Improve Endurance & Stamina Performance Through Strength Training

As an endurance athlete, you’ve been told that strength training can help improve your performance, but is that the case?
Athletes since the beginning of sport have been using some form of strength training to improve athletic performance, but leveraging the benefits of these training methods to improve endurance is easier said than done.
To achieve this, you’ll need to have a solid plan that ensures you’re making the correct choices with your training to improve performance.

Strength Training Can Ruin EnduranceImprove Endurance & Stamina Performance with Strength Training

Before moving any further, you need to know that if misused, strength training can ruin your endurance performance. In fact, scientists even use the term interference to describe how using these two training methods simultaneously often make progress difficult for the athlete. 

Aptly named, the interference effect describes how strength training and endurance training promote different changes in the body. When you attempt to build strength and endurance simultaneously, the body has difficulty handling both, which often reduces the effectiveness of the training program (1, 2).
Exercise, regardless of form, results in some change in the body in the way of an adaptation. Most of us think of training just as another daily task, but to the body, exercise is stressful and somewhat threatening. So the body responds to it by making you stronger, more fatigue resistant, or both depending on the type of training you employ. 
When you strength train using heavy resistance, the body responds by making your muscles bigger and stronger. It also changes how your brain tells your muscles to contract, so they do so with more force, helping you overcome the inertia of heavier objects.
Endurance adaptations, however, are in stark contrast to that of strength training. For endurance performance, your muscles have to contract with low force, but for a long time while also removing metabolic byproducts of muscle contraction with high efficiency. 
Mostly, strength training promotes an increase in muscle size and force production, while endurance promotes smaller muscle size, a better ability to use oxygen for energy production and the ability for your muscles to contract with low force, for an extended period.
As you can imagine, the need for optimizing both attributes is important to an athlete, yet, challenging to achieve. But with the right steps and considerations, resistance training can indeed help improve the endurance athlete's performance.
Summary: The adaptations from strength and endurance training differ, resulting in interference. Circumventing this interference as an athlete is a goal when attempting to use resistance and endurance training simultaneously.

What Matters For Endurance?

Improve Endurance & Stamina Performance with Strength Training

If you're hoping to use resistance to improve your endurance performance, you need to first consider what variables are most important to develop and second, how resistance training can help you make those improvements.
In terms of endurance performance, there are three important variables to consider:
  1. Muscle Fiber Composition & Their Function
  2. Removal of Metabolic Byproducts of Muscle Contraction
  3. Better Use Of Oxygen & More Mitochondria.

Our muscles include thousands, if not millions of individual muscles fibers, which all contain the components that allow for muscle contraction. These fibers are categorized mostly based on their size, function and preferred energy source.  For instance, Type I fibers are considered endurance fibers due to low-intensity contraction and fatigue resistance while Type II fibers are beneficial for strength, contracting forcefully for short amounts of time (3, 4).

As an endurance athlete, improving the performance of Type I fibers is explicitly the goal, since these fibers provide attributes needed for endurance performance.
Improve Endurance & Stamina Performance with Strength Training
During exercise, as our muscles contract, the usage of different energy sources results in the accumulation of substances like lactate and hydrogen, which cause discomfort and impede muscle contraction. Thus, being able to remove these metabolites will allow your muscles to contract more forcefully and for longer durations (5).
Endurance also requires that your muscles use oxygen efficiently over time to generate a constant stream of energy. This benefit is achieved through improving the muscle's ability to use oxygen but also by increasing the number and efficiency of organelles in our muscles called mitochondria. These mitochondria use oxygen to metabolize fat molecules for energy, which is the preferred energy source of the body during endurance events (6).
By breaking down your training needs in this manner, you can begin to pinpoint your exact needs as an endurance athlete and then determine how resistance training can better help you improve these variables.
Making logical and rational adjustments that will improve your performance is only possible when you understand what you need to improve and why.
Summary: Just using resistance alone won't improve performance. Instead, consider what variables you need to improve and how strength training can help you.

