Estimating resource bounds for software transactions

We present an effect based static analysis to calculate upper and lower bounds on the memory resource consumption in a transactional calculus. The calculus is a concurrent variant of Featherweight Java extended by transactional constructs. The model supports nested and concurrent transactions. The analysis is compositional and takes into account implicit join synchronizations that arise when more than one thread perfom a join-synchronization when jointly committing a transaction. Central for a compositional and precise analysis is to capture as part of the effects a tree-representation of the future resource consumption and synchronization points (which we call joining commit trees). We show the soundness of the analysis

Athletes with high knee abduction moments show increased vertical center of mass excursions and knee valgus angles across sport-specific fake-and-cut tasks of different complexities

Young female handball players represent a high-risk population for anterior cruciate ligament (ACL) injuries. While the external knee abduction moment (KAM) is known to be a risk factor, it is unclear how cutting technique affects KAMs in sport-specific cutting maneuvers. Further, the effect of added game specificity (e.g., catching a ball or faking defenders) on KAMs and cutting technique remains unknown. Therefore, this study aimed: (i) to test if athletes grouped into different clusters of peak KAMs produced during three sport-specific fake-and-cut tasks of different complexities differ in cutting technique, and (ii) to test whether technique variables change with task complexity. Fifty-one female handball players (67.0 ± 7.7 kg, 1.70 ± 0.06 m, 19.2 ± 3.4 years) were recruited. Athletes performed at least five successful handball-specific sidestep cuts of three different complexities ranging from simple pre-planned fake-and-cut maneuvers to catching a ball and performing an unanticipated fake-and-cut maneuver with dynamic defenders. A k-means cluster algorithm with squared Euclidean distance metric was applied to the KAMs of all three tasks. The optimal cluster number of koptimal = 2 was calculated using the average silhouette width. Statistical differences in technique variables between the two clusters and the tasks were analyzed using repeated-measures ANOVAs (task complexity) with nested groupings (clusters). KAMs differed by 64.5%, on average, between clusters. When pooling all tasks, athletes with high KAMs showed 3.4° more knee valgus, 16.9% higher downward and 8.4% higher resultant velocity at initial ground contact, and 20.5% higher vertical ground reaction forces at peak KAM. Unlike most other variables, knee valgus angle was not affected by task complexity, likely due to it being part of inherent movement strategies and partly determined by anatomy. Since the high KAM cluster showed higher vertical center of mass excursions and knee valgus angles in all tasks, it is likely that this is part of an automated motor program developed over the players' careers. Based on these results, reducing knee valgus and downward velocity bears the potential to mitigate knee joint loading and therefore ACL injury risk

Estimating whole-body mechanical power in running by means of simulated inertial sensor signals

The Purpose of this study was to identify the potential of inertial sensor information to estimate whole-body mechanical power (WBP) in running. We recorded three-dimensional (3D) whole-body kinematic and kinetic data of eleven male subjects by means of optoelectronic motion capturing and an instrumented treadmill at speeds between 2.0 and 3.5 m/s. We simulated 3D acceleration and gyroscope signals for 15 segments of the whole body from marker trajectory data. We calculated one statistical model for each subject to estimate WBP from a set of 279 predictor variables derived from simulated sensor signals. Overall, WBP was estimated with root mean square errors between 4% and 20%. This highlights the potential of inertial sensor signals to estimate WBP. Nonetheless, in its current form, the method requires too many sensors for practical applications

SPEED AND SLOPE EFFECTS ON METATARSOPHALANGEAL JOINT KINEMATICS IN RUNNING

The purpose of this study was to describe the effects of running speed and slope on metatarsophalangeal (MTP) joint kinematics. 22 male and female runners underwent 3D motion analysis on an instrumented treadmill at three different speeds (2.5 m/s, 3.0 m/s, 3.5 m/s). At each speed, participants ran at seven slope conditions (downhill: -15%, -10%, -5%, level, and uphill: +5%, +10%, +15%). We found a significant main effect (p \u3c 0.001) of running speed and slope on peak MTP dorsiflexion and a running speed by slope interaction effect (p \u3c 0.001) for peak MTP dorsiflexion velocity. These findings highlight the need to consider running intensity and environmental factors like running surface inclination when considering MTP joint mechanics and technological aids to support runners

Running-Related Biomechanical Risk Factors for Overuse Injuries in Distance Runners: A Systematic Review Considering Injury Specificity and the Potentials for Future Research

