"Tibial acceleration peaks and integrals on three different surfaces during M-Drill." Footwear Science, 15(sup1), pp. S134–S135Keywords: Surface interactionbiomechanicsinertial measurement unitsimpact attenuationaccelerationlower extremity Disclosure statementNo potential conflict of interest was reported by the author(s).Tibial acceleration peaks and integrals on three different surfaces during M-DrillAll authorsSean A. Brown, Joshua M. Lardie, Jake A. Melaro, Kyley H. Dickson, John C. Sorochan & Joshua T. Weinhandl https://doi.org/10.1080/19424280.2023.2199399Published online:30 June 2023Table 1. Peak tibial acceleration (m/s/s) and tibial acceleration integral: Mean ± STD. Download CSVDisplay Table

Zoysiagrasses (Zoysia spp. Willd.) have been predominately used as turfgrass for residential and commercial lawns in addition to golf course fairways and tees due to reduced input requirements compared with bermudagrass (Cynodon spp.). The recent development of fine-textured zoysiagrass cultivars has sparked interest in using zoysiagrass on putting greens. A complete-factorial field experiment was conducted over replicate trials in Knoxville, TN to evaluate the putting green performance and quality of four zoysiagrass cultivars under two nitrogen (N) rates in the transition zone. Four zoysiagrass cultivars (Lazer, M85, Prizm, and Trinity) were treated with either 0.93 or 1.9 g N m(-2) every 2 wk over a 16-wk period from June to September in 2020 and 2021. Ball roll distance, surface firmness, and turfgrass color were evaluated weekly. Lazer and M85 consistently provided the greatest ball roll distance and turfgrass color over both seasons, whereas Prizm occasionally exhibited similar performance and color. Lazer produced the firmest greens, whereas Prizm exhibited the softest surface. Trinity had reduced turfgrass color over both years, implying that it should not be used on putting surfaces. The 1.9 g N m(-2) rate reduced ball roll distance and increased turfgrass color but had limited effect on surface firmness. Applying 0.93 g N m(-2) increased ball roll distance, reduced turfgrass color, and maintained surface firmness similar to 1.9 g N m(-2). Additionally, cultivar selection will likely affect putting green performance, playability, and quality.

The use of hybrid turf systems is very common in Europe and is increasing in popularity in the United States. Little research was found on the impact of stitched hybrid systems on hybrid bermudagrass ‘NorthBridge’ ( Cynodon dactylon (L.) Pers. × C. Transvaalensis Burtt Davy) athletic fields. A study was conducted to determine the impact of stitched hybrid systems on hybrid bermudagrass performance at the University of Tennessee Center for Athletic Field Safety in Knoxville, TN USA in the fall of 2018 and 2019. A randomized complete block design with four replications was utilized. The study treatments consisted of synthetic fibers spacing stitched in 2 cm by 2 cm, 2 cm by 4 cm treatments, and an untreated control. Each plot received 30 games of simulated traffic events with 12 test variables collected including: percent green cover, surface hardness, head impact criteria, ball rebound, ball roll, angled ball rebound, vertical deformation, energy restitution, force reduction, surface temperature, and rotational and horizontal traction. Results indicated that the only differences among stitched treatments were in rotational traction with the 2 cm by 2 cm treatment having the highest values, increasing the traction for athletic movements. Traffic had a significant effect on green cover, surface hardness, head injury criterion, ball rebound, force reduction, energy restitution, and vertical deformation, regardless of treatment. These findings suggest that the stitched fiber system did not significantly impact hybrid bermudagrass athletic field performance.

