## 1 Introduction  
Weight training is an important type of exercise for the elderly, general, and athletic populations and is used to enhance body composition along with other aspects of health and performance [1, 2]. More specifically, it can reduce body fat, lower blood pressure, enhance cholesterol levels, promote glycemic control, and generally decrease the risk of heart disease [3, 4]. As weight training is included as one of the main exercise programs to increase energy expenditure (EE), it should target the large major muscle groups [4, 5, 6]. The recommended dose of weight training exercise for a healthy life for all age groups is two or more days per week [4].  
Total EE (TEE) is composed of the basal metabolic rate (BMR or basal EE (BEE)) and is equivalent to approximately 60-75% of TEE, activity EE (AEE) is about 15-30% of TEE, and dietary thermogenesis is about 10% of TEE [7,8]. TEE, BEE, and AEE vary over time and differ between sexes, with values for males often higher than those of females, and values for older people are lower than those for younger people [9]. Different disease conditions may have an effect on TEE and AEE [10]. In addition, since the AEE is the most variable component of TEE, it is often used to assess TEE [11, 12, 13]. Doubly labeled water is the gold standard to assess TEE because of its high degree of accuracy, and indirect calorimetry is commonly used to track EE in healthy and diseased people over time [14] during physical activity.  
The metabolic equivalent (MET) is a functional unit of oxygen consumption during exercise [15, 16, 17]. According to the Centers for Disease Control and Prevention (CDC)/ American College of Sports Medicine (ACSM) and the Compendium of Physical Activities, 1.6-2.9 METs is considered light intensity, 3.0-5.9 METs is considered moderate intensity, and >6.0 METs is considered vigorous intensity of aerobic exercise [1,18]. Resistance training (RT) is described as 3.5 METs (code 02054) and/or 5.0 METs (code 02052) in the Compendium of Physical Activities [18], with EE ranging from 5 to 10 kcal/min (for men of an average height and weight, this is equivalent to 135-270 kcal). Previous research [15, 16, 17] focused on RT using a training machine and/or free weights with high loads. Moderate-intensity exercises using dumbbells, such as the bent-over row, deadlift, and lunge can be performed as free weight exercises.  
In the previous literature, many studies have reported the EE of acute or chronic resistance exercise, but to our best knowledge, no study has compared energy costs and physiological profiles of the dumbbell bent-over row, deadlift, and lunge exercises together with rest intervals in one training session. As these exercises use multiple groups of large muscles in the upper and lower body, they may provide benefits of fitness and muscle gain. In addition, this study focused on healthy individuals' weight training so that EEs could be compared between two populations of naive and experienced weightlifters to generalize the study findings for healthy and athletic populations. In RT, pulling or pushing is usually performed rapidly, but in this study, the same speed of 2 s was used for the pulling and pushing phases. In addition, dumbbells serve as free weights with a higher degree of freedom and increased challenge to exercised muscles. Therefore, the main objectives of this study were twofold: (1) to compare the energy cost of each weight training exercise (the dumbbell bent-over row, deadlift, and lunge) between the two groups to determine if the exercises belong to moderate or high intensity at 60% of one-repetition maximum (RM) loading and (2) to compare physiological parameters during these three weight training exercises. The results of this study can be used to determine an exercise protocol that can be utilized for fitness and conditioning purposes in healthy populations.