Quadriceps Muscle Group Research Articles

Does Roller Massage With a Foam Roll Change Pressure Pain Threshold of the Ipsilateral Lower Extremity Antagonist and Contralateral Muscle Groups? An Exploratory Study.

Foam rolling is a popular intervention used by allied health professionals and the general population. Current research suggests that foam rolling may have an effect on the ipsilateral antagonist muscle group and produce a cross-over effect in the muscles of the contralateral limb. The purpose of this study was to examine the acute effects of foam rolling to the left quadriceps on ipsilateral antagonist hamstrings and contralateral quadriceps muscle group pressure pain threshold (PPT). Through this research, we sought to gather data to further develop the methodology for future studies of this intervention. A pretest-posttest exploratory study. University kinesiology laboratory. 21 healthy adults (age = 27.52 ± 8.9y). Video-guided foam roll intervention on the left quadriceps musculature. Ipsilateral hamstring (antagonist) and contralateral quadriceps muscle PPT. A significant difference was found between pretest to posttest measures for the ipsilateral hamstrings (t[20] = -6.2, P < 0.001) and contralateral quadriceps (t[20] = -9.1, P < 0.001) suggesting an increase in PPT. These findings suggest that foam rolling of the quadriceps musculature may have an acute effect on the PPT of the ipsilateral hamstrings and contralateral quadriceps muscles. Clinicians should consider these results to be exploratory and future investigations examining this intervention on PPT is warranted.

The interaction between the vastus medialis and vastus intermedius and its influence on the extensor apparatus of the knee joint.

Although the vastus medialis (VM) is closely associated with the vastus intermedius (VI), there is a lack of data regarding their functional relationship. The purpose of this study was to investigate the anatomical interaction between the VM and VI with regard to their origins, insertions, innervation and function within the extensor apparatus of the knee joint. Eighteen human cadaveric lower limbs were investigated using macro-dissection techniques. Six limbs were cut transversely in the middle third of the thigh. The mode of origin, insertion and nerve supply of the extensor apparatus of the knee joint were studied. The architecture of the VM and VI was examined in detail, as was their anatomical interaction and connective tissue linkage to the adjacent anatomical structures. The VM originated medially from a broad hammock-like structure. The attachment site of the VM always spanned over a long distance between: (1) patella, (2) rectus femoris tendon and (3) aponeurosis of the VI, with the insertion into the VI being the largest. VM units were inserted twice-once on the anterior and once on the posterior side of the VI. The VI consists of a complex multi-layered structure. The layers of the medial VI aponeurosis fused with the aponeuroses of the tensor vastus intermedius and vastus lateralis. Together, they form the two-layered intermediate layer of the quadriceps tendon. The VM and medial parts of the VI were innervated by the same medial division of the femoral nerve. The VM consists of multiple muscle units inserting into the entire VI. Together, they build a potential functional muscular complex. Therefore, the VM acts as an indirect extensor of the knee joint regulating and adjusting the length of the extensor apparatus throughout the entire range of motion. It is of clinical importance that, besides the VM, substantial parts of the VI directly contribute to the medial pull on the patella and help to maintain medial tracking of the patella during knee extension. The interaction between the VM and VI, with responsibility for the extension of the knee joint and influence on the patellofemoral function, leads readily to an understanding of common clinical problems found at the knee joint as it attempts to meet contradictory demands for both mobility and stability. Surgery or trauma in the anteromedial aspect of the quadriceps muscle group might alter a delicate interplay between the VM and VI. This would affect the extensor apparatus as a whole.

EMG Asymetricity of Selected Knee Extensor Muscles in Sustained Squat Posture (A Yogic Posture) of Athletes in Relation to their Gender and Performance

