The Old Fear: The Interference Effect
The long-standing belief among many fitness enthusiasts was that aerobic exercise, or cardio, could sabotage muscle and strength gains. This idea, known as the "interference effect," originated from research in the 1980s. The theory suggested that the physiological
signals sent by endurance training could cancel out or dampen the signals for muscle growth stimulated by resistance training. This led many to separate their cardio and strength workouts by days, or even avoid significant cardio altogether, fearing it would undo their hard work in the weight room.
New Studies Challenge Old Beliefs
Recent scientific reviews and large-scale studies are painting a much different picture. A semi-systematic review from early 2026 concluded that for most people, concurrent training does not negatively impact gains in muscle size or maximal strength, regardless of whether you lift first or do cardio first. Another major study published in the British Journal of Sports Medicine, which followed over 147,000 adults for decades, found that combining aerobic exercise and strength training delivered the strongest survival benefits and a lower risk of death from all causes.
More Than Just Compatible, It's Beneficial
The latest findings go a step further than just dispelling the interference myth. Research from Iowa State University published in the European Heart Journal showed that a workout plan split evenly between aerobic and resistance exercise reduces cardiovascular disease risk just as much as an aerobic-only plan. This means you don't have to choose between heart health and muscle strength—you can effectively train for both simultaneously. In fact, an umbrella review of multiple meta-analyses in early 2026 confirmed that concurrent training improves aerobic capacity significantly compared to resistance training alone, while achieving comparable results in strength and muscle growth. It's a win-win.
Does the Order of Your Workout Matter?
So, if you’re doing both in one session, what should come first? The science here offers some nuance. For goals related to maximal strength and muscle growth, most research suggests a slight advantage to performing strength training before cardio. However, for general fitness, endurance, and overall health, the sequence doesn't seem to make a significant difference. The most important factor is consistency. The best workout plan is the one you can stick with. If your primary goal is to improve your running, doing cardio first while you're fresh makes sense. If your focus is building raw strength, hitting the weights first is likely your best bet.
Putting It All Together: Your Weekly Plan
Based on the latest evidence, a balanced routine is key. A study highlighted a sweet spot of 90 to 120 minutes of resistance training per week for longevity benefits. When combined with the recommended 150 minutes of moderate aerobic activity, the health outcomes were even greater. You can achieve this by doing a few full-body strength sessions a week and complementing them with cardio. This could mean lifting weights before going for a run on the same day or alternating between dedicated strength and cardio days. The research shows that as long as you allow for adequate recovery, combining these activities is not only safe but optimal for long-term health and fitness.
