Hormones- The Masters of the Machine

Hormones... these little buggers can get very complicated very quickly. They have their fingers in everything and they can act differently on different cells or at different concentrations. BUT, they can be understood if you focus on what a hormone is trying to accomplish (and if you ignore everything not related to swimming). Instead of trying to understand all the effects of each hormone on a thousand different cell types, it is easier to understand what a hormone is trying to get the body to accomplish. Figure out what the target is, and the road to that target becomes clear.

A hormone is a signal. A molecule secreted by various glands and tissues which tell other tissues what to do. They are like coded messages that get sent out from HQ. Each cell target, however, has a different “key” to the code and will get a different message after they decode the hormone. This means one hormone can have a different effect on different cell types: muscle, nerve, blood vessel, brain and a hundred more.

The one nice thing about hormones is that they help put the entire picture together. They bring together all the other topics we talked about and make them work together as one unified swimming machine. To help understand what a swimmer needs to know about hormones, we are going to start a work out and see what happens.

Training hormones: keeping up sugars and pressures

Practice starts and muscles start working. If you remember, muscles use sugar and fat as fuel. They get those from two places: what is stored inside the muscle cell itself, and from the blood. Blood then gets sugar from the liver and fat from fat cells.

Since the blood only has about 100 calories of sugar in all of the blood at any one time, it drops fast when workout starts. For instance swimming fly can burn up to 1000 calories a minute… the body wouldn’t last 12 seconds. And while muscle can rely on fat as a fuel, the brain really really really likes sugar, and so many hormones exist to keep the bloods sugar levels from dropping. Right now, that’s the body’s target: Keep sugars up!

We will get to insulin later, but out of all these hormones that raise blood sugar glucagon and epinephrine are the most important during exercise. Before your swim workout can drop sugar levels, these two hormones kick in to keep the sugars up. Another important reason for warm-up!

Glucagon works mostly on the liver. The liver can store 5% of its weight as sugar, but even that is not enough to keep blood sugar levels high after a while. So, glucagon causes the liver to run glycolysis in reverse (haven’t talked about glycolysis in a while, if you forgot what it is, you can find it in the Energy Systems). This process will take protein and make sugar out of it and it is called gluconeogenesis. Now that’s a scrabble word, but if you break it down it makes total sense.

While this works well, it is really only enough to keep your brain happy (about 500 calories a day) and your body would rather not use up all its precious muscle mass to keep sugar levels up. That’s where epinephrine comes in. Epinephrine is the same as adrenaline, and is part of a group of hormones (called catecholamines) designed to keep you alive right now, in this moment. That’s their target. While they simultaneously make a lot of changes in the body, when it comes to keeping sugar levels up, epinephrine does two things: it increases muscles’ use of its own stored sugars, and it increases the body’s release of fat so muscles can use it better and “spare” sugar.

Tangent: Epinephrine is called the “fight or flight” hormone, it gets everything ready to go by increasing the sympathetic nervous system (because it is “sympathetic” to your survival).

The way your body stores and releases fat is a little complicated and we will talk about it more in the nutrition article, for now this is what you need to know. All over your body are fat storing cells called “adipose cells.” They are literally just giant blobs of fat. But they store this fat as a triglyceride which is a huge molecule and can’t be released into the blood. Epinephrine acts on one enzyme (Hormone Sensitive Lipase if you were curious) that cuts the giant triglyceride into Free Fatty Acids. These guys can float in the blood and are used by muscle and other organs.

We also said epinephrine increases muscle’s use of sugar that is stored in the cell itself. This is NOT to release it in the blood. Muscle cells CANNOT remake sugar from protein (gluconeogenesis) and they cannot release any sugar into the blood. Epinephrine’s only job is to get you ready for a fight, which means giving the muscle the maximum fuel available.

Tangent: Fast twitch fibers can do gluconeogenesis if lactate levels are very very high and only during acute recovery (like in between 100s all out on 6 min). But this is probably such a small amount we can ignore it.

While this helps the muscle produce a lot of power by burning sugar, remember that acid is created in the process, and this needs to be shunted away and out of the cell (read up in Lactate Threshold). This is where epinephrine’s other job comes in. You don’t need your stomach, skin or kidneys to survive a fight (and yes, that’s what your body thinks is happening during workout and races… a fight). So your body needs to redirect all that blood from those “useless” organs and give it to the muscles that really need it. We learned about this in the Cardio article, but now let’s take a closer look. By constricting the blood vessels in skin and other organs while simultaneously dilating vessels in muscles, the body can more efficiently use the blood it has. This also explains why people look pale when they get scared, the blood vessels in their skin clamp shut so there is less “red” in their face. This is all controlled by epinephrine, it simultaneously causes blood vessels to muscles to dilate, increasing blood flow, which also constricting blood vessels to other organs you don’t need, limiting their blood supply.

