Sports Science

Relationship between Range of Motion, Strength, Upper Quarter Y-balance Test and a history of Shoulder Injury among NCAA Division I Overhead Athletes

Background: Several risk factors have been identified as contributors to the development of shoulder injuries, including glenohumeral internal rotation deficit, rotator cuff weakness, and shoulder instability. However, lasting deficits of the physical characteristics among overhead athletes with a history of a shoulder injury are unknown. Objective: To compare shoulder range of motion (ROM), strength, and upper-quarter dynamic balance between collegiate overhead athletes with and without a history of a shoulder injury. Methods: 58 overhead athletes were distributed into a shoulder injury history group (n=25) and healthy group (n=33). All participants were fully participating in NCAA Division I baseball, softball, volleyball, or tennis and free of any symptoms of shoulder injuries. An investigator measured active ROM for dominant shoulder internal rotation (IR), external rotation (ER), and horizontal adduction (HAD) using a digital inclinometer. Isometric strength for dominant shoulder IR and ER at 90° of abduction was measured using a hand-held dynamometer. The upper quarter dynamic balance was assessed via the Upper Quarter Y-Balance Test (UQYBT). Results: The injury group demonstrated a lower UQYBT mean score in the superolateral direction. However, there were no statistically significant intergroup differences in shoulder ROM, strength, ER/IR strength ratio, and UQYBT in the medial direction and inferolateral direction. Conclusions: Overhead athletes with a previous history of shoulder injury had poorer UQYBT in the superolateral direction despite a lack of ongoing symptoms or deficits in function. Well-planed dynamic balance training and related strengthening exercises may be warranted for overhead athletes to improve their upper quarter functions.
Listed In: Physical Therapy, Sports Science, Other


Could lowering the tackle height law to below the chest in rugby union reduce long-term brain degeneration?

The tackle height law in rugby union has been an area of concern for many years. It is currently set at the line of the ball carrier’s shoulder. The goal of this study is to use Model-Based Image-Matching (MBIM) and human volunteer tackles in a marker-based 3D motion analysis laboratory to examine the severity of a legal tackle to the shoulder/chest of the ball carrier (with no head contact) and the effect of tackles above and below the chest on ball carrier inertial head kinematics, respectively. From the real-world tackles, the estimated ball carrier peak resultant change in head angular velocity was 30.4 rad/s (23.1 rad/s, 14.0 rad/s and 21.8 rad/s in the coronal, sagittal and transverse direction, respectively). In the staged tackles, the median peak resultant head linear and angular acceleration and change in head angular velocity values for tackles above the chest were greater than for below the chest. The results support the proposition of lowering the current tackle height law. Due to the real-world tackle (MBIM), the ball carrier head kinematics indicated a greater than 75% chance of sustaining a concussion, based on the literature. This was the case even though no contact was made with the ball carrier’s head. Therefore, repeatedly engaging in this type of legal tackle may be detrimental for long-term brain health. However, by lowering the tackle height law to below the chest, ball carrier inertial head kinematics can be reduced significantly, thus reducing the repetitive loading placed on the brain.
Listed In: Biomechanical Engineering, Biomechanics, Sports Science


Kinetics and kinematics of the lower extremity during performance of two typical Tai Chi movements by the elders

Tai Chi (TC) has the rehabilitative potential to prevent falls in the elderly, however it is unclear how TC training improves postural control capacity. Fifteen male participants with more than 4 years of TC experience were asked to perform two TC movements, the “Repulse Monkey (RM)” and “Wave-hands in clouds (WHIC).” Three-dimensional (3-D) temporospatial, kinematic and kinetic data was collected using VICON motion analysis system with 10 infrared cameras and 4 force plates. Stride width, step length, step width, single- and double-support times, center of mass (COM) displacement, peak joint angles, range of motion, peak joint moments, time to peak moment, and ground reaction force (GRF) were analyzed. The differences in the measurements of the two TC movements were compared with walking using two-way ANOVA analysis. Compared with walking kinematics, both TC movements spent less time in single-support; RM and WHIC had larger mediolateral and vertical displacement of the COM. Compared with walking kinetics, both TC movements generated significantly smaller peak ground reaction forces in all directions, except the anterior; larger hip extension, adduction and internal rotational moments, knee adduction/abduction and internal rotation moments and eversion/inversion and external/internal moments of ankle–foot; and longer peak moment generation time for hip extension, adduction and internal rotation, knee extension and ankle dorsiflexion and inversion. The slow, gentle stepping-action and loading patterns that are consistent with the mechanical behavior of biological tissues. These two TC movements would be suitable training to help strengthen the lower extremities and prevent falls in the elderly.
Listed In: Biomechanics, Gait, Sports Science


