Coronal plane hip muscle activation in football code athletes with chronic adductor groin strain injury during standing hip flexion

Core stability is associated with dynamic postural balance in soccer players experiencing groin pain without time-loss

Objectives

The study sought to evaluate possible relationships between dynamic postural balance and pain, core stability, and hip range of motion in soccer players who were experiencing groin pain (GP). Furthermore, the study aimed to compare these measurements in symptomatic and asymptomatic players.

Methods

The study included 42 male soccer players experiencing GP and an equal number of asymptomatic players. Dynamic postural balance, pain, hip range of motion and trunk endurance were measured.

Results

The GP group revealed reduced dynamic balance performance (p < 0.01-0.001) in injured and non-injured limbs compared to control group. Further, players experiencing GP demonstrated lower hip range of motion in internal (p < 0.05) and total rotations (p < 0.01) in the injured limb, and lower trunk endurance (p < 0.001) compared to their asymptomatic peers. In general, core stability was associated (r = 0.13-0.61, p < 0.05-0.001) with the poor dynamic balance performance in the GP group while standing on injured and non-injured limbs. No significant correlations between dynamic postural balance, pain and hip range of motion were observed.

Conclusion

Poor core endurance was found to be associated with dynamic balance disorders in soccer players experiencing GP. This information can aid in the development of targeted strategies to enhance dynamic postural balance in these players.

Effects of differences in femoral anteversion and hip flexion angle on hip abductor muscles activity during clam exercise in females

This study aimed to determine differences in the hip abductor muscle activity during clam exercise at different hip flexion and femoral anteversion angles. Thirty healthy females were divided into two groups based on the femoral anteversion angle: the excessive femoral anteversion group and the normal group. Clam exercise was performed at three different hip flexion angles (60°, 45°, and 30°). Tensor fascia latae, gluteus medius, and superior portion of gluteus maximus activities were measured during the exercise, and the results were normalized to the activity during maximum voluntary isometric contraction to calculate the gluteal-to-tensor fascia latae muscle activation index. The superior portion of gluteus maximus activities at a hip flexion of 60° and 45° were greater than that at 30°. The excessive femoral anteversion group had a lower gluteal-to-tensor fascia latae muscle activation index than the normal group; the gluteal-to-tensor fascia latae muscle activation index for hip flexion at 60° was higher than that at 45°, and the gluteal-to-tensor fascia latae muscle activation index for hip flexion at 60° and 45° were higher than that at 30°. Therefore, the femoral anteversion angle and hip joint position were related to the activity of the hip abductor muscles during clam exercise. These findings may provide a rationale for instructing exercises to maximize the activity of the hip abductor muscles in individuals with an excessive femoral anteversion angle.

Movement Variability and Loading Characteristics in Athletes With Athletic Groin Pain: Changes After Successful Return to Play and Compared With Uninjured Athletes

Background:

Athletic groin pain (AGP) can lead to altered movement patterns during rapid deceleration and acceleration. However, the effect of AGP on movement variability and loading patterns during such actions remains less clear.

Purpose:

To investigate, using a continuous lateral hurdle hop task, how movement variability and magnitude measures of 3-dimensional (3D) kinematic, kinetic, and vertical ground-reaction force (vGRF) variables are (1) affected by AGP (AGP vs uninjured controls [CON]) and (2) changed after successful rehabilitation (AGP prerehabilitation vs AGP postrehabilitation vs CON).

Study Design:

Controlled laboratory study.

Methods:

A total of 36 athletes diagnosed with AGP and 36 uninjured CON athletes matched on age (18-35 years), level (subelite), and type of sports played (multidirectional field sport) performed a continuous lateral hurdle hop test that involved 10 side-to-side hops over a 15-cm hurdle. The 3D joint kinematic, kinetic, and vGRF variables (total, eccentric, and concentric; ground contact time, peak force, and impulse; and eccentric rate of force development) were examined. The AGP and CON groups were tested at baseline, and the AGP group was retested after participants successfully completed a standardized, exercise-based rehabilitation program targeting intersegmental control.

