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OBJECTIVE: The project aimed to implement neuromuscular training during a full soccer and handball league season and to experimentally analyze the neuromuscular adaptation mechanisms elicited by this training during a standardized sidecutting maneuver known to be associated with non-contact anterior cruciate ligament (ACL) injury. DESIGN: The players were tested before and after 1 season without implementation of the prophylactic training and subsequently before and after a full season with the implementation of prophylactic training. PARTICIPANTS: A total of 12 female elite soccer players and 8 female elite team handball players aged 26 +/- 3 years at the start of the study. INTERVENTION: The subjects participated in a specific neuromuscular training program previously shown to reduce non-contact ACL injury. METHODS: Neuromuscular activity at the knee joint, joint angles at the hip and knee, and ground reaction forces were recorded during a sidecutting maneuver. Neuromuscular activity in the prelanding phase was obtained 10 and 50 ms before foot strike on a force plate and at 10 and 50 ms after foot strike on a force plate. RESULTS: Neuromuscular training markedly increased before activity and landing activity electromyography (EMG) of the semitendinosus (P < 0.05), while quadriceps EMG activity remained unchanged. CONCLUSIONS: Neuromuscular training increased EMG activity for the medial hamstring muscles, thereby decreasing the risk of dynamic valgus. This observed neuromuscular adaptation during sidecutting could potentially reduce the risk for non-contact ACL injury. [ABSTRACT FROM AUTHOR]

Background: The high incidence of knee injuries in football/handball challenges effective prevention. Identifying tangible and modifiable factors associated with a knee injury may innovate preventive actions. Engaging key stakeholders can reveal crucial insights that could improve knee injury prevention in football/handball., Objective: To investigate football/handball stakeholders' perspectives on reasons for acute and severe knee injuries to generate a conceptual model on important factors associated with knee injuries in football/handball., Methods: Mixed-method participatory Group Concept Mapping was applied to collect statements from football/handball stakeholders (players/coaches/healthcare staff/researchers) on the question, ' What may explain why some players sustain a knee injury?' . Participants rated the importance and feasibility of screening for each statement. Multidimensional scaling and hierarchical cluster analysis produced a cluster map, forming the basis for developing a final conceptual model., Results: Stakeholders (n=37) generated and sorted 100 statements. Cluster analysis followed by cluster map validation yielded seven themes: (1) the player's physical and motor skill profile, (2) preparation and training, (3) footwear and playing surface, (4) the sport's impact on the risk of injury, (5) mental and physical fatigue, (6) history of injury and 7) genetics and context. A final conceptual model illustrating factors associated with knee injuries in football/handball was developed. Forty-six statements were identified as both important and feasible to screen for., Conclusions: Stakeholders' perspectives on knee injuries in football/handball revealed a complex interplay of factors. We developed a conceptual model fostering stakeholder dialogue for enhanced prevention. Key among its themes is 'preparation and training'., Competing Interests: MH is on the scientific advisory board of the Thuasne group. All other authors (RC, TA, MKZ, KT, JB, PMH, EB, EEW) have no conflicts of interests., (Copyright © Author(s) (or their employer(s)) 2024. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Purpose: The aim of this study was to evaluate work ability, activity limitations and physical activity in adults that had gone through major bone sarcoma resection and reconstruction surgery in hip and knee., Materials and Methods: Twenty patients, of 72 enrolled, and 20 controls were included in this cross-sectional study. Work Ability Index scores (general [0-10 points], physical and mental [1-5 points]), the Patient Specific Functional Scale (0-10 points), step counts and the International Physical Activity Questionnaire (IPAQ) were assessed. Adjusted and unadjusted general linear models were applied., Results: The patients had a mean age of 43 (range, 20-71) years and were assessed 7 years (range, 2-12) after surgery (proximal femoral n  = 9, distal femoral n  = 7, proximal tibia n  = 4). Compared with controls, patients had lower general work ability (mean difference [95%CI], -1.3 points [-2.1, -0.5]) and work ability in relation to physical demands at work (-1.4 points [-2.0, -0.8]). The patients reported higher severities of activity limitation (-6.7 points [-7.9, -5.4]). There were no between-group differences in step counts or IPAQ-scores., Conclusion: Despite similar levels of physical activity, patients showed poorer work ability and severe activity limitation. Post-operative rehabilitation in patients of the working-age population should include assessments of work ability and activities important to the individual.IMPLICATIONS FOR REHABILITATIONAdults that have gone through resection and reconstruction surgery following bone sarcoma in lower extremity show clinically relevant reductions in work ability and self-selected activitiesTo tailor post-operative rehabilitation at short and long term, initial assessment and monitoring should include work ability and activities important to the individual patient.

Background: Hop performance evaluation in children after anterior cruciate ligament (ACL) reconstruction may benefit from comparison to healthy controls. Thus, the purpose was to investigate the hop performance in children one year after ACL reconstruction with a comparison to healthy controls., Methods: Hop performance data from children with ACL reconstruction one year post-surgery and healthy children were compared. Four one-legged hop test data were analyzed: 1) single hop (SH), 2) 6 m timed hop (6 m-timed), 3) triple hop (TH), and 4) cross-over hop (COH). Outcomes were the best result (longest/fastest hop) from each leg and limb asymmetry. Differences in hop performance between-limbs (operated versus non-operated) and between-groups were estimated., Results: 98 children with ACL reconstruction and 290 healthy children were included. Few statistically significant group differences were observed. Girls with ACL reconstruction outperformed healthy controls in two tests on the operated leg SH, COH) and in three tests on the non-operated leg (SH, TH, COH). However, the girls performed 4-5% worse on the operated leg when compared to the non-operated leg in all hop tests. No statistically significant between-group differences in the limb asymmetry were found., Conclusion: The hop performance in children with ACL reconstruction one year post-surgery was largely comparable to the level of healthy controls. Despite this, we cannot exclude that neuromuscular deficits exist among the children with ACL reconstruction. The inclusion of a healthy control group for evaluating hop performance evoked complex findings regarding the ACL reconstructed girls. Thus, they may represent a selected group., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Author(s). Published by Elsevier B.V. All rights reserved.)

Background: In injury prevention or rehabilitation programs, exercises that facilitate enhanced hamstring activity may be beneficial when aiming to enhance knee joint stability during movements in sports with higher risk of acute knee injury. Information about neuromuscular activation of the hamstring muscles in commonly used exercises may improve exercise selection and progression in programs for knee injury prevention or rehabilitation., Purpose: To investigate (1) how balance devices with progressing degrees of instability influence the activity of muscles controlling the knee joint in typical balance exercises with different demands on postural control, and (2) if any between-sex differences exist., Study Design: Cross-sectional study., Methods: Twenty habitually active healthy adults (11 males) participated in this cross-sectional study. Single-leg stance, single-leg squat and single-leg landing were performed on the floor and two different balance devices imposing various levels of challenge to postural control. Three-dimensional motion analysis was used to obtain hip and knee joint angles, and as primary outcomes, and peak normalized EMG activity from the hamstrings and quadriceps muscles was measured for comparison between exercises., Results: The more challenging in terms of maintaining stable balance the devices were, the higher hamstring muscle activity levels were observed. There was a clear progression across balance devices from single-leg stance to single-leg squat and further to single-leg landing displaying increasing hamstring activity levels. The change in medial hamstring activity across all devices when changing from single-leg squat to single-leg landing was significantly higher for the female participants than for the males reaching a higher level of activity., Conclusion: The muscle activity of the hamstrings and quadriceps increased when the motor task was more dynamic. Specifically, single-leg landings were effective in increasing the hamstring muscle activity over the single-leg stance to single-leg squat exercises, and muscle activity was significantly increased with the most unstable device. Increases in hamstring muscle activation was greater in female subjects than males with increasing instability of the balance devices., Trial Identifier: Not registered., Level of Evidence: 3., Competing Interests: The authors report no conflicts of interest.

Skeletal muscle function can be affected by multiple disorders in dogs of which cranial cruciate ligament rupture or disease (CCLD) is one of the most common. Despite the significance of this condition only sparse research exists regarding assessment of muscle function in dogs. This scoping review aimed to identify the non-invasive methods for canine muscle function assessments that have been reported in the literature in the past 10 years. A systematic literature search was conducted 1 st March 2022 across six databases. After screening, 139 studies were considered eligible for inclusion. Among the included studies, 18 different muscle function assessment categories were identified, and the most frequently reported disease state was CCLD. We included an attempt to elucidate the clinical applicability of the 18 reported methods, as experts were asked to subjectively assess the methods for their clinical relevance as well as their practical applicability in dogs with CCLD., Competing Interests: Adrian Harrison is a co-supervisor for KD's PhD project. Adrian Harrison established the company MyoDynamik Aps in 2011 that offers AMG equipment. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Dahl, Zebis, Vitger, Miles and Alkjær.)