Association of isometric hip and ankle strength with frontal plane kinetics in females during running

Frontal plane mechanics have been associated with running-related injuries such as patellofemoral pain. Strengthening and gait retraining programs aimed at reducing hip adduction during running have been shown to be effective at alleviating symptoms, however evidence of their effect on running kinematics is equivocal. It is possible that such programs exert their benefits through altering kinetics rather than kinematics in the frontal plane during running. Further, the contributions of the ankle to frontal plane mechanics have not been well studied. PURPOSE: To determine if hip and ankle strength are associated with frontal plane kinetics in female runners. METHODS: 64 healthy women running at least 16km per week participated in this study. Isometric hip abduction and ankle inversion strength were measured using a handheld dynamometer. 3D gait analysis was conducted as participants ran on an instrumented treadmill at 2.7 m/s. Participants were ranked in order of isometric strength of both the hip and ankle, and divided into tertiles of high, medium and low strength. 2-way MANOVA was used to determine the relationship between strength and peak moment, positive work and negative work in the frontal plane of the hip and the ankle. Tukey post-hoc tests were conducted where applicable (α=0.05). RESULTS: There was no significant interaction effect, or main effect of hip strength. There was a significant main effect of ankle strength on frontal plane kinetics (p=0.024). Specifically, the strong ankle group compared to the weak ankle group had significantly greater magnitude of peak ankle inversion moment (0.95(0.32) vs 0.68(0.22) Nm/kg, p=0.033), hip abduction moment (-2.78(1.02) vs -1.88(0.24) Nm/kg, p=0.002) and hip frontal plane positive work (0.27(0.19) vs. 0.13(0.03) W/kg, p=0.006). CONCLUSION: Isometric ankle but not hip strength is associated with kinetics in the frontal plane during running in females. Thus ankle strength should not be overlooked in clinical evaluation and treatment of runners.
Listed In: Biomechanics, Gait, Physical Therapy, Sports Science


Hinged ankle braces do not alter knee mechanics during sidestep cutting

Lateral ankle sprains, caused by rapid ankle inversion, and noncontact anterior cruciate ligament (ACL) knee injuries, caused by excessive knee loading, are among the most common lower extremity injuries that occur during dynamic tasks, such as cutting. Ankle braces are commonly used to prevent lateral ankle sprains by reducing ankle inversion. There is limited and conflicting research about how an ankle brace affects other joints, such as the knee, during cutting movements. It is also not known if sex differences exist during a cutting task when an ankle brace is present. The purpose of this study was to determine the effects of an Ultra Zoom® hinged ankle brace and sex on ankle and knee biomechancis during a cutting maneuver. Eighteen recreationally active adults completed sidestep cutting trials with and without an Ultra Zoom® ankle brace. Three-dimensional ankle and knee kinematics and GRF were collected. Separate 2×2 (sex × brace) repeated measures ANOVAs were used. Results indicated the brace reduced frontal plane ankle kinematics and had no effect on knee kinematics. Additionally, females demonstrated decreased knee flexion compared to males. An ankle brace during a cutting maneuver restricted frontal plane ankle movement. Furthermore, the only significant changes in knee mechanics were due to sex differences, which has been well documented. These findings indicate that the use of an Ultra Zoom® hinge brace is suitable for sports, reduces the risk of lateral ankle injuries, and does not alter knee mechanics, and therefore may not increase the risk of ACL injury.
Listed In: Biomechanics, Sports Science


Increased Role of the Secondary Passive Stabilizers Following Complete but Not Partial Loss of Anterior Cruciate Ligament Function During Post-Natal Growth

