Wednesday, February 9, 2011

Overtraining and Your Well Being

I.   Introduction
II.  The Immune System
         2.1 - Inflammatory Signaling Molecules
         2.2 - Natural Killer Cells
         2.3 - Neutrophils
         2.4 - Secretory Immune System
III.  Glutamine 
IV.  Cortisol
V.   Overtraining Symptoms
VI.   Overtraining Symptom Avoidance

Key words: amino acid benefits, antioxidant, arthritis, arthritis symptoms, glutamine benefits, joint pain, joint pain causes, knee pain, l-carnitine benefits, muscle growth, muscle recovery, overtraining, stress, stress relief

Exercise and weight training is a different form of stress that the body endures.  Every weight training or cardio session involving resistance causes injury to skeletal muscle fibers.  The injured muscle cells signal to the entire body that that some type of trauma has occurred.  Most of these responses are necessary for muscular development and fat loss.  However, if insufficient recovery time is given to muscles, these responses from the body may last much longer than necessary and cause more harm than good.  A large imbalance in exercise and recovery time is often referred to as overtraining syndrome.  In this blog, I’ll discuss some of the bodies’ reponses to overtraining and how that can negatively affect your work in the gym and your well-being.

P. S. - Please do not confuse overtraining with the normal soreness you get from good workout.  This blog is no excuse to start slacking off!!  I just want people to understand that there is such a thing as "too much working out".

Following skeletal muscle injury, various signaling molecules are released to orchestrate the cellular response to muscle injury.  Various growth factors attract satellite cells to the muscle injury site to facilitate the repair and growth of damaged muscle tissue and increase the size and number of proteins involved in muscle contraction. Molecules known as cytokines are also released to attract immune cells from the entire body to the injury site to remove cellular debris and heal the injured muscle cells.  These immune cells include macrophages, lymphocytes, neutrophils, and monocytes.  These cells continue to release cytokines (pro-inflammatory and anti-inflammatory) to attract other immune cells until the injury is healed. 

While this response is important for muscle growth, excessive exposure to pro-inflammatory cytokines by overtraining can result in muscle fatigue, loss in muscle protein, loss of muscle mass, and reduced muscle function (Reid and Li, 2001).  It can also induce a ‘whole-body response’, in which the brain induces sickness, vegetative, or recuperative behaviors, leading to mood and behavior changes that allow the body to get rid of the excess inflammatory factors (Smith, 2000).  Some of these behaviors include disinterest in exercise, reduced libido, arthritis, or a common cold (Smith, 2000). 

NK (natural killer) cells are a type of lymphocyte that play a major role in protecting the host (i.e. – you) from infections, by destroying infected or compromised host cells.  Many studies have characterized the changes in NK cell concentration following moderate to high-intensity exercise for short or long periods of time.  Following long periods of intense exercise, NK cell concentrations and cell activity decreased below normal levels, with the largest decrease being observed 2-4 hours after exercise (Mackinnon, 2000a; Mackinnon, 2000b).  Some high-intensity exercises included in these NK cell studies were:

1.  10-day interval running in military personnel (Fry et al., 1992).
2.  7 months of swimming training - 20-25 hrs/wk of pool training and 5 hrs/wk of training outside of the pool (Gleeson et al., 1995).
3.  4-wk intensified training in competitive swimmers (Gedge et al., 1997)

Neutrophils are another type of immune cell and acts as one of the first responders to an inflammation or injury in the body.  Like NK cells, many studies of investigated the effects of exercise on neutrophil activity.  And once again, these studies did show significant decreases in neutrophil concentrations following high-intensity exercise.  Here are some of the details from certain studies:

1.  The ability of neutrophils to engulf and remove bacteria (phagocytosis) was significantly lower among distance runners when comparing high-intensity training to moderate intensity training (Hack et al., 1994).

2.  Neutrophil activity, but not neutrophil number, was significantly decreased in swimmers in a 12-wk training program for a major competition (Pyne et al., 1995). 

These results show that intense exercise can not only reduce immune cell concentration, but also immune cell activity, resulting in greater overall vulnerability.

