Visual feedback improves propulsive force generation during treadmill walking in people with Parkinson disease.

Persons with Parkinson's disease experience gait alterations, such as reduced step length. Gait dysfunction is a significant research priority as the current treatments targeting gait impairment are limited. This study aimed to investigate the effects of visual biofeedback on propulsive force during treadmill walking in persons with Parkinson's. Sixteen ambulatory persons with Parkinson's participated in the study. They received real-time biofeedback of anterior ground reaction force during treadmill walking at a constant speed. Peak propulsive force values were measured and normalized to body weight. Spatiotemporal parameters were also assessed, including stride length and double support percent. Persons with Parkinson's significantly increased peak propulsive force during biofeedback compared to baseline (p <.0001, Cohen's dz = 1.69). Variability in peak anterior ground reaction force decreased across repeated trials (p <.0001, dz = 1.51). While spatiotemporal parameters did not show significant changes individually, stride length and double support percent improved marginally during biofeedback trials. Persons with Parkinson's can increase propulsive force with visual biofeedback, suggesting the presence of a propulsive reserve. Though stride length did not significantly change, clinically meaningful improvements were observed. Targeting push-off force through visual biofeedback may offer a potential rehabilitation technique to enhance gait performance in Persons with Parkinson's. Future studies could explore the long-term efficacy of this intervention and investigate additional strategies to improve gait in Parkinson's disease.

Lower Body Joint Moments during the Golf Swing in Older Adults: Comparison to Other Activities of Daily Living.

Golf participation has increased dramatically in the last several years. With this increase in participation, clinicians need better evidenced based strategies to advise those golfers with different pathologies when it is safe to return to the game. Golf teaching professionals also need to understand how to alter golf mechanics to protect injured and/or diseased joints in golfers to allow them to play pain free and avoid further injury. This study used a 3-dimensional link segment model to calculate the net joint moments on the large lower limb joints (knee and hip) during golf (lead and trail leg) and two commonly studied activities of daily living (gait and sit-to-stand) in 22 males, healthy, adult golfers. It also examined the correlations between these knee and hip joint loads and club head speed. The external valgus knee moment and the internal hip adduction moment were greater in the lead leg in golf than in the other activities and were also correlated with club head speed. This indicates a strategy of using the frontal plane GRF moment during the swing. The internal hip extension and knee flexion moment were also greater in the golf swing as compared with the other activities and the hip extension moment was also correlated with club head speed. This emphasizes the importance of hip extensor (i.e., gluteus maximus and hamstring) muscle function in golfers, especially in those emphasizing the use of anterior-posterior ground reaction forces (i.e., the pivoting moment). The golf swing places some loads on the knee and the hip that are much different than the loads during gait and sit-to-stand tasks. Knowledge of these golf swing loads can help both the clinician and golf professional provide better evidence-based advice to golfers in order to keep them healthy and avoid future pain/injury.

Acclimatization of force production during walking in persons with Parkinson's disease.

Individuals with Parkinson's disease walk slowly, with short strides resulting in decreased mobility. Treadmill walking assessments are utilized to understand gait impairment in persons with Parkinson's disease and treadmill-based interventions to mobility have become increasingly popular. While walking on a treadmill, there is a reported initial acclimatization period where individuals adjust to the speed and dynamics of the moving belt before producing consistent walking patterns. It is unknown how much walking time is required for individuals with Parkinson's disease to acclimate to the treadmill. We investigated how spatiotemporal parameters and ground reaction forces changed during treadmill acclimatization. Twenty individuals with idiopathic Parkinson's (15 Males, 5 Females) walked for a five-minute treadmill session on an instrumented treadmill while motion capture data were collected. The measures of interest included ground reaction force measures (peak propulsive force, peak braking force, propulsive impulse, and braking impulse) and spatiotemporal measures (stride length, stride time, or double support time). Analyses demonstrated significantly increased propulsive impulse (p <.001) after the first minute, with no significant difference for the remaining minutes (p ≥ 0.395). There were no significant changes in the spatiotemporal measures (P =.065). These results quantify the stabilization of ground reaction force during the treadmill acclimatization period. Based on our findings, if steady-state gait is desired, we recommend participants walk for at least two minutes before data collection. Future clinical investigations should consider ground reaction force as sensitive parameters for evaluating gait in persons with Parkinson's disease in treadmill-based assessments or interventional therapies.

