To quantify day-to-day variability in energy expenditure (EE) during weight-training, 10 male subjects completed 6 training sessions that consisted of a warming-up and cooling-down phase (10 min; arm cranking or cycling) and a computer-paced weight-training phase using standard weights (42 min;; 10 exercises, 3x15 repetitions, work to rest ratio = 1:1). The first 2 sessions were used to accommodate. During sessions 3-6 (labeled session A, B, C and D) cardiorespiratory response was continuously measured. Gas-exchange was converted to EE using the Weir formula. In the last two sessions training weights were raised by ±50 % and the initial warming-up and cooling-down exercise being arm-cranking was replaced by cycling. Mean EE was calculated for last five minutes of the warming-up (WU5) and cooling-down (CD5) and the complete weight-training phase (WT). Mean EE during WT for session A to D was 20.0 ± 2.7, 19.1 ±2.5, 22.2 ± 2.2 and 21.9 ± 2.4 kJ · min-1, respectively. Daily variation was tested by comparing test-retest phases (A vs B and C vs D). Intra-individual variability in EE during respectively the lower (session A vs B) and higher (session C vs D) weight -training intensity was expressed as: absolute test-retest difference (0.9 + 0.5 and 0.7 ± 0.6 kJ min-1), difference relative to the mean of the test-retest measurements (2.3 ± 1.4 and 1.6 ± 1.4 %) and as the mean coefficient of variation (3.3 and 2.2 %). There were no differences in variability between both WT-intensities or exercise modes, irrespective of the way variability was expressed. In conclusion, intra-individual variability in EE during weight-training does not differ from variability during arm cranking or cycling.
Key words
Cardiorespiratory response - indirect calorimetry - day-to-day variation - coefficient of variation - recovery energy expenditure
