title: Intensive training and reduced volume increases muscle FXYD1 expression and phosphorylation at rest and during exercise in athletes.
abstract: The present study examined the effect of intensive training in combination with marked reduction in training volume on phospholemman (FXYD1) expression and phosphorylation at rest and during exercise. Eight well-trained cyclists replaced their regular training with speed-endurance training (10-12 × ∼30-s sprints) two or three times per week and aerobic high-intensity training (4-5 × 3-4 min at 90-95% of peak aerobic power output) 1-2 times per week for 7 wk and reduced the training volume by 70%. Muscle biopsies were obtained before and during a repeated high-intensity exercise protocol, and protein expression and phosphorylation were determined by Western blot analysis. Expression of FXYD1 (30%), actin (40%), mammalian target of rapamycin (mTOR) (12%), phospholamban (PLN) (16%), and Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) γ/δ (25%) was higher (P < 0.05) than before the training intervention. In addition, after the intervention, nonspecific FXYD1 phosphorylation was higher (P < 0.05) at rest and during exercise, mainly achieved by an increased FXYD1 Ser-68 phosphorylation, compared with before the intervention. CaMKII, Thr-287, and eukaryotic elongation factor 2 Thr-56 phosphorylation at rest and during exercise, overall PKCα/β, Thr-638/641, and mTOR Ser-2448 phosphorylation during repeated intense exercise as well as resting PLN Thr-17 phosphorylation were also higher (P < 0.05) compared with before the intervention period. Thus, a period of high-intensity training with reduced training volume increases expression and phosphorylation levels of FXYD1, which may affect Na(+)/K(+) pump activity and muscle K(+) homeostasis during intense exercise. Furthermore, higher expression of CaMKII and PLN, as well as increased phosphorylation of CaMKII Thr-287 may have improved intracellular Ca(2+) handling.
authors.affiliation: Department of Nutrition, Exercise and Sports, Section of Integrated Physiology, University of Copenhagen, Copenhagen, Denmark; and.
authors.forename: Martin
authors.initials: M
authors.lastname: Thomassen
authors.affiliation: Department of Nutrition, Exercise and Sports, Section of Integrated Physiology, University of Copenhagen, Copenhagen, Denmark; and.
authors.forename: Thomas P
authors.initials: TP
authors.lastname: Gunnarsson
authors.affiliation: Department of Nutrition, Exercise and Sports, Section of Integrated Physiology, University of Copenhagen, Copenhagen, Denmark; and.
authors.forename: Peter M
authors.initials: PM
authors.lastname: Christensen
authors.affiliation: Cardiovascular Division, King's College London, The Rayne Institute, St. Thomas' Hospital, London, United Kingdom.
authors.forename: Davor
authors.initials: D
authors.lastname: Pavlovic
authors.affiliation: Cardiovascular Division, King's College London, The Rayne Institute, St. Thomas' Hospital, London, United Kingdom.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Shattock
authors.affiliation: Department of Nutrition, Exercise and Sports, Section of Integrated Physiology, University of Copenhagen, Copenhagen, Denmark; and jbangsbo@nexs.ku.dk.
authors.forename: Jens
authors.initials: J
authors.lastname: Bangsbo
mesh_terms: D000328:Adult; D001642:Bicycling / Q000502:physiology*; D020013:Calcium Signaling / Q000502:physiology; D015444:Exercise / Q000502:physiology*; D005786:Gene Expression Regulation / Q000502:physiology; D006801:Humans; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000502:physiology*; D010750:Phosphoproteins / Q000378:metabolism*; D010766:Phosphorylation; D064797:Physical Conditioning, Human / Q000502:physiology*; D005082:Physical Exertion / Q000502:physiology*; D012146:Rest / Q000502:physiology; D014018:Tissue Distribution
chemical_list: D008565:Membrane Proteins; D010750:Phosphoproteins; C069141:phospholemman
keywords: intense exercise training; phospholemman; protein signaling