The Effects of β-Hydroxy-β-methylbutyrate Free Acid Gel and High-Intensity Interval Training on Quadriceps Muscle Architecture and Quality, Neuromuscular Economy, and Metabolic Performance in Recreationally Trained Individuals

Objectives: 1) Determine the effect of 4-weeks of high intensity interval training (HIIT) and free acid form β-Hydroxy-β-methylbutyrate (HMB-FA) on VO2peak, lactate threshold, critical power, anaerobic working capacity and neuromuscular economy in a population of endurance trained individuals. 2) Determine the effect of 4-weeks of HIIT and HMB-FA on changes in skeletal muscle physiological cross-sectional area (PCSA=Volume/Fascicle length) and muscle quality (MQ=echo intensity) in the rectus femoris and vastus lateralis.

Subjects: Fifty males and females between the ages of 18 - 35 will be recruited to participate in this study. Subject will be randomized to one of three groups: a control group (CTL), an HIIT only group (HIIT) or a group which will take the amino acid metabolite HMB and perform HIIT (HMB-HIIT). Individuals assigned to CTL will undergo baseline testing. They will then be asked to continue their normal exercise routine for 4 weeks and will undergo post-testing after this time period.

Study Protocol: Two testing sessions, on nonconsecutive days, will occur at least 72 hours prior to the start of the training period. The same testing protocols will be repeated at the end of the 4-week training period. Testing protocols include performance testing (VO2peak, lactate threshold, critical power, anaerobic working capacity and neuromuscular economy) and anthropometric measures (physiological cross-sectional area and muscle quality). The training protocol for individuals in the experimental groups will consist of 4-weeks of high intensity interval training with three sessions per week on an electronically braked cycle ergometer. Individual work -loads will be calculated based on the outcomes from each participant's preliminary testing.