In the fall, bermudagrass athletic fields are overseeded with perennial ryegrass [ Lolium perenne L.] to provide a uniform playing surface to slowed or dormant bermudagrass. Chemical techniques have been utilized for quick and efficient spring transition of perennial ryegrass. Fraise mowing has been identified as a tool that can aid in ryegrass transition in the spring. These studies were to determine the effectiveness of spring transition comparing mechanical removal of perennial ryegrass overseeding to traditional techniques on ‘Riviera’ bermudagrass [C ynodon dactylon (L.) Pers.]. In 2017, field studies were conducted at the University of Tennessee Center for Athletic Field Safety (Knoxville, TN) and the Oklahoma State University Turfgrass Research Center (Stillwater, OK). The seven treatments for the study were: fraise mow at 6.4 mm from the grass surface, fraise mow at 12.7 mm from the grass surface, fraise mow at 19.1 mm from the grass surface, spray application of trifloxysulfuron at the 27.8 g ha −1 with non-ionic surfactant at 0.25% v/v, spray application of foramsulfuron at the 28.9 g ha −1 , scalping (19.1 mm) with a rotatory mower, and an untreated control. Treatments were initiated on 11 May 2017 in Stillwater, OK USA and 17 May 2017 in Knoxville, TN USA. Plots were monitored for six weeks following treatment application. Fraise mowing at 12.7 mm was identified as the optimum depth for perennial ryegrass transitioning in this study compared to chemical transitions. This study found that the fraise mowing at 12.7 mm removed more perennial ryegrass and maintained percent green turfgrass cover throughout the study. However, if time of use for the turfgrass area is not a primary concern then depths greater than 12.7 mm are effective at perennial ryegrass removal but delay spring green-up.

Athletic field managers often adjust agronomic practices according to the desires of coaches and athletes. One such agronomic practice often adjusted is mowing height. In an attempt to have athletes run faster, field managers are persuaded to reduce mowing height, thereby reducing potential friction from the surface on an athlete. With newer bermudagrass [ Cynodon datylon (L.) Pers.] and hybrid bermudagrass [ Cynodon dactylon (L.) Pers. × C. transvaalensis Burtt Davy] cultivars, maintaining a field at reduced mowing heights is much easier to achieve without apparent negative effects on surface performance. However, these expected effects have not been verified through rigorous research and are solely dependent on anecdotal data. The objectives of this study were to compare traffic tolerance of four hybrid bermudagrass cultivars - ‘Latitude 36 Turf Bermudagrass’ (Latitude 36) and ‘Northbridge Turf Bermudagrass’ (Northbridge), ‘Tifway’, and ‘Patriot’ - and two bermudagrass cultivars - ‘Riviera’, and ‘Hollywood’ - and determine the effect of mowing height on traffic tolerance. Treatments were arranged in a randomized complete block design with eight replications. Measurements of percent green cover, surface hardness, and peak rotational traction were collected before, during, and after simulated traffic. Latitude 36 and Northbridge were more traffic tolerant than any of the other cultivars tested. While there was not an interaction between cultivars and mowing height, the higher mowing height had greater traffic tolerance.

The use of synthetic turf (ST) has become a popular option for many athletic fields. Little is known about how surface hardness and infill depth spatial variability changes over time on third generation (3G) ST athletic fields. A research study was conducted to investigate the impact of field age on surface hardness and infill depth spatial variability from 12 3G ST athletic fields in Tennessee and Georgia (USA) between March 5, 2014 and April 8, 2014. The 3G ST athletic fields tested varied in fiber type including monofilament, slit film, and a combination of monofilament with slit film fibers. All 3G ST athletic fields were directly over gravel with no shockpad present. Surface hardness and infill depth were collected in the same location on all fields. Surface hardness was collected with the Toro Mobile Tester (400–450 samples/field) and infill depth was collected manually with a three-prong infill depth gauge (200–225 samples/field). As field age increased, surface hardness and spatial variability of the surface hardness increased significantly. Surface hardness and infill depth also had a significant negative relationship with one another. The increase in mean surface hardness and variability is partially attributed to infill depth loss and compaction of the remaining infill. Infill depth did not have a significant relationship with age, unless plots were outside the manufacturer’s recommendation for infill depth. Considering the nearly 3000 samples collected in this study, maintaining a minimum infill depth between 30 and 35 mm kept 90% of surface hardness data points below the National Football League limit of 100 Gmax. Results from this study highlight how 3G ST athletic fields can change with age, which may indicate the need for targeted infill applications and decompaction to improve field uniformity over time.

The objective of this study was to investigate the impact of brushing and infill maintenance of third generation (3G) synthetic turf on field safety. A split-plot randomized complete block design was used with six different fiber pile heights, infill depths, and shock pad combinations subjected to 120 games in the summer of 2017 at the Center for Athletic Field Safety (CAFS) in Knoxville, TN, USA. Traffic was applied with a CAFS traffic simulator. Half of the plots received maintenance every 20 games with a rotating power broom and infill applied to those below manufacturer’s recommendations. All 3G synthetic turf systems required maintenance to the same degree, and maintenance was necessary to keep surface hardness of 3G synthetic turf systems consistent and acceptable. Overall, field safety and consistency increased in this study due to maintenance, thus suggesting brushing and infill maintenance plays a vital role in maintaining high performance on 3G synthetic fields.

