What is Glycolysis?
Glycolysis is the breakdown of glucose into two molecules of pyruvate (a compound that can be used as energy). Glucose enters the cell through one of three pathways: glycogenolysis, lactate dehydrogenase or pyruvate carboxylase. These are called the glycolytic pathway because they break down glucose into its basic form, which can then be converted to ATP.
The second pathway is known as the anaerobic glycolytic pathway. This pathway breaks down glucose into carbon dioxide and water. There are two main types of enzymes involved in this process: the Krebs cycle and the electron transport chain. Both of these processes require oxygen to work properly, but only one requires oxygen for each step. The Krebs Cycle uses electrons from NADH to generate ADP, while the ETC utilizes electrons from FADH2 to produce ATP.
Glucose is broken down into pyruvate, acetyl CoA and fatty acids. Fatty Acids are used as fuel by all cells in the body. They provide energy for many metabolic reactions including those that convert food into energy such as glycolysis.
How Does Glycolysis Work?
The process of glycolysis takes place in cells, such as those found in our muscles, and even in some bacteria. This process is the first part of cellular respiration, which converts carbohydrates and oxygen into a usable form of energy for the cell.
Glycolysis happens in the cytoplasm of cells, which is the area between the inner and outer membrane of the cell. This is the area where the cell is most active in chemical reactions.
As we discussed above, this process begins with the breakdown of glucose into two pyruvate molecules. This happens through a series of chemical reactions. These involve enzymes that speed up these reactions, which are critical to sustaining life. The purpose of these reactions is to produce adenosine triphosphate (ATP).
This is important because ATP is a “high-energy” molecule. Cells can use this molecule for energy right away. For example, in muscle cells during strenuous activity, these molecules are used to allow the muscles to contract. This process of breaking down and releasing energy from glucose is called oxidative phosphorylation.
Why Is It Called Anaerobic?
The second part of cellular respiration is anaerobic respiration. This process involves the breakdown of glucose without the use of oxygen. This type of respiration is called fermentation. During this process, lactic acid or ethanol (alcohol) is produced. However, both of these end products cause our muscles to feel fatigued because they build up and interfere with the contraction of our muscles.
Since this process does not use oxygen, it can only produce a certain amount of ATP. This is a limiting factor on how much energy is available for the cell. The byproduct of anaerobic respiration is lactic acid. This acid can build up during intense muscular activity and cause muscles to become fatigued.
The purpose of aerobic respiration is to produce a large amount of ATP. Also, it can only produce a small amount of lactic acid, which does not interfere with muscle contraction. So this process allows for longer periods of strenuous activity.
How Is It Used By The Body?
The body can only store a limited amount of glucose in the form of glycogen. This small supply of energy is found primarily in the liver and muscles. Once this supply is depleted your body will begin to metabolize more fats and carbohydrates which causes weight loss.
Anaerobic respiration occurs when your body’s demand for energy exceeds its ability to supply it aerobically. This usually happens during strenuous activity, especially exercise that is greater than 90 seconds in duration.
The body can perform anaerobic respiration for only short periods of time. If it continued for too long, the build up of lactic acid in the muscles would cause fatigue to set in and you would be unable to continue.
Exercising aerobically allows your body to perform at a high level without fatigue for longer periods of time. This is the main difference between the two types of respiration and why aerobic activity is more beneficial.
Tips For Exercising Aerobically
1.Lose weight if you are overweight.
2.Gradually increase your aerobic activity level if you are just beginning.
3.Warm up for 5 to 10 minutes before starting your activity and cool down afterward.
4.Perform aerobic activity for at least 30 minutes most days of the week. Your body needs time to recover in between workouts as well as build up your endurance and strength.
5.Exercise at a moderate intensity. You should be working hard enough that you are breathing harder and faster than normal but not to the point that you cannot speak more than a few words without pausing for breath.
6.Listen to your body. Stop if you feel pain and never force yourself to continue if you feel ill or experience pain of any kind. Obey the old saying, no pain no gain, and you will wind up on the sick list.
7.Remember to drink plenty of fluids before, during, and after your activity. Staying hydrated allows your body to operate at its peak performance level.
8.Don’t forget to warm up and cool down. This will prevent you from getting injured and it also helps get your body temperature back to its resting level gradually.
