Experimental protocol
In a randomized, placebo‐controlled, double‐blind (for both participant and experimenter and for both caffeine and carnitine administrations) trial, participants arrived at the laboratory on three occasions at 11:00 having followed a controlled diet the evening prior (900 kcals; 20/25/55% fat/protein/CHO, respectively) and for breakfast (600 kcals; 20/25/55% fat/protein/CHO, respectively), with all food provided by the research team for consumption at home with appropriate instruction. These laboratory visits were to conduct three randomly assigned, counterbalanced (order) experimental test days: (1) carnitine only (CARN); (2) caffeine only (CAFF); (3) carnitine + caffeine (CARN + CAFF). Participants rested in a semi‐supine position on a bed for the 5 h duration of each experimental test day. Prior to the start of the experiment, two cannulas were placed; (1) retrogradely into a dorsal hand vein of the non‐dominant hand for arterialized venous blood sampling (Gallen & Macdonald, 