Muscle thickness and inflammation during a 50km ultramarathon in recreational runners

• Published in: PloS one 2022-09, Vol.17 (9), p.e0273510-e0273510
• Main Authors: Landers-Ramos, Rian Q, Dondero, Kathleen, Nelson, Christa, Ranadive, Sushant M, Prior, Steven J, Addison, Odessa
• Format: Article
• Language: English
• Subjects: Aerobics; Athletes; Biology and Life Sciences; Creatine; Creatine kinase; Cytokines; Exercise; Fitness equipment; Inflammation; Inflammatory response; Interleukin 6; Kinases; Knee; Marathons; Measurement; Medicine and Health Sciences; Morphology; Muscle contraction; Muscle strength; Muscles; Musculoskeletal system; Participation; Physical fitness; Physical Sciences; Physiological aspects; Research and Analysis Methods; Runners (Sports); Running; Skeletal muscle; Thickness; Torque; Tumor necrosis factor-TNF; Tumor necrosis factor-α; Ultramarathon; Ultrasonic imaging
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0273510

This study examined changes in circulating levels of inflammatory cytokines [IL-6, sIL-6R, TNF-[alpha], and calprotectin], skeletal muscle morphology, and muscle strength following a 50km race in non-elite athletes. Eleven individuals (8 men; 3 women) underwent pre-race assessments of rectus femoris muscle thickness (resting and contracted) using ultrasound, isometric knee extensor torque, and plasma cytokines. Measures were repeated after 10km of running, the 50km finish (post-race), and again 24-hrs post-race. Compared with baseline values, [DELTA] muscle thickness (resting to contracted) increased significantly 24 hrs post-race (11 ± 11% vs. 22 ± 8%; P = 0.01). Knee extensor torque was significantly reduced immediately post-race (151 ± 46 vs. 134 ± 43 Nm; P = 0.047) but remained similar to post-race values at 24 hrs post-race (P = 0.613). Compared with pre-race levels, IL-6 and calprotectin concentrations increased 302% and 50% after 10km, respectively (P0.05 for both). Creatine kinase levels rose steadily during and after the race, peaking 24-hrs post-race (184 ± 113 U/L pre-race vs. 1508 ± 1815 U/L 24-hrs post-race; P = 0.005). This is the first report of delayed increases in [DELTA] muscle thickness at 24 hrs post-50km, which are preceded by reductions in knee extensor torque and elevations in plasma IL-6, and calprotectin. Recreational athletes should consider the acute muscle inflammatory response when determining training and recovery strategies for 50km participation.