Hormones serve as important chemical messengers in the body that instruct our cells, organs, and other important tissues what to do.
Here is just a smattering of the various roles that hormones play in the body:
- Energy metabolism
- Tissue growth
- Reproductive processes
- Hydration levels
- Protein synthesis (muscle building)
- Protein breakdown
- Mood
- Decision making
- Fat burning
As you can see, hormones are incredibly important. Not only are they affected by our diet and exercise program, but the flip side is also true -- our hormones can affect our training.
In this article, we’ll discuss how hormones can affect women’s and men’s training.
How Hormones Can Affect Training
Dopamine
Dopamine is a neurotransmitter heavily involved in mood, motivation, focus, and the feeling of reward -- hence its name as the “happy hormone.”
While much of the focus on dopamine has centered around its neurological functions, dopamine also serves as an important signaling molecule in peripheral tissues as well, including the kidneys, pancreas, lungs, and blood vessels.[1]
For example, renal dopamine has been recognized as an important regulator of sodium extraction and electrolyte balance. As you likely now, electrolytes play a vital role in hydration as well as the contraction and relaxation of muscle tissue.
Based on this, not only could low dopamine decrease your desire to work out, it may actually impact hydration levels, which has a direct effect on your ability to perform and resist fatigue.
Glucagon
Glucagon is considered one of the primary catabolic (protein breakdown) hormones in the body. It is produced in the pancreas and works to increase levels of glucose and fatty acids in the bloodstream.[2]
Glucagon is released when the hypothalamus (a region of the brain tasked with releasing hormones and regulating body temperature) senses hypoglycemia (low blood sugar).
The hypothalamus then sends a relay signal to the pancreas to release glucagon, which subsequently stimulates the release of free fatty acids (FFAs) from adipose tissue (fat cells) and increases blood glucose levels by tapping into glycogen stores in the liver.
High intensity exercise is heavily reliant upon glycogen (stored glucose) for energy. When blood glucose or muscle glycogen is low, glucagon helps cultivate additional glucose (from liver stores) to fuel exercise.
If glucagon is not functioning properly or if liver glycogen stores are low (such as when training after a long fast), exercise performance could be severely impaired.
Testosterone
Testosterone is regarded as the “king” of anabolic hormones due to its role in helping individuals build muscle.
Both women and men have testosterone, but men have substantially larger concentrations of the anabolic hormone than women.
However, this doesn’t mean that women have any harder time building muscle than men.
While testosterone does play a role in building muscle, recent studies suggest that an individual’s androgen receptor density may play a larger role in building muscle than the amount of testosterone they have.[3]
Still, testosterone does serve other roles besides anabolism. It also impact a person’s energy levels, cognitive function and motivation.
By that we mean that low testosterone levels (in either men or women) could impair performance or an individual’s desire to train at al.
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Progesterone
Progesterone is a steroid hormone secreted by the corpus luteum during the second half of the menstrual cycle.
Higher progesterone levels have been linked to increased body set-point temperature as well as increased breathing rates. [4]
The downside of this higher core temperature and breathing is that your workouts may “feel” harder and it may also take longer before the body starts to cool itself, on account of the higher body temperature.
Now, it’s worth mentioning that VO2 max and lactate threshold largely remain steady throughout a woman’s monthly hormonal cycle, meaning that exercise might “feel” harder, but your actual performance may not be hurt by the alteration in progesterone.
Cortisol
Known as the “stress” hormone, cortisol is a catabolic hormone secreted by the adrenal glands in response to stress, low blood sugar or exercise.
It serves an important role in energy metabolism during prolonged periods of fasting as well as long bouts of exercise as it catalyzes the breakdown of triglyceride (the primary constituent of fat) and protein to produce the glucose needed to fuel exercise.
Cortisol is produced when we experience too much physical, emotional, or psychological stress or if we’re not sleeping well.
While acute spikes in cortisol can help enhance fat burning during a workout, exercising for too long (particularly in a fasted state) or dealing with constant life stress can lead to chronically elevated cortisol levels, which promote muscle breakdown and fat storage.[5]
Insulin
Insulin is an anti-catabolic hormone released by the pancreas that regulates carbohydrate and fat metabolism.
When you are in a fasted state (or following a very low-carb diet, such as a ketogenic diet), insulin levels are low, which causes the body to rely primarily on stored body fat for fuel.
When you eat carbohydrate- and/ or protein-rich meals, insulin levels due to the influx of glucose and amino acids into the bloodstream. Insulin’s job is to help maintain steady blood sugar levels, as having too high of a blood glucose concentration can be toxic.
To keep blood sugar within a safe range, insulin picks up glucose and amino acids from the bloodstream and shuttles them into your cells, where they can be used for energy production, glycogen replenishment, and tissue repair.
Furthermore, when you start exercising, the sympathetic nervous system (the one that controls the “fight or flight” response) suppresses insulin release and stimulates cortisol secretion as the body perceives a stressor, and it enacts the “get into action” protocol.
Lastly, since insulin is responsible for shuttling nutrients into cells and temporarily suspending fat burning, it’s often (incorrectly) promoted by low-carb advocates that insulin is to blame for people getting fat or having trouble losing weight.