Results:

There were no differences in baseline characteristics between the AGP (mean ± SD: age, 27.5 ± 4.8 years; height, 179.8 ± 6.3 cm; mass, 80.3 ± 7.1 kg) and CON (mean ± SD: age, 24.1 ± 4.5 years; height, 181.0 ± 5.8 cm; mass, 80.4 ± 8.2 kg) groups. At baseline, athletes with AGP demonstrated altered loading patterns in the vGRF (longer ground contact times, reduced peak force, and reduced rate of force development) compared with CON athletes, while no significant difference in any movement variability variables was evident. After rehabilitation, the athletes with AGP demonstrated significant changes in transverse and coronal plane hip and trunk kinematics, with no significant differences in vGRF variables compared with the CON group.

Conclusion:

The differences in baseline vGRF measures between the AGP and CON groups were no longer evident after athletes with AGP underwent rehabilitation. No differences in movement variability were evident between the AGP and CON groups, either before or after rehabilitation.

Clinical Relevance:

Rehabilitation programs should consider targeting intersegmental hip and trunk movement patterns to positively influence loading patterns in athletes with AGP.

Intra and inter-tester reliability of a novel device to assess gluteal muscle strength in professional football players

The aim of this study is to investigate inter-tester and intra-tester reliability of a novel clam test (CLAMT) for the measurement of gluteal muscle strength and to detect possible differences between CLAMT values in football players with and without a history of groin injuries. Twenty male football players participated in the test-retest and sixty-two male professional football players participated in the case-control study. Hip abductor maximal muscle strength was evaluated either using CLAMT or in a supine position with the hip in a neutral pose. For CLAMT, intraclass correlation coefficient (ICC) for inter-tester-intra-day reliability was 0.80 (95% CI: 0.60-0.90), with a standard error of measurement of 34.2 N. The intra-tester-intra-day ICC was 0.92 (95% CI: 0.87-0.95), with a standard error of measurement of 23.6 N. The inter-week ICC was 0.96 (95% CI: 0.92-0.98), with a standard error of measurement of 18.9 N. CLAMT showed lower (but not significant) strength values in football players with a history of groin injuries to non-injured players. CLAMT showed good to excellent levels of reliability, intraday and inter-week, with low standard errors of measurement while it was effective (possible) to identify residual weakness in players with previous groin injuries.

A SYSTEMATIC REVIEW AND META-ANALYSIS OF COMMON THERAPEUTIC EXERCISES THAT GENERATE HIGHEST MUSCLE ACTIVITY IN THE GLUTEUS MEDIUS AND GLUTEUS MINIMUS SEGMENTS

Background

The gluteus medius (GMed) and gluteus minimus (GMin) muscle segments demonstrate different responses to pathology and ageing, hence it is important in rehabilitation that prescribed therapeutic exercises can effectively target the individual segments with adequate exercise intensity for strengthening.

Purpose

The purpose of this systematic review was to evaluate whether common therapeutic exercises generate at least high ( > 40% maximum voluntary isometric contraction (MVIC)) electromyographic (EMG) activity in the GMed (anterior, middle and posterior) and GMin (anterior and posterior) segments.

Methods

Seven databases (MEDLINE, EMBASE, CINAHL, AusSPORT, PEDro, SPORTdiscus and Cochrane Library) were searched from inception to May 2018 for terms relating to gluteal muscle, exercise, and EMG. The search yielded 6918 records with 56 suitable for inclusion. Quality assessment, data extraction and data analysis were then undertaken with exercise data pooled into a meta-analysis where two or more studies were available for an exercise and muscle segment.

Results

For the GMed, different variations of the hip hitch/ pelvic drop exercise generated at least high activity in all segments. The dip test, and isometric standing hip abduction are other options to target the anterior GMed segment, while isometric standing hip abduction can be used for the posterior GMed segment. For the middle GMed segment, the single leg bridge; side-lying hip abduction with hip internal rotation; lateral step-up; standing hip abduction on stance or swing leg with added resistance; and resisted side-step were the best options for generating at least high activity. Standing isometric hip abduction and different variations of the hip hitch/ pelvic drop exercise generated at least high activity in all GMin segments, while side-lying hip abduction, the dip test, single leg bridge and single leg squat can also be used for targeting the posterior GMin segment.

Conclusion

The findings from this review provide the clinician with confidence in exercise prescription for targeting individual GMed and GMin segments for potential strengthening following injury or ageing.

