Homeostasis is one of the most remarkable and most typical properties of highly complex open systems. A homeostatic system (an industrial firm, a large organization, or a cell) is an open system that maintains its structure and functions by means of a multiplicity of dynamic equilibriums rigorously controlled by interdependent regulation mechanisms. Such a system reacts to every change in the environment, or to every random disturbance, through a series of modifications of equal size and opposite direction to those that created the disturbance. The goal of these modifications is to maintain the internal balances.

• Is there sport-specific homeostasis ?

There are homeostatic phenomena in sports training such as the plateau in variable dose-response relationship between exercise training and performance, the stable principal components in elite swimmers’ urine metabonomics and an ultrastructural study on delayed-onset muscle soreness (DOMS). The homeostasis in sports training was supposed to be sport-specific so that it is called sport-specific homeostasis (SSH), and the SSH hypothesis was supported by our recent metabonomic studies on elite swimmers’ urine and our reviewing training adaptation, tapering, reduced training , detraining and calorie restriction.
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Athletes’ physiological systems might be classified as SSH-essential system (SES) which includes SSH-essential skeletal muscular subsystem, SSH-essential energy supply subsystem, SSH-essential neurological subsystem, SSH-essential oxidative-antioxidative subsystem (OAS), and so forth, and SSH-non-essential system (SNS) which includes SSH-non-sential skeletal muscular subsystem, SSH-non-essential energy supply subsystem, SSH-non-essential neurological subsystem, SSH-non-essential OAS, autonomic nervous systems (ANS), circadian system, psychological system and so on. The quality of SES homeostasis (SESH) represents sport capacity. The higher the quality of SESH, the higher the performance level. The quality of SNS homeostasis (SNSH) represents sport performance. For the given SESH, the higher the quality of SNSH, the more improved the sport performance.
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Athletes’ training might be classified into two kinds, the sport extraordinary training (SET) such as DOMS to establish the SESH of higher quality by destroying the former SESH of lower quality, and the sport ordinary training (SOT) such as tapering or reduced training to maintain SESH, and to establish and maintain SNSH. The training ladder should be SET1-SOT1-SET2-SOT2-…-SOTn-competition. The competition might be just a special SOT.

• Is there job-specific homeostasis ?

The homeostasis in work was supposed to be job-specific so that it is called job-specific homeostasis (JSH). The elite persons such as the record breakers of Guinness World Records might be of JSH of high quality.#
Persons’ physiological systems might be classified as JSH-essential system (JES) which includes JSH-essential skeletal muscular subsystem, JSH-essential energy supply subsystem, JSH-essential neurological subsystem, JSH-essential OAS, and so forth, and JSH-non-essential system (JNS) which includes JSH-non-sential skeletal muscular subsystem, JSH-non-essential energy supply subsystem, JSH-non-essential neurological subsystem, JSH-non-essential OAS, autonomic nervous systems (ANS), circadian system, psychological system and so on. The quality of JES homeostasis (JESH) represents work capacity. The higher the quality of JESH, the higher the work level. The quality of JNS homeostasis (JNSH) represents work performance. For the given JESH, the higher the quality of JNSH, the more improved the work performance. #
Job training might be also classified into two kinds, the job extraordinary training (JET) to establish the JESH of higher quality by destroying the former JESH of lower quality, and the job ordinary training (JOT) to maintain JESH, and to establish and maintain SNSH. The training ladder should be JET1-JOT1-JET2-JOT2-…-JETn-JOTn-….#
SET and SOT hasve been widely studied, the rules of which might apply for JET and JOT.

• How many kinds of homeostasis are there simultaneously for a person ? and how big the difference between them is there?

An elite part-time athlete might have at least two kinds of homeostasis, one SSH and one JSH. A record breaker of a Guinness World Record might have least two kinds of JSH, one full-time JSH and one part-time JSH.＃
If the two or more SSH-specific systems were so similar that they can be integrated into a system in homeostasis, the corresponding sports might be called a sports group, and the corresponding homeostasis might be called sports-group-specific homeostasis (SGSH). The athlete in the SGSH might be simultaniously elite in two or more sports. For example, Ian Thorpe has been champions in swimming both in 200 and 400m, and Michael Phelps has been swimming champions in 100, 200 and 400m.

• How does homeostasis evolve in human life ?

The quality of homeostasis is becoming higher in developing and lower in ageing. The age when the homeostasis is of highest quality is defined as optimum age, h. The most possible life-span, y, of a person might be y=2h+1 if the developing and the ageing are supposed to be symmetric. In other words, the higher the quality of the homeostasis at the optimum age, the longer the life-span. #
A system in homeostasis reacts to every change in the environment, or to every random disturbance, through a series of modifications of equal size and opposite direction to those that created the disturbance. The higher the quality of the homeostasis, the stronger the disturbance resistance. Therefore, the longer the life-span, the stronger the disturbance resistance, and then the stronger the capacity of the chronic disease prevention, which might be the cause of “two sides of the same coin, ageing and disease”: http://www.nature.com/news/2007/071128/full/450603a.html?q=2#last-comment. #
For example, It has been observed that world class male athletes have increased life expectancy of [Sarna S, et al. Med Sci Sports Exerc. 1993 Feb;25(2):237-44.], and elite athletes from most sports disciplines have lower overall morbidity risk and enjoy better self-rated health in later years compared with the general population and matched controls who were healthy at young age chronic disease prevention [Kujala UM, et al. Sports Med. 2003;33(8):553-61.]

• * Does preconditioning such as dietary restriction and hypoxia enhance the quality of homeostasis?*

Preconditioning by sublethal stress can protect a biosystem from subsequent injury. That which does not kill you makes you stronger. In other words, preconditioning might enhance the quality of homeostasis of the related systems. For example, dietary restriction or hypoxia might enhance the quality of homeostasis of energy supply system.

• Might SOT or JOT be a therapeutic approach except in rehabilitation medicine or as a approach to spend the positive energy which defined as the difference of intake energy minus expenditure energy?

Balancing the food one eats with physical activity is one of dietary guidelines (http://www.cdc.gov/mmwr/preview/mmwrhtml/00042446.htm). In other words, there might be SSH or JSH specific nutrition absorption. If the positive energy might destroy SSH or JSH, SOT or JOT might be needed to spend it so that SSH or JSH can be rehabilitated. In other cases except in rehabilitation medicine, SOT or JOT might not be a therapeutic approach although SET or JET might be a therapeutic approach because it can enhance homeostasis quality.

**The topics are welcomed if they are related to homeostasis. Please contribute to this online discussion. *