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[{"key": "dc.contributor.advisor", "value": "Avela, Janne", "language": "", "element": "contributor", "qualifier": "advisor", "schema": "dc"}, {"key": "dc.contributor.author", "value": "Leukkunen, Juha", "language": "", "element": "contributor", "qualifier": "author", "schema": "dc"}, {"key": "dc.date.accessioned", "value": "2021-04-23T06:05:53Z", "language": null, "element": "date", "qualifier": "accessioned", "schema": "dc"}, {"key": "dc.date.available", "value": "2021-04-23T06:05:53Z", "language": null, "element": "date", "qualifier": "available", "schema": "dc"}, {"key": "dc.date.issued", "value": "2021", "language": "", "element": "date", "qualifier": "issued", "schema": "dc"}, {"key": "dc.identifier.uri", "value": "https://jyx.jyu.fi/handle/123456789/75169", "language": null, "element": "identifier", "qualifier": "uri", "schema": "dc"}, {"key": "dc.description.abstract", "value": "Fyysisess\u00e4 v\u00e4symyksess\u00e4 lihasten voimantuottokyky heikkenee. Esimotorinen aivojen aktivaatio on yhdistetty tiedostamattomiin liikkeen valmisteluun ja aloitukseen liittyviin toimintoihin. Valmiuspotentiaali on liikett\u00e4 1.5 sekuntia edelt\u00e4v\u00e4 negatiivinen j\u00e4nnitesiirtym\u00e4, jonka voimakkuus kuvaa kortikaalisen aktivaation suuruutta. Viimeaikaiset tutkimukset ovat osoittaneet ristiriitaisia tuloksia liittyen valmiuspotentiaalin muunteluun v\u00e4symyksess\u00e4. Osassa tutkimuksia valmiuspotentiaalin on osoitettu lis\u00e4\u00e4ntyv\u00e4n ja osassa v\u00e4hentyv\u00e4n. Valmiuspotentiaalin on ehdotettu koostuvan sek\u00e4 positiivisista ett\u00e4 negatiivisista siirtymist\u00e4, ja ett\u00e4 sen dynamiikka noudattaisi stokastista aaltoilevaa aktiivisuutta p\u00e4\u00e4t\u00f6ksentekokynnyksen alapuolella. Positiivisten ja negatiivisten valmiuspotentiaalien voimakkuuden muuntelua ja niiden yhteytt\u00e4 kortikospinaaliseen herkkyyteen ei ole aiemmin tutkittu v\u00e4symyksess\u00e4.\n\n10 koehenkil\u00f6\u00e4 osallistui ristikk\u00e4isasetelma-tutkimukseen, joka koostui kontrolli- ja v\u00e4sytyskuormituksista. Molemmissa kuormituksissa suoritettiin 60 isometrista plantaarifleksiota jaettuna 30 suorituksen blokkeihin 1 ja 2. Valmiuspotentiaali mitattiin itsealoitetuista lihassupistuksista, joita toistettiin noin 20 sekunnin v\u00e4lein. V\u00e4sytyssupistuksissa (30 + 30) voimaa tuotettiin ensimm\u00e4inen nelj\u00e4 sekuntia 50 % maksimaalisesta isometrisesta lihassupistuksen (MVC) v\u00e4\u00e4nt\u00f6momentista, josta siirryttiin suoraan kolmen sekunnin maksimaaliseen supistukseen. Kontrollisupistuksissa (30 + 30) voimaa tuotettiin seitsem\u00e4n sekuntia 10 % MVC v\u00e4\u00e4nt\u00f6momentista. Blokkien 1 ja 2 v\u00e4liss\u00e4 pidettiin viiden minuutin tauko. Ennen blokkia 1 (PRE), blokkien 1 ja 2 v\u00e4liss\u00e4 (POST1) ja blokin 2 j\u00e4lkeen (POST2) mitattiin: 1) tahdonalaista aktivaatiota kortikaalisella transkraniaalisella magneettistimulaatiolla (TMS) sek\u00e4 \u00e4\u00e4reishermon tasavirtastimulaatiolla, 2) kortikaalisen stimuluksen j\u00e4lkeist\u00e4 vaimentuneen lihasaktiivisuuden kestoa ja 3) kuormittuneisuuden tunnetta. Kortikospinaalista herkkyytt\u00e4 mitattiin TMS:ll\u00e4 indusoitujen motoristen her\u00e4tevasteiden rekrytointik\u00e4yr\u00e4n\u00e4 ainoastaan PRE ja POST2.