Posts Tagged ‘fast twitch fibers’

Preparing For Pelvic Floor Muscle Training (PFMT): What You Need To Know

January 6, 2018

Andrew Siegel MD  1/6/2017

Happy New Year!  At this time, many of us are trying to execute New Year’s resolutions.  Topping the list of most resolutions is getting into good physical shape.  A vital piece of this is pelvic floor fitness; in fact, pelvic floor muscle training was among the top five exercises recommended for general health and fitness in a recent Harvard Medical School report.

The next series of blog entries, written for both men and women, will enable you to achieve pelvic floor fitness.  Remember, Kegels are not just for the ladies!  This first entry discusses the fast and slow twitch muscle fibers that determine pelvic floor muscle (PFM) function, the adaptation principle and the distinction between strength, power and stability.  

Image below: Male PFM (left) and female PFM (right); notice their similarity.

1116_Muscle_of_the_PerineumAttribution: URL: https://cnx.org/contents/FPtK1zmh@8.108:b3YG6PIp@6/Axial-Muscles-of-the-Abdominal  Version 8.25 from the Textbook, OpenStax Anatomy and Physiology, 
Published May 18, 2016

Muscles 101

Muscles provide shape to our bodies and allow for movement, stability and maintenance of posture.  Most skeletal muscles come in pairs and cross bony joints—when one group contracts, it causes bending of that joint and when the opposing group contracts, it causes straightening of that joint (e.g., biceps/triceps).  When each contract equally, the joint is in a neutral position. The human body has three types of muscles—skeletal muscles that provide mobility and stability, smooth muscles that line the arteries, bladder, intestine, etc., and the unique cardiac muscle of the heart.  Muscles are composed of fibers that contract (shorten and tighten) and relax (lengthen and loosen).

The PFM are skeletal muscles that are comprised of fast twitch and slow twitch muscle fibers. Fast twitch fibers predominate in high contractile muscles that fatigue rapidly and are used for fast-paced muscle action, e.g., sprinting.  Slow twitch fibers predominate in endurance muscles, e.g., marathon running. The PFM have a constant tone (low level of involuntary contraction) because of the presence of slow twitch fibers. The fast twitch fibers allow for voluntary contraction. The PFM fibers are 70% slow twitch, fatigue-resistant, endurance muscles to maintain constant muscle tone (e.g., sphincter function and pelvic support) and 30% fast twitch, capable of rapid and powerful contractions (e.g., sexual climax, interrupting the urinary stream and tightening the anus).

Fact:  Aging causes a decline in the function of the fast twitch fibers, but tends to spare the slow twitch fibers.   

Muscle mass is in a dynamic state, a constant balance between growth and breakdown. With aging, muscle fiber wasting occurs as muscle breakdown exceeds muscle growth, adversely affecting function. Strength training reduces muscle wasting by increasing muscle bulk through enlargement of muscle fibers. This is true of all skeletal muscles, the PFM being no exception.

Adaptation Principle

Muscles are remarkably responsive to the stresses placed upon them.  Muscle growth only occurs in the presence of progressive overload, which causes compensatory structural and functional changes, a.k.a. adaptation. This explains why exercises get progressively easier in proportion to the effort put into doing them.  As muscles adapt to the stresses placed upon them, a “new normal” level of fitness is achieved.  Another term for adaptation is plasticity. Skeletal muscles are “plastic,” capable of growth or shrinkage depending on the environment to which they are exposed.

The PFM behave similarly to other skeletal muscles in terms of their response to exercise or lack thereof.  In accordance with the adaptation principle, it is advisable to increase number of repetitions and contraction intensity to build muscle PFM strength, power and endurance.  As much as our muscles adapt positively to resistance, so they will adapt to the absence of stress and resistance, resulting in smaller, weaker and less durable muscles.

Fact: Use It or Lose It. With a conditioning regimen, the PFM will thrive, optimizing their function.  When the PFM are neglected, they will weaken, impairing their function.   

Strength, Power and Stability

The goal of PFM training is to maximize the trio of PFM strength, power and stability. Strength is the maximum amount of force that a muscle can exert. With time and effort, PFM contractions become more robust, helping sexual function and improving one’s ability to neutralize stress urinary incontinence, overactive bladder and pelvic organ prolapse in females.  In males, command of one’s pelvic floor muscles can improve sexual, urinary and prostate health.  Power is a gauge of strength and speed (muscle force multiplied by the contraction speed), a measure of how rapidly strength can be expressed, of great benefit to sexual health and the ability to react rapidly to urinary/bowel urgency and stress urinary incontinence. Stability helps maintain vaginal tone, urinary and bowel sphincter function and pelvic organ support as well as contributing to the “backboard” that helps prevent stress urinary incontinence.

To be continued… Next week’s entry provides information on the process of building muscle PFM memory and how to develop PFM awareness.

Wishing you the best of health!

2014-04-23 20:16:29

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Dr. Andrew Siegel is a physician and urological surgeon who is board-certified in urology as well as in female pelvic medicine and reconstructive surgery.  He is an Assistant Clinical Professor of Surgery at the Rutgers-New Jersey Medical School and is a Castle Connolly Top Doctor New York Metro Area, Inside Jersey Top Doctor and Inside Jersey Top Doctor for Women’s Health. His mission is to “bridge the gap” between the public and the medical community.

Dr. Siegel has authored the following books that are available on Amazon, iBooks, Nook and Kobo:

 MALE PELVIC FITNESS: Optimizing Sexual & Urinary Health

THE KEGEL FIX: Recharging Female Pelvic, Sexual and Urinary Health 

PROMISCUOUS EATING: Understanding and Ending Our Self-Destructive Relationship with Food

Cover

These books are written for educated and discerning men and women who care about health, well-being, fitness and nutrition and enjoy feeling confident and strong.

Dr. Siegel is co-creator of the male pelvic floor exercise instructional DVD (female version is in the works): PelvicRx

 

 

 

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