Should Runners Strength Train on Hard Run or Easy Days? A Physical Therapist’s Take

A common question runners training for half or full marathons, especially those incorporating speed work and long runs, is: “Should I strength train on hard run days or easy days?”. 

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This is an excellent question. You want your hard efforts to pay off when you line up at the start line. You want strength workouts to complement your running, not leave you too fatigued to hit your paces and complete your runs effectively. 

Personally, I’ve had to experiment to find what works best for me. For a long time I would strength train right after my hard speed workouts. I found myself feeling so fatigued during and after that I knew I wasn’t getting a quality session in. Now I lift at least three hours after a speed workout one day and after an easy run the other day. I never lift heavy after a long run. That is just too stressful on the body. 

As a running coach, I have programmed strength training with what fits my runners’ schedules because doing it–even at suboptimal times–is usually better than not at all. But when should a runner lift weights for the best results? I took this question to Dr. Holly Richard, doctor of physical therapy, founder of Stronger Runners and my partner in creating the run + strength plans in the Stronger Runners app. She shares her insights for you below. 

The Best Timing for Strength Training for Runners

As a physical therapist, my recommendation for most recreational runners—those balancing work, training, and daily life—is to schedule strength workouts after an easy run. This strategy keeps you consistent, reduces the risk of overloading your body, and ensures you don’t skip strength training altogether.

That said, there’s no one-size-fits-all answer. Strength training enhances running economy, reduces injury risk, and improves performance, but the optimal timing depends on your mileage, training intensity, recovery needs, and schedule.

Some runners may thrive by stacking hard efforts, but most runners perform better when they spread out the workload. The key is finding what works for you.

The Case for Hard Days: Why Some Say “Stack the Stress”

You’ve probably heard the saying: “Make hard days hard.”  This philosophy suggests concentrating your toughest efforts into fewer key sessions. The logic is simple: if you’re already pushing your body with high-intensity intervals, tempo runs, or long miles, why not add strength training to maximize the challenge? Then, you can recover fully on lighter days.

There’s some science behind this approach. A 2012 meta-analysis in the Journal of Strength and Conditioning Research (Wilson et al.) found that combining strength and high-intensity endurance training in the same day can enhance adaptations—if recovery is prioritized afterward. The idea is that stacking stress signals your body to adapt more efficiently, improving both muscle power and aerobic capacity.

However, timing matters. A 2021 Sports Medicine study found that waiting at least 3–6 hours between endurance and strength sessions led to better adaptations than doing them back-to-back. Longer recovery periods (>6 hours) were even more beneficial.

Who Benefits from the “Hard Days Hard” Approach?

This strategy works best for runners who have the flexibility to space out their workouts—running in the morning and strength training in the afternoon or evening. It may be particularly useful for:

✅ Shorter-distance runners (5K/10K) focusing on power and speed.
✅ Athletes with high recovery capacity who adapt well to heavy training loads.
✅ Competitive runners who can plan dedicated recovery blocks after intense training days.

Is It Right for You?

Here’s the catch: Hard days are already demanding. 

Adding a strength workout after a tough speed session or a 15-mile long run or a can leave your legs feeling like lead so you are not being able to push yourself in your strength workout. Plus, if fatigue and soreness lingers into your next run, it can affect your pace, form, and overall performance.

For busy recreational runners—especially those balancing work, family, and long-distance training—the “hard days hard” method may not be practical. Overloading too much in one day can increase injury risk and lead to burnout if recovery isn’t sufficient.

If you’re considering the “hard days hard” approach, ask yourself if you can space out your workouts by at least a few hours and if you recover well between sessions. If the answer is yes, it may be worth experimenting. No? The “strength after an easy run” strategy may be a better fit.

The Case for Easy Days: Spread the Stress

Now, let’s consider the opposite approach: strength training after easy run days. These shorter, conversational-pace runs are meant for active recovery, so why not pair them with strength training?

Why Strength Training on Easy Days Works

A 2014 review in Sports Medicine (Fyfe et al.) found that strength training after lower-intensity aerobic exercise—like an easy run—minimizes interference with endurance adaptations. Your easy run warms up your muscles, boosts circulation, and leaves you ready to lift without compromising tomorrow’s run. It’s a win-win: you build strength without overloading your system.

Practical and Sustainable

Easy days are meant for recovery, but they’re not complete rest days. Combining an easy run with a strength session keeps your overall effort moderate and manageable. You’re not stacking stress—you’re spreading it out.

This aligns with what I see in my practice: runners who stay consistent and injury-free don’t overload their hard days. Instead, they seamlessly fit strength training into their routine, providing the right effort without burning out.

The Bottom Line: Strength Training on Easy Days are the Way to Go (For Most Runners)

As a physical therapist, I highly recommend that most runners combine easy runs with strength workouts. This strategy supports key areas like performance, injury prevention, and consistency. It builds strength without compromising important runs, reduces strain on fatigued legs by spreading the workload, and integrates smoothly into your routine, ultimately leading to better long-term results.

If you’ve struggled with consistency or having the energy for strength workouts, try adding strength training after your easy runs and observe how your body responds.

 

The run + strength plans Holly and I created in the Stronger Runners app can also help you balance your running with lifting. It combines strength training with my free run plans so you can take the guesswork out of how to do both. Sign up for only $22 a month. Have you struggled with how to balance the stress of lifting weights with running?