The effect of limb selection methods on gait analysis in Parkinson's disease.

INTRODUCTION: Asymmetry of motor symptoms is a common characteristic of Parkinson's disease (PD), yet gait outcomes are often reported as limb averages or authors fail to report which limb is being analyzed. This study aimed to investigate how varying limb selection methods may impact statistical comparisons of common gait measures amongst fallers and non-fallers with PD. METHODS: Overground walking data was collected on 53 fallers and 117 non-fallers during routine clinical visits. The relationship between limb selection method (left, right, most-affected, least-affected, and limbs averaged) and faller status (faller vs non-faller) on spatiotemporal gait parameters was analyzed using a mixed linear model. RESULTS: Significant interactions between limb selection method and faller status were found for step time variability and swing time variability. Regardless of selection method, it was possible to discern significant differences between fallers and non-fallers. Yet, if researchers only analyze the least-affected limb during gait analysis, the differences between fallers and non-fallers are less apparent. CONCLUSION: In individuals experiencing uneven laterality of symptoms that affect gait, limb averaging may alter interpretation of statistical findings and mask compensation patterns. This study promotes a refined gait analysis process, particularly in individuals that present with possible asymmetric walking. Including limb selection methods in future studies encourages holistic and transparent analyses within the literature.

Walking indoors, outdoors, and on a treadmill: Gait differences in healthy young and older adults.

BACKGROUND: Although human gait is typically studied in a laboratory environment, the findings of laboratory-based gait assessments are often applied to daily life scenarios. Assessing gait in varied conditions may offer a better understanding of the influence of environment on gait performance. RESEARCH QUESTIONS: How do spatiotemporal gait measures differ between indoor overground walking, outdoor walking, and treadmill walking in healthy adults? Do different walking environments exaggerate age-related alterations in gait performance in older compared to young adults? METHODS: 30 young (18-30yrs) and 28 older adults (60-80yrs) completed four randomized conditions at their typical, comfortable walking pace: 1) 8 m of indoor walking, 2) continuous indoor walking, 3) treadmill walking, and 4) outdoor walking on a sidewalk. Wearable inertial sensors recorded gait data and the magnitudes and variability (in standard deviations) of the following gait measures were computed: cadence, percent double support, stride length (with sample entropy), and gait velocity. RESULTS: Despite the lack of significant univariate interactions between group and walking condition, significant main effects for condition and group were observed in both the magnitude and variability analyses. Treadmill walking resulted in a slower gait with shorter, less variable strides (p < .001), while walking outdoors resulted in faster gait with longer strides (p < .001) compared to other walking conditions. Stride length regularity was reduced when walking outdoors compared to treadmill walking (p = .019). SIGNIFICANCE: The results showed that the effects of walking condition on gait measures were more dramatic than participant age, and gait performance differs between walking environments in both older and younger adults. Since daily life gait encompasses both tightly controlled and unconstrained, free-living walking, researchers and clinicians should use caution when generalizing gait performance across walking conditions. Measures of gait performance typically used in laboratory gait analyses may not adequately characterize daily life gait in indoor and outdoor environments.

Faster or longer steps: Maintaining fast walking in older adults at risk for mobility disability.

