{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,16]],"date-time":"2026-09-16T06:04:52Z","timestamp":1789538692385,"version":"build-2803163510"},"reference-count":58,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2026,9,16]],"date-time":"2026-09-16T00:00:00Z","timestamp":1789516800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Nutr."],"abstract":"<jats:sec>\n                    <jats:title>Purpose<\/jats:title>\n                    <jats:p>This study aimed to investigate the effects of caffeinated chewing gum on performance during a prolonged intermittent-sprint test (IST) under normobaric hypoxia.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>Ten team-sport athletes (six men and four women) participated in a double-blind, randomized crossover trial with a counterbalanced treatment order, chewing either caffeinated gum (6 mg\/kg) or placebo gum on two separate occasions, 7 days washout period. After chewing for 10 min, participants performed an IST protocol in hypoxia (inspired oxygen fraction: 16.5 \u00b1 0.2%, ~2,000 m). The IST consisted of two 40-min halves separated by a 15-min halftime recovery, each comprising twenty 2-min blocks with an 8-s all-out sprint, 100 s of active recovery at 35% of peak oxygen uptake, and 12 s of passive rest. Total work done, power output, muscle and cerebral oxygenation were recorded.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>\n                      Total work done was significantly greater with caffeinated gum, increasing by 4.4% in the first half [mean difference = 6 kJ, 95% CI (2.71, 10.08)] and a 2.9% increase in the second half [mean difference = 4 kJ, 95% CI (1.18, 6.57)] compared to placebo (all\n                      <jats:italic>p<\/jats:italic>\n                      &amp;lt; 0.05). Caffeinated gum also significantly increased both peak and mean power output (all\n                      <jats:italic>p<\/jats:italic>\n                      &amp;lt; 0.05). Cerebral total hemoglobin and oxyhemoglobin were higher in both halves with caffeinated gum, while muscle deoxyhemoglobin and reoxygenation capacity were significantly higher in the first half compared to placebo (all\n                      <jats:italic>p<\/jats:italic>\n                      &amp;lt; 0.05).\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusion<\/jats:title>\n                    <jats:p>Caffeinated chewing gum (6 mg\/kg) enhances prolonged repeated-sprint performance under normobaric hypoxia, accompanied by increased cerebral oxygenation and muscle reoxygenation capacity.<\/jats:p>\n                  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