If You're Lifting and Running in the Same Session, Molecular Biology Explains Why One Adaptation Is Undermining the Other — and What Session Ordering Can Do About It.

The question of whether to combine resistance and endurance training in the same session has a molecular answer. When endurance exercise activates AMPK and resistance training activates mTORC1, these two signalling pathways are not complementary — they are antagonistic. AMPK phosphorylates TSC2, which inhibits Rheb, which reduces mTORC1 activity. The molecule that drives your aerobic adaptations is actively suppressing the molecule that drives your strength adaptations.

This is the concurrent training interference effect — and understanding it changes how athletes who need both qualities should structure their training week.

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The Hickson 1980 Observation

The interference effect was first documented systematically by Robert Hickson (1980, *European Journal of Applied Physiology*) in a study that combined strength training and endurance training in the same programme:

• Participants performing endurance training alone: VO₂max increased normally
• Participants performing strength training alone: maximal strength increased normally
• Participants performing both: VO₂max increased comparably to endurance-only — but strength gains plateaued and then declined from week 7 onwards

Hickson concluded that the concurrent training programme compromised strength development beyond a critical exposure point — the first published characterisation of what would later be explained through AMPK-mTOR molecular biology.

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AMPK-mTOR: The Molecular Mechanism

AMPK (AMP-activated protein kinase) is the cellular energy sensor — activated when the AMP:ATP ratio rises, as it does during prolonged moderate or high-intensity endurance exercise. AMPK's role is to restore energy homeostasis by:

• Stimulating glucose uptake and fatty acid oxidation
• Activating PGC-1α → mitochondrial biogenesis
• Inhibiting mTORC1 — reducing protein synthesis to conserve ATP for energy production

mTORC1 (mechanistic target of rapamycin complex 1) is the primary driver of muscle protein synthesis and hypertrophic adaptation. It is activated by mechanical tension (resistance training), insulin, and amino acids — and inhibited by AMPK.

When both training modalities are performed in close temporal proximity, elevated AMPK from endurance work suppresses the mTORC1 response to resistance training — blunting the anabolic signalling window that would normally be fully active 1–4 hours post-resistance training.

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Wilson 2012 Meta-Analysis: Quantifying the Interference

Wilson et al. (2012, *Journal of Strength and Conditioning Research*) meta-analysed 21 studies on concurrent training interference:

• Strength gains: Concurrent training produced 35% smaller strength gains than resistance training alone
• Lean mass gains: Concurrent training produced 39% smaller lean mass gains than resistance training alone
• Power output: Concurrent training produced the largest interference in power development (explosive strength)

Critically, Wilson's analysis also identified endurance modality as a key moderator:

• Running produced significantly greater interference than cycling
• Likely mechanism: the high eccentric loading of running produces additional muscle damage and inflammatory signalling that amplifies AMPK activation and reduces recovery capacity

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Managing the Interference: Practical Strategies

Strategy 1 — Separate sessions by 6+ hours: AMPK activation returns toward baseline approximately 3–4 hours post-endurance exercise. Separating resistance from endurance by 6+ hours allows AMPK to normalise before the mTORC1 stimulus is delivered. Morning endurance + afternoon resistance, or resistance morning + endurance evening, are both evidence-based separation protocols.

Strategy 2 — Sequence strength before endurance on same-day sessions: When same-day training is unavoidable, resistance before endurance is consistently superior to the reverse:

• Post-endurance resistance training: compromised neural drive, depleted glycogen, accumulated metabolic fatigue
• Post-resistance endurance training: some residual fatigue but AMPK is not yet elevated from resistance work alone, and aerobic adaptations are less sensitive to sequencing than strength adaptations

Strategy 3 — Replace running with cycling for lower-body concurrent training: For athletes combining lower-body resistance and endurance work, substituting cycling for running reduces the eccentric muscle damage component that amplifies interference. Cycling produces equivalent cardiovascular stimulus with substantially less structural interference on leg muscle adaptation.

Strategy 4 — Nutritional timing: Consuming carbohydrates and protein between concurrent sessions attenuates AMPK activation by restoring glycogen and providing amino acid substrate. A 40–60g carbohydrate + 20–30g protein recovery meal between morning endurance and afternoon resistance sessions reduces the AMPK elevation window and protects the subsequent mTORC1 response.

For athletes planning nutrient timing and macronutrient distribution across training days with both endurance and resistance sessions — and calculating meal composition to optimally bridge concurrent sessions — the macro meal generator at winsport.uk/tools/nutrition/macro-meal-generator creates individualised meal plans based on training type, session timing, and daily targets.

In your programme design — do you separate endurance and resistance sessions by 6+ hours when both are scheduled on the same day, or does training logistics override the interference management that would protect both adaptation streams?