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Comparison of Pedicled Adductor Longus and Pedicled Sartorius Flap in Inguinal Reconstruction, a Fresh Cadaver Study. J Pers Med 2023; 13:jpm13010143. [PMID: 36675804 PMCID: PMC9860770 DOI: 10.3390/jpm13010143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Revised: 01/08/2023] [Accepted: 01/09/2023] [Indexed: 01/13/2023] Open
Abstract
Reconstruction surgeries in the inguinal area are challenging for vascular surgeons, oncologists, orthopedists, and others. The pedicled sartorius flap is the most commonly used flap for reconstruction. The pedicled adductor longus is reported as a new method to reconstruct the inguinal region. The related anatomic study is rare. This work aims to make a comparison of pedicled adductor longus and pedicled sartorius on cadavers for better use. Out of the 12 thighs in the 6 cadavers analyzed, the author compares two surgical methods in terms of surgical details, exposure of vascular and nerve pedicle, flap harvesting, flap transposition and flap volume, etc. Through the course of this study, it is showed that the adductor longus flap had a sizable advantage over the sartorius flap in terms of exposure, harvesting, and flap volume.
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Bilateral accessory head of the adductor longus muscle: an anatomical case study. Folia Morphol (Warsz) 2022; 82:416-421. [PMID: 35187634 DOI: 10.5603/fm.a2022.0015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2021] [Revised: 01/14/2022] [Accepted: 01/17/2022] [Indexed: 11/25/2022]
Abstract
The adductor longus muscle, with its proximal origin at the pubic bone and distal at the linea aspera, is reported to be one of the most frequently injured groin muscles in contact sports, namely football or ice hockey. Notwithstanding, there is a scarcity of published works regarding the accessory heads of the adductor longus muscle in the existing literature, let alone the clinical significance of the said variant. The following study is a case report describing bilateral accessory heads of the adductor longus muscle in a 97-year old female cadaver. A routine cadaveric dissection revealed two accessory heads on the right thigh and one on the left thigh of a donor with no known structural or pathological abnormalities of the proximal lower extremity. The anterior division of the obturator nerve provided nerve supply to the variants on both sides. The deep femoral, superficial external pudendal, femoral vessels were responsible for the vascular supply to the accessory heads of the adductor longus. Undoubtedly, extensive knowledge regarding the variant anatomy of the hip adductor muscles is of immense importance to physiotherapists and orthopaedists treating patients for their injury or complete tears. Nonetheless, there is little information regarding the accessory heads of the adductor longus in the existing literature (originating mostly from cadaveric studies) that requires further evaluation in vivo to assess whether this variant might have an impact on a patient's everyday life.
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The Pedicled Flap of Adductor Longus, a New Technique for Inguinal Reconstruction. Front Surg 2022; 8:639893. [PMID: 34977135 PMCID: PMC8717469 DOI: 10.3389/fsurg.2021.639893] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2021] [Accepted: 11/10/2021] [Indexed: 11/13/2022] Open
Abstract
Introduction: Reconstruction surgeries of the inguinal area pose a challenge for oncological and orthopedic surgeons, especially after radical local resection (RLR), radical inguinal lymph node dissection (RILND), or both. Although numerous surgical procedures have been reported, there is no report about a pedicle adductor longus flap method. The aim of this work is to show our experience about inguinal reconstruction with pedicled adductor longus flap and associated outcomes. Patients and Methods: A retrospective study of 16 patients with localized inguinal region interventions and reconstructed by adductor longus flap from March 2016 to July 2020. Patients' average age was 60.0 years (range = 38-79 years) and had postoperative follow-up of 10 months (ranging 2-19 months). All patients had unilateral inguinal region involvement-seven cases on the left and nine cases on the right. The patients' clinical course, operative course, and postoperative follow-up data were evaluated. Results: All 16 patients recovered well post-operatively and did not require any re-intervention. Four patients experienced negligible discomfort around the groin area. Five patients experienced a minor strength deficit in thigh adduction compared with that of preoperative strength in the same or contralateral leg. The aforementioned complications resolved during the postoperative course and had no functional impact on their activity of daily living. All adductor longus flaps survived, completely filled the inguinal dead space, and wounds healed uneventfully within 3 weeks except for three patients who suffered delayed wound healing for more than 4 weeks. Other common complications such as infection, seroma, or wound dehiscence were not encountered in this series. Conclusion: The adductor longus flap is a reliable alternative method for inguinal region reconstruction following radical local resection (RLR), radical inguinal lymph node dissection (RILND), or both.