BACKGROUND: The ability to walk at various speeds is essential to independence for older adults. Maintaining fast walking requires changes in spatial-temporal measures, increasing step length and/or decreasing step time. It is unknown how mobility affects the parameters that change between preferred and fast walking. RESEARCH QUESTION: How does preferred walking performance and measures of strength and mobility relate to the approach (decreasing step time or increasing step length) older adults at risk for mobility disability use to maintain fast walking speeds?. METHODS: Peak isokinetic dynamometry of knee and ankle and several mobility evaluations, including the Timed Up-and-Go, Short Physical Performance Battery, and Dynamic Gait Index, assessed mobility and strength in 57 participants, aged 65-80. Biomechanical gait analysis was used to analyze step length, step time, gait speed at preferred and fast gait speeds and ground reaction force during preferred walking. A score combining the differences between step length and time at fast and preferred speeds (Length-Time Difference) separated participants into two groups: (1) Length, representing a predominant increase in step length to walk fast and (2) Time, a predominant decrease in step time. RESULTS: Those who decreased step time to produce increased speed performed worse during repeated chair stands (p = .006) with no difference in isokinetic strength (p ≥ .15). During preferred walking, the Time group displayed increased propulsive impulse compared to the Length group (p = .007), despite no differences in preferred speed, step length, or time (p ≥ .50). SIGNIFICANCE: While kinetics of preferred walking differed between groups separated by Length-Time Difference, basic spatial-temporals of preferred walking did not in this homogenous population. Length-Time Difference relates to a common mobility assessment and could be easily calculated by clinicians to provide a quantitative and more sensitive measure of ambulatory performance.

Levodopa facilitates improvements in gait kinetics at the hip, not the ankle, in individuals with Parkinson's disease.

Parkinson's disease symptoms impair gait, limit mobility, and reduce independence. Levodopa improves muscle activation, strength, and coordination; thus, facilitating increased step length, but few studies have evaluated the underlying forces associated with medication-induced gait improvements. Here, we assess the effects of levodopa on gait kinetics in persons with Parkinson's disease. Over two sessions, 13 participants with Parkinson's disease walked on a treadmill while both optimally medicated and after a 12-hour medication withdrawal. Walking was analyzed for spatiotemporal parameters, ranges of motion, anterior-posterior ground reaction forces, joint torques, and powers using an instrumented treadmill and motion capture system. When on medication, participants increased gait speed by significantly improving step length (p = .009) and time (p = .004). Peak propulsive force (p = .001) and hip flexion torques (p = .003) increased with medication while hip extensor and ankle plantarflexor torques did not. While differences in joint power were not significantly different, the optimal medication condition showed medium to large effects, with the largest effect at the hip (dz = 0.84). Our findings suggest the underlying forces responsible for the increases in gait speed are primarily due to increases at the hip, with limited change at the ankle. Disproportionate use of muscle force may be a limiting factor for levodopa's use as an intervention for walking. Future interventions should consider targeting force production deficits during gait in those with Parkinson's disease.

Closed-Loop Deep Brain Stimulation to Treat Medication-Refractory Freezing of Gait in Parkinson's Disease.

Background: Treating medication-refractory freezing of gait (FoG) in Parkinson's disease (PD) remains challenging despite several trials reporting improvements in motor symptoms using subthalamic nucleus or globus pallidus internus (GPi) deep brain stimulation (DBS). Pedunculopontine nucleus (PPN) region DBS has been used for medication-refractory FoG, with mixed findings. FoG, as a paroxysmal phenomenon, provides an ideal framework for the possibility of closed-loop DBS (CL-DBS). Methods: In this clinical trial (NCT02318927), five subjects with medication-refractory FoG underwent bilateral GPi DBS implantation to address levodopa-responsive PD symptoms with open-loop stimulation. Additionally, PPN DBS leads were implanted for CL-DBS to treat FoG. The primary outcome of the study was a 40% improvement in medication-refractory FoG in 60% of subjects at 6 months when "on" PPN CL-DBS. Secondary outcomes included device feasibility to gauge the recruitment potential of this four-lead DBS approach for a potentially larger clinical trial. Safety was judged based on adverse events and explantation rate. Findings: The feasibility of this approach was demonstrated as we recruited five subjects with both "on" and "off" medication freezing. The safety for this population of patients receiving four DBS leads was suboptimal and associated with a high explantation rate of 40%. The primary clinical outcome in three of the five subjects was achieved at 6 months. However, the group analysis of the primary clinical outcome did not reveal any benefit. Interpretation: This study of a human PPN CL-DBS trial in medication-refractory FoG showed feasibility in recruitment, suboptimal safety, and a heterogeneous clinical effect in FoG outcomes.

Differences in PlayerLoad and pitch type in collegiate baseball players.