The reality is that if you are in a calorie deficit, you can lose weight, regardless if you follow a high, low, or no-carb diet. Insulin (and by proxy, carbohydrate) is not the enemy of dieters, it’s the excess consumption of calories.
Insulin helps deliver the glucose that’s needed to power high intensity muscle contractions, and it also helps prevent the breakdown of muscle tissue by suppressing cortisol -- a catabolic hormone.
Estrogen
Estrogen is the primary female sex hormone, but it is also found (in limited concentrations) in men.
Research has found that estrogen directly affects the structure and function of muscles, tendons, and ligaments in that it improves muscle mass and strength. It’s also been found to increase the collagen content of connective tissues.
However, estrogen has also been found to decreases stiffness in tendons and ligaments, which directly affects performance as well the likelihood of injury.
This leaves us at a crossroads.
Fortunately, a recent 2019 meta-analysis investigated the body of research analyzing the effects of estrogen on exercise performance and injury risk concluded:
“These studies make it clear that estrogen improves muscle proteostasis and increases sinew collagen content; however, the benefits on bone, and muscle come at the cost of decreased connective tissue stiffness. Evolutionarily, this makes sense since laxer joints and better repair following injury would facilitate healthy childbirth and recovery. However, as more women participate in sports it is clear that these physiological effects of estrogen contribute to decreases in power and performance and make women more prone for catastrophic ligament injury. In order to promote female participation in an active lifestyle throughout their life span, more research is needed to determine how nutrition, training, and hormonal manipulation can be used to promote optimal performance at any age.”[6]
Basically, estrogen may enhance protein synthesis (muscle building) and collagen content, but it also reduces connective tissue stiffness, which could increase the likelihood of injury. Still, with the increasing amount of females that are participating in strenuous sports, more research is needed to elucidate just how much an individual’s estrogen levels affect their performance or risk of injury.
Adrenaline & Noradrenaline
Adrenaline (epinephrine) and noradrenaline (norepinephrine) are downstream catecholamines/hormones of dopamine.
As you’re likely aware, these chemicals play a prominent role in the “fight or flight” response of the body and help increase alertness, concentration, and motivation.
More specifically, adrenaline increases cardiac output (how much blood your heart is pumping), increases blood sugar (to provide fuel for your muscles exercise), and catalyzes the breakdown of glycogen and fat for energy.[7]
Noradrenaline performs several of the same functions as epinephrine, but it also acts as a vasoconstrictor (narrows blood vessels) in regions of the body not heavily involved in exercise.
Adrenaline and noradrenaline also play a prominent role in your body’s ability to burn fat for fuel. These chemicals can bind to the beta receptors on adipocytes (fat cells), which essentially “unlocks” the fat cells, causing them to dump fatty acids into the bloodstream.
From here, L-Carnitine can pick up the fatty acids and shuttle them into the mitochondria where they can be oxidized (“burned”) to generate ATP and power the body during low-intensity activity -- walking, light jogging, steady-state cardio, etc.
Takeaway
Hormones are important chemical messengers that control numerous biological processes and they may also impact our ability to perform and recover from training.
However, it’s worth noting that hormone levels can vary drastically between individuals.
Furthermore, there is a distinct lack of research investigating the effects hormones have on exercise. A considerable amount of research has been conducted investigating how different exercise modalities affect hormones, but very little work has actually been done regarding how hormones affect training.
References
- Drozak, J., & Bryla, J. (2005). [Dopamine: not just a neurotransmitter]. Postepy higieny i medycyny doswiadczalnej (Online), 59, 405–420.
- Scott RV, Bloom SR. Problem or solution: The strange story of glucagon. Peptides. 2018;100:36–41. doi:10.1016/j.peptides.2017.11.013
- Morton RW, Sato K, Gallaugher MPB, et al. Muscle Androgen Receptor Content but Not Systemic Hormones Is Associated With Resistance Training-Induced Skeletal Muscle Hypertrophy in Healthy, Young Men. Front Physiol. 2018;9:1373. Published 2018 Oct 9. doi:10.3389/fphys.2018.01373
- Saaresranta, T., & Polo, O. (2002). Hormones and breathing. Chest, 122(6), 2165–2182. https://doi.org/10.1378/chest.122.6.2165
- Epel, E. S., McEwen, B., Seeman, T., Matthews, K., Castellazzo, G., Brownell, K. D., Ickovics, J. R. (2000). Stress and body shape: stress-induced cortisol secretion is consistently greater among women with central fat. Psychosomatic Medicine, 62(5), 623–632.
- Chidi-Ogbolu, N., & Baar, K. (2019). Effect of Estrogen on Musculoskeletal Performance and Injury Risk . Frontiers in Physiology. https://www.frontiersin.org/article/10.3389/fphys.2018.01834
- Zouhal, H., Jacob, C., Delamarche, P., & Gratas-Delamarche, A. (2008). Catecholamines and the effects of exercise, training and gender. Sports Medicine (Auckland, N.Z.), 38(5), 401–423.https://doi.org/10.2165/00007256-200838050-00004