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Proximal Adductor Longus Tendon Repair With a Concomitant Distal Fascial Release for Complete Hip Adductor Tendon Tears: Surgical Technique and Outcomes in 40 Male Athletes. Orthop J Sports Med 2021; 9:23259671211042024. [PMID: 34671690 PMCID: PMC8521433 DOI: 10.1177/23259671211042024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Accepted: 06/08/2021] [Indexed: 11/16/2022] Open
Abstract
Background: The optimal treatment for complete avulsions of the proximal adductor longus (AL) is still debatable, and different operative and nonoperative treatment options have been suggested. Purpose: To report surgical techniques and functional outcomes of a series of athletes who were treated operatively for proximal AL tears. Study Design: Case series; Level of evidence, 4. Methods: A retrospective evaluation of patients who underwent surgical repair of complete proximal AL tear with concomitant distal fascial release with or without lesions of the neighboring soft tissue structures was performed. This included preinjury Tegner score, age, number of tendons involved, time interval from injury to surgery, and postoperative complications. Self-reported outcomes were defined based on the ability to regain sports activities (excellent, good, moderate, fair, or poor). Between-group comparisons were performed to identify factors associated with improved outcomes. The Mann-Whitney nonparametric test was used for comparing continuous variables, and the Fisher exact test was used for comparing nominal variables. Results: A total of 40 male athletes were included in the evaluation, with an average follow-up of 11 months (range, 6 months-8 years). Self-reported outcome was excellent in 23 (57.5%), good in 13 (32.5%), and moderate in 4 (10%) patients. Comparisons between patients with excellent versus good/moderate outcomes revealed nonsignificant differences regarding age at injury and preinjury Tegner score. Athletes with excellent outcomes received surgery sooner after the injury compared with athletes with good/moderate outcomes (2.4 ± 1.8 vs 11.4 ± 11.0 weeks, respectively; P < .01). Conclusion: Surgical repair for complete proximal AL tears with a concomitant distal fascial release resulted in outcomes rated as good or excellent in 90% of the cases. This treatment should be considered particularly in high-level athletes with a clear tendon retraction and within the first month after the injury. Further research is nevertheless needed to compare these outcomes with other treatment alternatives to better define criteria advocating surgery.
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The Activation of Gluteal, Thigh, and Lower Back Muscles in Different Squat Variations Performed by Competitive Bodybuilders: Implications for Resistance Training. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2021; 18:ijerph18020772. [PMID: 33477561 PMCID: PMC7831128 DOI: 10.3390/ijerph18020772] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Revised: 01/12/2021] [Accepted: 01/14/2021] [Indexed: 01/12/2023]
Abstract
The present study investigated the activation of gluteal, thigh, and lower back muscles in different squat variations. Ten male competitive bodybuilders perform back-squat at full (full-BS) or parallel (parallel-BS) depth, using large feet-stance (sumo-BS), and enhancing the feet external rotation (external-rotated-sumo-BS) and front-squat (FS) at 80% 1-RM. The normalized surface electromyographic root-mean-square (sEMG RMS) amplitude of gluteus maximus, gluteus medius, rectus femoris, vastus lateralis, vastus medialis, adductor longus, longissimus, and iliocostalis was recorded during both the ascending and descending phase of each exercise. During the descending phase, greater sEMG RMS amplitude of gluteus maximus and gluteus medius was found in FS vs. all other exercises (p < 0.05). Additionally, FS elicited iliocostalis more than all other exercises. During the ascending phase, both sumo-BS and external-rotated-sumo-BS showed greater vastus lateralis and adductor longus activation compared to all other exercises (p < 0.05). Moreover, rectus femoris activation was greater in FS compared to full-BS (p < 0.05). No between-exercise difference was found in vastus medialis and longissimus showed no between-exercise difference. FS needs more backward stabilization during the descending phase. Larger feet-stance increases thigh muscles activity, possibly because of their longer length. These findings show how bodybuilders uniquely recruit muscles when performing different squat variations.
