GAS, ISRmt, and the Immune System: A Unified Model of Exercise Stress

New insights from Krüger et al. (2019) in Deutsche Zeitschrift für Sportmedizin show how exercise immunology mirrors classic stress biology. Let's connect the dots 🧠💪

🏋️‍♂️ Exercise = Immune Activation + Recovery Challenge

When you exercise, your immune system gets a workout too:

🧪 Acute bouts cause:

• A spike in leukocytes, NK cells, and cytokines

• Mobilization of T & B cells, neutrophils, monocytes

• Short-term oxidative stress & inflammation

But what happens next depends on dose + recovery…

⚖️ All stress responses, including exercise, have 3 possible outcomes:

1️⃣ Baseline recovery – immune system returns to where it was

2️⃣ Hormetic adaptation – immune function improves:

• Enhanced pathogen defense

• Increased naive T cells

• Reduced chronic inflammation

• Improved vaccine responses in older adults

3️⃣ Maladaptation – from overload or under-recovery:

• Impaired mucosal immunity (e.g. ↓ SIgA)

• ↑ Infections (URTI)

• T-cell exhaustion

• Inflamm-aging acceleration in older adults

This fits GAS (General Adaptation Syndrome) perfectly:

⚠️ Alarm → Resistance → Exhaustion (if energy runs out or stress stays high)

🔋 What's the key to adaptation?

Metabolic and bioenergetic resources.

No fuel = no immune regeneration.

No recovery = no gains.

Overload = maladaptation.

This is also reflected in:

• Mitochondrial ISRmt (Integrated Stress Response)

• Immune remodeling under exercise load

• Oxidative stress buffering via SOD, HSP72, cytokine shifts (IL-6, IL-10)

💡 Bottom line:

🧬 Train smart

🍽️ Fuel well

😴 Recover fully

🔥 Adapt better

📖 Ref: Alack, Pilat & Krüger (2019).Current knowledge and new challenges in exercise immunology. Dtsch Z Sportmed, 70(10), 250–260

#ExerciseImmunology #Hormesis #GAS #ISRmt #MetabolicHealth #Mitochondria #ImmuneFitness #OxidativeStress #RecoveryScience #Overtraining #Adaptation #SportsMedicine #TrainSmart