A comparison of surface and fine wire EMG recordings of gluteus medius during selected maximum isometric voluntary contractions of the hip

Electromyographic (EMG) studies into gluteus medius (GMed) typically involve surface EMG electrodes. Previous comparisons of surface and fine wire electrode recordings in other muscles during high load isometric tasks suggest that recordings between electrodes are comparable when the muscle is contracting at a high intensity, however, surface electrodes record additional activity when the muscle is contracting at a low intensity. The purpose of this study was to compare surface and fine wire recordings of GMed at high and low intensities of muscle contractions, under high load conditions (maximum voluntary isometric contractions, MVICs). Mann–Whitney U tests compared median electrode recordings during three MVIC hip actions; abduction, internal rotation and external rotation, in nine healthy adults. There were no significant differences between electrode recordings in positions that evoked a high intensity contraction (internal rotation and abduction, fine wire activity >77% MVIC; effect size, ES 0.277). During external rotation, the intensity of muscle activity was low (4.2% MVIC), and surface electrodes recorded additional myoelectric activity (ES = 0.67, p = 0.002). At low levels of muscle activity during high load isometric tasks, the use of surface electrodes may result in additional myoelectric recordings of GMed, potentially reflective of cross-talk from surrounding muscles

Technical application and the level of discomfort associated with an intramuscular electromyographic investigation into gluteus minimus and gluteus medius

Our current theoretical understanding of gluteus minimus (GMin) and gluteus medius (GMed) function is primarily based on cadaveric studies and biomechanical modelling. There is an absence of electromyographic (EMG) research that aims to verify this understanding, particularly in relation to the potentially unique functional roles of structurally distinct segments within GMin (anterior and posterior) and GMed (anterior, middle and posterior). The aim of this paper is to provide a comprehensive technical description for inserting intramuscular EMG electrodes into uniquely oriented segments of GMin and GMed; and to report the levels of discomfort associated with gluteal intramuscular electrode insertions. Fifteen healthy volunteers took part in a series of walking trials after intramuscular EMG electrodes were inserted into segments of GMin (×2) and GMed (×3) according to previously verified guidelines. Visual analogue scores following walking trials at comfortable and fast speed indicate that discomfort levels associated with these insertions were low (2.4. ±. 1.4 and 1.6. ±. 0.7 respectively). The technical descriptions and illustrations provided in this paper will allow trained intramuscular electromyographers to insert electrodes into these muscle segments with confidence

Development of Clinical Rating Criteria for Tests of Lumbopelvic Stability

Background. Lumbopelvic stability (LPS) is regarded as important for injury prevention, yet there are few reliable or valid tests that can be used in the clinical assessment of LPS. Three dynamic functional tests were identified that assess LPS in multiple planes of motion: dip test (DT), single leg squat (SLS), and runner pose test (RPT). Existing rating criteria for SLS have limited reliability and rating criteria for DT and RPT have not been established. Objective. To develop rating criteria for three clinical tests of LPS. Design. Qualitative research: focus group. Method. A focus group of five expert physiotherapists used qualitative methods to develop rating criteria for the three clinical tests. Results. Detailed rating criteria were established for the three tests. Each key factor considered important for LPS had characteristics described that represented both good and poor LPS. Conclusion. This study established rating criteria that may be used to clinically assess LPS

FATIGUE INDUCED POSTURAL CHANGES IN AUSTRALIAN RULES FOOTBALL PLAYERS WITH AND WITHOUT A HISTORY OF HAMSTRING INJURY

The purpose of this study was to explore the influence of game fatigue on sprint mechanics in Australian Rules Football (ARF) players with and without a history of hamstring strain injury (HSI). Thirty community level ARF players, 11 with a HSI within the previous two years, undertook a game protocol simulating the running requirements of an ARF match. Three-dimensional kinematic trunk and lower limb data of 10 sprints were collected prior to the game protocol, and at the end of each simulated quarter, allowing the influence of game fatigue to be assessed. In players with a history of HSI, joint angle data revealed changes in sagittal plane hip and lumbar spine position with increasing fatigue. Persistent hamstring dysfunction may be revealed as the athlete progresses through a game and has potential implications for injury recurrence

Gluteus medius: an intramuscular EMG investigation of anterior, middle and posterior segments during gait

Previous electromyographic (EMG) studies of gluteus medius (GMed) have not accurately quantified the function of the three proposed structurally and functionally unique segments (anterior, middle and posterior). Therefore this study used anatomically verified locations for intramuscular electrode recordings in three segments of GMed to determine whether the segments are functionally independent. Bipolar fine wire electrodes were inserted into each segment of GMed in 15 healthy individuals. Participants completed a series of four walking trials, followed by maximum voluntary isometric contractions (MVICs) in five different positions. Temporal and amplitude variables for each segment were compared across the gait cycle using ANOVA. The relative contributions of each segment to the MVIC trials were compared with non-parametric tests. All segments showed a biphasic response during the stance phase of gait. There were no differences in amplitude variables (% MVIC) between segments, but the anterior segment had a later peak during both the first and second bursts. For the MVIC trials, there were significant differences in amplitude between segments in four of the five test positions. These data indicate that GMed is composed of three functionally independent segments. This study contributes to the theoretical understanding of the role of GMed

Gluteus minimus: an intramuscular EMG investigation of anterior and posterior segments during gait

