dc.contributor.author | Christensen, PM | |
dc.contributor.author | Gunnarsson, TP | |
dc.contributor.author | Thomassen, M | |
dc.contributor.author | Wilkerson, DP | |
dc.contributor.author | Nielsen, JJ | |
dc.contributor.author | Bangsbo, J | |
dc.date.accessioned | 2016-03-02T10:15:40Z | |
dc.date.issued | 2015-07-07 | |
dc.description.abstract | The present study examined if high intensity training (HIT) could increase the expression of oxidative enzymes in fast-twitch muscle fibers causing a faster oxygen uptake (V˙O2) response during intense (INT), but not moderate (MOD), exercise and reduce the V˙O2 slow component and muscle metabolic perturbation during INT. Pulmonary V˙O2 kinetics was determined in eight trained male cyclists (V˙O2-max: 59 ± 4 (means ± SD) mL min(-1) kg(-1)) during MOD (205 ± 12 W ~65% V˙O2-max) and INT (286 ± 17 W ~85% V˙O2-max) exercise before and after a 7-week HIT period (30-sec sprints and 4-min intervals) with a 50% reduction in volume. Both before and after HIT the content in fast-twitch fibers of CS (P < 0.05) and COX-4 (P < 0.01) was lower, whereas PFK was higher (P < 0.001) than in slow-twitch fibers. Content of CS, COX-4, and PFK in homogenate and fast-twitch fibers was unchanged with HIT. Maximal activity (μmol g DW(-1) min(-1)) of CS (56 ± 8 post-HIT vs. 59 ± 10 pre-HIT), HAD (27 ± 6 vs. 29 ± 3) and PFK (340 ± 69 vs. 318 ± 105) and the capillary to fiber ratio (2.30 ± 0.16 vs. 2.38 ± 0.20) was unaltered following HIT. V˙O2 kinetics was unchanged with HIT and the speed of the primary response did not differ between MOD and INT. Muscle creatine phosphate was lower (42 ± 15 vs. 66 ± 17 mmol kg DW(-1)) and muscle lactate was higher (40 ± 18 vs. 14 ± 5 mmol kg DW(-1)) at 6 min of INT (P < 0.05) after compared to before HIT. A period of intensified training with a volume reduction did not increase the content of oxidative enzymes in fast-twitch fibers, and did not change V˙O2 kinetics. | en_GB |
dc.description.sponsorship | The study was supported by Team Danmark (Danish Elite Sport Organization). | en_GB |
dc.identifier.citation | Vol. 3, No. e12428 | en_GB |
dc.identifier.doi | 10.14814/phy2.12428 | |
dc.identifier.other | 3/7/e12428 | |
dc.identifier.uri | http://hdl.handle.net/10871/20371 | |
dc.language.iso | en | en_GB |
dc.publisher | Wiley Open Access | en_GB |
dc.relation.url | http://www.ncbi.nlm.nih.gov/pubmed/26152692 | en_GB |
dc.relation.url | http://physreports.physiology.org/content/3/7/e12428 | en_GB |
dc.rights | This is the final version of the article. Available from Wiley Open Access via the DOI in this record. | en_GB |
dc.subject | V˙O2 kinetics | en_GB |
dc.subject | high intensity training | en_GB |
dc.subject | interval training | en_GB |
dc.subject | type I fibers | en_GB |
dc.subject | type II fibers | en_GB |
dc.title | Unchanged content of oxidative enzymes in fast-twitch muscle fibers and V˙O2 kinetics after intensified training in trained cyclists. | en_GB |
dc.type | Article | en_GB |
dc.date.available | 2016-03-02T10:15:40Z | |
exeter.place-of-publication | United States | |
dc.description | Published | en_GB |
dc.description | Journal Article | en_GB |
dc.identifier.eissn | 2051-817X | |
dc.identifier.journal | Physiological Reports | en_GB |