Effects of the open Latarjet procedure on shoulder kinematics and periscapular muscle activity three months postoperatively.

BACKGROUND: The debate surrounding the influence of the open Latarjet procedure on postoperative scapular motions persists, and there is no evidence regarding its effects on periscapular muscle activation. This study aimed to assess the short-term influence of open Latarjet procedure on scapular kinematics and periscapular muscle activity during arm raising and lowering based on comparisons between patient and healthy athletes. METHODS: 22 healthy male athletes and 22 male athletes scheduled for glenohumeral stabilization surgery by open Latarjet procedure were included. Scapular kinematics, periscapular muscle activities and shoulder-related quality of life were recorded prior to surgery and 3 months postoperatively for the Latarjet group. For the healthy group, same assessments were performed 3 months apart. Bilateral differences in both scapular kinematics and periscapular muscle activation ratios, and Western Ontario Shoulder Instability (WOSI) index were defined as dependent variables. RESULTS: Scapular kinematics of the operated shoulder, namely scapular upward/downward rotation, internal/external rotation and anterior/posterior tilt recorded between 20° and 120° of humerothoracic elevation, showed no alterations 3 months post-surgery (p>0.05), and did not differ from those observed in healthy athletes (p>0.05). Similarly, all periscapular muscle activations were not different within time and between groups (p>0.05). WOSI index of the operated shoulder was significantly improved postoperatively (871.9 ± 443.7 vs. 1346.3 ± 552.3) but remained higher than the WOSI indices of the non-operated shoulder or those of the healthy group (52.7±75.6). CONCLUSION: This study emphasizes the short-term effects of the open Latarjet procedure, demonstrating an improvement in the shoulder-related quality of life 3 months after surgery. Notably, during this period, both kinematics and periscapular muscle activity remained consistent, and similar to the patterns observed for healthy athletes.

Effects of morning and evening physical exercise on subjective and objective sleep quality: an ecological study.

To optimise the relationship between exercise and sleep quality, the intensity of exercise and its proximity to sleep are key factors to manage. Although low-to-moderate exercises promote sleep quality, late-evening vigorous exercise instead of morning should still be avoided. It potentially impacts the objective and subjective markers of sleep quality. In the present study, we investigated the effects of vigorous morning and evening exercise on objective and subjective sleep features in an ecological context. A total of 13 recreational runners (mean [SD] age 27.7 [7.2] years, four females) performed a 45-60 min run (70% maximal aerobic velocity) either in the MORNING (30 min to 2 h after waking-up) or in the EVENING (2 h to 30 min before sleep). The two exercise conditions were separated by a REST day. After each condition, sleep was objectively assessed using an electroencephalographic headband and subjectively using the Spiegel Sleep Inventory. Compared with REST, both MORNING and EVENING exercise increased the time spent in non-rapid eye movement (NREM, +24.9 min and +22.7 min; p = 0.01, η2 = 0.11, respectively). Longer NREM duration was mainly due to sleep stage 2 extension after both MORNING (+20.8 min) and EVENING (+22.8 min) exercise relative to REST (p = 0.02, η2 = 0.12). No other effect of exercise on either objective or subjective sleep could be observed. Exercise, independently of the time at which it takes place, leads to extended NREM sleep without other effects on sleep quality. Considering the crucial role of exercise in achieving good health, sleep hygiene guidelines should be updated to promote exercise at any time of the day.

Effect of Robotic-Assisted Gait at Different Levels of Guidance and Body Weight Support on Lower Limb Joint Kinematics and Coordination.