PlayerLoad is derived from a tri-axial accelerometer device and is a measure of an athlete's external training load. Tri-axial accelerometers (Optimeye S5, Catapult Sports, Melbourne, Australia) were worn by 25 collegiate pitchers during a pitching session. Pitches included fastballs, curve balls, sliders, and changeups. Peak and sum PlayerLoad were calculated for fastballs, curve balls, sliders, and changeups. Statistical analysis included paired t-tests (p < 0.01) and effect size indexes (ESI). Peak and sum PlayerLoad were higher for fastballs compared to changeups (N = 20; ESIpeak = 0.47, p= 0.001 and ESISum = 0.13, p = 0.001, respectively). Peak and sum PlayerLoad were not different comparing fastball to curveball (N = 12; ESIpeak = 0.24, p = 0.050 and ESISum<0.01, p = 0.106) and fastball to slider (N = 12; ESIpeak = 0.32, p = 0.088 and ESISum = 0.02, p = 0.221). Fastball velocity (37.1 ± 2.1 m/s) differed from the changeup (33.8 ± 1.9 m/s; p < 0.001), curveball (32.2 ± 1.2; p < 0.001), and slider (33.8 ± 1.3 m/s; p < 0.001). Pitching workload may differ based on pitch type. Pitch counts may not capture true player fatigue due to variability in stresses resulting from different pitch types.

Coexistent Osteoarthritis and Parkinson's Disease: Data from the Parkinson's Foundation Outcomes Project.

BACKGROUND: The impact of concurrent osteoarthritis on mobility and mortality in individuals with Parkinson's disease is unknown. OBJECTIVE: We sought to understand to what extent osteoarthritis severity influenced mobility across time and how osteoarthritis severity could affect mortality in individuals with Parkinson's disease. METHODS: In a retrospective observational longitudinal study, data from the Parkinson's Foundation Quality Improvement Initiative was analyzed. We included 2,274 persons with Parkinson's disease. The main outcomes were the effects of osteoarthritis severity on functional mobility and mortality. The Timed Up and Go test measured functional mobility performance. Mortality was measured as the osteoarthritis group effect on survival time in years. RESULTS: More individuals with symptomatic osteoarthritis reported at least monthly falls compared to the other groups (14.5% vs. 7.2% without reported osteoarthritis and 8.4% asymptomatic/minimal osteoarthritis, p = 0.0004). The symptomatic group contained significantly more individuals with low functional mobility (TUG≥12 seconds) at baseline (51.5% vs. 29.0% and 36.1%, p < 0.0001). The odds of having low functional mobility for individuals with symptomatic osteoarthritis was 1.63 times compared to those without reported osteoarthritis (p < 0.0004); and was 1.57 times compared to those with asymptomatic/minimal osteoarthritis (p = 0.0026) after controlling pre-specified covariates. Similar results hold at the time of follow-up while changes in functional mobility were not significant across groups, suggesting that osteoarthritis likely does not accelerate the changes in functional mobility across time. Coexisting symptomatic osteoarthritis and Parkinson's disease seem to additively increase the risk of mortality (p = 0.007). CONCLUSION: Our results highlight the impact and potential additive effects of symptomatic osteoarthritis in persons with Parkinson's disease.

Neurophysiological Correlates of Gait in the Human Basal Ganglia and the PPN Region in Parkinson's Disease.

This study aimed to characterize the neurophysiological correlates of gait in the human pedunculopontine nucleus (PPN) region and the globus pallidus internus (GPi) in Parkinson's disease (PD) cohort. Though much is known about the PPN region through animal studies, there are limited physiological recordings from ambulatory humans. The PPN has recently garnered interest as a potential deep brain stimulation (DBS) target for improving gait and freezing of gait (FoG) in PD. We used bidirectional neurostimulators to record from the human PPN region and GPi in a small cohort of severely affected PD subjects with FoG despite optimized dopaminergic medications. Five subjects, with confirmed on-dopaminergic medication FoG, were implanted with bilateral GPi and bilateral PPN region DBS electrodes. Electrophysiological recordings were obtained during various gait tasks for 5 months postoperatively in both the off- and on-medication conditions (obtained during the no stimulation condition). The results revealed suppression of low beta power in the GPi and a 1-8 Hz modulation in the PPN region which correlated with human gait. The PPN feature correlated with walking speed. GPi beta desynchronization and PPN low-frequency synchronization were observed as subjects progressed from rest to ambulatory tasks. Our findings add to our understanding of the neurophysiology underpinning gait and will likely contribute to the development of novel therapies for abnormal gait in PD. Clinical Trial Registration: Clinicaltrials.gov identifier; NCT02318927.

