Changes in metabolism but not myocellular signaling by training with CHO‐restriction in endurance athletes. Issue 17 (2nd September 2018)

• Record Type: Journal Article
• Authors: Gejl, Kasper D.; Vissing, Kristian; Hansen, Mette; Thams, Line; Rokkedal‐Lausch, Torben; Plomgaard, Peter; Meinild Lundby, Anne‐Kristine; Nybo, Lars; Jensen, Kurt; Holmberg, Hans‐Christer; Ørtenblad, Niels
• Is Part Of: Physiological reports. Volume 6:Issue 17(2018)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2018-09-02
• Subjects: Cycling -- endurance performance -- fat oxidation -- glycogen -- train‐low; Physiology -- Periodicals; 571
• DOI: 10.14814/phy2.13847
• Languages: English
• ISSNs: 2051-817X

Abstract

Abstract: Carbohydrate (CHO) restricted training has been shown to increase the acute training response, whereas less is known about the acute effects after repeated CHO restricted training. On two occasions, the acute responses to CHO restriction were examined in endurance athletes. Study 1 examined cellular signaling and metabolic responses after seven training‐days including CHO manipulation ( n = 16). The protocol consisted of 1 h high‐intensity cycling, followed by 7 h recovery, and 2 h of moderate‐intensity exercise (120SS). Athletes were randomly assigned to low (LCHO: 80 g) or high (HCHO: 415 g) CHO during recovery and the 120SS. Study 2 examined unaccustomed exposure to the same training protocol ( n = 12). In Study 1, muscle biopsies were obtained at rest and 1 h after 120SS, and blood samples drawn during the 120SS. In Study 2, substrate oxidation and plasma glucagon were determined. In Study 1, plasma insulin and proinsulin C‐peptide were higher during the 120SS in HCHO compared to LCHO (insulin: 0 min: +37%; 60 min: +135%; 120 min: +357%, P = 0.05; proinsulin C‐peptide: 0 min: +32%; 60 min: +52%; 120 min: +79%, P = 0.02), whereas plasma cholesterol was higher in LCHO (+15–17%, P = 0.03). Myocellular signaling did not differ between groups. p‐AMPK and p‐ACC were increased after 120SS (+35%, P = 0.03; +59%, P = 0.0004, respectively), with no alterations in p‐p38, p‐53, or p‐CREB. In Study 2, glucagon and fat oxidation were higher in LCHO compared to HCHO during the 120SS (+26–40%, P = 0.03; +44‐76%, P = 0.01 respectively). In conclusion, the clear respiratory and hematological effects of CHO restricted training were not translated into superior myocellular signaling after accustomization to CHO restriction. Abstract : This study investigated the acute metabolic and myocellular effects of training with CHO restriction after a 16‐day training period including seven training days with CHO restriction in highly trained endurance athletes. Despite marked metabolic alterations during exercise with after CHO restriction, myocellular signaling was similar to that observed after ingestion of an isocaloric CHO enriched diet.