April 22, 2017
Roberson, Kirk1; Jacobs, Kevin A.1; White, Morgan1; Signorile, Joseph F., 2
1Laboratory of Neuromuscular Research & Active Aging-University of Miami, Coral Gables, FL
2 University of Miami-Miller School of Medicine, Center on Aging
Circuit resistance exercise has become an increasingly popular method for training and generally involves the use of high-intensity intervals with minimal recovery periods. Many people are adopting circuit training because high-intensity workouts require a shorter time commitment than traditional weight training or aerobic training programs. There is an abundance of research which suggests that if employed properly, high-intensity interval training can be more effective than traditional resistance or aerobic exercise in increasing cardiorespiratory fitness and increasing energy expenditure. Additionally, many commercial, military, and private fitness facilities regularly incorporate circuit exercise into their training models. However, there is little information concerning how variations in weight, movement speed, and recovery intervals impact the rate of caloric expenditure and the overall caloric cost of this specific form of interval training, which uses both weight and movement speed to increase intensity during a workout.
This study included 15 men and women ranging in age from 18-24 years. It compared the effects of using (1) a moderate load (50% of one repetition maximum (1RM): a load that generally allows the completion of 12-20 repetitions) done explosively; (2) and a heavy load (80% 1RM: that allows the completion of about 6-8 repetitions) done explosively; or (3) a heavy load with two second concentric and eccentric motion. Explosive movements were defined as maximal perceived speed during the concentric phase and a two-second eccentric phase. All participants completed each protocol on separate days. A wide range of exercises targeting all major muscle groups were completed on pneumatic resistance machines. Caloric expenditure was assessed using a portable metabolic unit. Data were collected during a 15 minute baseline rest period, throughout each workout cycle, and for 30 minutes following the training session. In an effort to quantify the contributions of the anaerobic energy systems to total energy expenditure and rate of energy expenditure, blood lactate was measured before and immediately following each circuit.
Both explosive exercise protocols resulted in greater total caloric expenditure than exercises completed using controlled movements. The explosive protocols also resulted in a faster rate of caloric expenditure than the controlled movement protocol, with explosive movements using a heavy load resulting in the highest rates. Although rest periods were not dictated, on average, participants rested about 25s between exercises with no significant differences between protocols. Our finding that explosive movements resulted in a greater energy expenditure may help individuals whose goal is to maximize energy expenditure especially when time is a limiting factor. A final benefit with this type of training is its potential to increase muscular strength and power above standard interval training techniques.
This article is a summary of an article published in Applied Physiology, Nutrition & Metabolism. If you intend to cite any information in this article, please consult the original article and cite that source. This summary was written for the Canadian Society for Exercise Physiology and it has been reviewed by the CSEP Knowledge Translation Committee.
Roberson KB, Jacobs KA, White MJ, Signorile JF (2017). Loads and Movement Speed Affect Energy Expenditure during Circuit Resistance Exercise. Appl Physiol Nutr Metab. [Epub ahead of print]. doi: 10.1139/apnm-2016-0552