exercise physiology

The Physiology of Performance – Part 1: Understanding the Hypothalamic-Pituitary-Adrenal Axis

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An unfortunate setback in the science of human performance is the large emphasis currently placed on muscle physiology as a means of maximizing performance. While obviously the muscles play a critical role in athleticism, the muscular system is completely at the whim of the nervous system; the junction of these two is known categorically as the Neuromuscular System.

In an ongoing effort to inform our athletes, parents, coaches, and general audience, we will be regularly detailing some specific segment of the Nervous System or the aforementioned Neuromuscular System. These are the areas of human performance which should be of primary interested to clinicians and academics rather than the simplistic if-A-than-B relationship of the muscular system as it works when viewed in isolation.

The Hypothalamic-Pituitary-Adrenal Axis (HPA Axis)

A critical element to training progress is the management, application, and adaptation to stress. Many will correctly point out that the improvements associated with practice and/or exercise come not in the training bouts themselves, but in the subsequent rest and tissue regeneration/ restoration. As a coach tries to monitor training loads and competition frequency to optimize the stress response, the HPA Axis performs this function internally.

The HPA Axis refers to the interaction of 3 fundamental structures. The Hypothalamus–a part of the limbic system which up/down regulates various hormone levels to maintain homeostasis (the drive to maintain stable internal states) in the body. Also it is comprised of the Pituitary Gland, which may be the most widely-known of the 3 parts; the pituitary is responsible for a wide array of physiochemical reactions like water retention, sexual development, and importantly for the HPA Axis, stress responses. Lastly, the Adrenal Glands function as the response to deviations in stress levels. Among others, the adrenals generate both of the stress hormones adrenaline and cortisol.

To bring these three structures together, think of it like this: the Hypothalamus wants to maintain a cohesive and stable environment among all internal systems. The pituitary manages stress and interacts with the hypothalamus to mitigate deviations to equilibrium. The adrenals generate the chemical messages (hormones) necessary for the stress response to occur and bring about homeostasis.

The HPA Axis and Performance

As alluded to, performance enhancement comes in the form of an adaptation to a stressor. In the case of an athlete, that stressor would be a rigorous training bout. With this in mind and a better understanding of the HPA Axis, it should now be a bit more obvious how managing and overcoming training stressors relates to a neuroendocrine system that deals directly with stress.

Through various methods, we can optimize the function of the HPA Axis to better deal with training stressors.

The role that the pituitary gland plays changes drastically in scale throughout adolescence, during puberty, and into the late teenage years. To maximize an athletes long-term potential, a great deal of care should be placed around ensuring an optimal stress load throughout this time.

On one hand, a young athlete may be under-stressed, as in the case of a single-sport and otherwise sedentary individual. This particular athlete’s long-term ability to generate stress hormones would blunted. In contrast to this, an athlete of the same age who competes year-round in the same sport, in addition to various other roles and obligations may be overstressed. A sign that over-stress is occuring is athlete burnout. The long-term biochemical response to prolonged periods of stress in adolescence can be a lifelong hypersensitivity to stress. This minimizes the total training load an athlete can undergo, lessening potential athletic adaptations, and increasing the overall likelihood of mood-related illnesses (like depression or anxiety).

The solution to this is an intermediate stress load to maximize stress tolerance and sensitivity. This can be done by ensuring a young athlete is engaged in multiple types of sports, only specializing in a singular sport with age.

As athletes develop they are still susceptible to changes in the HPA Axis. Recreational drugs and alcohol can impede the ability of the adrenals to produce adrenaline under normal stress environments like sport-specific training. This, in theory, seems to indicate a higher training load would be needed to achieve similar results.

Regardless of an athletes age, this stress response is a reason why lifestyle stress should be minimized during periods of high-stress in training. This is why it is common for elite athletes to minimize contact with boyfriends/girlfriends during the training leading up to a big event. Similarly, chronic sleep deprivation limits the downregulation of the stress hormone cortisol, leading to chronically elevated cortisol (stress) levels.

By simultaneously minimizing various stressors system-wide and effectively delivering a training response to overcome, an athlete’s short and long-term performance can be drastically enhanced. The scope of the HPA Axis goes far beyond athlete development. The HPA Axis also plays crucial roles in immune system function, emotional stability, and even in the activation of various genes.

 

 

Featured Fitness Content: Volume 46

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View the last edition of ‘Featured Fitness Content’ here.