The Lokomat provides task-oriented therapy for patients with gait disorders. This robotic technology drives the lower limbs in the sagittal plane. However, normative gait also involves motions in the coronal and transverse planes. This study aimed to compare the Lokomat with Treadmill gait through three-dimensional (3D)-joint kinematics and inter-joint coordination. Lower limb kinematics was recorded in 18 healthy participants who walked at 3 km/h on a Treadmill or in a Lokomat with nine combinations of Guidance (30%, 50%, 70%) and bodyweight support (30%, 50%, 70%). Compared to the Treadmill, the Lokomat altered pelvic rotation, decreased pelvis obliquity and hip adduction, and increased ankle rotation. Moreover, the Lokomat resulted in significantly slower velocity at the hip, knee, and ankle flexion compared to the treadmill condition. Moderate to strong correlations were observed between the Treadmill and Lokomat conditions in terms of inter-joint coordination between hip-knee (r = 0.67-0.91), hip-ankle (r = 0.66-0.85), and knee-ankle (r = 0.90-0.95). This study showed that some gait determinants, such as pelvis obliquity, rotation, and hip adduction, are altered when walking with Lokomat in comparison to a Treadmill. Kinematic deviations induced by the Lokomat were most prominent at high levels of bodyweight support. Interestingly, different levels of Guidance did not affect gait kinematics. The present results can help therapists to adequately select settings during Lokomat therapy.

Effects of an 8-week multimodal program on thoracic posture, glenohumeral range of motion and serve performance in competitive young tennis players.

Introduction: Intensive tennis practice is known to generate sport-specific adaptations at the shoulder region and influence the sagittal spinal curvature. However, increased thoracic kyphosis decreases the shoulder functional capacity, which could limit tennis performance. Therefore, the aim of this study was to investigate the effects of an 8-week multimodal program on thoracic posture, glenohumeral range of motion, and serve performance in competitive young tennis players. Methods: Eighteen male and four female players (age: 16.0 ± 2.4 years, height: 170.7 ± 11.0 cm; mass: 62.1 ± 11.5 kg; International Tennis Number: 3-4) performed their regular training during 8 weeks, which was used as a reference period, and implemented a multimodal program including stretching, strengthening, and myofascial release exercises, four times per week during 8 additional weeks, which corresponded to the intervention period. The thoracic curvature angle and mobility, the biacromial and interscapular distances, the glenohumeral range of motion and the tennis serve performance were assessed three times, i.e., before and after the regular training and after the 8-week multimodal program. Results: The results showed that the 8-week regular training had no significant effects on thoracic curvature angle [effect size (ES) = 0.02-0.36, p = 0.06-0.46] and mobility (ES = 0.05-0.26, p = 0.13-0.42), biacromial (ES = 0.05, p = 0.18) and interscapular distances (ES = 0.03, p = 0.45), ranges of motion in glenohumeral internal (ES = 0.04, p = 0.43) and external rotation (ES = 0.43, p = 0.06), and tennis serve accuracy (ES = 0.33, p = 0.07) and velocity (ES = 0.09, p = 0.35). The 8-week multimodal program increased moderately the thoracic mobility (ES = 0.55, p = 0.01), moderately to strongly the serve accuracy and velocity (ES = 0.65, p = 0.003, for both), strongly decreased the interscapular distance (ES = 1.02, p < 0.001), and strongly increased the range of motion in glenohumeral internal (ES = 0.90, p < 0.001) and external rotation (ES = 1.49, p < 0.001). Discussion: These findings indicated that an 8-week multimodal program, including spine and glenohumeral mobility and shoulder girdle strength exercises, performed four times per week during 8 weeks, is moderately relevant to rectify the sagittal thoracic curvature in competitive tennis players, while such a program may help regain the range of motion in glenohumeral rotation without tennis serve performance impairment.

Functional Deficits After Open Latarjet Procedure and Dominance of the Operated Shoulder: An Analysis of 133 Patients.

BACKGROUND: Return to sport after stabilization surgery using the open Latarjet procedure remains challenging. Additional knowledge is needed about postoperative shoulder functional deficits in order to better design return-to-sport programs. PURPOSE: To investigate the effects of the dominance status of the operated shoulder on the shoulder functional profile recovery at 4.5 months after open Latarjet procedure. STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: A retrospective analysis of prospectively collected data was performed. All patients who underwent the open Latarjet procedure between December 2017 and February 2021 were eligible for the study. Functional assessment at 4.5 months after the surgery was performed using the following tests: maximal voluntary isometric contractions in glenohumeral internal and external rotation, upper-quarter Y balance test, unilateral seated shot-put test, and modified closed kinetic chain upper extremity stability test, leading to 10 outcome measures. Patients whose dominant side had undergone surgery and those whose nondominant side had undergone surgery were compared with a group of 68 healthy control participants. RESULTS: A total of 72 patients who underwent an open Latarjet procedure on the dominant side and 61 patients who underwent open Latarjet on the nondominant side were compared with 68 healthy control athletes. In patients whose dominant shoulder had undergone surgery, significant deficits for the dominant side (P < .001) and for the nondominant side (P < .001) were found in 9 of 10 functional outcome measures. Among patients whose operations were on the nondominant shoulder, significant deficits for the nondominant side (P < .001) and for the dominant side (P < .001) were found in 9 and 5 of the 10 functional outcome measures, respectively. CONCLUSION: Regardless of dominance of the stabilized shoulder, persistent deficits in strength, stability, mobility, power, and stroke frequency were observed at 4.5 months postoperatively. Stabilization of the dominant shoulder resulted in residual surgery-related functional impairments on both sides. However, stabilization of the nondominant shoulder resulted in impairments primarily noted in the nondominant, operative shoulder. REGISTRATION: NCT05150379 (ClinicalTrials.gov identifier).