Level of Evidence

Level 1.

What is known about the subject

Previous reviews on GMed exercises have been based on single electrode, surface EMG measures at middle GMed segment. It is not known whether these exercises effectively target the other segments of GMed or the GMin at a sufficient intensity for strengthening.

What this study adds to existing knowledge

This review provides the clinician with confidence in exercise prescription of common therapeutic exercises to effectively target individual GMed and GMin segments for potential strengthening.

Strength development and non-contact lower limb injury in academy footballers across age groups

Non-contact lower limb injuries are common in academy football. Yet, the impact these injuries have on strength development in academy footballers remains unclear. This study aimed to investigate the impact of non-contact lower limb injury on hip, groin, and knee flexor strength development in male academy youth footballers. Furthermore, this study: reports normative strength data of emerging field-based tests that can be easily deployed in football academies; explores the effect of age on injury occurrence; and highlights the number of days lost from injury in male youth footballers. Assessments of hip adductor, abductor, and eccentric knee flexor strength were obtained from 195 academy football players during pre-season and at the end of season. In-season injuries were recorded by medical staff. Those footballers who sustained non-contact lower limb injury were compared with those who did not sustain a non-contact lower limb injury. No between-group differences were observed for any strength assessments when controlled for pre-season measures. Stronger footballers at pre-season experienced strength loses, while those weaker players gained strength across the season. Hip strength development was impaired in older age group footballers. Sustaining a non-contact lower limb injury had minimal impact on strength development. In the absence of in-season lower limb strength monitoring, development in academy youth footballers may not progress as expected, and in particular, stronger and older youth athletes may benefit from individualized strength training.

Preseason Hip/Groin Strength and HAGOS Scores Are Associated With Subsequent Injury in Professional Male Soccer Players

DESIGN

Prospective cohort.

OBJECTIVE

To explore the association between preseason assessments of (1) isometric hip adductor and abductor strength using a novel field test and (2) the Copenhagen Hip and Groin Outcome Score (HAGOS) and subsequent hip/groin injury in male professional soccer players.

METHODS

In total, 204 male elite soccer players from 10 professional A-League and English Football League Championship clubs underwent assessments of hip adductor and abductor strength and completed the HAGOS in the 2017-2018 preseason. All subsequent hip/groin injuries were reported by team medical staff. Data reduction was conducted using principal-component analysis. The principal component for the HAGOS and 3 principal components for strength and imbalance measures were entered, with age and prior hip/groin injury, into a multivariable logistic regression model to determine their association with prospectively occurring hip/groin injury.

RESULTS

Twenty-four players suffered at least 1 hip/groin injury throughout the 2017-2018 season. The principal component for between-limb abduction imbalance (peak strength in the preferred kicking limb - nonpreferred limb) (odds ratio [OR] = 0.58; 95% confidence interval [CI]: 0.38, 0.90; P = .011), the principal component for peak adduction and abduction strength (OR = 0.71; 95% CI: 0.51, 1.00; P = .045), and the principal component for the HAGOS (OR = 0.77; 95% CI: 0.62, 0.96; P = .022) were independently associated with a reduced risk of future hip/groin injury. Receiver operating characteristic curve analysis of the whole model revealed an area under the curve of 0.76, which indicates a fair combined sensitivity and specificity of the included variables but an inability to correctly identify all subsequently injured players.

CONCLUSION

Hip abduction imbalance favoring the preferred kicking limb, higher levels of hip adductor and abductor strength, and superior HAGOS values were associated with a reduced likelihood of future hip/groin injury in male professional soccer players. J Orthop Sports Phys Ther 2020;50(5):234-242. Epub 17 Sep 2019. doi:10.2519/jospt.2020.9022.

Segmental coordination and variability of change in direction in long-standing groin pain

BACKGROUND

Long-standing groin pain (LSGP) is a chronic painful condition resulting in both impaired performance and time loss from participation in multidirectional field sport.

RESEARCH QUESTION

What are the differences in intersegmental coordination strategy and variability of trunk-pelvic and thigh coupling during change of direction in subjects with athletic LSGP and asymptomatic control subjects?

