Saliva samples are collected before other testing begins to establish a baseline measure of deuterium in the saliva. An amount of pure D2O is weighed, measured, and added to de-ionized water which is given to participants to drink. After a two hour fast and no urine eliminations, another saliva sample is taken and the amount of D2O remaining in the saliva is measured. Fasting blood samples are collected on participants by a venous draw. Samples are also taken to determine the levels of the hormones DHEA SO4, estradiol, free testosterone, total testosterone, and insulin within participants between the ages of 8 and 18 and in females over 40.
Blood pressure is monitored and recorded on all participants.
Grip strength on both hands is recorded. Hand radiographs of the participants from age 8 through 18 are also taken. These radiographs are assessed to determine the skeletal ages of the individual and are scored through various established skeletal maturation assessment procedures . Other data is also gathered through the use of questionnaires. Surveys are filled out by the participants to find out medical history, physical activity, tobacco and alcohol use, sexual maturity, and for females, menstrual history.