crossfit energy system

Energy Systems & Muscle Fibers type

Energy SystemsOverview

Maximum Rate of Energy Production

Maximum Duration of Energy Production

Old School …

Aerobic Anaerobic

200m 11% 89%400m 23% 77%800m 35% 65%1500m 45% 55%

*800m/1500m = Fran/Helen WOD’s

New School…

Aerobic Anaerobic

200m 29% 71%400m 43% 57%800m 66% 34%1500m 84% 16%

*800m/1500m = Fran/Helen WOD’s

% Aerobic Contribution

200m 400m 800m 1500m0

102030405060708090

NewOld

% Anaerobic Contribution

200m 400m 800m 1500m 0

102030405060708090

NewOld

When does the Switch Occur?

15-30 Seconds

Muscle Fiber Overview

Muscle Fibers Best to think of Muscle Fiber type as a Continuum

• LEFT = Pure Slow Twitch • RIGHT = Pure Fast Twitch • Middle = Many Blends and Variations

Characteristic of Fiber TypesSlow Twitch -Recruitment is Slow-Relaxation time is Slow-Force = Low -Fatigue Resistant = High - Cell = Aerobic Enzymes

Fast Twitch -Recruitment is Fast-Relaxation time is Fast-Force = High-Fatigue Resistant = Low- Cell = Anaerobic Enzymes

Athlete Examples

Slow Twitch Fast Twitch

Middle?

How do we know what Fibers we are Training???

Determining Factor = Force

Less Force = More Slow Twitch Fibers

More Force = More Fast Twitch Fibers

How does this Relate to Crossfit?

The Crossfit Problem…

Moderate to High Force application over a broad

amount of time.

Endurance events like Running or Cycling when an athlete is tired he/she can’t kick. (Recruit FT Fibers)

Crossfit makes the “tired” athlete Recruit (FT) Fibers whether they want to or not. At the expense of time.

Considerations for Untrained Novice Crossfit Athletes…

Body weight exercises could recruit (FT) fibers which will make them go anaerobic quicker.

-In this case, Athlete will need more time to recover between WOD’s. (Max Effort)

Fast explosive movements are an injury precaution because athlete have not established neural pathways to recruit the necessary (FT) fibers.

- Remember (ST) Relaxation Rate- Exercises Examples

- Down Hill Sprinting- Eccentric/Rebounding Plyo’s

Weak Athletes could still be “Aerobic Giants” a.k.a. have great Engines!

- Structurally they are too weak to exude the power to show you!

- Remember “Structural changes happen slower than metabolic.”

Must haves for the Elite Crossfit Athlete…- Absolute Strength - Very High Percent of Dynamic to

Absolute Strength (FT Fibers)- Great Aerobic Capacity with out

sacrificing Strength (Enzymatic Fight) - High Level of Skill (Technique)

- Great Neural Pathways (Recruiting FT Fibers)

The End