METHODS

A motion analysis system was used to collect 3-D kinematic data of the continuous relative phase and the variability of the right and left leg hip. Thoracic-thigh segment data were also collected during multiple ipsilateral turns at a self-selected pace from 16 males with LSGP and 16 asymptomatic controls. It is worth mentioning that, for a more detailed analysis, we divided each cycle diagram into four phases. Independent T-tests were used to compare the two groups.

RESULTS

Subjects with LSGP demonstrate except in phase 2 of the left foot, more out-of-phase movement with both increased variabilities in right/ left thigh - pelvic coupling, right/ left thigh-thoracic, and pelvic- thoracic in every 4 phases and in the decoupling of segmental coordination.

SIGNIFICANCE

Decrease in coordination with higher variability is apparent in subjects with LSGP and this aberrant coordination may lead to unexpected compensatory strategies and control impairments.

Does athletic groin pain affect the muscular co-contraction during a change of direction

BACKGROUND

Groin pain is one of the common problems in multidirectional sports. It seems that abnormal muscular activity and improper movement strategy led to prolongation and high rate of this injury. Therefore, the aim of this study was to Comparing the Average amplitude of Electromyography (AEMG), co-contraction ratio (CCR) of selected thigh and thoracic muscle during turning in individuals with chronic groin pain and healthy individuals.

METHODS

Surface electromyography was collected from the internal oblique/transversus abdominis (IO/TrA), multifidus (MF), adductor Longus (AL) and gluteus Medius (GM) for AEMG and CCR analyzed in 16-males with LSGP and 16-controls in four motion phases during 11 cycles of gait coupled with turning.

RESULTS

Results revealed that in the AEMG apart from the third phase in the muscle of the IO/ Tr. A muscle and in the second phase in the MF muscle in the trunk and in the third phase in the muscle of the AL and the fourth phase in the GM foot Left There was a significant difference in other phases. There was a significant difference in the CCR, except in the second phase of the trunk and the fourth phase of the left foot in the rest of the phases.

CONCLUSIONS

It seems that in athletes with LSGP, have selective muscular activation and CCR have during turning, that may be resulting in compensatory strategies and movement control defects, which may be a useful tool to predict LSGP occurrence in players with a history of groin pain.

Comparative Effects of 4 Single-Leg Squat Exercises in Subjects With Gluteus Medius Weakness

CONTEXT

Of the weight-bearing exercises, single-leg squats (SLSs) represent one of the most commonly used hip-strengthening exercises that require more gluteus medius (GMED) activity. To date, no studies have investigated how the 4 SLS exercises affect muscle imbalance of GMED, tensor fasciae latae (TFL), and adductor longus (AL), and kinematics of hip.

OBJECTIVE

To investigate the hip muscle activities, onset time, and kinematics during 4 different SLS exercises (unilateral squat, unilateral wall-squat [UWS], lateral step-down, and front step-down) in subjects with GMED weakness.

DESIGN

Repeated-measures experimental design.

SETTING

Research laboratory.

PARTICIPANTS

Twenty-two subjects (11 males and 11 females) participated in this study and were compared using 1-way repeated-measures analysis of variance.

MAIN OUTCOME MEASURES

Surface electromyography was used to measure the muscle activities and onset time of the GMED, TFL, and AL, and 3-dimensional motion tracking system was used to measure the hip adduction and internal/external rotation angles during SLS exercises. One-way repeated-measures analysis of variance was used at a significance level of P < .05.

RESULTS

The UWS produced higher GMED/TFL activity ratio and lower GMED/TFL onset time ratio than in the other 3 exercises (P < .05). No difference in GMED/AL activity ratio and GMED/AL onset time ratio was observed. The hip adduction angle was greater in UWS than in the other 3 exercises (P < .05). As for the hip internal/external rotation, lateral step-down exhibited higher hip internal rotation angle than front step-down (P < .05).

CONCLUSION

The UWS may be recommended as an effective exercise for the subjects with GMED weakness, but they should take care to avoid excessive hip adduction during the exercise.

Movement Patterns and Muscular Function Before and After Onset of Sports-Related Groin Pain: A Systematic Review with Meta-analysis

Background

Sports-related groin pain (SRGP) is a common entity in rotational sports such as football, rugby and hockey, accounting for 12–18 % of injuries each year, with high recurrence rates and often prolonged time away from sport.

