The modified Star Excursion Balance Test (mSEBT) is a valid, low-cost, and easily implemented screening tool in clinical practice recommended for assessing dynamic postural control in athletes. ...Previous studies evidenced that poorer performance on the mSEBT predicts an increased risk of injury in several sports. The performance of the mSEBT depends on the contribution of various body segments and constructs of physical function to reach maximum distance in the anterior, posteromedial, and posterolateral directions. Understanding the relationship between mSEBT performance, distal and proximal factors in the kinetic chain and other constructs of physical function in soccer athletes can contribute to a more assertive assessment in clinical practice, since soccer athletes with dynamic balance deficient are more likely to sustain a lower limb injury.
To verify if hip and foot/ankle musculoskeletal factors predicts the performance of the modified Star Excursion Balance Test (mSEBT) in male youth soccer athletes.
In this cross-sectional study, 108 athletes (18.04 ± 0.14 years, 72.86 ± 0.76 kg, 1.78 ± 0.7 m) in categories Under-17 and Under-20 from a professional soccer club in Brazil were assessed during the preseason assessment. The assessment included the following tests: shank-forefoot alignment (SFA), passive hip IR ROM, hamstring flexibility (HF), dorsiflexion range of motion (ROM), Single Leg Hamstring Bridge (SLHB), and the performance of the modified Star Excursion Balance Test (mSEBT). Multiple linear regression analysis was performed to identify if the foot/ankle musculoskeletal factors could explain the performance of the mSEBT.
Regression analyses revealed that shank-forefoot alignment and ankle dorsiflexion ROM predicted the performance of the mSEBT (P < 0.05). In model 1, SFA explained 9% of the mSEBT performance (F = 10.19; r = 0.3; r2 = 0.9; p = 0.002). The inclusion of the ankle dorsiflexion ROM in model 2 explained 16% of the total variance of the mSEBT (F = 8.54; r = 0.4; r2 = 0.16; p = 0.004).
The ankle dorsiflexion ROM and shank-forefoot alignment explained 16% of the performance of the mSEBT in male youth soccer athletes. These results suggest that the ankle dorsiflexion ROM and shank-forefoot alignment contribute to test performance and the physiotherapist must assess these factors.
The results of this study suggest that considering the influence of distal musculoskeletal factors of the kinetic chain on dynamic postural control and the association of the ankle dorsiflexion ROM and the shank-forefoot alignment with the performance of the mSEBT in youth soccer athletes. Athletes with a lower performance in the test should be assessed to verify the shank-forefoot alignment and the ankle dorsiflexion ROM. In addition, the improvement of the ankle mobility can be considered a good intervention in the implementation of prevention programs.
This study was designed to analyze the effects of type of activity and cruciate ligament resection on knee kinematics and ligament balance after total knee arthroplasty (TKA), and to determine if ...intraoperative passive kinematics are associated with active kinematics. Fresh‐frozen human cadaveric knees were examined. The knees were mounted on a quadriceps‐driven simulator. Cruciate‐retaining (CR‐TKA) and posterior‐substituting (PS‐TKA) TKA was performed using a contemporary knee system. Active flexion (closed‐kinetic chain CKC and open‐kinetic‐chain OKC) and passive flexion were analyzed by recording the knee kinematics using a specifically developed application of an imageless navigation system. An electronic ligament balancer was used to measure the tibiofemoral gap under constant distraction pressure. The femur rotated externally relative to the tibia during passive and active CKC flexion. The femur translated anteriorly from 10° to 50° of flexion after TKA. Beyond 50° of flexion, the femur translated posteriorly in all surgical conditions. The femoral location during active CKC flexion was posterior relative to that during active OKC. Femoral rotation and translation during passive knee flexion correlated significantly with that during active knee flexion. Posterior tilt of the electronic ligament balancer was greater with CR‐TKA than with PS‐TKA and correlated significantly with the anteroposterior position of the femur. Statement of Clinical Significance: Intraoperative knee kinematics measured by computer‐assisted navigation and intraoperative ligament balance have the potential to predict postoperative knee kinematics.