\n\nV\u00e4sytyksen aikana MVC v\u00e4\u00e4nt\u00f6momentti laski v\u00e4leill\u00e4 PRE 291 \u00b1 41 Nm ja POST1 211 \u00b1 37 Nm (p \u22640.01) sek\u00e4 PRE ja POST2 200 \u00b1 36 Nm (p\u22640.01). Positiivisia valmiuspotentiaaleja (positiivisten ja negatiivisen valmiuspotentiaalien erotus) oli enemm\u00e4n v\u00e4sytyksess\u00e4 (Block1 5.0 \u00b1 12.9 ja Block2 2.0 \u00b1 6.2) ja negatiivisia enemm\u00e4n kontrollissa (Block1 -5.5 \u00b1 6.2, p\u22640.05 ja Block2 -6.0 \u00b1 3.8, p\u22640.01). Valmiuspotentiaalin voimakkuus lis\u00e4\u00e4ntyi 1.5 sekuntia ennen soleus-lihaksen lihasaktiivisuuden alkua. V\u00e4sytyksess\u00e4 negatiivinen valmiuspotentiaali muuttui negatiivisemmaksi ja positiivinen positiivisemmaksi siirrytt\u00e4ess\u00e4 kohti lihasaktiivisuuden alkua. V\u00e4sytyksess\u00e4 positiivisen valmiuspotentiaalin my\u00f6h\u00e4isen komponentin RP2 pieneneminen blokkien 1 ja 2 v\u00e4lill\u00e4 korreloi negatiivisesti (r=-0.97, p=0.0063, n=5) v\u00e4\u00e4nt\u00f6momentin v\u00e4henemisen kanssa v\u00e4lill\u00e4 PRE ja POST2.\n\nTahdonalaisen aktivaation taso kortikaalisella stimulaatiolla laski v\u00e4sytyksen aikana v\u00e4lill\u00e4 PRE 91 \u00b1 5 % ja POST2 80 \u00b1 14 % (p\u22640.05), ja \u00e4\u00e4reishermon stimulaatiolla v\u00e4leill\u00e4 PRE 99 \u00b1 2 % ja POST1 89 \u00b1 5 % (p\u22640.01) sek\u00e4 PRE ja POST2 93 \u00b1 5 % (p\u22640.01). Vaimentunut lihasaktiivisuuden jakso kortikaalisen stimuluksen j\u00e4lkeen lyheni v\u00e4sytyksen aikana v\u00e4leill\u00e4 PRE 0.144 \u00b1 0.011 s ja POST1 0.132 \u00b1 0.012 s (p\u22640.05) sek\u00e4 PRE ja POST2 0.134 \u00b1 0.011 s (p\u22640.05). Kuormittuneisuuden tunne lis\u00e4\u00e4ntyi v\u00e4sytyksen aikana v\u00e4leill\u00e4 PRE 1.2 \u00b1 2.3 ja POST1 6.7 \u00b1 2.2 (p\u22640.01) sek\u00e4 PRE ja POST2 8.4 \u00b1 2.0 (p\u22640.001). Rekrytointik\u00e4yr\u00e4n voimakkuus v\u00e4\u00e4nt\u00f6momentin tasolla 20%MVC v\u00e4\u00e4nt\u00f6momentista lis\u00e4\u00e4ntyi yhtenev\u00e4sti kontrollin ja v\u00e4sytyksen aikana, mutta ei merkitsev\u00e4sti.\n\nTutkimuksen mukaan v\u00e4symyst\u00e4 aiheuttava intervallityyppinen maksimaalinen isometrinen plantaarifleksio- kuormitus muuntelee positiivisten ja negatiivisten valmiuspotentiaalien osuuksia yhdess\u00e4 maksimaalisen v\u00e4\u00e4nt\u00f6momentin laskun kanssa, mik\u00e4 indikoi ei-optimaalista v\u00e4hentyneen herkkyyden tilaa motorisen aivokuoren hermosoluverkoissa liikkeen aloituksen aikana suurimmassa osassa lihassupistuksia.", "language": "fi", "element": "description", "qualifier": "abstract", "schema": "dc"}, {"key": "dc.description.abstract", "value": "Ability to generate force decreases during performance fatigue. Premotor activity has been connected to unconscious processes related to movement preparation and ignition. Readiness potential (RP) is a cortical voltage drift preceding movement onset by 1.5-s and its negative amplitude is a marker of neural activity. Recent studies have shown conflicting results about RP amplitude both increasing and decreasing during fatigue. It has been suggested that RP consists of both positive and negative shifts, is based on a stochastic fluctuating activity under decision threshold, and is probabilistic in nature. Slope-dependent RP amplitude modulation during fatigue and how it is linked to corticospinal excitability (CSE) has not been previously studied.\n\n10 volunteers participated in a crossover study fatiguing and control protocol of 60 isometric plantar flexions divided into blocks 1 and 2 of 30 contractions each. Contractions were self-started every ~20- s and RP was measured. Fatiguing contractions (30 + 30) started with 4-s at 50%MVC and ended in 3- s maximal contraction, while control contraction lasted 7-s at 10%MVC. There was a 5-min break be- tween blocks. Cortical and peripheral voluntary activation level (CVAL and PVAL, respectively), cortical silent period (SP), and rating of perceived exertion (RPE) was measured before Block1 (PRE) and between and after Block1 (POST1) and 2 (POST2). Recruitment curve was measured with transcranial magnetic stimulation (TMS) only at PRE and POST2.