Enhancing Running Performance: The Crucial Role of Muscular Endurance

## Redefining Endurance: The Shift Toward Muscular Strength Runners often focus on enhancing their aerobic capacity, striving to increase metrics like **VO₂ max** and **lactate threshold**. While these measures are cornerstones in the training regimens of many athletes, they're only part of the story when it comes to successful long-distance running. Scott Johnston, a coach with a track record preparing athletes for ultramarathons—think of champions like **Tom Evans** and **Ruth Croft**, winners of the 2025 Ultra-Trail du Mont-Blanc—takes a different approach. He prioritizes a lesser-well-known but critical aspect of performance: muscular endurance. Johnston challenges the conventional wisdom that emphasizes speed at the beginning of a race. Instead, he believes the key lies in sustaining performance when fatigue sets in after the early adrenaline has worn off. His training philosophy centers on the idea that enhanced muscular endurance translates into better performance. Johnston identifies muscular endurance as the ability of muscles to repeatedly exert force over a prolonged period. This characteristic is essential not just for elite athletes but for anyone looking to improve their running capabilities, whether you're tackling a 5K or gearing up for a marathon. “The goal of any endurance athlete is to **improve fatigue resistance**—because fatigue is what makes you slow down,” Johnston emphasizes. He’s recognized through extensive experience that while threshold training and **VO₂ max workouts** are effective tools for building resistance to fatigue, the secret weapon is muscular endurance training. ### The Underestimated Power of Muscular Endurance Understanding the mechanics of muscle fibers can provide insight into why muscular endurance is crucial. Johnston describes these fibers along a spectrum, from slow-twitch fibers, ideal for sustained aerobic activities, to fast-twitch fibers that fuel explosive power for short bursts. Between them lie **type IIa fibers**, or “frontier fibers,” which possess unique adaptive capabilities. These fibers fatigue faster than slow-twitch fibers but can still be trained to exhibit endurance characteristics. While traditional endurance workouts, such as **lactate threshold training** and **high-intensity interval training (HIIT)**, can engage these frontier fibers, Johnston points out that they often lead to whole-body fatigue, resulting from excessive lactate accumulation. This limits the cardiovascular benefits that can be gained from high-intensity training and hinders subsequent workouts. This revelation prompted Johnston to ask a pivotal question: Is it possible to strengthen these frontier fibers without pushing the cardiovascular system to its limits? The answer lies in approaching training with a focus on muscular endurance. By dialing down the intensity and targeting the specific muscles employed during running, athletes can build endurance without succumbing to total fatigue. Johnston's approach allows athletes to prepare their muscles for the challenges of both speed and distance. Once these endurance qualities are established, athletes can return to more traditional interval training with a significantly enhanced muscular capacity, ready to tackle rigorous cardiovascular workouts with greater efficiency. For anyone in the endurance running community, applying this knowledge is essential. The results from muscular endurance training can be profound, manifesting as improved stamina late in races or during long training runs. Johnston advises integrating these workouts thoughtfully into your training routine—once a week, framed by recovery days to allow for regeneration. This ensures that the body absorbs the training stimulus without being overwhelmed. By prioritizing muscular endurance, runners can not only prepare for immediate challenges but also cultivate lasting benefits that enhance their long-term performance and resilience.

Your Guide to Muscular Endurance Improvement

When it comes to enhancing muscular endurance, the focus isn’t about going all out and exhausting yourself. Rather, it's about strategically applying enough stress to your muscles to make them more resistant to fatigue. As Johnston emphasizes, the exercises you'll perform in the gym closely resemble the biomechanics of running, thus targeting the very muscles you'll rely on when hitting the pavement. By training these areas, you prime your body for both the demands of endurance events and general fitness. So, how do you translate this into an effective workout routine? Start with a solid plan.

Workout Breakdown

Begin with a 10-minute warm-up jog. Slow and easy—your goal is just to get the blood flowing and muscles prepped for the work ahead. Next, shift gears into a series of interval training exercises. For instance, the StairMaster is a great tool, as it forces you into an incline that simulates the terrain of trail running. Aim for six 5-minute intervals, maintaining a Rate of Perceived Exertion (RPE) of 3 to 4 while carrying 10 to 15% of your body weight. This could also mean brisk walking up a steep hill with a weighted backpack if that’s more suitable for your environment. Rest for a minute between intervals, focusing on working hard enough to feel a burn in your legs—this fatigue indicates that you're pushing yourself adequately. The workout should wrap up with a 10-minute cooldown jog to gradually return your heart rate to a resting state.

Progression and Adaptations

Once you've developed a base level of stamina, consider progressing the intensity of your workouts. Instead of simply increasing reps, extend the duration of each interval. For example, you can shift from 5 x 6-minute intervals to longer sessions such as 2 x 15-minute intervals, or even aim for a continuous 30-minute effort. This workout isn’t just for seasoned athletes. It’s tailored for beginners, making it an excellent starting point for those venturing into muscular endurance training. If you're experienced and looking for more challenge, Johnston has designed a comprehensive 14-week progression plan that incorporates additional exercises and gradually increases weight and repetitions. Ultimately, the intent of this regimen is clear: build resilience within your muscles and enhance your overall endurance for when it counts. If you're serious about elevating your performance in running—or any endurance sport—you'll find that this methodology offers a solid path forward.