Global Navigation Satellite Systems (GNSS) offer precise movement analyses based on distance and speed in open-water sports. Despite the influence of swimming in triathlon, its performance analysis remains underdeveloped due to methodological limitations in capturing continuous data in aquatic environments. This review aimed to: (1) systematically analyse and compare the sensor-based technologies applied to open-water movement analysis, and (2) propose a framework for continuous GNSS-based assessment of triathlon swim performance. A systematic search was conducted prior to the 14 August 2025 across four databases (Web of Science, SPORTDiscus, PubMed, and SPONET). Studies were eligible if they analysed open-water sports using GNSS-based technologies for continuous movement or performance analysis. Studies limited to indoor swimming, inertial sensors, or non-sporting applications were excluded. Methodological quality and potential sources of bias were evaluated using a custom scheme based on GNSS reporting guidelines, as methodological heterogeneity precluded the application of standardised tools. Following screening and eligibility assessment, articles were analysed qualitatively. In total, 20 articles were included and focused on surfing, sailing, water skiing, windsurfing, kitesurfing, stand-up paddling (SUP), and swimming. Most studies focused on board- and sail-based sports, employed sampling frequencies between 1 and 15 Hz, and demonstrated substantial variability in device specifications and reporting quality. Different sensors and GNSS-derived variables were central to discipline-specific performance analysis. The strength of evidence is limited by the heterogeneous methodologies, and variable reporting quality. The proposed framework provides methodological guidance for implementing high-resolution GNSS-based monitoring in triathlon swimming to improve pacing analysis and race strategy development.

The impact of orthostatic regulation during exercise, particularly resistance training, is not fully understood. This study investigates the acute cardiopulmonary responses of intensity-matched resistance exercises, targeting similar muscle groups but performed in different body positions in young trained females. Fourteen healthy females (21.6 ± 2.0 years) performed a 3-repetition Maximum test (3-RM) for the squat movement in the Smith machine (SM) and the leg press (LP). During two subsequent visits, they randomly completed two training sessions in SM and LP (two sets of ten repetitions at 50% 3-RM). Blood pressure (vascular unloading technique) and cardiopulmonary parameters (impedance cardiography, spirometry) were measured continuously. At baseline, there was a significant difference in heart rate and stroke volume between the SM and LP conditions. During training sessions, the SM condition showed higher ground reaction force (986.9 ± 93.3 vs. 811.2 ± 71.6 N; p < .01), systolic blood pressure (156 ± 15 vs. 141 ± 10 mmHg; p < .01), diastolic blood pressure (111 ± 11 vs. 96 ± 8 mmHg; p < .01), HR (123 ± 11 vs. 97 ± 7 bpm; p < .01), and oxygen uptake (901 ± 104 vs. 623 ± 65 ml/min; p < .01) compared to the LP condition. Total peripheral resistance (TPR) was similar. Significant different post-exercise changes could be detected in mean arterial pressure (-20.9 ± 9.9 vs. 3.3 ± 11.0 mmHg; p < .01) and TPR (-2.3 ± 1.7 vs. 0.7 ± 1.7 mmHg⋅ l⋅min-1; p < .01). Squats in the SM require greater cardiovascular and pulmonary effort than matched exercising in LP due to orthostatic stress and higher muscle activation. Conversely, the risk of blood pressure peaks is much lower with LP. Future analysis should focus on the effects of body position on patient responses.

IntroductionTo enhance release velocity during competition, javelin throwers incorporate implements of varying mass into their training regimens. Previous research has demonstrated that, although velocity contributes quadratically to the computation of kinetic energy, heavier implements generate substantially greater kinetic energy at the moment of release, despite markedly lower release velocities. The primary objective of the present investigation was to analyze energy transfer within the throwing arm to gain deeper insight into the biomechanical mechanisms underlying the use of implements with different masses.MethodsThe three-dimensional coordinates of 16 reflective markers were recorded for 6 athletes during throws using 6 different implement masses, using 12 infrared cameras. Based on this kinematic data, segmental energy transfer was estimated via inverse dynamics using a multi-body modeling approach. Subsequent comparisons were conducted using nonlinear temporal registration and statistical non-parametric mapping.ResultsThe results indicate that energy flow at the shoulder joint remains largely consistent across implements of varying mass. However, significant differences in energy transfer were observed at the more distal joints.DiscussionThe findings suggest that the increased kinetic energy observed with heavier implements arises from an internal redistribution of energy within the throwing arm, rather than from greater overall energy input. Consequently, improvements in release velocity associated with lighter or heavier implements are likely attributable to mechanisms other than modifications in energy flow dynamics.