Background: Ankle sprain is the most common type of sports injury, especially in team sports. Standing and dynamic landing balance, as an indicator of ankle instability, were investigated using varying experimental approaches., Methods: In the present cross-sectional study, 81 adolescent female elite handball and football players were divided into two groups based on previous ankle sprain injury (PI) or not (C). At time of test, all players were fully returned to elite-level sport. Subjects were tested during a one-legged landing (OLL) and in a one-legged static standing balance test (OLBT). In the OLL CoP trajectory displacement was calculated in 200 ms time epochs for evaluation of the initial stages of dynamic landing balance. OLBT was evaluated by calculating total displacement of the CoP trajectory., Results: CoP displacement was greater in PI than C during the first 200 milliseconds epoch after landing (P=0.001, 252 mm [44], vs. 223 mm [28]), respectively) and in the subsequent 200 ms epoch (P=0.021, 72 mm [20], vs. 61 mm [16], respectively). No significant differences between PI and C were observed in time epochs from 400 to 1000 milliseconds or in OLBT., Conclusions: Adolescent elite athletes with a history of previous ankle sprain demonstrate impaired OLL balance in the first 400 milliseconds following jump landing compared to non-injured controls. Consequently, although athletes with previous ankle sprain may return to sport, dynamic postural control may not be fully restored. Future prospective studies are needed to decide, if the OLL test could be considered a relevant criterion tool for safe return-to-sport.

Background: Differences in shoulder-disability among common shoulder-disorders in orthopaedic specialist care is unknown. Furthermore, rating of shoulder-disability using patient-reported outcomes is time-consuming, and a faster approach is needed., Objectives: First, compare shoulder-disability among common shoulder-disorders. Secondly, rate shoulder-disability according to the new and quick Copenhagen Shoulder Abduction Rating (C-SAR) and investigate criterion validity of C-SAR., Methods: Cross-sectional study including 325 consecutive patients with shoulder-disorders in orthopaedic specialist care. We assessed shoulder abduction range-of-motion and pain during testing (NRS:0-10), and shoulder-disability using Shoulder Pain and Disability Index (SPADI) subscales. Patients were sub-grouped using C-SAR, which is based on shoulder abduction range-of-motion and pain during testing: Severe (range-of-motion ≤90°), Medium (range-of-motion >90°, NRS:>5), Mild (range-of-motion >90°, NRS:≤5). Shoulder-disability was compared among diagnostic categories and C-SAR subgroups using ANCOVA-models., Results: Most patients were diagnosed with either subacromial impingement (n = 211) or full-thickness/complete rotator-cuff tear (n = 18), but adhesive capsulitis (n = 22) was the diagnostic category related to worst SPADI scores. Data for C-SAR subgrouping were available from 187/229 (82%) patients with rotator-cuff related disorders (subacromial impingement or rotator-cuff tears). C-SAR subgrouping was not feasible for patient with adhesive capsulitis or glenohumeral injury. Differences in shoulder-disability between Mild (n = 67) and Medium (n = 56) C-SAR subgroups were large for both SPADI-subscales (ES: 1.0, p < .0001). Only SPADI-function differed significantly between Severe (n = 64) and Medium C-SAR subgroups (ES: 0.4, p = .017)., Conclusion: In orthopaedic specialist care, adhesive capsulitis relates to highest level of shoulder-disability, while C-SAR is a promising test to rate shoulder-disability for most patients, namely those with rotator-cuff related disorders., (Copyright © 2022 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Non-traumatic shoulder injuries are common in team handball. However, many athletes continue to throw, despite pain in the shoulder. This study investigated upper body kinematics and muscle activation while throwing in female elite handball players with and without shoulder pain. Thirty female elite team handball players, 15 with pain (age 22.2 ± 2.9 yrs.) and 15 without pain (age 20.4 ± 2.6 yrs.) performed five standing throws in which joint kinematics and muscle activity were measured in the following muscles: pectoralis major, infraspinatus, serratus anterior, latissimus dorsi, and upper-, middle-, and lower trapezius. The main findings revealed that peak joint angles and angular velocities were not different between groups; however, group differences were observed in earlier timing of position and longer time spent in maximal shoulder extension and external shoulder rotation in the pain group compared with the no pain group. The pain group also revealed a significant lower muscle peak activity in the serratus anterior during the cocking phase compared to the no pain group. After the cocking phase and at ball release, the groups had similar activation. In conclusion, the present study showed group differences in appearance and time spent in maximal humerus extension and external rotation and a different serratus anterior muscle peak activity between elite handball players playing with and without shoulder pain, which are identified as possible mechanisms of adaptation to avoid pain., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Torabi, Juul-Kristensen, Dam, Zebis, van den Tillaar and Bencke.)

Purpose: Retraction of semitendinosus muscle has been reported after reconstruction of the anterior cruciate ligament with semitendinosus/gracilis-graft. However, very little data exist on the natural variation in side-to-side length symmetry. The purpose of this study was to investigate the side-to-side asymmetry of semitendinosus muscle length in individuals with ACL reconstruction (ACLR) using the semitendinosus/gracilis-graft compared to a group of healthy control subjects to establish the level of retraction that can confidently be ascribed the surgery., Methods: Eleven subjects aged 30 (19-39) years, with previous unilateral ACLR with the combined semitendinosus/gracilis tendon graft were recruited. Average follow-up was 6.8 years (0.3-13.0) after reconstruction. Ten healthy subjects aged 30 years (23-36) with no previous knee surgery served as controls. Bilateral magnetic resonance imaging (MRI) scans were obtained of the thigh from 60 mm below the knee joint and 700 mm proximal to this point with a slice thickness of 5 mm with 5 mm inter-slice distance. Semitendinosus length was measured on both legs between the distal and proximal musculotendinous junction of the semitendinosus. Length difference between legs was calculated for all participants. Percentage of shortening was expressed relative to the healthy leg., Results: Subjects who had undergone ACLR had on average 81 mm (25%) shortening of the semitendinosus on the reconstructed leg compared to the non-reconstructed side. The healthy subjects all had less than 10 mm difference between legs (< 3%). The side-to-side difference was significantly different between the reconstructed patients and the healthy subjects (p < 0.001)., Conclusion: This study indicates that retraction larger than 10 mm is a consequence of the tendon harvest and not natural variation. It also supports that persistent retraction of the semitendinosus muscle occurs following harvest of the semitendinosus tendon for ACL graft., Level of Evidence: Level IV., (© 2021. European Society of Sports Traumatology, Knee Surgery, Arthroscopy (ESSKA).)

Purpose: To identify modifiable biomechanical and neuromuscular anterior cruciate ligament (ACL) injury risk factors for first-time ACL injury in adolescent female elite football and team handball players., Methods: Adolescent female elite football and handball players with no previous ACL injury participated in the present study. At baseline, players were tested during side-cutting manoeuvres performed in a 3-dimensional motion analysis laboratory with concomitant electromyography (EMG) measurements. Maximal isometric lower limb muscle strength was assessed by handheld dynamometry. Players were prospectively followed for 2 years after baseline testing, and all magnetic resonance imaging (MRI) verified ACL injuries were registered. The effect of 16 risk factor candidates on the relative risk (RR) of ACL injury was estimated using Poisson regression analysis., Results: Ninety players (age 16.9 ± 1.2 years) were included in the analyses. Nine first-time ACL injuries (injury incidence 10.0% (95% confidence interval (CI) 5.4-18.6%)) were registered during the 2-year follow-up period. Four risk factor candidates were significantly associated with the risk of ACL injury: (1) hip flexion angle at initial contact (IC) [RR 0.56, 95% confidence interval (CI) 0.34-0.92], (2) internal knee rotation angle at IC [RR 1.13, 95% CI 1.08-1.19], (3) semitendinosus EMG activity 50 ms prior to IC [RR: 0.62, 95% CI 0.43-0.89], and (4) external hip rotator strength [RR: 0.77, 95% CI 0.66-0.89]., Conclusion: Four distinct ACL injury risk factors related to the side-cutting manoeuvre were identified in a population of adolescent female elite football and team handball players with no previous ACL injury. As ACL injury typically occur during side-cutting, intervention programmes to modify these risk factors pose a promising strategy for ACL injury prevention in adolescent female elite football and team handball., Level of Evidence: II., (© 2021. The Author(s).)