Factors affecting the shoulder functional profile in elite judo athletes.

The aim was to investigate the effects of sex, age, preferred judo technique, dominance, and injury history on the shoulder functional status of elite judo athletes. Sixty-one elite judo athletes (38 males, age: 18.1 ± 1.2 years, body mass: 69.3 ± 13.3 kg, body height: 172.2 ± 9.8 cm, brown belt to second-degree black belt) completed three questionnaires: Western Ontario Shoulder Instability, Western Ontario Rotator Cuff, and Shoulder Instability-Return to Sport after Injury. They performed four physical tests: the glenohumeral rotator isometric strength test, upper quarter Y-balance test, unilateral seated shot put test, and modified Closed Kinetic Chain Upper Extremity Stability Test. The results showed that the female athletes had less shoulder functional abilities than the male athletes (p < 0.001 to p = 0.02). The younger athletes had poorer shoulder stability and upper extremity power than the older athletes (p < 0.001 to p = 0.02), but their glenohumeral muscles were stronger in both internal (p = 0.03) and external (p = 0.005) rotations. All the judo athletes had similar bilateral differences in shoulder functional status, except for judokas who preferred throwing techniques (p = 0.01). Injury history affected self-perceived functional status (p < 0.001), as well as upper extremity muscle capacity and neuromuscular control (p = 0.01 to p = 0.05). This study provides new insight into the shoulder functional status of elite judo athletes, which may aid in the development of sports-specific injury prevention and return-to-sport programmes to reduce the risk of shoulder injury occurrence and recurrence.HighlightsNormalized levels of upper extremity abilities must be sex- and age-specific in prevention programmes.Prevention programmes may focus on muscle bilateral and anteroposterior symmetry.Prevention programmes may include psychological training tailored to the sex of judo athletes.

Intra-cycle analysis of muscle vibration during cycling.

Cyclists are exposed for a long period to continuous vibrations. When a muscle is exposed to vibration, its efficiency decreases, the onset of fatigue occurs sooner, and the comfort of the cyclist is reduced. This study characterised the vastus lateralis (VL) soft tissue vibrations for different input frequencies and different pedalling phases. Ten cyclists were recruited to pedal at 55, 70, 85, and 100 rpm on a vibrating cycle ergometer that induced vibrations at frequencies ranging from 14.4 Hz (55 rpm) to 26.3 Hz (100 rpm). The VL vibration amplitude was quantified with a continuous wavelet transform and expressed as a function of the crank angle. The pedalling cycle was split into four phases (downstroke, backstroke, upstroke, and overstroke) to express the mean vibration amplitude and frequency of each phase. Statistical analysis depicted that VL vibration frequency increased with the pedalling cadence and that the VL was exposed to up to 50% more vibration amplitudes during the downstroke phase at a slow cadence. The increase in the pedal vibration frequency, a higher vibration transmission due to greater normal force on the pedal, and strong activation of the VL during the downstroke phase were discussed to explain these results.

Does neuromuscular fatigue generated by trail running modify foot-ground impact and soft tissue vibrations?

