Skeletal muscle comprises the largest organ system in the human body and is essential for force generation and movement. Skeletal muscle is subjected to considerable stresses during everyday use. However, muscle has the unique ability to adapt and remodel to provide protection against such stresses. This adaptation occurs at the structural through to the cellular level, which includes changes in transcription of a range of protective proteins. Failure in such processes can be catastrophic. This failure in adaptation is particularly notable in older individuals. Our skeletal muscles become smaller and weaker as we age. This loss of muscle bulk results in a reduced capacity to generate force and results in a loss of the ability to undertake everyday tasks. This article describes the normal adaptive responses of muscle in younger individuals to the stress of various forms of exercise and the implications of a failure of these adaptive responses in the elderly.