Novel Insights Into the Intratendinous Pressure Behavior of the Achilles Tendon in Athletes.

BACKGROUND: In contrast to other musculoskeletal tissues, the normal pressure behavior of the Achilles tendon is poorly understood. This study aimed to explore the normal intratendinous and perfusion pressures of the Achilles tendon at rest and during exercise, and investigate potential correlations with tendon load and morphology. HYPOTHESIS: Intratendinous and perfusion pressures of the Achilles tendon exhibit similarities to other musculoskeletal tissues and depend on tendon load and morphology. STUDY DESIGN: Observational study. LEVEL OF EVIDENCE: Level 3. METHODS: A total of 22 recreational athletes were enrolled. Demographics, activity level, and blood pressures were recorded. Achilles tendon thickness and echogenicity were assessed 25 mm proximal to the posterosuperior calcaneal border. In this region, intratendinous and perfusion pressures of the Achilles tendon were measured at rest and during isometric plantarflexion up to 50 N, using the microcapillary infusion technique. Linear mixed models were used to investigate the effects of plantarflexion force, tendon thickness, and echogenicity on intratendinous and perfusion pressures. RESULTS: At rest, intratendinous and perfusion pressures of the Achilles tendon were 43.8 ± 15.2 and 48.7 ± 18.4 mmHg, respectively. Intratendinous pressure increased linearly with plantarflexion force, reaching 101.3 ± 25.5 mmHg at 50 N (P < 0.01). Perfusion pressure showed an inverse relationship, dropping below 0 mmHg at 50 N (P < 0.01). Neither intratendinous nor perfusion pressures of the Achilles tendon correlated with tendon thickness or echogenicity. CONCLUSION: The normal intratendinous resting pressure of the Achilles tendon is higher than other musculoskeletal tissues, making it more susceptible to ischemia. During exercise, intratendinous pressure increases significantly to a level that lowers perfusion pressure, thereby compromising blood supply at already low plantarflexion forces. CLINICAL RELEVANCE: Given the potential role of ischemia in Achilles tendinopathy, our findings caution against intratendinous injections, as they may exacerbate high intratendinous resting pressure, and against prolonged postexercise tendon stretching, as the associated rise in intratendinous pressure may impair the required hyperemic response.

Three-Dimensional Upper Limb Movement Analysis in Children and Adolescents With Brachial Plexus Birth Injury: A Systematic Review.

BACKGROUND: To synthesize the current evidence on clinical use of three-dimensional upper limb movement analysis (3D-ULMA) in children and adolescents with brachial plexus birth injury (BPBI). METHODS: MEDLINE, Embase, and Web of Science were searched for relevant studies up to April 2022. An automatic e-mail alert was installed to ensure no eligible article was missed. Articles evaluating 3D-ULMA in children and adolescents with BPBI were included. Covidence web-based platform was used for blind screening of eligible articles. Twenty-one observational studies with a final sample size of 609, encompassing 493 BPBI cases, met the inclusion criteria. Data were extracted using a custom form to support standardized extraction conforming to the Cochrane Checklist of items. Risk of bias was assessed using the Newcastle-Ottawa Scale, the Strengthening the Reporting of Observational Studies in Epidemiology checklist, and a specifically established quality assessment form for kinematic analysis studies. RESULTS: Study setups differed, including six different types of kinematic devices. Twelve studies used the (modified) Mallet positions for their 3D-ULMA. Throughout the studies, 3D-ULMA was used for various purposes. The Newcastle-Ottawa Scale scored 16 articles with five stars or more, indicating fair to moderate quality. CONCLUSIONS: This systematic review summarizes the different 3D-ULMA kinematic devices, test protocols, and their clinical use for BPBI. The use of 3D-ULMA provides valuable, objective, and quantified data to clinicians with regard to movement strategies; it complements existing clinical scales and can be implemented to evaluate effectiveness of therapy interventions. Implications for future research and clinical practice are discussed.

External to internal glenohumeral strength ratio in non-traumatic rotator cuff pathologies.

