Purpose: It is believed spot reduction, the exercise-induced localized loss of subcutaneous fat, does not occur as a result of an exercise program; however, evidence as a whole has been inconsistent. To reexamine this concept, we compared subcutaneous fat measurements before and after resistance training among 104 subjects (45 men, 59 women).
Methods: Subjects participated in 12 wk of supervised resistance training of their nondominant arm. Magnetic resonance imaging and skinfold calipers examined subcutaneous fat in the nondominant (trained) and dominant (untrained) arms before and after resistance training. Repeated-measures ANCOVA tested for subcutaneous fat differences within and between arms before, after, and from before to after resistance training by gender and measurement technique, with BMI and age as covariates. Simple linear regression compared subcutaneous fat changes before and after resistance training as assessed by MRI and skinfold.
Results: Subcutaneous fat, measured by skinfold, decreased in the trained arm and not the untrained arm in the men (P < 0.01); it was similar in the total sample and in the women (P > 0.05). MRI determinations of subcutaneous fat changes were not different between arms in the total sample and by gender (P > 0.05).
Conclusion: Subcutaneous fat changes resulting from resistance training varied by gender and assessment technique. Skinfold findings indicate that spot reduction occurred in men but not in women. In contrast, MRI found a generalized subcutaneous fat loss independent of gender, supporting the notion that spot reduction does not occur as a result of resistance training. MRI, sensitive to changes along the entire upper arm, detected greater variation in resistance training responses, preventing significant differences between trained and untrained arms. Variation in upper-arm resistance training response was not evident from a single skinfold measurement at the belly of the muscle.
1Department of Kinesiology, University of Connecticut, Storrs, CT; 2Division of Cardiology, Henry Low Heart Center, Hartford Hospital, Hartford, CT; 3Department of Health Professions and Center for Lifestyle Medicine, University of Central Florida, Orlando, FL; 4Department of Exercise Science, Totman Building, University of Massachusetts, Amherst, MA; 5Division of Exercise Physiology, School of Medicine, West Virginia University, Morgantown, WV; 6Department of Sport Science and Health, Dublin City University, Dublin, IRELAND; 7Human Performance Laboratory, Central Michigan University, Mount Pleasant, MI; 8Department of Exercise Science and Health Promotion, Florida Atlantic University, Davie, FL; 9Research Center for Genetic Medicine, Children's National Medical Center, Washington, DC; and 10Department of Diagnostic Radiology, Yale University School of Medicine, New Haven, CT
Address for correspondence: Matthew A. Kostek, M.S., Graduate Assistant, University of Connecticut, Department of Allied Health Sciences, 358 Mansfield Road, U-2101, Storrs, CT 06269-2101; E-mail: Matthew.firstname.lastname@example.org.
Submitted for publication August 2006.
Accepted for publication March 2007.