Objective

This systematic review synthesises movement and muscle function findings to better understand deficits and guide rehabilitation.

Study Selection

Prospective and retrospective cross-sectional studies investigating muscle strength, flexibility, cross-sectional area, electromyographic activation onset and magnitude in patients with SRGP were included.

Search Methods

Four databases (MEDLINE, Web of Knowledge, EBSCOhost and EMBASE) were searched in June 2014. Studies were critiqued using a modified version of the Downs and Black Quality Index, and a meta-analysis was performed.

Results

Seventeen studies (14 high quality, 3 low quality; 8 prospective and 9 retrospective) were identified. Prospective findings: moderate evidence indicated decreased hip abduction flexibility as a risk factor for SRGP. Limited or very limited evidence suggested that decreased hip adduction strength during isokinetic testing at ~119°/s was a risk factor for SRGP, but no associations were found at ~30°/s or ~210°/s, or with peak torque angle. Decreased hip abductor strength in angular velocity in ~30°/s but not in ~119°/s and ~210°/s was found as a risk factor for SRGP. No relationships were found with hip internal or external rotation range of movement, nor isokinetic knee extension strength. Decreased isokinetic knee flexion strength also was a potential risk factor for SRGP, at a speed ~60°/s. Retrospective findings: there was strong evidence of decreased hip adductor muscle strength during a squeeze test at 45°, and decreased total hip external rotation range of movement (sum of both legs) being associated with SRGP. There was strong evidence of no relationship to abductor muscle strength nor unilateral hip internal and external rotation range of movement. Moderate evidence suggested that increased abduction flexibility and no change in total hip internal rotation range of movement (sum of both legs) were retrospectively associated with SRGP. Limited or very limited evidence (significant findings only) indicated decreased hip adductor muscle strength during 0° and 30° squeeze tests and during an eccentric hip adduction test, but a decrease in the isometric adductors-to-abductors strength ratio at speed 120°/s; decreased abductors-to-adductors activation ratio in the early phase in the moving leg as well as in all three phases in the weight-bearing leg during standing hip flexion; and increased hip flexors strength during isokinetic and decrease in transversus abdominis muscle resting thickness associated with SRGP.

Conclusions

There were a number of significant movement and muscle function associations observed in athletes both prior to and following the onset of SRGP. The strength of findings was hampered by the lack of consistent terminology and diagnostic criteria, with there being clear guides for future research. Nonetheless, these findings should be considered in rehabilitation and prevention planning.

Clinical Examination, Diagnostic Imaging, and Testing of Athletes With Groin Pain: An Evidence-Based Approach to Effective Management

Synopsis Groin pain is common in athletes who participate in multidirectional sports and has traditionally been considered a difficult problem to understand, diagnose, and manage. This may be due to sparse historical focus on this complex region in sports medicine. Until recently, there has been little agreement regarding terminology, definitions, and classification of groin pain in athletes. This has made clear communication between clinicians difficult, and the results of research difficult to interpret and implement into practice. However, during the past decade, the field has evolved rapidly, and an evidence-based understanding is now emerging. This clinical commentary discusses the clinical examination (subjective history, screening, physical examination); imaging; testing of impairments, function, and performance; and management of athletes with groin pain in an evidence-based framework. J Orthop Sports Phys Ther 2018;48(4):239-249. Epub 6 Mar 2018. doi:10.2519/jospt.2018.7850.

Hip Strength and Range of Movement Are Associated With Dynamic Postural Control Performance in Individuals Scheduled for Arthroscopic Hip Surgery