The secretory immune system in the upper respiratory tract is also affected by exercise and overtraining.  This system secretes a specific antibody, called Immunoglobulin A (IgA), which protects the respiratory tract from infection-causing pathogens.  However, several studies have linked decreases in IgA secretion with high-intensity exercise.  In a study by Mackinnon (1994), IgA secretion concentrations were compared between:
1.  Recreational joggers who ran on a treadmill for 40 min at 55% and 75% V 02 max, and
2.  Competitive distance runners who ran on a treadmill for 90 min at the same intensities.
(both considered 'moderate intensity', see HIIT blog for more info:

In both groups, IgA secretion concentrations did not significantly decrease after exercise.  However, runners that ran on a treadmill for 90 min at 75% VO2max on 3 consecutive days showed 20-50% decreases in IgA secretion after 3 days.  Post-exercise IgA levels on day 2 and 3 were also significantly lower than on day 1 (Mackinnon and Hooper, 1994). 

A separate study monitored IgA levels in elite swimmers over a 7-month period as they trained for the World Championship Trials.  Each week, the swimmers took part in 20-25 h of pool training and 5 h of training outside of the pool.  Control subjects were limited to a maximum of 4 h per week of moderate exercise.  The 7-month training resulted in a significant decrease in NK cell number and IgA levels (Gleeson et al., 1995).  This exercise-induced decrease in IgA level has also been proven to be a predictor for the development of upper respiratory tract infections (Mackinnon, 2000a).  

Glutamine is one of the most abundant amino acids in the body and is important for human metabolism (Smith, 2000).  Skeletal muscle produces the largest amount of glutamine, while the immune system, liver, kidneys and gastrointestinal tract require its use as fuel for its normal function.  Following intense exercise, glutamine is released from skeletal muscle tissue, resulting in low glutamine availability in plasma (Pedersen et al., 1998).  One theory is that due to the loss of glutamine following intense exercise, the immune system is unable to produce immune cells properly and efficiently, resulting in reduced immune function (Mackinnon, 2000a).  However, no studies have confirmed this theory.  While glutamine supplementation has been shown to maintain normal glutamine concentrations in plasma, it has not avoided the decrease in immune cell activity (Gleeson 2008).  However, one study has shown a reduced incidence of upper respiratory tract infection with glutamine supplementation in distance runners (Castell et al., 1996).  So, it is possible that the loss of glutamine after exercise may have an indirect effect on immune function.  However, the more likely reason for low glutamine availibilty is its role in maintaining blood glucose levels in the body.  Following muscle tissue injury, glutamine and other amino acids act as initiators of gluconeogenesis in the liver to produce new glucose for organs in the body (Smith, 2000).
The stress hormone, cortisol, also plays a role in maintaining blood glucose levels.  In response to exercise, cortisol is released from adrenal glands and promotes protein breakdown by inhibiting protein synthesis (catabolism).  This leads to the formation of amino acids (i.e. – glutamine and others) that are taken up by the liver and the subsequent stimulation of free fatty acids from adipose tissue for use as fuel (Brown, 2007).  Excessive cortisol can also make it more difficult to lose body fat (Epel et al., 2000).    

So what is the point of all of this, you ask?  Well, all of these reactions to exercise need time to run its course.  Without sufficient time off from exercise, these responses may become chronic and lead to overtraining syndrome.  As I touched on earlier, signs of overtraining include:
1.  High perceived stress
2.  Extreme muscle/joint pain
3.  Decreased performance in high intensity exercise
4.  Sickness
5.  Disinterest in exercise
6.  Reduced libido
7.  Arthritis
8.  Maintenance of body fat
Potential ways to reduce overtraining responses from the body include:
1.  REST!!  When you’re in the gym, hit it hard!  But, you need time to recover.

2.  Eating a diet full of vitamins and minerals; nutrients and antioxidants from a good diet will help to eliminate excess toxins in the body

3.  Vitamin C supplementation – if you aren’t getting enough Vitamin C in your diet, consider supplements to help bolster your immune system

4.  L-Carnitine supplementation – has been shown to improve muscle tissue repair by improving blood flow during and following exercise (no specific link to reducing cortisol levels; it basically minimize catabolism) (Kraemer et al., 2005).

