Leg asymmetry and muscle function recovery after anterior cruciate ligament reconstruction in elite athletes: a pilot study on slower recovery of the dominant leg.

The aim of this study was to examine performance in hopping tests in male athletes after anterior cruciate ligament reconstruction (ACLR) in the 4-to-6 months post-surgery period. A total of 36 athletes (24 ACLR and 12 controls) participated in this study. The ACLR group consisted of athletes who had undergone an ACLR on their dominant side (ACL DG n=16) or non-dominant side (ACL NDG n=8). Participants completed the following functional tests: a single-leg hop (SLH), single-leg triple hop (SL3H) and single-leg counter movement jump (SLCMJ), then the limb symmetry index (LSI) was calculated. There were no significant differences between the dominant and the non-dominant legs for all functional tests when comparing the ACL DG and the ACL NDG at 6 months after surgery. At 6 months after ACLR, the LSI of the two legs was within acceptable values, whether the athlete had the operation on their dominant or non-dominant leg (except the mean LSI for the ACL DG in the SLCMJ test). Furthermore, the control group showed higher performances as compared to the ACL group for all variables at 6 months after surgery, despite acceptable LSI. We concluded that an early return to "full participation to training" is not recommended in participants who have undergone an ACLR with patellar tendon grafts.

Motor Skill Interventions in Children With Developmental Coordination Disorder: A Systematic Review and Meta-Analysis.

OBJECTIVES: To determine the characteristics and effectiveness of motor skill interventions in children with developmental coordination disorder (DCD) and to identify potential moderators of training effects using meta-analysis. DATA SOURCES: A search was conducted in 6 databases (CINAHL Plus, Cochrane Library, Embase, ERIC, PsycINFO, and PubMed) for articles published between 1995 and August 2017 using search items which were grouped into 3 components (motor skill interventions, DCD, and age group of interest). STUDY SELECTION: Studies were included if they recruited children 3 to 17 years of age with DCD, reported performance of motor-related skills as outcomes, were published in peer-reviewed journals, and were written in English. Qualitative synthesis was conducted for all included studies. Quantitative synthesis (meta-analysis) was only conducted for studies using a (quasi) randomized controlled trial design. DATA EXTRACTION: Methodology, participant characteristics, intervention components, outcomes, and statistically significant training effects of each included study were extracted. DATA SYNTHESIS: Sixty-six studies met the inclusion criteria with 18 of the studies eligible for meta-analysis. Motor performance and cognitive, emotional, and other psychological factors were the most common outcomes. Other 3 outcome categories included perceptions and/or satisfaction regarding the children's improvement from significant others, physical fitness, and physical activity and participation. Immediate and moderate training effects were found for motor performance (Hedges g=.63; 95% confidence interval [CI], .31-.94; P<.001) and cognitive, emotional, and other psychological factors (Hedges g=0.65; 95% CI, 0.25-1.04; P=.001). Additionally, dose (minutes in total) and frequency of the intervention were significant moderators of training effect on motor performance. CONCLUSIONS: Motor skill interventions are effective in improving motor competence and performance on cognitive, emotional, and other psychological aspects in children with DCD in the short term. These effects are more robust in interventions using a large training dose and a practicing schedule of high frequency.

A comprehensive strength testing protocol offers no clinical value in predicting risk of hamstring injury: a prospective cohort study of 413 professional football players.

