Adductor longus and brevis lesion in an amateur soccer player: platelet rich plasma and multifractioned hyaluronic acid injections to enhance clinical recovery.

Groin pain is a common issue in athletes, with a particularly high incidence in male soccer players. Adductor muscles are the most involved site of the groin, accounting for up to one-fourth of muscle injuries of that region. Physical therapy and rehabilitation programs for adductor-related groin pain using active exercises are effective in getting athletes back to sport. However, the return-to-play time varies according to the injury severity. Minor lesions can recover in 1-2 weeks, while severer injuries require 8-12 weeks. To enhance tendon healing and shorten the return to play time, intrandentinous injections of Platelet Rich Plasma (PRP) have been proposed. An increasing body of evidence in literature have shown efficacy of platelet rich plasma in aiding the healing process in tendinopathies. Similarly, more recent evidences have proven hyaluronic (HA) acid to have anti-inflammatory, proliferative, repairing, and analgesic effects. This case report presents the clinical application of combined PRP and a multifractioned (a mixture of different molecular weights) HA in a 24-year-old athlete suffering from a hip adductor rupture.

Do the Testing Posture and the Grip Modality Influence the Shoulder Maximal Voluntary Isometric Contraction?

Assessing and monitoring shoulder strength is extremely important during rehabilitation. A fixed dynamometer represents a valid and inexpensive assessment method. However, it has not been studied whether posture and grip modality influence shoulder muscle strength. The aim of this study was to compare shoulder strength values between sitting and standing positions and between the handle and cuff grip modalities. A total of 40 volunteers were divided into a posture (PG) and a handle-cuff group (HCG). Participants in the PG were asked to perform a maximum voluntary isometric contraction (MVIC) for shoulder flexion, extension, ab-adduction, and intra-extra rotation in standing and sitting positions. The HCG participants were tested in a standing position while holding a handle or with a cuff around their wrist. PG showed higher forces in the standing position for shoulder flexion (p = 0.009); internal rotation showed higher values in the sitting position (p = 0.003). ER/IR ratio was significantly higher in the standing position (p < 0.001). HCG showed higher significant forces during cuff modality in all positions and grip modalities, including the ER/IR ratio (p < 0.05). Different body positions and grip modalities influenced the assessment of shoulder strength as recorded by a fixed dynamometer; therefore, these factors should be carefully considered when carrying out a shoulder strength assessment, and we encourage the development of assessment guidelines to make future clinical trial results comparable.

Criteria for Return-to-Play (RTP) after Rotator Cuff Surgery: A Systematic Review of Literature.

This systematic review of the literature aimed to highlight which criteria are described in the literature to define when a patient, after rotator cuff repair (RCR), is ready for return-to-play (RTP), which includes return to unrestricted activities, return to work, leisure, and sport activities. An online systematic search on the US National Library of Medicine (PubMed/MEDLINE), SCOPUS, Web of Science (WOS), and the Cochrane Database of Systematic Reviews, was performed with no data limit until December 2021. A total of 24 studies that reported at least one criterion after RCR were included. Nine criteria were identified and among these, the most reported criterion was the time from surgery, which was used by 78% of the studies; time from surgery was used as the only criterion by 54% of the studies, and in combination with other criteria, in 24% of the studies. Strength and ROM were the most reported criteria after time (25%). These results are in line with a previous systematic review that aimed to identify RTP criteria after surgical shoulder stabilization and with a recent scoping review that investigated RTP criteria among athletes after RCR and anterior shoulder stabilization. Compared to this latest scoping review, our study adds the methodological strength of being conducted according to the Prisma guidelines; furthermore, our study included both athletes and non-athletes to provide a comprehensive view of the criteria used after RCR; moreover, ten additional recent manuscripts were examined with respect to the scoping review.

Physical Exercise and Mental Health: The Routes of a Reciprocal Relation.

Sport participation and exercise practice are considered to be beneficial for mental status, yielding an improved mood and better quality of life. On the other hand, good mental fitness is thought to lead to better physical status and sport performance. The key aim of this narrative review is to provide an unstructured overview on the topic with special considerations on the role of mental and physical health to summarize the evidence on their reciprocal influence. While very few papers describe the role of mental health measures in affecting physical performance, more evidence is available concerning the effect of exercise and sport in improving mental health outcomes. Furthermore, there is a consistent role of depressive and anxiety symptoms in influencing the risk of sport injury in either recreational or elite athletes. Moreover, the importance of investigating mental health issues in elite and retired athletes is highlighted. On the basis of the available literature, several biases were found to affect the provided evidence mainly because of the complexity of a proper study design in this field.

