Knee Biomechanics During Neurocognitively Challenged Drop Landings in Male Elite Soccer Players with Anterior Cruciate Ligament Reconstruction.

BACKGROUND: Reactive decision-making during athletic movement has been demonstrated to evoke unfavorable biomechanics associated with anterior cruciate ligament (ACL) rupture. However, the current evidence is based on assessments of healthy individuals. We aimed to investigate unplanned jump landing kinetics and knee kinematics in ACL-reconstructed (ACLR) and non-injured athletes. METHODS: A total of 30 male professional soccer players (n = 15 ACLR after return to play, n = 15 matched controls) performed six drop landings onto a force plate. As a neurocognitive challenge requiring decision-making, a diode flashing in randomly selected colors indicated the requested landing location. Knee joint kinematics (flexion, valgus and tibial rotation angles) assessed with a 10-camera motion capture system, vertical ground reaction force (vGRF), time to stabilization (TTS) and length of the center of pressure (COP) trace (all analyzed from force plate data) were calculated. Cognitive function was assessed using the CNS Vital Signs battery. RESULTS: The ACLR group produced lower knee flexion angles than the control group (median [interquartile range] 50.00° [6.60] vs. 55.20° [4.45], p = .02). In addition, path length of the center of pressure (379 mm [56.20] vs. 344 mm [37.00], p = .04) and ground reaction force (3.21 N/kg [0.66] vs. 2.87 N/kg [0.48], p = .01) were higher for the ACLR group. No differences were found for knee valgus (p = .96), tibial rotation (p = .83) and TTS (p = .82). ACLR participants scored lower for reaction time (p = .02) and processing speed (p = .01). Unfavorable knee biomechanics were more often related to cognitive function in the ACLR group than in the control group (p < .05). CONCLUSIONS: Impaired reactive decision-making during athletic movement may contribute to the high re-injury risk in individuals with ACLR. Prospective studies confirming potential cause-effect relationships are warranted.

Effects of FIFA 11 + warm-up program on kinematics and proprioception in adolescent soccer players: a parallel­group randomized control trial.

This study aimed to compare the effects of 8 weeks 11 + warm-up injury prevention program on kinematics and proprioception in adolescent male and female soccer players. Forty adolescent soccer players (20 males, 20 females) aged between 14-16 years old were randomly assigned into four groups. The experimental group performed the 11 + program for 8 weeks and the control group did their warm-up program. The kinematic variable in a cutting maneuver was measured using VICON motion analysis and ankle and knees' proprioception by joint position sense (JPS) was measured using a digital inclinometer. For kinematic variables only significant differences in knee valgus among females 11 + compared with female and male control groups were found (P < 0.05). Moreover, there were significant improvements in joint position sense variables in 11 + groups compared to control groups (P < 0.05). In conclusion, the 11 + program was proven to be a useful warm-up protocol in improving knee valgus and JPS among female and male adolescent soccer players. We suggest adding more training elements to the 11 + program that aimed to enhance the proper alignment of lower extremities which may consequently improve joint kinematics.

Analysis of change of direction performance with dominant and non-dominant leg using linear and nonlinear approaches.

This study was aimed to analyse the lower limb kinematics during the change of direction (COD) performance with the dominant (DL) and non-dominant (NDL) leg using linear (traditional kinematics) and nonlinear (Self Organising Map-based cluster analysis) approaches. Three 5-0-5 COD performances with the DL and three with the NDL were performed by 23 (aged 21.6 ± 2.3 years) collegiate athletes. No significant difference was observed between the COD duration, and approach speed of DL and NDL. Significantly greater ankle abductions, knee and hip external rotations were identified in COD with DL, compared to NDL (p < .001, d > 0.8). Self Organising Maps portrayed a completely different coordination pattern profile during change of direction performance with the DL and NDL. The cluster analysis illustrated similar inter-individual coordination patterning when participants turned with their DL or NDL. No visible relationship was observed in the cluster analysis of the lower limb joint angles and angular velocities. Outcomes of this study portrayed that coordination patterning (combination of joint angles and the rate of change of angles) could portray the movement patterning differences in different tasks, while a sole investigation on the joint angles or angular velocities may not reveal the underlying mechanisms of movement patterning.

Using Metabolomics to Differentiate Player Positions in Elite Male Basketball Games: A Pilot Study.