4.  Listen to your body! – Now, don’t confuse overtraining with just some soreness from a good workout.  But if you’ve been working hard for 4-5 days and you’re really dragging or feeling some of the symptoms listed above, maybe a day off wouldn’t hurt.

5.  Try to keep stress levels low. Some methods may be yoga, meditation, deep tissue massage, etc.  But try to reduce stress in your life as much as possible.  Your body is dealing with more than enough stress with your exercise. 

Also, if you were recently sick, DO NOT work out again until your sickness is gone and you have regained your energy.  Then, ease yourself back into your workout routine on your first day back in the gym. 

Dr. O 
"I don't live to eat...I eat to live!"

Brown LE. 2007. Strength Training: Human Kinetics.
Castell LM, Poortmans JR, Newsholme EA. 1996. Does glutamine have a role in reducing infections in athletes? Eur J Appl Physiol Occup Physiol 73:488-490.
Epel ES, McEwen B, Seeman T, Matthews K, Castellazzo G, Brownell KD, Bell J, Ickovics JR. 2000. Stress and Body Shape: Stress-Induced Cortisol Secretion is Consistently Greater Among Women with Central Fat. Psycho Med 62:623-632.
Fry RW, Morton AR, Crawford GPM, Keast D. 1992. Cell numbers and in vitro responses of leukocytes and lymphocyte sub-populations following maximal exercise and interval training sessions of different intensities. Eur J Appl Physiol 64:218-27.
Gedge VL, Mackinnon LT, Hooper SL. 1997. Effects of 4wk intensified training on natural killer (NK) cells in competitive swimmers. Med Sci Sports Exerc 29:S158.
Gleeson M, McDonald WA, Cripps AW, Pyne DB, Clancy RL, Frickler PA. 1995. The effect on immunity of long-term intensive training in elite swimmers. Clin Exp Immunol 102:210-216.
Hack B, Strobbl G, Weiss M, Weicker H. 1994. PMN cell counts and phagocytic activity of highly trained athletes depend on training period. J Appl Physiol 77:1731-1735.
Kraemer WJ, Volek JS, Spiering BA, Vingren JL. 2005. L-Carnitine Supplementation: A New Paradigm for its Role in Exercise. Chemical Montly 136:1381-1390.
Mackinnon LT. 2000a. Chronic exercise training effects on immune function. Med Sci Sports Exerc 32(7):S369-S376.
Mackinnon LT. 2000b. Overtraining effects on immunity and performance in athletes. Immun Cell Bio 78:502-509.
Mackinnon LT, Hooper SL. 1994. Mucosal (secretory) immune system responses to exercise of varying intensity and during overtraining. Int J Sports Med 15:S179-S183.
Pedersen BK, Rohde T, Ostrowski K. 1998. Recovery of the immune system after exercise. Acta Physiol Scand 162(325-332).
Pyne DB, Baker MS, Frickler PA, McDonald WA, Telford RD, Weidemann MJ. 1995. Effects of an intensive 12-wk training program by elite swimmers on neutrophil oxidative activity. Med Sci Sports Exerc 27:536-542.
Reid MB, Li YP. 2001. Cytokines and oxidative signalling in skeletal muscle. Acta Physiol Scand 171:225-232.
Smith LL. 2000. Cytokine hypothesis of overtraining: a physiological adaptation to excessive stress. Med Sci Sports Exerc 32(2):317-331.


Anonymous said...

YAY!!! This was great! I definitely think my body induced sickness and then I got one of the worst colds I've had in 2 years. Today will be my first day back in the gym in a week and I will definitely take it slow and ease back into things. Thanks Dr. Nina!

Dozie Onunkwo, Ph.D. said...

No prob Tiff!! I hope you feel better after that week off. Even though you were forced into it, it was probably for your own good.

Kayla said...

Hey Dr D... I need more pics.. So much info.. You are really doing your research on these topics... So proud of you...

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