Study Design Cross-sectional. Background Hip pain is associated with reduced muscle strength and range of movement (ROM). These impairments may contribute to decreased postural stability and balance. The Star Excursion Balance Test (SEBT) is a reliable and valid method to measure dynamic postural control. Objectives To evaluate the association between SEBT performance and hip strength, hip ROM, trunk endurance, and group characteristics in individuals with hip pain. Methods One hundred eleven individuals with hip pain, scheduled for arthroscopic hip surgery, were matched with 62 healthy controls. Hip ROM and muscle strength, trunk endurance, and SEBT reach were measured prior to surgery. Data were analyzed for between-group differences using t tests, and associations between SEBT reach and hip strength, hip ROM, and population characteristics were evaluated with Pearson correlation coefficients and stepwise backward regression analyses. Results Star Excursion Balance Test performance (P<.01), hip strength (P<.01), and hip ROM (P<.05) were lower in the presurgery group compared to controls. In the presurgery group, when adjusted for height and weight, hip flexion strength and internal rotation ROM accounted for 44% of the variance in anteromedial SEBT reach. In the posteromedial direction, hip adduction strength and sex accounted for 53% of the variance. For the posterolateral direction, hip adduction and internal rotation strength accounted for 46% of reach variance. Conclusion The individuals who were scheduled for arthroscopic hip surgery were significantly weaker, had less hip mobility, and had reduced dynamic balance compared to controls. In this population, dynamic balance performance was associated with various hip strength and ROM measurements in a direction-specific manner. J Orthop Sports Phys Ther 2018;48(4):280-288. doi:10.2519/jospt.2018.7946.

Is stiffness related to athletic groin pain?

Athletic groin pain (AGP) is a common injury prevalent in field sports. One biomechanical measure that may be of importance for injury risk is stiffness. To date, [corrected] however, stiffness has not been examined in AGP. The primary aim was to determine whether AGP affects vertical and joint stiffness and if so, whether successful rehabilitation is associated with a change in stiffness. Sixty-five male patients with AGP and fifty male controls were recruited to this study. Assessment included a biomechanical examination of stiffness during a lateral hurdle hop test. Subjects with AGP were tested pre- and post-rehabilitation, while controls were tested once. AGP subjects were cleared for return to play in a median time of 9.14 weeks (5.14-29.0). Stiffness was significantly different at pre-rehabilitation in comparison with controls for three [corrected] of the ten stiffness values examined: ankle plantar flexor, knee extensor, hip abductor, and vertical stiffness (P <  .05, D = 0.38-0.81). [corrected]. Despite clearance for return to play, of these four variables, only hip abductor stiffness changed significantly from pre- to post-rehabilitation (P = .05, D = 0.36) [corrected] to become non-significantly different to the uninjured group (P = .23, D = 0.23). [corrected]. These findings suggest that hip abductor stiffness may represent a target for AGP rehabilitation. Conversely, given the clearance for return to play, the lower sagittal plane and vertical stiffness in the AGP group in comparison with the uninjured controls likely represents either a compensatory mechanism to reduce the risk of further injury or a consequence of neuromuscular detraining.

Adductor magnus: An EMG investigation into proximal and distal portions and direction specific action

Cadaveric studies indicate that adductor magnus is structurally partitioned into at least two regions. The aim of this study was to investigate the direction-specific actions of proximal and distal portions of adductor magnus, and in doing so determine if these segments have distinct functional roles. Fine-wire EMG electrodes were inserted into two portions of adductor magnus of 12 healthy young adults. Muscle activity was recorded during maximum voluntary isometric contractions (MVICs) across eight tests (hip flexion/extension, internal/external rotation, abduction, and adduction at 0°, 45°, and 90° hip flexion). Median activity within each action (normalized to peak) was compared between segments using repeated measures nonparametric tests (α = 0.05). An effect size (ES = z-score/√sample size) was calculated to determine the magnitude of difference between muscle segments. The relative contribution of each muscle segment differed significantly during internal rotation (P < 0.001; ES = 0.88) and external rotation (P = 0.003, ES = 0.79). The distal portion was most active during extension [median (interquartile range); 100(0)% MVIC)] and internal rotation [58(34)% MVIC]. The proximal portion was most active during extension [100(49)% MVIC] and adduction [59(64)%MVIC], with low level activity during external rotation [15(41)%MVIC]. This study suggests that adductor magnus has at least two functionally unique regions. Differences were most evident during rotation. The different direction-specific actions may imply that each segment performs separate roles in hip stability and movement. These findings may have implications on injury prevention and rehabilitation for adductor-related groin injuries, hamstring strain injury, and hip pathology. Clin. Anat. 31:535-543, 2018. © 2018 Wiley Periodicals, Inc.

