I agree with Karin that there are multiple definition of exercise depending on who you ask what class you take or what a researcher’s bias is. From a graduate exercise physiology class taken fall quarter 2012:
From the physiological perspective, it is useful to think about what the essential factor is that makes something exercise. I think it is contractions of skeletal muscles. Skeletal muscles exert force to (a) cause movement of the body or a body segment (e.g., lifting a weight, running, swinging a bat), (b) resist movement (e.g., lowering a weight, absorbing a hit in football, catching an object), or (c) prevent movement (e.g., holding the iron cross position on the rings in gymnastics, holding a football lineman’s stance until the ball is snapped). It is the muscle contractions that do the activity we call exercise; without muscle contractions we don’t do any exercise. Muscle contractions are fundamental. Then, a lot of other things have to happen in the body to support the muscular activity: adjustments of the heart’s function, circulation of the blood, lung function, etc.
I am not sure your will be able to find that ‘most recent’ definition. The term ‘exercise’ in not one where new science reveals additional information which requires an update to the definition.
A google search will provide you with a variety of options as far as wording is concerned.