Robotic testing was performed with a 6-degree of freedom load cell in order to analyze functional contributions of the soft tissues in the knee under physiologically relevant loading conditions. Age groups ranging from 1.5 months to 18 months, porcine equivalent to early youth through late adolescent human ages, were studied. Complete ACL transection resulted in increased APTT and VVR across all ages (p<0.05), while injury to the AM bundle did not affect APTT or VVR. Additionally, increasing age resulted in decreased APTT normalized to the tibial plateau (p<0.05) and an average 19° decrease in VVR across states from 0 to 18 months of age (p<0.05). The ACL was the primary restraint against anterior drawer in the intact knee state [75-111%]. Following AM bundle dissection, the PL bundle carried the vast majority of the anterior load regardless of age [66-112%]. Following complete ACL transection, the MCL and medial meniscus carried most of the force across ages under anterior drawer. The LCL contributed increasing resistance to varus torque across states with age, as did the MCL under valgus torque.
Listed In: Biomechanical Engineering, Biomechanics, Orthopedic Research, Sports Science


Static Foot Structure May Predict Midfoot Mechanics

INTRODUCTION: Clinical interventions for foot injury prevention are often prescribed based on static measures of foot structure. However, this convention merits further investigation as the static-dynamic relationship has only been explored in walking and running. The primary aim of this study was to explore the relationship between static foot structure and dynamic midfoot kinematics and kinetics during a barefoot single-leg landing. METHODS: 48 females (age=20.4±1.8 yr, height=1.6±0.06 m, weight=57.3±5.5 kg) completed the study. Standing arch height index (AHI) was measured using the Arch Height Index Measurement System. Skin markers were attached using a multi-segment foot model by Bruening et al.1 A14-camera motion capture system (Vicon) was used to sample kinematic data at 250Hz while two force platforms (AMTI) sampled kinetic data at 1000Hz. A static trial was captured then subjects hung from wooden rings and performed barefoot single-leg drop landings from a height of 0.4m. Metrics were calculated in Visual 3D (C-motion, Inc.) to obtain static midfoot angle (MA), midtarsal range of motion (ROM), and midtarsal work. PCCs were calculated for static and dynamic variables using paired t-tests in SAS. RESULTS: AHI was correlated negatively with sagittal plane midtarsal ROM (r=-0.32032, p=0.0264) and positively with midtarsal work (r=0.33180, p=0.0212). MA was correlated positively with sagittal plane midtarsal ROM (r=0.48336, p=0.0005) and negatively with midtarsal work (r=-0.32321, p=0.0250). DISCUSSION/CONCLUSION: Static foot structure may be a valuable clinical tool in assessing midfoot function relating to injury risk in athletes, who participate in high-impact loading activities, as well as in pathological populations.
Listed In: Biomechanics, Orthopedic Research, Physical Therapy, Sports Science


Effects of acute plantarflexion stretching on anterior cruciate ligament loading during single-leg landing

Research has shown decreases in dorsiflexion ROM appear to be predictors for non-contact ACL injuries during landing tasks. The gastrocnemius-soleus complex (GSC) plays a critical role in dorsiflexion ROM, with a less compliant GSC decreasing dorsiflexion ROM. However, it is unknown whether acute GSC stretching can decrease ACL loading during landing tasks. Fifteen active participants completed three trials of single-leg drop-landings from a box. 3D-lower extremity kinematics and kinetics were captured using 3D-motion capture system and force plate. Between assessments, all participants completed a three-minute bout of stretching targeting the GSC. Musculoskeletal modeling was used to estimate ACL loading in the sagittal, frontal, and transverse planes, overall peak ACL loading, and time to peak ACL loading. Pretest and posttest ACL loading variables were compared with paired t-tests (p≤0.05). No significant differences were found between pre-stretch and post-stretch peak ACL loading time, peak frontal plane ACL loading, and peak transverse plane ACL loading (p>0.05). However, post-stretch peak sagittal plane ACL loading was significantly higher compared to pre-stretch peak sagittal plane ACL loading (p=0.008). Furthermore, overall post-stretch peak ACL loading was significantly higher compared to overall pre-stretch peak ACL loading (p=0.022). As the gastrocnemius plays a role in knee flexion, it is possible that an acute bout of stretching may increase gastrocnemius compliance, therefore increase in sagittal plane ACL loading. An increase in sagittal plane loading would also lead to an overall loading effect on the ACL. Future studies warrant investigation into the effects of chronic GSC stretching on ACL loading.
Listed In: Biomechanics, Sports Science