Specificity Matters

Improve Endurance & Stamina Performance with Strength Training

When using strength training to improve your endurance performance, how you perform these workouts will determine if you improve or make no progress at all.
To improve endurance, being able to resist fatigue and continue performing at a high level is essential. Achieving this relies heavily on the specific type of exercise you expose your muscles too.
In a groundbreaking study, Dr. Brad Schoenfeld and his colleagues revealed that regardless of the amount of resistance you use, muscle growth could occur. This means that no matter if you use heavy or light resistance, you can still increase the size of your muscles (7).
An arguably more significant finding, however, is that the function of those muscle gains does depend on the amount of resistance you're using (7, 8)
For instance, using heavier weight often results in fewer repetitions. But if you approach failure during sets, this should stimulate growth in the muscle. As this happens though, you've been teaching the muscle to contract forcefully for a short duration to overcome the heavier resistance. As a result, the function of your muscles will be beneficial for strength production.
Alternatively, let’s say you use a light amount of resistance, but complete many repetitions, approaching failure. Here, the size gains of your muscles should be similar to that of the heavy resistance. However, the function of these muscles will be more beneficial for higher repetition sets and fatigue resistance (7, 8).
As an example, many runners squat heavy in the gym because they've been told that squatting and squatting heavy will improve running performance. But based on the variables mentioned above, will it?
The reality is that it probably won't. In this same example, however, squatting with a lighter weight and high repetition range likely will provide a benefit because it will help strengthen muscles but also induce fatigue resistance and byproduct clearance.
Importantly, other research specifically on this topic corroborates these findings.
In one study, female cyclists were exposed to an 11-week, progressive resistance training program, meaning they progressively increased resistance reduced repetitions. The results showed that these women observed little to no benefit, specifically for endurance performance, but did get stronger. So while there was indeed benefit, it wasn’t the benefit that the endurance athlete needed. Had the resistance program been focused on improving endurance attributes instead, the findings would likely have been different (9).
To clarify, this doesn't mean that you should never train heavy again, as heavy resistance training strengthens muscles and bones, which benefits everyone. Instead, ensure that the majority of your resistance training is in line with your specific needs. Otherwise, you'll see no benefit.
Summary: When using resistance, use training specifically for the performance attributes you want to improve. As an endurance athlete, focusing on higher repetition sets often will be more conducive to endurance improvement than heavier, lower-repetition sets.

Use A Periodized Program

Improve Endurance & Stamina Performance with Strength Training

 Using strength training to bolster endurance performance is a difficult task to master but using a periodized approach can make the process easier and arguably more useful. For example, an endurance athlete can use a periodized program to use both heavy and light resistance training appropriately to improve performance (10).

The term periodization is merely a term to describe how this process works. Throughout a pre-determined duration, such as three months, you can program your training based on "periods" or "blocks" of time, that have different training goals.
Let's say you have an endurance event coming up, so you decide to build a 3-month training program including resistance and endurance exercise. How would you create it?
First, you could separate this 3-month program into three distinct periods or blocks, each lasting one month.
In this specific example, block one would include a mixture of resistance and endurance, with an emphasis on strength. Since this block is the furthest away from the event, you can be less specific in your training needs. This also allows you to specifically focus on improving the strength and resilience of your muscles but then focus more on endurance particular needs as you approach the event.
In block two, you can reduce resistance and increase endurance specific training, creating a more balanced approach.
Finally, in block 3, you can then reduce resistance training significantly, replacing it with endurance specific training. This ensures that you're focusing specifically on the variables required for performance during the event while avoiding unnecessary extras.
As you can see with this approach, the beginning of the training program is vast, with different focuses. But as the event approaches, training is funneled towards the specific requirements of the event. In this example, the funnel pushes you towards endurance-specific training, which will specifically provide the benefits needed for endurance performance.
Summary: Periodization is a method to help you funnel your training program from broad to specific as your event approaches. This enables you to use the benefits of different types of training in a way that improves performance.

Prioritizing Exercises & Muscle Groups

Improve Endurance & Stamina Performance with Strength Training

When attempting to use weight training to improve endurance, I recommend that you try to focus on the essential muscle groups and exercises that will directly improve endurance performance.  
Mostly, this means that you should only be using exercises and training muscle groups if you know doing so will improve some aspect of your performance, while removing those that do not. This ensures you’re making the progress you need while avoiding exercises that won't help you. 
A great idea is to use a periodized approach to funnel the exercises you're using and the muscle groups you're training. For instance, in block one, you can perform exercises like biceps curls and even deadlifts since specificity is not as important. But as you approach blocks 2 and 3, you can funnel the exercises you’re using to become as specific as possible.
Summary: Prioritize the muscle groups and exercises that will benefit your specific performance needs. Anything extra can impede your ability to recover while not providing the benefits you need.

Recovery & Nutritional Considerations

Improve Endurance & Stamina Performance with Strength Training
As an athlete using different forms of training, recovery can be difficult. Having a plan and avoiding common pitfalls can help make things easier.

Eat Enough

It goes without saying that for the athlete, eating to perform and recover is essential. A good starting point is to eat around your maintenance calories to start. This is the number of calories you can eat each day while neither gaining nor losing weight. While doing so, ensure that you're eating enough protein and carbs, and maintaining a healthy fat intake
From there, evaluate your ability to recover. If you’re performing well and able to recover, then your nutrition might be perfect. If you're sore, injured, and continuously tired, that's a good sign you're not eating enough food.
Just remember that you need to eat enough food for recovery but also that your nutritional requirements are dynamic and may change throughout your program. I suggest you regularly reevaluate your needs based on performance and how you feel.