Javelin throwers cannot safely throw with a long approach run often per training session. Therefore, implements of different shapes and masses are thrown from short run-ups to emulate the demands of achieving high throwing distances. This study examined the effects of different implements, thrown from various approaches, on the kinematics and kinetics of the throwing arm. The throwing motions of 6 athletes, each throwing 6 different implements were recorded using 12 infrared cameras. Kinematics and kinetics of the shoulder and elbow joints were calculated and statistically compared. The results show that lighter implement throws achieved higher release speeds, while heavier implements required greater work to be done on them. We identified significant differences for the shoulder external rotation angle (P < .001), the shoulder internal rotation (P = .040), and elbow extension (P = .003) angular velocities and the torques of the shoulder internal rotation (P = .006), horizontal flexion (P = .004), and the elbow varus (P = .008). It can be concluded that throws with balls of different masses have different angular velocities and joint torques, and therefore can be used to train speed and strength aspects of the javelin throw while using lower run-up speeds.

Purpose:This study explores the potential of Instrumented gait analysis (IGA) as a non-invasive tool for monitoring rehabilitation in pediatric patients with anterior cruciate ligament (ACL) injuries. Current clinical assessments, such as physical exams and X-rays, have limitations in evaluating dynamic knee alignment and loading. IGA may offer a more precise method to track rehabilitation progress and detect altered gait biomechanics following ACL reconstruction (ACLR). We hypothesize that IGA can provide insights into differences in frontal knee alignment and mechanical loading between static and dynamic conditions in pediatric patients following ACLR. Methods:IGA was conducted on 18 patients (mean age: 15 ± 2 years) at 3 and 12 months following ACLR, and seven conservatively treated patients (mean age: 12 ± 3) at 12 months post-injury. Retroreflective markers were placed using the CAST lower body model. The gait was recorded in 3D using 12 infrared and two video cameras. Ground reaction forces were measured with force plates. Frontal knee alignment was assessed from kinematic data at four gait events: double-limb stance, initial contact, loading response, and mid-stance, identified by C-Motion Visual3D Professional. Frontal knee joint moments were calculated based on inverse kinematic and dynamic in Newton-meters per kilogram (Nm/kg) at the specified gait events. Repeated-measures ANOVA was used to compare frontal knee alignment between static and dynamic conditions, while paired t-tests assessed differences between injured and uninjured extremities. Results:In the surgical group, a significant increase in body height occurred between 3 and 12 months (p = 0.001) without notable changes in the static or dynamic frontal axis (p > 0.05). At 12 months post-surgery, mean frontal knee alignment differed significantly between gait events (p < 0.001), showing a transition from valgus during stance to a nearly neutral axis during loading response. A significant difference was observed at initial contact, where the affected leg remained in greater valgus than the unaffected side (p = 0.026). Joint moments showed no significant differences between the healthy and affected sides (p > 0.05). No significant differences were found between the surgical and conservative groups. Conclusions:The findings of this study suggest that IGA can detect dynamic alignment deviations, supporting its potential as a complementary tool for monitoring knee function following pediatric ACL injuries. The absence of significant alignment changes over time indicates a low risk of surgery-induced growth plate injury. While IGA may help identify alignment-related risk factors for re-rupture, its ability to accurately predict graft insufficiency remains unclear. Level of Evidence:Level II, prospective cohort study.

