Interaction of Beta-Hydroxy-Beta-Methylbutyrate Free Acid and Adenosine Triphosphate on Muscle Mass, Strength, and Power in Resistance-Trained Individuals

Abstract

To The Editor: We have recently become aware of the article by Lowery et al. in J Strength Cond Res 30(7): 1843–1854, 2016 entitled “Interaction of Beta-Hydroxy-Beta-Methylbutyrate Free Acid and Adenosine Triphosphate on Muscle Mass, Strength, and Power in Resistance-Trained Individuals.” We have some thoughts regarding the Methods and Results sections of the article for the readership of JSCR to consider. Methodological Questions Minimal difference values were not provided for body composition variables determined by DXA. Could the authors provide ICC's, along with the SD values for lean body mass (LBM) and fat mass (FM) so that minimal difference can be determined? The authors fail to provide any citation for location of ultrasonography for assessment of skeletal muscle hypertrophy. Were records kept for total training volume completed during the intervention for each group? Was volume and load equated across groups? Results Comments We realize that one earlier study demonstrated similar findings as that of this study; however, the Kraemer et al. (1) study used less-trained subjects, as well as a multiingredient supplement containing HMB-Ca. This study also found significant elevations in postexercise testosterone levels, whereas this study did not. Could the authors expand on the potential mechanisms responsible for muscle growth (highlighting the form and dose of HMB used in this study compared with previous studies)? We are curious about the increase in LBM (8.5 kg) and significant decrease in FM observed in the resistance-trained population used. The increase in LBM is somewhat shocking, especially when compared with previous literature using HMB in athletic populations (2–4). Further explanation as to how or why these robust changes occurred would certainly benefit the reader. If no sound explanation can be made, could there have been possible errors with the DXA machine or how the data were analyzed/reported? This might help to explain why—for the most part—these authors are the only ones who have found such significant improvements in body composition after HMB and ATP supplementation (5,6). Conclusion Owing to inconsistencies in findings between this study and that of data previously published from other laboratories, we strongly encourage researchers to replicate this study in an attempt to discover comparable findings. Furthermore, the authors mention an increase in blood flow and/or an increase in training volume as possible mechanisms for muscle growth, but blood flow was not measured and training volume was not reported. We suggest future research aim to measure or track these variables to provide possible explanations for improvements in strength and body composition after HMB + ATP supplementation. In addition, we recommend measuring growth hormone and insulin-like growth factor to determine possible underlying mechanisms for the significant increases in LBM.