Article

EMG Activation Levels of the 3 Gluteus Medius Subdivisions During Manual Strength Testing.

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Abstract

Study Design: Cross-sectional. Context: Gluteus medius (GM) muscle dysfunction is associated with overuse injury. The GM is functionally composed of 3 separate subdivisions: anterior, middle, and posterior. Clinical assessment of the GM subdivisions is relevant to detect strength and activation deficits and guide specific rehabilitation programs. However, the optimal positions for assessing the strength and activation of these subdivisions are unknown. Objective: The first aim was to establish which strength-testing positions produce the highest surface electromyography (sEMG) activation levels of the individual GM subdivisions. The second aim was to evaluate differences in sEMG activation levels between the tested and contralateral (stabilizing) leg. Method: Twenty healthy physically active male subjects participated in this study. Muscle activity usingsEMG was recorded for the GM subdivisions in 8 different strength-testing positions and analyzed using repeated-measures analysis of variance. Results: Significant differences between testing positions for all 3 GM subdivisions were found. There were significant differences between the tested and the contralateral anterior and middle GM subdivisions (P < .01). The posterior GM subdivision showed no significant difference (P = .154). Conclusion: Side-lying in neutral and side-lying with hip internal rotation are the 2 positions recommended to evaluate GM function and guide specific GM rehabilitation.

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... The neuromuscular activity was recorded by surface electromyography (EMG) from the anterior, middle, and posterior portions of the GM. With the participant standing, the surface electrodes for the anterior region were placed at 50% of the distance between the anterosuperior iliac spine and the greater trochanter for the anterior fiber of the GM, the electrodes for the middle fibers were placed at 50% of the distance between the greater trochanter and the iliac crest, and the electrodes for the posterior fibers were placed at 33% of the distance between the posterior ilium and the greater trochanter (Otten et al., 2015). Electrodes were placed after the skin was FIGURE 2 | Crutch locomotion patterns. ...
... shaved and cleaned according to the "Surface Electromyography for the Non-Invasive Assessment of Muscles" guidelines (Hermens et al., 2000). After the placement of each electrode, the participant was requested to perform a maximal isometric test to check the selective action of the GM according to the sensor placement (Semciw et al., 2014;Otten et al., 2015). The quality of the signal was checked visually before any recording. ...
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Prospective cohort. To determine if Star Excursion Balance Test (SEBT) reach distance was associated with risk of lower extremity injury among high school basketball players. Although balance has been proposed as a risk factor for sports-related injury, few researchers have used a dynamic balance test to examine this relationship. Prior to the 2004 basketball season, the anterior, posteromedial, and posterolateral SEBT reach distances and limb lengths of 235 high school basketball players were measured bilaterally. The Athletic Health Care System Daily Injury Report was used to document time loss injuries. After normalizing for lower limb length, each reach distance, right/left reach distance difference, and composite reach distance were examined using odds ratio and logistic regression analyses. The reliability of the SEBT components ranged from 0.82 to 0.87 (ICC3,1) and was 0.99 for the measurement of limb length. Logistic regression models indicated that players with an anterior right/left reach distance difference greater than 4 cm were 2.5 times more likely to sustain a lower extremity injury (P<.05). Girls with a composite reach distance less than 94.0% of their limb length were 6.5 times more likely to have a lower extremity injury (P<.05). We found components of the SEBT to be reliable and predictive measures of lower extremity injury in high school basketball players. Our results suggest that the SEBT can be incorporated into preparticipation physical examinations to identify basketball players who are at increased risk for injury.
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This brief review examines some of the methods used to infer central control strategies from surface electromyogram (EMG) recordings. Among the many uses of the surface EMG in studying the neural control of movement, the review critically evaluates only some of the applications. The focus is on the relations between global features of the surface EMG and the underlying physiological processes. Because direct measurements of motor unit activation are not available and many factors can influence the signal, these relations are frequently misinterpreted. These errors are compounded by the counterintuitive effects that some system parameters can have on the EMG signal. The phenomenon of crosstalk is used as an example of these problems. The review describes the limitations of techniques used to infer the level of muscle activation, the type of motor unit recruited, the upper limit of motor unit recruitment, the average discharge rate, and the degree of synchronization between motor units. Although the global surface EMG is a useful measure of muscle activation and assessment, there are limits to the information that can be extracted from this signal.