To further improve cardio, epinephrine has a direct effect on the heart and increases its rate and squeezing ability. This is why hard workouts feel hard. But with training, all of what we have talked about improves. Muscles use fat better, blood volume goes up and your heart grows in size. That means the rise in both epinephrine and glucagon after getting in shape is not as much as in the beginning of the season. And when you are just sitting on the couch reading this article, your heart rate slows way down as a “rebound reaction” to not having all that epinephrine around. This is why athletes have much lower resting heart rates than normal people.

During an all-out race however, there is no decrease in epinephrine release. It all gets dumped into the blood no matter how good a shape you are in. And because it does have a small effect on the liver, you can actually have higher than normal sugars in your blood as you get jacked up for your race. This is why coach keeps giving you speeches about “mentally” preparing before a race… because it’s not just mental.

Cortisol is another hormone that gets released during exercise. Cortisol is a “stress hormone” and its goal is to keep your body on its toes and alive for the long haul. Like glucagon and epinephrine, cortisol plays a big part in maintaining blood sugar and will cause a rise in blood sugar all by itself. Cortisol will also try to spare the use of sugar by increases fat and protein use. Unfortunately, it gets that protein from muscle. That’s ok in small amounts during workout, but if cortisol goes out of control… like during over training, then you can have a bigger problem on your hand. We will talk more about overtraining in another show.

As you can see, cortisol has its fingers in everything. In very high levels (like when we doctors give patients pills of this stuff), cortisol will suppress the immune system, cause Diabetes, weaken your bones, thin your skin and cause your arms and legs to atrophy (loose its muscle mass) as it moves the extra energy from muscle to fat. But don’t worry… no amount of overtraining (with a decent diet) will cause all of this to happen to you. This is just an example of how strong these hormones can be.

Workout keeps going on and you become more and more dehydrated and low on sugar stores. Epinephrine, glucagon and cortisol respond by slowly rising throughout workout in the hopes of maintaining both blood sugar and proper blood flow. So the set that started pretty easy, now feels like swimming with a piano on your back. Lucky for your, workout is over and it’s time to recover!

Recovery hormones: refuel, rebuild, rehydrate

Think about how you feel right after workout is finished… I bet you have three big complaints: your thirsty, you’re hungry and your body hurts all over. That makes total sense! You just spent all the sugar in your muscles and liver, you sweated out all the water in your blood, and you broke a lot of muscle cells when coach made you do those 100 flys all-out. All of that needs to be fixed and hormones pull the strings on all of them. Let’s take these three “targets” one by one and see how your body gets ready for the next workout.

Let’s start with sugar. During workout your muscles were burning the sugar inside them, and hormones like glucagon and epinephrine were releasing sugar from the liver to feed the muscles too. Now it is time to reverse all that with one big hormone called insulin. When you eat carbohydrate loaded food your body absorbs the sugar and dumps it into the blood. BUT… muscles are not allowed to just take that sugar from the blood without permission, because the brain gets first dibs and it does not need insulin to give it permission to take sugar. Insulin acts as permission for the muscles to start taking the sugar from the blood and storing it up inside the muscle cells. Insulin will also push sugar into the fat cells in order to convert sugar into fat and store it up for later.

Certain proteins will also cause a rise in insulin. That’s because protein is one way the body can create its own sugar. We talked about this before (gluconeogenesis in the liver), but we mention it again because it turns out that protein is very important to refueling sugar stores in the muscles. High protein diets aren’t just for bodybuilders, some even say endurance athletes need a diet with higher protein amounts than even weightlifters!

Tangent: During workout and right afterward you actually don’t need insulin to get sugar into muscle. This is VERY IMPORTANT when we talk about nutrition, timing certain meals and body weight control.

Now that we are refueled, let’s rehydrate. As we talked about in the Cardio article, having a high blood volume can make the heart work more efficiently and send blood to more parts of the body like muscles and skin (for cooling). One of the things in your blood is sodium (basically salt) which becomes more concentrated as you lose water through sweat (no… you don’t lose that much salt in your sweat). Your brain can measure this hyper-saltiness in your blood and starts secreting a hormone called Anti-Diuretic Hormone, also called vasopressin. Both names tell us what this hormone does.

