Effects of synthetic turf and shock pad on impact attenuation related biomechanics during drop landing.

Adding a shock pad as an underlayment to synthetic turf aims to improve attenuation of impact forces. The purpose of this research was to investigate effects of an infilled synthetic turf with three different shock pads on impact attenuation related biomechanics of lower extremity during the drop landing. Twelve active and healthy recreational male athletes performed 60 cm drop landing with a controlled landing technique on five surface conditions: a baseline surface (force platform), an infilled synthetic turf surface, turf plus foam shock pad, turf plus a low-density shock pad, and turf plus a high-density shock pad. Furthermore, a mechanical impact test was conducted (ASTM F355). Turf plus foam shock pad, turf plus low-density shock pad, and turf plus high-density shock pad all resulted in significantly lower 1st vertical peak ground reaction force (13.3%, 13.3%, and 12.7% reductions, respectively) and loading rate (20.4%, 25.4%, and 21.1% reductions, respectively) compared to baseline surface. Significantly greater trunk extension moment was found on turf plus low-density shock pad compared to turf surface (21.2%) and turf plus foam shock pad (12.0%). These results suggest that synthetic turf plus shock pad surfaces provide improved impact attenuation compared to baseline surface in the early landing phase.

Force-limiting and the mechanical response of natural turfgrass used in the National Football League: A step toward the elimination of differential lower limb injury risk on synthetic turf.

Lower limb injury rate in the National Football League (NFL) is greater on synthetic turf than on natural turfgrass. Foot loading in potentially injurious situations can be mitigated by damage to natural turfgrass that limits the peak load by allowing relative motion between the foot and the ground. Synthetic turf surfaces do not typically sustain such damage and thus lack such a load-limiting mechanism. To guide innovation in synthetic turf design, this paper reports 1) the peak loads of natural turfgrass when loaded by a cleated footform and 2) corridors that define the load-displacement response. Kentucky bluegrass [Poa pratensis, L.] and two cultivars of hybrid bermudagrass [Cynodon dactylon (L.) Pers × C. transvaalensis Burtt Davy] were tested with two cleat patterns in three loading modes (anterior-posterior or AP translation, medial-lateral or ML translation, and forefoot external rotation) at two power levels (full-power, which generated potentially injurious loads, and reduced-power, which generated horizontal forces similar to non-injurious ground reaction forces applied by an elite athlete during play). All tests generated peak force<4.95 kN and torque<173 Nm, which is in a loading regime that would be expected to mitigate injury risk. In full-power tests, bermudagrass withstood significantly (p < 0.05) greater peak loads than Kentucky bluegrass: (3.86 ± 0.45 kN vs. 2.66 ± 0.23 kN in AP, 3.25 ± 0.45 kN vs. 2.49 ± 0.36 kN in ML, and 144.8 ± 12.0 Nm vs. 126.3 ± 6.1 Nm in rotation). Corridors are reported that describe the load-displacement response aggregated across all surfaces tested.

Cytochrome P450 Inhibitors Reduce Creeping Bentgrass (Agrostis stolonifera) Tolerance to Topramezone.

Creeping bentgrass (Agrostis stolonifera L.) is moderately tolerant to the p-hydroxyphenylpyruvate dioxygenase-inhibiting herbicide topramezone. However, the contribution of plant metabolism of topramezone to this tolerance is unknown. Experiments were conducted to determine if known cytochrome P450 monooxygenase inhibitors 1-aminobenzotriazole (ABT) and malathion alone or in combination with the herbicide safener cloquintocet-mexyl influence creeping bentgrass tolerance to topramezone. Creeping bentgrass in hydroponic culture was treated with ABT (70 µM), malathion (70 µm and 1000 g ha(-1)), or cloquintocet-mexyl (70 µM and 1000 g ha(-1)) prior to topramezone (8 g ha(-1)) application. Topramezone-induced injury to creeping bentgrass increased from 22% when applied alone to 79 and 41% when applied with malathion or ABT, respectively. Cloquintocet-mexyl (70 µM and 1000 g ha(-1)) reduced topramezone injury to 1% and increased creeping bentgrass biomass and PSII quantum yield. Cloquintocet-mexyl mitigated the synergistic effects of ABT more than those of malathion. The effects of malathion on topramezone injury were supported by creeping bentgrass biomass responses. Responses to ABT and malathion suggest that creeping bentgrass tolerance to topramezone is influenced by cytochrome P450-catalyzed metabolism. Future research should elucidate primary topramezone metabolites and determine the contribution of cytochrome P450 monooxygenases and glutathione S-transferases to metabolite formation in safened and non-safened creeping bentgrass.