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Context Gluteus medius (GM) contraction during single-leg stance prevents the contralateral pelvis from “dropping,” providing stability for lower extremity motion. Objective To determine which combination of hip rotation and abduction exercise results in the greatest activity of the GM and whether the GM responds to increased loads in these exercises. Design and Setting Repeated measures, laboratory. Subjects 20 healthy volunteers. Interventions Resistance (2.26 and 4.53 kg) was provided to 3 variations of a single-leg-stance exercise: hip abduction only, abduction-internal rotation (ABD-IR), and abduction-external rotation. Measurements Muscle activity was recorded from the anterior and middle portions of the GM using surface electromyography. Results ABD-IR produced the most activity in the anterior and middle sections of the GM muscle. The 4.53-kg load produced significantly more activity than the 2.26-kg load ( P < .05). Conclusions The GM is most active when performing abduction and internal rotation of the hip. This information could be used to develop GM-strengthening exercises.
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Bracing and rehabilitation are common aspects of an ankle treatment regimen. Recent evidence suggests that bracing and taping are effective in restricting ankle motion to within normal inversion/eversion ranges. They also improve kinesthesia and neuromuscular response, and decrease the velocity of inversion movements. Rehabilitation studies suggest that strength and balance training of the uninjured limb may be useful in facilitating recovery of the injured limb. It has also been demonstrated that daily balance training using wobble boards reduces the risk of further injury. Copyright © 2004 by Elsevier Science (USA).
Article
To evaluate the effect of soft and semirigid ankle orthoses on dynamic balance assessed using Star Excursion Balance Test in patients with functional ankle instability compared with healthy individuals. Non-experimental, observational study with multiple-factor design, including group (functional ankle instability and healthy) as the between-subjects factor and orthotics condition (no orthosis, soft orthosis and semirigid orthosis) as the within-subjects factor. Sixteen unilateral functional ankle instability patients and a group of 16 healthy control individuals, matched for age, height and weight, participated in the study. Dynamic balance was tested with and without wearing ankle orthosis. Reach distance of participants in 3 bracing conditions were measured in anteromedial, medial and posteromedial directions of Star Excursion Balance Test. Average of 3 trials in 3 measured directions, normalized to leg length of each participant, was used for statistical analysis. There were no differences among orthotics conditions in healthy people. However, normalized reach distance increased from no-orthosis to semirigid to soft orthoses in FAI patients. Differences were significant between soft and no-orthosis (13% in anteromedial, 14% in medial and 15% in posteromedial direction p=0.01) and between semirigid and no-orthosis (10% in anteromedial, 8.5% in medial and 8.5% in posteromedial direction, p=0.01) conditions in all 3 measured directions. The difference between soft and semirigid orthoses was significant (6% difference, p<0.05) only in PM direction. Ankle orthoses improve reach distance in functional ankle instability patients in various reach directions. Soft orthosis has a more pronounced effect on dynamic balance, especially in posteromedial direction, compared with semirigid orthosis.
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Background Groin pain is a common injury among football code athletes. The repetitive turning, twisting and kicking involved in such sports place supra-physiological stresses through the pelvic region. It has been suggested that rehabilitation of chronic groin pain requires specific sequencing of muscle activation to be effective. This has been identified as being a difference in subjects with groin and sacroiliac joint pain during lower limb movement.AimsThe aims of this paper were to; (1) identify any differences in muscle activation before and during an active straight leg raise between football code groin sufferers and controls and to (2) highlight any differences in muscle activity between the symptomatic and asymptomatic sides in the groin sufferers before and during an active straight leg raise.MethodologyNine subjects with groin pain and nine matched controls (matched according to age, weight and height) were used. Surface electromyogenic (EMG) electrodes were placed on six bilateral muscle groups – rectus femoris, biceps femoris, adductor longus, internal oblique, multifidus and gluteus medius. Movement was qualified with an active motion tracking system, while the subject lay on two force plates and performed an active straight leg raise manoeuvre. EMG, force and pelvic motion was analysed to demonstrate any muscle activation differences between the symptomatic and asymptomatic group.ResultsA significant difference was found between the symptomatic and asymptomatic limbs in both ipsilateral and contralateral adductor longus muscles (p
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Verbal encouragement (VE) is commonly used to encourage patients to perform to their maximum potential during exercise sessions or for various assessment procedures. This controlled trial investigated the effectiveness of VE during a motor endurance performance. Subjects in the experimental (n = 32) and control group (n = 26) performed two trials of a leg-holding task, one on each leg. The control group were simply timed, while the experimental group performed one trial in the manner of the control group and one where they were verbally encouraged. These subjects thus acted as their own control. Results of a MANOVA showed that the size of effect was different between the two leg-holding trials depending upon the group (F(1,50) = 12.59, p < 0.001). Verbal encouragement significantly increased performance compared to the control group by 39% and by 33.5% compared to the subject's own control trial. Results are discussed in terms of the previous literature and suggestions are made for future investigations.