Squat is a popular yogic exercise or posture, most frequently used for quadriceps strengthening and rehabilitation. It is used for evaluation process or test by physiotherapists/clinicians/others associated with rehabilitation of athletes to strengthen their lower-body muscles and connective tissues after joint-related injury. It has been used extensively for therapeutic treatment of ligament lesions, patellofemoral dysfunctions, patellar subluxation and patellar dislocation etc. The purpose of this study was to compare the effect of sustained squat posture (a yogic posture) of athletes among male (n1=32) and female (n2=18) with high and low performance (based upon median split method) on EMG activity of Vastus Medialis (VM) and Vastus Lateralis (VL) muscles for 120 seconds. Squatting was performed at an angle of 135o-150o because strength of knee extensor (muscles) varies between these angles and is an important consideration for the performance of numerous physical daily routine activities such as walking, running, cycling, stepping and driving including development of fundamental skills for different sports across all ages and sex. VM and VL from the Quadriceps muscle group were chosen for recording the physiological signal simultaneously from right and left leg of the subjects, as these muscles determines stress on the patellofemoral joint and stabilizes the patellar bone during squatting. Frequency and time domain variables were selected to extract meaningful information from the EMG signal using the algorithm developed in MATLAB. The selected variables were Median Frequency (MDF), Mean Frequency (MNF), Root Mean Square (RMS) and Integrated EMG (IEMG). Statistical analysis showed significant differences among gender and performance level along with significant bilateral asymmetry in these athletes. Understanding from the findings is pivotal for achieving optimal muscular strength, for the development of strength endurance and reducing the prospect of training-related injuries

Relationship between geometry of the extensor mechanism of the knee and risk of anterior cruciate ligament injury.

The complex inter-segmental forces that are developed across an extended knee by body weight and contraction of the quadriceps muscle group transmits an anteriorly directed force on the tibia that strain the anterior cruciate ligament (ACL). We hypothesized that a relationship exists between geometry of the knees extensor mechanism and the risk of sustaining a non-contact ACL injury. Geometry of the extensor mechanism was characterized using MRI scans of the knees of 88 subjects that suffered their first non-contact ACL injury and 88 matched control subjects with normal knees that were on the same team. The orientation of the patellar tendon axis was measured relative to the femoral flexion-extension axis to determine the extensor moment arm (EMA), and relative to tibial long axis to measure coronal patellar tendon angle (CPTA) and sagittal patellar tendon angle (SPTA). Associations between these parameters and ACL injury risk were tested with and without adjustment for flexion and internal rotation position of the tibia relative to the femur during MRI data acquisition. After adjustment for internal rotation position of the tibia relative to the femur there were no associations between EMA, CPTA, and SPTA and risk of suffering an ACL injury. However, increased internal rotation position of the tibia relative to the femur was significantly associated with increased risk of ACL injury in female athletes both in univariate analysis (Odds Ratio = 1.16 per degree of internal rotation of the tibia, p = 0.002), as well as after adjustment for EMA, CPTA, and SPTA.: © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:965-973, 2017.

The Time-Varying Nature of Electromechanical Delay and Muscle Control Effectiveness in Response to Stimulation-Induced Fatigue.

Neuromuscular electrical stimulation (NMES) and Functional Electrical Stimulation (FES) are commonly prescribed rehabilitative therapies. Closed-loop NMES holds the promise to yield more accurate limb control, which could enable new rehabilitative procedures. However, NMES/FES can rapidly fatigue muscle, which limits potential treatments and presents several control challenges. Specifically, the stimulation intensity-force relation changes as the muscle fatigues. Additionally, the delayed response between the application of stimulation and muscle force production, termed electromechanical delay (EMD), may increase with fatigue. This paper quantifies these effects. Specifically, open-loop fatiguing protocols were applied to the quadriceps femoris muscle group of able-bodied individuals under isometric conditions, and the resulting torque was recorded. Short pulse trains were used to measure EMD with a thresholding method while long duration pulse trains were used to induce fatigue, measure EMD with a cross-correlation method, and construct recruitment curves. EMD was found to increase significantly with fatigue, and the control effectiveness (i.e., the linear slope of the recruitment curve) decreased with fatigue. Outcomes of these experiments indicate an opportunity for improved closed-loop NMES/FES control development by considering EMD to be time-varying and by considering the muscle recruitment curve to be a nonlinear, time-varying function of the stimulation input.

New insight in the architecture of the quadriceps tendon.

