As the respiratory exchange ratio
increases, it means glucose (carbohydrates) rather than fat is starting to be used as a fuel source.
Oxygen uptake (V[O.sub.2], panel A), carbon dioxide output (VC[O.sub.2], panel B), ventilation (VE, panel C), and respiratory exchange ratio
(RER, panel D) responses during the 30/30 s and the 60/60 s low-volume high-intensity interval training (LV-HIIT) protocols.
(12) maximal effort criteria were adopted: (a) V[O.sub.2] plateau (increase [less than or equal to]150 mL*[min.sup.-1] or 2 mL*[kg.sup.-1]*[min.sup.-1]); (b) respiratory exchange ratio
(RER) [greater than or equal to]1.15; (c) 90% of the HR max predicted by the age (220 - age); (d) effort perception concept [greater than or equal to]19 (5); and (e) maximal volitional fatigue with incapacity to support the ride cadence.
V[O.sub.2], respiratory exchange ratio
(RER), and minute ventilation (VE) were determined by averaging data from the last minute of each exercise stage, during which subjects were assumed to be at steady-state.
The measurement of the respiratory exchange ratio
(RER) (VCO2/VO2) gives an indication of the major source or proportion of calories consumed: protein, or carbohydrate, or fat.
carbohydrate, we should look at the respiratory exchange ratio
The exercise was considered to be maximal when three of the following criteria were obtained (Edvardsen et al., 2014; Poole et al., 2008): i) levelling off V[O.sub.2] ii) HRmax > 90% theoretical HR max (Hansen et al., 1984) iii) respiratory exchange ratio
RER was greater than 1.15 iv) pedal rate < 50 rpm v) volitional exhaustion.
Oxygen uptake (V[O.sub.2]) and respiratory exchange ratio
(RER) were determined by indirect calorimetry using a Parvo Medics TrueOne 2400 Metabolic Measurement System (ParvoMedics, Sandy, Utah), which was also used to calculate EE (kilocalories).
Additionally, the mean of respiratory exchange ratio
(RER) in effort ([RER.sub.effort]) and pause ([RER.sub.pause]) was used.
No differences (P>0.05) were found between groups for resting BP and HR, peak V[O.sub.2], minute ventilation ([V.sub.E]), respiratory exchange ratio
(RER), and tidal volume ([V.sub.T]).
The primary aim was to evaluate the hypothesis that a short term (4-9 days) low-PRAL diet results in a higher respiratory exchange ratio
during maximal exercise as compared to that after a high-PRAL diet.
In this exercise intensity, the value of the respiratory exchange ratio
(RER) is approximately 1.00.