The purpose of the study was to assess the influence of a preceding mountain ultramarathon on the impact between the foot and the ground and the resulting soft tissue vibrations (STV). Two sessions of measurements were performed on 52 trail runners, before and just after mountain trail running races of various distances (from 40 to 171 km). Triaxial accelerometers were used to quantify the foot-ground impact (FGI) and STV of both gastrocnemius medialis (GAS) and vastus lateralis (VL) muscles during level treadmill running at 10 km·h-1. A continuous wavelet transform was used to analyze the acceleration signals in the time-frequency domain, and the maps of coefficients as well as the frequency and damping properties of STV were computed. Fatigue was assessed from isometric maximal voluntary contraction force loss of knee extensors (KE) and plantar flexors (PF) after each race. Statistical nonParametric Mapping and linear mixed models were used to compare the means between the data obtained before and after the races. FGI amplitude and GAS STV were not modified after the race, while VL STV amplitude, frequency and damping significantly decreased whatever the running distance. A significant force loss was observed for the PF (26 ± 14%) and KE (27 ± 16%), but this was not correlated to the changes observed in STV. These results might reveal a protection mechanism of the muscles, indicating that biomechanical and/or physiological adaptations may occur in mountain ultramarathons to limit STV and muscle damage of knee extensors.Trial registration: ClinicalTrials.gov identifier: NCT04025138..

Trail running races with distances from 40 to 171 km induced the same alterations of soft-tissue vibrations. Due to the hilly characteristics of trail running, only the vastus lateralis soft-tissue vibrations were affected by the races.Vastus lateralis vibration amplitude, frequency and damping coefficient were reduced after trail running races. These modifications can arise from a protection mechanism and/or modification in the muscle properties.Neuromuscular fatigue quantified with loss of maximal isometric force production is not predictive of soft-tissue vibration modifications.

Optimal Combination of Femoral Tunnel Orientation in Anterior Cruciate Ligament Reconstruction Using an Inside-out Femoral Technique Combined With an Anterolateral Extra-articular Reconstruction.

BACKGROUND: The optimal orientation of the anterolateral extra-articular reconstruction (ALLR) femoral tunnel to avoid collision with the anterior cruciate ligament reconstruction (ACLR) femoral tunnel is not clearly defined in the literature. PURPOSE: To define the optimal combination of orientations of the ALLR femoral tunnel and the ACLR femoral tunnel using an inside-out technique to minimize risk of collision between these tunnels. STUDY DESIGN: Descriptive laboratory study. METHODS: Three-dimensional reconstruction of magnetic resonance imaging scans of 40 knees after an isolated ACLR with an inside-out femoral technique was used to assess the collision risk between ACLR and virtual ALLR tunnels. The optimal ACLR tunnel orientation was defined as having the safest distance from the ALLR tunnel. A second collision analysis was performed on all patients presenting with an optimal orientation of the ACLR tunnel to then define the optimal ALLR tunnel orientation. The potential for trochlear damage was also studied. A collision risk of 0% to 5% was considered acceptable and referred to as "low risk." RESULTS: The only ALLR tunnel orientation presenting a low risk of collision with the ACLR tunnel was with an axial angle of 40° anteriorly and a coronal angle of 0°. This orientation presented a 48% risk of trochlear damage with the guide wire of the ALLR tunnel. The more posterior the orientation of the ACLR, the larger the distance from the ALLR tunnel. Among the 22 patients presenting with an optimal ACLR tunnel (alpha angle superior to 40°), the ALLR tunnels aimed with 1 of these 3 orientations presented a low risk of tunnel collision and trochlear damage: 40° axial and 10° coronal, 35° axial and 5° coronal, or 30° axial and 0° coronal. CONCLUSION/CLINICAL RELEVANCE: To minimize risk of tunnel collision or trochlear damage when combining an inside-out ACLR with an ALLR, the ACLR tunnel should be performed with a posterior orientation (alpha angle >40°), and the ALLR tunnel should be aimed with 1 of 3 orientations: 40° axial and 10° coronal, 35° axial and 5° coronal, or 30° axial and 0° coronal.

The S-STARTS Test: Validation of a Composite Test for the Assessment of Readiness to Return to Sport After Shoulder Stabilization Surgery.

