Effects of Rosin Powder Application on the Frictional Behavior Between a Finger Pad and Baseball

A Retrospective Analysis of Major League Baseball Hit-by-Pitch Rates before and after the Crackdown on Foreign Substance Use

OBJECTIVE

Determine whether there was an increased incidence of hit-by-pitch events in Major League Baseball (MLB) following the decision to enforce the foreign substance ban for pitchers during the 2021 season.

DESIGN

Descriptive Epidemiological Study.

SETTING

Major League Baseball hit-by-pitch data from publicly available Web sites ( mlb.com and fangraphs.com ).

PARTICIPANTS

Major League Baseball players during the 2017, 2018, 2019, 2021, and 2022 seasons.

INDEPENDENT VARIABLES

Hit-by-pitch exposure data by season and individual pitch type.

MAIN OUTCOME MEASURES

Hit-by-pitch incidence rates from the 2017 to 2019 seasons (preenforcement) and the 2021 to 2022 seasons (postenforcement). Rates were compared with incidence rate ratios (IRRs).

RESULTS

Hit-by-pitch incidence rate increased from 2.66 to 3.06 per 1000 total pitches (IRR, 1.15 [95% CI, 1.08-1.23]; P < 0.0001) following the enforcement. Incidence rates for 2017, 2018, and 2019 did not differ from each other individually, but incidence rate of all 3 seasons individually were significantly lower than that for the 2021 season ( P < 0.005). Sliders were 29% more likely to hit batters following the enforcement ( P = 0.0015).

CONCLUSIONS

Major League Baseball batters were hit by pitches at a significantly higher rate following the league's crackdown on foreign substance use for the 2021 seasons compared with the same time of year during the 2017 to 2019 seasons. This was followed by a slight regression toward preenforcement levels during the 2022 season.

Estimation of tangential finger force and its relationship with the spin rate of pitched fastball

This study had two objectives: (a) estimating the force exerted by pitchers in generating the spin of a fastball and (b) examining the factors that influence the spin rate of a fastball. Thirteen baseball pitchers participated in this study. The resultant forces acting on the ball was measured using an accelerometer placed in the baseball, and the force was decomposed into two frequency components using maximal overlap discrete wavelet transform. The intraclass correlation coefficients (ICC) between the integration of the high-frequency component of acceleration and the variation in the tangential velocity was high (ICC(3,1) = 0.64 ± 0.16). The ball spin per velocity (SPV) was significantly correlated with the peak value of the high-frequency component of the resultant forces (r = 0.66, p < 0.01). The high-frequency component of the resultant forces reflected the force in the tangential direction, and this force was one of the factors that adjusted the ball spin rate. The SPV did not significantly correlate with the peak value of the low-frequency component of the resultant forces (r = 0.50, p > 0.05). This indicates that decomposing the resultant forces into two frequency components is necessary to investigate the function of the finger during pitching.

Finger friction with leather and seam of new and used softballs with and without rosin powder

The purpose of this study was to investigate the friction of finger against polyurethane-coated leather and seam surfaces of new and used softballs. The effects of seam alignment (across and along the seam) and chalk/rosin powder application were also investigated. The coefficient of static friction (COF) was evaluated on 14 college female softball players who rubbed the pad of their index finger on a test surface fixed on a biaxial force plate. The mean COF of the new leather was 1.04, and those of the seam were 1.16 for the across condition, and 1.07 for the along condition. The leather-seam difference in COF was significant. The used ball's leather and seam had lower COF than those of the new ball. The seam alignment difference did not reach the level of significance. For both new and used balls, the application of chalk/rosin powder to the finger reduced COF, and the reduction was greater on the leather than on the seam. It was concluded that the outer cover of softballs, and especially the seam portions, is equipped with reasonably high friction under natural finger condition. The friction is reduced in used balls and with the use of chalk/rosin powder.

A review of advances in tribology in 2020–2021

Around 1,000 peer-reviewed papers were selected from 3,450 articles published during 2020–2021, and reviewed as the representative advances in tribology research worldwide. The survey highlights the development in lubrication, wear and surface engineering, biotribology, high temperature tribology, and computational tribology, providing a show window of the achievements of recent fundamental and application researches in the field of tribology.