Australian Yoga Journal - April 2016

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Body of knowledge

Understanding your muscle tissue

By Joe Miller

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ANATOMY

THERE’S A REASONyour yoga teachers say things like,

“Eccentrically contract your triceps to slowly lower

into Chaturanga,” instead of just, “Contract your

triceps.” It’s because there are three different ways

a muscle can contract, and how you utilise these

actions can affect strength and safety in a pose. So,

what is really going on inside the muscle tissue when

we flex, and why does it matter?

To get a feel for the mechanics in question, bend

your elbow. The biceps on the front of your arm

contracts to lift your forearm, creating a shortening

of muscle fibres, or concentric contraction. If you

keep your elbow bent, your biceps stays contracted to

resist gravity in a static (nonmoving), or isometric,

contraction. These types of contractions probably

feel familiar—they’re what you’d do if you wanted to

“make a muscle”.

Now slowly lower your forearm. You might

assume that the triceps muscle on the back of your

arm, which is responsible for straightening your

elbow, is working now. However, because gravity

pulls your forearm down, your triceps doesn’t need

to do anything. Rather, your biceps continues to

contract as it lengthens, resisting gravity. If it didn’t,

your forearm would simply fall. Such lengthening, or

eccentric contractions, are critical to controlling

many movements, from folding forward into

Uttanasana (Standing Forward Bend) to jumping

back to Chaturanga Dandasana (Four-Limbed Staff

Pose) to moving into an arm balance like Parsva

Bakasana (Side Crane Pose).

Targeting concentric, isometric, and eccentric

contractions in your asana practice will work your

muscles through their full range of motion, helping

you to develop balanced strength and lessening your

risk of injury. To understand these contractions, you

need to know what happens in your muscles when

they’re working. Muscle cells, or fibres, contain many

smaller strands called myofibrils, each of which in

turn is comprised of a series of contractile units called

sarcomeres. Within the sarcomere, two types of protein

filaments—thick filaments called myosin and thin

filaments called actin—overlap like interlaced fingers. ILLUSTRATION: MICHELE GRAHAM / PHOTO: RICK CUMMINGS; MODEL: LINDS AY GONZALEZ;HAIR/MAKEUP: BETH WALKER; TOP: VIMMIA; BRA: CHAMPION; BOTTOMS: PRANA

Get to know the different ways

your muscles contract to power

up your asana practice.

BICEPS

MUSCLE

MUSCLE

FASCICLE

MYOFIBRIL

SARCOMERE

MUSCLE CELL

(FIBRE)

MYOSIN

CROSS-BRIDGE

ACTIN

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april 2016

yogajournal.com.au