*Article* **The Impact of Grounding in Running Shoes on Indices of Performance in Elite Competitive Athletes**

**Borja Muniz-Pardos 1,2,3, Irina Zelenkova 2,3, Alex Gonzalez-Aguero 1,2,3, Melanie Knopp 4, Toni Boitz 4, Martin Graham 4, Daniel Ruiz 4, Jose A. Casajus 2,3,5 and Yannis P. Pitsiladis 3,6,7,8,\***


#### **Citation:** Muniz-Pardos, B.;

Zelenkova, I.; Gonzalez-Aguero, A.; Knopp, M.; Boitz, T.; Graham, M.; Ruiz, D.; Casajus, J.A.; Pitsiladis, Y.P. The Impact of Grounding in Running Shoes on Indices of Performance in Elite Competitive Athletes. *Int. J. Environ. Res. Public Health* **2022**, *19*, 1317. https://doi.org/10.3390/ ijerph19031317

Academic Editors: Roberto Alonso González Lezcano, Francesco Nocera and Rosa Giuseppina Caponetto

Received: 24 November 2021 Accepted: 23 January 2022 Published: 25 January 2022

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**Abstract:** The introduction of carbon fiber plate shoes has triggered a plethora of world records in running, which has encouraged shoe industries to produce novel shoe designs to enhance running performance, including shoes containing conductor elements or "grounding shoes" (GS), which could potentially reduce the energy cost of running. The aim of this study was to examine the physiological and perceptual responses of athletes subjected to grounding shoes during running. Ten elite runners were recruited. Firstly, the athletes performed an incremental running test for VO2max and anaerobic threshold (AT) determination, and were familiarized with the two shoe conditions (traditional training shoe (TTS) and GS, the latter containing a conductor element under the insole). One week apart, athletes performed running economy tests (20 min run at 80% of the AT) on a 400 m dirt track, with shoe conditions randomized. VO2, heart rate, lactate, and perceived fatigue were registered throughout the experiment. No differences in any of the physiological or perceptual variables were identified between shoe conditions, with an equal running economy in both TTS and GS (51.1 <sup>±</sup> 4.2 vs. 50.9 <sup>±</sup> 5.1 mL kg−<sup>1</sup> min<sup>−</sup>1, respectively). Our results suggest that a grounding stimulus does not improve the energy cost of running, or the physiological/perceptual responses of elite athletes.

**Keywords:** earthing; environmental physiology; running performance; running economy; shoe technology; grounding