Assessing the Relationship between the Enhanced Gait Variability Index and Falls in Individuals with Parkinson's Disease.

Gait impairment and increased gait variability are common among individuals with Parkinson's disease (PD) and have been associated with increased risk for falls. The development of composite scores has gained interest to aggregate multiple aspects of gait into a single metric. The Enhanced Gait Variability Index (EGVI) was developed to compare an individual's gait variability to the amount of variability in a healthy population, yet the EGVI's individual parts may also provide important information that may be lost in this conversion. We sought to contrast individual gait measures as predictors of fall frequency and the EGVI as a single predictor of fall frequency in individuals with PD. 273 patients (189M, 84F; 68 ± 10 yrs) with idiopathic PD walked over an instrumented walkway and reported fall frequency over three months (never, rarely, monthly, weekly, or daily). The predictive ability of gait velocity, step length, step time, stance time, and single support time and the EGVI was assessed using regression techniques to predict fall frequency. The EGVI explained 15.1% of the variance in fall frequency (p < 0.001, r = 0.389). Although the regression using the combined spatiotemporal measures to predict fall frequency was significant (p=0.002, r = 0.264), none of the components reached significance (gait velocity: p=0.640, step length: p=0.900, step time: p=0.525, stance time: p=0.532, single support time: p=0.480). The EGVI is a better predictor of fall frequency in persons with PD than its individual spatiotemporal components. Patients who fall more frequently have more variable gait, based on the interpretation of the EGVI. While the EGVI provides an objective measure of gait variability with some ability to predict fall frequency, full clinical interpretations and applications are currently unknown.

Gait characterization for patients with orthostatic tremor.

INTRODUCTION: Orthostatic tremor (OT) patients frequently report gait unsteadiness with the advancement of disease; however, there is little understanding of its physiology. We sought to examine in OT, the spatial and temporal characteristics of gait, and the relationship with tremor physiology. METHODS: Gait parameters for OT (n = 16) were recorded with an instrumented Zeno walkway system. All participants complained of gait unsteadiness, especially during slow walking. In a subset of OT, recordings were synchronized with a wireless EMG system for tremor assessment and feet pressure recording. Gait assessments were performed at self-selected habitual, fast, and slow speeds. RESULTS: Compared to data available for an age- and sex-matched healthy controls, OT patients had a significantly reduced step length, increased step width, and increased gait variability (p < 0.0001). Tremor discharges related to OT were consistently recorded across three different speeds of walking. These discharges persisted through all phases of the gait cycle, including the swing phase when the limb was not weight-bearing. The highest tremor amplitude was recorded in the single support phase, followed by double support, and least during the swing phase. CONCLUSION: OT patients have distinct gait abnormalities similar to cerebellar disorders. Tremor discharges from the non-weight bearing leg in the swing phase suggests that muscle contractions, even when occurring without resistance, contribute to OT generation.

A turn for the worse: Turning performance in Parkinson's disease and Essential tremor.

BACKGROUND: Turning is an activity of daily living known to elicit falls in older adults and particularly in persons with movement disorders. Specifically, those with Parkinson's disease have marked impairments in forward walking and turning. Although recent work has identified gait impairment in those with Essential tremor, turning has not been extensively evaluated. As the cerebellum is key in the pathophysiology of Essential tremor, complex tasks like turning, may be impaired for this population. The purpose of this study was to investigate turning behavior and falls in those with Essential tremor and Parkinson's disease. METHODS: 15 persons with Essential tremor and 15 persons with Parkinson's disease performed forward walking and turns on an instrumented walkway. t-tests compared groups and a regression was performed to predict fall frequency. FINDINGS: During turning, those with Essential tremor had lower cadence (p = .042) and took more time (p = .05). No other variables, including forward walking variables, differed between groups. When pooling groups, the significant fall frequency predictor model (p = .003) included decreased forward cadence, increased turning cadence, and female sex. Overall, the model explained 40.7% of the variance. INTERPRETATION: While forward gait performance was similar between groups, those with Essential tremor had increased turn time, a measure often associated with turning impairment. Together, these results suggest overall gait impairment in Essential tremor is more prevalent than recognized. Walking performance, both turning and forward, and sex were predictive of fall frequency. Therapeutic interventions in these populations should include both forward walking and turns to mitigate fall risk.