The aims of this study were 1) to propose a simple two-dimensional (2D) video-based method to measure segment lengths in the clean and jerk during weightlifting competitions, and 2) to check concurrent validity and test-retest reliability compared to 3D video-based measurements. In the first part of the study, key body positions for the assessment of segment lengths via 2D measurement method were determined. In the second part, concurrent validity was verified, comparing the 2D segment length measurements to 3D measurements. In the third part, the test-retest reliability of the 2D approach was investigated. In the clean and in the jerk, the lift-off/start position and the position of maximum barbell velocity displayed a minimised offset between 'real' 3D segment lengths and 2D projections of the segment lengths. For the concurrent validity assessment, the overall random measurement error was 4.3% with concordance correlation coefficients ranging from 0.64 to 0.88. The standard error of measurement in the test-retest procedure was 2.4% on average with intraclass correlation coefficients ranging from 0.85 to 0.96. The proposed 2D video-based approach to measure body segment lengths during weightlifting exercises is proven to be a valid and reliable procedure.

IntroductionThe throwing motion in the javelin throw applies high loads to the musculoskeletal system of the shoulder, both in the acceleration and deceleration phases. While the loads occurring during the acceleration phase and their relationship to kinematics and energy flow have been relatively well investigated, there is a lack of studies focusing the deceleration phase. Therefore, the aim of this study is to investigate how the throwing arm is brought to rest, which resultant joint torques are placed on the shoulder and how they are influenced by the kinematics of the acceleration phase.MethodsThe throwing movement of 10 javelin throwers were recorded using a 12-infrared camera system recording at 300 Hz and 16 markers placed on the body. Joint kinematics, kinetics and energy flow were calculated between the touchdown of the rear leg and the timepoint of maximum internal rotation after release +0.1 s. Elastic net regularization regression was used to predict the joint loads in the deceleration phase using the kinematics and energy flow of the acceleration phase.ResultsThe results show that a significant amount of energy is transferred back to the proximal segments, while a smaller amount of energy is absorbed. Furthermore, relationships between the kinematics and the energy flow in the acceleration phase and the loads placed on the shoulder joint in the deceleration phase, based on the elastic net regularized regression, could be established.DiscussionThe results indicate that the loads of the deceleration phase placed on the shoulder can be influenced by the kinematics of the acceleration phase. For example, an additional upper body forward tilt can help to increase the braking distance of the arm and thus contribute to a reduced joint load. Furthermore, the energy flow of the acceleration phase can be linked to joint stress. However, as previously demonstrated the generation of mechanical energy at the shoulder seems to have a negative effect on shoulder loading while the transfer can help optimize the stress. The results therefore show initial potential for optimizing movement, to reduce strain and improve injury prevention in the deceleration phase.

PurposeThe KOOS-Child captures knee-related problems in everyday as well as sports activities and exists in numerous languages. This study aims to expand the field of application of the questionnaire to different target groups and to report a recovery profile of children with ACL-rupture.MethodsA translation of the KOOS-child was conducted using a multistage procedure. 127 children between 10 and 18 years of age were divided into groups of a) children with knee problems, b) elite volleyball players, c) obese children and d) control group. Test–retest reliability and internal consistency were assessed using Spearman’s correlation and Cronbach’s alpha. One-factor ANOVA was used to examine differences between groups. In order to examine longitudinal changes in Rehabs, the Friedman test was performed.ResultsAll subscales showed a high test-retest reliability (r ≥ .078) and an excellent internal consistency of α ≥ .90, with the exception of QoL (α = .86) and Symptoms (α = .75). Significant differences were found between the children with knee problems and the others (p < .01). The mean scores for all ACL participants increased during the first 12 months.ConclusionWith our study we provide preliminary reference values for a recovery profile after ACL rupture in children. In addition, the KOOS-Child does not have sufficient discriminatory power in healthy subjects and no longer differs statements in detail at the end of the rehabilitation process.Level of Evidence: IIb

Calculated intersegmental moments are commonly used in analyzing throwing movements. The inverse dynamics (ID) results can vary due to the chosen set of body segment inertia parameters (BSIP). A multitude of methods to determine BSIP sets are available. The purpose of this study was to clarify the influence of different estimation methods on the BSIPs and the respective impact on the ID results in javelin throwing. Movement kinematics were recorded for ten male javelin throwers. Six different methods were used to estimate BSIP sets for the upper extremities of each thrower. Subsequently, ID results were obtained for each thrower and BSIP set. Results show variations between 8% and 120% between the BSIP sets, and maximum intersegmental moments varied between 6% and 21%, respectively. Joint-specific variations of intersegmental moments were observed as well as movement-specific variations within a joint related to the different BSIP sets. Furthermore, the influence of BSIP sets appears to be subject-specific as well, with observed variations between 9% and 18% - some athletes are better represented by the chosen methods than others. Hence, our study results suggest that the method to determine BSIP sets needs to be carefully chosen for calculating joint kinetics in throwing movements.