BACKGROUND: Hamstring injuries remain prevalent across a number of professional sports. In football, the incidence has even increased by 4% per year at the Champions League level over the last decade. The role of muscle strength or strength ratios and their association with risk of hamstring injury remain restricted by small sample sizes and inconclusive results. PURPOSE: The purpose of this study is to identify risk factors for hamstring injury in professional football players in an adequately powered, prospective cohort study. Using both established (isokinetic) and novel (eccentric hamstring test device) measures of muscle strength, we aimed to investigate the relationship between these strength characteristics over the entire range of motion with risk of hamstring injury. METHODS: All teams (n=18) eligible to compete in the premier football league in Qatar underwent a comprehensive strength assessment during their annual periodic health evaluation at Aspetar Orthopaedic and Sports Medicine Hospital in Doha, Qatar. Variables included isokinetic strength, Nordic hamstring exercise strength and dynamic hamstring: quadriceps ratios. RESULTS: Of the 413 players included (68.2% of all league players), 66 suffered a hamstring injury over the two seasons. Only isokinetic quadriceps concentric at 300°/s (adjusted for bodyweight) was associated with risk of hamstring injury when considered categorically. Age, body mass and playing position were also associated with risk of hamstring injury. None of the other 23 strength variables examined were found to be associated with hamstring injury. CONCLUSION: The clinical value of isolated strength testing is limited, and its use in musculoskeletal screening to predict future hamstring injury is unfounded.

Multi-segment trunk models used to investigate the crunch factor in golf and their relationship with selected swing and launch parameters.

The use of multi-segment trunk models to investigate the crunch factor in golf may be warranted. The first aim of the study was to investigate the relationship between the trunk and lower trunk for crunch factor-related variables (trunk lateral bending and trunk axial rotation velocity). The second aim was to determine the level of association between crunch factor-related variables with swing (clubhead velocity) and launch (launch angle). Thirty-five high-level amateur male golfers (Mean ± SD: age = 23.8 ± 2.1 years, registered golfing handicap = 5 ± 1.9) without low back pain had kinematic data collected from their golf swing using a 10-camera motion analysis system operating at 500 Hz. Clubhead velocity and launch angle were collected using a validated real-time launch monitor. A positive relationship was found between the trunk and lower trunk for axial rotation velocity (r(35) = .47, P < .01). Cross-correlation analysis revealed a strong coupling relationship for the crunch factor (R(2) = 0.98) between the trunk and lower trunk. Using generalised linear model analysis, it was evident that faster clubhead velocities and lower launch angles of the golf ball were related to reduced lateral bending of the lower trunk.

Effects of Fundamental Movement Skills Training on Children With Developmental Coordination Disorder.

The purpose of this study was to examine the effects of fundamental movement skills (FMS) training on FMS proficiency, self-perceived physical competence (SPC), physical activity (PA), and sleep disturbance in children with developmental coordination disorder (DCD) compared with children with typical development (TD). A total of 84 children were allocated into either experimental group (DCD[exp], TD[exp]) who received 6 weeks of FMS training or control groups (DCD[con], TD[con]). FMS were assessed using the Test of Gross Motor Development-2, whereas PA was monitored using accelerometers. SPC and sleep disturbance were evaluated using questionnaires. Results showed that the DCD[exp] group had significantly higher scores in FMS and SPC compared with the DCD[con] group at posttest. The DCD[exp] group scored lower in sleep disturbance at follow-up when compared with posttest. It is suggested that short-term FMS training is effective in improving FMS and SPC and reducing sleep disturbances for children with DCD.

Psychometric properties of the Chinese (Cantonese) versions of the KIDSCREEN health-related quality of life questionnaire.

PURPOSE: The KIDSCREEN questionnaire assesses health-related quality of life in children and adolescents. In this study, the questionnaire was translated into Chinese (Cantonese) and administered to two independent groups of Hong Kong Chinese students. Various aspects of reliability and validity of the KIDSCREEN-52 and KIDSCREEN-27 questionnaires were examined. METHODS: The translated KIDSCREEN-52 questionnaire (and thus the KIDSCREEN-27 as a subset of the long form) was administered to cohorts of 1379 and 555 students. Confirmatory factor analysis and partial credit Rasch analyses were used to examine the underlying structure of the instrument. Test-retest reliability, convergent, and divergent validity were also examined. RESULTS: The 10-factor structure of the Chinese KIDSCREEN-52 was supported. However, the original five-factor model of the KIDSCREEN-27 was not supported as seven distinct factors were found. Internal consistency and test-retest reliability were acceptable. Evidence supporting convergent and divergent validity was found. CONCLUSIONS: Results from the two studies supported the use of the translated Chinese version of KIDSCREEN questionnaire children and adolescents' health-related quality of life. Further research is required to examine possible cultural or language differences between the original version and the translated Chinese version of the questionnaire.

