hop test symmetry). Associations between knee function and hop biomechanics/knee laxity were assessed using logistic regression and interquartile range scaled odds ratios (ORIQR). RESULTS: Greater knee flexion excursion (ORIQR 2.9, 95%CI 1.1-7.8), greater knee flexion moment (ORIQR 4.9, 95%CI 1.6-14.3) and lesser knee laxity (ORIQR 4.7, 95%CI 1.5-14.9) were significantly associated with greater odds of having satisfactory knee function (≥ 85% patient-reported knee function and ≥ 85% hop test symmetry). CONCLUSION: Greater knee flexion excursion/moment during hop-landing and lesser knee laxity is associated with better patient-reported knee function and single-leg hop test performance following ACLR. Patients with lower levels of knee function following ACLR demonstrated hop-landing biomechanics previously associated with early patellofemoral osteoarthritis. Therefore, interventions aimed at improving hop landing biomechanics in people with poor knee function are likely required. LEVEL OF EVIDENCE: III, Cross-sectional study.

Musculoskeletal injury profiles in professional Women's Tennis Association players.

OBJECTIVE: The physical demands of professional tennis combined with high training/match loads can contribute to musculoskeletal injury. The objectives of this study were to (1) describe the type, location and severity of injuries sustained during a 12-month tennis season in a cohort of professional female tennis players on the Women's Tennis Association (WTA) tour and (2) prospectively investigate associations between training/match loads and injury. METHODS: 52 WTA players competing at the Australian Open (2015) consented to participate. Injuries reported to WTA medical staff were classified using tennis-specific guidelines. Individual match exposure data were collected for all matches played at international level in 2015 and expressed per 1000 hours of WTA competition matchplay (MP) and 1000 match exposures (MEs). Variables associated with the number of injuries in the season and loss of time from competition were identified with regression analysis. RESULTS: The injury incidence rate (IR) was 56.6 (95% CI: 49.5 to 64.6) per 1000 hours of MP or 62.7 (95% CI: 54.8 to 71.6) per 1000 MEs, although the IR of injuries resulting in loss of time from competition was lower (12.8 per 1000 hours of MP, 92 injuries/100 players). Lower limb (51%) and muscle/tendon (50%) injuries were the most common site and type of injury. Common specific injury site subcategories were the thigh, shoulder/clavicle, ankle and knee in order of frequency. Various measures of match load were significantly associated with injury. CONCLUSION: This study prospectively analysed injury profiles, including severity across an entire season of professional tennis, and investigated the relationship between training/match loads and injury. These data may help medical professionals develop injury risk identification and prevention programmes.

Three-dimensional assessment of squats and drop jumps using the Microsoft Xbox One Kinect: Reliability and validity.

The Microsoft Xbox One Kinect™ (Kinect V2) contains a depth camera that can be used to manually identify anatomical landmark positions in three-dimensions independent of the standard skeletal tracking, and therefore has potential for low-cost, time-efficient three-dimensional movement analysis (3DMA). This study examined inter-session reliability and concurrent validity of the Kinect V2 for the assessment of coronal and sagittal plane kinematics for the trunk, hip and knee during single leg squats (SLS) and drop vertical jumps (DVJ). Thirty young, healthy participants (age = 23 ± 5yrs, male/female = 15/15) performed a SLS and DVJ protocol that was recorded concurrently by the Kinect V2 and 3DMA during two sessions, one week apart. The Kinect V2 demonstrated good to excellent reliability for all SLS and DVJ variables (ICC ≥ 0.73). Concurrent validity ranged from poor to excellent (ICC = 0.02 to 0.98) during the SLS task, although trunk, hip and knee flexion and two-dimensional measures of knee abduction and frontal plane projection angle all demonstrated good to excellent validity (ICC ≥ 0.80). Concurrent validity for the DVJ task was typically worse, with only two variables exceeding ICC = 0.75 (trunk and hip flexion). These findings indicate that the Kinect V2 may have potential for large-scale screening for ACL injury risk, however future prospective research is required.