Harnessing the Power of Metabolic Pathways in Fitness

When it comes to physical fitness, understanding how our body produces energy is crucial. This energy production is categorized into three distinct metabolic pathways, each activated under different circumstances based on the intensity and duration of the activity. By understanding these pathways, you can tailor your output for optimal performance and results. It will also help you understand why the recent 500m Row Time Trial was so difficult. It’s just 500m right?

Let’s delve into each of these pathways and explore specific workouts tailored to them.

1. Phosphagen System

Duration: Short bursts (10-30 seconds)
Intensity: Very High

The phosphagen system, also known as the ATP-PCr system, is the primary energy source for very short-duration, high-intensity activities. It utilizes adenosine triphosphate (ATP) stored in the muscles, which is then replenished by creatine phosphate (PCr). *Why creatine is a helpful supplement!

Workouts for the Phosphagen System:

  • 100-meter sprint: A full-effort sprint over this short distance primarily utilizes the ATP-PCr system.
  • Max weightlifting: Lifting your one-rep max in exercises like the deadlift, squat, or bench press.
  • High jump or long jump: These explosive movements require maximum power in a short timeframe.

2. Glycolytic System (Lactic Acid System)

Duration: Short to medium (30 seconds to 3 minutes)
Intensity: High

The glycolytic system produces energy by breaking down glucose (from carbohydrates) in the absence of oxygen. It’s more sustained than the phosphagen system but leads to the production of lactic acid, which can cause muscle fatigue and burning sensations.

(Did you feel the lactic acid after the 500m row time trial?)

All energy systems are trainable, but athletes tend to especially notice when their lactic threshold increases … meaning, their body gets better at removing lactic acid, so it takes more work before you “feel the burn” which happens when lactic acid accumulates faster than the body can remove it.

Workouts for the Glycolytic System:

  • 400 to 800-meter run: These middle-distance runs push athletes into the glycolytic zone, especially if they’re running near their maximum pace.
  • Short CrossFit WODs: A series of exercises performed back-to-back with minimal rest in between, such as burpees, kettlebell swings, and box jumps.
  • 500m Row Time Trial

3. Oxidative System (Aerobic System)

Duration: Prolonged (More than 3 minutes)
Intensity: Low to moderate

The oxidative or aerobic system is the primary energy source for prolonged activities. It uses oxygen to metabolize carbohydrates, fats, and proteins to produce ATP. This system is the most sustainable but operates at a lower intensity.

Workouts for the Oxidative System:

  • CrossFit WODs over 3 minutes: Think 20min AMPRAP
  • Long-distance running: Marathoners or those engaging in 10k runs predominantly use the aerobic system.
  • Cycling: Long, steady-state rides, especially those lasting over an hour.
  • Swimming: Extended sessions of continuous laps in the pool.

Conclusion: Tailoring Workouts to Your Goals

At the heart of every workout lies a deep understanding of these metabolic pathways. As athletes, you don’t need to ponder over which system to train; that’s been planned for you. What’s essential is to understand the underlying energy systems being tapped. By grasping the mechanics of each pathway, you can approach your workouts with intention and precision, ensuring that you execute each movement and session optimally. Trust in the programming, focus on your execution, and witness the transformative power of informed fitness.



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