The term 'LASTING POWER' can be broken down into two crossword solutions: LEGS (4 letters) and STAMINA (7 letters). LEGS are the lower limbs of the human body, which are used for walking, running, and other activities. STAMINA is the ability to sustain physical or mental effort over a long period of time. Together, these two solutions represent the lasting power of the human body, which is the capacity to endure physical and mental exertion for an extended period of time.