Persons with essential tremor can adapt to new walking patterns.

Essential tremor (ET) is a common movement disorder that causes motor deficits similar to those seen in cerebellar disorders. These include kinetic tremor, gait ataxia, and impaired motor adaptation. Previous studies of motor adaptation in ET have focused on reaching while the effects of ET on gait adaptation are currently unknown. The purpose of this study was to contrast locomotor adaptation in persons with and without ET. We hypothesized that persons with ET would show impaired gait adaptation. In a cross-sectional study, persons with ET (n = 14) and healthy matched controls (n = 12) walked on a split-belt treadmill. Participants walked with the belts moving at a 2:1 ratio, followed by overground walking to test transfer, followed by a readaptation period and finally a deadaptation period. Step length asymmetry was measured to assess the rate of adaptation, amount of transfer, and rates of readaptation and deadaptation. Spatial, temporal, and velocity contributions to step length asymmetry were analyzed during adaptation. There were no group by condition interactions in step length asymmetry or contributions to step length asymmetry. Regardless of condition, persons with ET walked slower and exhibited lower temporal (P < 0.001) and velocity (P = 0.001) contributions to step length asymmetry than controls. Persons with ET demonstrated a preserved ability to adapt to, store, and transfer a new walking pattern. Despite probable cerebellar involvement in ET, locomotor adaptation is an available mechanism to teach persons with ET new gait patterns.NEW & NOTEWORTHY This study is the first to investigate walking adaptation abilities of people with essential tremor. Despite evidence of cerebellar impairment in this population, people with essential tremor can adapt their walking patterns. However, people with essential tremor do not modulate the timing of their footsteps to meet walking demands. Therefore, this study is the first to report impairments in the temporal aspects of walking in people with essential tremor during both typical and locomotor learning.

The Primary Gait Screen in Parkinson's disease: Comparison to standardized measures.

BACKGROUND: Persons with Parkinson's disease exhibit gait deficits during comfortable-pace overground walking and data from pressure sensitive mats have been used to quantify gait performance. The Primary Gait Screen is a new assessment which includes gait initiation, overground walking, turning, and gait termination. Although overground assessments are useful, the Primary Gait Screen offers a more complex evaluation than traditional gait assessments. RESEARCH QUESTION: Is the overground walking portion of the Primary Gait Screen comparable to traditional gait assessments? METHODS: Persons with Parkinson's disease (N = 175; 47 F, 128 M; 67 ±â€¯9 yrs) prospectively completed 4 passes at a self-selected speed and two trials of the Primary Gait Screen on an 8 m long pressure-sensing mat. Spatiotemporal gait variables were computed and a repeated-measures MANOVA with a Bonferroni correction compared the spatiotemporal variables from the Primary Gait Screen to the self-selected trials: gait velocity, cadence, step length, step time, and stride length. RESULTS: The analyses failed to detect differences between the Primary Gait Screen and self-selected trials for gait velocity, step length, or stride length (p > .01). Post-hoc tests revealed decreased cadence and increased step time were the only differences between the Primary Gait Screen trials and the self-selected trial (p < .001). SIGNIFICANCE: Differences seen in cadence and step time during the Primary Gait Screen may be attributed to patients' strategy, but are likely not clinically meaningful. The Primary Gait Screen appears to be a comparable assessment of overground walking in persons with Parkinson's disease, and may be a useful and accurate clinical assessment of walking.

THE RELATIONSHIP BETWEEN TRUNK ROTATION, UPPER QUARTER DYNAMIC STABILITY, AND THE KERLAN-JOBE ORTHOPAEDIC CLINIC OVERHEAD ATHLETE SHOULDER AND ELBOW SCORE IN DIVISION I COLLEGIATE PITCHERS.