Background: Team handball involves a tremendous amount of shoulder motion with high forces during repeated extended external range of motion. This causes shoulder complaints and overuse injuries. While eccentric training for the lower extremity shows preventive effects by improving strength, range of motion and fascicle length, there is a research gap for the shoulder joint and for advanced tissue characterization using diffusion tensor imaging.Objectives: To investigate the effects of 6-week eccentric isokinetic resistance training on strength, flexibility, and fiber architecture characteristics of the external rotators compared to an active control group in junior male handball players.Methods: 15 subjects were randomly assigned to the eccentric training group and 14 subjects to the active control group (conventional preventive training). Primary outcome measures were eccentric and concentric isokinetic strength of the external rotators, range of motion, and muscle fascicle length and fascicle volume.Results: The intervention group, showed significant changes in eccentric strength (+15%). The supraspinatus and infraspinatus muscles showed significant increases in fascicle length (+13% and +8%), and in fractional anisotropy (+9% and +6%), which were significantly different from the control group.Conclusion: Eccentric isokinetic training has a significant effect on the function and macroscopic structure of the shoulder external rotators in male junior handball players. While strength parameters and muscle structure improved, range of motion did not change. This research helps understanding the physiology of muscle and the role of eccentric training on shoulder function and muscle structure. Furthermore, DTI was found to be a promising tool for advanced tissue characterization, and the in vivo derived data can also serve as model input variables and as a possibility to extend existing ex-vivo muscle models. Future research is needed for functional and structural changes following convenient eccentric field exercises.

Background Performance in javelin throwing is dependent on the release speed and therefore the energy transferred to the javelin. Little is known about the flow of mechanical energy in javelin throwing and whether there is a connection to joint loading and throwing performance. The purpose of the study was therefore to investigate (1) the energy flow within the kinetic chain of the throwing arm, (2) how it is related to performance and joint loads and (3) how joint forces and torques are used to transfer, generate and absorb mechanical energy. Methods The kinematics of 10 experienced javelin throwers were recorded using a 12-camera infrared system. 16 markers were placed on the athlete’s body, five on the javelin to track the movement of each segment. A segmental power analysis was carried out to calculate energy flow between upper body, upper arm, forearm and hand. Stepwise regression analysis was used to calculate the variable that best predicts release speed and joint loads. Results The results indicate that the higher the peak rate of energy transfer from the thorax to the humerus, the higher the release speed and the joint loads. While there were no differences between the peak rate of energy transfer in the different joints, the energy transferred differed depending on whether joint forces or torques were used. It can be further shown that higher joint torques and thus higher rotational kinetics at the shoulder are linked to higher release speeds. Thus, the movements of the upper body can be of great influence on the result in javelin throwing. Furthermore, the data show that athletes who are able to transfer more energy through the shoulder, rather than generate it, experience a smaller joint loading. An effective technique for improved energy transfer can thus help perform at the same level while lowering joint stress or have higher performance at the same joint loading.