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Surgical Release of the Adductor Longus With or Without Sports Hernia Repair Is a Useful Treatment for Recalcitrant Groin Strains in the Elite Athlete. Orthop J Sports Med 2020; 8:2325967119896104. [PMID: 32047829 PMCID: PMC6985970 DOI: 10.1177/2325967119896104] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Accepted: 07/18/2017] [Indexed: 11/16/2022] Open
Abstract
Background Chronic strain and/or tendinopathy of the adductor longus tendon can be a cause of long-standing groin pain in the elite athlete, resulting in significant time lost from competition. Accurate diagnosis and treatment can expedite return to play. Purpose/Hypothesis To evaluate return to sport and performance in National Collegiate Athletic Association (NCAA) Division I football players and National Football League (NFL) players following adductor longus release with or without sports hernia repair. We hypothesized that adductor release will be an effective method of treatment for recalcitrant groin/adductor pain in these athletes. Study Design Case series; Level of evidence, 4. Methods A cohort study was performed of all NFL players and NCAA Division I college athletes who had undergone an adductor longus tendon release with or without sports hernia repair by 1 of 2 fellowship-trained orthopaedic surgeons between May 1999 and January 2013. All patients reported groin pain below the inguinal ligament and localized to their adductor longus. Symptoms lasted longer than 10 weeks and limited their ability to effectively perform during sport, as assessed by their coach and self-assessment. Questionnaires were given to all 26 patients to assess long-term surgical outcomes. A subgroup analysis was performed for NFL players, in which "performance scores" were calculated according to individual player statistics while playing. Scores obtained before the diagnosis of chronic adductor longus tendinopathy or strain were compared with those after surgery. Patients with prior abdominal or pelvic surgery, radiographic evidence of degenerative joint disease of the hip, labral tears or femoral acetabular impingement, prostatic or urinary tract disease, or nerve entrapment of the ilioinguinal, genitofemoral, or lateral femoral cutaneous nerves were excluded from the study. Results A total of 32 athletes underwent an adductor longus tenotomy during the study period. Of these patients, 28 were college- or professional-level athletes who underwent an adductor longus tenotomy, with a mean ± SD follow-up time of 6.2 ± 4.2 years (range, 12-178 months). Of the 32 patients, 20 had a concomitant sports hernia repair in addition to an adductor longus tenotomy. Thirty-one patients (97%) were able to return to their previous sport, and 30 (94%) were able to return at their previous level of play. Thirty patients (94%) reported that they were satisfied with their decision to have surgery. No player complained of weakness or a decrease in running speed or power. Mean return to play was 12 weeks from date of surgery. In the subgroup analysis of 16 NFL players, there were no statistically significant differences for the pre- versus postoperative comparisons of the athlete performance scores (P = .74) and the percentage of the games started versus played (P = .46). After separation of players who had a concomitant hernia repair from players who did not, there was no statistically significant difference in performance scores or percentages of games started. Conclusion In this study of elite athletes, adductor longus tenotomy with or without a concomitant sports hernia repair provided overall acceptable and excellent results. Athletes were able to return to their previous level of athletic competition and performance with consistent relief of groin pain. Return to play in an NFL game averaged 12 weeks following surgery.
