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Muscle Building

Muscle Building


This lesson will describe the effects that exercise has on your muscles.

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In this lesson today we will talk about muscle building and how aerobic exercise and strength training can have an effect on muscles. So aerobic exercise and strength training both do have an effect on muscles, but the effects that they have are different.

So let's start by talking about the effects that aerobic exercise can have on muscles. When we talk about aerobic exercise, we're talking about exercises such as running, swimming, jogging, biking. These are exercises that increase your heart rate.

So when you are doing aerobic exercise, the effect that it has on your muscles is that it will actually increase the quantity and the size of mitochondria in muscle cells. And if you will remember, if you know about the structure of a cell, the mitochondria is the powerhouse of the cell. And the function of the mitochondria is to produce ATP energy for the cell.

So by increasing the size and the quantity of mitochondria, muscles are able to produce more energy and therefore can sustain the aerobic activity for a long period of time. A person who does a lot of aerobic exercise will also have more capillaries running to the muscles.

And by having more capillaries running to the muscles, it means that you have more blood going to those muscles providing more oxygen. And you also will have a more myoglobin. The levels of myoglobin will then increase as well. And myoglobin is a protein that binds to oxygen.

So you're having an increase in blood flow and an increase in oxygen to those muscles, providing more oxygen and then also able to remove carbon dioxide at a faster rate as well. And muscles over time from aerobic exercise will be able to work longer without tiring.

So if you start, for example, let's say you don't run or jog very often. And you started running or jogging today, and maybe you did so three or four times a week. Over time, your muscles would be able to adapt to that exercise. Your mitochondria would increase.

More capillaries would run to those muscles in your legs. And you would be able to run for a longer period of time without tiring out. So that's the effects of aerobic exercise on a muscle.

Strength training can have effects on muscles as well. So strength training would be something like weightlifting. So when you're doing this, you're lifting weights, and you're increasing the force that your muscles can exert. So this is affecting your fast muscle fibers. And if you'll remember, you have fast muscle fibers and slow muscle fibers.

So fast muscle fibers are being affected in strength training. More myofibrils are being produced. Therefore muscles are increasing in size and also becoming stronger. And muscles that go through a lot of strength training can be very strong, but they don't have much endurance.

So they can't sustain the activity for a very long period of time. And creatine is a substance that's naturally found in muscles. It works to replace ATP while the muscles are working out. So oftentimes people who do a lot of strength training will take creatine as a supplement.

And therefore ATP can be produced in their muscles more quickly. So that way, they can sustain this activity for a longer period of time. So a lot of athletes, it can be common for them to take creatine as a substance because they can then produce more ATP at a faster rate to sustain their activity for a longer amount of time.

So strength training and aerobic exercise both have effects on muscles, but their effects that they have are different. So if you want to have the best workout possible, the best thing that you can do is really to combine strength training and aerobics so muscles really get the best of both worlds.

So this lesson has been an overview on the effects of aerobic exercise and strength training on muscles.

Terms to Know
Aerobic Exercise

A type of physical activity that gradually conditions slow muscles to work for longer periods of time.


A substance found naturally in muscles or used as a supplement to replenish ATP during muscle workouts allowing muscles to sustain activity for longer periods of time.


A pigment that binds oxygen for the use of ATP production.

Strength Training

A type of physical activity that increases the size of the muscles and has an affect mainly on fast muscle fibers.