Kinematic, Kinetic, and Temporal Metrics Associated With Golf Proficiency.

ABSTRACT: McHugh, MP, O'Mahoney, CA, Orishimo, KF, Kremenic, IJ, and Nicholas, SJ. Kinematic, kinetic, and temporal metrics associated with golf proficiency. J Strength Cond Res 38(3): 599-606, 2024-The biomechanics of the golf swing have been studied extensively, but the literature is unclear on which metrics are indicative of proficiency. The purpose of this study was to determine which metrics identified golf proficiency. It was hypothesized that discrete kinematic, kinetic, and temporal metrics would vary depending on proficiency and that combinations of metrics from each category would explain specific proficiency metrics. Kinematic, kinetic, and temporal metrics and their sequencing were collected for shots performed with a driver in 33 male golfers categorized as proficient, average, or unskilled (based on a combination of handicap, ball velocity, and driving distance). Kinematic data were collected with high-speed motion analysis, and ground reaction forces (GRF) were collected from dual force plates. Proficient golfers had greater x-factor at ball impact and greater trunk deceleration before ball impact compared with average ( p < 0.05) and unskilled ( p < 0.01) golfers. Unskilled golfers had lower x-factor at the top of the back swing and lower peak x-factor, and they took longer to reach peak trunk velocity and peak lead foot GRF compared with average ( p < 0.05) and proficient ( p < 0.05) golfers. A combination of 2 kinematic metrics (x-factor at ball impact and peak pelvis velocity), 1 kinetic metric (peak lead foot GRF), and 2 timing metrics (the timing of peak trunk and arm velocity) explained 85% of the variability in ball velocity. The finding that x-factor at ball impact and trunk deceleration identified golf proficiency points to the potential for axial trunk rotation training to improve performance.

AFM Force Mapping Elucidates Pilus Deployment and Key Lifestyle-Dependent Surface Properties in Bdellovibrio bacteriovorus.

Bdellovibrio bacteriovorus is known for predation of a wide variety of Gram-negative bacteria, making it of interest as an alternative or supplement to chemical antibiotics. However, a fraction of B. bacteriovorus follows a nonpredatory, "host-independent" (HI) life cycle. In this study, live predatory and HI B. bacteriovorus were captured on a surface and examined, in buffer, by collecting force maps using atomic force microscopy (AFM). The approach curves obtained on HI cells are similar to those on other Gram-negative cells, with a short nonlinear region followed by a linear region. In contrast, the approach curves obtained on predatory cells have a large nonlinear region, reflecting the unusual flexibility of the predatory cell. As the AFM tip is retracted, it shows virtually no adhesion to predatory B. bacteriovorus but has multiple adhesion events on HI cells and the 200-500+ nm region immediately surrounding them. Measured pull-off forces, pull-off distances, and effective spring constants are consistent with the multiple stretching events of Type IV pili, both on and especially adjacent to the cells. Exposure of the HI B. bacteriovorus to a pH-neutral 10% cranberry juice solution, which contains type A proanthocyanidins that are known to interfere with the adhesion of multiple types of pili, results in a substantial reduction in adhesion. Type IV pili are required for successful predation by B. bacteriovorus, but pili used in the predation process are located at the non-flagellated pole of the cell and can retract when not in use. Such pili are rarely observed under the conditions of this study, where the predator has not encountered a prey cell. In contrast, HI cells appear to have many pili distributed on and around the whole cell, presumably ready to be utilized for a variety of HI cell activities including attachment to surfaces.

Importance of Transverse Plane Flexibility for Proficiency in Golf.

ABSTRACT: McHugh, MP, O'Mahoney, CA, Orishimo, KF, Kremenic, IJ, and Nicholas, SJ. Importance of transverse plane flexibility for proficiency in golf. J Strength Cond Res 36(2): e49-e54, 2022-The extent to which the flexibility requirements for golf proficiency vary between the planes of motion has not been examined. The purpose of this study was to compare flexibility between proficient and average golfers with the hypothesis that proficient golfers have greater transverse plane flexibility than average golfers, with no differences in the sagittal and frontal planes. Twenty-five male golfers were categorized as proficient (handicap ≤5, n = 13) or average (handicap 10-20, n = 12). Fourteen flexibility tests were performed (4 shoulder tests, 4 trunk tests, and 6 hip tests) with tests in all 3 planes of motion for each body segment. In addition, trunk motion, pelvic motion, and hip motion during the golf swing were assessed with high-speed motion analysis. Ball speed and shot distance were recorded with a golf simulator. Proficient golfers had significantly better flexibility than average golfers in the transverse plane (shoulder p = 0.021, trunk p = 0.003, and hip p < 0.0001), with no differences in the sagittal plane or frontal plane (plane of motion by golf proficiency p = 0.0001). Transverse plane hip flexibility accounted for 48% of the variability in ball speed (p < 0.0001) and 45% of the variability in total distance (p = 0.001). During the golf swing, proficient golfers had greater separation between the pelvis and the trunk (x-factor) than average golfers (p = 0.002). In conclusion, transverse plane flexibility in the trunk and hips is an important requirement for golf proficiency. Sagittal plane flexibility and frontal plane flexibility were unrelated to proficiency. Developing and maintaining trunk and hip rotation flexibility is important for optimizing performance.