Quantifying Field Variability Effects on Surface Performance and Athletes

Abstract

Athletic field variability refers to differences in surface conditions within or between athletic fields, often influenced by several factors. In the U.S. transition zone, turfgrass stressors like spring dead spot (SDS; Ophiosphaerella spp.) and winter injury are common on bermudagrass (Cynodon dactylon) athletic fields, yet limited research has evaluated how variability from these stressors affects field performance or safety. Existing literature often oversimplifies playing surfaces into "natural turfgrass" or "synthetic turf," overlooking meaningful within- and between-field variability. To address these gaps, a two-part study was conducted on hybrid bermudagrass [Cynodon dactylon (L.) Pers. × Cynodon transvaalensis Burtt-Davy] athletic fields to: 1) evaluate how SDS and winter injury influence playing surface characteristics such as hardness, soil moisture, and rotational resistance, and 2) assess how these stressors alter athlete-surface and ball-surface interactions. Separately, a third study used wearable technologies to quantify how surface variability within and between natural and synthetic turf fields influences athlete safety and performance. The first study showed SDS and winter injury significantly reduced rotational resistance compared to asymptomatic turfgrass, decreasing traction and potentially increasing the risk of slipping. Winter injury areas also had higher hardness, surpassing recommended thresholds and elevating impact injury risk. Part two of the first study used a mechanical device that simulated athlete-surface interactions, recording metrics such as vertical force, surface recoil, stability, and traction, along with a device measuring ball rebound. SDS-affected areas produced greater vertical force, recoil, and displacement, while both SDS and winter injury increased ball bounce height, indicating reduced energy absorption and compromised playability. Results from the third study showed variability within and between both surface types, further suggesting broad claims regarding field performance of natural vs. synthetic fields should not be made because of field variability inconsistencies. Synthetic fields tested were generally harder, especially under higher traffic. Wearable data showed a positive correlation between hardness and lower limb impact intensity, and survey data suggested that athletes preferred a well-maintained natural grass field but favored synthetic over poorly maintained natural fields. Collectively, these studies underscore the effects of surface variability on field performance, athlete biomechanics, and perceptions of field quality. Monitoring surface properties to maximize turfgrass health are encouraged to optimize field consistency and athlete safety.