Gluteus minimus is believed to consist of two structurally and functionally unique segments (anterior and posterior); however there is a lack of electromyography (EMG) research that attempts to verify current theoretical knowledge of this muscle. The purpose of this study was therefore to evaluate the function of gluteus minimus during gait, and to determine whether anterior and posterior segments are functionally independent. Bipolar fine wire intramuscular EMG electrodes were inserted into anterior and posterior gluteus minimus segments of fifteen healthy volunteers (9 males) according to previously verified guidelines. Participants completed a series of four walking trials, followed by maximum voluntary isometric contractions in five different positions. Temporal and amplitude variables for each segment were compared across the gait cycle with independent t-tests. The relative contribution of each segment to the maximum resisted trials was compared with Mann-Whitney U tests (α=0.05). Anterior and posterior segments were contracting at different relative intensities for three of the five maximum resisted trials (effect size=0.39 to 0.62,

Quadratus femoris: an EMG investigation during walking and running

Dysfunction of hip stabilizing muscles such as quadratus femoris (QF) is identified as a potential source of lower extremity injury during functional tasks like running. Despite these assumptions, there are currently no electromyography (EMG) data that establish the burst activity profile of QF during any functional task like walking or running. The objectives of this study were to characterize and compare the EMG activity profile of QF while walking and running (primary aim) and describe the direction specific action of QF (secondary aim). A bipolar fine-wire intramuscular electrode was inserted via ultrasound guidance into the QF of 10 healthy participants (4 females). Ensemble curves were generated from four walking and running trials, and normalized to maximum voluntary isometric contractions (MVICs). Paired t-tests compared the temporal and amplitude EMG variables. The relative activity of QF in the MVICs was calculated. The QF displayed moderate to high amplitude activity in the stance phase of walking and very high activity during stance in running. During swing, there was minimal QF activity recorded during walking and high amplitudes were present while running (run vs walk effect size = 4.23,

A novel device to assess hip strength: Concurrent validity and normative values in male athletes

Objectives To assess concurrent validity of the new, novel externally-fixed dynamometer (GroinBar) with hand-held dynamometry (HHD); to provide normative GroinBar scores for elite Australian rules football (AFL) and football (Soccer) players; and to evaluate preliminary predictive validity of the GroinBar and HHD in this population by comparing strength results with patient-reported outcome scores. Design Cross-sectional and reliability study Participants Total of 67 athletes, 36 AFL players and 31 football (Soccer) players Setting Elite AFL and football (Soccer) teams Main Outcome Measures The GroinBar system, HHD, The Copenhagen Hip and Groin Outcome Score (HAGOS) Questionnaire. Results Moderate to good correlations were identified between the GroinBar and HHD strength tests for hip adduction and abduction in the long lever position (rs 0.53 – 0.71). Normative values of the GroinBar and HHD for both AFL and football (Soccer) players were obtained. Neither the GroinBar or HHD strength measures differed between players with groin problems and those without. Conclusion This externally fixed strength testing device, the GroinBar, may provide a robust method of athlete monitoring and screening that does not rely on tester experience and strength. Normative values are documented for hip adduction and abduction strength in elite male athletes

Gluteal loading versus sham exercises to improve pain and dysfunction in postmenopausal women with greater trochanteric pain syndrome: a randomized controlled trial

The aim of the current study was to determine the effects of education with targeted or sham exercise on pain and function in postmenopausal women with greater trochanteric pain syndrome (GTPS).Conservative management of GTPS is poorly described, and to date, there have been no studies on education with exercise as an intervention for GTPS. Ninety-four postmenopausal women with GTPS were recruited to participate in this study.Participants were randomized to receive one of two 12-week exercise programs (GLoBE vs. sham). Participants received education on avoiding tendon compression with appropriate activity modification. The Victorian Institute of Sport Assessment-Gluteal tendon (VISA-G) was examined at baseline, 12, and 52 weeks. Secondary outcomes included hip pain and function questionnaires (Hip dysfunction and Osteoarthritis Outcome Score (HOOS), Oxford Hip Score (OHS), and Lateral Hip Pain questionnaire), a global rating of change in symptom questionnaire, and a quality of life measure (Assessment of Quality of Life [AQoL]-8D). Differences between groups were analyzed using intention to treat with analysis of covariance, per-protocol analysis, and responder analysis.Responders to the GLoBE intervention had significantly better VISA-G, HOOS, OHS, and lateral hip pain questionnaire scores compared to responders in the sham group. However, intention to treat analyses showed no between-group differences for the GLoBE intervention and sham exercise groups. Significant improvement in VISA-G score was found for both programs at 12- and 52-weeks time points (p

A comparison of gluteus medius, gluteus minimus and tensor facia latae muscle activation during gait in post-menopausal women with and without greater trochanteric pain syndrome

The effect of greater trochanteric pain syndrome (GTPS) on gluteus medius (GMed) and minimus (GMin) activation in post-menopausal women is unknown. The aim of this study was to compare segmental muscle activation and variability of the GMed, GMin and tensor fascia latae (TFL) during gait in post-menopausal women with and without GTPS. Intramuscular electrodes were inserted into segments of GMin (x2) and GMed (x3) and a surface electrode placed on TFL. Ten control participants and 8 with GTPS completed six walking trials. Peak amplitude, average amplitude and time to peak from each phase of the gait cycle (0–30%, 30%- toe off (TO), total stance and swing) were compared between groups using independent t-tests and effect-size (ES) calculations. Variability of muscle activation was calculated using the mean coefficient of variation (CV). Reversal of anterior GMin electromyographic burst pattern and greater average muscle activity was found in the GTPS group compared to controls: 0-TO for anterior GMin (p < 0.05), anterior and middle GMed (p < 0.01); 0–30% for posterior GMin (p < 0.01) and GMed (p < 0.05). No significant differences were identified in TFL. Overall, this study found increased segmental gluteal muscle activation, decreased hip abduction strength, and reduced variability in muscle activation in post-menopausal women with GTPS, compared with controls