Is your gym workout secretly hurting your running performance?

A research study on marathon runners showed that adding strength workouts will not prevent injuries if you ignore the total work your body handles. To build true strength without breaking down, you must count your gym sessions as part of your overall training load instead of just an extra task on top of your miles.

The trap of unmonitored total stress

Picture this: you are training for your next big race in Rutherford County and running along the Stones River Greenway every weekend. To protect your joints, you decide to add heavy leg workouts at the gym three days a week.

Lifting heavy and running on the same days is actually a great strategy that helps keep your hard days hard and your easy days easy. But problems start when you do not track the combined stress placed on your body.

Instead of feeling stronger, your knees start aching, and a familiar discomfort settles into your heels. Runners naturally have a performance-driven "push through" mentality, but your body views the strain of heavy squats and long runs together as one total training load.

What the science actually shows

A randomized study led by Dr. Brett Toresdahl (A Randomized Study of a Strength Training Program to Prevent Injuries in Runners of the New York City Marathon, PMID: 31642726) followed over 700 runners to see if adding a targeted strength program prevented running injuries.

The surprising result? Simply adding strength work on top of high running miles did not reduce injury rates.

When you add heavy gym workouts without adjusting your running volume, your total physical work spikes sharply. To protect your tissues, you must account for the total mechanical stress your body handles every week.

The physical therapy perspective

How to resolve, reload, and reinforce your training

While working with a physical therapist who can adapt and educate you on how to manage your load and mitigate issues that occur, not everyone is ready to commit to that level of care.

Here’s how you can apply Proactice Kinetic’s 3-step method to your own schedule right now:

• Resolve: Stop managing symptoms with ice or temporary rest. Audit your training log to see where your total work suddenly spiked, and look at how your body moves during your heaviest lifting or running days.

• Reload: Take responsibility for your physical preparation. Progressively reload your tissues by adjusting your weights and running volume so your body adapts to stress instead of breaking down.

• Reinforce: Play the long game by thinking in years, not weeks. Build sustainable movement habits that protect your body, keeping movement joyful and under your control for decades to come.

The run coach's advice

Practical takeaways for your next training week

Here is how you can balance your strength sessions and running miles this week:

• Consider your workouts each week holistically: Lifting and running heavy on the same day works well if you separate the sessions by a few hours. If you’re time constrained and trying to make the most of a single session, consider doing lighter runs paired with heavy lower body lifts. Alternatively, you can do hard, intense runs followed by lighter load strength training. Look at your week’s workouts as a whole instead of day-by-day to prevent overloading your body and creating an opportunity for injury.

• Count gym stress as running stress: Treat your heavy leg days as hard workout days on your calendar, not extra rest-day activities.

• Match your strength to your miles: When your running mileage peaks, dial back the weight or rep volume in the gym to keep total stress steady.

• Focus on movement habits: Remember that building a resilient body is about smart, consistent habits over time rather than constant intensity. If you are not moving all day and then going into an intense workout, you are increasing your risk for injury. Find opportunities to run, walk, or do basic strength exercises throughout the day to reduce your injury potential during hard workouts.

Ready to move with confidence?

You do not have to guess how to balance your strength work and running. If you are dealing with persistent discomfort or want to optimize your performance, the team at Proactive Kinetics would love to talk to you.

Disclaimer: Content published by Murfreesboro Run Collective is for educational, performance, and coaching purposes only. It does not constitute formal medical diagnosis or physical therapy treatment under a clinical Plan of Care. For individual injury evaluation, visit Proactive Kinetics.