Strengthening the rotator cuff muscles is important for injury prevention and rehabilitation. Since muscle fascicle length improves motor performance and is suggested to reduce the risk of injury for the hamstring, it may be an important variable to promote multidirectional changes in the function and macroscopic structure for the shoulder. Recent literature reviews overwhelmingly suggest that eccentric exercises improve fascicle length and functional measures for the lower limb. However, there is a research gap for the shoulder. Since ultrasound imaging is the most commonly used imaging technique to quantify muscle structure, but has yielded heterogeneous results in different studies, there is another issue and a research gap for the imaging method. Based on the research gaps, the purpose of this study was to evaluate the effects of standardized eccentric strength training on the function and structure of the external rotator cuff muscles using an isokinetic dynamometer and MRI. Therefore, a preliminary pre-post intervention study was conducted and 16 physically active men were recruited in October 2021. For the right shoulder, an eccentric isokinetic training was performed twice a week for almost six weeks. The primary outcome measures (external rotators) were active and passive range of motion, eccentric and concentric torque at 30, 60, and 180°/s isokinetic speed, and fascicle length and fascicle volume for the supraspinatus and infraspinatus muscles. The findings show a training effect for the absolute mean values of eccentric strength (+24%, p = .008). The torque-angle relationship increased, especially in the final phase of range of motion, although a 4% (p = .002) decrease in passive range of motion was found in the stretch test. Positive changes in muscle structure were shown for the supraspinatus muscle fascicle length (+16%, p = .003) and fascicle volume (+19%, p = .002). Based on the study results, we can conclude that eccentric isokinetic training has a significant positive effect on the shoulder. To our knowledge, this is the first eccentric training study using both isokinetic dynamometer and muscle diffusion tensor imaging to access functional and structural changes in the human shoulder rotator cuff muscles. The methods were shown to be applicable for interventional studies. Based on these results, populations such as high-performance handball players with highly trained shoulders should be included in future studies.

Measurement of barbell velocity is a simple and effective way to control strength training. To assess the concurrent validity of different technological approaches measuring barbell velocity, video-analysis (Kinovea), linear velocity transducer (Speedograph), and an inertial measurement unit (V max Pro) were compared. Sixty-eight female and male sport science students lifted two repetitions in the bench press exercise at self-selected barbell loads. Peak vertical barbell velocity (V max ) was parallel measured during the concentric phase of the lift using the aforementioned devices. Concordance correlation coefficient (CCC), Deming regression (DR) and Bland-Altman analysis (BA) were used to assess relative and absolute concurrent validity of V max measured with Kinovea, Speedograph, and V max Pro. Results confirmed high concurrent validity of Speedograph and V max Pro (CCC = 0.99, standard deviation of differences [SDD] = 0.04 m∙s -1 ) without detecting proportional or constant bias. In contrast, V max measured with Kinovea showed poor concurrent validity to Speedograph (CCC = 0.83) and V max Pro (CCC = 0.81) with significant proportional and constant bias. Regression based re-calibration of V max from Kinovea resulted in an SDD = 0.09 m∙s -1 compared to Speedograph and an SDD = 0.08 m∙s -1 compared to V max Pro. Among the three tested devices, V max assessed using Kinovea showed poor concurrent validity. Furthermore, as Kinovea showed proportional bias compared to Speedograph and V max Pro, application-specific re-calibration of Kinovea should be applied when barbell velocity data is compared to Speedograph and V max Pro.

Hintergrund Adipositas führt durch das höhere Körpergewicht, eine häufig zu gering ausgebildete Muskelmanschette und eine Verschiebung der Beinachse zu einer chronischen Überlastung des Gelenkknorpels. Unklar ist, inwieweit das bereits bei Jugendlichen mit subklinischen Zeichen am Knorpel assoziiert ist. Da Überlastungen oder Fehlstellungen im Kniegelenk zu einer Erhöhung der T2-Relaxationszeit führen können, ist das T2-Mapping für diffuse und regionale Knorpelveränderungen noch sensitiver als konventionelle MR-Sequenzen wie PD-FS, T1 und T2.

The ability of muscle to generate force depends on its architecture and health condition. MR-based diffusion tensor imaging of muscle (mDTI) is an innovative approach for showing the fiber arrangement for the whole muscle volume. For accurate calculations of fiber metrics, muscle segmentation prior to tractography is regarded as necessary. Since segmentation is known to be operator dependent, it is important to understand how segmentation affects tractography. The aim of this study was to compare the results of deterministic fiber tracking based on muscle models generated by two independent operators. In addition, this study compares the results with a segmentation-free approach. Fifteen subjects underwent mDTI of the right shoulder. The results showed that mDTI can be successfully applied to complex joints such as the human shoulder. Furthermore, operator segmentation did not influence the results of fiber tracking and fascicle length (FL), fiber volume (FV), fractional anisotropy (FA), axial diffusivity (AD), radial diffusivity (RD), and mean diffusivity (MD) showed excellent intraclass correlation estimates (≥ 0.975). As an exploratory approach, the segmentation-free fiber tracking showed significant differences in terms of mean fascicle length. Based on these findings, we conclude that tractography is not sensitive to small deviations in muscle segmentation. Furthermore, it implies that mDTI and automatic segmentation approaches or even a segmentation-free analysis can be considered for evaluation of muscle architecture.