The reliability of a maximal isometric hip strength and simultaneous surface EMG screening protocol in elite, junior rugby league athletes

OBJECTIVES

Firstly to describe the reliability of assessing maximal isometric strength of the hip abductor and adductor musculature using a hand held dynamometry (HHD) protocol with simultaneous wireless surface electromyographic (sEMG) evaluation of the gluteus medius (GM) and adductor longus (AL). Secondly, to describe the correlation between isometric strength recorded with the HHD protocol and a laboratory standard isokinetic device.

DESIGN

Reliability and correlational study.

METHODS

A sample of 24 elite, male, junior, rugby league athletes, age 16-20 years participated in repeated HHD and isometric Kin-Com (KC) strength testing with simultaneous sEMG assessment, on average (range) 6 (5-7) days apart by a single assessor. Strength tests included; unilateral hip abduction (ABD) and adduction (ADD) and bilateral ADD assessed with squeeze (SQ) tests in 0 and 45° of hip flexion.

RESULTS

HHD demonstrated good to excellent inter-session reliability for all outcome measures (ICC_(2,1)=0.76-0.91) and good to excellent association with the laboratory reference KC (ICC_(2,1)=0.80-0.88). Whilst intra-session, inter-trial reliability of EMG activation and co-activation outcome measures ranged from moderate to excellent (ICC_(2,1)=0.70-0.94), inter-session reliability was poor (all ICC_(2,1)<0.50).

CONCLUSIONS

Isometric strength testing of the hip ABD and ADD musculature using HHD may be measured reliably in elite, junior rugby league athletes. Due to the poor inter-session reliability of sEMG measures, it is not recommended for athlete screening purposes if using the techniques implemented in this study.

Lower extremity muscle activation onset times during the transition from double-leg stance to single-leg stance in anterior cruciate ligament reconstructed subjects

BACKGROUND

Previous studies mainly focused on muscles at the operated knee after anterior cruciate ligament reconstruction, less on muscles around other joints of the operated and non-operated leg. The aim of this study was to investigate muscle activation onset times during the transition from double-leg stance to single-leg stance in anterior cruciate ligament reconstructed subjects.

METHODS

Lower extremity muscle activation onset times of both legs of 20 fully returned to sport anterior cruciate ligament reconstructed subjects and 20 non-injured control subjects were measured during the transition from double-leg stance to single-leg stance in eyes open and eyes closed conditions. Analysis of covariance (ANCOVA) was used to evaluate differences between groups and differences between legs within both groups, while controlling for peak center of pressure velocity.

FINDINGS

Significantly delayed muscle activation onset times were found in the anterior cruciate ligament reconstructed group compared to the control group for gluteus maximus, gluteus medius, vastus medialis obliquus, medial hamstrings, lateral hamstrings and gastrocnemius in both eyes open and eyes closed conditions (P<.05). Within the anterior cruciate ligament reconstructed group, no significant different muscle activation onset times were found between the operated and non-operated leg (P>.05).

INTERPRETATION

Despite completion of rehabilitation and full return to sport, the anterior cruciate ligament reconstructed group showed neuromuscular control deficits that were not limited to the operated knee joint. Clinicians should focus on relearning multi-segmental anticipatory neuromuscular control strategies after anterior cruciate ligament reconstruction.

Electromyographic Analysis of the Hip Extension Pattern in Visually Impaired Athletes

The objective of the study was to determine the order of muscle recruitment during the active hip joint extension in particular positions in young visually impaired athletes. The average recruitment time (ART) of the gluteus maximus (GM) and the hamstring muscle group (HMG) was assessed by the means of surface electromyography (sEMG). The sequence of muscle recruitment in the female and male group was also taken into consideration. This study followed a prospective, cross - sectional, randomised design, where 76 visually impaired athletes between the age of 18-25 years were enrolled into the research and selected on chosen inclusion and exclusion criteria. Finally, 64 young subjects (32 men and 32 women) were included in the study (age: 21.1 ± 1.05 years; body mass: 68.4 ± 12.4 kg; body height: 1.74 ± 0.09 m; BMI: 22.20 ± 2.25 kg/m2). All subjects were analysed for the ART of the GM and HMG during the active hip extension performed in two different positions, as well as resting and functional sEMG activity of each muscle. Between gender differences were comprised and the correlations between the ART of the GM and HMG with their functional sEMG activity during hip extension in both positions were shown. No significant differences between the ART of the GM and HMG were found (p>0.05). Furthermore, there was no significant difference of ART among both tested positions, as well in male as female subjects (p>0.05).