We evaluated the cardiometabolic effects of a 15-week combined exercise programme, implemented in sports clubs, for 50-70-year-olds with low aerobic fitness. In a randomized controlled trial, 45 participants (26 women) with low fitness were randomly assigned (2:1-ratio) to a training group (TG, n  = 30) or inactive control group (CG, n  = 15). TG had 15 weeks with one weekly 90-min supervised group-based session in a recreational sports club with combined aerobic exercise and strength training and were encouraged to perform home-based training 30 min/wk. Evaluations of relative VO 2max (mLO 2 /min/kg), blood pressure, resting heart rate (HR), echocardiography, peripheral arterial tonometry, body composition, lipid profile and HbA1c were performed at 0 and 15 wks. Average HR during supervised training was 113 ± 13 bpm (68.6 ± 7.0%HR max ), with 4.3 ± 6.6% spent >90%HR max . At 15-wk follow-up, intention-to-treat analyses revealed no between-group difference for VO 2max /kg (0.4 mLO 2 /min/kg, 95%CI -0.8-1.5, P  = 0.519; -3 mL/min, 95%CI -123-118, P  = 0.966) or other cardiovascular outcomes (all P  > 0.05). Compared to CG, total fat mass (-1.9 kg; 95%CI -3.2 to -0.5, P  = 0.005), total fat percentage (-1.3%, 95%CI -2.2 to -0.3, P  = 0.01) and total/HDL cholesterol ratio ( P  = 0.032) decreased in TG. Regular adherence to supervised training was high (81%), but 0% for home-based exercise. In conclusion, the group-based supervised training was associated with high adherence and moderate exercise intensity, whereas insufficiently supported home-based training was not feasible. Together, 15 wks of combined exercise training did not improve aerobic fitness or affected cardiovascular function in 50-70-yr-olds with low aerobic fitness, whereas some positive effects were observed in metabolic parameters. Highlights Combined exercise training implemented in a sports club elicited moderate aerobic intensity in 50-70-year-old untrained individuals.Supervised group-based training had high adherence whereas unsupported home-based training had very low adherence.15 weeks of low-frequency combined moderate intensity exercise training improved lipid profile and fat mass, but had no effect on cardiovascular fitness.

Objectives: We aimed to determine the use of injury prevention exercises and injury prevention exercise programs in Danish youth handball and investigate coach and player experiences, beliefs and attitudes of injury and their prevention., Design: A mixed-methods design consisting of cross-sectional quantitative surveys and qualitative interviews., Methods: We surveyed 481 youth (14-18 years old) handball players and their 33 coaches about their use of injury prevention exercises, and attitudes towards injury and their prevention. Additionally, we interviewed five coaches and three players about barriers and motivational factors for implementing injury prevention programs., Results: Players (71%) and almost all coaches reported performing injury prevention exercises for the shoulder, knee, and ankle. Yet few players (4%) and coaches (1%) reported performing the established full injury prevention programs systematically. Players were willing to implement programs to reduce injury risk (84% agreed) and enhance performance (88% agreed). Key factors influencing program uptake were lack of awareness of evidence-based injury prevention programs and lack of handball-specific exercises. Coaches and players identified continued education and training as vital facilitators in this setting, and all coaches agreed that injury prevention should be an essential part of coach education., Conclusions: While Danish youth handball players and coaches seemed to recognize the importance of injury prevention, the use of established programs was marginal. Experiences, beliefs, and attitudes about injury and injury prevention influenced program uptake and should be addressed through continued education and training in this context in combination with making the programs more handball specific., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Background: Patients with a bone sarcoma who undergo limb-sparing surgery and reconstruction with a tumor prosthesis in the lower extremity have been shown to have reduced self-reported physical function and quality of life (QoL). To provide patients facing these operations with better expectations of future physical function and to better evaluate and improve upon postoperative interventions, data from objectively measured physical function have been suggested., Questions/purposes: We sought to explore different aspects of physical function, using the International Classification of Functioning, Disability, and Health (ICF) as a framework, by asking: (1) What are the differences between patients 2 to 12 years after a bone resection and reconstruction surgery of the hip and knee following resection of a bone sarcoma or giant cell tumor of bone and age-matched controls without walking limitations in ICF body functions (ROM, muscle strength, pain), ICF activity and participation (walking, getting up from a chair, daily tasks), and QoL? (2) Within the patient group, do ICF body functions and ICF activity and participation outcome scores correlate with QoL?, Methods: Between 2006 and 2016, we treated 72 patients for bone sarcoma or giant cell tumor of bone resulting in bone resection and reconstruction with a tumor prosthesis of the hip or knee. At the timepoint for inclusion, 47 patients were alive. Of those, 6% (3 of 47) had undergone amputation in the lower limb and were excluded. A further 32% (14 of 44) were excluded because of being younger than 18 years of age, pregnant, having long transportation, palliative care, or declining participation, leaving 68% (30 of 44) for analysis. Thus, 30 patients and 30 controls with a mean age of 51 ± 18 years and 52 ± 17 years, respectively, were included in this cross-sectional study. Included patients had been treated with either a proximal femoral (40% [12 of 30]), distal femoral (47% [14 of 30]), or proximal tibia (13% [4 of 30]) reconstruction. The patients were assessed 2 to 12 years (mean 7 ± 3 years) after the resection-reconstruction. The controls were matched on gender and age (± 4 years) and included if they considered their walking capacity to be normal and had no pain in the lower extremity. Included outcome measures were: passive ROM of hip flexion, extension, and abduction and knee flexion and extension; isometric muscle strength of knee flexion, knee extension and hip abduction using a hand-held dynamometer; pain intensity (numeric rating scale; NRS) and distribution (pain drawing); the 6-minute walk test (6MWT); the 30-second chair-stand test (CST); the Toronto Extremity Salvage Score (TESS), and the European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire (EORTC QLQ-C30). The TESS and the EORTC QLQ-C30 were normalized to 0 to 100 points. Higher scoring represents better status for TESS and EORTC global health and physical functioning scales. Minimum clinically important difference for muscle strength is 20% to 25%, NRS 2 points, 6MWT 14 to 31 meters, CST 2 repetitions, TESS 12 to 15 points, and EORTC QLQ-C30 5 to 20 points., Results: Compared with controls, the patients had less knee extension and hip abduction strength in both the surgical and nonsurgical limbs and regardless of reconstruction site. Mean knee extension strength in patients versus controls were: surgical limb 0.9 ± 0.5 Nm/kg versus 2.1 ± 0.6 Nm/kg (mean difference -1.3 Nm/kg [95% CI -1.5 to -1.0]; p < 0.001) and nonsurgical limb 1.7 ± 0.6 Nm/kg versus 2.2 ± 0.6 Nm/kg (mean difference -0.5 Nm/kg [95% CI -0.8 to -0.2]; p = 0.003). Mean hip abduction strength in patients versus controls were: surgical limb 1.1 ± 0.4 Nm/kg versus 1.9 ± 0.5 Nm/kg (mean difference -0.7 Nm/kg [95% CI -1.0 to -0.5]; p < 0.001) and nonsurgical limb 1.5 ± 0.4 Nm/kg versus 1.9 ± 0.5 Nm/kg (-0.4 Nm/kg [95% CI -0.6 to -0.2]; p = 0.001). Mean hip flexion ROM in patients with proximal femoral reconstructions was 113° ± 18° compared with controls 130° ± 11° (mean difference -17°; p = 0.006). Mean knee flexion ROM in patients with distal femoral reconstructions was 113° ± 29° compared with patients in the control group 146° ± 9° (mean difference -34°; p = 0.002). Eighty-seven percent (26 of 30) of the patients reported pain, predominantly in the knee, anterior thigh, and gluteal area. The patients showed poorer walking and chair-stand capacity and had lower TESS scores than patients in the control group. Mean 6MWT was 499 ± 100 meters versus 607 ± 68 meters (mean difference -108 meters; p < 0.001), mean CST was 12 ± 5 repetitions versus 18 ± 5 repetitions (mean difference -7 repetitions; p < 0.001), and median (interquartile range) TESS score was 78 (21) points versus 100 (10) points (p < 0.001) in patients and controls, respectively. Higher pain scores correlated to lower physical functioning of the EORTC QLQ-C30 (Rho -0.40 to -0.54; all p values < 0.05). Less muscle strength in knee extension, knee flexion, and hip abduction correlated to lower physical functioning of the EORTC QLQ-C30 (Rho 0.40 to 0.51; all p values < 0.05)., Conclusion: This patient group demonstrated clinically important muscle weaknesses not only in resected muscles but also in the contralateral limb. Many patients reported pain, and they showed reductions in walking and chair-stand capacity comparable to elderly people. The results are relevant for information before surgery, and assessments of objective physical function are advisable in postoperative monitoring. Prospective studies evaluating the course of physical function and which include assessments of objectively measured physical function are warranted. Studies following this patient group with repetitive measures over about 5 years could provide information about the course of physical function, enable comparisons with population norms, and lead to better-designed, targeted, and timely postoperative interventions., Level of Evidence: Level III, therapeutic study., Competing Interests: All ICMJE Conflict of Interest Forms for authors and Clinical Orthopaedics and Related Research® editors and board members are on file with the publication and can be viewed on request., (Copyright © 2021 by the Association of Bone and Joint Surgeons.)