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.

The objective of this study is to determine the impact of three alternative infills of various particle size on athlete performance and safety in a third generation (3G) synthetic fields. A complete randomized design composed of three different infill materials (thermoplastic elastomer, coconut and cork mixture, and recycled Nike shoes (Nano)) with all infills having the same infill depth, fiber length, fiber density, and shock pad. The study took place at the Center for Athletic Field Safety (CAFS) during the summer of 2017 in Knoxville, TN. Each plot received 120 traffic events with the CAFS traffic simulator. This study found that alternative infills do impact the safety and performance of the field, while showing a variation of performance properties among the alternative infills. The results of this study indicate that particle size and distribution of the infill plays a key role in the superior field performance in 3G turf.

ABSTRACTShade from athletic stadium structures can be a significant detriment to turfgrass performance. The objective of this study was to determine the effects of shade on rooting and playing surface stability, measured as traction, on overseeded or non‐overseeded bermudagrass (Cynodon spp.) turf. An experiment was established in 2013 on a mature bermudagrass [Cynodon dactylon (L.) Pers. cv. Riviera] turf that was either overseeded with perennial ryegrass (Lolium perenne L.) or non‐overseeded. Shade structures were installed to create four light level treatments, including 0%, 30%, 60%, or 90% light‐reducing shade cloth. The light treatments resulted in average daily light integrals (DLI) of 40.8, 26.2, 14.8, and 3.3 mol m–2 d–1, respectively. Data were collected on rooting characteristics, species composition, and two forms of traction measurements. Moderate levels of shading (30%) caused a significant decline in rooting characteristics in non‐overseeded turf, while rooting of overseeded turf was not significantly affected until a 60% light reduction. Rotational resistance and peak horizontal force, measurements of athlete traction, were affected by increasing shade in both overseeded and non‐overseeded turf, but the association between traction and a minimum DLI was not conclusive. The persistence of bermudagrass in overseeded turf was significantly reduced at all shade levels studied. This study clearly demonstrates that rooting, bermudagrass persistence and traction of overseeded and non‐overseeded bermudagrass athletic fields are negatively affected by even modest levels of shade.

Core Ideas Limited impact of lower clip of the reel is noticed in bentgrass green quality and color. Double cutting and lower clip of the reel does not always lower green speeds. Lower clip of the reel picks up more sands than higher clip of the reel.

Studies are warranted to evaluate head injury criterion (HIC) on athletic fields to determine baseline numbers and compare those findings to current critical thresholds for impact attenuation. A two year (2016 and 2017) study was conducted on University of Tennessee athletic fields (Knoxville, TN, USA) to determine the effect of soil type (cohesive soil, United States Golf Association sand specifications) and grass species (Poa pratensis and Cynodon dactylon × C. transvaalensis) on HIC. Additionally soil moisture conditions monitored were: dry (0.06–0.16 m3/m3), acceptable (0.17–0.29 m3/m3), and wet (0.30–0.40 m3/m3). A linear relationship (r = 0.91) was identified between drop height (0.5–2.9 M) and HIC value (35-1423 HIC) on granular root zones of both grass types. However, HIC on cohesive soil is a function of soil water content in addition to drop height. These results demonstrate to aid in head injury prevention on cohesive soil athletic fields the HIC can be lowered by managing soil water content.

Creeping bentrgrass putting greens require intense management due to stoloniferous growth (thatch accumulation) and excessive wear and traffic by equipment and golfers. Increases in thatch and soil compaction are often managed with cultivation practices, which lead to downtime for golfers. Field research was conducted in Knoxville, TN, and Elizabethtown, KY, to compare new and traditional cultivation methods for their impact on playability on creeping bentgrass putting greens. Treatments included air injection, dry sand injection, solid tine cultivation topdressed with sand, hollow tine cultivation topdressed with sand, and non-treated control. Treatments were arranged in a randomized complete block design replicated three times at two locations. As determined 15 minutes after treatments, air injection resulted in the least reduction of green turfgrass cover, no ball roll reduction from the control, and lower reductions in surface firmness compared to other methods tested. Hollow tine had the greatest reduction in green turfgrass cover, lowest ball roll distance, and greatest reductions in surface firmness. Air injection had a lower impact on surface characteristics than hollow or solid cultivation. Because turf cover, ball roll, and firmness can all affect putting green playability, these findings indicate that air injection cultivation has the smallest impact on golfers immediately after a cultivation event.

