Research

Hormonal

Concurrent training for strength and endurance results in less adaptation (specifically reduced strength gains) compared to training for either modality alone, due to molecular interference between the PKB and AMPK signaling pathways.

If your primary goal is building muscle or strength, avoid long-duration endurance cardio immediately before or after your weights. If your primary goal is endurance, limit heavy resistance training. The molecular signals for muscle growth (PKB) and mitochondrial efficiency (AMPK) fight each other, so doing both optimally at the same time leads to inferior results for both.

GoodRefutesHIGH confidence
The classic work of Hickson demonstrated that training for both strength and endurance at the same time results in less adaptation compared with training for either one alone: this has been described as the concurrent training effect.
Keith Baar · Medicine & Science in Sports & Exercise · 2006

Why this rating

Based on a seminal 1980 study by Hickson and subsequent molecular validation described in the paper.

Source

Training for Endurance and Strength

Keith Baar · Medicine & Science in Sports & Exercise · 2006

DOI 10.1249/01.mss.0000233799.62153.19

narrative_reviewCited 179×
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DOI resolved against Crossref · corpus check 2026-06-10

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