title: Fuel selection during short-term submaximal treadmill exercise in the cold is not affected by pre-exercise low-intensity shivering.
abstract: Exercise and shivering rely on different metabolic pathways and consequently, fuel selection. The present study examined the effects of a pre-exercise low-intensity shivering protocol on fuel selection during submaximal exercise in a cold environment. Nine male subjects exercised 4 times for 60 min at 50% (LOW) or 70% (MOD) of their peak oxygen consumption on a motorized treadmill in a climatic chamber set at 0 °C with (SHIV) and without (CON) a pre-exercise cooling protocol, inducing low-intensity shivering. Thermal, cardiorespiratory and metabolic responses were measured every 15 min whereas blood samples were collected every 30 min to assess serum nonesterified fatty acids (NEFA), glycerol, glucose, β-hydroxybutyrate (BHB) and plasma catecholamine concentrations. Rectal and skin temperatures were lower in the SHIV condition, within LOW and MOD conditions, during the first 45 min of exercise. Norepinephrine (NE) concentration was greater in SHIV vs. CON within LOW (1.39 ± 0.17 vs. 0.98 ± 0.17 ng·mL(-1)) and MOD (1.50 ± 0.20 vs. 1.01 ± 0.09 ng·mL(-1)), whereas NEFA, glycerol and BHB were greater in SHIV vs. CON (1060 ± 49 vs. 898 ± 78 μmol·L(-1); 0.27 ± 0.02 vs. 0.22 ± 0.03 mmol·L(-1); 0.39 ± 0.06 vs. 0.27 ± 0.04 mmol·L(-1), respectively) within MOD only. No changes were observed in fat or carbohydrate oxidation between SHIV and CON during exercise. Despite increases in NE, NEFA, glycerol and BHB from pre-exercise low-intensity shivering, fuel selection during short-term submaximal exercise in the cold was unaltered.
authors.affiliation: a Department of Biology of Physical Activity, P.O: Box 35, University of Jyväskylä, Jyväskylä FI-40014, Finland.
authors.forename: Dominique D
authors.initials: DD
authors.lastname: Gagnon
authors.forename: Hannu
authors.initials: H
authors.lastname: Rintamäki
authors.forename: Sheila S
authors.initials: SS
authors.lastname: Gagnon
authors.forename: Juha
authors.initials: J
authors.lastname: Oksa
authors.forename: Katja
authors.initials: K
authors.lastname: Porvari
authors.forename: Stephen S
authors.initials: SS
authors.lastname: Cheung
authors.forename: Karl-Heinz
authors.initials: KH
authors.lastname: Herzig
authors.forename: Heikki
authors.initials: H
authors.lastname: Kyröläinen
mesh_terms: D003080:Cold Temperature; D004734:Energy Metabolism; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test / Q000379:methods*; D006801:Humans; D008297:Male; D012768:Shivering; D013997:Time Factors; D055815:Young Adult