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Abstract
Background: Adductor longus tendinopathy is a well-known etiology of chronic groin pain in elite athletes. Surgery is indicated for those who fail conservative treatment. No studies to date have evaluated the feasibility of an ultrasound-guided release of the proximal adductor longus tendon. Purpose/Hypothesis: The primary aim of this study was to determine the feasibility of an ultrasound-guided selective adductor longus release with a cutting wire. A secondary aim was to determine safety by avoiding injury to adjacent structures. We hypothesized that the proximal adductor longus tendon can be released under ultrasound guidance with a cutting wire without injury to adjacent neurovascular or genitourinary structures. Study Design: Descriptive laboratory study. Methods: Ten adductor longus tendons (5 cadaveric specimens) from 4 males and 1 female between 76 and 89 years of age with a mean body mass index of 21.9 kg/m2 (range, 16.8-29.6 kg/m2) were used during this study. A single experienced physician sonographer performed ultrasound-guided proximal adductor longus tendon releases on all cadaveric specimens using a cutting wire. Dissection was performed by a second physician to determine the completeness of the tendon transections and to detect injury to adjacent neurovascular or genitourinary structures. Results: All 10 adductor longus tendons were transected. Eight of 10 transections were complete, whereas in 2 transections, >99% of the tendon was transected. There were no injuries to adjacent genitourinary or neurovascular structures. Conclusion: Ultrasound-guided adductor tendon release is feasible and safe in a cadaveric model. Further translational research should be performed to determine whether these results can be replicated in the clinical setting. Clinical Relevance: Adductor longus tendinopathy frequently requires surgical intervention and prolonged time away from sport. The present study suggests that a selective adductor longus tendon release can be performed with ultrasound guidance. This procedure warrants further translational research to explore its use in clinical practice.
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Comparative Effects of 4 Single-Leg Squat Exercises in Subjects With Gluteus Medius Weakness. J Sport Rehabil 2018; 27:513-519. [PMID: 28714757 DOI: 10.1123/jsr.2016-0193] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
CONTEXT Of the weight-bearing exercises, single-leg squats (SLSs) represent one of the most commonly used hip-strengthening exercises that require more gluteus medius (GMED) activity. To date, no studies have investigated how the 4 SLS exercises affect muscle imbalance of GMED, tensor fasciae latae (TFL), and adductor longus (AL), and kinematics of hip. OBJECTIVE To investigate the hip muscle activities, onset time, and kinematics during 4 different SLS exercises (unilateral squat, unilateral wall-squat [UWS], lateral step-down, and front step-down) in subjects with GMED weakness. DESIGN Repeated-measures experimental design. SETTING Research laboratory. PARTICIPANTS Twenty-two subjects (11 males and 11 females) participated in this study and were compared using 1-way repeated-measures analysis of variance. MAIN OUTCOME MEASURES Surface electromyography was used to measure the muscle activities and onset time of the GMED, TFL, and AL, and 3-dimensional motion tracking system was used to measure the hip adduction and internal/external rotation angles during SLS exercises. One-way repeated-measures analysis of variance was used at a significance level of P < .05. RESULTS The UWS produced higher GMED/TFL activity ratio and lower GMED/TFL onset time ratio than in the other 3 exercises (P < .05). No difference in GMED/AL activity ratio and GMED/AL onset time ratio was observed. The hip adduction angle was greater in UWS than in the other 3 exercises (P < .05). As for the hip internal/external rotation, lateral step-down exhibited higher hip internal rotation angle than front step-down (P < .05). CONCLUSION The UWS may be recommended as an effective exercise for the subjects with GMED weakness, but they should take care to avoid excessive hip adduction during the exercise.
