American Society of Exercise Physiologists
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Issue: #3 March 2009
Dear Tommy,

Thank you for being part of our community. ASEP is the specific voice for (historically under-represented) Exercise Physiologists. Please use this Newsletter as a link to ASEP resources from scientific journals to professional papers, to employment and related opportunities. And be sure to click on "More On Us" at the left for the ASEP-newsletter's parent web site.
Also, members please consider the ASEP Annual 2009 DUES Renewal Notice on the ASEP web site.  

Finally, don't miss the Annual ASEP Conference coming April 2-4, in Wichita Falls, Texas, 2009! Details available at
-Lonnie Lowery and Jonathan Mike, ASEP-Newsletter Editors 
 Editor's Corner

editorialASEP 2009 National Conference: Making Fitness Functional: Just One Month Away! 

As the time is now near, we are again letting Newsletter subscribers know that the Annual ASEP Conference will be held in Wichita Falls, TX on April 2nd through the 4th, 2009. Information can be easily downloaded by browsing the web site. Further, there are now specific online documents and web pages on the ASEP site that will make your participation easy. Below are key links.
Don't miss this vibrant event with its number of new and exciting aspects. It is sure to benefit Exercise Physiologists and related professions to an all-new degree. 

Yours in health,
Dr. Lonnie Lowery,
ASEP-Newsletter Editor
Ask the EP 
Q. What are some explanations of fatigue regarding muscular contractions?  

A. Fatigue is usually perceived as any reduction in physical or mental performance. For the exercise physiologist, the word has a more restricted meaning. In the case of isometric contractions, force is a suitable outcome measure. However, when one considers dynamic contractions, "contractile response"can replace "force". This includes shortening, power, or velocity of shortening. The rate of fatigue depends on the muscles employed, the relative intensity of the exercise, and whether or not the contractions are continuous or intermittent. Although there is no singular cause of fatigue, it is task specific and its causes are multifaceted and vary from occasion to occasion. However, when discussing various aspects of training, fatigue can be described as failure to maintain the expected force, or the inability to maintain a given exercise intensity or power output level (Meeesen 2006).                         
There are two types of fatigue: peripheral and central. Fatigue during exercise is often due to impairment within the active muscle themselves, in which case fatigue is peripheral to the central nervous system.  Specifically, the muscle contractile proteins are not responding to their neural stimulation. Depletion of muscle glycogen (for fuel) is thought to be an important factor in peripheral fatigue, especially during prolonged exercise (Jentjens, 2003).Peripheral fatigue also encompasses events that occur independently of the CNS, including disturbances to axon terminals, neuromuscular junction, excitation contraction coupling, and contraction itself. Interestingly, this is where the majority of fatigue originates. Recently, strong evidence suggests the central fatigue hypothesis as an exercise-induced increase in extracellular serotonin concentrations in several brain regions contributed to the development of fatigue during prolonged exercise.  (Meeesen 2006).          

Central fatigue is concerned with the descending motor pathways from the brain and spinal cord. Bishop and colleagues (2008) explain that brain messages may signal reductions or complete cessation of exercise performance. The central fatigue hypothesis suggests that the brain is acting as a protective mechanism to prevent excessive damage to the muscles.During contraction in athletic competitions, muscular fatigue usually appears to be a peripheral phenomenon and due to fatigue of the muscles. The central nervous system and the associative motor neurons and neuromuscular junction appear to be far superior to skeletal muscle in maintaining function. However, as evidence suggests, the CNS can become a major contributor of fatigue function during exercise, as the CNS may operate to limit performance of muscles, thereby protecting the heart, brain, and other vital organs from damage.                
Through the wonders of contemporary science and technology, a whole series of devices and techniques are becoming available to researchers. Many of these devices will be of assistance in understanding muscle fatigue, such as nuclear magnetic resonance (NMR), positron emission tomography (PET), and near infared spectroscopy (NIRS). However, further research is warranted on these techniques with working muscles, brain, and other tissues during exercise.Denervation Apoptosis of muscle fibers, re-innervation of surviving fibers
  1. Bishop PA, Jones E, Woods AK. Recovery from training: a brief review: brief review.J Strength Cond Res. 2008 May;22(3):1015-24.
  2. Jentjens, R, & Jeukendrup, A. (2003). Determinants of post-exercise glycogen synthesis during short-term recovery. Sports Medicine. 33(2):117-144.
     Meeusen R, Watson P, Hasegawa H, Roelands B, Piacentini MF. Central fatigue: the serotonin hypothesis and beyond.Sports Med. 2006;36(10):881-909


~Jonathan Mike, CSCS, USAW, NSCA-CPT

Doctoral Student, Assistant Editor

Opportunities Related to Exercise Physiology
Saratoga Cardiology Associates... Full-Time Monday-Friday position to join our medical team located in upstate New York. Candidate must provide a safe and effective cardiac rehabilitation program....more information...

The Department of Kinesiology at the University of New Hampshire... is currently seeking applicants for a tenure track appointment in Exercise Science at the Assistant or Associate Professor level. ...more information...
NOTE: ASEP Board of Directors with approval of The Center for Exercise Physiology-online developed the "EPC Petition Guidelines" for doctorate exercise physiologists to become Board Certified.
Hotel Accommodations for the ASEP 2009 Conference (CLICK HERE)

Thank you for perusing our opinions, facts and opportunities in this edition of the ASEP-Newsletter.

Lonnie Lowery
American Society of Exercise Physiologists

All contents are copyright 1997-2007 American Society of Exercise Physiologists.

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