Disuse may consist of decreased strength, muscular endurance, bone health, muscle atrophy (decreased muscle size), etc. This may be due to several factors including but not limited to, immobilization (such as having a cast on a limb), sedentary behavior (such as desk jobs or choosing to drive to walk-able locations), consciously or unconsciously favoring one body part over another for certain activities (opposite of over-dependence/overuse), etc.
Misuse consists of the improper use of various components or systems of the body. One major form of misuse is improper breathing technique. In my experience, about nine of every ten patients I see have an improper breathing pattern. This is no fault of each person per se, but is rather a trend resulting from the direction our westernized habits have taken us. Prolonged poor sitting postures, constant bombardment of stimuli on our nervous systems, the chronic use of various drugs (prescription, over-the-counter, and other consumables such as caffeine and alcohol) all have affected how our body carries out its breathing process. Our habits have trended towards the increased dependence on the use of what are termed "accessory muscles of respiration". Without getting too side tracked here, using these accessory muscles improperly can result in a whole host of musculoskeletal complaints. A more detailed discussion of breathing will be saved for another day.
Overuse generally follows some form of disuse. For instance, the "weekend warrior" may run too far too soon while preparing to run his or her first road race. On the other hand, someone may simply ask too much of a given muscle group in a work (overtime), or sport based (extended weekend tournament) scenario. Of course these scenarios are not all encompassing, but they do provide some insight as to what may or may not aggravate a new or pre-existing complaint.
Abuse is some form of trauma to the body that is in many (but not all) cases difficult to prepare for. For instance, being on the receiving end of a check from behind while playing hockey, or catching a rut at the most inconvenient time of your ski run are both unfortunate and unpredictable scenarios. But the outcome of these scenarios largely depend on the body's prior conditioning and willingness to adapt to the situation (through proprioception, neural recruitment of different muscle groups, resilience of the body tissues, etc).
One thing that these four scenarios have in common (and could be argued to some degree for the "abuse" scenario) is that the body does not go from being A-OK to being in loads of pain. There is a middle ground that can be anywhere from a few milliseconds (some forms of trauma/"abuse") to decades (all four scenarios).
Part 2 and 3 of this discussion will cover various strategies to reduce the likelihood of experiencing various forms of dysfunction - therefore reducing the likelihood of experiencing a painful complaint.