HYPOTHESIS/PURPOSE: The purpose of this study was to assess relationships between active trunk rotation range of motion (TROM), upper quarter dynamic stability, and composite and individual item KJOC scores in collegiate baseball pitchers. A secondary purpose was to determine whether differences exist between baseball pitchers with and without an injury history in terms of their performance on TROM, upper quarter dynamic stability, and composite and individual KJOC scores. It was hypothesized that increased TROM and upper quarter dynamic stability are associated with better (higher) KJOC scores and pitchers with an injury history would exhibit lower KJOC scores compared to uninjured pitchers. STUDY DESIGN: Cross-sectional Cohort Study. METHODS: Thirty-six college pitchers were assessed for TROM, performance on the Upper Quarter Y-Balance Test (YBT-UQ) and they also completed the KJOC. Subjects were grouped based on previous injury history: injured, required surgery, (IS, n=9), injured, no surgery, (INS, n=6), and uninjured (UI, n=21). Pearson's Correlations were used to assess relationships between clinical measurements and the KJOC. One-way ANOVAs were used to assess differences in TROM, YBT-UQ, and KJOC scores between groups (P<0.05). RESULTS: No significant relationships were detected between TROM measures and KJOC composite scores (throwing arm: r = .239, p = 0.16; non-throwing arm: r=.291, p = 0.09). A moderate relationship was found between the YBT-UQ and the KJOC scores (throwing arm: r = .413, p = 0.01; non-throwing arm: r=.380, p = 0.02). The mean KJOC scores for item 1 (warm-up limitations) were significantly different between all three groups (IS: 6.7, INS: 9.7, UI: 9.1; p = 0.015). Mean scores on item 5 (strain on relationships with coaches) and item 8 (limitations in competition endurance) were significantly different between the IS and UI groups (Item 5 = IS: 7.8, UI: 9.5, p = 0.02; Item 8=IS: 6.4, UI: 8.8, p = 0.04). CONCLUSION: A positive moderate association was found between upper quarter dynamic stability as measured by the YBT-UQ and the KJOC. Pitchers with no surgical history had better KJOC scores for warm up time, competitive endurance, and impact on team relationships. LEVEL OF EVIDENCE: 3.

The Relationship Between Trunk Rotation, Upper Quarter Dynamic Stability, and Pitch Velocity.

Bullock, GS, Schmitt, AC, Chasse, PM, Little, BA, Diehl, LH, and Butler, RJ. The relationship between trunk rotation, upper quarter dynamic stability, and pitch velocity. J Strength Cond Res 32(1): 261-266, 2018-Understanding the relationship between upper quarter mobility, dynamic stability, and pitching velocity may be beneficial in elucidating underlying factors that affect pitching performance. The purpose of this study was to investigate upper trunk rotation mobility and upper quarter dynamic stability and their correlation to pitch velocity in NCAA Division I collegiate pitchers. We hypothesized that collegiate pitchers with greater upper trunk rotation mobility and upper extremity dynamic stability would exhibit higher pitching velocity. Trunk rotation and the Upper Quarter Y-Balance Test (YBT-UQ) were measured using standardized protocols. Collegiate pitchers (N = 30) then proceeded to complete their team prescribed dynamic and throwing warm-up followed by a pitching session from regulation distance at 100% effort. Each pitch was recorded for velocity and pitch type, only fastballs were used in analysis. The relationships between trunk rotation and fastball velocity, and YBT-UQ scores and fastball velocity were assessed using a series of 2-tail Pearson's correlations (p < 0.05). Throwing and nonthrowing sides (69.6 ± 9.5°, 70.7 ± 9.4°) had similar trunk rotation mobility. No statistically significant correlation between upper trunk rotation mobility and pitch velocity was found (throwing arm: r = 0.131; p < 0.491; nonthrowing arm: r = 0.135; p < 0.478). There was also no correlation between the YBT-UQ and fastball velocity. In this study of Division I baseball pitchers, we found no relationship between trunk rotational mobility, upper quarter dynamic stability, and pitching velocity. This suggests that increased upper extremity stability and trunk mobility are not directly related to fastball velocity. Understanding factors that associate to velocity may be helpful in predicting pitching performance.

