Concurrent training done right - how to raise your aerobic ceiling without sacrificing the strength you've worked hard to build.
One of the most common concerns I hear from strength-focused clients when they start adding cardio: "I don't want to lose my gains." It's a legitimate concern - but with the right approach, it's almost entirely avoidable.
Concurrent training - doing both strength work and cardiovascular training in the same programme - has been studied extensively. The research is clear: yes, there is an interference effect, but it's much smaller and more manageable than most people fear.
When you combine strength and endurance training, the molecular signalling pathways that drive adaptation can partially conflict. Endurance work activates AMPK; strength work activates mTOR. These pathways aren't perfectly compatible, and in high doses, endurance training can blunt strength and hypertrophy gains.
But here's what the research also shows: the interference effect is largely modality-dependent and dose-dependent. Running causes significantly more interference than cycling. High volumes of cardio cause more interference than moderate volumes. And the effect is most pronounced in beginners doing everything at once.
"The interference effect is real - but it's not the enemy. Poor programming is the enemy."
The key principles for minimising interference while still building a serious aerobic base:
For HYROX prep, I typically structure training as: 3 strength sessions + 2 Zone 2 sessions + 1 HYROX-specific session per week. The Zone 2 work builds the aerobic base; the specific session practices race movements at race intensity. Strength is never abandoned - it's just periodised alongside the conditioning work.
Most people's cardio is too hard to be true Zone 2, and not hard enough to be genuinely high-intensity. They live in the middle - a grey zone that's metabolically stressful without providing the full benefits of either end of the spectrum.
True Zone 2 - where you can hold a conversation, heart rate around 130-150 bpm depending on the individual - builds mitochondrial density, improves fat oxidation, and develops the aerobic base that underlies everything else. It's also easy enough to recover from without impacting your strength training.
Start with two 30-45 minute Zone 2 sessions per week. Add one high-intensity session only when you have the base to support it.
Building your engine and keeping your strength isn't just possible - it's what the best hybrid athletes do. The key is smart programming: the right modalities, the right intensities, and the right amount of each. Stop treating strength and cardio as enemies. Programme them properly and they reinforce each other.
I specialise in HYROX preparation - building the engine, developing strength endurance, and making sure you cross the finish line strong.
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