Nicotine's Impact on Muscle Growth
The impact of nicotine on muscle growth in humans is negative. Mostly because it affects the ability to constrict blood vessels, and thus reduces the flow of nutrients to muscles. In addition to this, nicotine can increase cortical levels which leads to muscle breakdown. In case you want to grow muscle, it is best to avoid nicotine.
What Is Nicotine?
Nicotine is a volatile liquid alkaloid, which can be naturally found in the leaves and stems of Nicotiana tabacum and Nicotiana rustica plants [1].
Nicotine is the primary component of tobacco [1]. It is responsible for the addition to tobacco resulting from chronic use of tobacco products as well as the smell associated with tobacco [1].
It is a highly addictive substance acting behaviourally. This means that people who are addicted become dependent on using tobacco in certain instances like using tobacco (and thus nicotine) after meals or under stress [2]. As such, people crave the chemical but also the mental effects of nicotine [2].
In fact, nicotine has some benefits, however it also presents with side effects.
Nicotine is consumed by inhaling the smoke of tobacco cigarettes, however, it can be found in other forms like smoking pipes or cigars [2, 3, 4]. Further nicotine can be found in chewing gum, transdermal patches, nasal spray, or sublingual tablets. However, those are usually used to eliminate the nicotine addiction [1].
How Does A Muscle Grow?
Muscle growth, or hypertrophy, is a complex process involving multiple mechanisms. It is also dependent on biological factors like testosterone and growth hormone as well as the availability of amino acids and other nutrients [5].
Our muscles can undergo both increase and decrease in size during everyday life and they are dependent on their contractile activity [6].
The most rapid muscle growth phase occurs in the perinatal period where the expansion of muscle mass goes from 25% of lean mass at birth to 40-45% at maturity [7].
Muscle growth can occur in three ways:
- an increase in the muscle cell numbers
However, this is limited to the prenatal and postnatal period. So the growth can only occur by [8]:
- an increase in muscle fiber diameter
- an increase in fiber length
When a person does an extreme exercise like weightlifting, the muscle fibers undergo trauma. Hence the satellites on the outside of the muscle fibers become activated. They try to repair the damage and join together. As a result, this increases the muscle fiber length and supports muscle growth [9].
Further, to increase muscle growth and build muscle, one has to increase the rate of protein deposition, while minimizing the rate of protein breakdown.
Read about peptides and muscle growth.
Does Nicotine Affect Muscle Growth?
The evidence is inconsistent. Some studies suggest that nicotine has a positive impact on muscle growth and development of muscles, whereas others suggest the effect is rather negative.
One study found that nicotine promoted the differentiation of C2C12 myoblasts ( a type of muscle cell ) and also that it improved skeletal muscle regeneration in obese mice [10].
However, another study found that a chronic intake of tobacco (which consists of nicotine) of 100g a week resulted in a reduction of 2.9% in knee muscle strength in men and %% in women [11]. It has also been found that nicotine includes myotube atrophy, a condition characterized by the wasting away of muscle fibers [12].
Further, a study found that prenatal exposure to nicotine speeded up the maturation of developing nerves and muscles in rat offspring [13].
To conclude, the studies suggesting a positive effect of nicotine on muscle regeneration and development were all conducted on murine models, whereas the ones suggesting the negative effect were done on humans. Therefore it may seem like nicotine harms humans and high doses of nicotine or exposure to nicotine during critical periods of development is not recommended to sustain healthy muscle growth and development.