Overuse injuries are often caused by pronated foot and the associated abnormal lower-extremity kinematics during dynamic activities. Various patterns of foot kinematics are observed among individuals ...with pronated feet during dynamic activities, resulting in different dynamic kinematics of the proximal joint. This study aimed to identify the foot kinematic patterns during gait among individuals with pronated feet and evaluate the relationship between these foot kinematic patterns and the hip and knee kinematics. A three-dimensional motion capture system was used to collect data regarding the foot, knee, and hip kinematics during the stance phase of gait of 42 individuals with pronated feet. A hierarchical cluster analysis method was used to identify the optimal number of clusters based on the foot kinematics, including navicular height (NH) at initial contact and dynamic navicular drop (DND). The differences in the cluster and demographic variables were examined. One-dimensional statistical parametric mapping was used to evaluate the differences in the time histories of the NH, knee, and hip kinematics during the stance phase. Three subgroups were identified on the basis of the NH and DND: Cluster 1, moderate NH at initial contact and larger DND; Cluster 2, highest NH at initial contact and smaller DND; and Cluster 3, lowest NH at initial contact and smaller DND. The hip adduction angle of Cluster 1 was significantly higher than that of Cluster 3 from the 0% to 51% stance phases. Further longitudinal studies are needed to clarify the relationship between identified subgroups and the development of overuse injuries.
Aging causes changes in stance control and muscle function. However, strength exercises can mitigate these negative effects. Intervention practices are classified into open kinetic chain (OKC) and ...closed kinetic chain (CKC), but it is unclear whether there are differences between them regarding muscle power and balance in the older people. Thus, this study aimed to investigate the acute effect of an intervention in OKC and CKC on stance control and muscle power in the older people.
This study is a randomized clinical trial. A total of 29 older people participated in this study, divided into 3 groups: control group (CG) (n = 9), open kinetic chain group (OKCG) (n = 10), and closed kinetic chain group (CKCG) (n = 10). Stance control was evaluated on a force platform under bipedal, semi-tandem, and unipedal support conditions. Muscle power assessed based on the time to perform the sit-to-stand test (STS). The acute intervention in OKC and CKC consisted of 2 exercises for each intervention group.
There was no difference between acute interventions in OKC and CKC on stance control and muscle power. The time in STS was shorter in the CKCG compared to the CG. The largest oscillations of the center of pressure (COP) were found in the unipedal stance condition.
An acute intervention in OKC and CKC did not differentiate stance balance and muscle power in the older people. However, CKC exercises are more effective for functional tasks than OKC exercises. The greater complexity of the task (unipedal support) causes greater stance oscillations in the older people.
•In-vivo tibiofemoral kinematics during box squat (BS) and seated knee extension (SKE) exercises under different loading was compared by dual fluoroscopic imaging.•BS shows less medial tibial ...translation and more stability in IE rotation and ML translation than both loaded/unloaded SKE.•Tibial AP translation is similar between BS and SKE, but tibia translates more anteriorly during loaded SKE than unloaded during mid-flexion.•ACL may safer and have less stretching during BS than SKE, and during unloaded SKE than loaded.
A rehabilitation program after anterior cruciate ligament reconstruction is of great importance to obtain a satisfactory prognosis after surgery. However, there is still an onging debate over whether closed kinetic chain or open kinetic chain exercises should be chosen. Our study was designed to compare the in vivo tibiofemoral kinematics during closed kinetic chain and open kinetic chain exercises.
Eighteen healthy volunteers were asked to perform box squat and unloaded/10 kg-loaded seated knee extension. In vivo 3-dimensional analysis of tibiofemoral kinematics of different motions were determined using a dual fluoroscopic imaging system.
The study found significantly more tibial anterior displacement during loaded seated knee extension than during unloaded seated knee extension from 25°–50° of knee flexion (p ≤ 0.031). The knees exhibited significantly more internal tibial rotation and lateral tibial translation during the box squat than both seated knee extensions during mid-flexion. In addition, the knees showed less internal-external (IE) range of motion (ROM) from 20°– 75° of flexion (p < 0.001) and medial-lateral (ML) ROM from 75° to full extension (p ≤ 0.006) during box squat than both extensions. This knowledge may help optimize rehabilitation plans for patients post ACL reconstruction.
Context:
Anterior cruciate ligament (ACL) reconstruction (ACLR) and postoperative rehabilitation continues to be a multidisciplinary focus in both research and clinical environments. Recent research ...on ACLR warrants a reexamination of clinicians’ current rehabilitation practices to optimize the strikingly variable clinical outcomes after ACLR and return to sport. The purpose of the article and updated guidelines is to use contemporary evidence to systematically revisit our practice guidelines and validate our clinical milestones with data from our university-based practice.
