General Adaptation Syndrome (GAS)

The General Adaptation Syndrome (GAS), described by Hans Selye, models how an organism responds to any stressor in three stages, and it is the conceptual basis periodization borrows for training planning:

1. Alarm — The initial shock of a new or harder stressor; performance and function temporarily dip as the body mobilizes (fatigue, soreness, stiffness).
2. Resistance (adaptation) — Given adequate recovery and nutrition, the body adapts and rises above baseline — the basis of supercompensation, the window in which fitness has improved.
3. Exhaustion — If the stressor is too great or recovery too little, adaptation fails and function declines — the territory of overreaching and overtraining.

GAS supplies the logic for the core programming moves:

• Progressive overload keeps applying a sufficient alarm stimulus so adaptation continues; too little stress (or stopping) triggers reversibility.
• Recovery and deloads ensure the resistance/supercompensation stage is reached rather than driving into exhaustion.
• Periodization sequences harder and easier periods so cumulative fatigue is dissipated before it tips into exhaustion, and varies the stressor so the body keeps re-entering the alarm→adaptation cycle.

The practical takeaway: adaptation is not the workout itself but what the body does during recovery from it. Programs that never let recovery complete (chronic exhaustion) or never overload enough (no alarm) both fail.

• Three stages: Alarm (shock/dip), Resistance (adaptation/supercompensation), Exhaustion (breakdown).
• Adaptation occurs during recovery, above baseline — supercompensation.
• Progressive overload supplies the alarm; recovery/deloads secure the resistance stage.
• Too much stress + too little recovery ⇒ exhaustion (overreaching/overtraining).
• GAS is the rationale for periodizing hard and easy periods.

• periodization-overview — sequences stress and recovery on GAS logic.
• periodization — the classic periodization system this underpins.
• deload-weeks — planned recovery to stay out of the exhaustion stage.
• progressive-overload — supplies the recurring alarm stimulus.
• reversibility-disuse — what happens with too little stress.
• recovery-overview — recovery quality determines adaptation.