{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,10]],"date-time":"2026-02-10T19:54:15Z","timestamp":1770753255582,"version":"3.50.0"},"reference-count":27,"publisher":"Public Library of Science (PLoS)","issue":"2","license":[{"start":{"date-parts":[[2026,2,9]],"date-time":"2026-02-09T00:00:00Z","timestamp":1770595200000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["www.plosone.org"],"crossmark-restriction":false},"short-container-title":["PLoS One"],"abstract":"\n Background<\/jats:title>\n The effect of familiarization with the critical speed (CS) testing process on the outcome of CS tests has yet to be determined.<\/jats:p>\n <\/jats:sec>\n \n Objectives<\/jats:title>\n The main aims of the present study were to determine whether a familiarization session prior to CS testing sessions affects time to task-failure (TTF) on subsequent tests and CS estimations, and whether individual characteristics such as sex and fitness status influence any familiarization effect.<\/jats:p>\n <\/jats:sec>\n \n Methods<\/jats:title>\n \n 27 healthy adults (10 females, 25\u2009\u00b1\u20094 yrs) performed the following treadmill protocol:\n i)<\/jats:italic>\n a maximal incremental test to identify peak speed;\n ii)<\/jats:italic>\n a familiarization constant-intensity trial (CT\n fam<\/jats:sub>\n ) at the intensity of the first constant-intensity trial used for CS determination (CT\n CS<\/jats:sub>\n ), and\n iii)<\/jats:italic>\n four randomly ordered maximal constant-intensity trials at ~ 85%, 92%, 98%, and 105% of peak speed. CS was estimated using 2-parameter hyperbolic, linear, and 1\/time models including the CT\n fam<\/jats:sub>\n (CS not familiarized) or the CT\n CS<\/jats:sub>\n (CS familiarized). Familiarized and not-familiarized TTFs and CSs were compared using Wilcoxon tests. Sex effect was analyzed using Mann-Whitney test on the difference in the TTF between CT\n CS<\/jats:sub>\n and CT\n fam<\/jats:sub>\n . The correlation between peak speed and difference in the TTF between CT\n CS<\/jats:sub>\n and CT\n fam<\/jats:sub>\n was assessed using Spearman\u2019s rank correlation. \u03b1 was set at 0.05.\n <\/jats:p>\n <\/jats:sec>\n \n Results<\/jats:title>\n \n CT\n fam<\/jats:sub>\n TTF (399 [299] s, median [interquartile range]) was lower (p\u2009=\u20090.009) than CT\n CS<\/jats:sub>\n TTF (495[316] s), whereas CS familiarized and not-familiarized were not different in any model (p\u2009>\u20090.05). Sex did not affect the differences between familiarized and not-familiarized TTFs and CS. However, differences in the TTF between CT\n CS<\/jats:sub>\n and CT\n fam<\/jats:sub>\n were negatively correlated with peak speed (\u03c1 = \u22120.381, p\u2009=\u20090.050).\n <\/jats:p>\n <\/jats:sec>\n \n Conclusions<\/jats:title>\n \n Familiarization with constant-intensity trials affected the TTF but not CS. Importantly, the familiarization effect was larger in less fit individuals, showing a negative correlation between the TTF differences (i.e., CT\n CS<\/jats:sub>\n minus CT\n fam<\/jats:sub>\n ) and peak speed.\n <\/jats:p>\n <\/jats:sec>","DOI":"10.1371\/journal.pone.0341141","type":"journal-article","created":{"date-parts":[[2026,2,9]],"date-time":"2026-02-09T18:28:05Z","timestamp":1770661685000},"page":"e0341141","update-policy":"https:\/\/doi.org\/10.1371\/journal.pone.corrections_policy","source":"Crossref","is-referenced-by-count":0,"title":["The effect of a familiarization critical speed testing session on critical speed determination during treadmill 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