Evidence Acquisition:
Using the PubMed search engine, articles that reported on ACLR rehabilitation and protocols, guidelines, graft type, healing and strain, return to sport, psychological considerations, and secondary injury prevention published from 1979 to 2020 were identified using the search terms ACLR protocols, guidelines, ACLR rehabilitation, ACL graft, ACL open kinetic chain (OKC) exercise and closed kinetic chain (CKC) exercise, ACLR return to sport, ACLR psychological factors, and ACL injury prevention.
Study Design:
Clinical review.
Level of Evidence:
Level 5.
Results:
Clinical milestones after ACLR were validated using clinical data collected from 2013 to 2017 at a university-based practice. Variables including knee joint range of motion, effusion, Knee Outcome Survey–Activities of Daily Living Scale, and quadriceps strength index were tracked throughout rehabilitation and analyzed to help inform an updated ACLR rehabilitation guideline.
Conclusion:
Incorporating the latest research, combined with direct clinical data, provides a current, realistic, and clinically benchmarked strategy for ACLR rehabilitation. Commonly held clinical beliefs regarding rehabilitation after ACL injury must be challenged by the latest research to improve patient outcomes and decrease the risk of reinjury. Key updates to the practice guidelines include the use of frequent and accurate quadriceps strength testing, delayed return-to-sport timeline, immediate use of open kinetic chain exercise, criterion-based progressions for running, sprinting, plyometrics, agility, cutting/pivoting, return to competition, and the inclusion of a secondary prevention program after return to sport.
Strength of Recommendation Taxonomy (SORT):
B.
Trampoline bounces are performed on a bed of a jumping surface that is stretched over the trampoline apparatus. The jumping motion is divided into a descent phase, i.e., from the landing to the ...maximum depth, and an ascent phase, from the maximum depth to the takeoff. Most studies on muscle activity during jumping have investigated muscle activity during the same phase between groups or between landing and release; however, no studies have investigated muscle activity between phases. Therefore, this study aimed to investigate muscle activity during the descent and ascent phases and obtain basic data on the jumping motion. For the trials, participants were instructed to perform 15 consecutive jumps on the trampoline bed from a standing still position, as high as possible, straight and straight up in the center of the trampoline bed. The muscle activities of the rectus femoris, tibialis anterior, and lateral gastrocnemius revealed significant increases and larger effect sizes in the descent phase than in the ascent phase (p < 0.01). The muscle activities of the sternocleidomastoid, trapezius, and biceps femoris demonstrated significant increases and medium effect sizes in the descent phase in contrast to the ascent phase (p < 0.01). Pushing down the bed by the muscular activity of the lower extremities is most pursued in the descent phase. Then, participants maintain a straight vertical posture for the body to receive the rebound force from the maximum depth of the bed. This suggests that the sternocleidomastoid and trapezius muscles were significantly active in controlling the head position. A high jump is achieved by pushing the bed down for a deep descent and maintaining a straight posture at the maximum depth. The elastic bed is similar to an Open Kinetic Chain in the descent phase because the load incrementally increases, and to a Closed Kinetic Chain in the ascent phase because the load begins at the maximum depth of the bed. Separating the elements of the jumping motion required in the descent and ascent phases is important in athletic training
Single leg squat (SLS) is an important motion commonly observed in sports. Excessive dynamic knee valgus (DKV) during SLS may increase non-contact knee injury risks particularly in physically active ...females. As muscular strength plays crucial role in controlling DKV, the present study aims to evaluate the correlation between hip strength and knee frontal plane angle during SLS among females with and without excessive DKV.
Thirty-four volunteers were allocated to the valgus (n = 17) and non-valgus (n = 17) groups. Their motions during SLS at 45° and 60° knee flexion were captured and analyzed using three-dimensional motion analysis system. Isokinetic hip strength was examined at 180°/s in flexion, extension, abduction, and adduction for both legs. Pearson's correlation test was computed to evaluate the relationship between hip strength and knee angle during SLS.
