Vill passa på att be om ursäkt för ett något rörigt inlägg.
Protein används knappt som bränsle. I övrigt är det som sagt fett som används primärt, för att ge lite belägg kommer här lite referenser till vetenskapen:
Från Henriksson, J. (1995)
" UTILIZATION OF B L O O D - B O R N E A N D E N D O G E N O U S LIPIDS It is known from a large number of studies that, at the same absolute exercise intensity, trained individuals rely more on fat as an energy substrate than untrained ones "
" During exercise at low to moderate intensities plasma NEFA may often cover more than half the muscle’s oxidative metabolism, especially during prolonged exercise (Ahlborg et al. 1974), but its importance diminishes as the exercise intensity increases. "
Dvs mer än hälften av bränslet för en typ av fett.
Från: Jean-Michel Weber (2004)
I ovan artikel bidrar man med en rätt bra överskådlig tabell över hur energikällorna ser ut på sida 24. Fett dominerar upp till ca 55% av vo2max (motsvarar väl cirka 65% av maxpulsen dvs generellt zon 2).
Från Bettina Mittendorfer (2003)
" The relative contribution of carbohydrate and fat as fuel for working muscle is largely dependent on exercise intensity and duration. Fat is the predominant source of fuel during prolonged low- and moderate-intensity exercise (up to about 65 % of maximal O2 consumption; VO2max) (Jones et al. 1980; Romijn et al. 1993; van Loon et al. 2001); as exercise intensity increases there is a progressive decline in fat oxidation and the relative oxidation of carbohydrate increases (Jones et al. 1980; Coggan, 1991; Romijn et al. 1993; van Loon et al. 2001).
Övrigt:
Vill du slippa läsa vetenskapliga artiklar kan du ju bara dra in på denna länk:
How the body uses fat and carbohydrates during exercise is a hotly debated concept in the fitness industry right now and, frankly, this puzzles me. The research over the past 30 years has borne out exactly how our bodies use carbohydrates, proteins, and fat during different exercise intensities...
macrosinc.net
Som enkelt sammanfattat en väldigt intressant artikel (
https://pubmed.ncbi.nlm.nih.gov/8214047/)
" If you are training at the lower level intensity, you utilize mostly free fatty acids."
Även:
https://www.cooperinstitute.org/2016/06/02/fuel-use-during-exercise-myths-and-misconceptions
Här hävar man att fett står för 52% av energiförbrukningen under lågintensiv träning.
Referenser:
Jean-Michel Weber, François Haman (2004)Oxidative fuel selection: adjusting mix and flux to stay alive, International Congress Series, Volume 1275, Pages 22-31,
https://doi.org/10.1016/j.ics.2004.09.043 (
https://www.sciencedirect.com/science/article/pii/S0531513104015432)
Henriksson, J. (1995). Muscle fuel selection: Effect of exercise and training.
Proceedings of the Nutrition Society, 54(1), 125-138. doi:10.1079/PNS19950042
Muscle fuel selection: effect of exercise and training - Volume 54 Issue 1
www.cambridge.org
Mittendorfer, B., & Klein, S. (2003). Physiological factors that regulate the use of endogenous fat and carbohydrate fuels during endurance exercise.
Nutrition Research Reviews, 16(1), 97-108. doi:10.1079/NRR200357