Cognitive functional approach to manage low back pain in male adolescent rowers: a randomised controlled trial.

BACKGROUND: Low back pain (LBP) is prevalent among adolescent rowers. This study evaluated the efficacy of a cognitive functional approach to reduce LBP in this population. METHODS: Thirty-six adolescent male rowers reporting LBP participated. Nineteen were randomly allocated to the intervention group to receive a cognitive functional approach targeting cognitions, movement patterns, conditioning and lifestyle factors relevant to each rower for 8 weeks. The active control group (n=17) received usual care from their coaches (rowing skills and conditioning exercises). The primary outcome of the study was pain intensity as measured by the Numeric Pain Rating Scale during a 15 min ergometer trial preintervention and postintervention. Disability (Patient Specific Functional Scale and Roland Morris Disability Questionnaire) was measured preintervention/postintervention and at 12 weeks follow-up. Isometric muscle endurance of the back extensors and lower limb muscles, usual sitting posture and regional lumbar kinematic data during a 15 min ergometer row were measured preintervention/postintervention. RESULTS: Compared with the control group, the intervention group reported significantly less pain during ergometer rowing (Numeric Pain Rating Scale -2.4, p=0.008) and reduced disability (Patient Specific Functional Scale (4.1, p=0.01); Roland Morris Disability Questionnaire (-1.7, p=0.003)) following the intervention, and at 12 weeks follow-up. They also demonstrated greater lower limb muscle endurance (20.9 s, p=0.03) and postured their lower lumbar spine in greater extension during static sitting (-9.6°, p=0.007). No significant differences were reported in back muscle endurance and regional lumbar kinematics during ergometer rowing. CONCLUSION: Cognitive functional approach was more effective than usual care in reducing pain and disability in adolescent male rowers. CLINICAL TRIAL REGISTRY NUMBER: Australian and New Zealand Clinical Trial Registry Number 12609000565246.

Carry-Over of Force Production Symmetry in Athletes of Differing Strength Levels.

This study sought to determine the level of association between bilateral force production symmetry assessment methods (standing weight distribution [WtD], unloaded and lightly loaded jumps, and isometric strength) and to determine whether the amount of symmetry carry-over between these tasks differs for strong and weak athletes. Subjects for this study included male (n = 31) and female (n = 32) athletes from National Collegiate Athletic Association Division I sports. Athletes performed WtD, unloaded and lightly loaded (20 kg) static and countermovement jumps, and isometric midthigh pull (IMTP) assessments on 2 adjacent force plates. Ground reaction force data were used to calculate symmetry variables and performance-related variables. Using Pearson zero order correlations, evaluations of the amount of symmetry carry-over were made. Weight distribution correlated strongly with jump peak force (PF) (r = 0.628-0.664). Strong relationships were also observed between loading conditions for jump variables (r = 0.568-0.957) as were the relationships between jump types for PF, peak power, and net impulse (r = 0.506-0.834). Based on the pooled sample, there was a lack of association between IMTP and WtD for jump symmetry variables. However, when examining strong and weak groups, rate of force development showed moderate to strong symmetry carry-over in the strongest athletes (r = 0.416-0.589). Stronger athletes appear to display similar explosive strength symmetry characteristics in dynamic and isometric assessments, unlike weaker athletes. Strength seems to influence the amount of force production symmetry carry-over between bilateral assessments. There may be optimal loads and variables for symmetry assessment, but these may differ based on population characteristics.

