Functional Roles of Muscles: Agonist Synergist Antagonist Stabilizer

NASM / ACE / ACSM / NSCA / ISSA / ISSA

To study the phenomena of disease without books is to sail an uncharted sea. To study books without patients is not to go to sea at all” – Dr. William Osler An Anatomy of Addiction Howard Markel

The following definitions can be found in the Glossary of the Essentials of Personal Fitness Training 7th Edition It's $199, I highly suggest NOT GETTING THE TEXTBOOK:

Agonist – Primary mover applying force during a movement.

Antagonist – Opposite of the prime mover (think of the antagonists in Romeo & Juliet, the Capulet & Montague Families.)

Synergist – Help provide movement for the prime mover (think of being, “in synergy,” meaning together.)

Stabilizer – Localized type 1 muscle fibers stabilizing the joints moving during the exercise.

Concentric muscle action – A muscle action that occurs when a muscle is exerting force greater than the resistive force, resulting in a shortening of the muscle. For example, during a pull-up, concentric is on the way up, when we exert force and typically want to breath out.

Eccentric muscle action – A muscle action that occurs when a muscle develops tension while lengthening. For example, during a squat, eccentric is on the way down (going against gravity), the easier portion (think Eccentric for EASY) and when we want to breath in.

Isometric muscle action – A muscle exerting force equal to the force being placed on it leading to no visible change in length. For example, while doing a plank or wall sit, these are both isometric contractions.

Understanding Movement:

The average personal trainer will quit within 12-months of getting certified. If you were to survey 100-trainers the importance of programming, you'd get a 100% agreeance in favor of having a strong understanding. Ask the same 100-trainers the importance of anatomy and they'd say it's not that important, “clients don't give a rats ass about what the sartorius does” (read all about that badass muscle here.) Trying to understand programming without a foundation in anatomy is like putting the cart before the horse -it ain't gonna work! Anatomy & programming go hand in hand. In order to understand how to program, you need to be proficient in anatomy FIRST.

I was at a John Rusin weekend seminar (we were hosting a PPSC for him) and he asked the group of 35 trainers, what are the 4-actions of the glutes? Only three trainers knew the answer (all show up interns.) That's the problem with the fitness industry, we obsess over client programs, but we're clueless on functional anatomy. Certifications won't test you on anatomy because it's HARD! If you fail anatomy, how are they going to make more money off you (gotta love the cert mills and their profits off the consumers ignorance)? Certs simply teach you how to recognize that the chest is the prime mover for a bench press, the triceps are the synergists, the posterior deltoids are the antagonist, and the rotator cuff muscles are the stabilizers. This is KINDA SORTA correct, BUT not 100%. Let Show Up Fitness teach you the WHY and the importance of functional anatomy.

*Core movement patterns: Vertical Push & Pull, Horizontal Push & Pull, Squat, Unilateral, hinge & transitional (jumps, farmers carry's etc.)

*CORE is making reference to the MAIN movement patterns; NOT core as in abdominal region.

When we analyze movement, we're looking at the biomechanics and functional anatomy. Let's breakdown the traditional movement patterns and their joint actions:

Vertical Push: Shoulder Press

Humeral action: Abduction. Plane of motion frontal. Muscles: Deltoid (anterior & medial.)

Elbow action: Extension. Muscles: Triceps.

Scapular action: Upward rotation. Muscles: Upper & lower traps, Serratus anterior.

TRAINERS looking to get certified ASAP, just memorize the italics for now:

Agonist: Deltoid. Synergist: Triceps & Upper / Lower traps. Stabilizers: Rotator Cuff (Glenohumeral joint), glutes and core (pelvis.) Antagonist: Latissimus Dorsi.

Common movement flaws WATCH BELOW: Anterior pelvic tilt & excessive thoracic extension. Cue external rotation of the feet and smack your client in the core to make sure core is braced. I like to say, “Pretend like Casper is going to punch you during one of these reps, make sure you are braced.”

Vertical Pull: Pull-Up

Humeral action: Adduction. Plane of motion: frontal. Muscles: Latissimus Dorsi.

Elbow action: Flexion. Muscles: Biceps.

Scapular action: Downward rotation. Muscles: Rhomboid Major & minor, Pectoralis minor, Levator Scapulae & latissimus dorsi.

Agonist: Latissimus dorsi. Synergist: Biceps & Rhomboids. Stabilizers: Rotator Cuff (Glenohumeral joint), glutes and core (pelvis.) Antagonist: Deltoid.

Common movement flaws: Limited ROM during the decent. You'll see bro's doing partial reps and trying to throw their chin over the bar. I like to cue, “Go all the way down until your elbows are straight. Hang for a second and repeat on my command& GO.” The following are two trainers from our Santa Monica location and they're doing trainer engaged pull-ups. This is a GREAT way to add value as a trainer and retain your clients.

Horizontal Push: Push-Up / Bench Press

Humeral action: Horizontal Adduction. Plane of motion: transverse. Muscles: Pectoralis Major, Anterior Deltoid.

Elbow action: Extension. Muscles: Triceps.

Scapular action: Protraction. Muscles: Serratus Anterior & Pectoralis Minor. The scaps SHOULDN'T be protracting during a bench. You want them locked down (depressed) to optimize force. During a push-up, they should be rolling off the ribs & protracting.