Effects of Two Football Stud Types on Knee and Ankle Kinetics of Single-Leg Land-Cut and 180° Cut Movements on Infilled Synthetic Turf.

Higher ACL injury rates have been recorded in cleats with higher torsional resistance in American football, which warrants better understanding of shoe/stud-dependent joint kinetics. The purpose of this study was to determine differences in knee and ankle kinetics during single-leg land cuts and 180° cuts on synthetic infilled turf while wearing 3 types of shoes. Fourteen recreational football players performed single-leg land cuts and 180° cuts in nonstudded running shoes (RS) and in football shoes with natural (NTS) and synthetic turf studs (STS). Knee and ankle kinetic variables were analyzed with a 3 × 2 (shoe × movement) repeated-measures ANOVA (P < .05). A significant shoe-by-movement interaction was found in loading response peak knee adduction moments, with NTS producing smaller moments compared with both STS and RS only in 180° cuts. Reduced peak negative plantar flexor powers were also found in NTS compared with STS. The single-leg land cut produced greater loading response and push-off peak knee extensor moments, as well as peak negative and positive extensor and plantar flexor powers, but smaller loading peak knee adduction moments and push-off peak ankle eversion moments than 180° cuts. Overall, the STS and 180° cuts resulted in greater frontal plane knee loading and should be monitored for possible increased ACL injury risks.

Effects of two football stud configurations on biomechanical characteristics of single-leg landing and cutting movements on infilled synthetic turf.

Multiple playing surfaces and footwear used in American football warrant a better understanding of relationship between different combinations of turf and footwear. The purpose of this study was to examine effects of shoe and stud types on ground reaction force (GRF) and ankle and knee kinematics of a 180° cut and a single-leg 90° land-cut on synthetic turf. Fourteen recreational football players performed five trials of the 180° cut and 90° land-cut in three shoe conditions: non-studded running shoe, and football shoe with natural and synthetic turf studs. Variables were analyzed with a 3 × 2 (shoe × movement) repeated measures analysis of variance (p < 0.05). Peak vertical GRF (p < 0.001) and loading rate (p < 0.001) were greater during 90° land-cut than 180° cut. For 180° cut, natural turf studs produced smaller peak medial GRFs compared to synthetic turf studs and non-studded shoe (p = 0.012). For land-cut, peak eversion velocity was reduced in running shoes compared to natural (p = 0.016) and synthetic (p = 0.002) turf studs. The 90° land-cut movement resulted in greater peak vertical GRF and loading rate compared to the 180° cut. Overall, increased GRFs in the 90° land-cut movement may increase the chance of injury.

Effects of mesotrione on perennial ryegrass (Lolium perenne L.) carotenoid concentrations under varying environmental conditions.

Mesotrione is a carotenoid biosynthesis inhibiting herbicide, which is being evaluated for use in turfgrass. Carotenoids are important light harvesting and photoprotecting pigments that dissipate and quench excess light energy. The effects of mesotrione on carotenoid concentrations in turf and weed species, such as perennial ryegrass (Lolium perenne L.), are poorly understood. Mesotrione injury to perennial ryegrass has been reported, and symptomology may differ due to postapplication environmental factors such as irradiance and temperature. Research was conducted to investigate the effects of mesotrione on perennial ryegrass under varying irradiance (600, 1100, or 1600 micromol/m (2)/s) at three different temperatures (18, 26, and 34 degrees C). Postapplication irradiance and temperature levels did not affect visual injury symptoms in perennial ryegrass. Bleaching of treated plants was highest 7 days after treatment (DAT; 8%) and recovered to nontreated levels by 21 DAT. Mesotrione applications did not decrease perennial ryegrass foliar biomass accumulations. Carotenoid concentrations of nontreated plants were similar to those reported in creeping bentgrass and many green leafy vegetable crops. However, chlorophyll a and b, beta-carotene, lutein, and violaxanthin concentrations decreased due to mesotrione applications, while phytoene and zeaxanthin, a photoprotecting carotenoid, increased. The photochemical efficiency (F v/ F m) of treated plants was lower than nontreated plants at 3 and 7 DAT; however, treated plants recovered to nontreated levels 21 DAT. Results indicate that postapplication irradiance and temperature levels may not affect mesotrione efficacy in perennial ryegrass. Preferential accumulation of zeaxanthin following mesotrione applications may be a stress-related response, which may reduce light harvesting complex size and directly quench excess light energy.