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22 Dec 2025

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Understanding the Muscular System

evie

@evesgrace

Your muscles are way more complex than you might think!... Show more

muscle types:
• cardiac → the heart
→ not under
Conscious control
• involuntary → under
0
unconscious
control
→ cligesting.
food
• voluntary

The Muscular System Breakdown

Ever wondered why your heart beats without you thinking about it, but you have to consciously flex your bicep? That's because we've got three different muscle types doing completely different jobs in your body.

Cardiac muscle keeps your heart pumping 24/7 without any conscious effort from you. Involuntary muscles handle things like digesting your lunch - again, no thinking required. Voluntary muscles are the ones you actually control, like your biceps and triceps when you're lifting weights or throwing a ball.

Now here's where it gets interesting for athletes: not all muscle fibres are created equal. Type 1 fibres are your marathon runner's best mate - they're slow twitch, perfect for low intensity work, and incredibly resistant to fatigue. Type 2a fibres are the middle ground, ideal for 800m sprinters who need fast twitch power but can actually train these fibres to resist fatigue better. Type 2x fibres are pure explosive power for shot putters, but they'll tire out quickly.

Your muscles work in antagonistic pairs - whilst one muscle (the agonist) contracts to create movement, its partner (the antagonist) relaxes to allow that movement. Think bicep contracting whilst tricep relaxes when you bend your arm, or your quadriceps working whilst your hamstring chills when you kick a football.

Quick Tip: Knowing your muscle pairs helps prevent injuries - if you're training your quads hard, don't forget to work those hamstrings too!

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1 page

Understanding the Muscular System

evie

@evesgrace

Your muscles are way more complex than you might think! Understanding how different muscle types and fibres work together is crucial for sports performance and everyday movement.

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The Muscular System Breakdown

Quick Tip: Knowing your muscle pairs helps prevent injuries - if you're training your quads hard, don't forget to work those hamstrings too!