Spinal Kinematics of Adolescent Male Rowers with Back Pain in Comparison with Matched Controls During Ergometer Rowing.

There is a high prevalence of low back pain (LBP) in adolescent male rowers. In this study, regional lumbar spinal kinematics and self-reported LBP intensity were compared between 10 adolescent rowers with moderate levels of LBP relating to rowing with 10 reporting no history of LBP during a 15-minute ergometer trial using an electromagnetic tracking system. Adolescent male rowers with LBP reported increasing pain intensity during ergometer rowing. No significant differences were detected in mean upper or lower lumbar angles between rowers with and without LBP. However, compared with rowers without pain, rowers with pain: (1) had relatively less excursion of the upper lumbar spine into extension over the drive phase, (2) had relatively less excursion of the lower lumbar spine into extension over time, (3) had greater variability in upper and lower lumbar angles over the 15-minute ergometer trial, (4) positioned their upper lumbar spine closer to end range flexion for a greater proportion of the drive phase, and (5) showed increased time in sustained flexion loading in the upper lumbar spine. Differences in regional lumbar kinematics exist between adolescent male rowers with and without LBP, which may have injury implication and intervention strategies.

Low BACK PAIN BELIEFS AND THEIR RELATIONSHIPS WITH Low BACK PAIN-RELATED DISABILITY IN NURSES WORKING IN MAINLAND CHINA AND IN AUSTRALIA.

Beliefs held about low back pain (LBP) can influence treatment outcomes and the development of LBP-related disability. Beliefs are shaped by cultural norms but few cross-cultural studies have been done. This cross-sectional study investigated the back pain beliefs and their associations with disability in 109 Chinese nurses and 165 Australian Caucasian nurses. Chinese nurses held more pessimistic views about the consequences of LBP than the Australian and those with LBP held higher level of fear avoidance beliefs and had higher disability than the Australian nurses with LBP. In both groups, more negativeback pain beliefs were significantly associated with higher disability.

Low back pain beliefs are associated to age, location of work, education and pain-related disability in Chinese healthcare professionals working in China: a cross sectional survey.

BACKGROUND: Low back pain (LBP) is the leading cause of disability worldwide. Evidence pointing towards a more efficacious model of care using a biopsychosocial approach for LBP management highlights the need to understand the pain-related beliefs of patients and those who treat them. The beliefs held by healthcare professionals (HCPs) are known to influence the treatment advice given to patients and consequently management outcomes. Back pain beliefs are known to be influenced by factors such as culture, education, health literacy, place of work, personal experience of LBP and the sequelae of LBP such as disability. There is currently a knowledge gap among these relationships in non-western countries. The aim of this study was to examine the associations between LBP-related beliefs among Chinese HCPs and characteristics of these HCPs. METHODS: A convenience sample of 432 HCPs working in various health settings in Shanghai, China, completed a series of questionnaires assessing their demographic characteristics, LBP status, pain-related disability and their beliefs about their own LBP experience, using the Back beliefs Questionnaire (BBQ) and the Fear Avoidance Beliefs Questionnaire (FABQ). RESULTS: Younger Chinese HCPs (20-29 years) held more negative beliefs and attitudes related to LBP compared to older HCPs (>40years; BBQ mean difference [95% CI]: 2.4 [0.9 - 3.9], p = 0.001). HCPs working outside tertiary hospitals had poorer beliefs concerning the inevitable consequences of LBP (BBQ mean difference [95% CI]: -2.4 [-3.8 - -1.0], p = 0.001). HCPs who experienced LBP had higher level of fear avoidance beliefs when experiencing high LBP-related disability (FABQ-physical mean difference [95% CI]: 2.8 [1.5 - 4.1], p < 0.001; FABQ-work mean difference [95% CI]: 6.2 [4.0 - 8.4], p < 0.001)) and had lower level of fear avoidance beliefs if they had completed postgraduate study (FABQ-physical mean difference [95% CI]: 2.9 [-5.8 - 0.0], p = 0.049). CONCLUSION: This study suggests that LBP-related beliefs and attitudes among Chinese HCPs are influenced by age, location of work, level of LBP-related disability and education level. Understanding back pain beliefs of Chinese HCPs forms an important foundation for future studies into the condition and its management in China.