BACKGROUND: The time elapsed since surgery is the primary criterion for allowing athletes to return to sport after shoulder stabilization surgery using the Latarjet procedure. The objective assessment of shoulder functional status through the return-to-sport continuum demands a scoring instrument that includes psychological and physical dimensions. This study aimed to statistically validate the Shoulder-SanTy Athletic Return To Sport (S-STARTS) score in patients who have undergone primary shoulder stabilization surgery. HYPOTHESIS: The S-STARTS score fulfils the criteria for statistical validation for assessing return-to-sport readiness after shoulder stabilization surgery. STUDY DESIGN: Diagnostic study. LEVEL OF EVIDENCE: Level 4. METHODS: Fifty patients and 50 controls completed the Shoulder Instability-Return to Sport after Injury questionnaire and performed 4 physical performance tests, from which 8 outcome measures were extracted to provide a composite score, named S-STARTS, according to a scoring procedure. The statistical validation of the S-STARTS score was based on construct validity, discriminant validity, sensitivity to change, internal consistency, reliability, agreement, and feasibility. RESULTS: The 8 components of the S-STARTS score provided additional information (0.01 ≤ |r| ≤ 0.59). The S-STARTS score exhibited good reliability (intraclass coefficient of correlation [3,k] = 0.74), no ceiling or floor effects, and high discrimination and sensitivity to change. The S-STARTS score was significantly lower in patients than in controls (13.5 ± 3.8 points vs 16.1 ± 2.7 points, respectively; P < 0.001). A significant increase was reported between 4.5 and 6.5 months postoperatively (12.8 ± 2.3 points vs 17.2 ± 2.4 points, respectively; P < 0.001). CONCLUSIONS: The S-STARTS score meets statistical validation criteria for the assessment of shoulder functional status after shoulder stabilization surgery using the Latarjet procedure. CLINICAL RELEVANCE: Using an S-STARTS score-based assessment to monitor an athlete's progression through the return-to-sport continuum may help clinicians and strength and conditioning coaches in return-to-sport decision-making.

Isokinetic Strength After ACL Reconstruction: Influence of Concomitant Anterolateral Ligament Reconstruction.

BACKGROUND: To reduce the rate of anterior cruciate ligament (ACL) graft rupture, recent surgeries have involved anterolateral ligament reconstruction (ALLR). This reconstruction procedure harvests more knee flexor muscle tendons than isolated ACL reconstruction (ACLR), but its influence on knee muscle strength recovery remains unknown. This study aimed to assess the influence of ALLR with a gracilis graft on the strength of the knee extensor and flexor muscles at 6 months postoperatively. HYPOTHESIS: The additional amount of knee flexor harvest for ALLR would result in impairment in knee flexor muscle strength at 6 months postoperatively. STUDY DESIGN: Retrospective cohort study. LEVEL OF EVIDENCE: Level 2. METHODS: A total of 186 patients were assigned to 2 groups according to the type of surgery: ACL + ALLR (graft: semitendinosus + gracilis, n = 119) or isolated ACLR (graft: semitendinosus, n = 67). The strength of the knee extensor and flexor muscles was assessed using an isokinetic dynamometer at 90, 180, and 240 deg/s for concentric and 30 deg/s for eccentric contractions and compared between groups using analysis of variance statistical parametric mapping. RESULTS: Regardless of the surgery and the muscle, the injured leg produced significantly less strength than the uninjured leg throughout knee flexion and extension from 30° to 90° for each angular velocity (30, 90, 180, and 240 deg/s). However, the knee muscle strength was similar between the ACL + ALLR and ACLR groups. CONCLUSION: The addition of ALLR using the gracilis tendon during ACLR does not alter the muscle recovery observed at 6 months postoperatively. CLINICAL RELEVANCE: Although more knee flexor muscle tendons were harvested in ACL + ALLR, the postoperative strength recovery was similar to that of isolated ACLR.

Intra- and intersession reliability and agreement of the Unilateral Seated Shot-Put Test outcome measures in healthy male athletes.

