Methamphetamine and Exercise

Amphetamines are a group of drugs with mind-altering capabilites. Methamphetamines are the most potent of the amphetamine group of drugs. Methamphetamine falls under the classification of a stimulant. Typically, stimulants will increases and individuals sensations such as mental awareness while also increasing one's ability to respond to the environment. Users of stimulants may also find an increase in energy levels. The effects that users feel while on methamphetamine (METH) causes this drug to be highly addictive. The physiological effect of METH is achieved by increasing the quantitiy and release of stimulatory neurotransmitters dopamine, noradrenaline and serotonin and decreasing their synaptic breakdown.

A primary clinical consideration for methamphetamine is its use with other medications. Acute use of METH with other stimulants can overstimulate the sympathetic nervous system, potenitally resulting in cardiac arrythmia, seizures, cardiovascular collapse, and death. Therefore, physical therapists should take special consideration when prescribing exercise to patients who present with signs suggestive of use. Characteristic presentation of METH use includes restlessness, weight loss, heightened alertness, violent behavior, and pupillary dilation.

An acute response to METH use is hyperthermia.  Although the exact mechanism though which this is achieved is unknown, literature suggests that methamphetamine-induced hyperthermia results from heat generation as well as an inhibition in heat loss.  One study conducted in 2009 aimed to explore the effects of brain hyperthermia brought on by METH. The reaserachers of this study injected rodents with differing amounts of METH, and then proceeded to measure how dosages and enviromental factors impacted brain hyperthermia . METH, especially in large doses, influences the metabolic activity of the brain due to oxidative stress which is what occurs when the body is unable to rid itself of free radicals at a rate to maintain a homeostatic balance . Temperatures inside of the brain also increase due to "enhanced release of meluiple neuroactive substance, lipid peroxidation.... and numerous changes combined as oxidative stress" . Increases in the metabolic brain activation paried with internal head production by the brain cells seem to be the driving force behind brain hyperthermia . Ingesting METH at increased tempertures or during social gatherings when an individual is more likely to be active such as with exercise only exacerbates this increase in core body temperture. Even slight increases in cell tempertures can cause denaturation, which can then lead to impaired cell function or ultimately death of the cell.

Thus, combining therapeutic exercise when an individual is experiencing methamphetamine-induced hyperthermia could result in serious harm. The current practice for cooling methamphetamine-induced hyperthermia is placing the individual in a cool environment to try to bring that person back into a homeostatic balance.

Chronic METH use results in a range of physiologic disturbances. An adaptation with the greatest relevance to physical therapists is the presence of congestive heart failure in chronic users.  Impaired oxygen delivery to tissues would result in an inability to safely engage in treatment on the part of the patient. Moreover, attempting to engage in such an activtiy could result in cardiogenic shock. If the practitioner engages the patient in these activities without knowing about METH use, the outcome could be fatal. Another clinical implication is that chronic METH use can break down the blood-brain barrier (BBB) over time, and it has been shown that increased permeability in the BBB can lead to damage of myelin . Without myelin, the nervous system is unable to communicate effectively to different systems, including muscular, which could have an impact on exercise prescriptions and individual expectations.