Background and study aims: A correct agonist -antagonist strength relationship for shoulder external and internal rotation is necessary for functional stability of the shoulder. This strength relationship is described by the ratio of external to internal strength (ER/IR).The aim of this stydy is to produce comparative data as regards the ER/IR ratio in subjects with different non-traumatic rotator cuff diseases. Design and setting: A cross-sectional study in an outpatient clinic in a tertiary care university hospital. Methods: In 55 subjects with rotator cuff disease (confirmed by physical examination and assessed by ultrasound and magnetic resonance arthrography), the ER/IR ratio of the shoulder was isometrically measured with a hand-held dynamometer and compared with values pertaining to the unaffected shoulder of the same individuals. Results: The mean ER/IR values in the overall group were 0.89 (SD 0.18) and 0.94 (SD 0.22) for the affected and unaffected shoulders, respectively. The ratio was 0.87 (SD 0.23) in patients with subdeltoid bursitis, 0.88 (SD 0.16) in rotator cuff tendinopathy and 0.87 (SD 0.22) in patients with rotator cuff tears. Conclusions: The ER/IR ratio appears to be similar between the affected and unaffected shoulders of subjects with nontraumatic cuff pathologies.

Intratendinous pressure of the Achilles tendon during exercise is related to the degree of tendon torsion.

Torsion of the Achilles tendon (AT) enhances tensile strength, but a high degree of torsion might also be a risk factor for Achilles tendinopathy, due to greater internal compression exerted during tensile loading. However, evidence supporting the grounds for this assumption is lacking. Hence, we aimed to investigate the impact of AT torsion type on intratendinous pressure. Eighteen human fresh frozen cadaveric legs were mounted in a testing rig and a miniature pressure catheter was placed through ultrasound-guided insertion in the midportion region of the AT. Intratendinous pressure was measured during a simulated straight-knee calf stretch and eccentric heel drop. The AT was then carefully dissected and classified into Type I (least), Type II (moderate), and Type III (extreme) torsion. Of the ATs examined, nine were found to have Type I torsion (50%), nine Type II (50%), and none Type III. It was found that the intratendinous pressure of the AT increased exponentially with ankle dorsiflexion during both exercises (p < 0.001) and that this increase was greater in ATs with Type II torsion than Type I torsion (p < 0.05). This study provides the first biomechanical data to support the hypothesis that in athletes with a high degree of torsion in the AT, the midportion area will experience more internal compression during exercise, for example, calf stretching and eccentric heel drops. Whether this phenomenon is also associated with an elevated risk for Achilles tendinopathy needs further prospective investigation.

Intratendinous pressure changes in the Achilles tendon during stretching and eccentric loading: Implications for Achilles tendinopathy.

Mechanical overload is considered the main cause of Achilles tendinopathy. In addition to tensile loads, it is believed that the Achilles tendon may also be exposed to compressive loads. However, data on intratendinous pressures are lacking, and consequently, their role in the pathophysiology of tendinopathy is still under debate. Therefore, we aimed to evaluate the intratendinous pressure changes in the Achilles tendon during stretching and eccentric loading. Twelve pairs of human cadaveric legs were mounted in a testing rig, and a miniature pressure catheter was placed through ultrasound-guided insertion in four different regions of the Achilles tendon: the insertion (superficial and deep layers), mid-portion, and proximal portion. Intratendinous pressure was measured during three simulated loading conditions: a bent-knee calf stretch, a straight-knee calf stretch, and an eccentric heel-drop. It was found that the intratendinous pressure increased exponentially in both the insertion and mid-portion regions of the Achilles tendon during each loading condition (p < 0.001). The highest pressures were consistently found in the deep insertion region (p < 0.001) and during the eccentric heel-drop (p < 0.001). Pressures in the mid-portion were also significantly higher than in the proximal portion (p < 0.001). These observations offer novel insights and support a role for compression in the pathophysiology of Achilles tendinopathy by demonstrating high intratendinous pressures at regions where Achilles tendinopathy typically occurs. To what extent managing intratendinous pressure might be successful in patients with Achilles tendinopathy by, for example, avoiding excessive stretching, modifying exercise therapy, and offering heel lifts requires further investigation.

Exploring the role of intratendinous pressure in the pathogenesis of tendon pathology: a narrative review and conceptual framework.

