Bioenergetics w/ Dr. Jacob Goodin | Pass the CSCS
Ever wondered how your body creates energy to sprint, lift, or even just stand up? In our latest Show Up Fitness Podcast episode, Dr. Goodin dives deep into bioenergetics—the science of how our bodies convert food and stored energy into usable fuel (ATP) to perform any task, big or small.
Let’s break it down in a way that makes sense.
Remember as Einstein said, “Everything should be made as simple as possible but no simpler
What is Bioenergetics?
Bioenergetics is how the body breaks down substrates like carbohydrates, fats, lactate, and proteins to resynthesize ATP (adenosine triphosphate)—your body’s energy currency. ATP has three phosphate groups attached to an adenosine molecule. When you break off that last phosphate, you release energy. That’s why ATP is essential for everything from blinking to deadlifting.
You can create ATP with oxygen (aerobic) or without it (anaerobic). According to Dr. Goodin, there are three main energy systems your body taps into depending on the intensity and duration of the activity:
- Phosphagen (ATP-PCr) System
- Glycolysis (Anaerobic and Aerobic)
- Oxidative (Aerobic Metabolism)
The 5 Gears of Energy Production (SUF-CPT Analogy)
In the SUF-CPT program—recognized by elite gyms like Equinox and Life Time Fitness—we teach bioenergetics using the analogy of a stick shift. Think of your energy systems like gears in a car:
- Gear 1 (0–10 seconds): ATP already in the muscle or blood gets used immediately. Super high intensity—think sprints, heavy lifts, or jumps.
- Gear 2 (10–30 seconds): Creatine Phosphate (Pcr or CPR system). ADP (adenosine diphosphate) is resynthesized back into ATP using creatine phosphate. This is still anaerobic. This is why it’s important to take our creatine monohydrate. Learn why Creatine is the best supplement to take HERE
- Gear 3 (30–150 seconds): Fast Glycolysis. Anaerobic glycolysis kicks in, using glucose to make more ATP. The byproduct? Pyruvate, which heads to the Cori cycle (a metabolic pathway that involves the cycling of lactate between muscles and the liver.)
- Gear 4 (2–3 minutes): Slow glycolysis—your body starts using oxygen to produce ATP more efficiently.
- Gear 5 (3+ minutes): Beta Oxidation. Full oxidation of fats and carbs. This takes longer but produces the most ATP. For example, breaking down one triglyceride can yield roughly 460 ATP, while glucose gives about 36 ATP. This is where the Krebs cycle kicks in also known as the citric acid cycle or TCA cycle, in the mitochondria (the powerhouse of the cell.)
💡 Pro tip from Dr. Goodin: Sitting is mostly oxidative (fat-burning), but standing up immediately shifts you into ATP-PCr mode. That’s how dynamic your body is.
Type I vs. Type II Muscle Fibers
- Type I (Slow-Twitch): Aerobic, endurance-based, used during longer, lower-intensity activity. Running, lifting weights 15+ reps, cycling, etc. Examples of these fibers can be seen in the rotator cuff, soleus (calf), and erector spinae (low back).
- Type II (Fast-Twitch): Anaerobic, explosive, used in lifting, sprinting, and high-intensity movements i.e. jumping, lifting heavy / power 1-10 reps, and a 200m sprint. Examples of these fibers would be our gluteus maximus (butt), rectus femoris (quadriceps), and latissimus dorsi (back).
Work to rest ratio’s for optimal recruitment of muscle fibers, and energy system.
NSCA Need’s Analysis is a game changer to better understand bioenergetics
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