BackgroundPublished data regarding the structure of the quadriceps tendon are diverse. Dissection of the quadriceps muscle group revealed that beside the rectus femoris, vastus lateralis, vastus intermedius and vastus medialis a fifth muscle component– named the tensor vastus intermedius consistently fused into quadriceps tendon. It can be hypothesized that all these elements of the extensor apparatus of the knee joint must also be represented in the quadriceps tendon. This study investigated the multi-layered quadriceps tendon with special emphasis on all components of the quadriceps muscle group including the newly discovered tensor vastus intermedius.MethodsTen cadaveric lower limbs were dissected. All muscle bellies of the extensor apparatus of the knee joint were identified and traced distally until they merged into the quadriceps tendon. Connections between the different aponeurotic layers of each muscle were studied from origin to insertion. The fusing points of each layer were marked. Their distance to the patella and the distances between the fusing points were measured.ResultsSix elements of the quadriceps muscle group form a tri-laminar structure of the quadriceps tendon. The intermediate layer could be further sub-divided. The elements of the quadriceps tendon are 1. lateral aponeurosis of the vastus intermedius, 2. deep and 3. superficial medial aponeurosis of the vastus intermedius, 4. vastus lateralis, 5. tensor vastus intermedius and 6. rectus femoris. Even with differences in fiber direction – these elements join each other a certain distance proximal to the patella.All elements were fused over a region measuring 13 to 90 mm proximal to the patella. Lateral parts of the vastus intermedius formed the deepest layer of the quadriceps tendon. The superficial and deep layer of the medial vastus intermedius aponeurosis fused 56 mm (range, 30 to 90 mm) and 33 mm (range, 13 to 53 mm) above the patella with the aponeurosis of the tensor vastus intermedius and vastus lateralis respectively. Together they built the two-layered intermediate layer of the quadriceps tendon. The tendon of the rectus femoris forms the superficial layer. The vastus medialis inserts medially in all layers of the quadriceps tendon.Fibers of the lateral muscle components were oriented towards the medial, and fibers of the medial muscle components were oriented towards the lateral femoral condyle.ConclusionsThe three-layered quadriceps tendon is formed by six elements. These are 1. lateral aponeurosis of the vastus intermedius, 2. deep and 3. superficial medial aponeurosis of the vastus intermedius, 4. vastus lateralis, 5. tensor vastus intermedius and 6. rectus femoris. These elements of the extensor apparatus join each other proximal to the patella in a complex onion-like architecture. Its two-layered intermediate layer shows variable fusions points. The vastus medialis contributes to the quadriceps tendon with its medial insertion into all layers of the quadriceps tendon.

Oxygenation and neuromuscular activation of the quadriceps femoris including the vastus intermedius during a fatiguing contraction.

The purpose of this study was to assess oxygenation and neuromuscular activation of the quadriceps femoris muscle group, including the vastus intermedius (VI), during a fatiguing contraction. Eleven healthy men performed an isometric knee extension at 50% of the maximum voluntary contraction until failure. Near-infrared spectroscopy was used to measure tissue oxygen saturation (StO2 ), and surface electromyography was used to quantify the median frequency (MF) of the four individual quadriceps femoris muscles. A significant decrease in StO2 began at 25% of time to exhaustion in all four muscles, and StO2 of the VI was significantly higher than StO2 of the vastus medialis (VM) from 25% of time to exhaustion until 95% of time to exhaustion. The MF of the VI did not significantly decrease during the fatiguing task. We found a significant correlation between ∆MF and ∆StO2 in the VI (r=0·745, P<0·01) and a significant correlation between StO2 and time to exhaustion in the VM and rectus femoris (RF) (VM, r=0·684, P<0·05; RF, r=0·635, P<0·05). These results suggest that muscle O2 saturation in the VI is associated with neuromuscular fatigue during a fatiguing isometric contraction, and the level of oxygenation in the VM and RF is a key to sustaining a fatiguing contraction.