Effects of Accentuated Eccentric Training vs Plyometric Training on Performance of Young Elite Fencers.

The aim of the study was to evaluate the effects of 6-weeks accentuated eccentric training, using a rotary inertial device, on range of motion, assessed with Inter Malleolar Distance test, anthropometry, lower limb explosive and reactive strength, assessed with Squat Jump, Countermovement Jump and 7-Repeated Hop tests, in young elite fencers. Moreover, the effects on hamstring eccentric strength and two technical fencing movements, lunge and advance-advance lunge, were evaluated with motion analysis. The second aim was to evaluate the duration of the accentuated eccentric training residual effects, 6 weeks after the end of the training. Fifty-four male fencers were randomly assigned either to the Inertial Group (IG; n = 26; aged 17.3 ± 1.9 years) such as experimental group, or to the Plyometric Group (PG; n = 28; aged 17.6 ± 2.7 years) such as control group. IG carried out four exercises using the rotary inertial device attached to their waist by a rope. PG carried out several plyometric exercises at the same time in which the IG performed the accentuated eccentric training. MANOVA showed significant improvements in the vertical jumps height post training, with no differences between IG and PG. Significant improvements for technical movements, lunge distance (p = 0.006) and advance-advance lunge distance (p = 0.00005), were found within-group and between-groups (p = 0.00001), with higher improvements in IG than in PG. The univariate analysis showed a significant improvement in lower limb range of motion with higher increase in IG than in PG. The main findings were the significant improvement in lunge and advance-advance lunge distance, maintaining with the same execution time. These results suggested that it is important to apply accentuated eccentric load on specific sport movements.

Biohumoral Indicators Influenced by Physical Activity in the Elderly.

In the scientific landscape, there is a growing interest in defining the role of several biomolecules and humoral indicators of the aging process and in the modifications of these biomarkers induced by physical activity and exercise. The main aim of the present narrative review is to collect the available evidence on the biohumoral indicators that could be modified by physical activity (PA) in the elderly. Online databases including Pubmed, Web of science (Medline), and Scopus were searched for relevant articles published in the last five years in English. Keywords and combination of these used for the search were the following: "biological", "indicators", "markers", "physical", "activity", and "elderly". Thirty-four papers were analyzed for inclusion. Twenty-nine studies were included and divided into four categories: cardiovascular (CV) biomarkers, metabolic biomarkers, inflammatory markers-oxidative stress molecules, and other markers. There are many distinct biomarkers influenced by PA in the elderly, with promising results concerning the metabolic and CV indexes, as a growing number of studies demonstrate the role of PA on improving parameters related to heart function and CV risk like atherogenic lipid profile. Furthermore, it is also a verified hypothesis that PA is able to modify the inflammatory status of the subject by decreasing the levels of pro-inflammatory cytokines, including interleukin-1 (IL-1), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-α). PA seems also to be able to have a direct effect on the immune system. There is a strong evidence of a positive effect of PA on the health of elderly people that could be evidenced and "quantified" by the modifications of the levels of several biohumoral indicators.

Isoinertial Eccentric-Overload Training in Young Soccer Players: Effects on Strength, Sprint, Change of Direction, Agility and Soccer Shooting Precision.

The isoinertial training method owes its efficacy to an accommodated resistance and optimal individualized eccentric overload. The aim of this study was to assess the effects of a 6-week isoinertial eccentric-overload training program - using a flywheel inertial device during the execution of specific soccer exercises - on explosive and reactive strength, sprint ability, change of direction (COD) performance and soccer shooting precision. Thirty-four junior soccer players were randomly assigned to a plyometric training group (PT) (n = 16, aged 13.36 ± 0.80), which underwent a six-week traditional soccer training program, and a flywheel eccentric overload group (FEO) (n = 18, aged 13.21 ± 1.21), which received additional training consisting of two inertial eccentric-overload training sessions per week. Pre and post intervention tests were carried out to assess explosive and reactive strength, sprint ability, COD ability, agility using the Y-agility test (YT) and soccer shooting precision. The FEO showed significantly higher values than the PT in squat jump height (SJh) (p = 0.01), drop jump height (DJh) (p = 0.003), 7 repeated hop test heights (p = 0.001), the Illinois test (ILL) (p = 0.001), and the Loughborough Soccer Shooting Test (SHOT) (p = 0.02). Finally, the FEO showed significant between-group differences in DJh (p = 0.007), ILL (p = 0.0002), YT (p = 0.002), a linear sprint test (SPRINT) (p = 0.001), and SHOT (p = 0.003). These results confirmed the positive effect of isoinertial training. The use of an isoinertial device to overload multidirectional movements in specific sport conditions leads to greater performance improvements than conventional soccer training. The absence of knowledge of the eccentric overload applied by the isoinertial device, which is different in any exercise repetition, may stimulate the athlete's neural adaptations, improving their soccer skills and in particular their soccer shooting precision.

