General adaptation syndrome (GAS)

General adaptation syndrome (GAS) is Hans Selye’s three-stage model of the stress response: alarm, resistance and exhaustion.^{1Haff and Triplett (eds.), Essentials of Strength Training and Conditioning, 4th ed., p. 600.},^{2Haff and Triplett (eds.), Essentials of Strength Training and Conditioning, 4th ed., p. 601.} It wasn’t developed for training, but became a foundation of periodization.^{1Haff and Triplett (eds.), Essentials of Strength Training and Conditioning, 4th ed., p. 600.} An NSCA coaching manual goes further, saying nearly all program designs are based on it.^{3National Strength and Conditioning Association, NSCA’s Basics of Strength and Conditioning Manual, p. 15.}

In the alarm stage, a new or harder stress, such as a heavier load or more volume, brings fatigue, soreness, stiffness and reduced performance.^{1Haff and Triplett (eds.), Essentials of Strength Training and Conditioning, 4th ed., p. 600.} During resistance, the body adapts; if the stress was appropriate, performance rises above its starting point, called supercompensation.^{2Haff and Triplett (eds.), Essentials of Strength Training and Conditioning, 4th ed., p. 601.} Stress that continues too long leads to exhaustion, overreaching and overtraining.^{2Haff and Triplett (eds.), Essentials of Strength Training and Conditioning, 4th ed., p. 601.}

In practice

• Raise the load once recovery has produced adaptation: repeating a load the client has already adapted to can’t drive further progress.^{4Rippetoe et al., Practical Programming for Strength Training, 3rd ed., p. 33.}
• Too little stress produces no change; too much overwhelms the client’s ability to adapt and lowers performance.^{4Rippetoe et al., Practical Programming for Strength Training, 3rd ed., p. 33.}
• Match training to the goal, following the principle of specificity: Rippetoe describes Selye’s premise as adaptation specific to the applied stress.^{5Rippetoe et al., Practical Programming for Strength Training, 3rd ed., p. 30.}
• Count life stress too: poor sleep, diet, work and relationships add to training stress.^{2Haff and Triplett (eds.), Essentials of Strength Training and Conditioning, 4th ed., p. 601.} Excessive loading, monotonous training and overly varied training can all push a client toward exhaustion.^{2Haff and Triplett (eds.), Essentials of Strength Training and Conditioning, 4th ed., p. 601.}