STACK Science: How Muscles Work and How To Make Them Work Better | STACK

Become a Better Athlete. Sign Up for Our FREE Newsletter.

STACK Science: How Muscles Work and How To Make Them Work Better

April 1, 2011

Must See Training Videos

Every athlete knows muscles power sports performance—they're the source of strength, speed and overall movement. But although lots of buzz words are tossed around in training rooms—like "muscle contractions," "fast-twitch fibers," "agonist and antagonist," etc.—how muscles actually function remains a mystery to many. And the fact is that understanding how muscles really work can help athletes make improvements in the weight room.

Fibers and Fascia
Muscles are composed of individual muscle fibers, which are customized cells designed to contract. The fibers form bundles, which in turn form an entire muscle. Each fiber has the ability to shorten to produce a contraction. As more muscle fibers are signaled to contract, the contraction gets stronger.

The fibers, bundles and entire muscles are interwoven with fascia—i.e., connective tissue. The fascia forms tendons, which connect to bones. When a muscle shortens, it applies force on the tendon to move a bone.  Larger muscles produce more force due to increased contracting ability, while longer muscles shorten more quickly for powerful movements.

Making It Work For You
Strength and size gains occur when muscles are challenged with bodyweight or resistance training exercises. When a muscle is fatigued, its fibers break down and adapt to the stress of an exercise—whether from high reps or heavy weight. The muscle then uses amino acids [in protein] to rebuild with an improved contraction system in each cell and to increase in size, which builds strength over its pre-training status. Thus, athletes must continually challenge their muscles by performing a variety of exercises and adding reps or weight to ensure progress.

Muscles are signaled to contract by the nervous system and are activated when calcium enters their cells. When the nervous system stops signaling muscle cells to contract, calcium leaves the cells and they go into a resting state. Small muscle groups—such as those found in the hand—require precise control and have a high degree of connection to the nervous system. Large and powerful muscles, such as the quads, have larger groups of fibers connected to the nervous system and produce more strength than coordination.

The interaction between the muscles and nervous system can be improved with a training program. This is one of the primary reasons why athletes achieve strength gains when they first begin to train.

Making It Work For You
Athletes should focus their training on functional movements that incorporate multiple muscle groups to ensure that muscles contract in a coordinated fashion during a movement. Increasing strength within a sport-specific movement directly relates to improved on-field performance. Also, functional training activates small stabilizer muscles, which are highly integrated with the nervous system to balance and stabilize the body.

Stay tuned to learn the differences between different types of muscle fibers and how they relate to performance.


Andy Haley
- Andy Haley is an Associate Content Director at STACK Media. A certified strength and conditioning specialist (CSCS), he received his bachelor’s degree in exercise science...
Andy Haley
- Andy Haley is an Associate Content Director at STACK Media. A certified strength and conditioning specialist (CSCS), he received his bachelor’s degree in exercise science...
More Cool Stuff You'll Like

Enhance Your MMA Skills With Heavy Rope Exercises

Top 5 Leg-Strengthening Exercises for Runners

3 Bad Consequences of Playing a Sport Too Much

Training for Mud Runs, Part 2: Strength Workout

Build a Game-Ready Chest

Athletes: Avoid These Four Upper-Body Exercises

Four Easy Tips for Building More Muscle

3 Specialty Barbells That Build Strength and Size

How Female Athletes Should Work Out

7 Grueling Grip-Training Exercises

Build Muscle: Strength Training Principles

Coaching Cues That Actually Work

How to Train as a Multi-Sport Athlete

5 Core Exercises That Work Your Entire Body

Use Combo Lifts to Increase Strength and Power

Increase Lacrosse Shot Speed With 3 Med Ball Exercises

Corrective Exercises for Knee Valgus

Football Players: Train Smart to Build Up Strength

Smart Exercises to Build Leg Strength

How to Perform the Power Clean

Get in Shape Fast With the 20-Minute Hurricane Workout

Inexperienced Lifters: How to Build Strength Now

Why You Should Get a Functional Movement Screen

Injury-Proof Your Body This Off-Season

The Unseen Advantage: Train Your Back for Power

Bodyweight Leg Exercises: Build Muscle Without Weights

An Introduction to Strength Training for Runners

10 Best Baseball Strength Training Exercises

Get Faster: Strength and Power for Speed

How to Get Big Arms: The Best 2 Exercises

The Ultimate Ab Workout for Athletes