Non-dominant hip extensor strength (r = −0.56, p = 0.02) and dominant hip adductor strength (r = −0.51, p = 0.04) were significantly related to the knee frontal plane angle during 45° SLS among those without DKV. Meanwhile, those with DKV showed a significant relationship between the knee frontal plane angle for both legs and non-dominant hip abductor strength during 60° SLS.
Both groups demonstrated the relationship of hip strength on knee frontal plane angle during SLS, whereby increased hip strength may minimize excessive DKV. Those with excessive DKV should train to strengthen their hip abductor to reduce knee valgus particularly during deep squats.
•Both women with and without DKV demonstrated the influence of hip strength on knee angle during SLS.•Women with and without DKV emphasize on different muscle groups at different squat depths.•In deep squats, training should focus on increasing the hip abductors strength.
Conflicting results have been reported on whether closed kinetic chain exercises (such as a leg press) may induce more balanced activation of vastus medialis (VM) and lateralis (VL) muscles compared ...with open kinetic chain exercise (such as pure knee extension). This study aimed to 1) compare between-vasti motor unit activity and 2) analyze the combined motor unit behavior from both muscles between open and closed kinetic chain exercises. Thirteen participants (four women, mean ± SD age: 27 ± 5 yr) performed isometric knee extension and leg press at 10, 30, 50, 70% of the maximum voluntary torque. High density surface EMG signals were recorded from the VM and VL and motor unit firings were automatically identified by convolutive blind source separation. We estimated the total synaptic input received by the two muscles by analyzing the difference in discharge rate from recruitment to target torque for motor units matched by recruitment threshold. When controlling for recruitment threshold and discharge rate at recruitment, the motor unit discharge rates were higher for knee extension compared with the leg press exercise at 50% estimate = 1.2 pulses per second (pps), standard error (SE) = 0.3 pps,
= 0.0138 and 70% (estimate = 2.0 pps, SE = 0.3 pps,
= 0.0001) of maximal torque. However, no difference between the vasti muscles were detected in both exercises. The estimates of synaptic input to the muscles confirmed these results. In conclusion, the estimated synaptic input received by VM and VL was similar within and across exercises. However, both muscles had higher firing rates and estimated synaptic input at the highest torque levels during knee extension. Taken together, the results show that knee-extension is more suitable than leg-press exercise at increasing the concurrent activation of the vasti muscles.
There is a significant debate on whether open kinetic chain, single-joint knee extension exercise can influence the individual and combined activity of the vasti muscles compared with closed kinetic chain, multijoint leg press exercise. Here we show that attempting to change the contribution of either the vastus medialis or vastus lateralis via different forms of exercise does not seem to be a viable strategy. However, the adoption of open kinetic chain knee extension induces greater discharge rate and estimated synaptic input to both vasti muscles compared with the leg press.
Mechanical energy is known to be transferred between a body segment and a joint. However, the transformation of this energy has not been classified. By focusing on the racket-holding arm during a ...tennis serve, the present study examined the transformation between translational and rotational energies due to the joint force, and investigated the kinetic chain from the viewpoint of energetics. Twenty-two tennis players were asked to perform flat services to the deuce side (i.e., the receiver’s right side), and the three-dimensional coordinates of reflective markers attached to each player and racket were collected with a motion capture system. The mechanical power acting on each segment and the mechanical energy generated/absorbed by each joint were divided into the following components: (1) STP = the time rate of change in the rotational energy of a segment due to the joint torque, (2) JTP = the generation/absorption of rotational energy due to the joint torque, (3) JFPt = the time rate of change in the translational energy of a segment due to the joint force, and (4) JFPr = the time rate of change in the rotational energy of a segment due to the moment of the joint force. The findings are summarized below.1. The proposed method can divide the power acting on the segment due to joint force into the translational component (JFPt) and the rotational component (JFPr).2. The racket-holding arm mainly acquires mechanical energy as translational energy with decreasing rotational energy of the upper trunk (around right-leftward rotation).3. The main role of the shoulder joint is not to generate rotational energy but to change the energy form (from translational energy to rotational energy).4. The main role of the phase before most of the shoulder external rotation is to store the translational energy in the racket-holding arm.5. The main role of the phase after most of the shoulder external rotation is to transfer the translational and rotational energies to the racket.6. The proposed method can quantify not only the generation/absorption and transmission of mechanical energy but also the transformation of the energy form. Therefore, this method may produce new findings that have not yet been clarified.
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