9.Always remember to breathe through your nose and out of your mouth when exercising. Breathing through your mouth can cause you to get dizzy or even pass out.
10.If you have any health concerns consult your doctor before starting an exercise program. Follow the doctor’s advice and if exercise is not recommended for your condition, find an alternative method to lose weight.
By applying these guidelines to your exercise routine, you will improve your aerobic fitness and see a reduction in your weight along with many other benefits.
Exercise Myths Busted!
Many myths exist about exercise and most of them are negative. Negative myths can keep you from starting an exercise program or cause you to stop. The following are some of the most common myths surrounding exercise and the facts that prove otherwise.
Myth: I’ve done a lot of exercise in the past and it didn’t help me lose weight.
Fact: Doing exercise is not enough to keep off the fat, you also need to eat less. Doing more exercise will only help if you also change your eating habits.
Myth: Getting in shape requires a lot of time in the gym.
Fact: You don’t need to spend hours in the gym to get in shape and stay that way. One hour per day is more than enough.
Myth: I’m too old to start exercising now.
Fact: It’s never too late to start exercising! Age is only a number and you’ll feel much better once you get in shape.
Myth: I’m happy with my weight and don’t have weight issues.
Fact: Many people think this but it isn’t true. Most people who say this are dangerously overweight but are in denial about their weight or just socially embarrassed by it.
The final myth that will be busted is…
Myth: Eating a lot of protein will make you bulk up.
Fact: This is the biggest myth about exercise and dieting. Eating a lot of protein will not bulk you up. If you do strength training with heavy weights, then yes, you may put on some muscle mass but if you just do a regular cardio routine then you will not put on any extra muscle mass.
A Word of Caution!
Once you have decided that you want to do some exercise you need to remember a few very important things before you begin. You need to know your limitations and listen to your body. Many people think that they can push through the pain but this is a very bad idea. If you feel any sort of pain while doing any form of exercise then you should stop immediately. Continuing to do exercise that causes pain is a sure fire way to getting injured and having to take a long time off or even being unable to exercise at all.
Make sure that you begin exercising slowly. Don’t go from 0 to 100 right away. Increase the duration and intensity of your workouts slowly as your body gets used to it. This is especially true if you are doing any weight training.
Warming up is very important before any exercise routine. It gets your blood flowing and muscles prepared for the work they are about to do. Never skip the warmup!
Last but not least, if you’re exercising because you have medical concerns such as high blood pressure, high cholesterol or any other medical condition it is very important that you consult your doctor before starting any exercise routine and that you find an exercise schedule that your doctor approves of.
Tips & Warnings
• Find an exercise that you enjoy doing. If you don’t enjoy it you’re less likely to keep with it.
• Make sure you’re eating a healthy diet along with your exercise routine.
Do you have any fears and misconceptions about exercise? Have you ever had a misconception that turned out to be false?
Tell us about it in the discussion thread.
Credit: This guide contains portions of a guide written by me (J_R_Miller) several years ago entitled “A Beginner’s Guide to Fitness”. I have modified it and added to it over the years but a lot of that original content is still intact.
Sources & references used in this article:
A Transcriptome Analysis Reveals that Hepatic Glycolysis and Lipid Synthesis Are Negatively Associated with Feed Efficiency in DLY Pigs by C Xu, X Wang, Z Zhuang, J Wu, S Zhou, J Quan… – Scientific reports, 2020 – nature.com
A feed-forward loop guarantees robust behavior in Escherichia coli carbohydrate uptake by A Kremling, K Bettenbrock, ED Gilles – Bioinformatics, 2008 – academic.oup.com
Definition of a novel feed-forward mechanism for glycolysis-HIF1α signaling in hypoxic tumors highlights aldolase A as a therapeutic target by G Grandjean, PR De Jong, BP James, MY Koh… – Cancer research, 2016 – AACR
Molecular intricacies of aerobic glycolysis in cancer: current insights into the classic metabolic phenotype by S Ganapathy-Kanniappan – Critical reviews in biochemistry and …, 2018 – Taylor & Francis
The reverse Warburg effect: aerobic glycolysis in cancer associated fibroblasts and the tumor stroma by S Pavlides, D Whitaker-Menezes, R Castello-Cros… – Cell cycle, 2009 – Taylor & Francis