1980
Concurrent interference identified
Hickson — the original study
42
Studies reviewed
Frontiers in Sports & Active Living, 2025
70%
Minimum intensity threshold
for Olympic lift skill transfer
If you've come from a CrossFit background and want to get serious about Olympic weightlifting, you've probably asked yourself: do I have to give up my WODs? The answer isn't a hard yes or no — but the science is clear enough that every competitive weightlifter should understand it.
The concurrent training effect
The core problem has a name: concurrent training interference. First identified by Hickson (1980), it describes what happens when you train for both strength and endurance simultaneously — gains in one can blunt gains in the other.
At the molecular level, the mechanism works like this: resistance training triggers the mTOR (mechanistic target of rapamycin) pathway, which drives muscle protein synthesis and the neural adaptations that make you stronger and more explosive. High-intensity conditioning work, on the other hand, activates AMPK (AMP-activated protein kinase) — an energy-sensing molecule that, when elevated, suppresses mTOR signalling and effectively tells your body to stop building muscle (Hawley et al., 2014; Coffey & Hawley, 2017).
“The metabolic stress of a hard WOD can chemically interfere with the exact adaptations you need to improve your snatch and clean & jerk.”
It's not just molecular — recovery is the real bottleneck
The molecular story is compelling, but researchers increasingly point to a simpler culprit: cumulative fatigue. When high-intensity conditioning is added to a weightlifting programme, total training stress rises faster than the body's ability to recover. The result is compromised neuromuscular performance, reduced training quality, and stalled progress — not because of AMPK per se, but because you're simply doing too much.
This matters especially for Olympic lifting. Unlike powerlifting, where a tired lifter can still grind out a squat, the snatch and clean & jerk are highly technical movements. Fatigue degrades coordination and timing in ways that are invisible on the bar but catastrophic for competition. Performing Olympic lifting movements under fatigue, time constraints, and loads less than 70% of maximum often does not effectively translate to Olympic weightlifting performance.
What does CrossFit-specific research show?
A 2020 systematic review in the Journal of Sports Science and Medicine (Schlegel, 2020) found that elite CrossFit athletes display excellent performance in Olympic weightlifting movements — but the research gap matters here. The same review noted that no concurrent training studies exist specifically addressing the development of Olympic weightlifting performance alongside endurance parameters. Most evidence comes from untrained or moderately advanced populations, not competitive weightlifters near their ceiling.
The implication: the interference effect is likely more pronounced the closer you are to your genetic and technical limits in the sport.
Can you still do both?
Yes — with intelligent programming. The evidence points to four clear strategies:
| Strategy | Evidence | Practical rule |
|---|---|---|
| Always lift before conditioning | 2025 review of 42 studies: strength-first sequence optimises neuromuscular adaptations | Snatch, C&J, and squats before any metcon — no exceptions |
| Separate sessions | Reducing molecular antagonism between endurance and strength adaptations (PMC, 2020) | Aim for 6+ hours between lifting and conditioning; different days is ideal |
| Favour low-intensity conditioning | mTOR inhibited after maximal sprints but not after moderate-intensity cycling (Hawley lab) | Zone 2 rowing, cycling, or skiing over high-intensity chippers |
| Taper WOD frequency pre-competition | Concurrent interference most costly during the peaking phase | Reduce WOD volume 4–6 weeks out; prioritise lifting specificity |
The honest bottom line
The science doesn't tell you to never do a WOD again. It tells you to be strategic. If you're a recreational lifter or early-stage competitor, some concurrent training is completely manageable. If you're pushing for a podium finish or chasing a national total, the research is clear: every high-intensity metcon you add is a small tax on your weightlifting progress.
“The further you are from your ceiling, the more you can get away with. The closer you are, the less you can afford.”
References
- Hickson, R.C. (1980). Interference of strength development by simultaneously training for strength and endurance. European Journal of Applied Physiology, 45(2–3), 255–263.
- Hawley, J.A. et al. (2014). Using molecular biology to maximize concurrent training. Sports Medicine, 44(Suppl 2), S117–S125. PMC4213370
- Coffey, V.G. & Hawley, J.A. (2017). Concurrent exercise training: do opposites distract? Journal of Physiology, 595(9), 2883–2896.
- Schlegel, P. (2020). CrossFit® training strategies from the perspective of concurrent training: a systematic review. Journal of Sports Science and Medicine, 19(4), 670–680. PMC7675627
- Frontiers in Sports and Active Living (2025). The effects, mechanisms, and influencing factors of concurrent strength and endurance training with different sequences: a semi-systematic review. PMC12885173
- BarBend (2025). How many times a week should you train the Olympic lifts? barbend.com