Despite the high prevalence of tendon pathology in athletes, the underlying pathogenesis is still poorly understood. Various aetiological theories have been presented and rejected in the past, but the tendon cell response model still holds true. This model describes how the tendon cell is the key regulator of the extracellular matrix and how pathology is induced by a failed adaptation to a disturbance of tissue homeostasis. Such failure has been attributed to various kinds of stressors (eg, mechanical, thermal and ischaemic), but crucial elements seem to be missing to fully understand the pathogenesis. Importantly, a disturbance of tissue pressure homeostasis has not yet been considered a possible factor, despite it being associated with numerous pathologies. Therefore, we conducted an extensive narrative literature review on the possible role of intratendinous pressure in the pathogenesis of tendon pathology. This review explores the current understanding of pressure dynamics and the role of tissue pressure in the pathogenesis of other disorders with structural similarities to tendons. By bridging these insights with known structural changes that occur in tendon pathology, a conceptual model was constituted. This model provides an overview of the possible mechanism of how an increase in intratendinous pressure might be involved in the development and progression of tendon pathology and contribute to tendon pain. In addition, some therapies that could reduce intratendinous pressure and accelerate tendon healing are proposed. Further experimental research is encouraged to investigate our hypotheses and to initiate debate on the relevance of intratendinous pressure in tendon pathology.

ULTRASONOGRAPHIC PRESENTATION OF NODULAR CYSTIC FAT NECROSIS AFTER A LOW-VELOCITY TRAUMA: A CASE REPORT.

Objective: Morel-Lavallée lesion is a well-known entity after a high-energy, shearing trauma. Another form of lesion in the subcutaneous tissue is fat necrosis, presenting as a palpable mass. The most common presentation of fat necrosis is oil cysts, which occur mainly in the breast. However, in the lower extremities fat necrosis appears as nodular cystic fat necrosis. We report here a case of a patient with multiple injuries after a low-velocity trauma, who developed fat necrosis. Results: Six months after the traumatic event the patient reported multiple subcutaneous lumps on the right knee. On ultrasonography, the probable diagnosis of post-traumatic fat necrosis with consequent development of nodular cystic fat necrosis was seen. The diagnosis was confirmed based on magnetic resonance imaging (MRI). Discussion: Fat necrosis should be included in the differential diagnosis in cases of tissue injuries after a trauma. Fat necrosis can present months or years after the initial injury. It is a benign entity and is the result of an organized haemorrhage, swelling and oedema that progresses with fibrosis. There is no absolute need for surgical treatment.

A demographic study of acute injuries in basketball players.

Studies that analyse the epidemiology of acute injuries in basketball players in European countries are limited. The purpose is to present an overview of the incidence of injuries and injury patterns in Flanders and to correlate them to possible intrinsic and extrinsic risk factors. All acute injuries that occurred in Flanders during 2009-2013, collected by the insurance, were analysed. The incidence and parameters such as date of birth, date of occurrence of the injury, gender and diagnosis were evaluated. Injury incidence varied from 7.40% up to 8.45%. Females and players at age 16-17, 14-15 and older than 30 are at higher risk. The ankle/foot region is most frequently injured. There is a higher risk of injury after season-and Christmas break. Age, gender and chronometry are risk factors to get injured. Sprains are the most frequent, while the nkle/foot region is the most susceptible to injury. Studies that analyse the epidemiology of acute injuries in basketball players in European countries are limited. Female players and players at age 16-17, 14-15 and older than 30 are at higher risk to basketball injuries. The ankle/foot region is most frequently injured followed by lower arm and hand. There is a higher risk of injury after season-and Christmas break.

Impaired Core Stability as a Risk Factor for the Development of Lower Extremity Overuse Injuries: A Prospective Cohort Study.