Reviewing morphology of Quadriceps femoris muscle

Abstract Purpose: Quadriceps is composite muscle of four portions rectus femoris, vastus intermedius, vastus medialis and vatus lateralis. It is inserted into patella through common tendon with three layered arrangement rectus femoris superficially, vastus lateralis and vatus medialis in the intermediate layer and vatus intermedius deep to it. Most literatures do not take into account its complex and variable morphology while describing the extensor mechanism of knee, and wide functional role it plays in stability of knee joint. It has been widely studied clinically, mainly individually in foreign context, but little attempt has been made to look into morphology of quadriceps group. The diverse functional aspect of quadriceps group, and the gap in the literature on morphological aspect particularly in our region what prompted us to review detail morphology of this group. Method: Study consisted dissection of 40 lower limbs (20 rights and 20 left) from 20 embalmed cadavers from Department of Anatomy Rural Medical College, PIMS Loni, Ahmednagar (M) India. Results: Rectus femoris was a separate entity in all the cases. Vastus medialis as well as vastus lateralis found to have two parts, as oblique and longus. Quadriceps group had variability in fusion between members of the group. The extent of fusion also varied greatly. The laminar arrangement of Quadriceps group found as bilaminar or trilaminar. The insertion level of vastus medialis and vastus lateralis on patella varied greatly. Vastus lateralis found to extent to whole extent of lateral border of patella. The extension of fibrous band like structure from lower horizontal fibers of vastus medialis to adductor tubercle also noticed in one case. Conclusion: There is wide variability in the quadriceps group of muscles that we came across, then believed. This variability in the quadriceps group might affect the stability of the knee joint but needs, to prove clinically. The inding may also help in the understanding the factors associated with anterior knee pain and its management.

Quadriceps function relates to muscle size following ACL reconstruction.

It remains unclear what role reduced volume and cross-section area (CSA) of individual quadriceps muscles may play in persistent quadriceps weakness and more global dysfunction following ACL reconstruction (ACLR). The purpose of this investigation was to establish the relationship between cross-sectional area of the quadriceps muscle group and measures of knee related and quadriceps function following ACLR. Thirty participants with a history of primary, unilateral ACLR experiencing persistent quadriceps activation failure participated in this cohort study. Clinical factors including International Knee Documentation Committee (IKDC) score, normalized knee extension MVIC torque (Nm/kg) and quadriceps central activation ratio (CAR, %) were assessed in addition to CSA. Quadriceps CSA was measured via magnetic resonance imaging (MRI; Siemens Avanto 1.5T). Quadriceps CSA (cm(2) ) and quadriceps volume (cm(3) ) as well as individual muscle estimates were identified within a 10 cm mid-thigh capture area. Pearson's product-moment correlation coefficients (r) established relationships between CSA and all other variables. Stepwise linear regression established which CSA factors were able to successfully predict clinical factors. Knee extension MVIC torque was strongly correlated with Vastus Intermedius (VI; r = 0.857, p < 0.001) CSA as well as partial VI (r = 0.849, p < 0.001) and quadriceps (r = 0.830, p < 0.001) volume. Partial VI (r = 0.365, p = 0.047) volume was weakly correlated with IKDC score. Knee extension MVIC torque was strongly predicted using VI CSA alone (R(2) = 0.725) or in combination with Vastus Medialis CSA (VM; R(2) = 0.756). Statement of Clinical Significance: Atrophy of the VI and VM muscles negatively impacts knee extension strength following ACLR. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1656-1662, 2016.

Multi-parametric MR imaging of quadriceps musculature in the setting of clinical frailty syndrome.

Frailty is a common geriatric syndrome associated with loss of skeletal muscle mass (sarcopenia) conferring an increased risk of rapid decline in health and function with increased vulnerability to adverse outcomes. The purpose of this study was to investigate the correlation between diffusion tensor, T2 and intramuscular fat content values of the quadriceps muscle group and clinical frailty status using diffusion tensor MR imaging. Subjects were recruited from the Arizona Frailty cohort composed of all females with frailty status based on the Fried criteria, including 6 non-frail and 10 pre-frail/frail adults, as well as a community sample of 11 young, healthy controls. Axial images of both thighs were obtained on a 3-T magnet with T1, T2 and diffusion tensor imaging as well as intramuscular fat analysis. Diffusion tensor and T2 values were determined by region-of-interest measurements at the proximal, mid and distal thirds of both thighs. Data were evaluated to determine differences between measured values and frailty status. The mean fractional anisotropy (FA) values in the bilateral quadriceps muscles demonstrated significant differences (F = 7.558, p = 0.0030) between the control and pre-frail/frail and non-frail and pre-frail/frail groups. There was a significant difference in mean T2 (F = 21.675, p < 0.0001) and lipid content (F = 19.266, p < 0.0001) among all three groups in the total quadriceps muscle group. The quadriceps musculature of pre-frail/frail adults demonstrated increased FA compared to young controls and non-frail adults with increasing T2 and intramuscular fat among the control, non-frail and pre-frail/frail categories.

