Psychosocial stress and vigorous physical exercise both increased stress hormones before extinction training, but groups did not differ in fear responding during retrieval 24 hours later, though psychosocial stress appeared to reduce fear renewal in a novel context and exploratory analyses revealed stress reduced context-dependency of extinction memory after reinstatement in men while exercise reduced overall responding in the extinction context.
Key Findings
Results
Both the stress and exercise interventions significantly increased heart rate, salivary cortisol, and alpha amylase levels compared to the control intervention.
120 healthy participants were tested (60 women, 60 men)
Three groups: vigorous-intensity treadmill running, psychosocial stress, and control
All physiological stress markers were significantly elevated in both active intervention groups relative to control
The stress intervention used a laboratory psychosocial stress induction protocol
The exercise intervention used vigorous-intensity treadmill running
Results
Fear acquisition was successful and fear responding decreased over the course of extinction trials for both skin conductance responses and pupil dilation measures.
Fear acquisition training occurred in context A on day 1
Extinction training occurred in context B on day 2, following the intervention
Both SCR and pupil dilation showed the expected pattern of fear acquisition followed by extinction
This was observed across all three groups
Results
The three groups did not differ in fear responding during contextual retrieval 24 hours after extinction training.
Retrieval and reinstatement testing occurred on day 3 in contexts A, B, and C
No significant between-group differences in fear responding were found during the retrieval phase
This null finding applied to both SCR and pupil dilation measures
Results
Psychosocial stress appeared to reduce fear renewal when participants were tested in a novel context (context C).
Fear renewal refers to the return of fear when retrieval occurs outside the extinction context
The novel context C was distinct from both the acquisition context A and the extinction context B
The reduction of fear renewal in the novel context was described as a finding with 'high therapeutic value'
This effect was observed at the group level across both sexes
Results
Exploratory analyses revealed that stress reduced the context-dependency of the extinction memory after reinstatement specifically in men, whereas exercise reduced overall responding in the extinction context.
These analyses were designated as exploratory in nature
The stress effect on context-dependency after reinstatement was sex-specific, observed in men but not women
Exercise effects were characterized by reduced overall fear responding in context B (the extinction context)
The reinstatement test was conducted in context A, B, and C on day 3
Background
Laboratory stress induction protocols have disadvantages including increases in negative affect, motivating investigation of physical exercise as an alternative modulator of fear extinction memories.
Physical exercise was described as a 'healthy and more positively experienced modulator of fear extinction memories'
Both stress and exercise share stress hormone-related mechanisms
The study was designed to compare these two interventions directly for their effects on contextual retrieval and generalization of extinction memories
Wolsink L, Wolf O, Merz C, Jentsch V. (2026). The effects of pre-extinction stress vs. physical exercise on contextual retrieval and generalization.. Psychoneuroendocrinology. https://doi.org/10.1016/j.psyneuen.2026.107793