Background: A strong recommendation against subacromial decompression surgery was issued in 2019. This leaves nonoperative care as the only treatment option, but recent studies suggest that the dose of strengthening exercise is not sufficient in current nonoperative care. At this point, it is unknown if adding more strengthening to current nonoperative care is of clinical value., Purpose: To assess the effectiveness of adding a large dose of shoulder strengthening to current nonoperative care for subacromial impingement compared with usual care alone., Study Design: Randomized controlled trial; Level of evidence, 1., Methods: In this double-blinded, pragmatic randomized controlled trial, we randomly allocated 200 consecutive patients referred to orthopaedic shoulder specialist care for long-standing shoulder pain (>3 months), aged 18 to 65 years and diagnosed with subacromial impingement using validated criteria, to the intervention group (IG) or control group (CG). Outcome assessors were blinded, and participants were blinded to the study hypothesis as well as to the treatment method in the other group. The CG received usual nonoperative care; the IG underwent the same plus an add-on intervention designed to at least double the total dose of shoulder strengthening. The primary outcome was the Shoulder Pain and Disability Index (SPADI; 0-100) at 4-month follow-up, with 10 points defined as the minimal clinically important difference. Secondary outcomes included shoulder strength, range of motion, health-related quality of life, and the Patient Acceptable Symptom State (PASS)., Results: Intention-to-treat and per-protocol analyses showed no significant or clinically relevant between-group differences for any outcome. From baseline to 4-month follow-up, SPADI scores improved in both groups (intention-to-treat analysis; IG, -22.1 points; CG, -22.7 points; between-group mean difference, 0.6 points [95% CI, -5.5 to 6.6]). At 4 months after randomization, only 54% of the IG and 48% of the CG ( P = .4127) reached the PASS. No serious adverse events were reported., Conclusion: Adding a large dose of shoulder strengthening to current nonoperative care for patients with subacromial impingement did not result in superior shoulder-specific patient-reported outcomes. Moreover, approximately half of all randomized patients did not achieve the PASS after 4 months of nonoperative care, leaving many of these patients with unacceptable symptoms. This study showed that adding more exercise is not a viable solution to this problem., Registration: NCT02747251 (ClinicalTrials.gov identifier).

In rehabilitation, four single-leg hop tests are frequently used for evaluation of ACL-injured children. However, reference values on single-leg hop performance and the corresponding limb symmetry indexes (LSIs) of healthy children younger than 15 years of age are lacking. Thus, the purpose was to describe hop performance and LSIs in healthy Danish children, and to quantify the proportion of participants passing LSI values of ≥85% as well as ≥90%. Healthy children aged 9-15 years were invited to participate in the study. Hop performance (single hop, 6-m timed hop, triple hop, and cross-over hop) was assessed for each leg for each hop test and expressed as absolute, normalized (to body height), and LSI values. Descriptive statistics were applied to calculate mean ±SD for all outcomes within age and gender groups. Further, the 95% reference interval was calculated for each age and gender group. A total of 531 healthy children (52% girls) were included in the study, representing seven age groups (9-15 years). The LSI group means across all participants for the four hop tests ranged between 84 and 95%. Between 70 and 83% of the children had an LSI of ≥85%, while 50 to 65% of the children had an LSI of ≥90%. The present reference material can be used in clinical practice when evaluating hop performance in pediatric ACL patients., (© 2021 The Authors. Scandinavian Journal of Medicine & Science In Sports published by John Wiley & Sons Ltd.)

Background: Evidence-based guidelines recommend exercise-therapy as first line treatment for subacromial pain syndrome, but no previous study has mapped the content of care for subacromial pain syndrome and knowledge about adherence to clinical guidelines are lacking. We aim to describe the content and outcome of current care and investigate the relationship between content and outcome of care., Methods: We invited all patients diagnosed with subacromial pain syndrome at any Danish hospital to participate in this nationwide retrospective population-based cohort-study. Patient-reported information on content of care was collected using a validated questionnaire. Outcome of care was assessed using global impression of change (GIC) and patient acceptable symptom state (PASS). Invitations were sent 14 weeks after diagnosis., Results: In total, 3306 eligible patients participated. At follow-up, 45% had completed the recommended 12 weeks of exercise-therapy. From the total cohort, 12% underwent surgery without completing 12 weeks of exercise-therapy. For patients undergoing non-operative care, 43% reached PASS while 61% were improved since diagnosis at the hospital. Completing 12 weeks with exercise-therapy did not increase the odds of improvement (OR 1.05, 95%CI:0.88-1.24), but having conducted strengthening exercises did (OR 1.65, 95%CI:1.25-2.19)., Conclusion: More than half of patients diagnosed with subacromial pain syndrome in specialist care settings do not adhere to recommendations regarding duration of exercise-therapy, but this is not related to symptom improvement. Conversely, conducting strengthening exercises relates to higher chance of symptom improvement. This challenges current clinical guidelines, indicating that a time-based cut-point may not be relevant while specific types of exercises are., (Copyright © 2021 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Muscle strength assessment is fundamental to track the progress of performance and prescribe correct exercise intensity. In field settings, simple tests are preferred. This study develops equations to estimate maximal muscle strength in upper- and lower-extremity muscles based on submaximal elastic resistance tests. Healthy adults ( n = 26) performed a maximal test (1 RM) to validate the ability of the subsequent submaximal tests to determine maximal muscle strength, with elastic bands. Using a within-group repeated measures design, three submaximal tests of 40%, 60%, and 80% during (1) shoulder abduction, (2) shoulder external rotation, (3) hip adduction, and (4) prone knee flexion were performed. The association between number of repetitions and relative intensity was modeled with both 1st and 2nd order polynomials to determine the best predictive validity. For both upper-extremity tests, a strong linear association between repetitions and relative intensity was found (R 2 = 0.97-1.00). By contrast, for the lower-extremity tests, the associations were fitted better with a 2nd order polynomial (R 2 = 1.00). The results from the present study provide formulas for predicting maximal muscles strength based on submaximal resistance in four different muscles groups and show a muscle-group-specific association between repetitions and intensity.

Purpose: We aimed to investigate the influence of wearing a ballistic vest on physical performance in police officers., Methods: We performed a cross-over study to investigate the influence of wearing a ballistic vest on reaction and response time, lumbar muscle endurance and police vehicle entry and exit times. Reaction and response time was based on a perturbation setup where the officers' pelvises were fixed and EMG of lumbar and abdominal muscles was recorded. We used a modified Biering-Sørensen test to assess the lumbar muscle endurance and measured duration of entry and exit maneuvers in a variety of standard-issue police cars., Results: There was a significant difference of 24% in the lumbar muscle endurance test (no vest: 151 s vs. vest: 117 s), and the police officers experienced higher physical fatigue after the test when wearing a vest. Furthermore, officers took longer to both enter and exit police cars when wearing a vest (range: 0.24-0.56 s) depending on the model of the vehicle. There were no significant differences in reaction and response times between the test conditions (with/without vest)., Discussion and Conclusion: Wearing of a ballistic vest significantly influenced the speed of movement in entry and exit of police cars and lumbar muscle endurance, although it does not seem to affect reaction or response times. The ballistic vest seems to impair performance of tasks that require maximal effort, which calls for better designs of such vests.

Objective: To investigate change in shoulder rotation strength from preseason to midseason during a competitive season in youth elite handball players without shoulder problems., Design: Prospective cohort study., Methods: Players (n = 292, 45% female, 14-18 years of age) without shoulder problems from Danish youth elite handball clubs were assessed in the preseason and midseason. We measured isometric shoulder strength using handheld dynamometry in internal rotation (IR) and external rotation (ER) in supine, with the shoulder abducted 90° in neutral rotation and in 30° of IR. The primary outcome was the change in corresponding ER/IR ratio., Results: The mean ER/IR ratios increased from preseason to midseason in neutral rotation (male player difference, 0.02; 95% confidence interval [CI]: -0.01, 0.06; female player difference, 0.05; 95% CI: 0.01, 0.09) and in 30° of IR (male player difference, 0.15; 95% CI: 0.11, 0.20; female player difference, 0.12; 95% CI: 0.07, 0.17). The change in ER/IR ratio may be explained by an increase in ER strength in female players and a decrease in IR strength in male players. The amount of change in ER/IR ratio over the season was greater than individual measurement error metrics for 45% to 66% of the players., Conclusion: Shoulder rotation strength ratios changed during a competitive season in Danish youth elite handball players. J Orthop Sports Phys Ther 2020;50(7):381-387. doi:10.2519/jospt.2020.9183 .