Knee Pain Associated with Rupture of Tensor Vastus Intermedius, a Newly Discovered Muscle: A Case Report

Introduction: Muscle strains within the quadriceps muscle group are common and occur mostly in the rectus femoris. We report a case of an isolated rupture of the tensor vastus intermedius (TVI); a muscle that has recently been described. It belongs to the quadriceps muscle group and is closely related to the vastus lateralis and vastus intermedius. Case presentation: A healthy 62-year old woman presented with a history of a sudden onset of left knee and thigh pain after stumbling and preventing a near fall. Rupture of the aponeurotic tendon of the TVI was diagnosed by magnetic resonance imaging (MRI). Conservative treatment was successful. Four months after injury the patient returned to her pre-injury level of activity. MRI evaluation five months post-injury revealed full resorption of the muscular haematoma and a healed TVI aponeurosis with scar tissue formation. Conclusion: Due to its anatomic appearance, lesions to the TVI may be overlooked. The isolated rupture of the TVI in the present case further supports the recent finding, that the TVI is a distinct anatomical structure independent of the adjacent vasti.

Effects of ligation of lateral intermuscular septum perforating vessels on blood supply to the femur.

With a subvastus approach to the femur, the vessels that perforate the lateral intermuscular septum (LISP-vessels) must be ligated. The effect on the blood supply to the femur remains unclear. The purpose of the current study was to investigate the effect of ligation of the LISP-Vessels on the blood supply and to examine the anatomy of the LISP-vessels and the anastomoses around the femur. In six human cadavers the LISP vessels were ligated by a lateral subvastus approach on one side. The contralateral side served as control group. After bilateral injection of different coloured silicon dyes into the lateral and medial circumflex femoral artery (green), deep femoral artery (red) and the superficial femoral artery (blue) dissection was performed bilaterally. The arterial perfusion on both sides was compared and the anatomy of the LISP vessels studied. The medullary perfusion of the femur was not altered by the ligation of the LISP vessels. It did also not lead to a decrease in periosteal vessel filling. The LISP vessels were shown to be a part of a complex and rich anastomotic network and play an important role in the perfusion of the femur and quadriceps muscle group. The ligature could be compensated for by this anastomotic network. Branches to the periosteum separate from the LISP vessels immediately after perforating the lateral intermuscular septum. The linea aspera turned out to be an important area for the femoral blood supply. Exposure of the femur through a lateral subvastus approach with ligation of LISP vessels causes a certain degree of soft tissue trauma. However, by using a gentle surgical technique the periostal perfusion of the femur can be preserved by a potent anastomotic network after ligation of the LISP vessels if they are not ligated to close to the lateral intermuscular septum and the linea aspera is not unnecessarily exposed.

Neuromuscular Activation of the Vastus Intermedius Muscle during Isometric Hip Flexion.

Although activity of the rectus femoris (RF) differs from that of the other synergists in quadriceps femoris muscle group during physical activities in humans, it has been suggested that the activation pattern of the vastus intermedius (VI) is similar to that of the RF. The purpose of present study was to examine activation of the VI during isometric hip flexion. Ten healthy men performed isometric hip flexion contractions at 25%, 50%, 75%, and 100% of maximal voluntary contraction at hip joint angles of 90°, 110° and 130°. Surface electromyography (EMG) was used to record activity of the four quadriceps femoris muscles and EMG signals were root mean square processed and normalized to EMG amplitude during an isometric knee extension with maximal voluntary contraction. The normalized EMG was significantly higher for the VI than for the vastus medialis during hip flexion at 100% of maximal voluntary contraction at hip joint angles of 110° and 130° (P < 0.05). The onset of VI activation was 230–240 ms later than the onset of RF activation during hip flexion at each hip joint angle, which was significantly later than during knee extension at 100% of maximal voluntary contraction (P < 0.05). These results suggest that the VI is activated later than the RF during hip flexion. Activity of the VI during hip flexion might contribute to stabilize the knee joint as an antagonist and might help to smooth knee joint motion, such as in the transition from hip flexion to knee extension during walking, running and pedaling.