Core Ideas Backtrack mowing produced the fastest green speeds compared with all other treatments. Shortening the clip of the reel or mowing in multiple directions removes more sand topdressing than standard mowing practices. Mowing patterns or clip of the reel had no visual effect on plant health.

Soil water content (SWC) influences the consistency and performance of athletic field surfaces. Two studies were conducted at the University of Tennessee Center for Athletic Field Safety, Knoxville, TN, to determine how SWC affects wear tolerance of hybrid bermudagrass [Cynodon dactylon (L.) Pers. × C. transvaalensis Burtt‐Davy, ‘Tifway’] on root zones composed of either silt loam (cohesive) or sand meeting US Golf Association specifications (noncohesive). Soil water content treatments for cohesive root zones averaged low (0.06–0.13 m3 m−3), medium (0.14–0.21 m3 m−3), medium‐high (0.22–0.29 m3 m−3), and high (0.30–0.37 m3 m−3); comparatively, SWC on noncohesive averaged low (0.05–0.11 m3 m−3), medium (0.12–0.19 m3 m−3), and high (0.20–0.27 m3 m−3). Differences in the amount of ranges between root zones were due to plant available water of the soil texture. Plots were subjected to 50 traffic events for 5 wk each fall over a 2‐yr period. Green turfgrass cover was reduced four times faster at high SWC than the low and medium SWC treatments on cohesive soil. All SWC treatments on noncohesive soil lost green turfgrass cover at a predictable rate. Surface hardness increased as SWC decreased for both root zones. Turfgrass shear strength decreased with traffic for all treatments on cohesive soils. Soil water content of noncohesive soils did not compound the effect of traffic on turfgrass shear strength. The optimal mean SWC ranges to maximize hybrid bermudagrass wear tolerance on cohesive soils were low to medium, and low to medium on noncohesive soils.

Crumb rubber (CR) generated from recycled tires has been used as a topdressing medium on cool‐season turfgrass athletic fields to increase tolerance to simulated traffic events (STE). Research was conducted at the University of Tennessee Center for Athletic Field Safety (Knoxville, TN) to determine optimal CR particle size and topdressing depth combinations for use on ‘Tifway’ hybrid bermudagrass [Cynodon dactylon (L.) Pers. × C. transvaalensis Burtt Davy]. Five CR topdressing materials varying in particle size and uniformity were evaluated; however, all were within 2.0 to 0.5 mm in diameter. Topdressing was applied to plots during 2011 and 2012. Each CR topdressing material was evaluated at three depths: 0.6, 1.3, or 1.9 cm. A non‐topdressed control was included for comparison. Twenty‐five STE were applied using a Cady Traffic Simulator. Traffic tolerance was quantified using digital image analysis to measure percentage green cover. Surface hardness differences were assessed using a Clegg Soil Impact Tester. Non‐topdressed control plots had percentage green cover reduced to <50% after only 12 STE compared with 18 to 20 STE for plots receiving CR at 0.6 to 1.9 cm (P < 0.001). No practical differences in percentage green cover were detected among CR particle sizes. Surface hardness decreased as topdressing depth increased, with minimal effects of CR particle size. Our findings indicate that CR topdressing can improve hybrid bermudagrass tolerance to STEs and that application depth was a more important factor in selecting CR topdressing than particle size.

Cynodon spp. (bermudagrass) golf courses and athletic fields in warm‐humid and warm‐arid regions are often annually overseeded with a cool‐season grass to improve turf performance during autumn and winter. Previous research has shown that preplant cultivation treatments to the C. dactylon base typically results in improved overseed establishment. Fraze mowing is a relatively new turf maintenance technique in which thatch and grass verdure is aggressively removed by blades attached to a revolving rotor. Because fraze mowers can significantly reduce C. dactylon competition for the overseed, a study was devised to determine the effectiveness of fraze mowing as a preplant technique prior to overseeding. The study was conducted in Lexington, KY, and Knoxville, TN, during the fall and winter of 2015–2016. Treatments were applied on 17 September and consisted of an untreated control, vertical mowing (one direction, 7.5 mm deep, 2.5‐cm spacing), and fraze mowing at 0.6‐, 1.2‐, and 2.5‐cm depths. Response variables included percentage cover, germination rating, surface hardness, and percentage cover the following spring and summer. Results showed no differences between preplant treatments for germination and percentage cover the following year. However, the fraze mowing treatments resulted in reduced percentage cover for 2 to 3 wk after treatment (WAT) compared with vertical mowing and the untreated control. By 3 WAT, the overseed had established and all plots had >90% cover. Surface hardness was only slightly affected by preplant treatment at just one location, and results were not consistent.