Personal Training, Coaching, and Strength & Conditioning

138 | Dane Miller | Country Boys Can Survive Hosted by Zach Even Esh

Everything You Need To Know To Write Incredible Programs By Nancy Newell

Assess And Correct Leg Dominance  By Jennifer Pilotti via Breaking Muscle

Should Your Personal Trainer Be Licensed? By Jeremy Lau via Halevy Life

 

Weight Loss, Nutrition, and General Health

Himalayan Salt Lamps: Benefits and Myths By Helen West via Healthline

If it Fits With Your Micros: The Overlooked Key to Sports Performance By Zach Long

Restore Your Breathing and Improve Your Conditioning – Part 2 By Jim Smith

 

Strength Training, Powerlifting, and Bodybuilding

5 Advanced Squat Variations You Haven’t Tried By Meghan Callaway via Girls Gone Strong

Will Cardio Give Your Weight Training An Advantage?  By Dean Somerset

The Best Exercises You’re Not Doing for Shoulders – Cross Cable Flyes with “Y” Press  By Jim Smith

 

Motivation, Business, and Success

Freedom, fairness and equality By Seth Godin

The Salt Shaker Theory: 3 Principles of Effective Management By Mark Fisher via Business for Unicorns

 How to Set Boundaries with Clients By Michael Keeler via Business for Unicorns

 

Physical Therapy, Alignment, and Injury Prevention

How to Fix Rounded Shoulders  By Annette Verpillot via Strength Sensei

The Science Behind Cryotherapy, Ice Baths, Fat-Loss and Recovery  By Kevin Masson via John Rusin

 

Research

The No Barbell Experiment On Squat And Deadlift And Hip Thrust Strength: The Results  By Bret Contreras

 

Ruthless Performance Coaches’ Content

Lecture Takeaways: Ruthless Performance Methods & Practices for Peak Athletic Function By John Matulevich

 

Featured Fitness Content: Volume 44

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View the last edition of ‘Featured Fitness Content’ here.

Personal Training, Coaching, and Strength & Conditioning

Performance Programming Principles: Installment 2  By Eric Cressey

The 3 Main Goals of an Assessment By Dean Somerset

Step-by-Step Glute Training By Mike Robertson

 

Weight Loss, Nutrition, and General Health

Why You Might Not Need to Learn More About Nutrition By Mike Roussell

Carbohydrates – My Take on Carbs By Charles Poliquin

The Greatest Public Health Mistake of the 20th Century By Joseph Mercola

Honey Lemon Water: An Effective Remedy or Urban Myth? By Jillian Kubala via Health Line

7 Science-Based Health Benefits of Selenium By Jillian Kubala via Health Line

 

Strength Training, Powerlifting, and Bodybuilding

Are You Making These Strength Training Mistakes By G John Mullen via COR

Complete Core Questions By Michael Boyle

Get Tough: A Beginner’s Guide To Impact Training By Walter Dorey via Breaking Muscle

 

Motivation, Business, and Success

The Power of Accepting Personal Responsibility By Jen Comas via Girls Gone Strong

Truth: Half of What We Call ‘Fitness’ Isn’t Fitness at All By Lee Boyce

Before you design a chart or infographic By Seth Godin

Don’t create new content. Repurpose content. By Sol Orwell

 

Physical Therapy, Alignment, and Injury Prevention

[VIDEO] Recent Training and Evaluation Insights By Charlie Weingroff

Research

Science Is Self-Correcting – The Case Of The Hip Thrust And Its Effects On Speed By Bret Contreras

Flexion vs. Extension Intolerant Back Pain

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Of the individuals that participate in either the Ruthless Performance Ex Phys Interventions or our Posture Restoration & Injury Prevention Training, there is no across-the-board origin of pain or movement dysfunction at the hip or low back; in fact, client training histories run the gamut in activity level, training history, limb length, and so on.

So what is the common denominator among individuals with low back pain?

In short, there isn’t one singular origin, but rather there are two.

The more frequent of which is extension intolerance. This is common among what we in the Strength & Conditioning world refer to as ‘desk jockeys’, or any individual who is regularly in a resting position of spinal flexion. This includes desk workers, individuals with extended work commutes, TV watchers, and so on… Given our societal predisposition to these patterns, it should be relatively straightforward as to why this is so common.

In opposition to this is flexion intolerance. This is common among highly active individuals such as weightlifters, american football players, backpackers, manual laborers, and so on.

Assessing which category you fall in can usually be done simply with the above information, however there are some easy to perform physical tests as well. A hip extension machine is a great tool for diagnosing the more common extension intolerant back pain. Simply perform a standard hip extension, from here take notice to your range of motion and comfort levels. To assess flexion-intolerant back pain, perform several repetitions of the traditional sit-up or crunch. From here, reevaluate pain, comfort, and ROM.  If a hip extension machine is unavailable, any exercise in which spinal extension occurs (or spinal flexion for the flexion intolerant assessment) can be used.

These tests in congruity can determine a great deal about the cause and symptoms of any dysfunctions or abnormalities in the spine. Oddly enough the solution for both of these issues starts with the same series of correctives…

To gain more mobility in the requisite spinal segments (for extension and flexion), start with rotational spinal mobility to help ensure that as these capacities develop, the movement is coming from the correct areas of the spine (primarily thoracic rather than lumbar). Some exercises and drills which may assist here are quadruped t-spines, cross-over stretch, russian med ball twists, and so on.

From here you can progress into more specific drills to focus on your specific type of intolerance (i.e. focusing more on adding range to spinal extension drills or vice versa).

Spinal health can be simplified into a system of mathematical averages; to regain extension, flexion, or even to maintain a more neutral spine, adequate steps need to be taken to pull the posture in that direction.

For more information on our Posture Restoration & Injury Prevention Training or the Ruthless Performance Ex Phys Interventions, send us a message at RuthlessPerformance.com/contact.