Head Acceleration During Girls Youth Soccer Using Real Time Data

Title:  Head Acceleration During Girls Youth Soccer Using Real Time Data   Emily Messerschmidt, Katlyn Van Patten, Ryan Lee, Srikant Vallabhajosula Purpose/Hypothesis: While the acute effects of concussion have been the focus of research in the past, there is a new emphasis toward following the cumulative effects of sub-concussive head accelerations in athletics. This is especially important in youth athletes because the developing brain is more vulnerable to injury from head trauma in sports like soccer due to techniques such as heading, that can result in numerous head impacts throughout play. There is a current lack of evidence on the magnitude and frequency of head accelerations that occur during real-time youth sports, including soccer, and whether these accelerations have a detrimental cumulative effect. The purpose of the current study was to measure the head acceleration that youth athletes experience during real-time soccer games.   Number of Subjects: 31 under-15 girls club soccer participants. 11 players monitored each game.   Materials/Methods: 3 season games were observed. Triax Smart Impact Monitor headband accelerometers were worn during gameplay to collect real-time head impact data. Forces >10g were recorded. Games were video recorded for further analysis. Head impacts were categorized by type of impact: purposeful header (PH), player to player (PP), player to ground (PG), and ball to head (BH). Data was analyzed using descriptive statistics.   Results: A total of 171 impacts were observed (PH=20, PP=113, PG=36, BH=2). Only one impact recorded was above the concussion threshold of 70g. The majority (77%) of impacts observed were <10g. Of the accelerations recorded, PH resulted in the largest average acceleration (36.8±14.9g) followed by PG (20.5±4.2g), and PP (19.5±4.6g). The maximum accelerations for PH, PG and PP were 73g, 26g and 30g respectively. No BH accelerations were recorded >10g.   Conclusions: While PH yielded the highest average acceleration, it was one of the least frequently occurring impacts. PP impacts were most common however the majority produced little to no head acceleration. While there was variability of head acceleration that occurred within each type of impact, none produced consistently dangerous (≥70g) accelerations. Clinical Relevance: This study provides preliminary evidence of the impacts sustained during girls youth soccer games for athletic trainers or sports physical therapists who are monitoring athletes for concussions. The findings reveal that the use of headband accelerometers to measure real-time data can be a useful tool to monitor multiple players on the field. There remains a need for further research into the effect of cumulative sub-concussive impacts during soccer in youth athletes with larger sample size. Further studies should investigate the impacts players sustain over multiple seasons to observe if those who experience multiple sub-concussive impacts report concussion-like symptoms or show concussion-like signs. Additionally, this study adds evidence to the existing literature that the use of video analysis to confirm the occurrence of impacts and to correctly categorize them is highly beneficial to ensure reliability in future studies.
Listed In: Biomechanics, Physical Therapy, Sports Science


An Assessment of a novel approach for determining the player kinematics in elite rugby union players

Rugby is intrinsically an impact sport which results in concussions being a frequent injury within the game. Repeated concussion is linked to early-onset dementia and depression, and the rules for limiting repeated concussion are an ongoing controversy. Therefore a greater understanding of the dynamics of head impacts in rugby and the mechanism of concussion is required. Accordingly, this study focuses on assessing the use of Model Based Image Matching (MBIM) and multi-camera view video for measuring six degree of freedom head kinematics during an impact event in rugby union. The matching is performed on video evidence using 3-D animation software Poser 4. The surroundings are built in the virtual environment based on the real dimensions of the sport field. A skeleton model is then used to fit the player’s anthropometry for each video frame thus allowing player kinematics to be measured. The results from this initial study suggest that the MBIM method can be applied to head impact cases in rugby union. The head kinematics results from this case are similar to those reported in literature. The MBIM method should be applied to a number of head impact cases to establish thresholds for concussion injuries in rugby. The data gained from the MBIM method can allow for more reliable kinematic data to be inputted into finite element analysis and rigid body simulations of concussion impacts. This can allow multi-axis force measurements to be measured within the brain and neck. This can ultimately lead to an improvement in concussion injury prevention and management.
Listed In: Biomechanical Engineering, Biomechanics, Mechanical Engineering, Sports Science