{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,21]],"date-time":"2026-04-21T06:46:35Z","timestamp":1776753995543,"version":"3.51.2"},"reference-count":58,"publisher":"Public Library of Science (PLoS)","issue":"2","license":[{"start":{"date-parts":[[2023,2,16]],"date-time":"2023-02-16T00:00:00Z","timestamp":1676505600000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Project I&D&I HEALTH-UNORTE","award":["NORTE-01-0145-FEDER-000039, co-funded by Regional Development European Fund (FEDER) through NORTE 2020 (North Region Operacional Program 2014\/2020)"],"award-info":[{"award-number":["NORTE-01-0145-FEDER-000039, co-funded by Regional Development European Fund (FEDER) through NORTE 2020 (North Region Operacional Program 2014\/2020)"]}]}],"content-domain":{"domain":["www.plosone.org"],"crossmark-restriction":false},"short-container-title":["PLoS ONE"],"abstract":"<jats:p>The aim of this pilot study was to assess the effect of muscle contraction type on SmO<jats:sub>2<\/jats:sub> during a dynamic contraction protocol (DYN) and a holding isometric contraction protocol (ISO) in the back squat exercise. Ten voluntary participants (age: 26.6 \u00b1 5.0 years, height: 176.8 \u00b1 8.0 cm, body mass: 76.7 \u00b1 8.1 kg, and one-repetition maximum (1RM): 112.0 \u00b1 33.1 kg) with back squat experience were recruited. The DYN consisted of 3 sets of 16 repetitions at 50% of 1RM (56.0 \u00b1 17.4 kg), with a 120-second rest interval between sets and 2 seconds per movement cycle. The ISO consisted of 3 sets of 1 isometric contraction with the same weight and duration as the DYN (32 seconds). Through near-infrared spectroscopy (NIRS) in the <jats:italic>vastus lateralis<\/jats:italic> (VL), <jats:italic>soleus<\/jats:italic> (SL), <jats:italic>longissimus<\/jats:italic> (LG), and <jats:italic>semitendinosus<\/jats:italic> (ST) muscles, the minimum SmO<jats:sub>2<\/jats:sub> (SmO<jats:sub>2 min<\/jats:sub>), mean SmO<jats:sub>2<\/jats:sub> (SmO<jats:sub>2 avg<\/jats:sub>), percent change from baseline (SmO<jats:sub>2 \u0394deoxy<\/jats:sub>) and time to recovery 50% of baseline value (<jats:italic>t<\/jats:italic> SmO<jats:sub>2 50%reoxy<\/jats:sub>) were determined. No changes in SmO<jats:sub>2 avg<\/jats:sub> were found in the VL, LG, and ST muscles, however the SL muscle had lower values in DYN, in the 1<jats:sup>st<\/jats:sup> set (<jats:italic>p<\/jats:italic> = 0.002) and in the 2<jats:sup>nd<\/jats:sup> set (<jats:italic>p<\/jats:italic> = 0.044). In terms of SmO<jats:sub>2 min<\/jats:sub> and \u0394SmO<jats:sub>2 deoxy<\/jats:sub>, only the SL muscle showed differences (<jats:italic>p<\/jats:italic>\u22640.05) and lower values in the DYN compared to ISO regardless of the set. The <jats:italic>t<\/jats:italic> SmO<jats:sub>2 50%reoxy<\/jats:sub> was higher in the VL muscle after ISO, only in the 3<jats:sup>rd<\/jats:sup> set. These preliminary data suggested that varying the type of muscle contraction in back squat with the same load and exercise time resulted in a lower SmO<jats:sub>2 min<\/jats:sub> in the SL muscle in DYN, most likely because of a higher demand for specialized muscle activation, indicating a larger oxygen supply-consumption gap.<\/jats:p>","DOI":"10.1371\/journal.pone.0281885","type":"journal-article","created":{"date-parts":[[2023,2,16]],"date-time":"2023-02-16T18:40:05Z","timestamp":1676572805000},"page":"e0281885","update-policy":"https:\/\/doi.org\/10.1371\/journal.pone.corrections_policy","source":"Crossref","is-referenced-by-count":11,"title":["Comparing the effects of dynamic and holding isometric contractions on cardiovascular, perceptual, and near-infrared spectroscopy parameters: A pilot 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