Two tests of approach-iron golf skill and their ability to predict tournament performance.

The aim of this study was to investigate the convergent and predictive validity of two skill tests that examine the ability of golfers to hit accurate approach-iron shots. Twenty-four high-level golfers (handicap = 2.6 ± 1.7) performed the Nine-Ball Skills Test (assesses the ability to shape/control ball trajectory with high accuracy) and the Approach-Iron Skill Test (assesses the ability to hit straight shots from varying distances with high accuracy). Participants then completed at least eight rounds of tournament golf over the following 90 days and reported an indicator of approach-iron accuracy (per cent error index). A moderate correlation (r = 0.50, P < 0.05) was noted between scores for both tests. Generalised estimating equations, using two covariates (lie of the ball and distance to hole), were used to determine model fit and the amount of variance explained for tournament per cent error index. Results showed that the Approach-Iron Skill Test was the slightly stronger predictor of on-course per cent error index. With both test scores considered together, a minimal amount of additional variance was explained. These findings suggest that either of the tests used individually or combined may be used to predict tournament approach iron performance in high-level golfers.

A new method to identify the location of the kick point during the golf swing.

No method currently exists to determine the location of the kick point during the golf swing. This study consisted of two phases. In the first phase, the static kick point of 10 drivers (having identical grip and head but fitted with shafts of differing mass and stiffness) was determined by two methods: (1) a visual method used by professional club fitters and (2) an algorithm using 3D locations of markers positioned on the golf club. Using level of agreement statistics, we showed the latter technique was a valid method to determine the location of the static kick point. In phase two, the validated method was used to determine the dynamic kick point during the golf swing. Twelve elite male golfers had three shots analyzed for two drivers fitted with stiff shafts of differing mass (56 g and 78 g). Excellent between-trial reliability was found for dynamic kick point location. Differences were found for dynamic kick point location when compared with static kick point location, as well as between-shaft and within-shaft. These findings have implications for future investigations examining the bending behavior of golf clubs, as well as being useful to examine relationships between properties of the shaft and launch parameters.

Gender differences in trunk and pelvic kinematics during prolonged ergometer rowing in adolescents.

The trunk and pelvis kinematics of 20 healthy male and female adolescent rowers were recorded during an ergometer trial using an electromagnetic tracking system (Fastrak). The kinematics of each drive phase were collected during the 1st and 20th minute, respectively. The mean and range of the kinematics, stroke rate and stroke length were compared between genders and over time. Male rowers postured their pelvis with more posterior tilt and their thoracic spine in more flexion than female rowers (P < .05). Both genders postured their pelvis in more posterior pelvic rotation and upper trunk in more flexion over time. Male rowers were found to have a significantly shorter drive phase than female rowers (P = .001). Differences in trunk and pelvic kinematics between adolescent male and female rowers suggest potentially various mechanisms for biomechanical stress. Assessment and training of rowers should take gender differences into consideration.

Three-dimensional trunk kinematics in golf: between-club differences and relationships to clubhead speed.

The aims of this study were (i) to determine whether significant three-dimensional (3D) trunk kinematic differences existed between a driver and a five-iron during a golf swing; and (ii) to determine the anthropometric, physiological, and trunk kinematic variables associated with clubhead speed. Trunk range of motion and golf swing kinematic data were collected from 15 low-handicap male golfers (handicap = 2.5 +/- 1.9). Data were collected using a 10-camera motion capture system operating at 250 Hz. Data on clubhead speed and ball velocity were collected using a real-time launch monitor. Paired t-tests revealed nine significant (p < or = 0.0019) between-club differences for golf swing kinematics, namely trunk and lower trunk flexion/extension and lower trunk axial rotation. Multiple regression analyses explained 33.7-66.7% of the variance in clubhead speed for the driver and five-iron, respectively, with both trunk and lower trunk variables showing associations with clubhead speed. Future studies should consider the role of the upper limbs and modifiable features of the golf club in developing clubhead speed for the driver in particular.