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The anatomy of the hip abductors has not been comprehensively examined, yet is important to understanding function and pathology in the gluteal region. For example, pathology of the hip abductor muscle-tendon complexes can cause greater trochanteric pain syndrome, and may be associated with gluteal atrophy and fatty infiltration. The purpose of this study was to investigate the detailed morphology of gluteus medius (GMed), gluteus minimus (GMin), and tensor fascia lata (TFL), and determine whether the muscles comprised anatomical compartments. The gluteal region from 12 cadavers was dissected and data collected on attachment sites, volume, fascicular and tendinous anatomy, and innervation. Three sites of GMed origin were identified (gluteal fossa, gluteal aponeurosis, and posteroinferior edge of the iliac crest) and the distal tendon had lateral and posterior parts. GMed was the largest in volume (27.6 ± 11.6 cm(3) ; GMin 14.1 ± 11.1 cm(3) ; TFL 1.8 ± 0.8 cm(3) ). Fascicles of GMin originated from the gluteal fossa, inserting onto the deep surface of its distal tendon and the hip joint capsule. TFL was encapsulated in the fascia lata, having no bony attachment. Primary innervation patterns varied for GMed, with three or four branches supplying different regions of muscle. Distinct secondary nerve branches entered four regions of GMin; no differential innervation was observed for TFL. On the basis of architectural parameters and innervation, GMed, and GMin each comprise of four compartments but TFL is a homogenous muscle. It is anticipated that these data will be useful for future clinical and functional studies of the hip abductors. Clin. Anat. 00:000-000, 2013. © 2013 Wiley Periodicals, Inc.
Article
Introduction Exercise programmes are used in the prevention and treatment of adductor-related groin injuries in soccer; however, there is a lack of knowledge concerning the intensity of frequently used exercises. Objective Primarily to investigate muscle activity of adductor longus during six traditional and two new hip adduction exercises. Additionally, to analyse muscle activation of gluteals and abdominals. Materials and methods 40 healthy male elite soccer players, training >5 h a week, participated in the study. Muscle activity using surface electromyography (sEMG) was measured bilaterally for the adductor longus during eight hip adduction strengthening exercises and peak EMG was normalised (nEMG) using an isometric maximal voluntary contraction (MVC) as reference. Furthermore, muscle activation of the gluteus medius, rectus abdominis and the external abdominal obliques was analysed during the exercises. Results There were large differences in peak nEMG of the adductor longus between the exercises, with values ranging from 14% to 108% nEMG (p<0.0001). There was a significant difference between legs in three of the eight exercises (35–48%, p<0.0001). The peak nEMG results for the gluteals and the abdominals showed relatively low values (5–48% nEMG, p<0.001). Conclusions Specific hip adduction exercises can be graded by exercise intensity providing athletes and therapists with the knowledge to select appropriate exercises during different phases of prevention and treatment of groin injuries. The Copenhagen Adduction and the hip adduction with an elastic band are dynamic high-intensity exercises, which can easily be performed at any training facility and could therefore be relevant to include in future prevention and treatment programmes.
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Study design: Within-subject, repeated-measures design. Objectives: To determine the influence of pelvis position and hip angle on activation of the hip abductors while performing the clam exercise. Background: Therapeutic exercises are regularly employed to strengthen the hip abductors to improve lower-limb and pelvis stability. While previous studies primarily have compared the activity of hip abductor muscles between various exercises, few studies have examined the influence of varying the techniques of particular exercises on the relative activation of hip abductor muscles. Such information could be used to facilitate appropriate exercise instruction. Methods: Muscle activation in 17 healthy, asymptomatic volunteers during 6 variations of the clam exercise was analyzed with surface electromyography. Electromyographic signals were recorded from the gluteus maximus, gluteus medius, and tensor fasciae latae. Normalized data were examined using 2-way, repeated-measures analyses of variance. Results: The magnitude of gluteus maximus and gluteus medius activation was significantly greater when the pelvis was in neutral rather than reclined. Furthermore, gluteus medius activation was greatest when the hip was flexed to 60°. Activation of the tensor fasciae latae was not influenced by pelvis position or hip angle. Conclusion: A neutral pelvis position is advocated to optimize recruitment of the gluteus maximus and gluteus medius during the clam exercise. Increasing the hip flexion angle increases activation of the gluteus medius. Tensor fasciae latae activity was relatively low and generally unaffected by variations of the clam exercise.