Agonist: Pectoralis Major. Synergist: Triceps & Serratus Anterior. Stabilizers: Rotator Cuff (Glenohumeral joint), glutes and core (pelvis.) Antagonist: Posterior Deltoid.

Here's an example of Show Up Fitness Interns in West Hollywood spotting one another during the lab portion. Classes are held daily at 10am as well as the online portion which can be seen HERE – become a trainer ANYWHERE IN THE WORLD when you SHOW UP!

Common movement flaws: Keeping their butt too high up in the air. I will grab my clients hips (always ask before you touch a client) and manually posterior tilt their pelvis while lowering it. Another common flaw is their arms (humerus) create a T instead of a V (if you stand over them you'll understand.) I like to say, “Face me and pretend I just called you a bad word. If you were to push me over, how would you set up and where would your elbows go?”

Horizontal Pull: Bent-Over Row (pronated and of equal hand placement to a horizontal push.)

Humeral action: Horizontal Abduction. Plane of motion: transverse. Muscles: Posterior Deltoid & Latissimus Dorsi.

Elbow action: Flexion. Muscles: Biceps.

Scapular action: Retraction. Muscles: Middle Trapezius & Rhomboids Major / Minor aka Mid Back.

Agonist: Posterior Deltoid & Latissimus Dorsi. Synergist: Biceps & Mid Back. Stabilizers: Rotator Cuff (Glenohumeral joint), erector spinae (lumbar extension isometric.) Antagonist: Pectoralis Major.

Common movement flaws: Flexing the cervical spine and driving through the upper traps. I like to say, “Drive through your elbows first (while placing my hands on their upper traps to cue depression.)”

Instructor BaRack Little showcasing the proper vs improper form for a bent-over row. Become a personal trainer or strength coach CSCS PREP HERE when you SHOW UP.

Squat: Goblet Squats

Femoral action: Extension. Plane of motion: Sagittal. Muscles: Gluteus Maximus.

Knee action: Extension. Muscles: Quadriceps.

Agonist: Quads (knee), Glutes (hip). Synergist: Certifications = HAMSTRINGS, but in actuality: Adductor Magnus (posterior fibers.) Stabilizers: Anterior & posterior core (erector spinae, rectus & transverse abdominals.) Antagonist: Psoas Major.

Common movement flaws: Knees caving in. The easier fix for this is to add light pressure to the lateral portion of the knee and cue them to push against you without losing the big toe, little toe and heel position of the foot. Another common flaw is to have the heels come off the ground. I like to put a pair of 2.5 or 5lb plates under their heels to create artificial dorsiflexion.

Hinge: Hip Thrust

Femoral action: Extension. Plane of motion: Sagittal. Muscles: Gluteus Maximus.

Knee action: LIMITED ROM ~Extension. Muscles: Quadriceps.

Agonist: Glutes. Synergist: Hamstrings & Adductor Magnus. Stabilizers: Posterior core (erector spinae & transverse abdominals.) Antagonist: Psoas Major.

Common movement flaws: Driving through the toes, a hyperextended neck and feet too close to their butt. I like to say have my clients find a foot position that allows for them to feel it in their glutes. This may be externally rotated, further away from their butt or having their toes go up in the air (dorsiflexed.)

If you want a complete breakdown on how to hip thurst, read my article that I wrote for STACK.COM HERE

Uni-lateral: Step – Up

Femoral action: Extension. Plane of motion: Sagittal & Frontal. Muscles: Gluteus Maximus & Gluteus Medius (frontal plane stabilization) Interns at our Austin 2-day Seminar learning how to get involved during the step-ups. Get $100 off our weekend seminars when your NASM-CPT. BUY YOUR TICKETS HERE FOR EARLY BIRD PRICING

Knee action: Extension. Muscles: Quadriceps.

Agonist: Agonist: Quads (knee), Glutes (hip). Synergist: Adductor Magnus. Stabilizers: Sartorius, TFL & Gracilis, anterior, lateral & posterior core (erector spinae, rectus & transverse abdominals, quadratus lumborum & obliques.) Antagonist: Psoas Major.

Common movement flaws: Similar to the squat, knee valgus, but also going to the toes during a forward lunge. This is one of the reasons I prefer a reverse lunch vs a forward lunge (and that every influencer on the planet has their clients perform 1,400 walking lunges.)

Transitional / Jump: Vertical Jump

Femoral action: Extension. Plane of motion: Sagittal. Muscles: Gluteus Maximus.

Knee action: Extension. Muscles: Quadriceps.

Agonist: Agonist: Quads (knee), Glutes (hip). Synergist: Adductor Magnus. Stabilizers: Posterior core (erector spinae & transverse abdominals.) Antagonist: Psoas Major.

Common movement flaws: TINKERBELL JUMPS. The number one way to let the world you have no idea how to train or an ounce of movement education, throw your arms behind your body while you are in the air like tinkerbell.

INTERNSHIP HOMEWORK:

Choose your favorite pattern. Record & post how to properly perform the exercise. How to regress & progress the exercise. What are common movement flaws? How would you get involved with your client? Ideally with a client as online instructor Gabby demonstrates here& If you want to become a personal trainer, SHOW UP FITNESS will help you become GREAT!