Central and Peripheral Neuromuscular Adaptations to Ageing.

Ageing is accompanied by a severe muscle function decline presumably caused by structural and functional adaptations at the central and peripheral level. Although researchers have reported an extensive analysis of the alterations involving muscle intrinsic properties, only a limited number of studies have recognised the importance of the central nervous system, and its reorganisation, on neuromuscular decline. Neural changes, such as degeneration of the human cortex and function of spinal circuitry, as well as the remodelling of the neuromuscular junction and motor units, appear to play a fundamental role in muscle quality decay and culminate with considerable impairments in voluntary activation and motor performance. Modern diagnostic techniques have provided indisputable evidence of a structural and morphological rearrangement of the central nervous system during ageing. Nevertheless, there is no clear insight on how such structural reorganisation contributes to the age-related functional decline and whether it is a result of a neural malfunction or serves as a compensatory mechanism to preserve motor control and performance in the elderly population. Combining leading-edge techniques such as high-density surface electromyography (EMG) and improved diagnostic procedures such as functional magnetic resonance imaging (fMRI) or high-resolution electroencephalography (EEG) could be essential to address the unresolved controversies and achieve an extensive understanding of the relationship between neural adaptations and muscle decline.

Does Warm-up Type Matter? A Comparison between Traditional and Functional Inertial Warm-up in Young Soccer Players.

Functional inertial training, a popular high-intensity training mode, provides high neuromuscular activation, developing proprioception, postural control, power, and sprint time. Aim of the study was to assess the acute effects of two types of warm-up (WU), inertial warm-up (IWU) vs. traditional warm-up (TWU), on explosive and reactive strength, sprint, and Change of Directions (COD) in young soccer players. In a randomized cross-over design study, twelve soccer players (aged 13.3 ± 0.7) performed 16 min of IWU and 16 min of TWU. IWU and TWU were spaced two weeks apart. Pre and post intervention tests, aimed at assessing explosive and reactive strength, sprint, and COD ability included: Squat Jump test (SJ), Countermovement Jump test (CMJ), Drop Jump test (DJ), Seven Repetition Hopping test (7R-HOP), 40 m-sprint test (40 m), and Illinois Agility Test (IAT). RM-ANOVA, used to compare differences between IWU and TWU effects (the level of significance set at ρ ≤ 0.05), showed enhanced performance after the IWU compared to the TWU. In addition, the effects of the IWU on performance lasted longer after the IWU than after the TWU. For IAT, the enhanced effects of IWU on performance lasted up to ten minutes after the administration of the IWU. Our results suggest that IWU affects functional changes displaying earlier adaptation in explosive and reactive strength with longer lasting effects compared to TWU and it could be recommended in young soccer athletes as a WU procedure.

No Relationship Between Preoperative and Early Postoperative Strength After ACL Reconstruction.

CONTEXT: All rehabilitative programs before anterior cruciate ligament (ACL) reconstructive surgery, which are focused on recovery of proprioception and muscular strength, are defined as prehabilitation. While it has shown that prehabilitation positively affects the overall outcome after ACL reconstruction, it is still controversial whether preoperatively enhancing quadriceps strength has some beneficial effect on postoperative strength, mainly during the first period. OBJECTIVE: To determine whether there is any relationship between preoperative and early postoperative quadriceps strength. DESIGN: Case control. SETTING: University research laboratory. PARTICIPANTS: Fifty-nine males (18-33 y; age: 23.69 [0.71] y) who underwent ACL reconstruction with patellar-tendon autograft were examined the day before surgery, and at 60 and 90 days after surgery. MAIN OUTCOME MEASURES: The limb symmetry index (LSI) was quantified for maximal voluntary isometric contraction of the knee extensor muscles and of the knee flexor muscles at 90° joint angle. A k-means analysis was performed on either quadriceps or hamstrings LSI before surgery to classify the patients in high and low preoperative LSI clusters. Differences in postoperative LSI were then evaluated between the high and low preoperative LSI clusters. RESULTS: Following surgery, there were no differences in the quadriceps LSI between patients with high and low preoperative quadriceps LSI. Sixty days after surgery, the hamstrings LSI was higher in patients with high than low preoperative hamstrings LSI (84.0 [13.0]% vs 75.4 [15.9]%; P < .05). CONCLUSIONS: Findings suggest that quadriceps strength deficit is related to the ACL injury and increases further after the reconstruction without any correlation between the preoperative and postoperative values. Therefore, it appears that there is no need to delay surgery in order to increase the preoperative quadriceps strength before surgery.