Article
Symptomatic external snapping hip can be a long-standing condition affecting physical function in younger people between 15-40 years. Gluteal weakness has been suggested to be associated with the condition. The aim of this study was to investigate whether eccentric hip abduction strength is decreased in patients with external snapping hip compared with healthy matched controls, and to examine isometric hip abduction, adduction, extension, flexion, internal rotation, and external rotation in patients with external snapping hip and matched controls. Thirteen patients with external snapping hip were compared with 13 healthy matched controls in a cross-sectional study design. The mean age of the patients was 25.5 ± 3.4 years and the mean age of the controls was 25.6 ± 2.6 years. Eccentric and isometric strength were assessed with a handheld dynamometer, using reliable test procedures. Eccentric hip abduction strength was 16% lower in patients with external snapping hip compared with healthy matched controls (1.50 ± 0.47 Nm/kg versus 1.82 ± 0.48 Nm/kg, P = 0.01). No other strength differences were measured between patients and controls (P > 0.05). Eccentric hip abductor weakness was present in patients with symptomatic external snapping hip compared with healthy matched controls.
Article
To determine the effect of ankle braces on kicking accuracy, speed, and agility in competitive, nonelite soccer players. We hypothesized that the use of ankle bracing would significantly decrease performance in soccer-specific drills immediately after use but not after acclimation to the brace. A prospective randomized controlled trial. University. Twenty healthy recreational adult soccer players (5 men and 15 women; mean age, 23 ± 4.8 years) without a history of lower extremity injury in the past 6 months. All the subjects completed the study. The subjects completed a set of performance measures (ie, accuracy shooting at a target, 40-yard dash, S180° run, and T test) with an McDavid 199 Lightweight ankle brace (test subjects) and without an ankle brace (control subjects) during 2 testing sessions spaced 7-10 days apart. Between the 2 testing sessions, the subjects wore the ankle brace on at least 4 occasions while participating in athletic activities to ensure that a learning effect occurred. Outcomes included kicking accuracy (accuracy shooting at a target) and speed and agility (time to complete a 40-yard dash, S180° run, and T test). No significant difference in performance was found for the accuracy in shooting at a target, 40-yard dash, S180° run, and T test (P > .05) with and without an ankle brace during a session and between sessions. Ankle braces did not significantly affect performance in speed, agility, or kicking accuracy in healthy, competitive, recreational soccer athletes.
Article
Guidelines for assessing the function of gluteus minimus and gluteus medius with electromyography (EMG) traditionally offer one electrode placement site per muscle. However, anatomical studies suggest that there are two uniquely oriented segments within gluteus minimus (anterior and posterior), and three within gluteus medius (anterior, middle, and posterior) with potential for independent function. Assessment of these muscles with one electrode may therefore provide only a limited account of their role. Thus, the aim of this cadaveric study was to verify guidelines for placing intramuscular electrodes into two uniquely oriented segments of gluteus minimus, and three segments of gluteus medius. The guidelines were developed with reference to anatomical reports, cadaveric observation and real-time ultrasound imaging in vivo. Five cadaveric gluteal regions were marked for intramuscular electrode insertions based on these guidelines. Intramuscular electrodes were inserted into the marked regions of gluteus minimus (2×) and gluteus medius (3×) with the aid of a 15 cm biopsy needle. Systematic dissection revealed that electrodes were successfully inserted into uniquely oriented segments of gluteus minimus and medius. The orientation of fascicles surrounding each electrode was also consistent with segmental descriptions in past anatomical research. The findings of this research suggest that the guidelines described may be used to assess the functional role of segments within gluteus minimus and medius in health and dysfunction using EMG. Finally, electromyographers intent on investigating the role of posterior gluteus minimus must be cautious of the superior gluteal neurovascular bundle. Clin. Anat., 2012. © 2012 Wiley Periodicals, Inc.