BACKGROUND: Core stability has been suggested to influence lower extremity functioning and might contribute to the development of lower extremity overuse injuries. However, prospective studies to investigate this relationship are limited. PURPOSE: To research the role of different components of core stability as risk factors for the development of lower extremity overuse injuries. STUDY DESIGN: Cohort study; Level of evidence, 2. METHODS: A total of 142 first-year physical education students participated in this study. They were tested in 2015 and were prospectively followed for 1.5 years by means of a multilevel injury registration method. Three participants were excluded owing to physical complaints during testing. As such, 139 participants were included in the statistical analysis. At baseline, dynamic postural control, isometric core and hip muscle strength, core muscle endurance, core neuromuscular control and proprioception, and functional movement were measured for all participants. Competing risk regression analyses were performed to identify significant contributors to the development of lower extremity overuse injuries. RESULTS: During the follow-up period, 34 (24%) of the 139 participants developed a lower extremity overuse injury. Significant predictive effects for an overuse injury were found for an increased side-by-side difference in dynamic postural control ( P = .038), decreased isometric hip extension:flexion strength ratio ( P = .046), and decreased abdominal core muscle endurance ( P = .032). CONCLUSION: This study identified measures for dynamic postural control, core muscle strength, and core muscle endurance as significant risk factors for the development of overuse injuries after statistical model building. However, core neuromuscular control and proprioception and functional movement might not allow clinicians to identify patients at risk. These accessible, reliable screening tools could be used in clinical practice with regard to screening and injury prevention for overuse injuries. Injury prediction based on this model needs to be done with caution given the low relative predictive accuracy (53%).

The Role of the Vascular and Structural Response to Activity in the Development of Achilles Tendinopathy: A Prospective Study.

BACKGROUND: Several risk factors have been suggested in the development of Achilles tendinopathy, but large-scale prospective studies are limited. PURPOSE: To investigate the role of the vascular response to activity of the Achilles tendon, tendon thickness, ultrasound tissue characterization (UTC) of tendon structure, and foot posture as possible risk factors in the development of Achilles tendinopathy. STUDY DESIGN: Cohort study; Level of evidence, 2. METHODS: The study began with 351 first-year students at Ghent University. After 51 students were excluded, 300 were tested in the academic years 2013-2014 and 2014-2015 and were followed prospectively for 2 consecutive years by use of a multilevel registration method. Of those, 250 students were included in the statistical analysis. At baseline, foot posture index and UTC were investigated bilaterally. Blood flow and tendon thickness were measured before and after a running activity. Cox regression analyses were performed to identify significant contributors to the development of Achilles tendinopathy. RESULTS: During the 2-year follow-up, 27 of the included 250 participants developed Achilles tendinopathy (11%). Significant predictive effects were found for female sex and blood flow response after running ( P = .022 and P = .019, respectively). The risk of developing Achilles tendinopathy increased if the blood flow increase after running was reduced, regardless of sex, foot pronation, and timing of flow measurements. The model had a predictive accuracy of 81.5% regarding the development of Achilles tendinopathy, with a specificity of 85.0% and a sensitivity of 50.0%. CONCLUSION: This prospective study identified both female sex and the diminished blood flow response after running as significant risk factors for the development of Achilles tendinopathy. UTC of tendon structure, Achilles tendon thickness, and foot posture did not significantly contribute to the prediction of Achilles tendinopathy. A general evaluation of tendon structure by UTC, measurement of tendon thickness, or determination of the foot posture index will not allow clinicians to identify patients at risk for developing Achilles tendinopathy. Furthermore, it may be possible to improve blood flow after activity by using noninvasive techniques (such as prostaglandins, compression stockings, heat, massage, and vibration techniques). These techniques may be useful in the prevention and management of Achilles tendinopathy, but further research is needed.

Chronic fatigue syndrome - an update.

BACKGROUND: Chronic fatigue syndrome is a widespread condition with a huge impact not only on a patient's life, but also on society as evidenced by substantial losses of productivity, informal costs, and medical expenses. The high prevalence rates (0.2-6.4%) and the low employment rates (27-41%) are responsible for the enormous burden imposed on society, with loss of productivity representing the highest cost. The objective of this review is to systematically review the recent literature on chronic fatigue syndrome/myalgic encephalomyelitis. METHODS: The published literature between 1 January 1990 and 1 April 2015 was searched using the MEDLINE, Cochrane Library, and Web of Sciences databases. The reference lists of the selected articles were screened for other relevant articles. RESULTS AND CONCLUSIONS: Despite extensive research, none of the proposed etiological factors have shown strong, reproducible scientific evidence. Over the years, the biopsychosocial model integrating many of the proposed hypotheses has been gaining popularity over the biomedical model, where the focus is on one physical cause. Since the etiological mechanism underlying chronic fatigue syndrome is currently unknown, disease-specific treatments do not exist. Various treatments have been investigated but only cognitive behavior therapy (CBT) and graded exercise therapy (GET) have shown moderate effectiveness.

