Should I Do Cardio or Weights First? Here's What Actually Matters

Posted by Tommy Halligan on June 25, 2025

If you've ever walked into the gym and thought, “Should I hit the treadmill before or after I lift?” you're not alone.

It’s one of the most common questions we get at The Lab Liverpool. And like most things in fitness, the answer is: it depends on your goal.

🎯 What’s Your Main Goal?

Goal	Best Order
Build muscle & strength	Weights first
Improve cardiovascular fitness	Cardio first
General fat loss or fitness	Weights first (in most cases)
Endurance performance (e.g. race prep)	Cardio first

🧠 The Science Behind It (Key Findings)

1. The Interference Effect

A widely cited 2012 meta-analysis by Wilson et al. found that combining cardio and strength in the same session can reduce strength, power, and hypertrophy gains, especially when cardio is performed first.

Muscle strength and hypertrophy were significantly compromised when endurance preceded resistance training.
Running had more interference than cycling (likely due to greater eccentric loading).
Performing both in the same session? Lifting first reduced the negative impact.

Key takeaway: If strength or muscle gain is your focus, lifting first allows you to produce more force, a key driver of adaptation.

2. Fatigue Affects Neuromuscular Performance

Research aside, our real-world experience shows this clearly.

When you’re already exhausted from high-intensity cardio, your ability to perform technically demanding lifts drops dramatically.

Fatigue masks your ability to produce force, maintain form, and execute movements with control. Even simple resistance work can suffer if aerobic fatigue creeps in too early.

💥 Real-World Coaching Insights

At The Lab, we coach strength-focused athletes, fat loss clients, and everyday gym-goers. Here’s how we typically guide clients:

✅ Weights First (for most people)

You train harder and more safely when fresh
You protect form, reduce injury risk, and get more out of your lifts

❌ Cardio First When Strength Is the Priority

It blunts force output, particularly in compound movements
You risk turning resistance work into low-effort “movement” rather than true strength training

⚖️ But it’s not all or nothing

If you’re training for aerobic improvement (like a 5K), flipping the order makes sense.
Your cardio performance will benefit from being done with fresh legs and lungs.

🧠 What We’ve Said Before…

In our article on Does Cardio Affect Muscle Growth? We broke down how cardio can help or hinder muscle growth depending on volume, timing, and intensity.

This is a very similar discussion, with the same outcome:

“Keep the goal, the goal - Dan John”

🔄 A Smarter Setup

If you want to train both hard, but equally, we recommend:

Splitting sessions (AM/PM)
Alternating days (weights one day, cardio the next)
Using low-impact cardio (e.g. bike) to reduce recovery cost

Even something as simple as finishing with a sled push or interval bike work can build aerobic capacity without harming strength gains.

🧬 What About Fat Loss?

Great question. While fat loss is mainly a nutrition game, the order still matters.

Lifting first protects muscle
Cardio after continues the calorie burn without compromising form
You stay stronger, leaner, and better recovered in the long run

Final Thoughts

Whether you do cardio or weights first should come down to one thing: your main training goal.

Weights first if you want to build muscle, strength, or retain lean mass during fat loss.
Cardio first if you're training for performance or aerobic improvement.

And if you’re ever unsure, we’re here to help.

Click here to apply!

References:

Robineau, J., et al. (2016). Effects of concurrent training sequence on VO2max and lower limb strength. Journal of Sports Science and Medicine, 15(2), 284-292.
Sporer, B. C., & Wenger, H. A. (2003). Effects of aerobic exercise on strength performance following various periods of recovery. Journal of Strength and Conditioning Research, 17(4), 638-644.
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.