Purpose To investigate the potential effects of volleyball as a competitive sport in adolescence on the cartilage of knee joints using T2 mapping in MRI and identification of preclinical cartilage changes. Volleyball as an impact sport often leads to damage of the knee joint cartilage in adulthood. As T2 mapping is widely available and highly capable of detecting cartilage changes prior to conventional MRI sequences, such a detection may allow adolescent volleyball players to change their training regime before structural damage can occur to the cartilage and pose the risk of osteoarthritis. Materials and Methods Comparative study of the patellar, femoral, and tibial cartilage of 60 knee joints using T2 mapping on 3 T MRI. In each case, both knees of 15 adolescent competitive volleyball athletes were compared with 15 controls. Results In the group of competitive athletes, more focal cartilage changes were detected in the medial facet of the patellofemoral cartilage and in the medial femoral condyle of the knee joint cartilage (p = .01 and p <.05, respectively). Furthermore, the latter showed a diffused increase in maximal T2 mapping values (p <.04 right and p = .05 left). The distribution of changes seems to further depend on the player’s position. Conclusion In adolescent volleyball players in competitive sports, T2 mapping demonstrates early cartilage changes in both the patellofemoral and medial femoral cartilages. The distribution of lesions depends on the player’s position. Since the cascade from T2 relaxation time increase to conspicuous cartilage damage is well established, early counter-regulation (e. g., adapted training profile, targeted physiotherapy, and appropriate muscle building training) has the potential to prevent later damage. Key Points: Citation Format

Background Shoulder injuries are common causes for loss of training time and inability to compete. However, not only acute injuries are problematic, but also long-term changes of the stabilizing structures. While some studies are already available on the loading situation of the shoulder in baseball, this is not yet the case in javelin throwing, neither the kinematics nor the kinetics have been fully quantified so far. Objective The aim of the work was to quantify the load on the shoulder in the javelin throw, and thus contribute to the identification of injury risks. Materials and methods The javelin throwing motions of 10 male athletes were recorded using an infrared camera system and 18 retro-reflective markers. These data were used in a 5-segmental multibody model to calculate the kinematics and kinetics of the shoulder joint. The peak values were extracted from the different kinematic and kinetic time series and correlated with release speed. Results Athletes achieved a mean release velocity of 23.29 +/- 2.17 ms(-1). Maximum joint angular velocities ranged from 445-4071 degrees/s depending on the plane of motion. There were also plane-specific differences in joint loads, which ranged from 109-129 Nm. Conclusion Compared to baseball, the load situation in the javelin throw is different. While the javelin throw shows reduced amplitudes and angular velocities, an increased force requirement is visible. The reasons for this may be found in the different sets of rules (device weight/dimensions, input velocity).

A novel exoskeleton robotic system was developed to assist stair climbing. This active demonstrator consists of a motor with a cable system, various sensors, and a control system with a power supply. The objective of this preliminary study is a biomechanical evaluation of the novel system to determine its effectiveness in use. For this purpose, three test persons were biomechanically investigated, who performed stair ascents and descents with and without the exoskeleton. Kinematics, kinetics, and muscle activity of the knee extensors were measured. The measured data were biomechanically simulated in order to evaluate the characteristics of joint angles, moments, and reaction forces. The results show that the new exoskeleton assists both the ascent and the descent according to the measured surface electromyography (sEMG) signals, as the knee extensors are relieved by an average of 19.3%. In addition, differences in the interaction between the test persons and the system were found. This could be due to a slightly different operation of the assisting force or to the different influence of the system on the kinematics of the users.