Crossfit CrossFit Energy Systems and Metabolic Conditioning 1 — Questions and Answers
Question 1: Which energy system provides the primary fuel source during a maximal-effort sprint lasting 10 seconds or less?
- Oxidative (aerobic)
- Glycolytic (lactic acid)
- Phosphagen (ATP-PC) (Correct answer)
- Gluconeogenesis
Correct answer: Phosphagen (ATP-PC)
The phosphagen system uses stored ATP and creatine phosphate to fuel very short, maximal efforts up to about 10 seconds.
Question 2: During a 400-meter run at near-maximal pace, which energy system is predominantly active?
- Phosphagen
- Glycolytic (Correct answer)
- Oxidative
- All three equally
Correct answer: Glycolytic
The glycolytic system dominates efforts lasting roughly 30 seconds to 2 minutes, such as a fast 400-meter run.
Question 3: Which energy system is the primary contributor during a 20-minute moderate-intensity row?
- Phosphagen
- Glycolytic
- Oxidative (Correct answer)
- Phosphagen and glycolytic equally
Correct answer: Oxidative
The oxidative (aerobic) system is dominant for sustained efforts lasting more than about 2–3 minutes.
Question 4: CrossFit's broad time and modal domains are designed to develop fitness across all three metabolic pathways. Which statement best describes this approach?
- Specialize in the oxidative pathway only
- Train each pathway in isolation on separate days
- Use varied workouts that stimulate phosphagen, glycolytic, and oxidative systems (Correct answer)
- Avoid the phosphagen pathway to reduce injury risk
Correct answer: Use varied workouts that stimulate phosphagen, glycolytic, and oxidative systems
CrossFit intentionally varies workout duration and intensity so all three energy systems are regularly trained.
Question 5: What physiological adaptation most directly improves an athlete's capacity in the oxidative energy system?
- Increased ATP-PC stores
- Greater mitochondrial density (Correct answer)
- Higher creatine phosphate resynthesis rate
- Increased fast-twitch fiber recruitment
Correct answer: Greater mitochondrial density
Greater mitochondrial density allows more oxidative phosphorylation, directly improving aerobic capacity.
Question 6: Which CrossFit workout modality best exemplifies training the glycolytic energy system?
- A slow 45-minute trail run
- 5 rounds of max-effort 30-second Assault Bike sprints with 3-minute rest (Correct answer)
- A single heavy deadlift attempt
- A 10-minute light yoga flow
Correct answer: 5 rounds of max-effort 30-second Assault Bike sprints with 3-minute rest
Repeated 30-second near-maximal bursts stress the glycolytic pathway, which powers efforts in the 30-second to 2-minute range.
Crossfit CrossFit Energy Systems and Metabolic Conditioning 1
Which energy system provides the primary fuel source during a maximal-effort sprint lasting 10 seconds or less?