**8. Testing pearls and pitfalls**

Neuroimaging studies are expensive. Exercise testing and training are expensive. Recruitment drop-outs are expensive. And botched tests are expensive. They are expensive in terms of time, money and patience. Neuroimaging and exercise testing aged individuals bring a unique set of challenges to intervention research. There are the standard safety issues to consider when using a neuroimaging technique or conducting a physical exercise test; but the less obvious issues of comfort and trust sometimes slip by unasked, until it is too late and the subject has dropped out of the study. Therefore, when screening an older individual for an imaging and/or an exercise study, the following question must be asked: can the volunteer complete the testing protocol accurately and in relative comfort? The researcher must ascertain that the older volunteer can hear, see, follow directions, and adhere to the instructions. Volunteers must be able to complete enough of the exercise protocol to get valid physiological baseline data and/or remain motionless and pain free in the MRI scanner anywhere from 15 to 120 minutes. The brief breaks afforded between imaging sequences when a subject is free to move slightly may be insufficient. Arthritis, nasal-sinus drainage, and circulatory issues have thwarted many research MRI scans. For a first-time MRI scan, volunteers may back out at the last minute due to unanticipated fright (hence a simulator is an invaluable resource) or the irrational worry that the MRI will read their minds (thanks to outlandish media stories). Thus, the researcher must design protocols with both the science and the targeted subject population in mind.