Article
Functional subdivisions are proposed to exist in the gluteus medius (GM) muscle. Dysfunction of the GM, in particular its functional subdivisions, is commonly implicated in lower limb pathologies. However, there is a lack of empirical evidence examining the role of the subdivisions of the GM. To compare the activation of the functional subdivisions of the GM (anterior, middle, and posterior) during isometric hip contractions. Single-session, repeated-measures observational study. University research laboratory. Convenience sample of 15 healthy, pain-free subjects. Subjects performed 3 maximal voluntary isometric contractions for hip abduction and internal and external rotation on an isokinetic dynamometer with simultaneous recording of surface electromyography (sEMG) activity of the GM subdivisions. sEMG muscle activity for each functional subdivision of the GM during each hip movement was analyzed using a 1-way repeated-measures ANOVA (post hoc Bonferroni). The response of GM subdivisions during the 3 different isometric contractions was significantly different (interaction effect; P = .003). The anterior GM displayed significantly higher activation across all 3 isometric contractions than the middle and posterior subdivisions (main effect; both P < .001). The middle GM also demonstrated significantly higher activation than the posterior GM across all 3 isometric contractions (main effect; P = .027). There was also significantly higher activation of all 3 subdivisions during both abduction and internal rotation than during external rotation (main effect; both P < .001). The existence of functional subdivisions in the GM appears to be supported by the findings. Muscle activation was not homogeneous throughout the entire muscle. The highest GM activation was found in the anterior GM subdivision and during abduction and internal rotation. Future studies should examine the role of GM functional subdivisions in subjects with lower limb pathologies.
Article
An ipsilateral hip adduction/abduction strength ratio of more than 90%, and hip adduction strength equal to that of the contralateral side have been suggested to clinically represent adequate strength recovery of hip adduction strength in athletes after groin injury. However, to what extent side-to-side symmetry in isometric hip adduction and abduction strength can be assumed in soccer players remains uncertain. To compare isometric hip adduction and abduction strength on the dominant and nondominant side in injury-free soccer players. Cross-sectional study; Level of evidence, 3. One hundred elite soccer players were included. Maximal unilateral isometric hip adduction and abduction strength on the dominant and nondominant side were measured with a handheld dynamometer, using a reliable test procedure. The dominant side was stronger than the nondominant side for both isometric hip adduction (2.45 ± 0.54 vs 2.37 ± 0.48 Nm/kg, P = .02) and hip abduction (2.35 ± 0.33 vs 2.25 ± 0.31 Nm/kg, P < .001), corresponding to a 3% and 4% difference, respectively. Isometric hip adduction was greater than isometric hip abduction for both the dominant (2.44 ± 0.53 vs 2.35 ± 0.33 Nm/kg, P = .04) and nondominant (2.37 ± 0.48 vs 2.26 ± 0.33 Nm/kg, P = .03) side. Isometric hip adduction/abduction ratio was not different between the dominant (1.04 ± 0.18) and nondominant (1.06 ± 0.17, P = .40) side. A post hoc analysis showed that isometric hip adduction/abduction ratio was significantly lower in players with groin pain during hip adduction testing compared with players with a pain-free test (0.80 ± 0.14, P < .001) The marginal difference between the dominant and the nondominant side is within the measurement variation of the test procedure, and contralateral isometric hip adduction strength can therefore be used as a simple clinical reference point of full recovery of hip adduction muscle strength in soccer players. Furthermore, it is suggested that the ipsilateral hip adduction/abduction strength ratio is used as a guideline for evaluating hip adduction strength recovery in soccer players with bilateral groin problems.
Article
The side-lying hip abduction exercise is one of the most commonly used exercises in rehabilitation to increase hip abduction strength, and is often performed without external loading. The aim of this study was to compare the effect of 6 weeks of side-lying hip abduction training, with and without external loading, on hip abduction strength in healthy subjects. Thirty-one healthy, physically active men and women were included in a randomised controlled trial and allocated to side-lying hip abduction training, with or without external loading. Training without external loading was performed using only the weight of the leg as resistance, whereas training with external loading was performed with a relative load corresponding to 10 repetition maximum. Hip abduction strength was measured pre- and post-intervention. Isometric and eccentric hip abduction strength of the trained leg increased after hip abduction training with external loading by 12% and 17%, respectively, (P<0.05). Likewise, isometric and eccentric hip abduction strength of the trained leg increased after hip abduction training without external loading by 11% and 23%, respectively, (P<0.001). The strength increases were not different between groups (P>0.05). Six weeks of side-lying hip abduction training, with or without external loading, increases isometric and eccentric hip abduction strength to the same extent.