The Effect of an Orthotic Device for Balancing Neck Muscles During Daily Office Tasks.

OBJECTIVE: This study aimed at evaluating the acute effect of the combined and single use of two orthotic devices (neck balance system [NBS] and lumbar support [LS]) on muscle activity of neck and back muscles during typical computer working tasks. BACKGROUND: An excessive activation of neck muscles could threaten the balance between agonist and antagonist muscles, resulting in a lower stability of the head and possibly leading to neck pain. At present, no study evaluated the effect of a specific orthotic device in reducing neck muscles activation. METHODS: Surface electromyography (sEMG) from neck flexor (sternocleidomastoid [SCMD]) and extensor muscles (semispinalis capitis [SPC]) and back extensor muscles (erector spinae [ERS]) of 20 healthy individuals was recorded during three computer working tasks performed with the NBS, with NBS and LS, with the LS, and without devices (ND). RESULTS: In the NBS condition, the SPC showed a reduced activation (NBS = 3.97%; NBS + LS = 4.49%; LS = 4.48%; ND = 4.61% of the maximal voluntary contraction) compared to the other conditions. CONCLUSIONS: The use of the NBS promotes a reduction of neck extensor muscles, possibly due to the inertial mass added in the occipital part of the head, producing an external neck extensor moment that cooperates with that produced by neck extensor muscles. APPLICATION: Orthotic devices such as the NBS may be used by computer workers to reduce the activation of their neck extensor muscles and possible risks of developing neck pain.

Whole body vibration of different frequencies inhibits H-reflex but does not affect voluntary activation.

This study aimed to investigate the effects of whole-body vibration (WBV) at a frequency spectrum from 20 to 50 Hz on the Hoffmann (H) reflex and the voluntary motor output of ankle plantar-flexor muscles. A single-group (n: 8), repeated measures design was adopted with four conditions: standing (no vibration), 20, 35 and 50 Hz, each lasting one minute. H-reflex of the soleus muscle, maximal voluntary contraction (MVC) and central activation ratio (CAR) of the plantar-flexors were evaluated before, 1 and 5 min after each frequency condition. H-reflex decreased by 36.7% at 20 Hz, by 28% at 35 Hz, and by 34.8% at 50 Hz after one minute from WBV compared to baseline. Neither MVC nor CAR changed after WBV at all frequency conditions. The short-term, acute inhibition of the H-reflex after WBV at 20, 35 and 50 Hz suggested that decreased excitability of spinal motoneurons is not frequency dependent. On the other hand, the lack of vibration induced effects on MVC and CAR indicated that a 1-min WBV stimulus is not sufficient to affect the voluntary motor output.

Acute effect of whole body vibration on postural control in congenitally blind subjects: a preliminary evidence.

PURPOSE: The purpose of this study was to investigate the acute effects of whole body vibration at optimal frequency, on postural control in blind subjects. METHOD: Twenty-four participants, 12 congenital blind males (Experimental Group), and 12 non-disabled males with no visual impairment (Control Groups) were recruited. The area of the ellipse and the total distance of the center of pressure displacements, as postural control parameters, were evaluated at baseline (T0), immediately after the vibration (T1), after 10 min (T10) and after 20 min (T20). Whole body vibration protocol consisted into 5 sets of 1 min for each vibration, with 1 min rest between each set on a vibrating platform. RESULTS: The total distance of center of pressure showed a significant difference (p < 0.05) amongst groups, while the area remained constant. No significant differences were detected among times of assessments, or in the interaction group × time. CONCLUSION: No impairments in static balance were found after an acute bout of whole body vibration at optimal frequency in blind subjects and, consequently, whole body vibration may be considered as a safe application in individuals who are blind.

Effectiveness of a new cervical pillow on pain and sleep quality in recreational athletes with chronic mechanical neck pain: a preliminary comparative study.

