The Strength-Endurance Trap: Why Your Post-Run Lifting Session Is Sabotaging Your Gains
A Strength Coach's Reflection on the Misconception of Post-Endurance Strength Training
I recently watched a video featuring an ultrarunner discussing his training regimen. It highlighted a common misconception I've encountered throughout my 25+ years as a strength and conditioning coach who also participates in ultra-endurance events.
The athlete described a training approach many endurance athletes attempt: completing heavy resistance training immediately following a long-duration run. His rationale reflected a belief I've heard countless times – that by stacking these training modalities, one could somehow capture a unique adaptive response that combines the benefits of endurance and strength work, particularly when performed in a pre-fatigued state.
This approach represents a fundamental misunderstanding of exercise physiology that I've seen repeatedly in the endurance community. Many athletes believe that by training in a glycogen-depleted, neurologically fatigued state, they're somehow enhancing the training stimulus. They often describe seeking that "deep fatigue" as though it were the secret ingredient to performance breakthroughs.
What these athletes don't realize is that their physiology simply doesn't support this training structure. The body doesn't respond to training stimuli in an additive fashion—"endurance plus strength equals super-adaptation." Instead, competing physiological demands can actually interfere with one another, particularly when targeting different energy systems and neuromuscular patterns.
After extended cardiovascular exercise (even a relatively moderate 2-hour run), several physiological conditions make heavy resistance training significantly less effective.
The central nervous system experiences substantial fatigue following prolonged endurance exercise. This neurological fatigue directly compromises the ability to recruit high-threshold motor units – the fast-twitch muscle fibers essential for generating maximum force during heavy lifting. The result is diminished strength output and reduced training quality.
Extended running significantly depletes muscle glycogen stores, indirectly affecting heavy-strength training performance. While heavy, low-repetition lifting (1-5 reps) primarily relies on the ATP-PC (phosphagen) system rather than glycogen directly, the glycogen-depleted state impairs overall recovery capacity, inter-set recovery, and the ability to maintain quality across multiple sets. This systemic fatigue transforms what should be a productive strength session into a suboptimal workout with diminished returns.
The hormonal environment after prolonged running is particularly unfavorable for strength development. Extended aerobic exercise elevates cortisol levels, creating a catabolic state in which the body breaks down tissue rather than building it. Meanwhile, anabolic hormones crucial for muscle development are often suppressed, further hampering strength adaptations.
This phenomenon is well-documented as the "interference effect," where endurance training can impair strength adaptations when performed in close proximity, e.g., immediately post-endurance training. While strength and endurance training utilize different primary energy systems (ATP-PC for heavy lifting vs. aerobic for endurance), they compete for the same recovery resources and adaptive capacity. Research consistently shows that performing these contrasting training modalities with inadequate recovery between them results in compromised adaptations to both.
What's particularly interesting about this misconception is its persistence despite substantial evidence to the contrary. This misconception stems from the endurance athlete's mindset, which often equates discomfort with effectiveness. There's a certain logical appeal to the idea that more stress equals more adaptation. Still, this oversimplification ignores the complex, system-specific nature of how our bodies adapt to different training stimuli.
This isn't to say that ultrarunners shouldn't strength train – quite the opposite. Proper resistance training is invaluable for endurance athletes, potentially improving the economy of movement, reducing injury risk, and enhancing overall performance. But timing matters tremendously.
A more effective approach would be to separate these training sessions by performing them on different days or with substantial recovery time between them. Even 6-8 hours can make a significant difference. This allows the body to partially restore neural function, begin normalizing hormonal balance, and recover some of its overall systemic capacity before undertaking a different training stimulus.
If scheduling constraints make same-day training necessary, reversing the order would be more beneficial – performing heavy resistance training first, followed by endurance work. This sequencing allows the strength training to occur in a fresh, unfatigued state while accumulating the endurance stimulus afterward.
The dedication to comprehensive training that includes endurance and strength work is commendable. However, understanding the underlying physiology can help direct those efforts toward more productive outcomes. In this case, the science strongly suggests that immediate post-long-run strength training will not elicit the beneficial adaptations many athletes hope for.
Dive into the Research
Docherty & Sporer (2000) highlighted that neuromuscular fatigue from endurance exercise significantly decreases strength training performance.
Docherty, D., & Sporer, B. (2000). A proposed model for examining the interference phenomenon between concurrent aerobic and strength training. Sports Medicine, 30(6), 385–394.
Wilson et al. (2012) demonstrated that glycogen depletion from endurance training reduces performance and hypertrophy adaptations by limiting energy availability and increasing metabolic fatigue.
Wilson, J. M., Marin, P. J., Rhea, M. R., Wilson, S. M., Loenneke, J. P., & Anderson, J. C. (2012). Concurrent training: A meta-analysis examining interference of aerobic and resistance exercises. Journal of Strength and Conditioning Research, 26(8), 2293–2307.
Kraemer et al. (1995) found concurrent endurance and strength training resulted in elevated cortisol levels and reduced anabolic hormone responses compared to resistance training alone.
Kraemer, W. J., Patton, J. F., Gordon, S. E., Harman, E. A., Deschenes, M. R., Reynolds, K., … & Dziados, J. E. (1995). Compatibility of high-intensity strength and endurance training on hormonal and skeletal muscle adaptations. Journal of Applied Physiology, 78(3), 976–989.