Can a Specific Neck Strengthening Program Decrease Cervical Spine Injuries in a Men's Professional Rugby Union Team? A Retrospective Analysis.

Cervical spine injuries in Rugby Union are a concerning issue at all levels of the game. The primary aim of this retrospective analysis conducted in a professional Rugby Union squad was to determine whether a 26-week isometric neck strengthening intervention program (13-week strengthening phase and 13-week maintenance phase) was effective in reducing the number and severity of cervical spine injuries. The secondary aim was to determine whether at week five, where the program had been the similar for all players, there was increased isometric neck strength. All 27 players who were common to both the 2007-2008 and 2008-2009 seasons were included in this analysis and data was extracted from a Sports Medicine/Sports Science database which included the squad's injury records. Primary outcome variables included; the number of cervical spine injuries and the severity of these injuries as determined by the total number of days lost from training and competition. Secondary outcome variables included isometric neck strength in flexion, extension and left and right lateral flexion. Using non-parametric statistical methods, no significant differences were evident for the total number of cervical spine injuries (n = 8 in 2007-2008, n = 6 in 2008-2009) or time loss due to these injuries (100 days in 2007-2008, 40 days in 2008-2009). However, a significant (p = 0.03) reduction in the number of match injuries was evident from 2007-2008 (n = 11) to 2008-09 (n = 2). Non-significant increases in isometric neck strength were found in all directions examined. A significant reduction in the number of match injuries was evident in this study. However, no other significant changes to primary outcome variables were achieved. Further, no significant increases in isometric neck strength were found in this well-trained group of professional athletes. Key PointsWhile many authors have proposed that neck strengthening could be an effective strategy in preventing cervical spine injuries in Rugby Union, there is currently little information in the literature pertaining to how such a study might be conducted.A significant decrease in the number of injuries recorded in matches can be achieved using a specific neck strengthening program at the elite level.In an elite rugby union team as investigated in this study a significant increase in neck strength is difficult to achieve in a short period of time such as five weeks.

Chronic low back pain is associated with reduced vertebral bone mineral measures in community-dwelling adults.

BACKGROUND: Chronic low back pain (CLBP) experienced in middle-age may have important implications for vertebral bone health, although this issue has not been investigated as a primary aim previously. This study investigated the associations between CLBP and dual energy X-ray absorptiometry (DXA)-derived vertebral bone mineral measures acquired from postero-anterior and lateral-projections, among community-dwelling, middle-aged adults. METHODS: Twenty-nine adults with CLBP (11 male, 18 female) and 42 adults with no history of LBP in the preceding year (17 male, 25 female) were evaluated. Self-reported demographic and clinical data were collected via questionnaires. Areal bone mineral density (aBMD) was measured in the lumbar spine by DXA. Apparent volumetric (ap.v) BMD in the lumbar spine was also calculated. Multiple linear regression models were used to examine associations between study group (CLBP and control) and vertebral DXA variables by gender, adjusting for height, mass and age. RESULTS: There was no difference between groups by gender in anthropometrics or clinical characteristics. In the CLBP group, the mean (SD) duration of CLBP was 13.3 (10.4) years in males and 11.6 (9.9) years in females, with Oswestry Disability Index scores of 16.2 (8.7)% and 15.4 (9.1)%, respectively. Males with CLBP had significantly lower adjusted lateral-projection aBMD and lateral-projection ap.vBMD than controls at L3 with mean differences (standard error) of 0.09 (0.04) g/cm2 (p = 0.03) and 0.02 (0.01) g/cm3 (p = 0.04). These multivariate models accounted for 55% and 53% of the variance in lateral-projection L3 aBMD and lateral-projection L3 ap.vBMD. CONCLUSIONS: CLBP in males is associated with some lumbar vertebral BMD measures, raising important questions about the mechanism and potential clinical impact of this association.

