I can help with this topic-- I am an OT and a BSN student. Muscle tone refers to the amount of resistance to stretch muscles have while at rest. Most of us, whether we're fitness trainers or couch potatoes have "normal" muscle tone, meaning our muscles are in a state of slight contraction and ready for immediate activation while they are at rest. People with normal muscle tone are also capable of sustaining a prolonged contraction, then relaxing easily (picture carrying a 10 lb box, then setting it down). Muscle tone is not the same as muscle strength.
The amount of muscle tone a person exhibits is regulated in their cerebellum. There are lots of disorders and diseases that have an impact on the cerebellar function, and thus on muscle tone, causing hypertonia or hypotonia. Hypertonia and hypotonia are abnormal. Because abnormal muscle tone affects the way a muscle responds to stretch outside of the person's conscious control, it is not possible to accurately do muscle strength testing on individuals with abnormal muscle tone.
Hypertonic muscles are hyper-reactive to stimulation, causing over-reactive contractions. They also sustain contractions longer than needed and have difficulty returning to relaxed resting levels because they tend to re-fire easily. Hypertonic muscle tone is associated with spasticity. In more severe cases, a person can be rigid, but this is still hypertonia. As a side note, hypertonic individuals usually have a high metabolism because of their state of constant muscle activation. Hypertonic children often have poor weight gain and slow growth.
Hypotonia is the opposite of hypertonia. Hypotonic muscles are more relaxed at rest than "normal". They are also slower to contract with stimulation and do not have the same ability to contract fully or sustain a contraction. Hypotonic individuals often appear "lazy", but really they work harder to achieve and sustain muscle contractions. Hypotonic muscles appear floppy at rest, and at their more severe level, can be flaccid. Hypotonic individuals usually have slow motility and may gain weight easily due to their slower metabolism.
Hypotonic individuals are at risk for joint injury due to lax ligaments and hypermobile joints. Hypertonic individuals are at risk for joint deformity/contracture due to lack of joint mobility. Basically, muscle tone presents along a spectrum from flaccid to rigid, with "normal" being in the middle.
You should also know that a person's tone is what it is. People are not hypertonic one day and hypotonic the next. Working out in a gym will not improve your muscle tone, since it does not change the cerebellum's regulation of muscle contraction at rest. Working out simply reduces the fat to muscle ratio to make your muscle appear more defined. Not the same thing, but often confused by smart people (even exercise experts and nursing text book authors
Nursing assessment of muscle tone involves inspection and palpation, using test items for musculoskeletal and neurological assessment. Go back and review your textbook and it will start to make sense, with your new understanding of tone. The funny thing is, I am giving a presentation on this topic to my class in a few days. I think it's an important topic for nurses and I don't understand why it's not taught in school.
Here's another side note on ROM (for marcma03, because of your reference to "active.") Active range of motion (AROM) refers to a person actively moving his joints through all their planes of movement without assistance. Passive range of motion (PROM) is when the caregiver performs these movements for the patient who is unable. Active assist range of motion (AAROM) is when (I bet you can guess
) the caregiver helps the patient move through full range, when the patient is unable to do the complete movement pattern independently. When a patient has only one side affected (CVA), they can use their unaffected side to provide their own active assist.
Hope this has cleared up some confusion. I wish there was a way to add this to the nursing topics covered in school!