BACKGROUND: The aim of this intervention study was to determine the effects of a new experimental cervical pillow, on symptomatic adults affected by chronic mechanical neck pain. METHODS: Twelve recreational athletes of both sexes (mean age 40.5 years; range 35-55), affected by grade II chronic mechanical neck pain, were evaluated with a daily diary type of self-report questionnaire, which incorporated an 11-point Numerical Rating Pain Scale, to collect the primary outcome measures of pre- and post-sleep neck pain and with the Neck Pain Disability Scale. Tympanic temperature, heart rate (HR) variability continuous monitoring during sleep, overnight pillow comfort and sleep quality were assessed. RESULTS: Average weekly scores in overall questionnaires, tympanic temperature and the HR low frequency (LF) / high frequency (HF) ratio were significantly lower (P<0.05) after the use of the DM2 pillow than the own pillow. The 80% of participants considered the DM2 "perfectly comfortable" and reported a "good" quality of sleep lying over it. CONCLUSIONS: The use of an appropriate pillow is a determinant factor in relieving neck pain, improving LF/HF ratio and enhancing-vagal activity, promoting deeper stages during the sleep. The shape of this pillow maintains an appropriate cervical curvature, reduces intra-disc pressure allowing a better distribution of loads between cervical discs. The round shaped portion of the pillow, facilitates breathing and avoids the narrowing of the airway due to the incorrect position during the sleep. The peculiar material of the DM2 pillow, contributed to lower brain temperature promoting dry heat loss from the head to the pillow, reducing sweating.

Effects of early whole-body vibration treatment on knee neuromuscular function and postural control after anterior cruciate ligament reconstruction: A randomized controlled trial.

OBJECTIVE: To assess the effects of adding a whole-body vibration protocol at optimal frequency (WBV-OF) to a traditional rehabilitation programme (TRP) early after anterior cruciate ligament reconstruction, on maximal strength and balance, in comparison with a traditional rehabilitation programme. DESIGN: A total of 34 anterior cruciate ligament reconstructed patients with hamstring-tendon graft underwent either 4 weeks of WBV-OF training in addition to a traditional rehabilitation programme, or a traditional rehabilitation programme only, starting from the first month after surgery. Patients were assessed for maximal voluntary isometric strength during both knee extension and flexion and for balance on a force platform before, 1 month after treatment and at 3-month follow-up. RESULTS: Strength symmetry of the knee flexor muscles improved in WBV-OF+TRP patients more than in TRP patients 1 month after treatment (mean 66% (standard deviation (SD) 15) vs 58% SD 13), and also at the 3-month follow-up (mean 77% (SD 15) vs 64% (SD 15)), with no differences in balance improvements between the groups. CONCLUSIONS: Adding 4-weeks of WBV-OF to a traditional rehabilitation programme 1 month after surgery is effective in improving muscle strength of the knee flexor muscles. This early intervention may be incorporated into current rehabilitation to facilitate early strength recovery of anterior cruciate ligament reconstructed patients.

Efficacy of eccentric exercise in lower limb tendinopathies in athletes.

Tendinopathies are among the most frequent sport injuries, therefore their correct treatment is a crucial issue in sports medicine practice. In most of the cases, these multifactorial conditions are related to overuse and characterized by activity-induced pain, local tenderness and swelling. Although tendinopathies are common, their treatment is not easy. Currently, it is generally accepted that their management should include early functional exercises. Eccentric exercise (EE) is considered a fundamental therapeutic resource, especially for the treatment of Achilles and patellar tendinopathies. This article focuses on the use of EE for the treatment and prevention of the lower limb tendinopathies, evaluates the existing programs and their efficacy, and reviews the possible mechanisms of the healing process and the action of EE on tendon structure. EE-based treatments are useful to improve symptoms and function in lower limb tendinopathies, but more evidence is still required to devise an adequate dose-response model and to determine their long-term effects.

Asymmetrical Lower Extremity Loading Early After Anterior Cruciate Ligament Reconstruction Is a Significant Predictor of Asymmetrical Loading at the Time of Return to Sport.