Article
The purpose of this study was to determine the effect of prophylactic ankle bracing on the incidence of ankle injuries in a high school population of interscholastic volleyball players followed prospectively for one season. The study was designed to evaluate the effect of different types of ankle braces on the incidence of ankle sprains in high school volleyball players. There were 957 players in the group that wore braces and 42 in the control group who did not wear a brace. Information was collected on age, sex, previous injury, incidence of injury, and time off from play. Only the dominant ankle was studied. Overall, the use of a prophylactic ankle brace did not significantly alter the incidence of ankle sprains in high school volleyball players. However, in players without a previous ankle sprain, the use of an ankle brace did make a significant difference in two of the braced groups. The Active Ankle Trainer II and the Aircast Sports Stirrup protected volleyball players from a sprain only if they had not had a previous sprain. If the player had a history of a previous ankle sprain, these two brace groups did not protect the ankle from another ankle sprain (p < 0.05). In addition, there were significantly more injuries in the female group of players who wore a non-rigid brace versus those who wore a more rigid brace. This information may be helpful in deciding whether to recommend prophylactic ankle braces in volleyball players.
Article
Hip strength assessment plays an important role in the clinical examination of the hip and groin region. The primary aim of this study was to examine the absolute test-retest measurement variation concerning standardized strength assessments of hip abduction (ABD), adduction (ADD), external rotation (ER), internal rotation (IR), flexion (FLEX) and extension (EXT) using a hand-held dynamometer. Nine subjects (five males, four females), physically active for at least 2.5 h a week, were included. Twelve standardized isometric strength tests were performed twice with a 1-week interval in between by the same examiner. The test order was randomized to avoid systematic bias. Measurement variation between sessions was 3-12%. When the maximum value of four measurements was used, test-retest measurement variation was below 10% in 11 of the 12 individual hip strength tests and below 5% in five of the 12 tests. No systematic differences were present. Standardized strength assessment procedures of hip ABD, ER, IR, FLEX, with test-retest measurement variation below 5%, hip ADD below 6% and hip EXT below 8%, make it possible to determine even small changes in hip strength at the individual level.
Article
The purpose of this randomized controlled trial was to determine the effect of a 4-wk balance training program on static and dynamic postural control and self-reported functional outcomes in those with chronic ankle instability (CAI). Thirty-one young adults with self-reported CAI were randomly assigned to an intervention group (six males and 10 females) or a control group (six males and nine females). The intervention consisted of a 4-wk supervised balance training program that emphasized dynamic stabilization in single-limb stance. Main outcome measures included the following: self-reported disability on the Foot and Ankle Disability Index (FADI) and the FADI Sport scales; summary center of pressure (COP) excursion measures including area of a 95% confidence ellipse, velocity, range, and SD; time-to-boundary (TTB) measures of postural control in single-limb stance including the absolute minimum TTB, mean of TTB minima, and SD of TTB minima in the anteroposterior and mediolateral directions with eyes open and closed; and reach distance in the anterior, posteromedial, and posterolateral directions of the Star Excursion Balance Test (SEBT). The balance training group had significant improvements in the FADI and the FADI Sport scores, in the magnitude and the variability of TTB measures with eyes closed, and in reach distances with the posteromedial and the posterolateral directions of the SEBT. Only one of the summary COP-based measures significantly changed after balance training. Four weeks of balance training significantly improved self-reported function, static postural control as detected by TTB measures, and dynamic postural control as assessed with the SEBT. TTB measures were more sensitive at detecting improvements in static postural control compared with summary COP-based measures.
Article
We evaluated the effect of different ankle support de vices on athletic performance. Thirty varsity college athletes were tested with both ankles supported by taping, Swede-O brace, Kallassy brace or left unsup ported. The athletes performed four events: broad jump, vertical leap, 10 yard shuttle run, and 40 yard sprint. The events and appliances were randomized to prevent bias by fatigue. Compared to the results when no support was used, ankle taping resulted in a significant decreased perform ance in the vertical jump (4%), shuttle run (1.6%), and sprint (3.5%) (P < 0.05). Use of the Swede-O brace decreased performance in the vertical jump (4.6%), broad jump (3.6%), and time of the sprint (3.2%). Re sults using the Kallassy brace showed a decrease in the vertical jump (3.4%) when compared to no support. The test results of the shuttle run with taping were slower than the Kallassy brace (P < 0.05). Wearing the Swede-O brace caused the athletes' broad jump dis tance to decrease more than the Kallassy brace (P < 0.05). Subjective questionnaires supported the Kallassy brace as the most comfortable support and the one that decreased performance the least. Taping of the ankles is universally accepted for ankle prophylaxis. This study has shown a decrease in per formance when ankles are taped compared to ankles with no protection. Since the decreases in performance caused by ankle braces are minor, this should not be used as a criterion for selection of prophylactic support compared to taping.
