General Adaptation Syndrome
The human body is designed to establish and maintain a state of balance called, homeostasis. General Adaptation Syndrome (G.A.S.) is a term used to describe how the body responds and adapts to stress.
Exercise is referred to as “eustress” or as positive stress, because the adaptations required following exercise are ultimately going to improve the well-being of the client or athlete. By placing the body under carefully designed conditions of positive stress, we can elicit adaptations that will result in the client or athlete improving his/her health, physiological function and physical performance. For example, a progressive resistance training programme may elicit adaptations of increased muscular endurance, strength and size.
The body reacts to stress in three distinct stages:
1. Alarm Reaction
2. Resistance Development
3. Exhaustion
The aim of effective exercise programme design is for the client or athlete to undergo Alarm Reaction, which leads to Resistance Development, without reaching a state of Exhaustion.
Alarm Reaction stage:
This is the body’s initial reaction to the stress of exercise. As a result of the stress, a number of physiological and psychological protective processes are activated. When the body first engages in exercises or when alterations are made to an exercise programme the body is forced to adapt to the increased functional requirements placed on it. These requirements may involve the individual needing to adapt to increased loading (weight-training), prolonged activity (cardio), increased range of motion (flexibility), etc. In order to cope with the increased physical stress placed on the body, a number of immediate physiological responses occur, including: an increase in oxygen and blood supply as well as neural recruitment to the working muscles.
Initially, the body may be inefficient at responding to the demand placed on it during exercise. With time and repeated activity the body gradually increases its ability to meet the physiological demands placed on it by exercise.
When initiating a new exercise programme, clients or athletes may experience Delayed Onset Muscle Soreness (DOMS). This pain or muscular discomfort is often felt 24 to 72 hours after intense exercise or unaccustomed physical activity. It is believed that this phenomenon occurs due to muscular micro-tearing, as a result of the physical activity, especially involving eccentric loading. Pain receptors (called nociceptors) within the muscles connective tissues are stimulated after micro-trauma and inflammation, which results in the sensation of pain. One should distinguish between DOMS and acute muscles soreness (pain experienced whilst exercising). Old theories which linked lactic acid build up to DOMS have been discounted. DOMS is a the body’s way of protecting itself from further damage or injury being caused as a result of further exercise or activity. This is the body’s Alarm Reaction that leads to adaptation and Resistance Development.
Resistance Development stage:
This is where the body increases its functional capacity to adapt to the stressor. After repeated exercise and activity the human movement system will increase its ability to efficiently recruit muscle fibres and distribute oxygen and blood to the correct regions of the body.
Once adaptation has occurred the body will require increased stress in order to elicit the adaptation response. This is called the principle of overload.
Effective trainers are able to elicit this adaptation response, without pushing their clients or athletes into the Exhaustion stage through the scientific manipulation of the elements of conditioning and the load, volume and intensity of exercise. At an elite level, one of the most vital skills of a coach involves being able to push the athlete to his/ her limit, whilst allowing sufficient recovery to take place ,so as to see positive physiological adaptation.
Exhaustion stage:
Prolonged or intolerable amounts of stress can lead to exhaustion or distress. When a stressor is too much for the body to cope with, it can result in a ‘’breakdown’’ or injury. For example:
• Stress Fracture
• Muscle Strains
• Joint Pain
• Emotional Fatigue
These breakdowns or injuries can lead to the initiation of the cumulative injury cycle. This is where fatigue and/ or minor injuries lead to poor technique or exercise form, which ultimately leads to further and more severe injuries. In athletes a decline in performance may be a key indicator for exhaustion.
In order to avoid the Exhaustion stage it is important to structure the training programme using the principles of Periodization.
Periodization will be discussed in detail later in this section