Background: Non-contact anterior cruciate ligament (ACL) injuries are a major problem among adolescent female soccer and handball players. Therefore, the aim of this study was to examine if known biomechanical and neuromuscular ACL injury risk factors obtained from single-planar jump-landings and multi-planar side-jumps can resemble the demands of side-cutting maneuvers, a known high-risk ACL injury movement for this population., Methods: Twenty-four female soccer and handball players (mean ± SD: age: 17 ± 1 year; height: 172 ± 66 cm; mass: 67 ± 9 kg) performed a series of functional tasks including two single-planar jump-landings, two multi-planar side-jumps and a sports-specific side-cutting maneuver on their dominant leg. Frontal and sagittal plane knee and hip joint kinematics and kinetics were calculated from three-dimensional motion analysis, whereas hamstring and quadriceps muscle pre-activity levels were measured with surface electromyography., Results: The sports-specific side-cut was distinguished by more knee flexion at initial contact, greater abduction angles and external knee abduction moments, higher biceps femoris and semitendinosus muscle pre-activity levels than both the single-planar jump-landings and multi-planar side-jumps (p < .05). Whilst, poor-to-strong spearman rank correlation coefficients inconsistently were found for the biomechanical and neuromuscular ACL injury risk factors explored between the side-cut and the single-planar jump-landings (r s  = 0.01-0.78) and multi-planar side-jumps (r s  = 0.03-0.88) respectively., Conclusion: Single-planar jump-landings and multi-planar side-jumps should be used with caution to test for non-contact ACL injury risk factors in adolescent female soccer and handball players, because they do not mimic the biomechanical nor neuromuscular demands of the most frequent injury situation., Competing Interests: Declaration of competing interest We hereby declare, that there was no conflict of interest associated with our submission of the manuscript entitled “Biomechanical and neuromuscular comparison of single- and multi-planar jump tests and a side-cutting maneuver: Implications for ACL injury risk assessment” for consideration in The Knee., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Objectives: Regaining muscle strength is essential for successful outcome after anterior cruciate ligament injury, why progression of exercise intensity in anterior cruciate ligament injury rehabilitation is important. Thus, this study evaluated hamstring and quadriceps muscle activity progression during bodyweight exercises used in a validated anterior cruciate ligament injury rehabilitation program., Design: The study design involved single-occasion repeated measures in a randomized manner. Twenty healthy athletes (nine females) performed nine bodyweight exercises (three exercises per rehabilitation phase). Surface electromyography signals were recorded for hamstring (semitendinosus, biceps femoris) and quadriceps (vastus medialis, vastus lateralis) muscles and normalized to isometric peak electromyography., Results: Hamstring muscle activity did not increase from one rehabilitation phase to the next, ranging between 8% and 45% normalized electromyography for semitendinosus and 11% and 54% normalized electromyography for biceps femoris. Only one exercise (Cook hip lift) exhibited hamstring muscle activities more than 60% normalized electromyography. By contrast, quadriceps muscle activity increased, and late-phase exercises displayed high normalized electromyography (vastus lateralis >60% and vastus medialis >90% normalized electromyography)., Conclusions: The examined bodyweight exercises did not progress for hamstring muscle activity but successfully progressed for quadriceps muscles activity. This study highlights the need for consensus on exercise selection when targeting the hamstring muscles in the rehabilitation after anterior cruciate ligament injury.

Introduction: A significant step towards sport-related injury prevention is the introduction of easily accessible smartphone applications (apps). However, it is unknown whether this type of app-based instruction facilitates similar acute neuromuscular and biomechanical characteristics of the preventive exercises as achieved when instructed on-site by an expert. Thus, the aim was to evaluate acute neuromuscular characteristics observed during a single bout of selected lower extremity injury preventive exercises instructed by an on-screen app versus on-site individual instruction provided by a physiotherapist., Methods: In a cross-sectional study design, 47 female football and handball players were randomly assigned to receive app instruction (APP group) or on-site instruction provided by a physiotherapist (PHY group) while performing five lower extremity injury preventive exercises. The exercises performed comprised (1) one-legged balance on Airex, (2) vertical drop jump, (3) one-legged horizontal jump onto floor, (4) one-legged horizontal jump onto Airex, and (5) two-hand Kettlebell Swing. Primary outcome was hamstring (biceps femoris and semitendinosus) muscle activity. Secondary outcomes were quadriceps (vastus lateralis and medialis) muscle activity, as well as hip and knee joint angles. Muscle activity was monitored by surface electromyography (EMG) and normalized to the peak amplitude obtained during a maximal voluntary isometric contraction (MVC). Hip and knee joint angles were recorded by a 3D motion analysis system. A linear mixed model was used to evaluate the differences between experimental conditions for each outcome variable., Results: Medial hamstring (semitendinosus) muscle activity was significantly higher during one-legged jump onto Airex (17 percentage points (95% CI 7 to 27)) and Kettlebell Swing (19 percentage points (95% CI 2 to 36)) in the PHY group than the APP group. Likewise, the PHY group demonstrated 18 percentage points (95% CI 1 to 35) and 19 percentage points (95% CI 0 to 38), greater lateral quadriceps muscle (vastus lateralis) activity during one-legged jump onto floor and one-legged jump onto Airex, respectively, compared with that of the APP group., Conclusions: Complex exercises, i.e., Kettlebell Swing and one-legged jump onto Airex, are characterized by lower neuromuscular activity when using app-based instructions compared with on-site instruction provided by a physiotherapist. However, the effectiveness of app-based instruction versus on-site individual instruction in injury prevention interventions remains to be investigated in future longitudinally studies., Competing Interests: The authors declare that there are no conflicts of interest regarding the publication of this paper., (Copyright © 2019 M. K. Zebis et al.)

Background: The incidence of anterior cruciate ligament (ACL) injuries in children is increasing. However, no standardized core set of outcome measures exists for evaluating pediatric ACL injuries., Purpose: To perform a scoping review of the literature to identify patient-reported outcome measures (PROMs) and objective outcome measures used to evaluate pediatric patients after ACL injury and to classify these in accordance with the International Classification of Functioning, Disability, and Health (ICF) domains., Study Design: Systematic review; Level of evidence, 4., Methods: The literature was systematically searched with the PubMed, EMBASE, CINAHL, and PEDro databases. The inclusion criteria were Danish, Norwegian, Swedish, German, or English language; publication between 2010 and 2018; pediatric ACL injury (patients ≤15 years old); and outcome measures. The selected papers were screened for title, abstract, and full text in accordance with predefined inclusion and exclusion criteria., Results: A total of 68 papers (4286 patients; mean ± SD age, 12.2 ± 2.3 years) were included. Nineteen PROMs and 11 objective outcome measures were identified. The most frequently reported PROMs were the International Knee Documentation Committee (IKDC) Subjective Knee Form (51% of studies), Lysholm scoring scale (46% of studies) and Tegner activity rating scale (37% of studies). Additionally, return to sport was reported in 41% of studies. The most frequent objective measures were knee laxity (76% of studies), growth disturbances (69% of studies), range of motion (41% of studies), and muscle strength (21% of studies). With respect to the ICF domains, the IKDC covered all 3 ICF health domains, the Lysholm score covered the Body Structure and Function and the Activity Limitation domains, while the Tegner score covered the Participation Restriction domain. Objectively measured knee joint laxity, range of motion, and muscle strength covered 1 domain (Body Structure and Function)., Conclusion: Pediatric patients with ACL injury were mainly evaluated subjectively with the IKDC and objectively by knee joint laxity. No consensus exists in the evaluation of children after ACL injury. The majority of applied outcome measures are developed for adults. To cover the ICF health domains, future research needs to consider reliable and valid outcome measures relevant for pediatric patients with ACL injury., Competing Interests: The authors declared that there are no conflicts of interest in the authorship and publication of this contribution. AOSSM checks author disclosures against the Open Payments Database (OPD). AOSSM has not conducted an independent investigation on the OPD and disclaims any liability or responsibility relating thereto.

There is strong evidence that considerable health benefits can be achieved even with small amounts of physical activity. However, getting people to exercise regularly is a major challenge not least in the elderly population. This study investigated the feasibility and physiological health effects of a pragmatic 15-week exercise programme for sedentary elderly. In a single-blind randomised controlled trial, 45 sedentary 60-83-year-olds (25 women, 20 men) were randomly assigned (2:1 ratio) to a training group (TG, n=30) or a control group (CG, n=15). The training in TG consisted of a combination of exercise modalities (i.e., strength, aerobic fitness, stability, and flexibility training) performed once a week as supervised group-based training and a weekly home-based training for 15 weeks. Feasibility outcomes were exercise intensity, adherence, and adverse events. The primary outcome was change in aerobic fitness (VO 2max /kg). Adherence was high (81%) for the supervised exercise and low (0%) for the home-based exercise. No acute injuries occurred in TG, but 4 subjects (13%) reported considerable joint pain related to training. Average heart rate (HR) during the supervised training was 104±12 beats/min (69.3±8.0%HR max ), with 3.9±7.3% of training time >90%HR max . Intention-to-treat analyses revealed no between-group differences for aerobic fitness (P=0.790) or any secondary cardiovascular outcomes at 15-week follow-up (resting HR or blood pressure; P>0.05). Compared to CG, bodyweight (-2.3 kg, 95% CI -4.0 to -7.0; P=0.006), total fat mass (-2.0 kg, 95% CI -3.5 to -0.5; P=0.01), and total fat percentage (-1.6%, 95% CI -2.8 to -0.3; P=0.01) decreased in TG. The group-based supervised training had high adherence and moderate exercise intensity, whereas the home-based training was not feasible in this study population. This exercise programme performed once a week did not improve aerobic fitness. Thus, supervised training with more vigorous intensity control appears advisable. Clinical Study registration number is H-15016951.

