Throughout my personal training career I’ve often been requested to include extra exercises that stimulate a certain area of the body where the client wants to lose fat. This is commonly referred to as “spot training.” For example, someone may carry a lot of fat in their midsection and therefore request a lot of abdomen exercises, hoping to reduce fat localized in that area. Perhaps the rationale is that when they are doing these exercises they feel a burning sensation localized to the abdomen and that in some way increases the fat-burning effect in that area. This truly highlights the need for increased educationin regard to human physiology. It would likely take many polls and studies to truly understand the root of this misconception, so instead of exhausting the topic of why people believe spot training to be true I will simply explain what is happening during certain types of exercises and explore the literature in regards to spot training.
A possible area for confusion may be that fat loss is often referred to as “burning fat.” It may be that the crossover in terminology has aided in the misconception. During high-intensity, short-duration exercise our bodies rely on anaerobic glycolysis for ATP production. These processes result in an accumulation of metabolites such as lactate, hydrogen ion, inorganic phosphate, creatine and others (Schoenfeld, 2010). Hydrogen ion accumulation especially leads to the “burning” sensation that is felt during intense exercise. But, the accumulation of these metabolites do not trigger lipolysis of subcutaneous fat stores in that specific area.
Although high-intensity exercise can aid in fat loss, creating a negative energy balance ultimately determines whether or not fatty acids are mobilized from fat depots at all (Ramirez-Campillo et al., 2013). Achieving a negative energy balance comes from reducing caloric intake to a level that is lower than the subject’s total daily energy expenditure (TDEE), by increasing TDEE while maintaining caloric intake, or a combination of the two. When negative energy balance is achieved, especially through exercise, the body will alter the body’s hormonal environment. Hormones such as adrenaline that are released during exercise promote fatty acid mobilization from fat depots and, consequently, subcutaneous fat reduction (de Glisezinski et al., 2009). It should be noted that this altered hormonal environment is not localized to the exercised muscle group. The effect takes place in the entire body due to the modality of transportation being through the blood.
A study by Ramirez-Campillo et al. (2013) had subjects perform the leg press only with their non-dominant leg for 80 minutes, 3 sessions per week. The weight was between 10-30% of their 1RM, and the subjects would perform between 960-1200 repetitions per session. This amount of volume resulted in a significant calorie burn that resulted in a negative energy balance, although the subjects maintained their regular caloric intake. It was found that the subjects saw significant regional fat loss, but no difference was found between legs. In fact, there was no significant reduction in fat mass in the leg region at all, which undermines the idea of spot reduction. Interestingly, the subjects saw greater degrees of fat reduction to the trunk and arms than any other region of the body. It was theorized that this was due to the subjects carrying greater percentages of their body fat in these regions, thus having more to lose. Performing an exercise for 80 minutes and at that low of an intensity would be more aerobic than anaerobic, and was likely an intention of the authors. Undergoing a training stimulus that would elicit significant enough calorie burn that localized fat loss could be seen, if it was going to happen at all. This design may be due to previous research using more anaerobic exercises that were higher intensity and shorter duration, but I appreciate seeing experimental designs that target different energy systems in order to answer the question of whether or not energy system targeting was the design flaw that led to the outcome.
A study with lower total exercise duration was performed by Katch et al. (1984) and found that 27 days of abdominal muscle training did not increase abdominal fat mobilization. The participants started by doing 10 sets of 7 sit-ups with 10 second rest intervals on day one. By day 27 they were performing 14 sets of 24 sit-ups with 10 second rest intervals as well. Although the intensity of a sit-up exercise coupled with these short rest times isn’t entirely anaerobic either, it was likely more so than performing a leg press for 80 minutes. I would consider this to be more “middle of the road” in terms of utilization of our body’s aerobic and anaerobic energy systems.
Research by Kostek et al. (2007) was a study that favored anaerobic exercise design. Researchers had 104 participants perform 5 arm exercises (3 bicep, 2 tricep) only on the non-dominant arm. Participants performed 3 sets of 12 reps at an intensity of 65-75% 1RM. This was followed by a 2 minute break time which is an acceptable amount of time for anaerobic energy recovery. This was done with a frequency of 2 sessions per week, allowing 48 hours of rest between sessions. Researchers showed that 3 months of training the non-dominant arm resulted in muscle increases to the trained arm but no differences between arms in subcutaneous fat loss.
These are just a few of many studies that have repeatedly called into question the practice of spot training. It has been demonstrated that localized and targeted fat reduction is absent, even despite various training modalities and designs. Given the state of current research it can be confidently concluded that spot training for localized fat loss is unfounded and untrue. Persons seeking fat reduction in any area of the body should emphasize achieving and maintaining a negative energy balance throughout appropriate durations and within reasonable quantities. A final note is that this should not be viewed as a deterrent to resistance training of certain body parts, but rather a focus of purpose and intention. Although the exercise may not reduce localized fat, it can lead to muscle growth which will present a much more aesthetic product, once the subcutaneous fat is reduced sufficiently enough to reveal it.
References
de Glisezinski, I. , Larrouy, D. , Bajzova, M. , Koppo, K. , Polak, J. , Berlan, M. , Bulow, J. , Langin, D. , Marques, M. A. , Crampes, F. , Lafontan, M. & Stich, V. (2009). Adrenaline but not noradrenaline is a determinant of exercise-induced lipid mobilization in human subcutaneous adipose tissue. Journal of Physiology, 587(13), 3393–3404. doi: 10.1113/jphysiol.2009.168906.
Katch, F., Clarkson, P., Kroll, W., McBride, T., & Wilcox, A. (1984). Effects of sit up exercise training on adipose, cell size and adiposity. Research Quarterly for Exercise & Sport, 55(3), 242–247.
Kostek, M. A., Pescatello, L. S., Seip, R. L., Angelopoulos, T. J., Clarkson, P. M., Gordon, P. M., Moyna, N. M., Visich, P. S., Zoeller, R. F., Thompson, P. D., Hoffman, E. P., & Price, T. B. (2007). Subcutaneous fat alterations resulting from an upper-body resistance training program. Medicine & Science in Sports & Exercise, 39(7), 1177–1185.
Ramirez-Campillo, R., Andrade, D. C., Campos-Jara, C., Henriquez-Olguin, C., Alvarez-Lepin, C., & Izquierdo, M. (2013). Regional fat changes induced by localized muscle endurance resistance training. Journal of Strength & Conditioning Research, 27(8), 2219–2224.
Schoenfeld, B. J. (2010). The mechanisms of muscle hypertrophy and their application to resistance training. The Journal of Strength and Conditioning Research, 24(10), 2857-2872.