Incidence and aetiology of acute injuries during competitive road cycling.

INTRODUCTION: Despite the ever-increasing popularity of bicycle racing, the high perceived risk of acute injuries and the recent media attention, studies of acute injuries in road cyclists are rather scarce. The goal of this study is to evaluate the incidence, aetiology and patterns of acute injuries in non-professional competitive road cyclists during cycling races in Flanders. MATERIAL AND METHODS: All acute injuries that occurred during competition in Flanders in 2002 and 2012, collected in the injury registry, were analysed. The incidence, injury rate, diagnosis, circumstances and level of performance were evaluated. RESULTS: A total of 777 documented reports of accidents (1230 injuries) were retrieved for the years 2002 and 2012. There was no significant difference between incidence and injury rate between 2002 and 2012. There was a strong significant difference in the incidence between the different levels of performance in both seasons. Severe injuries were seen in 29.5% in 2002 and in 30.1% in 2012. The most common location of a severe injury was the hand. Collision with another rider was the most common cause of injury. CONCLUSIONS: Almost 1 out of 6 non-professional competitive road cyclists had an accident during cycling races in 2002 and 2012 in Flanders and collision with other riders was the most important cause of a crash. The most common lesion was abrasion, but almost one out of three riders had a severe injury.

Associations between poor oral health and reinjuries in male elite soccer players: a cross-sectional self-report study.

BACKGROUND: Although it is well known that oral pathogens can enter the systemic circulation and cause disease, it is largely unknown if poor oral health increases the risk of sports injuries. The purpose of this study is to investigate the association between poor oral health and reinjuries in male elite soccer players, adjusted for psychosocial problems and player characteristics. METHODS: 184 Players in premier league soccer clubs and 31 elite, junior soccer players in the Netherlands, Belgium and England, were enrolled in a retrospective cross-sectional study. The Sports Injury Risk Indicator, a self assessed questionnaire, was used to obtain information on reinjuries, age and player position, oral health and psychosocial problems. The number of different types of oral health problems was used as an indicator of poor oral health. (SumDental, range 0-2: 0 = no oral health problems, 1 = one type of oral health problem and 2 = two or more types of oral health problems). Multivariable logistic regression was used to investigate whether SumDental was associated with reinjuries, after adjustment for psychosocial problems and player characteristics. RESULTS: 37% of the players reported no oral health problems, 43% reported one type of oral health problem and 20% reported two or more types of oral health problems. After full adjustment for age, player position and psychosocial problems (i.e. injury anxiety, psychophysical stress, unhealthy eating habits and dissatisfaction with trainer/team), poor oral health (SumDental) was positively associated with all kind of reinjuries whether analyzed as a continuous variable or as a categorical variable. The fully adjusted odds ratios for SumDental analyzed as a continuous variable were: in relation to repeated exercise-associated muscle cramps: 1.82 (95% confidence interval (CI): 1.07, 3.12), in relation to muscle or tendon reinjury 1.57 (95% CI: 1.01, 2.45) and in relation to multiple types of reinjury 1.88 (95% CI: 1.19, 2.97). CONCLUSION: The results from this study justify a thorough examination of the effects of oral health problems on the injury risk of playing elite soccer.

A multi-center, double-blind, randomized, placebo-controlled trial protocol to assess Traumeel injection vs dexamethasone injection in rotator cuff syndrome: the TRAumeel in ROtator cuff syndrome (TRARO) study protocol.