OBJECTIVES: The aim of this study was to examine whether asymmetrical lower limb loading early after anterior cruciate ligament reconstruction (1 mo) can predict asymmetrical lower limb loading at the time of return to sport (6 mos) and whether other early predictors as knee joint range of motion or maximal isometric strength affect this relationship. DESIGN: Ground reaction forces were measured during a sit-to-stand task 1 mo after anterior cruciate ligament reconstruction and a vertical countermovement jump 6 mos after anterior cruciate ligament reconstruction in 58 athletes. Other early postoperative measurements were knee joint range of motion (2 wks, 1 mo, and 2 mos after surgery) and maximal isometric strength of the knee extensor and flexor muscles (2 mos after surgery). Linear regression models were developed using side-to-side limb symmetry index (LSI) of countermovement jump as the dependent variable. RESULTS: LSI of sit-to-stand task 1 mo after surgery was a significant independent predictor of LSI of countermovement jump 6 mos after surgery. After accounting for deficits in knee joint range of motion and LSI of maximal isometric strength (ΔR² = 0.35, P < 0.01), LSI of sit-to-stand task predicted LSI of countermovement jump (ΔR² = 0.14 P < 0.01). CONCLUSIONS: Asymmetrical lower extremity loading 1 mo after anterior cruciate ligament reconstruction is an early predictor of asymmetrical lower extremity loading 6 mos after surgery.

Effects of rhythmical and extra-rhythmical qualities of music on heart rate during stationary bike activities.

BACKGORUND: The aim of this study was to evaluate the effects of rhythmical and extra-rhythmical qualities of music on the heart rate (HR) and rates of perceived exertion (RPE), during sub-maximal stationary bike activity. METHODS: HR of 28 female adult participants was monitored during 3 session of physical activity, performed under 3 different conditions: Hi-BPM (music with 150-170 BPM), RHYTHM (rhythmical qualities only of Hi-BPM condition) and control condition without music (CONTROL). Four parameters were analyzed: the highest HR value (High-HR), High-HR minus starting HR (∆HR), time to reach the 75% of Maximal HR (MHR) (TimeTo75%) and time over 75% MHR (TimeOver75%). HR trend analysis was performed to evaluate differences among the three conditions. OMNI-Cycle Scale was administered to evaluate RPE. RESULTS: MANOVA showed significant differences between the three conditions in TimeTo75%, ∆HR (P<0.01) and TimeOver75% (P<0.05). In RHYTHM and CONTROL conditions after reaching 75% MHR, the HR increase were significantly lower than Hi-BPM (P<0.01). No significant differences were found in OMNI-Cycle Scale scores of Hi-BPM and RHYTHM whereas RPE was significantly higher in CONTROL condition (P<0.05). CONCLUSIONS: Hi-BPM and RHYTHM music allowed a faster reaching of the aerobic training zone compared to CONTROL conditions. Nevertheless, after 75% MHR, extra-rhythmical qualities are necessary to maintain or to increase the working HR levels.

Comparison in Joint-Position Sense and Muscle Coactivation Between Anterior Cruciate Ligament-Deficient and Healthy Individuals.

CONTEXT: Tearing of the anterior cruciate ligament (ACL) may disrupt the ability to recognize the knee position in space during limb-repositioning tasks, which is referred to as joint-position sense (JPS). Impairments in JPS have been shown to be lower during active than passive repositioning tasks, thus suggesting that coactivation patterns of the muscles surrounding the knee might compensate for the disrupted JPS and ensure accurate limb repositioning in ACL-deficient individuals. OBJECTIVE: To investigate muscle coactivation patterns during JPS repositioning tasks in ACL-deficient and healthy individuals. DESIGN: Prospective observational study. SETTING: Functional assessment laboratory. PARTICIPANTS: 8 men age 25 ± 8 y with isolated ACL rupture and 10 men age 30 ± 4 y with no history of knee injury. INTERVENTION: JPS was evaluated by means of an electrogoniometer in a sitting position during either passive or active joint-positioning and -repositioning tasks with a 40° target knee angle. MAIN OUTCOME MEASURES: Root mean square (RMS) of the surface electromyogram from the vastus lateralis and biceps femoris muscles was measured during active joint positioning and repositioning. RESULTS: Healthy participants showed a significant decrease in vastus lateralis RMS (-19%) and an increase in biceps femoris RMS (+26%) during joint repositioning compared with positioning. In contrast, ACL-deficient patients showed no modulation in muscle coactivation between joint positioning and repositioning, although they exhibited significantly lower RMS of the vastus lateralis (injured limb, -28%; uninjured limb, -21%) and higher RMS of the biceps femoris (injured limb, +19%; uninjured limb, +30%) than the healthy participants during joint positioning. CONCLUSIONS: The lack of modulation in muscle coactivation patterns between joint positioning and repositioning in ACL-deficient patients might be attributed to disrupted neural control after the injury-related loss of proprioceptive information. These results should be taken into account in the design of rehabilitation protocols with emphasis on muscle coactivation and JPS.