Development of the Nine-Ball Skills Test to discriminate elite and high-level amateur golfers.

Currently, there is a lack of appropriate skill assessments available for use in golf. The aim of this study was to examine the discriminative validity and the test-retest reliability of the newly developed "Nine-Ball Skills Test". Participants of two ability levels (elite, n = 14; high-level amateur, n = 16) each hit nine golf shots of differing combinations of trajectory (straight, fade, draw) and height (normal, high, low) at an individually determined target area. Each shot was scored on its percent error index from the target and whether it achieved the maximum height as required. Participants completed the test twice using a 5-iron club. The elite group scored significantly higher (P < 0.05) than the amateur group for both the first and second rounds of the test as well as the combined scores. The between-round test-retest reliability was deemed to be not acceptable, thus we propose that the test's protocol should include use of the two rounds as standard. Due to the importance of ball striking and flight control to performance in golf, the Nine-Ball Skills Test is appropriate for providing a measure of this skill component in elite and high-level amateur golfers.

Levels of muscle activation in strength and conditioning exercises and dynamometer hiking in junior sailors.

Although strength and conditioning exercises have been prescribed to enhance performance and prevent injury in sailors, little is known about these exercises in comparison to the demands placed on the sailor's musculature while hiking maximally. Because of the difficulty in collecting hiking-related data on water, a 3-minute maximal hiking test (HM180) has been previously developed for use in the laboratory setting. There were 2 aims of this study. The first aim was to determine whether discriminative validity could be shown for the HM180 test in a group of junior sailors of differing ability level and gender. The second aim was to determine whether differences in muscle activation existed between selected strength and conditioning exercises and the HM180 test. Twenty-nine adolescent boy and girl sailors aged between 14 and 16 years from the Singaporean National Byte Class training squad (n = 12) and the Singapore High Participation Group (n = 17) were recruited for this study. The average levels of normalized muscle activation in selected lower limb and trunk muscles in 4 selected strength and conditioning exercises (leg extension, back squat, and back extension exercises, a 30-second hiking hold) and a maximal 3-minute hiking test (the HM180 test) were quantified. Discriminative validity of the HM180 test was shown, and it was confirmed that the strength and conditioning exercises provide an overload stimulus for the HM180 test. Further, similar levels of muscle activation were found for the vastus lateralis in the leg extension and back squat exercises, and the superficial lumbar multifidus in the back extension and back squat exercises. This study has the potential to inform the design of strength and conditioning programs for junior sailors.

Kinetic analysis of push-up exercises: a systematic review with practical recommendations.

Push-ups represent one of the simplest and most popular strengthening exercise. The aim of this study was to systematically review and critically appraise the literature on the kinetics-related characteristics of different types of push-ups, with the objective of optimising training prescription and exercise-related load. A systematic search was conducted in the electronic databases PubMed, Google Scholar and Science Direct up to April 2018. Studies that reported kinetic data (e.g. initial and peak-force supported by the upper-limbs, impact-force, peak-flexion-moment of the elbow-joint, rate of propulsive- and impact-, and vertebral-joint compressive-forces) related to push-ups and included trained, recreational and untrained participants, were considered. The risk of bias in the included studies was assessed using the Critical Appraisal Skills Programme scale. From 5290 articles retrieved in the initial search, only 26 studies were included in this review. Kinetic data for 46 push-up variants were assessed. A limitation of the current review is that the relationship between our findings and actual clinical or practical consequences is not statistically proven but can only be inferred from our critical descriptive approach. Overall, this review provides detailed data on specific characteristics and intensities of push-up variations, in order to optimise exercise prescription for training and rehabilitation purposes.