Prior Sars-Cov-2 Infection Does Not Reduce Immunocompetence In Humans Challenged With Exertional Heat Stress

Karissa Fryar, Nathan Conrad, Ben Lee, Trevor Gillum, Matthew Kuennen

Research output: Contribution to journalMeeting Abstractpeer-review


PURPOSE: Animal models suggest that some forms of viral infection can increase risk for exertional heatstroke (EHS) via reduced immunocompetence. Immunocompetence was examined in persons with prior clinical diagnosis of SARS-CoV-2 infection, who were challenged with 60 min of cycling exercise in hot, dry ambient conditions.

METHODS: Eighteen participants (Age: 21 ± 1 years, Stature: 1.7 ± 0.1 m, Mass: 70.3 ± 2.7 kg, VO2max: 47 ± 2 mL-1 kg-1.min-1) completed 1 hr of cycling exercise in an environmental chamber (35 °C/35% RH) at an intensity that elicited 9.0 W/kg of metabolic heat production. Ten participants had been previously diagnosed with SARS-CoV-2. Eight participants served as Control. Blood samples collected before (Pre), after (Post), 1 h after (1-Post), and 3 h after (3-Post) exercise, were assayed for soluble cluster of differentiation 14 (sCD-14), soluble intercellular adhesion molecule 1 (sICAM-1), interferon gamma (IFN-y), and interleukin 8 (IL-8). Heart rate (HR), esophageal and mean body temperatures (Tc & Tb), minute ventilation (VE), and oxygen consumption (VO2) were measured throughout exercise. Between-group differences were examined using RM-ANOVA with Bonferroni Post Hocs.

RESULTS: Persons with prior SARS-Cov-2 infection exhibited elevated plasma concentrations of sCD-14 at Pre, Post, 1-Post, and 3-Post (Range: 8.2-17.1%; all p < 0.05) and elevated IFN-y concentrations at 1-Post exercise (59.6 ± 11 pg/ml; p < 0.05). Plasma IL-8 and sICAM-1 concentrations were not different between groups [both p > 0.05]. When compared to Control, persons with prior SARS-CoV-2 infection did not exhibit greater elevations in HR (87 ± 5% vs 82 ± 8% of HRmax), Tc (1.3 ± 0.5 vs 1.3 ± 0.6 °C), Tb (1.2 ± 0.4 vs 1.1 ± 0.5 °C), VE (40.7 ± 7.0 vs 36.8 ± 7.8 L/min) or VO2 (22.9 ± 2.7 vs 24.3 ± 2.4 mL-1 kg-1.min-1) during the 1 hr cycling challenge [all p > 0.05].

CONCLUSIONS: IFN-y is secreted by activated t-lymphocytes and exhibits direct anti-viral activity. sCD-14 mediates lipopolysaccharide (LPS) clearance via transport of cell-bound LPS to plasma lipoproteins. Collectively, elevated IFN-y and sCD-14 in persons with prior SARS-CoV-2 infection indicates immunocompetence was maintained in the hours following exertional heat stress. These data may have additional context in the area(s) of latent infection and viral reactivation
Original languageEnglish
Pages (from-to)118-119
Number of pages2
JournalMedicine and Science in Sports and Exercise
Issue number9S
Publication statusPublished - Sept 2023


  • Physical Therapy, Sports Therapy and Rehabilitation
  • Orthopedics and Sports Medicine


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