Article
The purpose of this study was to compare the relative effectiveness of athletic taping and a semirigid orthosis in providing inversion-eversion range restriction before, during, and after a 3 hour volleyball practice. The effect of each support method on the subjects' vertical jumping ability was also assessed. Fourteen ankles were treated with both methods of support. Passive inversion-eversion range of motion was measured on an ankle stability test instrument during five testing sessions: 1) before support, 2) before exercise, 3) 20 minutes during exercise, 4) 60 minutes during exercise, and 5) after exercise. The two-way analysis of variance and posthoc comparisons revealed maximal losses in taping restriction for both inversion and eversion at 20 minutes into exercise. The orthosis demonstrated no mechanical restrictive failure until before and after exercise comparisons were made, and then only eversion range of motion was compromised. Neither support system affected subjects' vertical jumping ability. These results suggest that the semirigid orthosis may be more effective than taping in providing initial ankle protection and in guarding against ligamentous reinjury.
Article
The effects of ankle guards and taping on joint motion before, during, and after exercise were studied. Twelve league squash players played two matches, each lasting 1 hour. Two different ankle guards, and two types of tape applied by the same method, served as supports. A specially designed goniometer with electronic digital display (accuracy 1 degree) was used to determine joint range of motion: plantar-flexion and dorsiflexion, neutral inversion and eversion, plantar-flexed inversion and eversion. The results were statistically analyzed to determine the significance of the restriction provided by the supports. This revealed that the two ankle guards provided no significant support. The two tapes, however, provided significant support before exercise and after 10 minutes but not after 1 hour of exercise. Nonelastic (zinc oxide) tape proved to be the most restrictive at all times measured, especially prior to exercise, when the ankle's range of motion was decreased between 30% and 50%. However, once exercise commenced, the tape stretched, and restriction became less effective.
Article
The identification of a quantifiable dose-response relationship for strength training is important to the prescription of proper training programs. Although much research has been performed examining strength increases with training, taken individually, they provide little insight into the magnitude of strength gains along the continuum of training intensities, frequencies, and volumes. A meta-analysis of 140 studies with a total of 1433 effect sizes (ES) was carried out to identify the dose-response relationship. Studies employing a strength-training intervention and containing data necessary to calculate ES were included in the analysis. ES demonstrated different responses based on the training status of the participants. Training with a mean intensity of 60% of one repetition maximum elicits maximal gains in untrained individuals, whereas 80% is most effective in those who are trained. Untrained participants experience maximal gains by training each muscle group 3 d.wk and trained individuals 2 d.wk. Four sets per muscle group elicited maximal gains in both trained and untrained individuals. The dose-response trends identified in this analysis support the theory of progression in resistance program design and can be useful in the development of training programs designed to optimize the effort to benefit ratio.
Article
The purpose of this study was to quantify the contributions made by individual muscles to support of the whole body during normal gait. A muscle's contribution to support was described by its contribution to the time history of the vertical force exerted by the ground. The analysis was based on a three-dimensional, muscle-actuated model of the body and a dynamic optimization solution for normal walking. The results showed that, in early stance, before the foot was placed flat on the ground, support was provided mainly by the ankle dorsiflexors. After foot-flat, but before contralateral toe-off, support was generated primarily by gluteus maximus, vasti, and posterior gluteus medius/minimus; these muscles were responsible for the first peak seen in the vertical ground-reaction force. The majority of support in midstance was provided by gluteus medius/minimus, with gravity assisting significantly as well. The ankle plantarflexors generated nearly all support in late stance; these muscles were responsible for the second peak in the vertical ground-reaction force. The results showed also that centrifugal forces act to decrease the vertical ground-reaction force, but only by minor amounts, and that resistance of the skeleton to the force of gravity is no larger than 1/2 body weight throughout the gait cycle.