Comparison of posture and balance in cancer survivors and age-matched controls.

BACKGROUND: The combination of peripheral neuropathy and other treatment-associated side effects is likely related to an increased incidence of falls in cancer survivors. The purpose of this study was to quantify differences in postural stability between healthy age-matched controls and cancer survivors. METHODS: Quiet standing under four conditions (eyes open/closed, rigid/compliant surface) was assessed in 34 cancer survivors (2 males, 32 females; age: 54(13) yrs., height: 1.62(0.07) m; mass: 78.5(19.5) kg) and 34 age-matched controls (5 males, 29 females; age: 54(15) yrs.; height: 1.62(0.08) m; mass: 72.8(21.1) kg). Center of pressure data were collected for 30s and the trajectories were analyzed (100Hz). Three-factor (group*surface*vision) mixed model MANOVAs with repeated measures were used to determine the effect of vision and surface on postural steadiness between groups. FINDINGS: Cancer survivors exhibited larger mediolateral root-mean square distance and velocity of the center of pressure, as well as increased 95% confidence ellipse area (P<0.01) when compared with their age-matched counterparts. For example, when removing visual input, cancer survivors had an average increase in 95% confidence ellipse area of 91.8mm2 while standing on a rigid surface compared to a 68.6mm2 increase for the control group. No frequency-based center of pressure measures differed between groups. INTERPRETATION: Cancer survivors exhibit decreased postural steadiness when compared with age-matched controls. For cancer survivors undergoing rehabilitation focused on existing balance deficits, a small subset of the center of pressure measures presented here can be used to track progress throughout the intervention and potentially mitigate fall risk.

KINEMATIC AND KINETIC VARIABLES DIFFER BETWEEN KETTLEBELL SWING STYLES.

BACKGROUND: Kettlebell (KB) and indian club swings (ICS) are used diversely for developing strength and power. It has been proposed that multiple swing techniques can be used interchangeably to elicit similar adaptations within performance training. Hypothesis/Purpose: It was hypothesized that there will be not be a difference in peak joint angles between types of swings. Furthermore, given the nature of the overhead kettlebell swing (OKS), it was hypothesized that the OKS will be associated with a greater cycle time and a greater vertical impulse compared to shoulder height swing (SKS) and ICS. The purpose of this study was to analyze the kinematics and kinetics of the SKS, OKS, and ICS. STUDY DESIGN: Cross-sectional cohort. METHODS: Fifteen healthy subjects underwent 3D biomechanical analysis for assessment of kinematic and kinetic data. Subjects performed two trials of ten repetitions at full effort for each swing in a randomized order using either a standard set of 0.45 kg indian clubs or sex specific KB loads (Female = 12kg, Male = 20kg). Lower extremity sagittal plane kinematics and kinetics were analyzed for peak values during the down and up portions of the swing patterns. Statistical analyses were carried out utilizing one-way ANOVAs (p<.05) and effect size indices. RESULTS: Cycle time for the OKS was 34% longer than the SKS and ICS (p<.001; ESISKS = 2.09, ESIICS=1.92). In general, ankle (SKS: 0.82 ± 0.16; OKS: 0.90 ± 0.21; ICS: 0.60 ± 0.15 BW*BH) and hip joint moments (SKS: 2.34 ± 0.68; OKS: 2.32 ± 0.53; ICS: 1.84 ± 0.47 BW*BH) and joint powers, along with peak vertical ground reaction forces (vGRF) (SKS: 0.98 ± 0.14; OKS: 0.96 ± 0.10; ICS: 0.86 ± 0.11 BW/s), were higher in the SKS and OKS than the ICS (p<.001; ankle: ESISKS/OKS=0.43, ESISKS/ICS=1.42; hip: ESISKS/OKS=0.03, ESISKS/ICS=0.87; vGRF: ESISKS/OKS=1.80, ESISKS/ICS=0.20). There were no observed differences found in peak joint angles between the movements. CONCLUSION: Although these swings are kinematically similar, the differing kinetic demands of these exercises may be important in selecting the right training modality for specific strength and power training. LEVEL OF EVIDENCE: 2.