Purpose: The current study compared metabolic profiles and movement patterns between different player positions and explored relationships between indicators of internal and external loads during elite male basketball games. Methods: Five main players from 14 basketball teams (n = 70) were selected as subjects and defined as backcourt (positions 1-3) or frontcourt (positions 4-5) players. Video-based time motion analysis (VBTMA) was performed based on players' individual maximal speeds. Movements were classified into high and low intensity running with and without ball, high and low intensity shuffling, static effort and jumps. Saliva samples were collected before and after 40-min basketball games with metabolomics data being analyzed by multivariate statistics. Independent t-tests were used to compare VBTMA. Results: Frequency, duration, and distance of high and low intensity running and -shuffling were higher in backcourt players, whereas static effort duration and frequency as well as jump frequency were higher in frontcourt players (all p ≤ 0.05). The levels of taurine, succinic acid, citric acid, pyruvate, glycerol, acetoacetic acid, acetone, and hypoxanthine were higher in backcourt players, while lactate, alanine, 3-methylhistidine were higher and methionine was lower in frontcourt players (all p < 0.05). High intensity running with ball was significantly associated by acetylecholine, hopoxanthine, histidine, lactic acid and leucine in backcourt players (p < 0.05). Conclusion: We demonstrate different metabolic profiles of backcourt and frontcourt players during elite male basketball games; while aerobic metabolic changes are more present in backcourt players, frontcourt players showed lager changes in anaerobic metabolic pathways due to more static movements.

Metabolic load comparison between the quarters of a game in elite male basketball players using sport metabolomics.

Purpose: A basketball match is characterized by intermittent high-intensity activities, thereby relying extensively on both aerobic and anaerobic metabolic pathways. Here, we aimed to compare the metabolic fluctuations between the four 10-min quarters of high-level basketball games using metabolomics analyses. Methods: 70 male basketball players with at least 3 years of experience in the Iran national top-league participated. Before and after each quarter, saliva samples were taken for subsequent untargeted metabolomics analyses, where Principal component analysis (PCA) and Partial least squares-discriminant analysis (PLS-DA) were employed for statistical analysis. Results: Quarters 1 and 3 showed similar metabolic profiles, with increased levels of ATP turnover (higher Lactate, Pyruvate, Succinic Acid, Citric Cid, Glucose and Hypoxanthine), indicating more reliance on anaerobic energy systems than quarters 2 and 4. In comparison, quarters 2 and 4 showed a reduction in Valine and Lucien and an increase in Alanine, Glycerol, AcetoAcetic Acid, Acetone, Succinic Acid, Citric Acid, Acetate and Taurine that was not present in quarters 1 and 3, indicating greater reliance of aerobic energy contribution, fat metabolism and gluconeogenesis. Conclusion: Our data demonstrate that the higher intensity of movements in the first quarter, where players are more rested, induce an increase in anaerobic energy contribution. This seems to be the case also for the third quarter that follows 15 min of rest, whereas the accumulated fatigue and reduction of high-intensity movements in the second and fourth quarters also reduces the speed of energy production and players thereby utilize more aerobic energy.

Review of sport-induced groin injuries.

CONTEXT: Groin injuries are among the most common injuries co-existing with sports. The aim of this review was to outline the epidemiology and identify risk factors, as well as examine preventative and interventional measures for reducing the occurrence of this form of injury among athletes. EVIDENCE ACQUISITION: An electronic, systematic search for relevant keywords, either separately or in combination was sought in the academic scientific databases. RESULTS: Groin injuries, acute or chronic, consist of a high percentage of injuries that manifest with pain. Despite the specific tendency for injury among some sports, such injuries make up 2-5% of sport-induced injuries. There are few available reports on lower limb injuries, especially groin injuries, in Iran. Numerous factors predispose to groin injuries. A lengthy list of preventive/ treatment measures, from preliminary to sophisticated, have been proposed. CONCLUSIONS: Although using a programmed strategy designed to decrease the risk of groin injuries by taking a strategic approach to exercise may alleviate complications, in some cases the chronic nature of the injury may threaten the professional life of the athlete. More research is required to plan suitable programs for reducing the risk of this type of injury in athletes.

Effects of mass and momentum of inertia alternation on individual muscle forces during swing phase of transtibial amputee gait.

A computer simulation was carried out to investigate the forces of lower extremity muscles in the swing phase of a transtibial amputee gait. With each muscle as an ideal force generator, the lower extremity was simulated as a two-degrees of freedom linkage with the hip and knee as its joints. Kinematic data of hip and knee joints were recorded by a motion analysis system. Through a static optimization approach, the forces exerted by muscles were determined so that recorded hip and knee joint angles were produced. Simulation results showed that when the mass of prosthetic foot is increased, muscle forces increase, too. This result is in accord with experimental and theoretical studies that reported an increase in leg mass lead to higher electromyography activity of muscles, and energetic of walking. However, since prosthetic foot moment of inertia is smaller than that of thigh and prosthetic shank, its alternation does not have noticeable effect on muscle forces.