Desgarros del músculo recto femoral. Actualización en RM

The tear of the anterior rectus femoris is the most frequent injury of the quadriceps muscle group, and one of the most common causes of lower limb muscle lesions (after the injury of the hamstring muscle group). As its anatomy is complex, and symptoms may be unclear, imaging and in particular, Magnetic Resonance Imaging (MRI) provides precise information on the type of tear, topography, extent, and severity.This article presents a detailed description of the anatomy of the RF and a selective study by MRI, with specific technical inputs to optimise this study method. The current concepts of tendinous, myotendinous, and the infrequent myofascial muscle-tendon tears are also presented, with details of key information that must be contemplated in MRI reports of paramount importance to the traumatology doctor.

Effects of prolonged patellar tendon vibration on force steadiness in quadriceps femoris during force-matching task

The quadriceps femoris (QF) muscle group plays an essential role in human movement, such as standing, walking and running. The ability to maintain a steady force during physical activity of the human lower limb is important for mobility, postural control and balance. Although prolonged mechanical vibration of the muscle-tendon unit can moderate the efficacy of synaptic input from Ia afferent onto the α-motor neuron pathway, the effect of prolonged tendon vibration on fluctuations of knee extensor force has received little attention. The purpose of the present study was to examine the effects of prolonged patellar tendon vibration on the force steadiness of the QF muscle. Nine healthy men performed a submaximal force-matching task involving isometric knee extension before and after patellar tendon vibration or quiet seated rest (n = 7, control condition) for 30 min. The target force was 2.5, 10 and 30 % of maximal voluntary contraction (MVC). Surface electromyography (EMG) of the four QF synergists was recorded and normalized to EMG amplitude during the MVC. The knee extension force and the EMG amplitude of vastus medialis during the MVC were significantly reduced after the vibration, but did not significantly decrease in the control condition. Fluctuations of force and normalized EMG of individual QF muscles at each submaximal force level did not significantly change after the vibration. We conclude that prolonged patellar tendon vibration does not influence the force steadiness of the QF muscle during an isometric force-matching task.

Non pharmacological knee osteoarthritis treatment

Osteoarthritis (OA) is a chronic disorder which mostly results with functional impairment and disability. The goal of the treatment program is to decrease pain and disability and to increase functional capacity and quality of life. One of the main parts of the treatment is nonpharmacological treatment modalities. These are weight loss, educational programs in modifying lifestyle and joint protective techniques, assistive devices, physical therapy (superficial and deep heat-cold applications, electrotherapeutic modalities, neuromuscular electrical stimulation), exercise and balneotherapy. Exercise therapy includes both aerobic exercise and strengthening programs. Choosing an appropriate exercise program depends on the patient's clinical evaluation and need. Although quadriceps muscle group is the primary stabilizer of knee joint, hamstring group exercises should also be recommended for a full performance. Progressive resistive exercise programs are found to have beneficial effects in pain and mobility. There are large evidence trials on the positive effects in the symptoms of OA of home-based exercise programs. Most of the studies reported the effectiveness of land-based exercises in knee OA patients. However aquatic exercises are another alternative for knee OA patients as it is safe, enjoyable and has no side effects. One of the widely used treatment option is balneotherapy and spa therapy. It was found to be effective on pain relief, functional capacity and quality of life parameters. Thermal action and chemical minerals play a significant role in its beneficial effect, however there is not an accepted clear concept about its mechanism. There is growing level of evidence about balneotherapy and spa therapy in the management of knee OA and it seems to take part in some of the treatment recommendations.

Preliminary design of a new device to measure muscle function.

A description and early results are presented for a novel device to estimate the torque-angle and torque-angular velocity properties of the quadriceps muscle group using electrical stimulation. The device straps to the shin and is moved by the operator while pulses of stimulation are applied to the motor point of the quadriceps. During stimulation, the operator raises and lowers the leg to the desired angle, and also can oscillate the leg to generate a rich velocity profile. The resulting muscle force is measured by a load cell contained in the device. In a preliminary study using 11 healthy subjects, normalized torque-angle and torque-velocity data for the quadriceps were consistent with literature results that used maximum voluntary contraction methods.