Background: Running overuse injuries (ROIs) occur within a complex, partly injury-specific interplay between training loads and extrinsic and intrinsic risk factors. Biomechanical risk factors (BRFs) are related to the individual running style. While BRFs have been reviewed regarding general ROI risk, no systematic review has addressed BRFs for specific ROIs using a standardized methodology. Objective: To identify and evaluate the evidence for the most relevant BRFs for ROIs determined during running and to suggest future research directions. Design: Systematic review considering prospective and retrospective studies. (PROSPERO_ID: 236,832). Data Sources: PubMed. Connected Papers. The search was performed in February 2021. Eligibility Criteria: English language. Studies on participants whose primary sport is running addressing the risk for the seven most common ROIs and at least one kinematic, kinetic (including pressure measurements), or electromyographic BRF. A BRF needed to be identified in at least one prospective or two independent retrospective studies. BRFs needed to be determined during running. Results: Sixty-six articles fulfilled our eligibility criteria. Levels of evidence for specific ROIs ranged from conflicting to moderate evidence. Running populations and methods applied varied considerably between studies. While some BRFs appeared for several ROIs, most BRFs were specific for a particular ROI. Most BRFs derived from lower-extremity joint kinematics and kinetics were located in the frontal and transverse planes of motion. Further, plantar pressure, vertical ground reaction force loading rate and free moment-related parameters were identified as kinetic BRFs. Conclusion: This study offers a comprehensive overview of BRFs for the most common ROIs, which might serve as a starting point to develop ROI-specific risk profiles of individual runners. We identified limited evidence for most ROI-specific risk factors, highlighting the need for performing further high-quality studies in the future. However, consensus on data collection standards (including the quantification of workload and stress tolerance variables and the reporting of injuries) is warranted

Reliability of Running Stability during Treadmill and Overground Running

Running stability is the ability to withstand naturally occurring minor perturbations during running. It is susceptible to external and internal running conditions such as footwear or fatigue. However, both its reliable measurability and the extent to which laboratory measurements reflect outdoor running remain unclear. This study aimed to evaluate the intra- and inter-day reliability of the running stability as well as the comparability of different laboratory and outdoor conditions. Competitive runners completed runs on a motorized treadmill in a research laboratory and overground both indoors and outdoors. Running stability was determined as the maximum short-term divergence exponent from the raw gyroscope signals of wearable sensors mounted to four different body locations (sternum, sacrum, tibia, and foot). Sacrum sensor measurements demonstrated the highest reliabilities (good to excellent; ICC = 0.85 to 0.91), while those of the tibia measurements showed the lowest (moderate to good; ICC = 0.55 to 0.89). Treadmill measurements depicted systematically lower values than both overground conditions for all sensor locations (relative bias = -9.8% to -2.9%). The two overground conditions, however, showed high agreement (relative bias = -0.3% to 0.5%; relative limits of agreement = 9.2% to 15.4%). Our results imply moderate to excellent reliability for both overground and treadmill running, which is the foundation of further research on running stability

EFFECT OF DOWNHILL RUNNING ON BIOMECHANICAL RISK FACTORS ASSOCIATED WITH ILIOTIBIAL BAND SYNDROME

The purpose of this study was to identify the influence of downhill running on biomechanical risk factors for iliotibial band syndrome. We conducted a 3D motion analysis of 22 females and males running on an instrumented treadmill at four different inclinations (0%, -5%, -10%, -15%) at a speed of 3.5 m/s. We found significant differences for biomechanical risk factors associated with iliotibial band syndrome. Peak knee flexion angle at initial ground contact (p \u3c .001), peak knee adduction angle (p = .005), and iliotibial band strain (p \u3c .001) systematically increased with increasing slope. Downhill running increases biomechanical risk factors for iliotibial band syndrome. Our results highlight the need to consider the individual running environment in assessing overuse injury risk in runners

LOWER SPINE LOADING AND PELVIC KINEMATICS THROUGHOUT A NEAR-MAXIMAL 10 KM RUN

The purpose of the present study was to investigate the effects of fatigue on lower back loading and pelvis kinematics in distance running. Kinetic and kinematic data of the whole body was recorded for 13 subjects during a near-maximal 10-km run. Pelvis kinematics were calculated in 3D while moments acting on the lumbar spine were determined by using a full body lumbar spine model in OpenSim. We found significant effects of running distance for pelvis kinematics in the transversal and sagittal plane whereas the lumbar spine moments increased significantly in the frontal and transversal plane. These results support earlier findings suggesting a connection between running and spinal or pelvic overuse injuries. Thus, distance runners should focus on a controlled arm swing and upper body rotation as well as pelvis stabilization

INTER TREADMILL VARIATION IN BELT VELOCITY REGULATION

The purpose of the present study was to develop a novel method to quantify instantaneous belt velocity and to investigate differences in belt velocity regulation between different types of treadmills. We used circular cut-outs of reflective tape attached to the lateral aspects of the treadmill to determine its instantaneous belt velocity. By testing three treadmills with seven participants we were able to identify clearly different instantaneous belt velocity patterns between treadmills. Peak deviation amplitudes correlated positively with the body mass of runners, even though the slope of this relationship was different between treadmills for positive deviations from target speed. These results highlight the importance of considering belt velocity regulation differences in human locomotion studies and treadmill training