Differences in Thigh Muscle Activation Between Standing and Landing Exercises for Knee Injury Prevention and Rehabilitation.

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.

Comparison of Shoulder Kinematics and Muscle Activation of Female Elite Handball Players With and Without Pain-An Explorative Cross-Sectional Study.

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.

Impaired one-legged landing balance in young female athletes with previous ankle sprain: a cross-sectional study.

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.

Improved metabolic fitness, but no cardiovascular health effects, of a low-frequency short-term combined exercise programme in 50-70-year-olds with low fitness: A randomized controlled trial.

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 VO2max (mLO2/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%HRmax), with 4.3 ± 6.6% spent >90%HRmax. At 15-wk follow-up, intention-to-treat analyses revealed no between-group difference for VO2max/kg (0.4 mLO2/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.

"Is it fun and does it enhance my performance?" - Key implementation considerations for injury prevention programs in youth handball.

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.

Influence of Wearing Ballistic Vests on Physical Performance of Danish Police Officers: A Cross-Over Study.

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.

Submaximal Elastic Resistance Band Tests to Estimate Upper and Lower Extremity Maximal Muscle Strength.

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 (R2 = 0.97-1.00). By contrast, for the lower-extremity tests, the associations were fitted better with a 2nd order polynomial (R2 = 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.

Shoulder Rotation Strength Changes From Preseason to Midseason: A Cohort Study of 292 Youth Elite Handball Players Without Shoulder Problems.

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.

Outcome Measures After ACL Injury in Pediatric Patients: A Scoping Review.

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.

Feasibility and Health Effects of a 15-Week Combined Exercise Programme for Sedentary Elderly: A Randomised Controlled Trial.

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 (VO2max/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%HRmax), with 3.9±7.3% of training time >90%HRmax. 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.

Muscle Activation During ACL Injury Risk Movements in Young Female Athletes: A Narrative Review.

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.

Effects of a lighter, smaller football on acute match injuries in adolescent female football: a pilot cluster-randomized controlled trial.

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.

Conservative treatment for patients with subacromial impingement: Changes in clinical core outcomes and their relation to specific rehabilitation parameters.

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.

MAXIMAL HIP AND KNEE MUSCLE STRENGTH ARE NOT RELATED TO NEUROMUSCULAR PRE-ACTIVITY DURING SIDECUTTING MANEUVER: A CROSS-SECTIONAL STUDY.

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 [rs = 0.012 (95% CI -0.202 - 0.224), p = 0.91], maximal hip abductor force (N/kg bw) and Gmed pre-activity [rs = 0.171 (95% CI -0.044 - 0.371), p = 0.11], maximal knee flexor force (N/kg bw) and BF pre-activity [rs = 0.049 (95% CI -0.166 - 0.259), p = 0.65], and maximal knee flexor force and ST pre-activity [rs = 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.

Electromyographic evaluation of high-intensity elastic resistance exercises for lower extremity muscles during bed rest.

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.

Neuromuscular Coordination Deficit Persists 12 Months after ACL Reconstruction But Can Be Modulated by 6 Weeks of Kettlebell Training: A Case Study in Women's Elite Soccer.

The aim of the present single-case study was to investigate the effect of 6 weeks' kettlebell training on the neuromuscular risk profile for ACL injury in a high-risk athlete returning to sport after ACL reconstruction. A female elite soccer player (age 21 years) with no previous history of ACL injury went through neuromuscular screening as measured by EMG preactivity of vastus lateralis and semitendinosus during a standardized sidecutting maneuver. Subsequently, the player experienced a noncontact ACL injury. The player was screened again following postreconstruction rehabilitation, then underwent 6-week kettlebell training, and was subsequently screened again at 6-week follow-up. Prior to and after postreconstruction rehabilitation the player demonstrated a neuromuscular profile during sidecutting known to increase the risk for noncontact ACL injury, that is, reduced EMG preactivity for semitendinosus and elevated EMG preactivity for vastus lateralis. Subsequently, the 6-week kettlebell training increased semitendinosus muscle preactivity during sidecutting by 38 percentage points to a level equivalent to a neuromuscular low-risk profile. An ACL rehabilitated female athlete with a high-risk neuromuscular profile changed to low-risk in response to 6 weeks of kettlebell training. Thus, short-term kettlebell exercise with documented high levels of medial hamstring activation was found to transfer into high medial hamstring preactivation during a sidecutting maneuver.

A comparison of hamstring muscle activity during different screening tests for non-contact ACL injury.

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.

Effects of evidence-based prevention training on neuromuscular and biomechanical risk factors for ACL injury in adolescent female athletes: a randomised controlled trial.

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.

Association between Neck/Shoulder Pain and Trapezius Muscle Tenderness in Office Workers.

Background. Neck/shoulder pain is a common musculoskeletal disorder among adults. The pain is often assumed to be related to muscular tenderness rather than serious chronic disease. Aim. To determine the association between neck/shoulder pain intensity and trapezius muscle tenderness in office workers. Methods. 653 employees from two large office workplaces in Copenhagen, Denmark, replied to a questionnaire on health and working conditions (mean: age 43 years, body mass index 24 kg·m(-2), computer use 90% of work time, 73% women). Respondents rated intensity of neck/shoulder pain during the previous three months on a scale of 0-10 and palpable tenderness of the upper trapezius muscle on a scale of "no tenderness," "some tenderness," or "severe tenderness." Odds ratios for tenderness as a function of neck/shoulder pain intensity were determined using cumulative logistic regression controlled for age, gender, and chronic disease. Results. The prevalence of "no," "some," and "severe" tenderness of the trapezius muscle was 18%, 59%, and 23% in women and 51%, 42%, and 7% in men, respectively (chi-square, P < 0.0001). Participants with "no," "some," and "severe" tenderness of the trapezius muscle, respectively, rated their neck/shoulder pain intensity to 1.5 (SD 1.6), 3.8 (SD 2.0), and 5.7 (SD 1.9) for women and 1.4 (SD 1.4), 3.1 (SD 2.2), and 5.1 (SD 1.7) for men. For every unit increase in neck/shoulder pain intensity, the OR for one unit increase in trapezius tenderness was 1.86 (95% confidence interval 1.70 to 2.04). Conclusion. In office workers, a strong association between perceived neck/shoulder pain intensity and trapezius muscle tenderness exists. The present study provides reference values of pain intensity among office workers with no, some, and severe tenderness of the trapezius muscle.