Cardio for Lifters: How to Run Without Losing Gains

The Interference Effect

In the 1980s, studies suggested that cardio blocked the signals for muscle growth(mTOR vs AMPK).

Modern Update: It's not that black and white. It mainly affects power output more than hypertrophy, and usually only at high volumes.

Rules for Concurrent Training

1. Separate Sessions: Ideally, lift in the AM and run in the PM(or vice versa).Give your body 6 hours to reset signals.
2. Prioritize: Do the most important thing first.Want muscle ? Lift first.Want a marathon time ? Run first.
3. Type Matters:

• HIIT(Sprinting): Simulates lifting(high impact, high force).More recovery cost, but preserves muscle type.
• LISS(Zone 2 Jogging): Low impact, keeps heart rate at 130 - 140bpm.Creates very little systemic fatigue. This is best for most lifters.

Cardio and Appetite

Cardio isn't just for burning calories; it's a metabolic primer .

Zone 2 work has been shown to increase insulin sensitivity, meaning your post - workout carbs are more likely to go into your muscles rather than your fat cells.

However, beware of "Low Intensity hunger spikes." If walking for 2 hours makes you eat 1,000 extra calories, your cardio is hurting your cut.Use RepLog's diet notes to track this correlation.

Why You Should Do Cardio

• work Capacity: A better aerobic engine helps you recover between sets .If you are gasping for air after a set of 5 squats, your cardio is limiting your leg gains.
• Health: You can't flex a clogged artery.

Implementation

Two to three 30 - minute sessions of Zone 2 cardio per week will have zero negative impact on gains and will likely improve your lifting recovery.

Best Cardio for Lifters

1. Incline Walking: Low impact.Zero eccentric load(doesn't beat up legs). Best for fat loss.
2. Rucking: Walking with a weighted vest.builds traps, core, and glutes.
3. Sled Pushes: The only "concentric-only" cardio.Zero soreness.Great for conditioning.
4. Assault Bike: Brutal, but no impact on joints.

The Timing Protocol

• Best: Cardio on rest days.
• Good: Lift AM, Cardio PM(6 hours apart).
• Okay: Lift, then immediately do cardio.
• Worst: Cardio tailored, then Lift. (You will be pre - fatigued).

Sample Protocols

Option A: The Busy Dad(Zone 2)

• When: 6:00 AM(Before kids wake up).
• What: 30 mins incline walk on treadmill.
• Result: pure fat oxidation, zero impact on 6:00 PM lift.

Option B: The Athlete(HIIT)

• When: Immediately post - lift.
• What: 10 mins Assault Bike(10s Sprint, 50s Cruise).
• Result: Metabolic conditioning, high EPOC(afterburn).