BACKGROUND: The Unilateral Seated Shot-Put Test (USSPT) consists of pushing an overweight ball as far as possible to assess upper extremity power unilaterally and bilateral symmetry. Literature however reports various body positions and upper limb pushing patterns to perform USSPT, demanding to provide additional guideline to achieve overweight ball push. This study therefore aimed at assessing the reliability and agreement of USSPT outcome measures when pushing an overweight ball in a horizontal direction. METHODS: Twenty-seven healthy male athletes performed two sessions, one week apart, of three unilateral pushes per upper limb using a 3-kg medicine ball, for which the distances were measured. The intraclass correlation coefficient (ICC), standard error of measurement (SEM), minimum detectable change at a 95 % confidence level (MDC95 %) and coefficient of variation (CV) were assessed for the pushing distances based on one, two or three trials per side to produce two outcome measures: the pushing distance per limb and USSPT Limb Symmetry Index (LSI) when dividing pushing distance of the dominant side by that of the non-dominant side. RESULTS: The most reliable pushing distance per limb was obtained when averaging three pushing distances, normalized by body mass with the exponent 0.35. The mean USSPT LSI was 1.09 ± 0.10 for the first session and 1.08 ± 0.10 for the second session, highlighting good reliability and agreement (ICC = 0.82; SEM = 0.045; MDC95 % = 0.124; CV = 5.02 %). CONCLUSIONS: When the overweight ball is pushed in a horizontal direction, averaging the distances of three trials for both the dominant and non-dominant limbs is advised to provide the most reliable USSPT distance per limb and USSPT LSI.

Revisiting the acute effects of resistance exercise on motor imagery ability.

Motor imagery (MI) shares psychological and physiological similarities with the physical practice of the same action. Yet, it remains unclear whether fatigue elicited by exercise impairs MI ability. Fourteen participants performed MI of a self-paced walking sequence of 22 m before and after a resistance exercise eliciting muscle fatigue from upper and lower limbs, selectively. We indexed MI ability using psychometric and behavioral methods. Electromyography of the quadriceps was also recorded during physical practice trials of the walking sequence. For both experimental conditions, we recorded improved temporal congruence between MI and physical practice of the walking sequence (9.89 %, 95 % CI [7.03, 12.75], p < 0.01). Vividness decreased immediately after the fatiguing exercise (6.35 %, 95 % CI [5.18, 7.51], p < 0.05), before rapidly returning to pre-fatigue values during recovery trials. The results challenge the hypothesis of an effect of acute fatigue elicited by a resistance exercise on MI ability, i.e. restricted to MI tasks focusing fatigued effectors. The beneficial effects of fatigue conditions on the psychometric and behavioral indexes of MI ability are discussed in the broader context of psychobiological fatigue models linking perceived exertion with the reallocation of attentional resources. The general perception of fatigue, rather than local muscle fatigue, appeared linked to the acute effects of resistance exercise on MI ability.

Three-Dimensional Upper Body Kinematics and Inter-articular Kinematic Sequence During a Canoe Polo Throw.

Canoe polo is an increasingly popular discipline requiring both kayaking and ball-handling skills. While the kinematics of the upper body during throw has been investigated for several overhead sports, the canoe polo throw has still to be studied. Therefore, the aim of this study is to analyze the canoe polo throw kinematics in terms of angles and inter-articular sequencing to understand its specificity. A secondary aim was to investigate whether adding pelvis mobility has an impact. Nineteen male players of canoe polo were equipped with reflective body markers for the throw analysis. They performed 5 throws with the pelvis fixed and 5 throws with additional pelvic mobility in rotation around a vertical axis. Inverse kinematics was performed with OpenSim providing pelvis, trunk, and glenohumeral rotations. Angular velocities were calculated to build the inter-articular sequences relative to these throws. Statistical parametric mapping was used to assess the effect of pelvis mobility on the throwing kinematics. Similar kinematics patterns as in other overhead sports were observed, however, a different inter-articular sequence was found for the canoe polo throw with a maximal angular velocity occurring sooner for the thorax in axial rotation than for the pelvis in rotation. While the limitation of rotation of the pelvis around a vertical axis has an influence on the pelvis and trunk kinematics, it did not modify the kinematic sequence.

Is Accelerometry an Effective Method to Assess Muscle Vibrations in Comparison to Ultrafast Ultrasonography?