Risk factors for groin injury in sport: an updated systematic review

BACKGROUND

The identification of risk factors for groin injury in sport is important to develop and implement injury prevention strategies.

OBJECTIVE

To identify and evaluate the evidence examining risk factors for groin injury in sport.

MATERIAL AND METHODS

Nine electronic databases were systematically searched to June 2014. Studies selected met the following criteria: original data; analytic design; investigated a risk factor(s); included outcomes for groin injury sustained during sport participation. The Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines were followed and two independent authors assessed the quality and level of evidence with the Downs and Black (DB) criteria and Oxford Centre of Evidence-Based Medicine model, respectively.

RESULTS

Of 2521 potentially relevant studies, 29 were included and scored. Heterogeneity in methodology and injury definition precluded meta-analyses. The most common risk factors investigated included age, hip range of motion, hip adductor strength and height. The median DB score across studies was 11/33 (range 6-20). The majority of studies represented level 2 evidence (cohort studies) however few considered the inter-relationships between risk factors. There is level 1 and 2 evidence that previous groin injury, higher-level of play, reduced hip adductor (absolute and relative to the hip abductors) strength and lower levels of sport-specific training are associated with increased risk of groin injury in sport.

CONCLUSIONS

We recommended that investigators focus on developing and evaluating preparticipation screening and groin injury prevention programmes through high-quality randomised controlled trials targeting athletes at greater risk of injury.

Normative adductor squeeze test values in elite junior rugby union players

OBJECTIVE

To establish normative adductor squeeze test (AST) values in elite junior rugby union players and investigate if differences existed between field position units and categorizations.

DESIGN

Cross-sectional study.

SETTING

National underage screening camp.

PARTICIPANTS

One hundred four healthy players attending an under-19 and under-18 national musculoskeletal and fitness screening camp. Players had no history of surgery, no self-reported history of groin or pelvic pain in either limb and no other lower limb injury in the past 3 months, and no pain reported during the testing procedure.

MAIN OUTCOME MEASURES

The AST in 3 positions of hip flexion (0, 45, and 90 degrees), position unit, and categorizations.

RESULTS

The highest AST values were observed at 45 degrees of hip flexion in all field position categories. No differences were observed between position units and categorizations.

CONCLUSIONS

Normative AST values in an elite junior rugby union population were established in this investigation. Clinically, the sports medicine professional may use these results in making decisions on the management of both symptomatic and asymptomatic players.

The relationship between the piriformis muscle, low back pain, lower limb injuries and motor control training among elite football players

OBJECTIVES

Australian Football League (AFL) players have a high incidence of back injuries. Motor control training to increase lumbopelvic neuromuscular control has been effective in reducing low back pain (LBP) and lower limb injuries in elite athletes. Control of pelvic and femoral alignment during functional activity involves the piriformis muscle. This study investigated (a) the effect of motor control training on piriformis muscle size in AFL players, with and without LBP, during the playing season, and (b) whether there is a relationship between lower limb injury and piriformis muscle size.

DESIGN

Stepped-wedge intervention.

METHODS

46 AFL players participated in a motor control training programme consisting of two 30min sessions per week over 7-8 weeks, delivered across the season as a randomised 3 group single-blinded stepped-wedge design. Assessment of piriformis muscle cross-sectional area (CSA) involved magnetic resonance imaging (MRI) at 3 time points during the season. Assessment of LBP consisted of player interview and physical examination. Injury data were obtained from club records.

RESULTS

An interaction effect for Time, Intervention Group and LBP group (F=3.7, p=0.03) was found. Piriformis muscle CSA showed significant increases between Times 1 and 2 (F=4.24, p=0.046), and Times 2 and 3 (F=8.59, p=0.006). Players with a smaller increase in piriformis muscle CSA across the season had higher odds of sustaining an injury (OR=1.08).

CONCLUSIONS

Piriformis muscle size increases across the season in elite AFL players and is affected by the presence of LBP and lower limb injury. Motor control training positively affects piriformis muscle size in players with LBP.