Don’t Be Afraid To Rest

Many people, especially serious athletes, have an all or nothing mentality. We feel guilty when we miss a workout for any reason. But the reality is that sometimes, it’s good to take a day off or dial things back when we need it, even if it feels like the wrong thing to do.
Remember that taking rest is when the body adapts and improves. If you feel you need extra rest, there are few reasons not to do so. Indeed, you'll need to fight through fatigue and pain, as any athlete does but recognizing when it's ok to take extra rest can benefit your performance.

Anecdotal Experience With Resistance & Endurance

Improve Endurance & Stamina Performance with Strength Training 
One of the reasons this topic is of interest to me is because I've lived it. This past year, I transitioned from being a powerlifter to a marathoner, and I used every piece of information in this article to do it successfully. Here’s what I did.

I Started Running A Lot

Exercise performance demands specificity, so I began running as often as possible. I did this first to improve my ability to run or my running economy, while also enhancing my cardiovascular ability. Just as with resistance exercise, to improve my running ability, I needed to get better at the movements associated with running specifically.
Regardless of the event, you're participating in, just getting started is usually the best first step.

I Reduced Resistance Training

When I added endurance training into the mix, something had to give, and since heavy resistance training was less specific to my needs, this type of training was the first to go. At first, I only reduced how much I was doing per workout. But under a periodization model, the variety of exercises I used was tapered as the marathon approached to make way for additional running workouts.
By reducing exercise variety and resistance training volume, I used only exercises I felt would benefit running performance while allowing for additional endurance training and recovery.

I Focused On Higher Rep Ranges

After nearly a decade of heavy resistance training, improving strength and muscle size wasn't relevant. Instead, I needed to focus on increasing fatigue resistance, removing metabolic byproducts and enhancing the ability of my muscles to contract for long durations. 
As the marathon approached, I made sure that the exercises I used were completed for high repetitions sets to match the demands of running at a faster pace more closely. Since heavier resistance wouldn't provide much performance benefit, I removed it from my program. 
Training with higher rep ranges more closely matched my needs during the marathon, so that became the priority.

I Hired A Mobility Coach

As an athlete training hard, you’re going to experience pain, discomfort, and even injury but a mobility coach might help. During my training, I began to develop overuse injuries and pain, so I hired a coach to help guide me to better movement and flexibility.

By working on mobility with someone that had more expertise, my running economy improved, my overall pain was reduced, and I potentially avoided additional injury. As a result, I felt good while running and performed better during the event.

The Results

I finished the race! But really, I didn't just finish it; I felt amazing and performed better than I could have imagined. During the race, I felt confident in my ability and also felt powerful and able to run at a good pace throughout. I felt, in particular, that focusing on higher repetitions with resistance helped improve my fatigue resistance and ability to remove metabolites during the race.

What did happen, however, was a marked reduction in my strength ability. While unfortunate and saddening to me, this was a reality that is to be expected. My training involved endurance running and high repetition resistance workouts while avoiding heavy resistance training, so a loss of strength was to be expected.
I also lost a considerable amount of body weight during this process, which alludes to the fact that I didn't eat enough. Fortunately, this lack of food didn't impede recovery as much as expected, but it's still something that should be considered.

Bringing It All Together

Improve Endurance & Stamina Performance with Strength Training

As an endurance athlete, there are many factors to consider in your training and using resistance might be one of them.
The reality is that resistance training can improve or hurt your endurance performance, depending on how you use it. The specific ways you use resistance will, of course, determine which effect you experience.
Importantly, remember that strength training can interfere with your endurance performance, but only if you're using it in ways that don't benefit your performance. As a good example, squatting heavy probably won't help you, but squatting lightweight for many repetitions might.
Making these specific distinctions in your training will help ensure that your resistance training provides the benefits you want and need.

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  2. Murach, K. A., & Bagley, J. R. (2016). Skeletal muscle hypertrophy with concurrent exercise training: contrary evidence for an interference effect. Sports medicine46(8), 1029-1039.
  3. Proctor, D. N., Sinning, W. E., Walro, J. M., Sieck, G. C., & Lemon, P. W. (1995). Oxidative capacity of human muscle fiber types: effects of age and training status. Journal of applied physiology78(6), 2033-2038.
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  2. Schoenfeld, B. J., Contreras, B., Vigotsky, A. D., & Peterson, M. (2016). Differential Effects of Heavy Versus Moderate Loads on Measures of Strength and Hypertrophy in Resistance-Trained Men. Journal of sports science & medicine, 15(4), 715.
  3. Vikmoen, O., Raastad, T., Seynnes, O., Bergstrøm, K., Ellefsen, S., & Rønnestad, B. R. (2016). Effects of heavy strength training on running performance and determinants of running performance in female endurance athletes. PloS one11(3), e0150799.
  4. Plisk, S. S., & Stone, M. H. (2003). Periodization strategies. Strength & Conditioning Journal25(6), 19-37.

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