\n\nThe fatiguing protocol resulted in a significant decrease in MVC torque from PRE (291\u00b141Nm), to POST1 (211\u00b137Nm) and POST2 (200\u00b136Nm). There was a significantly larger occurrence of RPs with positive slope (measured as a difference in number of positively and negatively categorized RPs) during fatiguing contractions (Block1 5.0\u00b112.9 and Block2 2.0\u00b16.2) and significantly larger amount of negative RPs during control contractions (Block1 -5.5\u00b16.2 and Block2 -6.0\u00b13.8). RP amplitude showed a significant effect of time starting 1.5-s before electromyographic (EMG) activity of the soleus muscle (SOL). Negative RPs amplitude got more negative during control and positive RPs got more positive during fatigue closer to EMG onset. During fatigue a significant negative correlation (r=-0.97, p=0.0063, n=5) was found between decrease in positive RP2 amplitude from Block1 to Block2 and decrease in torque from PRE to POST2.\n\nDuring fatigue CVAL (PRE 91\u00b15% to POST2 80\u00b114%), PVAL (PRE 99\u00b12% to POST1 89\u00b15% and PRE to POST2 93\u00b15%), cortical SP (PRE 0.144\u00b10.011-s to POST1 0.132\u00b10.012-s and PRE to POST2 0.134\u00b10.011-s) were significantly reduced while RPE was significantly increased (PRE 1.2\u00b12.3 to POST1 6.7\u00b12.2 and PRE to POST2 8.4\u00b12.0). Recruitment curve during 20%MVC showed a non-significant increasing trend in both conditions.\n\nIn conclusion, fatiguing intermittent maximal isometric plantar flexion exercise modulated the distribution of slope-dependent RPs concomitant with a decrease in MVC torque, which indicates suboptimal decreased excitatory state of M1 cortex neural circuits during movement ignition in the higher proportion of the contractions.", "language": "en", "element": "description", "qualifier": "abstract", "schema": "dc"}, {"key": "dc.description.provenance", "value": "Submitted by Paivi Vuorio (paelvuor@jyu.fi) on 2021-04-23T06:05:53Z\nNo. of bitstreams: 0", "language": "en", "element": "description", "qualifier": "provenance", "schema": "dc"}, {"key": "dc.description.provenance", "value": "Made available in DSpace on 2021-04-23T06:05:53Z (GMT). No. of bitstreams: 0\n Previous issue date: 2021", "language": "en", "element": "description", "qualifier": "provenance", "schema": "dc"}, {"key": "dc.format.extent", "value": "81", "language": "", "element": "format", "qualifier": "extent", "schema": "dc"}, {"key": "dc.format.mimetype", "value": "application/pdf", "language": null, "element": "format", "qualifier": "mimetype", "schema": "dc"}, {"key": "dc.language.iso", "value": "eng", "language": null, "element": "language", "qualifier": "iso", "schema": "dc"}, {"key": "dc.rights", "value": "In Copyright", "language": "en", "element": "rights", "qualifier": null, "schema": "dc"}, {"key": "dc.subject.other", "value": "Bereitschaftspotential", "language": "", "element": "subject", "qualifier": "other", "schema": "dc"}, {"key": "dc.subject.other", "value": "cortical silent period", "language": "", "element": "subject", "qualifier": "other", "schema": "dc"}, {"key": "dc.subject.other", "value": "corticospinal excitability", "language": 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