Catabolism vs. Anabolism: A Review in Biology

At a cellular level, your body is constantly undergoing chemical changes to sustain life. These reactions involve energy and are the sum of a series of chemical reactions known as metabolism. Metabolism can be classified into two categories of chemical reactions: catabolic (breaking down) and anabolic (building up). Both reactions are necessary to create the energy and building blocks for cells to function and maintain life.

This article discusses the differences between catabolism and anabolism and provides examples of exercises contributing to each state.

Differences Between Catabolism and Anabolism

Catabolism and anabolism are both metabolic processes involving energy, but catabolism releases energy while anabolism uses energy.

Definitions

At its most basic level, catabolism is the process of degrading or "breaking down," while anabolism is the synthesis or "building up," as follows:

• Catabolism is the process of breaking down complex macromolecules into simple molecules, such as carbon dioxide, water, and ammonia.
• Anabolism is the process of building up complex macromolecules, such as nucleic acids, proteins, polysaccharides, and lipids.

Catabolism releases energy when molecules are broken down, while anabolism requires energy to make more complex molecules.

Hormones

Hormones, the chemical messengers in the body, are responsible for catabolic and anabolic reactions. Hormones involved with controlling catabolism and anabolism include:

• Insulin
• Glucagon
• Thyroid hormone
• Cortisol
• Growth hormone
  

Both Processes Affect Energy Supply

Catabolism breaks down larger, complex molecules into simpler ones, releasing energy. Digestion is an example of a catabolic process. In digestion, complex molecules like carbohydrates and proteins are broken down into individual molecules of glucose or amino acids that can be absorbed and transported in the body.

Catabolism also takes place within the body, such as in glycogenolysis. During fasting, when blood glucose levels drop, stored glycogen in the liver is broken down to release energy.

Anabolism uses energy to create larger, more complex molecules. For example, amino or fatty acids may be combined to build proteins or lipids through anabolic pathways. Proteins become the building blocks for repairing or building muscle or other structures in the body.

For example, when you have an injury such as a cut, your body has to repair the wound through anabolic processes, which is why more energy is needed during illness or injury. The energy released by catabolic processes is utilized for anabolic processes.

The body constantly undergoes catabolic and anabolic processes, which release and utilize energy.

Catabolic Exercises

Any prolonged exercise is catabolic. However, most frequently, catabolic exercise is called aerobic exercise. The American College of Sports Medicine (ACSM) defines aerobic exercise as any activity that uses large muscle groups, can be maintained continuously, and is rhythmic. Aerobic or catabolic exercise includes:

• Cycling
• Dancing
• Hiking
• Jogging
• Long-distance running
• Swimming
• Walking
  

Anabolic Exercises

Anabolic exercises or exercises to build muscle are commonly referred to as anaerobic exercises. The ACSM defines anaerobic exercise as intense physical activity of a very short duration, fueled by the energy sources within the contracting muscles. Examples of anaerobic exercise include:

• Sprinting
• High-intensity interval training (HIIT) or circuit training
• Lifting weights or power-lifting
• Calisthenics (exercises that use your body weight for resistance)
• Pilates

A Note on Steroids and Performance-Enhancing Drugs 

Steroids and performance-enhancing drugs improve appearance by building muscle mass or improving athletic performance. The most widely studied class of steroids and performance-enhancing drugs are anabolic steroids, which can bolster the user's confidence and strength in the short term. However, using these drugs can also cause irreversible damage, including:

• Early heart attacks
• Strokes
• Liver tumors
• Kidney failure
• Psychiatric problems, such as depression with cessation and muscle dysmorphia

Additionally, users are at risk of contracting infections like viral hepatitis and human immunodeficiency virus (HIV) since these drugs are typically injected using needles.

What About Performance-Enhancing Dietary Supplements?

Many dietary supplements claim to improve your strength or endurance, increase your exercise efficiency, help you achieve a performance goal more quickly, and increase your tolerance for more intense training. Some of these supplements claim to be anti-catabolic in that they increase muscle mass more quickly.

The most common ingredients in sports-enhancing supplements include amino acids, protein, creatine, and caffeine. However, most studies on the effect of these supplements are based on single ingredients rather than the impact of combined ingredients and show mixed results or have too little research to support their claim.

The Food and Drug Administration (FDA) warns that dangerous hidden ingredients are an increasing problem in products promoted for bodybuilding. Consumers may unknowingly take products laced with prescription drug ingredients, controlled substances, and other ingredients that cause both short- and long-term health problems.

Summary

Anabolism and catabolism are constant metabolic processes responsible for bodily growth and repair. When it comes to exercise, catabolic exercises, such as running and swimming, break down muscle, whereas anabolic exercises, like strength training, build up muscle. Hormones are important factors that impact anabolism and catabolism.

While some sports can encourage the use of anabolic steroids to help increase muscle mass, short- and long-term risks are involved.