Concurrent Strength and Endurance Training: Interference Phenomenon and How to Minimize It

Updated on 26 de June de 2026 by Adrián Escobar Morales

Combining strength training with resistance training in the same planning is something that most athletes do, either by necessity (team sports, triathlon, cycling) or by choice. However, for decades there has been debate about whether this combination generates interference in strength and hypertrophy adaptations.

Does resistance training really inhibit strength gains? Or is it a myth? The answer, as is often the case in sports science, is: depends. And nuances matter a lot.

What is the interference phenomenon in concurrent training?

He interference phenomenon describes the reduction in strength and hypertrophy gains that can occur when strength training is combined with resistance training, compared to strength training in isolation.

The most accepted explanation is chronic interference hypothesis: Resistance training activates molecular pathways (mainly AMPK) that are antagonists of the protein synthesis pathways activated by strength training (AKT-mTOR pathway). In other words, the molecular signals generated by both types of training “compete” with each other at the cellular level.

However, this interference It is neither inevitable nor systematic. A meta-analysis by Wilson and colleagues (2012) that analyzed 21 studies on concurrent training found that the magnitude of interference depends largely on how the training is organized.

Molecular mechanisms: why there may be interference

To understand how to minimize interference, it is useful to briefly understand what happens at the molecular level:

• He strength training activate the pathway AKT-mTOR, which initiates the synthesis of contractile proteins (myofibrils) and is the main driver of muscle hypertrophy. This synthesis remains elevated up to 72 hours after training.
• He resistance training activate the pathway AMPK, which increases mitochondrial density and aerobic adaptations, but inhibits mTOR — directly slowing muscle protein synthesis.
• Additionally, resistance training inhibits elongation factor EEF2, responsible for keeping protein synthesis elevated after strength training.
• If strength training is done with the depleted glycogen stores Due to a previous resistance session, the AKT-mTOR pathway is additionally impaired.

These mechanisms explain why the order and temporal separation of sessions are so important to minimize interference.

What factors determine the magnitude of the interference?

1. The type of resistance matters more than previously thought

One of the most relevant findings of the meta-analysis by Wilson et al. the thing is Not all endurance sports generate the same interference. When comparing athletics and cycling, they found significantly greater interference in athletes than in cyclists.

The explanation lies in muscle damage: athletics involves greater participation of the eccentric phase and of stretch-shortening cycle (SSC), resulting in more muscle damage and more competition with strength adaptations. Cycling, being predominantly concentric, produces much less muscle damage and therefore less interference.

Practical implication: If your main sport involves a lot of eccentric phase (running, jumping, changes of direction), the interference with your strength gains will be greater and you need to manage concurrent training more carefully.

2. Power is the most affected variable

Not all expressions of strength are affected equally. The meta-analysis found that the power — actions with medium-light loads at high speed — is significantly more susceptible to interference than maximum strength or hypertrophy.

The likely reason is that resistance training promotes a higher proportion of type I fibers (slow, oxidative), which are less efficient at producing force at high speed. Type II fibers (fast, explosive), which contribute the most to power, are relatively more affected.

This has direct implications for athletes who need to be explosive: Interference on power and speed of execution may be greater than 1RM indicates. An athlete can maintain maximum strength but lose explosive capacity without detecting it in a conventional 1RM test.

This is where the VBT provides information that 1RM does not: By measuring execution speed with submaximal loads you can detect drops in power and execution speed that would not be reflected in the 1RM until weeks later.

3. Resistance volume negatively correlates with strength

The meta-analysis found a moderate negative correlation between aerobic training volume and strength levels: The greater the volume of resistance, the greater the interference with strength gains. This makes physiological sense: a low strength demand maintained for a long time has very little similarity to the demands of strength training, and may even contradict the adaptations it generates.

4. VO₂max is not affected

Good news: when comparing concurrent training with isolated resistance training, the meta-analysis found no significant differences in VO₂max values. Strength training does not impair aerobic adaptations — as we saw in the article on strength training for cyclists, in fact it improves them.

How to organize concurrent training to minimize interference

The evidence points to concrete strategies to reduce interference to a minimum:

1. Prioritize HIIT over long-duration cardio

The trainings of high intensity and short duration (HIIT, sprints) They generate significantly less interference with strength and hypertrophy gains than long-duration cardio at moderate intensity. The reason is that HIIT is more similar to strength training in terms of neuromuscular and metabolic demands — it activates type II fibers more and generates fewer “endurance” adaptations that compete with strength adaptations.

Plus, HIIT doesn’t compromise VO₂max — it improves it just like traditional cardio but with less interference with strength.

2. Separate strength and endurance sessions by at least 6 hours

When it is not possible to train strength and endurance on separate days, temporary separation of at least 6 hours between sessions allows antagonistic molecular pathways (AMPK and mTOR) not to compete simultaneously. The greater the separation, the less interference.

3. If you train twice on the same day, strength first

When strength and resistance must be performed in the same session or with little separation in time, do strength training first. In this way, the mTOR pathway is activated with full glycogen stores and without prior inhibition of AMPK. Subsequent resistance training will not prevent protein synthesis from already starting.

4. Control the resistance volume

Since there is a negative correlation between aerobic volume and strength gains, in periods where strength and power are a priority, keep the resistance volume as low as possible compatible with the athlete’s objectives. More resistance sessions don’t always mean better aerobic fitness — and they can mean less strength.

5. Monitor the execution speed to detect interference early

Since power and execution speed are the variables most sensitive to interference, and 1RM can be maintained even when power is already dropping, Measuring speed with submaximal loads is the earliest way to detect if concurrent training is generating interference.

With the ADR Encoder You can record the speed of execution in each session and compare the evolution over time. If the speed under the same absolute load begins to drop steadily while the resistance volume is high, it is a clear sign that interference is affecting power before it is noticeable in 1RM. The ADR System app stores the history of each athlete in the cloud, facilitating this comparison session by session.

Summary: keys to concurrent training without interference

Conclusion

The interference phenomenon exists, but It is not inevitable nor does it affect all athletes equally. Its magnitude depends on the resistance modality, the type of cardio chosen, the aerobic volume, the temporal separation between sessions and the order of training.

The most sensitive variable is power and speed of execution — not 1RM. Therefore, in athletes who need to be explosive and who combine strength and endurance, monitoring execution speed is the most effective way to detect interference early and adjust planning before losses become significant.

Literature

Los siguientes estudios respaldan los datos y conclusiones de este artículo sobre entrenamiento concurrente y fenómeno de interferencia:

1. Wilson, J.M. et al. (2012). Concurrent training: a meta-analysis examining interference of aerobic and resistance exercises. Journal of Strength and Conditioning Research, 26(8), 2293–2307. See in PubMed →

Adrián Escobar Morales