The purpose of this investigation was to study the relationship between exercise intensity and weight training economy. Seven subjects performed squat and seated behind the neck press exercises at 60% and 80% of one repetition maximum (1 RM). Addition of net exercise oxygen uptake (VO2) to net recovery VO2 provided an estimate of metabolic cost for the exercise. Estimation of work performed was accomplished by calculation of vertical external work (VEW). Weight training economy was calculated (weight training economy = kcals consumed x VEW-1). The squat was significantly more economical than the overhead press (p = 0.002), and exercise at 60% 1 RM was more economical than exercise at 80% 1 RM (p less than 0.001). Correlations between VEW and kcals consumed at each intensity ranged between 0.85-0.98. It was determined that estimation of metabolic cost of weight training exercise must take into account not only the vertical external work accomplished, but also the intensity of the exercise (% 1 RM). Vertical external work performed on the bar appears to be as accurate as the total vertical external work value in prediction of metabolic cost of the squat and overhead press exercises. Use of the weight training economy values obtained in this study for prediction of metabolic cost will provide values with 4.2%-15.8% prediction error.