Tangent: This hormone is blocked by caffeine and alcohol, which is why you have to pee so much after a cup of coffee.

This is the hormone responsible for that “thirsty” feeling to try to get you drink water and re-dilute the salty blood. It also causes less water to be filtered and peed out by the kidneys. It also causes blood vessels to constrict in order to keep blood pressure high when there isn’t enough blood to fill up the pipes. Another thing that happens during workout is that blood is shunted away from the kidneys. The kidneys don’t like that, so they start dropping a hormone called aldosterone. This is also responsible for keeping your blood volume up by making your blood more salty by preventing the kidneys from peeing it out. That way, water is retained and pee is concentrated. I know… I just said two seconds ago your body doesn’t like salty blood, but salt holds on to water so aldosterone works in the kidneys to prevent salt from being peed out, and if the body has to choose, it would rather be salty than dry. That’s the same reason for why pure water isn’t a great re-hydrating fluid. Because it has no sodium in it, only about 70% of what you drink gets absorbed no matter how dehydrated you are. Chicken broth or soup has been shown to re-hydrate way better, closer to 95%. So the next time you swim the mile in the first session, consider a big glass of broth to jump start getting your blood volume back!

Tangent: You might think sports drinks are good at rehydrating, but they don’t have enough salt in them. They do have a lot of sugar, which is still good to help keep blood sugars up.

Both aldosterone and anti-diuretic hormone control blood volume. Over the first week of the season, they can increase blood volume by 400 milliliters, or by about 10%. That’s a big deal when we are talking about improving your swimming machine by seconds per 100. These hormones are secreted based on intensity of workout. The harder workout is, the more hormone you have running around and the more blood volume you will maintain. So don’t complain so much when coach writes up 8x400s with a 200 all-out at the end, it’s good for you.

Tangent: Before your race, epinephrine thinks you are about to get cut up and lose blood in a fight, so it tries to conserve water where it can. That’s why your mouth gets so dry before a race. But your body is smart, it knows it needs to stay cool no matter what, so sweat glands actually don’t listen to epinephrine at all. Different system.

With all this extra water on board, the blood becomes “dilute” of red blood cells. If severe, you can be diagnosed with Athlete’s Anemia (which is normal). The kidneys see this too and start releasing a hormone called erythropoietin, or EPO. Kidneys will pump out EPO if the oxygen content in your blood drops, like when you are at altitude (another show).

This hormone you may have heard about since it used to be used a lot for doping. Its job is to signal the bone marrow to increase red blood cell production to fill up the blood again. EPO can also be released during hard workouts, another reason for those sprints at the end of practice.

Tangent: Too much red blood cells in your blood will cause it to be too thick, preventing the heart from pumping it. This has the unfortunate result of death, which is why doping with EPO not common anymore!

And the last target on our list is rebuilding what we broke, that includes muscle cells, connective tissue, blood vessels and enzymes. These all require proteins to be built from scratch, called an “anabolic process.” This is where we get our word for anabolic steroids, as in “something that builds.” Many hormones have an anabolic effect like insulin and testosterone with the most powerful being growth hormone.

Tangent: Stomach grumbling at all? That’s a hormone called ghrelin which is secreted by your stomach when you’re hungry. It gives you that “hungry” feeling.

Growth hormone is one of those buggers that has its fingers in everything. If you’re young, it is responsible for making you taller, among other things. If you are old and your growth plates have closed, tumors secreting too much growth hormone will cause bones to grow wider, a condition called acromegaly (in case you were wondering). But the big thing to know about growth hormone is that it is a strong signal to build muscle, and lean out fat. It increases protein synthesis for all processes in the body. Growth hormone is NOT intensity specific, which means if you work out in any capacity for longer than 15 minutes, you will get a boost in this hormone. That gives a good reason for short, easy work outs during the week to help boost recovery.

Tangent: Oldies use growth hormone (illegally) as an “anti-aging” drug.

The last anabolic hormone to talk about is testosterone. I am unaware of any specific workout or diet that will increase testosterone levels in men or women, but we can talk about it a little. Obviously, men make more testosterone than women, and it probably accounts for the extra 30% muscle mass you see in men. But, here is the deal… men have 100s of times more testosterone than women, and to add any muscle requires 10 times the amount men have running around normally. That means if you want testosterone to be a big factor in your training, you either need to dope or have an extra pair of nuts (whether you’re a guy or girl).  

Tangent: Progesterone is another “steroid” hormone that is more abundant in women. It is boosted during pregnancy and can loosen tendons providing extra flexibility. This might be a reason girls are more flexible than boys, especially if they are pregnant.