OBJECTIVE: The purpose of this study was to assess whether accelerometry effectively reflects muscle vibrations measured with ultrafast ultrasonography. METHODS: Vibration characteristics initiated on the vastus lateralis muscle by an impactor were compared when assessed with accelerometry and ultrasonography. Continuous wavelet transforms and statistical parametric mapping (SPM) were performed to identify discrepancies in vibration power over time and frequency between the two devices. RESULTS: The SPM analysis revealed that the accelerometer underestimated the muscle vibration power above 50 Hz during the first 0.06 seconds post impact. Furthermore, the accelerometer overestimated the muscle vibration power under 20 Hz, from 0.1 seconds after the impact. Linear regression revealed that the thicker the subcutaneous fat localized under the accelerometer, the more the muscle vibration frequency and damping were underestimated by the accelerometer. CONCLUSION: The skin and the fat tissues acted like a low-pass filter above 50 Hz and oscillated in a less damped manner than the muscle tissue under 20 Hz. SIGNIFICANCE: To eliminate some artifacts caused by the superficial tissues and assess the muscle vibration characteristics with accelerometry, it is suggested to 1) high-pass filter the acceleration signal at a frequency of 20 Hz, under certain conditions, and 2) include participants with less fat thickness. Therefore, the subcutaneous thickness must be systematically quantified under each accelerometer location to clarify the differences between subjects and muscles.

Acquisition and consolidation of sequential footstep movements with physical and motor imagery practice.

Sleep-dependent performance enhancement has been consistently reported after explicit sequential finger learning, even using motor imagery practice (MIP), but whether similar sleep benefits occur after explicit sequential gross motor learning with the lower limbs has been addressed less often. Here, we investigated both acquisition and consolidation processes in an innovative sequential footstep task performed either physically or mentally. Forty-eight healthy young participants were tested before and after physical practice (PP) or MIP on the footstep task, following either a night of sleep (PPsleep and MIPsleep groups) or an equivalent daytime period (PPday and MIPday groups). Results showed that all groups improved motor performance following the acquisition session, albeit the magnitude of enhancement in the MIP groups remained lower relative to the PP groups. Importantly, only the MIPsleep group further improved performance after a night of sleep, while the other groups stabilized their performance after consolidation. Together, these findings demonstrate a sleep-dependent gain in performance after MIP in a sequential motor task with the lower limbs but not after PP. Overall, the present study is of particular importance in the context of motor learning and functional rehabilitation.

The effect of anterolateral ligament reconstruction on knee constraint: A computer model-based simulation study.

BACKGROUND: To determine the influence of anterolateral ligament reconstruction (ALLR) on knee constraint through the analysis of knee abduction (valgus) moment when the knee is subjected to external translational (anterior) or rotational (internal) loads. METHODS: A knee computer model simulated from a three-dimensional computed tomography scan of healthy male was implemented for this study. Three groups were designed: (1) intact knee, (2) combined Anterior Cruciate Ligament (ACL) and Antero-Lateral Complex (ALC) deficient knee, and (3) combined ACL and Antero- lateral Ligament (ALL) reconstructed knee. The reconstructed knee group was subdivided into four groups according to attachment of reconstructed anterolateral ligament to the femoral epicondyle. Each group of simulated knees was placed at 0°, 10°, 20°, 30°, 40° and 50° of knee flexion. For each position an external anterior (drawer) 90-N force or a five-newton meter internal rotation moment was applied to the tibia. The interaction effect between the group of knees and knee flexion angle (0-50°) on knee kinematics and knee abduction moment under external loads was tested. RESULTS: When reconstructed knees were subjected to a 90-N anterior force or a five-newton meter internal rotation moment there was significant reduction in anterior translation and internal rotation compared with deficient knees. Only the ALLR procedure using posterior and proximal femoral attachment sites for graft fixation combined with ACL reconstruction allowed similar mechanical behavior to that observed in the intact knee. CONCLUSIONS: Combined ACL and ALLR using a minimally invasive method in an anatomically reproducible manner prevents excessive anterior translation and internal rotation. Using postero-proximal femoral attachment tunnel for reconstruction of ALL does not produce overconstraint of the lateral tibiofemoral compartment.

Shoulder functional status in rugby union players with and without history of shoulder problems.