Potential Risks And Distribution Pattern Of Intramuscular Fat In Obese Children

PURPOSE: The purpose of this study was to assess relationship between IMF and physiological and biochemical variables. METHODS: Thirty-seven obese boys and girls participated in this study (age, 10.4 ± 2.1 years; height, 146.2 ± 13.4 cm; weight, 56.1 ± 16.5 kg; percentage of overweight, 41.1 ± 16.8%). This study was conducted a part of treatment of the subjects and was approved by the institutional review board of local committees. Computed tomography (CT) images were taken at the mid-thigh and umbilicus levels. Using the CT images, IMF index of the quadriceps femoris (QF), hamstrings (HM) and adductor (AD) muscle groups based on mean grey scale level of the interested muscle groups and visceral fat cross-sectional area (CSA) were calculated. For the mid-thigh CT image, skeletal muscle CSA and subcutaneous fat was also calculated. Plasma triglyceride, FFA, HDL-cholesterol, total-cholesterol, AST, ALT, glucose and HbA1c were measured from fasting blood drop. RESULTS: IMF index of QF, HM and AD was significantly different in all comparisons: HM was the lowest (1066 ± 6), meaning largest IMF depot, and QF was the highest (1080 ± 3), meaning smallest IMF depot. Stepwise regression analysis revealed that QF CSA, visceral fat CSA, and triglyceride were extracted to predict IMF index in QF (R=0.707, P < 0.01). For IMF index in HM, visceral fat CSA, age, triglyceride, percentage of overweight, and sex were extracted (R=0.806, P < 0.01). Interestingly, percentage of overweight was the only extracted variable to predict IMF index in AD (R=0.529, P < 0.01). CONCLUSIONS: These results suggest that muscle-specific IMF deposition pattern was observed in obese children and that intramuscular fat in each muscle group may have physiological and biochemical specific roles.

The influence of estradiol on muscle damage and leg strength after intense eccentric exercise.

To examine the influence of estradiol on muscle damage and leg strength after intense eccentric exercise. Eight men (MEN), eight normally menstruating women (WomenNM), and eight women using oral contraceptives (WomenOC) participated in this study. Subjects performed 240 maximal-effort bilateral eccentric contractions of the quadriceps muscle groups designed to elicit exercise-induced muscle damage (EiMD). Serum creatine kinase (CK), myoglobin (Mb), and fatty acid-binding protein (FABP) concentrations were measured before (pre-) EiMD, as well as 0, 6, 24, and 48 h post-EiMD. Peak isometric quadriceps torque (i.e., leg strength) was measured pre-EiMD, as well as 24 and 48 h post-EiMD. The increases in CK, Mb, and FABP concentrations from pre- to post-EiMD were greater in MEN (10-fold, 15-fold, and fourfold, respectively) and WomenOC (sevenfold, 11-fold, and ninefold) compared with WomenNM (five-, six-, and threefold; p < 0.05). The decline in leg strength was about 10 % pre- to 24 h post-EiMD in all groups and decreased a further 10-15 % by 48 h post-EiMD in the MEN and WomenOC only. Our findings suggest an important role of estradiol in blunting the muscle damage response to intense eccentric exercise and preserving muscle function after EiMD.

Distal extension of the direct anterior approach to the hip poses risk to neurovascular structures: an anatomical study.

The anterior approach to the hip gained popularity for total hip arthroplasty in recent years. Distal extension of the anterior approach, sometimes needed intraoperatively, potentially endangers neurovascular structures to the quadriceps. The aim of this study was to determine the anatomical structures placed at risk by distal extension of the anterior approach to the hip. Seventeen cadaveric hemipelves from twelve human specimens were dissected. The femoral nerve and its branches and the vessels arising from the lateral femoral circumflex artery were assessed in relation to the distal extension of the anterior approach. The damage caused by the introduction of a cerclage cable passer was also investigated. The area immediately distal to the intertrochanteric line is a common entry point for several nerve branches and is a useful distal landmark for surgeons to use to protect important neurovascular structures. The distal extension of the anterior approach compromises the nerve supply to the anterolateral portions of the quadriceps. Introduction of a cerclage cable passer through the anterior access also jeopardizes nerve branches to the vastus lateralis, lateral parts of the vastus intermedius, and branches of the lateral femoral circumflex artery. Distal extension of the direct anterior approach to the hip is challenging to accomplish without neurovascular injury to anterolateral parts of the quadriceps muscle group. In addition, important neurovascular structures are endangered with the introduction of a cable passer through the anterior approach. Distal extension of the direct anterior approach to the hip beyond the intertrochanteric line may compromise neurovascular structures supplying the quadriceps muscle.