Young, adolescent female athletes are at particular high risk of sustaining a non-contact anterior cruciate ligament (ACL) injury during sport. Through the last decades much attention has been directed toward various anatomical and biomechanical risk factors for non-contact ACL injury, and important information have been retrieved about the influence of external loading factors on ACL injury risk during given sports-specific movements. However, much less attention has been given to the aspect of neuromuscular control during such movements and only sparse knowledge exists on the specific muscle activation patterns involved during specific risk conditions. Therefore, the aim of this narrative review was (1) to describe anatomical aspects, strength aspects and biomechanical aspects relevant for the understanding of ACL non-contact injury mechanisms in young female athletes, and (2) to review the existing literature on lower limb muscle activation in relation to risk of non-contact ACL-injury and prevention of ACL injury in young female athletes. Studies investigating muscle activity patterns associated with sports-specific risk situations were identified, comprising cohort studies, intervention studies and prospective studies. Based on the retrieved studies, clear gender-specific differences in muscle activation and coordination were identified demonstrating elevated quadriceps activity and reduced hamstring activity in young female athletes compared to their male counterparts, and suggesting young female athletes to be at elevated risk of non-contact ACL injury. Only few studies ( n = 6) examined the effect of preventive exercise-based intervention protocols on lower limb muscle activation during sports-specific movements. A general trend toward enhanced hamstring activation was observed during selected injury risk situations (e.g., sidecutting and drop landings). Only a single study examined the association between muscle activation deficits and ACL injury risk, reporting that low medial hamstring activation and high vastus lateralis activation prior to landing was associated with an elevated incidence of ACL-injury. A majority of studies were performed in adult female athletes. The striking paucity of studies in adolescent female athletes emphasizes the need for increased research activities to examine of lower limb muscle activity in relation to non-contact ACL injury in this high-risk athlete population.

Background: The high injury incidence during match-play in female adolescent football is a major concern. In football, males and females play matches with the same football size. No studies have investigated the effect of football size on injury incidence in female adolescent football. Thus, the aim of the present study was to investigate the effects of introducing a lighter, smaller football on the injury pattern in female adolescent football., Methods: We conducted a pilot cluster randomized controlled trial including 26 football teams representing 346 adolescent female football players (age 15-18 years). The teams were randomized to a new lighter, smaller football (INT, N.=12 teams) or a traditional FIFA size 5 football (CON, N.=14 teams) during a full match-season. Acute time-loss injuries and football-exposure during match-play were reported weekly by text-message questions and verified subsequently by telephone interview., Results: In total, 46 acute time-loss injuries were registered (5 severe injuries), yielding an incidence rate of 15.2 injuries per 1000 hours of match-play (95% CI: 8.5-27.2) in INT and 18.6 injuries per 1000 hours of match-play (95% CI: 14.0-24.8) in CON. The estimated 22% greater injury incidence rate risk (IRR: 1.22 [95% CI: 0.64-2.35]) in the CON group was not significant. With an IRR of 1.22, a future RCT main study would need to observe 793 acute time-loss injuries during match-play, in order to have a power of 80%., Conclusions: A large-scaled RCT is required to definitively test for beneficial or harmful effects of a lighter, smaller football in adolescent female football.

Background: Subacromial impingement syndrome (SIS) is a painful, and often long lasting, shoulder condition affecting patient function and quality of life. In a recent study, we observed major strength impairments in shoulder external rotation and abduction (~30%) in a population of patients with pronounced and long-lasting SIS. However, the current rehabilitation of such strength impairments may be inadequate, with novel rehabilitation programmes including exercise therapy only improving external rotation strength by 4-13%. As these previous studies are the basis of current practice, this suggests that the strengthening component could be inadequate in the rehabilitation of these patients, and it seems likely that more emphasis should be placed on intensifying this part of the rehabilitation. The purpose of this study is to investigate the effectiveness of a programme consisting of progressive home-based resistance training using an elastic band, aimed at improving shoulder external rotation and abduction strength, added to usual care and initiated shortly after diagnosis has been established., Methods: A pragmatic randomised controlled superiority trial will be conducted, including 200 patients with pronounced and long-lasting SIS, diagnosed using predefined criteria. Participants will be randomised to receive either an add-on intervention of progressive home-based resistance training using an elastic band in addition to usual care or usual care alone in a 1:1 allocation ratio. The randomisation sequence is computer generated, with permuted blocks of random sizes. The primary outcome will be change in Shoulder Pain And Disability Index (SPADI) score from baseline to 16 weeks follow-up. Outcome assessors are blinded to group allocation. Intervention receivers will be kept blind to treatment allocation through minimal information about the content of the add-on intervention and control condition until group allocation is final. Analyses are performed by blinded data analysts., Discussion: If effective, the simple shoulder strengthening exercise programme investigated in this trial could easily be added to usual care. The usefulness of the trial is further supported by the magnitude of the problem, the information gained from the study and the pragmatism, patient centeredness and transparency of the trial., Trial Registration: The trial is pre-registered at ClinicalTrials.gov with the ID NCT02747251 on April 19, 2016.

Background: Impaired patient-reported shoulder function and pain, external-rotation strength, abduction strength, and abduction range-of-motion (ROM) is reported in patients with subacromial impingement (SIS). However, it is unknown how much strength and ROM improves in real-life practice settings with current care. Furthermore, outcomes of treatment might depend on specific rehabilitation parameters, such as the time spent on exercises (exercise-time), number of physiotherapy sessions (physio-sessions) and number of corticosteroid injections, respectively. However, this has not previously been investigated. The purpose of this study was to describe changes in shoulder strength, ROM, patient-reported function and pain, in real-life practice settings, and explore the association between changes in clinical core outcomes and specific rehabilitation parameters., Methods: Patients diagnosed with SIS at initial assessment at an outpatient hospital clinic using predefined criteria's, who had not undergone surgery after 6 months, were included in this prospective cohort study. After initial assessment (baseline), all patients underwent treatment as usual, with no interference from the investigators. The outcomes Shoulder Pain and Disability Index (SPADI:0-100), average pain (NRS:0-10), external rotation strength, abduction strength and abduction ROM, pain during each test (NRS:0-10), were collected at baseline and at six month follow-up. Amount of exercise-time, physio-sessions and steroid-injections was recorded at follow-up. Changes in outcomes were analyzed using Wilcoxon Signed-Rank test, and the corresponding effect sizes (ES) were estimated. The associations between changes in outcomes and rehabilitation parameters were explored using multiple regression analyses., Results: Sixty-three patients completed both baseline and follow-up testing. Significant improvements were seen in SPADI (19 points, ES:0.53, p  < 0.001) and all pain variables (median 1-1.5 points, ES:0.26-0.39, p  < 0.01), but not in strength and ROM (ES:0.9-0.12, p  > 0.2). A higher number of physio-sessions was significantly associated with larger improvements in external rotation strength (0.7 Newton/session, p  = 0.046), and higher exercise-time was significantly associated with decrease in average pain (-0.2 points/1,000 min, p  = 0.048)., Discussion: Patient-reported function and pain improved after six months of current care, but strength and ROM did not improve. This is interesting, as strengthening exercises is part of most current interventions. While two significant associations were identified between self-reported rehabilitation parameters and outcomes, the small gains per physio-session or 1,000 min of exercise-time reduces the clinical relevance of these relationships. Collectively, the findings from this study indicate room for improvement of the current rehabilitation of SIS, especially with regard to core clinical outcomes, such as strength and range of motion., Competing Interests: The authors declare there are no competing interests.

