Critical Commentary on General Adaptation Syndrome and Periodization

Context of the Discussion: This letter to the editor serves as a critical commentary on the paper by Cunanan et al. (2018), titled "The General Adaptation Syndrome: A Foundation for the Concept of Periodization."
Core Disagreement: The authors, Buckner et al., challenge the claim that the General Adaptation Syndrome (GAS) serves as an appropriate mechanistic model to conceptualize or provide a logical rationale for the periodization of resistance training.
Primary Narrative: Buckner et al. argue that while Cunanan et al. suggest the GAS is an "instructive framework" for training stimuli and functional enhancements, there is a lack of new experimental evidence to support the application of a syndrome caused by "various noxious agents" to human resistance exercise.

Focus on Originality: Buckner et al. explicitly focus on the original experimental papers by Hans Selye where the GAS was first developed, rather than the subsequent evolution of "perspectives" found in Selye's later reviews and books.
The Issue of Perspective: The authors argue that Selye’s later reviews [3–7] and books [8, 9] detract from the actual definition of GAS as established by initial experimental data.
Critique of Cunanan et al.’s Evidence: The authors assert that Cunanan et al. failed to provide new experimental data that would resolve fundamental concerns regarding how GAS is applied to resistance exercise, despite suggesting that the entirety of Selye’s work should be considered.

Foundational Definition: The GAS is described as a "syndrome" that manifests specifically when a "severe injury is inflicted upon the organism."
The Three Stages of GAS:
- Alarm/Reaction Phase: Initiated by exposure to damaging agents. In resistance training literature, this is often incorrectly equated to the start of a training program.
- Resistance Stage: A phase where resistance is built against the stimulus, and the initial symptoms of the alarm phase are no longer present.
- Exhaustion Phase: If the stressor persists beyond the organism's capacity to adapt, it leads to death.
Specific Physiological Markers of the Alarm Phase: Selye’s experiments on rats exposed to damaging agents (e.g., cold, traumatic injury, excessive muscular exercise, spinal shock, acute infections, and drug intoxications) produced extreme physiological responses:
- Rapid decrease in the size of the thymus, spleen, lymph glands, and liver.
- Complete disappearance of fat tissue.
- Edema formation, particularly in the thymus and loose retroperitoneal connective tissue.
- Accumulation of pleural and peritoneal transudate.
- Loss of muscular tone.
- Fall in body temperature.
- Formation of acute erosions (ulcers) in the digestive tract.
Involution of Lymphatic Organs: Selye identified the involution of lymphatic organs, particularly marked changes in thymus weight, as the most consistent finding of the alarm reaction.

Normal Exercise Response: Resistance exercise typically produces a level of muscle damage that confers a protective effect against future bouts (the repeated bout effect), which is not comparable to the systemic damage described in Selye’s alarm reaction.
Safety Argument: The authors contend that if normal human exercise actually produced a GAS, it would be considered dangerous and likely would not be a recommended activity due to the severity of the associated systemic symptoms.
Lack of Correspondence: There is no experimental data suggesting that the universal response observed by Selye (including organ involution and internal bleeding) occurs during standard human resistance training.

Selye’s Context for Exercise: In a 1976 review, Selye mentioned exercise twice:
- Once alongside severe stressors like "hydrotherapy, electroshock, insulin shock, Metrazol [pentylenetetrazol] shock, and nonspecific fever therapy."
- Once as a technique (alongside saunas and cold showers) to master "stress situations of everyday life."
Misinterpretation of Periodicity:
- Cunanan et al. argue that Selye implied a need for planned variation and rest (periodization) through his discussion of periodicity.
- Buckner et al. clarify that Selye’s discussion of periodicity in his 1950 review referred to physiological rhythms (e.g., pulse, sleep, sexual cycles, periodic cell renewal) and the dangers of persistently elevated hormones, such as those found in Cushing’s disease.
- Selye specifically noted that the spike in corticoids during brief muscular work does not produce "Cushingoid" manifestations and is unlikely to even produce a GAS.

Programming vs. Periodization: The authors dismiss semantic arguments regarding the definitions of "programming" and "periodization," focusing instead on the empirical outcomes of training studies.
Necessity of Variation: While acknowledging that rest is necessary, the authors argue that the literature does not support the necessity of complex variations in training variables for adaptation as an individual becomes more trained.
Management of Adaptation: If exercise did trigger a GAS, the authors suggest it would likely be managed by much simpler program structures than those advocated for in complex periodization literature.
Application to Athletes: For athletes, the authors acknowledge that planning is required to balance practice, training, and competition. However, this is viewed as a "logical decrease in one activity as another increases" rather than a validation of GAS-based programming.

Summary of Opinion: The authors conclude that the General Adaptation Syndrome is largely irrelevant to human resistance exercise.
Grounding in Evidence: The call for the field of sports science is to scale convictions regarding periodization to match actual experimental data rather than outdated or misapplied physiological theories.
Final Stance: The GAS describes a pathological state of severe injury and impending death, which fundamentally differs from the physiological process of adapting to exercise.