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.

METH use can have harmful effects on the pulmonary system. Research has found there to be an association between stimulants like METH and acute pulmonary edema. This can lead to acute cardiogenic pulmonary edema, which can cause other complications such as fatigue and even failure of the respiratory system to function. METH is also associated with pulmonary hemorrhaging. Understanding how the pulmonary system is effected with heavy or frequent METH use is crucial in implementing an exercise plan that will not put too much stress on the pulmonary system.

Chronic METH usage has many effects on the cardiovascular system. Wijetunga, Seto, Lindsay, and Schatz (2003) found that METH use is associated with chronic heart failure and cardiomyopathy. Cardiomyopathy causes the heart muscle to become thick and rigid, which makes it harder for the heart to pump blood through the body. Additionally, these researches found that METH usage can cause structural changes in the heart, like ventricular remodeling. Cardiomyopathy and ventricular remodeling makes the heart less efficient at pumping blood and at oxygenating the tissues. Patients with cardiomyopathy due to METH use are likely to become short of breath quickly. Therefore, these patients should be given a light to moderate intensity exercise plan and be able to take breaks frequently.  An article that further discusses the adverse effects of meth use on the cardiovascular system is: The article was: Kaye, S., Mcketin, R., Duflou, J., & Darke, S. 2007. Methamphetamine and cardiovascular pathology: A review of the evidence. Addiction. (102)8. p. 1204-1211. This article states that some of the acute cardiovascular effects that go along with meth use are tachycardia, palpitations, and chest pain. There are some more serious side effects that are related to chronic meth use. These side effects are chronic hypertension, myocardial infarction, aortic dissection, and sudden cardiac death. Patients that are suspected to be meth users need to be monitored during physical activity as some of these severe side effects can result in death.

The use of methamphetamines can also have a negative effect on bone health. Tomita, Katsuyama, Watanabe, Okuyama, Fushimi, Ishikawa, Nata, & Miyamoto (2014) contucted a study on mice and the effect of METH on their bone health. There was one control group, and two groups that each received a different dose of methamphetamines. Each of the groups received their injections for eight weeks, and the bones of the mice were observed after the received each injection. The researchers observed that there was a decrease in osteoclast activity while there was an increase in osteoblast activity, creating an unbalanced formation of the bone. There were also low rates of bone turnover observed which suggested the bones were low in Vitamin K. Low bone turnover could result in osteoporosis. These results are important when considering excerise after long bouts of METH use. an imbalace in bone formation and the risk of osteoporosis can put the user at risk during exercise. While exercise can be beneificial for bone formation, the individual should take precautions to ensure that they do not put too much stress on their bones at the start of exercise.

Acute exercise may be a way to help those addicted to methamphetamines. Chang, Y-K., Wang, D., & Zhou C. (2015) performed a study that looked at neuroelectric and behavioral measurements in 24 methamphetamine dependent subjects. The control group participated in an active reading session, while the experimental group used a stationary cycle for an acute, moderate-intensity exercise session. The authors found that the exercise group reported signficantly lower “MA cravings during aerobic exercise and following the cessation of exercise, with the lowest craving scores observed immediately after and 50 min following the exercise session."  Using acute exercise to lower methamphetamine cravings is a novel idea, and the mechanisms must be explore further. The idea possibly provides an alternative to pharmacological interventions, and would be healthy and safe. We, as future therapists, could have a chance to make a big difference in the lives of methamphetamine dependent individuals.

An article by Dolezal et. al (2014) reiterated that exercise can be a proactive way to combat MA addictions, as well as to prevent relapse in recovering MA substance abusers. In this case, individuals living in a rehabilitation center for substance abuse who participated in an eight week exercise program including aerobic exercise, and muscle strength and endurance saw improvement in both categories, as well as a decrease in body composition due to the training. In this case, there was a considerable change in both physiologic functioning, as well as cognitive functioning (including combating anxiety and depression, which is common in recovering substance abusers) . Knowing how exercise can positively influence a person's body as it trys to heal itself from addiction can be a major factor in our physical therapy practice and exercise prescription. 

With exercise heart rate variability (HRV) is increased, but with methamphetamine usage results in decreased HRV. HRV is the interval between heartbeats representing the ability of the autonomic nervous system (ANS) to change with stimuli. So decreased HRV represented ANS dysfunction. The researchers concluded that through the examination of HRV of previous methamphetamine users showed increased ANS function by decreased sympathetic outflow and improved vagal modulation.

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