Background: Reduced lower extremity muscle strength as well as reduced lower extremity muscle pre-activity (defined as muscular activity just prior to initial ground contact) during high-risk movements are factors related to increased risk of non-contact ACL injury in adolescent female athletes. A strong relationship exists between muscle strength and muscle activity obtained during an isometric contraction, however, whether these two measures are related when muscle activity is obtained during a movement associated with a high risk of non-contact ACL injury is not known. Absence or presence of such a relationship may have implications for which training modalities to choose in the prevention of ACL injuries., Purpose: The purpose of this study was to examine the relationship between maximal muscle strength of the hip extensors, hip abductors and knee flexors and the pre-activity of these muscle groups recorded during a sidecutting maneuver (high-risk movement) in adolescent female soccer and handball athletes., Study Design: Cross-sectional study., Methods: Eighty-five adolescent (age 16.9 ± 1.2 years) female elite handball and soccer athletes were assessed for maximal hip extensor, hip abductor and knee flexor muscle strength; and muscle pre-activity (electromyography recordings over a 10 ms time interval prior to foot ground contact) of the gluteus maximus (Gmax), gluteus medius (Gmed), biceps femoris (BF) and semitendinosus (ST) during a standardized sidecutting maneuver., Results: The results of the correlation analyses demonstrated poor and statistically non-significant correlations. Maximal hip extensor force (N/kg bw) and Gmax pre-activity [r s = 0.012 (95% CI -0.202 - 0.224), p = 0.91], maximal hip abductor force (N/kg bw) and Gmed pre-activity [r s = 0.171 (95% CI -0.044 - 0.371), p = 0.11], maximal knee flexor force (N/kg bw) and BF pre-activity [r s = 0.049 (95% CI -0.166 - 0.259), p = 0.65], and maximal knee flexor force and ST pre-activity [r s = 0.085 (95% CI -0.131 - 0.293), p = 0.44]., Conclusion: In the present exploratory study, the results imply that no relationship exists between maximal lower extremity isometric muscle strength and lower extremity muscle pre-activity during sidecutting. This means that athletes with low muscle strength may not necessarily demonstrate high (or low) muscle pre-activity during sidecutting - a well-known risk movement for sustaining non-contact ACL injury., Levels of Evidence: Level 3.

Background: While strength training for the neck and shoulder muscles may be effective in reducing headache, the optimal combination of exercise frequency and duration is unknown. This study investigates the effect of different time-wise combinations of one weekly hour of strength training for the neck and shoulder muscles on headache frequency, intensity, and use of analgesics., Methods: A total of 573 office workers were randomly allocated at the cluster-level to five groups; 3 × 20 min a week of minimally supervised (3MS), 1 × 60 (1WS), 3 × 20 (3WS) or 9 × 7 (9WS) min a week of supervised high-intensity strength training for 20 weeks, or to a reference group without training (REF). Headache frequency, intensity, and use of analgesics in relation to headache were determined by questionnaire at baseline and follow-up., Results: The intention-to-treat analysis showed reduced headache frequency and intensity of approximately 50% in all training groups compared with REF at 20-week follow-up (P < 0.001). Use of analgesics was lower in the supervised training groups (1WS, 3WS and 9WS), but not in the group with minimal training supervision (3MS), compared with REF at follow-up., Conclusion: One hour of specific strength training - regardless of the distribution during the week - effectively reduced both headache frequency and intensity in office workers. Thus, a large time-wise flexibility exists when implementing specific strength training at the workplace. However, only supervised training led to a reduction in use of analgesics for headache., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Purpose: Prolonged hospital bed rest after severe injury or disease leads to rapid muscle atrophy and strength loss. Therefore, the main aim of this study was to evaluate the efficacy of lower extremity strengthening exercises using elastic resistance that can be performed while lying in a hospital bed., Methods: Using a cross-sectional design, 22 healthy individuals performed three consecutive repetitions of 14 different lower extremity exercises using elastic resistance, with a perceived intensity corresponding to 8 on the Borg CR-10 scale. Surface electromyography was measured on 13 lower extremity muscles and normalized to the maximal EMG (nEMG). Likewise, exercise satisfaction was evaluated by a questionnaire., Results: All participants were able to perform all exercises without discomfort and generally rated them satisfactory. High levels of muscle activity were observed for all prime movers. For example, the "femoris muscle setting" exercise showed high levels of muscle activity for rectus femoris, vastus lateralis, and vastus medialis (79, 75, and 79% nEMG, respectively), while biceps femoris and semitendinosus were highly active during the prone knee flexion exercise with (72 and 71% nEMG, respectively) and without Kinesiology Tape (73 and 77% nEMG, respectively)., Conclusion: High levels of muscle activity in the lower extremities can be achieved using elastic resistance exercises performed when lying in a hospital bed. Even though performed on healthy individuals, the present study has the potential to provide a reference table of exercises to select from when individualizing and progressing strengthening exercises during the early rehabilitation of bedridden individuals.

Knee injuries are common in adolescent female football. Self-reported previous knee injury and low Knee injury and Osteoarthritis Outcome Score (KOOS) are proposed to predict future knee injuries, but evidence regarding this in adolescent female football is scarce. The aim of this study was to investigate self-reported previous knee injury and low KOOS subscale score as risk factors for future knee injuries in adolescent female football. A sample of 326 adolescent female football players, aged 15-18, without knee injury at baseline, were included. Data on self-reported previous knee injury and KOOS questionnaires were collected at baseline. Time-loss knee injuries and football exposures were reported weekly by answers to standardized text-message questions, followed by injury telephone interviews. A priori, self-reported previous knee injury and low KOOS subscale scores (< 80 points) were chosen as independent variables in the risk factor analyses. The study showed that self-reported previous knee injury significantly increased the risk of time-loss knee injury [relative risk (RR): 3.65, 95% confidence (CI) 1.73-7.68; P < 0.001]. Risk of time-loss knee injury was also significantly increased in players with low KOOS subscale scores (< 80 points) in Activities of Daily Living (RR: 5.0), Sport/Recreational (RR: 2.2) and Quality of Life (RR: 3.0) (P < 0.05). In conclusion, self-reported previous knee injury and low scores in three KOOS subscales significantly increase the risk of future time-loss knee injury in adolescent female football., (© 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Background: Reduced ability to activate the medial hamstring muscles during a sports-specific sidecutting movement has been found to be a potential risk factor for non-contact ACL injury. However, whether a reduced ability to activate the medial hamstring muscle is a general neuromuscular phenomenon and thereby observable independently of the type of clinical screening tests used is not known. This cross sectional study investigated the rank correlation of knee joint neuromuscular activity between three different ACL injury risk screening tests., Methods: Sixty-two adolescent female elite football and handball players (16.7±1.3years) participated in the study. Using surface electromyography (EMG) assessment, the neuromuscular activity of medial hamstring muscle (semitendinosus, ST), lateral hamstring muscle (biceps femoris, BF) and quadriceps muscle (vastus lateralis, VL) were monitored during three standardized screening tests - i.e. one-legged horizontal hop (OLH), drop vertical jump (DJ) and sidecutting (SC). Neuromuscular pre-activity was measured in the time interval 10ms prior to initial contact on a force plate., Results: For neuromuscular hamstring muscle pre-activity, correlation analysis (Spearman correlation coefficient) showed low-to-moderate correlations between SC and 1) DJ (rs=0.34-0.36, P<0.05) and 2) OLH (rs=0.40-0.41, P<0.05), respectively., Conclusions: In conclusion, the present data suggest that hamstring pre-activity share some common variance during the examined tests. However, a lack of strong correlation suggests that we cannot generalize one risk factor during one test to another test., Clinical Relevance: The present data demonstrate that one-legged horizontal hop and drop vertical jump testing that are commonly used in the clinical setting does not resemble the specific neuromuscular activity patterns known to exist during sidecutting, a well known high risk movement for non-contact ACL injury., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Background: Adolescent female football and handball players are among the athletes with the highest risk of sustaining anterior cruciate ligament (ACL) injuries., Aim: This study evaluated the effects of evidence-based lower extremity injury prevention training on neuromuscular and biomechanical risk factors for non-contact ACL injury., Methods: 40 adolescent female football and handball players (15-16 years) were randomly allocated to a control group (CON, n=20) or neuromuscular training group (NMT, n=20). The NMT group performed an injury prevention programme as a warm-up before their usual training 3 times weekly for 12 weeks. The CON group completed their regular warm-up exercise programme before training. Players were tested while performing a side cutting movement at baseline and 12-week follow-up, using surface electromyography (EMG) and three-dimensional movement analysis. We calculated: (1) EMG amplitude from vastus lateralis (VL), semitendinosus (ST) and biceps femoris 10 ms prior to initial contact (IC) normalised to peak EMG amplitude recorded during maximal voluntary isometric contraction and (2) VL-ST EMG preactivity difference during the 10 ms prior to foot contact (primary outcome). We measured maximal knee joint valgus moment and knee valgus angle at IC., Results: There was a difference between groups at follow-up in VL-ST preactivity (43% between-group difference; 95% CI 32% to 55%). No between-group differences were observed for kinematic and kinetic variables., Conclusions: A 12-week injury prevention programme in addition to training and match play in adolescent females altered the pattern of agonist-antagonist muscle preactivity during side cutting. This may represent a more ACL-protective motor strategy., (Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/)