OBJECTIVES: To assess the effects of (1) rugby union practice, (2) history of injury managed nonoperatively, and (3) history of injury managed operatively on shoulder functional status in male rugby union players. DESIGN: Cross sectional study. SETTING: Clinical. PARTICIPANTS: 86 male athletes were assigned into four groups: multisport athletes, rugby union players without shoulder problems, with history of shoulder injury managed nonoperatively and with history of shoulder injury managed operatively. MAIN OUTCOME MEASURES: SI-RSI questionnaire, maximal isometric glenohumeral internal and external rotator strength, unilateral seated shot put test, upper quarter Y balance test. RESULTS: Healthy players presented higher internal (p = 0.03) and external (p = 0.04) rotator strength than multisport athletes. History of shoulder injury managed nonoperatively did not impair physical abilities but limited player's psychological readiness (p < 0.001). After 4.5-months, shoulder stabilization surgery impaired maximal muscle strength and upper quarter body stability and mobility (p < 0.001 for all). CONCLUSIONS: The shoulder functional status in rugby union player presented increased glenohumeral rotator strength when compared to non-collision sport athletes. In rugby union players, psychological concerns remained in the long-term after a shoulder injury managed nonoperatively, and psychological and physical readiness seemed not be reached at 4.5 months postoperatively to respond to rugby union practice demand.

Input and Soft-Tissue Vibration Characteristics during Sport-Specific Tasks.

PURPOSE: To assess the influence of sport-specific tasks on the characteristics of input and soft-tissue vibrations. METHODS: Triaxial accelerometers were used to quantify the input (heel cup of the shoe) and soft-tissue vibrations of the gastrocnemius medialis and vastus lateralis muscles during seven sport-specific tasks performed by 10 healthy volunteers. A wavelet analysis was used to analyze the acceleration signals in the time-frequency domain. The energy and frequency of the input and soft-tissue vibrations, as well as the transmission of energy from the input to the muscles and the damping properties of soft tissues, were computed. RESULTS: Different inputs, energy transmissions, and damping properties were found between the various movements. Landings and side cuts induced the greatest input frequency and energy, as well as the greatest soft-tissue vibration energy. These tasks produced up to three times greater energy than in-line running. Positive energy transmission was found for frequencies under 50 Hz and for frequencies up to 90 Hz for some movements, indicating a possible change in the natural frequency of vibration within muscle. Only small differences in damping properties were found, which may indicate that the attenuation of the vibration was not the priority during these tasks. CONCLUSIONS: Athletes are subject to greater energy impacts and vibrations during some sport-specific tasks compared with running. It may be useful to decrease such input/vibration energy via the usage of footwear or compression tools to limit their potential deleterious effects on the musculoskeletal system. It is, therefore, recommended to quantify and control the number of impacts induced by the different sport-specific tasks.

Age-related differences of inter-joint coordination in elderly during squat jumping.

BACKGROUND: Explosive movement requires that the individual exerts force and power with appropriate magnitude and timing. These coordination aspects have received less attention despite being a basic prerequisite for daily mobility and physical autonomy, especially in older people. Therefore, the purpose of this study is to characterize the effect of age on inter-joint coordination during explosive movement. METHODS: Twenty-one elderly and twenty young participants performed three maximal vertical jumps, while kinematics were recorded throughout each squat jump. Inter-joint coordination and coordination variability were calculated for selected sagittal hip-knee, knee-ankle, and hip-ankle joint couplings using the continuous relative phase method. RESULTS: The young participants produced significantly greater jump height performance (0.36 ± 0.07 m vs. 0.12 ± 0.04 m, p < 0.001). The mean absolute continuous relative phase for ankle-knee and knee-hip joint couplings were significantly greater for the elderly in comparison to the young group (p < 0.01 for the both). No significant differences between senior and young participants in the mean absolute continuous relative phase for ankle-hip joint couplings (p = 0.25) was observed. However, there was significantly more variability in inter-joint coordination in the elderly marked by greater continuous relative phase variabilities in ankle-knee, ankle-hip and knee-hip joint couplings (p < 0.001) than those observed in young adults. CONCLUSION: In this study, seniors demonstrated proximodistal inter-joint coordination but with different delays in the pattern of inter-joint coordination during squat jumps compared to young adults. In addition, a higher continuous relative phase variability in the elderly may be needed to improve stability or compensate for strength deficits in jump achievement.