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Lower-Extremity Muscle Activity, Kinematics, and Dynamic Postural Control in Individuals With Patellofemoral Pain. J Sport Rehabil 2018; 27:505-512. [PMID: 28714838 DOI: 10.1123/jsr.2016-0100] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
CONTEXT Altered lower-extremity muscle activity has been associated with lower-extremity kinematics in individuals with patellofemoral pain (PFP). However, few studies have examined these relationships, and the results are inconsistent. OBJECTIVE To compare the lower-extremity muscle activity, kinematics, pain level, and reach distance during the anterior reach of the star excursion balance test (SEBT) between participants with PFP and healthy individuals (control [CON] group). DESIGN Case control. SETTING Research laboratory. PARTICIPANTS Twenty-eight (PFP = 14 and CON = 14) participants volunteered. INTERVENTION Each participant performed 3 maximal voluntary isometric contractions of the gluteus maximus, gluteus medius (GMED), adductor longus (AL), and vastus medialis, and 5 anterior reaches of the SEBT. MAIN OUTCOME MEASURES Three-dimensional joint kinematics of the hip and knee at the time of touchdown of the SEBT and integrated electromyography of each muscle were recorded during the descent phase of the SEBT. Coactivation ratios between the GMED and AL were calculated (GMED/AL). Pain level was assessed at the baseline and during performance of the SEBT, using a visual analog scale. RESULTS Participants with PFP demonstrated decreased GMED/AL coactivation ratio (P = .01) and shorter reach distance (P = .01) during anterior reach of the SEBT compared with the CON group. Participants with PFP demonstrated higher pain levels at baseline (P = .03) and during test performance (P < .001) compared with the CON group and increased pain level during the test performance compared with the baseline (P < .001). No other significant differences were observed. CONCLUSIONS There were alterations in muscle activity during SEBT performance, suggesting that overactivity of AL relative to GMED is a unique neural recruitment pattern in those with PFP. However, hip and knee joint kinematics did not seem to contribute to deficits in the anterior reach distance, suggesting a need for continued assessment of these deficiencies.
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Abstract
A possible link between soccer-specific injuries, such as groin pain and the action of hip adductor muscles has been suggested. This study aimed to investigate neuromuscular activation of the adductor magnus (AM) and longus (AL) muscles during instep and side-foot soccer kicks. Eight university soccer players performed the two types of kick at 50%, 75% and 100% of the maximal ball speed. Surface electromyography (EMG) was recorded from the AM, AL, vastus lateralis (VL) and biceps femoris (BF) muscles of both kicking and supporting legs and the kicking motions were three-dimensionally captured. In the kicking leg, an increase in surface EMG with an increase in ball speed during instep kicking was noted in the AM muscle (p < 0.016), but not in AL, VL or BF muscles (p > 0.016). In the supporting leg, surface EMG of both AM and AL muscles was significantly increased with an increase in the ball speed before ball impact during both instep and side-foot kicks (p < 0.016). These results suggest that hip adductor muscles markedly contribute to either the kicking or supporting leg to emphasise the action of soccer kicks.
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Characteristics of acute groin injuries in the adductor muscles: A detailed MRI study in athletes. Scand J Med Sci Sports 2017. [PMID: 28649700 DOI: 10.1111/sms.12936] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Acute adductor injuries account for the majority of acute groin injuries; however, little is known about specific injury characteristics, which could be important for the understanding of etiology and management of these injuries. The study aim was to describe acute adductor injuries in athletes using magnetic resonance imaging (MRI). Male athletes with acute groin pain and an MRI confirmed acute adductor muscle injury were prospectively included. MRI was performed within 7 days of injury using a standardized protocol and a reliable assessment approach. 156 athletes presented with acute groin pain of which 71 athletes were included, median age 27 years (range 18-37). There were 46 isolated muscle injuries and 25 athletes with multiple adductor injuries. In total, 111 acute adductor muscle injuries were recorded; 62 adductor longus, 18 adductor brevis, 17 pectineus, 9 obturator externus, 4 gracilis, and 1 adductor magnus injury. Adductor longus injuries occurred at three main injury locations; proximal insertion (26%), intramuscular musculo-tendinous junction (MTJ) of the proximal tendon (26%) and the MTJ of the distal tendon (37%). Intramuscular tendon injury was seen in one case. At the proximal insertion, 12 of 16 injuries were complete avulsions. This study shows that acute adductor injuries generally occur in isolation from other muscle groups. Adductor longus is the most frequently injured muscle in isolation and in combination with other adductor muscle injuries. Three characteristic adductor longus injury locations were observed on MRI, with avulsion injuries accounting for three-quarters of injuries at the proximal insertion, and intramuscular tendon injury was uncommon.
