STATE OF TRAINING: A DETERMINANTS OF ENERGY EXPENDITURE DURING WEIGHT-TRAINING? 764

Abstract

The contribution of anthropometrical and physiological variables in the inter-individual differences in energy expenditure (EE) during weight-training was determined using a standardized training protocol. The experimental group consisted of 10 trained (TR) and 14 untrained (UNTR) male subjects. Subjects performed 6 computer-paced weight-training sessions using standard weights (42 min; 10 exerc., 3×15 reps, work:rest=1:1). Session 1 and 2 were used to accommodate. During sessions 3-6 respiratory gas-exchange was continuously measured and converted to EE. In sessions 5 and 6 training weights were raised with ±50%. Variables included in the analysis were: Age, Body mass(BM), Body composition (%FAT, hydrostatic weighing), Isokinetic muscular strength during chest press (PRESS) and leg extension (EXT; Cybex II), and Sleeping metabolic rate (SMR, respiration chamber). A bivariate correlation analysis performed on the average EE of all four sessions (22.2 ±2.6 kJ/min) revealed a significant relationship (Pearson corr. coeff.) with BM(.58) and%FAT (.50). Multiple regression analysis including all six variables, revealed that more than half of the inter-individual variation in EE could be explained by differences in BM (33%) and PRESS (20%). The effect of BM could be expected since 50% of the exercises were weight bearing. There were no differences in BM between TR and UNTR whereas PRESS differed significantly(399 versus 299 Nm, P<.001), most likely due to training. To examine whether state of training was a determinant an ANOVA on EE during weight-training was performed including BM as a covariate. This analysis revealed a significant difference in EE between TR and UNTR (20.8 ±2.3 versus 23.3 ±2.4 kJ/min, respectively). In conclusion: State of training was a determinant of EE during weight-training, most likely due to differences in muscular strength and therefore training intensity.