Smoking and Exercise

 Cardiovascular Effects of Smoking:

Aerobic exercise challenges the body's ability to supply and handle oxygen. For example, when performing high-intensity aerobic exercise, mitochondrial reactive oxygen species' (ROS) grow in number. ROS, is left unchecked, have have the ability to cause genetic mutations. However, several enzymes -- including superoxide dismutase -- are present to handle this oxidatve stress caused by ROS.The body responds to chronic aerobic exercise by enhancing its ability to cope with ROS.

Smoking also induces an oxidative stress; however, smoking-induced oxidative stress also inhibits the body's abiltiy to cope by suppressing the genes responsible for antioxidant production.  The net result of smoking-induced oxidative stress is vascular and arteriolar inflammation -- further impairing the oxygen-delivering capabilties of the body. Clearly, by limiting oxygen delivery, cigarette smoking impairs the ability to generate energy through the oxidative energy system. However, literature also suggests that smoking impairs anaerobic energy provision by altering contractile proteins, creatine kinase, and other glycolytic enzymes. With this in mind, therapists should be weary of setting unrealistic goals for patients who are smokers.

Smoking is a huge risk factor coronary artery disease and many other complications such as myocardial infarction and sudden death. Smoking is one of the biggest cause of death in the world. Smoking is also associated with marked, acute, and increase in blood pressure, systemic vascular resistance, and heart rate.  Nicotine is one factor that stimulates epinephrine and norepinephrine release from the sympathetic nerve terminals and adrenal glands, which explains that acute cardiovascular effects may be due to adrenergic stimulation at the peripheral levels. Acute cigarette smoking is associated with a significant decrease in vagal cardiac modulations which may increase the risk of complications during daily exercise or intense physical activity. Acute smoking affects the cardiorespiratory responses to both submaximal and maximal exercise, which can result in an increase of sympathetic dominance at lower levels of submaimal work.  Clinicians should be considerate of all options and treatment plans for patients who are avid smokers.

Smoking has not only been shown to be associated with an increase in resting heart rate (HR), but also with a significantly diminished increase in HR during exercise (known as chronotropic incompetence).  Chronotropic incompetence (CI) prevents the heart from being able to keep up with increased demand during activity and therefore reach the age-appropriate maximal HR.  Since an increase in HR is key to performing exercise for any significant amount of time, CI leads to progressive deterioration in exercise tolerance.  As CI worsens through habitual smoking over time, it can move beyond exercise tolerance to affect basic functional activities of daily living. CI caused by smoking has traditionally been observed in middle-aged and older adults, however a more recent study of male and female young adults (20-29 yrs) found that smokers had a significantly lower maximal HR and a significantly slower HR increase during exercise testing when compared to non-smokers.

Musculoskeletal Effects of Smoking:

Smoking has also been found to have a negative effect on bone mineral density which is directly related to osteporotic fracture.  Smokers do not absorb supplemental or dietary calcium as well as non-smokers. Studies show that smokers on average have 20mg/day less available calcium than non-smokers. The full reason in which calcium absorption is decreased is still unclear, but one explanation is that smoking damages intestinal villi which is a major component in digestion and absorption of nutrients.  The decreased ability to absorb calcium is directly realted to bone mineral density. Decreased bone mineral density effects the ability to exercise because increased risk of osteoportoic fractures.

The use of cigarettes and other tobacco products has also been found to be a contributing factor to age-related muscle atrophy, which is known as sarcopenia. Studies have found that when compared to non-smokers of similar backgrounds those who did smoke had evidence of increased muscle tissue deterioriation.Some research has also found that the use of these products can cause excessive amounts of adipose tissue catabolism during and after exercise. This can also lead to muscle tissue wasting in those who are nutritionally deficient. Researchers believe that this is a cause for a condition known as cachexia, a syndrome in which the patient loses muscle mass uncharacteristic to aging. This metabolic condition is usually seen in patients with cancer or other issues such as congestive heart failure.

Smoking is an overall unhealthy habit and causes many of the physiological effects described above that can hinder exercise performance, but it can also decrease the amount a person exercises. In a study done by Loprinzi and Walker, the variables of nicotine dependence and the amount of exercise per day were compared. They further split up the participants to account for other variables including age, gender, race, and several others. Through data analyses this study found that there was a positive correlation between higher levels of nicotine dependence and sedentary behavior in participants 50 years of age or older. The study also found that older participants were more dependent on nicotine. This information shows us that individuals who smoke may exercise less and may need to be encouraged to participate in a more active lifestyle.

Alternative Sources of Nicotine and Their Effects on Exercise:

While smoking can create adverse health issues for individuals, an athlete may be prone to the use of smokeless forms of nicotine to help with exercise performance. Through smokeless forms of nicotine use an individual may be able to obtain a greater concentration of nicotine, while being able to avoid the inhalation of harmful smoke. It has been shown that nicotine has the ability to increase blood flow in muscles, as well as increase the breakdown of lipids during exercise. This is due to "enhanced circulating levels of norepinephrine and epinephrine as well as direct action on nicotinic cholinergic receptors in adipose tissue". In addition, studies have shown that nicotine use can improve cognitive function, such as "learning and memory, reaction time, and fine motor abilities". Nicotine has also been found to aid in pain tolerance, which athletes could find beneficial if they participate in contact sports. While nicotine has been shown to provide an ergogenic effect on exercise performance, nicotine is still a highly addictive drug which can result in withdrawal symptoms effecting motor skills for individuals that abstain from nicotine for a short period of time.

Individuals seeking nicotine without the added chemicals found in tobacco may turn to electronic cigarettes (ECIGS). ECIGS are becoming a popular alternative to traditional tobacco cigarettes since 2007. While most research regarding the long-term effects of ECIGS is still in infancy, several studies address ECIGS as a viable step in smoking cessation and note the reduction in negative health effects. A longitudinal study conducted over the duration of a year by Etter (2014) reported on two groups, those who just use ECIGS (vape) and those who vape and smoke traditional cigarettes. Use among the vape only group did not increase over time, while almost half of the dual users were able to quit smoking traditional cigarettes. While ECIGS may be a safer alternative to traditional cigarettes, it is important to note the specific differences and similarities between the two as they relate to exercise. A study by Yan (2015) investigated nicotine intake and the acute effects of ECIGS on heart rate and blood pressure, in direct comparison to traditional tobacco use. They found that participants using ECIGS had significantly lower blood plasma levels after 30 minutes of controlled use, followed by one hour of free use. The ECIG users showed consistent levels of exhaled CO levels, heart rate, and blood pressure versus the magnified levels displayed by smokers. These findings suggest ECIG users do not need to receive the same precautions as traditional smokers in regards to exercise prescription.

Exercise has been shown to reduce cravings to smoke. Roberts et al. (2015) found that vigorous exercise can drastically reduce the cravings for nicotine. The researchers believe this is due to the realease of noradrenaline and cortisol. However, it is important to note that light to moderate exercise does not appear to reduce cravings for nicotine.  While exercise does not completely get rid of the desire to smoke, it can be healthy and more affordable alternative to the use of other products that also help people quit smoking. A therapist should encourage patients to adopt an exercise regimen if they mention that they are trying to quit smoking. Additionally, a therapist should be able to provide the patient with an exercise plan if they request one.