BACKGROUND: Shoulder pain is a common musculoskeletal symptom with a wide range of potential causes; however, the majority of conditions can be managed with conservative treatment. The aim of this study is to assess the efficacy and safety of Traumeel injections versus corticosteroid injections and placebo in the treatment of rotator cuff syndrome and bursitis and expand the current evidence base for the conservative treatment of rotator cuff syndrome. METHODS/DESIGN: This is a multi-center, randomized, double-blind, 16-week, three-arm, parallel-group, active- and placebo-controlled trial to assess the efficacy and safety of Traumeel 2 ml injection versus dexamethasone 8 mg injection versus placebo (saline solution). Patients will be randomly allocated to Traumeel, dexamethasone or placebo in a 2:2:1 randomization. After 1 week screening, patients will receive 3 injections at weekly intervals (days 1, 8 and 15) with additional follow-up assessments on day 22, a telephone consultation in week 9 and a final visit at week 15. Male and female patients aged 40 to 65 years, inclusive, will be recruited if they have acute episodes of chronic rotator cuff syndrome and/or bursitis. Patients with calcifications in the shoulder joint or a complete rotator cuff tear will be excluded. At least 160 patients will be recruited. All subacromial injections will be performed under ultrasound guidance utilizing a common technique. The only rescue medication permitted will be paracetamol (acetaminophen), with usage recorded. The primary endpoint is change from baseline in abduction-rotation pain visual analog scale (0-100 mm scale, 0 corresponds to no pain and 100 to extreme pain) at day 22 (Traumeel injections versus dexamethasone injections) for active external rotation. Secondary efficacy parameters include range of motion, disability of arm, shoulder, hand score and patient's/investigator's global assessment. Clinical efficacy will be assessed as non-inferiority of Traumeel with respect to dexamethasone regarding the primary efficacy parameter. DISCUSSION: It is hoped that the results of this trial will expand the treatment options and evidence base available for the management of rotator cuff disease. TRIAL REGISTRATION: ClinicalTrials.gov: NCT01702233 . EudraCT number: 2012-003393-12.

Vibration perception threshold in relation to postural control and fall risk assessment in elderly.

PURPOSE: This study investigates (i) the potential discriminative role of a clinical measure of peripheral neuropathy (PN) in assessing postural performance and fall risk and (ii) whether the integration of a simple screening vibration perception threshold (VPT) for PN in any physical (fall risk) assessment among elderly should be recommended, even if they do not suffer from DM. METHOD: One hundred and ninety-five elderly were entered in a four-group model: DM with PN (D+; n = 75), DM without PN (D-; n = 28), non-diabetic elderly with idiopathic PN (C+; n = 31) and non-diabetic elderly without PN (C-; n = 61). Posturographic sway parameters were captured during different static balance conditions (AMTI AccuGait, Watertown, MA). VPT, fall data, Mini-Mental State Examination and Clock Drawing Test were registered. Two-factor repeated-measures ANOVA was used to compare between groups and across balance conditions. RESULTS: The groups with PN demonstrated a strikingly comparable, though bigger sway, and a higher prospective fall incidence than their peers without PN. CONCLUSIONS: The indication of PN, irrespective of its cause, interferes with postural control and fall incidence. The integration of a simple screening for PN (like bio-thesiometry) in any fall risk assessment among elderly is highly recommended. Implications for Rehabilitation The indication of peripheral neuropathy (PN), irrespective of its cause, interferes with postural control and fall incidence. Therefore, the integration of a simple screening for PN (like bio-thesiometry) in any fall risk assessment among elderly is highly recommended. It might be useful to integrate somatosensory stimulation in rehabilitation programs designed for fall prevention.

Range of motion in femoroacetabular impingement.

Recent epidemiological studies have demonstrated that radiographic features specific to femoroacetabular impingement appear far more frequently in healthy and asymptomatic cohorts than previously anticipated. It remains unclear how incidental findings should be interpreted clinically. In addition, several authors have suggested that a decreased range of motion is part of the clinical presentation of femoroacetabular impingement. The purpose of the present study was to describe and analyze differences in range of motion between femoroacetabular impingement patients, asymptomatic individuals with incidental radiographic findings and healthy controls, using a validated electromagnetic tracking system. Furthermore, it was evaluated which motions were clinically relevant and could be used to differentiate between these three groups. We found all evaluated motions to differ significantly between patients and controls. The anterior impingement test showed a significant difference between patients and asymptomatic cases. In conclusion, functional evaluation of the range of motion appeared in this study as a useful tool in the diagnostic work-up of femoracetabular impingement.

Physical fitness of elite Belgian soccer players by player position.

