Overtraining and Central Nervous Fatigue

The idea of overtraining with a resulting decrease in performance is not a new phenomenon.  Russian scientists have been researching ways of staving it off for decades (1).  Overtraining is also relatively easy to recognise as long as you know what you are looking for.  Recognizing the symptoms is the easy part.  Identifying the physiological processes that cause it is a bit more tricky.  First the easy part.

Signs and Symptoms of Overtraining

There are two different types of recognizable overtraining, A-overtraining and B-overtraining (1).  Both have different accompanying symptoms.  A-overtraining is much tougher to recognize since the symptoms are less drastic and not easily noticeable (1).  B-overtraining, however, is easy to recognize.  There are many noticeable symptoms involving different physiological and psychological markers.  Among them are: increase in blood pressure, impaired coordination, decrease in weight, loss of vigor, chronic fatigue, mood swings, lack of motivation, reduced appetite, increased recovery time, decrease in immunity, sleep disturbances, and an elevated resting heart rate (1, 2, 4, 6).

Causes

The causes of overtraining are as varied as the signs and symptoms.  In reviewing the research it seems that the causes and effects become a cycle that can get out of hand of left unchecked.  Much research has been done on the oxidative stresses placed on the body during exercise.  While this is true and is necessary in order for the body to adapt, there is evidence that a decrease in the body's ability to handle this stress can lead to overtraining syndrome (OTS) (6).  When this happens there is often a decrease in performance as mentioned above.  While getting enough antioxidants through the diet to supplement the body's own stores is important, there is not sufficient evidence to suggest supra maximal antioxidant supplementation (9).  This is not as cut and dried as it seems.  In my opinion when one does not put as much effort into rest and recovery as they do into their actual exercise regime this sets them up to not be able to handle the oxidative stress and the accompanying OTS.

There has also been some research done on neurotransmitters in the brain.  Researchers hypothesise that when there is an increase in 5-HT (serotonin) there is a hastening of fatigue in the muscles, and vise versa.  The research that I have found has been limited to acute bouts of exercise rather than the accumulative effects of a long term exercise regime.  Again, this is not as cut and dried as it seems.  There are many different mechanisms at play here since there are many different systems that go into brain function.  Due to this it can be difficult to pinpoint the exact cause of OTS (7).

To be honest I couldn't care less what chemicals in my body are involved in the cause of the OTS.  What concerns me is what chemicals are effected by the OTS.

Consequences of Overtraining

This is probably the number one reason I am going to put more time into my recovery.  Many studies have shown that overtraining in both men and women causes a decrease in leutinizing hormone (2, 3, 4, 6, 8).  This hormone is central in creating sex hormones in both sexes.  In females decreased estrogen often leads to and decrease in body fat and amenorrhea, or a loss of menstruation.  In men it means a decrease in testosterone.  With this comes a decreased ability to build muscle mass, muscle catabolism, loss of sex drive, and an overall loss of awesomeness (4).  Unacceptable.  I don't lift to live with the symptoms of low testosterone.  I lift to be the very picture of male virility.  Lot's of chest hair and strong as hell. 

Since overtraining usually involves an impaired ability to recover trying to push through it may cause overuse injuries (6).  These can include shin splints, and stress fractures in runners, and muscle strains and tears in resistance training (4).  I, for one, don't want to be sidelined with an easily preventable injury.  I get so frustrated when I'm hurt I could strangle a drifter.  It sucks ass to say the least.  Sometimes, however, these small injuries can be a blessing in disguise.  I'm talking hooker-dressed-as-a-clown blessing in disguise.  Scary at first, but awesome in the end.

What To Do About It

The best way to combat overtraining is to prevent it in the first place.  This means adequate nutrition, monitoring all the warning signs and symptoms, and, first and foremost, proper rest and recovery (2).  Proper rest and recovery includes sleep and taking a proper amount of rest days.  When you sleep is when you release the most amount of growth hormone than at any other time of day (10).  Growth hormone is central in rebuilding and repair.  It's like a foreman on a construction site.  It gets all the different mechanisms for growth and repair into action.  "Get off your asses and build these walls!"  "Frank, this foundation is cracked!  How the hell should I know, fix it!"  "You guys see that blond broad with the huge cans walk by?  Yeah I yelled something but she didn't look."  Yep, that's growth hormone to a T.

Back to the injury part.  Hopefully you never get seriously injured in the weight room.  But sometime the little nagging injuries are the ones that signal it's time to back off for a bit.  This is where deload weeks come in.  Deload weeks are not weeks off per se.  They are weeks where you do the same lifts you normally do but just at lower weights and sometime lower volume (sets and reps).  The purpose of a deload week is to assist in recovery and recharge the batteries for the next few weeks of increased activities.  Taking regular deloads really helps to stave off overtraining and if you do them right with proper intensities (weight), volume, sleep amounts, and nutrition you may even come back stronger than when the deload started.

Wrap Up 

Overtraining is a part of training.  Sometimes it creeps up slowly and sometimes it rears its ugly, wart infested head in the form of an injury.  The old remedy of telling an overtrained person to stop being a pussy is very outdated and at times inappropriate.  With proper rest, recovery, nutrition, and a smart training plan with deloads sprinkled in, it can be avoided.

Overtraining is not, however, an excuse to slack in the gym.  If the weights you use rarely exceed the pink dumbbells you are probably not overtrained.  If you do tricep kickbacks and anything on a bosu ball, you are not overtrained.  I could go on but hopefully you get my point.  If you encounter someone who does the above mentioned exercise or something similar and complains about being overtrained then calling them a pussy is a viable and entirely appropriate remedy to the situation.

Sources:

Siff, Mel C. (2003). Supertraining. Denver, CO: Supertraining Institute.

Eichner, ER (1995).   "Overtraining: consequences and prevention." J Sports Sci. 1995 Summer;13 Spec No:S41-8.

Safarinejad MR, et al.  "The effects of intensive, long-term treadmill running on reproductive hormones, hypothalamus-pituitary-testis axis, and semen quality: a randomized controlled study."  J Endocrinol. 2009 Mar;200(3):259-71. Epub 2008 Dec 9.

Johnson MB, et al. "A Review of Overtraining Syndrome- Recognizing the Signs and Symptoms." 

J Athl Train. 1992; 27(4): 352–354.

 

Davis JM, et al.  "Possible mechanisms of central nervous system fatigue during exercise."  Med Sci Sports Exerc. 1997 Jan;29(1):45-57.

 

Tanskanen, et al.  "Altered oxidative stress in overtrained athletes."  J Sports Sci. 2010 Feb;28(3):309-17.

 

Meeusen R, et al.  "Brain neurotransmitters in fatigue and overtraining."  Appl Physiol Nutr Metab. 2007 Oct;32(5):857-64.

 

Hartman MJ, et al.  "Comparisons between twice-daily and once-daily training sessions in male weight lifters."  Int J Sports Physiol Perform. 2007 Jun;2(2):159-69.

 

Konig D, et al.  "Exercise and oxidative stress: significance of antioxidants with reference to inflammatory, muscular, and systemic stress."  Exerc Immunol Rev. 2001;7:108-33.

 

Fox SI.  (2004)  Human Physiology.  Madison, WI: McGraw Hill.