A Study of the Effect of BIIB023 on Muscle Atrophy in Healthy Male Volunteers

Key Inclusion Criteria: * Deemed healthy as determined by the Investigator based on medical history, 12-lead electrocardiogram, vital signs, and clinical laboratory parameters at Screening, and physical examination at Baseline * Body mass index (BMI) between 18.5 and 32 kg/m2, inclusive, at the time of Screening * Willing to abstain from using tobacco and tobacco-containing products during the study * Willing to limit the intake of alcohol to no more than 2 units per day throughout the study; exceptions are 48 hours prior to Screening, 48 hours prior to Day 1, and during the in-clinic immobilization period when no alcohol will be permitted. One unit of alcohol is defined as 12 fluid ounce (fl oz) of beer, 5 fl oz of wine, or 1.5 fl oz of liquor * Willing to maintain a regular diet for the duration of the study and a recreational level of physical activity defined as participation in an exercise program or other physical activity at a level of intensity that does not exceed the level prior to study entry * Practice effective contraception during the study and be willing and able to continue contraception for at least 6 months after the last dose of study treatment. Key Exclusion Criteria: * History of or positive test result at Screening for human immunodeficiency virus (HIV). * History or positive test result at Screening for hepatitis C virus (HCV) antibody or hepatitis B virus (defined as positive for hepatitis B surface antigen \[HBsAg\] or hepatitis B core antibody \[H…