🟠 Moderate Evidence
The body’s capacity to adapt to physical demands depends not on eliminating stress, but on calibrating it precisely. According to the International Society of Sports Nutrition (ISSN) Position Stand on Antioxidants (2026), the physiological principle of hormesis—where moderate biological stress triggers beneficial adaptation—explains why sedentary individuals remain metabolically stagnant, why overtrained athletes plateau or decline, and why properly dosed training produces consistent gains.
Key takeaways
- Hormesis describes a U-shaped dose-response curve: too little stress causes metabolic stagnation, moderate stress triggers adaptation, and excessive stress causes maladaptation
- During moderate training, transient increases in reactive oxygen species (ROS) act as signaling molecules, triggering upregulation of antioxidant defenses and mitochondrial biogenesis
- Overtraining, poor sleep, and inadequate nutrition shift athletes into a maladaptive zone where ROS exceed buffering capacity, blunting performance gains
- Recovery is not passive—it is the active phase where the body converts stress signals into physiological adaptation
The Hormesis Curve: Stress Dose and Physiological Outcome
Relationship between biological stress intensity and adaptation response
Source: ISSN Position Stand on Antioxidants, 2026 | Georgian Medical Journal News
The Three Zones: From Stagnation Through Adaptation to Maladaptation
At low stress levels—such as during sedentary behavior—reactive oxygen species (ROS) production remains minimal and signaling pathways stay under-stimulated. According to the ISSN Position Stand (2026), this absence of challenge means the body has no biological reason to upregulate endogenous defense systems. The result is metabolic stagnation: mitochondrial function declines, antioxidant enzyme expression remains suppressed, and the body loses resilience to future stressors.
The moderate-stress zone is where physiological adaptation occurs. During appropriately calibrated training, transient increases in ROS act not as damage agents but as signaling molecules. This triggers a cascade of beneficial responses: upregulation of antioxidant enzymes (superoxide dismutase, glutathione systems), mitochondrial biogenesis, enhanced cellular repair pathways, and improved oxidative capacity. The ISSN Position Stand emphasizes that this is where exercise, thermal stress, and metabolic challenges produce their intended benefits—greater metabolic flexibility, performance improvement, and stress resistance.
The Overtraining Trap: When Stress Exceeds Recovery Capacity
Excessive stress—whether from overtraining, accumulated fatigue, or inadequate recovery—creates a maladaptive zone. When ROS generation exceeds the buffering capacity of antioxidant defenses, repair processes cannot keep pace with cellular damage. According to the ISSN Position Stand on Antioxidants (2026), this state is characterized by inflammation, persistent fatigue, declining performance, and blunted adaptation responses.
Critically, the ISSN notes that poor sleep, inadequate nutrition, and insufficient recovery can shift individuals into this maladaptive zone even if training volume appears objectively reasonable. Recovery is not a passive period of rest—it is the active phase where the body converts acute stress signals into lasting physiological adaptation. Without adequate recovery resources (sleep, macronutrients, micronutrients), even well-designed training fails to produce gains.
Recovery as an Active Adaptation Process
The hormesis principle reframes how we think about training and health. According to the ISSN Position Stand, the goal is not maximal strain or elimination of stress, but rather repeatable, recoverable stress that the body can respond to and grow from. Health and performance are built through the precise dosing of challenge and the active management of recovery.
This means that training prescription, nutritional support, sleep quality, and stress management are inseparable components of a single system. Isolating any one element—pushing hard without recovery, or attempting adaptation through rest alone—violates the fundamental principle of hormesis.
Health and performance are not built by eliminating stress, but by dosing it correctly and allowing recovery to convert stress signals into adaptation.
— International Society of Sports Nutrition (ISSN), Position Stand on Antioxidants, 2026
What this means
Frequently asked questions
Is all exercise stress beneficial?
Not all stress is equal. According to the ISSN Position Stand (2026), exercise stress must be calibrated to the individual’s capacity to recover. Stress that exceeds recovery resources—sleep, nutrition, time—becomes maladaptive rather than beneficial. The dose, not the activity itself, determines the outcome.
Can I supplement antioxidants to handle more training stress?
No—and doing so may be counterproductive. The ISSN Position Stand notes that transient ROS increases during training are signaling molecules, not waste products. Excessive antioxidant supplementation can suppress these signals and blunt the very adaptations training is meant to trigger. Whole-food sources of antioxidants (fruits, vegetables, whole grains) support recovery without saturating defense systems.
How do I know if I am overtrained?
Warning signs include persistent fatigue despite rest, declining performance despite consistent training, elevated resting heart rate, mood disturbance, and increased infection susceptibility. According to the ISSN Position Stand, these indicate that stress has exceeded recovery capacity. The remedy is not more training, but prioritization of sleep, nutrition, and reduced training load until recovery capacity is restored.
The hormesis principle transforms the conversation about health from “more activity is always better” to “the right dose of stress, plus adequate recovery, is optimal.” For sedentary populations, this justifies starting with modest, sustainable activity. For athletes and active individuals, it justifies ruthless prioritization of sleep and nutrition as performance-limiting factors equal to training intensity. As the ISSN emphasizes, the goal is not to eliminate biological stress—it is to master its dosing.
Source: International Society of Sports Nutrition (ISSN) Position Stand on Antioxidants and Oxidative Stress in Exercise and Sport, 2026
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Medically reviewed by Prof. Giorgi Pkhakadze, MD, MPH, PhD. Spotted an error? Contact the editorial team.
