We propose that learning proper hitting kinematics should be encouraged at a young age during youth baseball because this may help reinforce proper hitting kinematics as a player progresses to higher levels of baseball in their adult years. To enhance our understanding between youth and adult baseball hitting, kinematic and temporal analyses of baseball hitting were evaluated with a high-speed motion analysis system between 12 skilled youth and 12 skilled adult baseball players. There were only a small number of temporal differences between youth and adult hitters, with adult hitters taking significantly greater time than youth hitters during the stride phase and during the swing. Compared with youth hitters, adult hitters a) had significantly greater (p < .01) lead knee flexion when the hands started to move forward; b) flexed the lead knee over a greater range of motion during the transition phase (31° versus 13°); c) extended the lead knee over a greater range of motion during the bat acceleration phase (59° versus 32°); d) maintained a more open pelvis position at lead foot off ground; and e) maintained a more open upper torso position when the hands started to move forward and a more closed upper torso position at bat-ball contact. Moreover, adult hitters had greater peak upper torso angular velocity (857°/s versus 717°/s), peak left elbow extension angular velocity (752°/s versus 598°/s), peak left knee extension angular velocity (386°/s versus 303°/s), and bat linear velocity at bat-ball contact (30 m/s versus 25 m/s). The numerous differences in kinematic and temporal parameters between youth and adult hitters suggest that hitting mechanics are different between these two groups.

A motion system collected 120-Hz data from 14 baseball adult hitters using normal and choke-up bat grips. Six swings were digitized for each hitter, and temporal and kinematic parameters were calculated. Compared with a normal grip, the choke-up grip resulted in 1) less time during stride phase and swing; 2) the upper torso more opened at lead foot contact; 3) the pelvis more closed and less bat linear velocity at bat-ball contact; 4) less range of motion of the upper torso and pelvis during swing; 5) greater elbow flexion at lead foot contact; and 6) greater peak right elbow extension angular velocity. The decreased time during the stride phase when using a choke-up grip implies that hitters quicken their stride when they choke up. Less swing time duration and less upper torso and pelvis rotation range of motion using the choke-up grip supports the belief of many coaches and players that using a choke-up grip results in a "quicker" swing. However, the belief that using a choke-up grip leads to a faster moving bat was not supported by the results of this study.Escamilla is with the

Background and Purpose. A primary outcome of concern to the California State University, Sacramento physical therapy program is the ability of graduates to pass the National Physical Therapy Examination (NPTE) for licensure. The purpose of this case study was to identify the predictive strength of preadmission demographic factors, academic performance, and standardized test scores in graduates' ability to pass the NPTE. Case Description. Preadmission data from 11 years of graduates from a single Master of Physical Therapy (MPT) program (n = 320) were analyzed, including prerequisite grade point average (pGPA), analytic Graduate Record Examination (GRE), verbal GRE and quantitative GRE (qGRE) scores, sex, English as a second language (ESL) status, and NPTE test results. The bivariate association of each preadmission variable to NPTE success was assessed, and receiver operating characteristic curve analysis was performed to determine the optimal cutoff score of each continuous variable. Multifactor logistic regression analysis was performed to determine which independent variables were most predictive of NPTE success. Outcomes. Of the 320 MPT graduates, 284 (88.7%) passed the NPTE on the first attempt and 305 (95.3%) passed on the first or second attempt. Of all MPT graduates, 182 (57%) were females, and 57 (18%) reported that English was their second language. All three of the GRE subscale average scores, pGPA, and ESL were significantly associated with NPTE outcomes. Persons with ESL were significantly more likely to need more than one attempt to pass the NPTE. The qGRE score was found to be the strongest predictor of NPTE outcomes in the multifactor logistic regression analysis, whether looking at first-time passing rates or second-time pass rates. Discussion and Conclusion. The strongest preadmission variable for NPTE success was the qGRE score of ≥29th percentile, and this cutoff score explained the variance predicted by ESL and pGPA. The admission committee used this data to implement an evidence-based admission's minimum threshold for qGRE. This case is an example of how a physical therapist education program can analyze its own data to apply evidence to its admission criteria that best serve the mission of the program.

BackgroundStudies have shown a consistent association between exposure to traffic-related air pollution and adverse health effects. In particular, exposure can be high for cyclists who travel near roadways. The objective of the current study was to examine the relationship between short-term exposure of near-road traffic emissions and acute changes in lung function among individuals who frequently bike in the Sacramento and Davis areas in California. Ultrafine particulate matter (UFPM) was used as a surrogate for near-roadway exposure in this study since the main source of this pollutant is from motor vehicle exhaust.MethodsThirty-two bicyclists were recruited and completed two rides on separate days during the study period of March-June, 2008. One ride was on a high traffic route paralleling a section of Interstate 80 (I-80)/Interstate Business 80 (I-80B), and a second one was on a low traffic route, such as bike paths away from major highways. The participant’s lung function was measured before and after each ride, and UFPM exposure was measured during the rides using a condensation particle counter (CPC).ResultsIn the final linear mixed-effect model using median UFPM concentrations as the main exposure, we observed that lung function change (post–ride minus baseline measurements) shifted in the negative direction. Lung function changed by 216 mL for FVC and 168 mL for FEV1, respectively, for an interquartile range (IQR: 12,225 to 36,833 number of particles/cm3) increase of UFPM concentration after adjusting for other covariates of age, sex, wind direction, and day of the week.ConclusionsThis study found significant associations between increased levels of UFPM concentrations as a proxy for near road traffic pollution, and decrements in lung function measurements. Our results are related to short-term exposures, and the long-term health effects of cycling near heavy traffic require further research. Our study suggests the need to reduce traffic pollution, particularly near roads. Cyclists should plan their route to reduce their exposure where possible and further research on built environment designs may help urban planners to reduce the potential health concerns of cyclists’ exposure to traffic-related air pollution.Electronic supplementary materialThe online version of this article (doi:10.1186/s12940-017-0212-x) contains supplementary material, which is available to authorized users.

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