Background: Previous studies report varying rates of time-loss injuries in adolescent female soccer, ranging from 2.4 to 5.3 per 1000 athlete-exposures or 2.5 to 3.7 per 1000 hours of exposure. However, these studies collected data using traditional injury reports from coaches or medical staff, with methods that significantly underestimate injury rates compared with players' self-reports., Purpose: The primary aim was to investigate the injury incidence in adolescent female soccer using self-reports via mobile telephone text messaging. The secondary aim was to explore the association between soccer exposure, playing level, and injury risk., Study Design: Descriptive epidemiology study and cohort study; Level of evidence, 2 and 3., Methods: During a full adolescent female soccer season in Denmark (February-June 2012), a population-based sample of 498 girls aged 15 to 18 years was included in the prospective registration of injuries. All players were enrolled on a team participating in Danish Football Association series. Soccer injuries and exposure were reported weekly by answers to standardized text message questions, followed by individual injury interviews. Soccer exposure and playing levels were chosen a priori as the only independent variables of interest in the risk factor analyses. Injury rates and relative risks were estimated using Poisson regression. Generalized estimation equations were used to take into account that players were clustered within teams., Results: There were 498 players who sustained a total of 424 soccer injuries. The incidence of injuries was 15.3 (95% CI, 13.1-17.8), the incidence of time-loss injuries was 9.7 (95% CI, 8.2-11.4), and the incidence of severe injuries was 1.1 (95% CI, 0.7-1.6) per 1000 hours of soccer exposure. Higher average exposure in injury-free weeks was associated with a lower injury risk (P value for trend <.001), and players with low exposure (≤1 h/wk) were 3 to 10 times more likely to sustain a time-loss injury compared with other players (P < .01). Playing level was not associated with the risk of time-loss injuries (P = .18)., Conclusion: The injury incidence in adolescent female soccer is high, and this includes many severe injuries. Players with low soccer participation (≤1 h/wk) have a significantly higher injury risk compared with players participating more frequently., (© 2014 The Author(s).)

Therapists commonly use elastic bands in resistance exercises during rehabilitation of smaller muscles, such as in the shoulder. However, the effectiveness has not yet been investigated for larger muscle groups. This study investigates muscle activity during lower extremity exercises. Electromyographic (EMG) activity of 10 muscles was measured in 24 women and 18 men during lunges with elastic resistance, lunges with dumbbells, and unilateral leg press in machine using 10 repetition maximum loadings, and normalized to maximal voluntary isometric contraction EMG. Lunges with dumbbells and leg press showed higher activity than lunges with elastic resistance for the vasti and rectus femoris (P < 0.01), whereas lunges with elastic resistance showed higher activity of gluteus maximus, hamstrings, and erector spinae (P < 0.01). Gender, age, and pain in the knees and hip did not influence these findings. However, pain in the lower back decreased muscular activity of the gluteus maximus and vastus medialis (P < 0.01). Lunges with elastic resistance induce high levels of muscle activity in all the large muscle groups at the hip, knee, and back. Importantly, the efficiency of these exercises was equally high regardless of gender, age, and pain in the knees and hip, whereas pain in the lower back led to altered activation strategies., (© 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Purpose: Neck and shoulder complaints are common among employees in occupations characterized by intensive computer use. Treatment has varied from passive rest to active treatments and active treatments have often been divided into either training of the painful area or the surrounding musculature avoiding direct training of the painful area. Our study investigates the effect of the latter approach. The purpose of this study was in a randomised controlled trial to investigate if intensive scapular function training (SFT)-in terms of training of the lower trapezius and the serratus anterior muscle while minimizing direct training of the upper trapezius-is effective in reducing pain in adults with chronic non-specific pain in the neck/shoulder region., Methods: 47 office workers with chronic non-specific pain in the neck/shoulder region were randomized to 10 weeks 3 × 20 min SFT with training supervision or to a control group. At baseline and at follow-up the participants were tested for maximum isometric shoulder strength by a blinded tester. Further, once a week participants reported pain intensity of the neck/shoulder during the previous week., Results: In intention-to-treat analysis neck- and shoulder pain decreased 2.0 (95 % CI 0.35; 3.64) in SFT compared with control group (p < 0.05). Pressure Pain Threshold (PPT) increased 129 kPa in the lower trapezius in SFT compared with the control group (p < 0.01). Shoulder elevation strength increased 7.7 kg in SFT compared with the control group (p < 0.01) with no change in shoulder protraction strength., Conclusions: SFT reduces pain intensity and increases shoulder elevation strength in adults with chronic non-specific pain in the neck/shoulder region. The magnitude of improvement in pain intensity was clinically relevant.

Purpose: To determine the time-wise effect of specific resistance training on neck pain among industrial technicians with frequent neck pain symptoms., Methods: Secondary analysis of a parallel-group cluster randomized controlled trial of 20 weeks performed at two large industrial production units in Copenhagen, Denmark. Women with neck pain >30 mm VAS (N = 131) were included in the present analysis. The training group (N = 77) performed specific resistance training for the neck/shoulder muscles three times a week, and the control group (N = 54) received advice to stay active. Participants of both groups registered neck pain intensity (0-100 mm VAS) once a week., Results: Neck pain intensity was 55 mm (SD 23) at baseline. There was a significant group by time interaction for neck pain (F-value 2.61, P<0.001, DF = 19). Between-group differences in neck pain reached significance after 4 weeks (11 mm, 95% CI 2 to 20). The time-wise change in pain showed three phases; a rapid decrease in the training group compared with the control group during the initial 7 weeks, a slower decrease in pain during the following weeks (week 8-15), and a plateau during the last weeks (week 16-20). Adherence to training followed a two-phase pattern, i.e. weekly participation rate was between 70-86% during the initial 7 weeks, dropping towards 55-63% during the latter half of the training period., Conclusion: Four weeks of specific resistance training reduced neck pain significantly, but 15 weeks is required to achieve maximal pain reduction. The time-wise change in pain followed a three-phase pattern with a rapid effect during the initial 7 weeks followed by a slower but still positive effect, and finally a plateau from week 15 and onwards. Decreased participation rate may explain the decreased efficacy during the latter phase of the intervention.

Objective: The aim of this study was to evaluate muscle activity during hamstring rehabilitation exercises performed in training machine compared with elastic resistance., Design: Six women and 13 men aged 28-67 yrs participated in a crossover study. Electromyographic (EMG) activity was recorded in the biceps femoris and the semitendinosus during the concentric and the eccentric phase of hamstring curls performed with TheraBand elastic tubing and Technogym training machines and normalized to maximal voluntary isometric contraction-EMG (normalized EMG). Knee joint angle was measured using electronic inclinometers., Results: Training machines and elastic resistance showed similar high levels of muscle activity (biceps femoris and semitendinosus peak normalized EMG >80%). EMG during the concentric phase was higher than during the eccentric phase regardless of exercise and muscle. However, compared with machine exercise, slightly lower (P < 0.05) normalized EMG values were observed using elastic resistance at 30- to 50-degree knee joint angle for the semitendinosus and the biceps femoris during the concentric and the eccentric phase, respectively. Perceived loading (Borg CR10) was significantly higher (P < 0.001) during hamstring curl performed with elastic resistance (7.58 ± 0.08) compared with hamstring curl performed in a machine (5.92 ± 0.03)., Conclusions: Hamstring rehabilitation exercise performed with elastic resistance induces similar peak hamstring muscle activity but slightly lower EMG values at more extended knee angles and with higher perceived loading as hamstring curls using training machines.

Background: Soccer players with weak hip-adductor muscles are at increased risk of sustaining groin injuries. Therefore, a simple hip-adductor strengthening programme for prevention of groin injuries is needed., Objective: We aimed to investigate the effect of an 8-week hip-adductor strengthening programme, including one hip-adduction exercise, on eccentric and isometric hip-adduction strength, using elastic bands as external load., Methods: Thirty-four healthy, sub-elite soccer players, mean (±SD) age of 22.1 (±3.3) years, were randomised to either training or control. During the mid-season break, the training group performed 8 weeks of supervised, progressive hip-adduction strength training using elastic bands. The participants performed two training sessions per week (weeks 1-2) with 3×15 repetition maximum loading (RM), three training sessions per week (weeks 3-6) with 3×10 RM and three training sessions per week (weeks 7-8) with 3×8 RM. Eccentric hip-adduction (EHAD), isometric hip-adduction (IHAD) and isometric hip-abduction (IHAB) strength, and the IHAD/IHAB ratio were measured assessor-blinded preintervention and postintervention, using reliable hand-held dynamometry procedures., Results: In the training group, EHAD strength increased by 30% (p<0.001). In the control group, EHAD strength increased by 17% (p<0.001), but the increase was significantly larger in the training group compared with the control group (p=0.044). No other significant between-group strength-differences in IHAD, IHAB or the IHAD/IHAB ratio existed (p>0.05)., Conclusions: 8 weeks of hip-adduction strength training, using elastic bands, induce a relevant increase in eccentric hip-adduction strength in soccer players, and thus may have implications as a promising approach towards prevention of groin injuries in soccer.