The purpose of this study was to gain an insight into the physical and physiological profile of elite Belgian soccer players with specific regard to the player's position on the field. The sample consisted of 289 adult players from 6 different first division teams. The players were divided into 5 subgroups (goalkeepers, center backs, full backs, midfielders, and strikers) according to their self-reported best position on the field. The subjects performed anaerobic (10-m sprint, 5 × 10-m shuttle run [SR], squat jump [SJ], and countermovement jump [CMJ]) and aerobic (incremental running protocol) laboratory tests. The strikers had significantly shorter sprinting times (5-, 5- to 10-m time, and SR) compared with the midfielders, center backs, and goalkeepers, whereas the full backs were also significantly faster compared with the goalkeepers and the center backs. The goalkeepers and the center backs displayed higher jumping heights (total mean SJ = 40.7 ± 4.6 cm and CMJ = 43.1 ± 4.9 cm) compared with the other 3 positions, whereas the strikers also jumped higher than the full backs and the midfielders did. Regarding the aerobic performance, both full backs and the midfielders (61.2 ± 2.7 and 60.4 ± 2.8 ml · min(-1) · kg(-1), respectively) had a higher VO2max compared with the strikers, center backs, and goalkeepers (56.8 ± 3.1, 55.6 ± 3.5, and 52.1 ± 5.0 ml · min(-1) · kg(-1), respectively). From this study, it could be concluded that players in different positions have different physiological characteristics. The results of this study might provide useful insights for individualized conditional training programs for soccer players. Aside from the predominant technical and tactical skills, a physical profile that is well adjusted to the position on the field might enhance game performance.

Vastus medialis obliquus atrophy: does it exist in patellofemoral pain syndrome?

BACKGROUND: Quadriceps atrophy and in particular atrophy of the vastus medialis obliquus (VMO) muscle have been frequently related with patellofemoral pain syndrome (PFPS), despite very little objective evidence. HYPOTHESIS: Patients with PFPS exhibit atrophy of the VMO in comparison with healthy controls. STUDY DESIGN: Case-control study; Level of evidence, 3. METHODS: Forty-six patients with PFPS and 30 healthy control persons with similar age, gender, body mass index, and activity index distributions underwent magnetic resonance imaging (MRI) of the quadriceps. The muscle size was determined by calculating the cross-sectional area of the total quadriceps and its components. RESULTS: The cross-sectional area (CSA) of the VMO was significantly smaller in the PFPS group than in the control group (16.67 ± 4.97 cm(2) vs 18.36 ± 5.25 cm(2)) (P = .040). A tendency was noted for a smaller total quadriceps CSA for the PFPS patients at midthigh level (66.99 ± 15.06 cm(2) vs 70.83 ± 15.30 cm(2)) (P = .074). CONCLUSION: This is the first study to examine VMO size in PFPS patients by MRI. Patients with patellofemoral problems exhibited atrophy of the VMO. Although it is not clear whether this atrophy is a result or a cause of PFPS, the results of this study do show that atrophy of the VMO is a contributing factor in PFPS. Longitudinal, prospective studies are needed to establish the cause-effect relation of VMO atrophy and PFPS.

Effect of whole body vibration on intracompartmental pressure in the lower leg.

BACKGROUND: Whole body vibration has important effects on neuromuscular functions. It seems to be a promising tool in the conservative treatment and rehabilitation of compartment syndrome. In the present study we investigated the effect of whole body vibration on intracompartmental pressure in the lower leg during a strenuous static exercise program. METHODS: We conducted a cross-over pilot study in which fifteen healthy male subjects participated. They twice performed a 20.5-min static exercise program on the Fitvibe Medical whole body vibration device, once with 27 Hz vibrations and once without. The intracompartmental pressure was measured by two examiners at the superficial posterior compartment of the left and right lower leg, at rest and during the exercise programs. RESULTS: A general linear model for repeated measures showed a significant difference between the exercise program with vibrations and that without (P = 0.001) and a significant difference in intracompartmental pressure for the factor time of measurement (P < 0.001). Mean intracompartmental pressure was at any point in time lower in the vibrating than in the non-vibrating exercise conditions, though not always significant. In the program with vibrations the exercise pressures showed a non-significant trend to decrease (from 23.5 mmHg to 21.3 mmHg) as the program advanced, while in the non-vibration program, there was a trend to increase (from 24.1 to 27.9 mmHg). CONCLUSIONS: The mean intracompartmental pressure was lower when whole body vibration at 27 Hz was superimposed. Therefore, whole body vibration seems to be a possible tool to lower intracompartmental pressure. Further research is needed to confirm whether these findings are also applicable in patients, athletes, and in dynamic exercises.