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DYNAMIC HIP ADDUCTION, ABDUCTION AND ABDOMINAL EXERCISES FROM THE HOLMICH GROIN-INJURY PREVENTION PROGRAM ARE INTENSE ENOUGH TO BE CONSIDERED STRENGTHENING EXERCISES - A CROSS-SECTIONAL STUDY. Int J Sports Phys Ther 2017; 12:371-380. [PMID: 28593090 PMCID: PMC5455186] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023] Open
Abstract
BACKGROUND Training intensity is an important variable in strength training and above 80% of one repetition maximum is recommended for promoting strength for athletes. Four dynamic and two isometric on-field exercises are included in the Hölmich groin-injury prevention study that initially failed to show a reduction in groin injuries in soccer players. It has been speculated that exercise-intensity in this groin-injury prevention program was too low to induce the strength gains necessary to protect against groin-related injuries. PURPOSE To estimate the intensity of the six exercises from the Hölmich program using electromyography (EMG) and possibly categorize them as strength-training exercises. STUDY DESIGN Cross-sectional study. METHODS 21 adult male soccer players training >5 hours weekly were included. Surface-EMG was recorded from adductor longus, gluteus medius, rectus abdominis and external obliques during isometric adduction against a football placed between the ankles (IBA), isometric adduction against a football placed between the knees (IBK), folding knife (FK), cross-country skiing on one leg (CCS), adduction partner (ADP) and abduction partner (ABP). The EMG-signals were normalized (nEMG) to an isometric maximal voluntary contraction for each tested muscle. RESULTS Adductor longus activity during IBA was 84% nEMG (95% CI: 70-98) and during IBK it was 118% nEMG (95% CI 106-130). For the dynamic exercises, ADP evoked 87% nEMG (95% CI 69-105) in adductor longus, ABP evoked 88% nEMG (95% CI 76-100) in gluteus medius, FK evoked 82% nEMG (95% CI 68-96) rectus abdominis, and 101% nEMG (95% CI 85-118) in external obliques. During CSS < 37% nEMG was evoked from all muscles. CONCLUSION These data suggest that exercise-intensity of all the six investigated exercises in the Hölmich groin injury prevention program, except cross-county skiing, is sufficient to be considered strength-training for specific muscle groups in and around the groin region. LEVEL OF EVIDENCE 3.
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Estrogen induces axonal outgrowth in the nucleus retroambiguus-lumbosacral motoneuronal pathway in the adult female cat. J Neurosci 1997; 17:1122-36. [PMID: 8994066 PMCID: PMC6573176] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
In 1995, we discovered a new pathway in the cat, which originates from the nucleus retroambiguus (NRA) and terminates in a distinct set of lumbosacral hindlimb, axial, and pelvic floor motoneuronal cell groups [VanderHorst VGJM, Holstege G (1995) Caudal medullary pathways to lumbosacral motoneuronal cell groups in the cat: evidence for direct projections possibly representing the final common pathway for lordosis. J Comp Neurol 359:457-475]. The NRA is a compact group of interneurons located laterally in the caudal medulla oblongata. Its projection to lumbosacral motoneurons is thought to represent the final common pathway for male mounting and for female receptive or lordosis behavior. However, females only display lordosis behavior. However, females only display lordosis behavior when they are in estrus, which suggests that the NRA-lumbosacral pathway is only active during estrus. This raised the question of whether estrogen affects this pathway. The effect of estrogen on the NRA-lumbosacral projection was studied light microscopically, using wheat-germ agglutinin horseradish peroxidase (WGA-HRP) as a tracer. The rubrospinal pathway served as control. The density of labeled NRA fibers in their target hindlimb motoneuronal cell groups appeared abundant in estrous and very weak in nonestrous cats. Such differences were not found in the rubrospinal pathway. For electron microscopical study, the NRA projection to the semi-membranosus motoneuronal cell group was selected. In this cell group, an almost ninefold increase of labeled profiles was found in estrous versus nonestrous cats. Moreover, the semimembranous motoneuronal cell group contained labeled growth cones in estrous, but not in nonestrous, cats. The present study is the first to show that estrogen induces axonal outgrowth of a precisely identified pathway in the adult mammalian central nervous system. The possible mechanisms underlying this outgrowth are discussed.
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