Article
Case report. To describe an alternative treatment approach for patellofemoral pain. Weakness of the hip, pelvis, and trunk musculature has been hypothesized to influence lower-limb alignment and contribute to patellofemoral pain. Two patients who had a chief complaint of patellofemoral pain and demonstrated lack of control of the hip in the frontal and transverse planes during functional movements were treated with an exercise program targeting the hip, pelvis, and trunk musculature. The patients presented in these 2 case reports did not exhibit obvious patellar malalignment or tracking problems; however, on qualitative assessment, both demonstrated excessive hip adduction, internal rotation, and knee valgus during gait and while performing a step-down maneuver. In addition, both patients exhibited weakness of the hip abductors, extensors, and external rotators, as demonstrated by hand-held dynamometry testing. Treatment in both cases occurred over a 14-week period and focused on recruitment and endurance training of the hip, pelvis, and trunk musculature. Functional status, pain, muscle force production, as well as subjective and objective assessment of lower-extremity kinematics during gait and a step-down maneuver were assessed preintervention and postintervention. Both patients experienced a significant reduction in patellofemoral pain, improved lower-extremity kinematics during dynamic testing, and were able to return to their original levels of function. Gluteus medius force production improved by 50% in patient A and 90% in patient B, while gluteus maximus force production improved 55% in patient A and 110% in patient B. Objective kinematic improvements in the step-down task also were demonstrated in patient A. Assessment and treatment of the hip, pelvis, and trunk musculature should be considered in the rehabilitation of patients who present with patellofemoral pain and demonstrate abnormal lower-extremity kinematics.
Article
To determine if timed balance scores on the modified Clinical Test of Sensory Interaction and Balance (CTSIB) were affected by shoe wear in patients with balance and vestibular disorders and to determine if there is a difference in correlation with the Sensory Organization Test (SOT) or in the sensitivity or specificity based on footwear. Prospective correlational trial. Outpatient clinic. Thirty persons (mean age, 63+/-17 y) currently undergoing vestibular physical therapy (PT). All subjects completed the modified CTSIB with their shoes on and off at the end of a PT session; 16 of them (53%) also completed the SOT on the same day. Scores on the modified CTSIB and SOT. No difference existed between scores on the modified CTSIB with shoes on versus off. Similar correlation was found between the modified CTSIB performed with the shoes on and off and SOT scores. The sensitivity and specificity of the modified CTSIB was similar with shoes on and off. The modified CTSIB can be performed with or without shoes, with no difference expected in patient score or test sensitivity or specificity.
Article
Based on the recent suggestion that proximal hip control may be related to a predisposition to anterior cruciate ligament injury, our purpose was to identify gender differences in hip mechanics between female athletes who previously demonstrated greater knee valgus moments and their male counterparts. Descriptive laboratory study. Testing was conducted in a biomechanics research laboratory. Thirty collegiate soccer players (15 women and 15 men) participated in this study. All subjects were healthy with no current complaints of lower extremity injury. Three-dimensional hip joint kinematics and kinetics were collected while subjects performed a side-step cutting maneuver. Gender differences in hip mechanics were compared using independent sample t tests. Compared with male athletes, female athletes demonstrated significantly greater hip internal rotation and decreased hip flexion. In addition, female athletes demonstrated significantly greater hip adductor moments as well as decreased hip extensor moments. Overall, it appeared that female athletes moved into greater hip internal rotation and used less sagittal plane hip motion during the early deceleration phase of the cutting maneuver. The findings of this investigation support the premise that altered hip kinematics and kinetics may influence loading at the knee. Future studies are needed to further explore the impact of these differences on knee loading and to ascertain the underlying causes.
Article
A comparison of electromyographic (EMG) activity of muscles between and within subjects, and during separate occasions of testing, requires normalization. The most common way for generating the reference level used for normalizing shoulder EMG data is with a maximum isometric voluntary contraction (MVIC). The purpose of this study was to develop a parsimonious set of standardized tests that generate an MVIC in all the major muscle groups of the shoulder. Twelve muscles of the dominant shoulder of 15 subjects were examined using a combination of surface and intramuscular electrodes during 15 tests. The results indicated that many tests maximally activated more than one muscle simultaneously. Four tests were identified as being sufficient for generating an MVIC in the 12 muscles examined and are recommended as the standard set for normalizing shoulder muscle EMG: abduction 90 degrees with internal rotation ("empty can"), internal rotation in 90 degrees abduction ("internal rotation 90 degrees"), flexion at 125 degrees with scapula resistance ("flexion 125 degrees"), and horizontal adduction at 90 degrees flexion ("palm press"). The use of these shoulder normalization tests will make comparisons between shoulder EMG studies more reliable.