Applied Turfgrass ScienceVolume 11, Issue 1 ATS-2013-0047-BR p. 1-2 Brief Applications of Preemergence Herbicides in Spring Do Not Affect Bermudagrass Traffic Tolerance in Fall J. T. Brosnan, Corresponding Author J. T. Brosnan jbrosnan@utk.edu Dep. of Plant Sciences, Univ. of Tennessee, Knoxville, TN, 37996Corresponding author (jbrosnan@utk.edu).Search for more papers by this authorG. K. Breeden, G. K. Breeden Dep. of Plant Sciences, Univ. of Tennessee, Knoxville, TN, 37996Search for more papers by this authorK. H. Dickson, K. H. Dickson Dep. of Plant Sciences, Univ. of Tennessee, Knoxville, TN, 37996Search for more papers by this authorA. W. Thoms, A. W. Thoms Dep. of Plant Sciences, Univ. of Tennessee, Knoxville, TN, 37996Search for more papers by this authorJ.C. Sorochan, J.C. Sorochan Dep. of Plant Sciences, Univ. of Tennessee, Knoxville, TN, 37996Search for more papers by this author J. T. Brosnan, Corresponding Author J. T. Brosnan jbrosnan@utk.edu Dep. of Plant Sciences, Univ. of Tennessee, Knoxville, TN, 37996Corresponding author (jbrosnan@utk.edu).Search for more papers by this authorG. K. Breeden, G. K. Breeden Dep. of Plant Sciences, Univ. of Tennessee, Knoxville, TN, 37996Search for more papers by this authorK. H. Dickson, K. H. Dickson Dep. of Plant Sciences, Univ. of Tennessee, Knoxville, TN, 37996Search for more papers by this authorA. W. Thoms, A. W. Thoms Dep. of Plant Sciences, Univ. of Tennessee, Knoxville, TN, 37996Search for more papers by this authorJ.C. Sorochan, J.C. Sorochan Dep. of Plant Sciences, Univ. of Tennessee, Knoxville, TN, 37996Search for more papers by this author First published: 05 January 2014 https://doi.org/10.2134/ATS-2013-0047-BR All rights reserved. No part of this periodical may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. Permission for printing and for reprinting the material contained herein has been obtained by the publisher. Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume11, Issue12014Pages 1-2 RelatedInformation

ABSTRACTAthletic field playing quality encompasses both aesthetics as well as athlete‐to‐surface interactions that can affect injury incidence. Legislation restricting the use of herbicides on athletic fields may lead to increases in problematic weeds, such as large crabgrass (Digitaria sanguinalis L.) and white clover (Trifolium repens L.), which could reduce athletic field playing quality and potentially increase potential for athletic injuries. Research was conducted at the University of Tennessee Center for Athletic Field Safety (Knoxville, TN) during 2012 to 2013 to evaluate the playing quality of large crabgrass and white clover compared with weed‐free hybrid bermudagrass (C. dactylon ⋅ C. transvaalensis Burtt‐Davy, ‘Tifway’). All plots (3 by 3 m) were maintained as monostands and subjected to 18 simulated traffic events with a Cady traffic simulator each autumn over 2 yr. Large crabgrass and white clover lost green cover approximately 12 times faster than hybrid bermudagrass in this study. Consequently, surface hardness values on large crabgrass and white clover plots were ∼48 to 52% higher than those measured on hybrid bermudagrass after 18 simulated traffic events were applied. Changes in both surface hardness and rotational resistance were significantly correlated (P < 0.0001) to changes in green cover following simulated traffic. Our findings indicate that groundcover domination by weeds, such as large crabgrass and white clover, compromises the aesthetics and safety of natural grass athletic fields. Additional research is needed to evaluate athletic field playing quality on polystands of hybrid bermudagrass, large crabgrass, and white clover to determine acceptable thresholds of weed cover for player safety. Information of this nature would be useful for justifying various weed control measures such as herbicide applications.