Strength training can reduce injury and improve endurance without packing on muscle mass
For endurance runners—whether you're running a few miles, a marathon, or something in between—resistance training (RT) has become an essential yet often misunderstood part of training. Traditionally associated with bulk and brute power, RT is something many runners still avoid. However, recent studies, including a recent publication in Sports Medicine, highlights that RT, when approached correctly, can significantly benefit endurance athletes by improving running economy, reducing injury risk, and even boosting race performance. The key lies in structuring RT to complement, rather than compromise, endurance gains.
As a muscle physiologist and endurance runner, I've always been fascinated by the adaptability of our muscle systems. Muscle composition—particularly the balance between slow-twitch and fast-twitch fibers—plays a pivotal role in shaping how our bodies respond to different training regimens. Personally, I began my athletic journey with a focus on power and strength but gradually shifted toward long-distance running. While I haven’t recently confirmed my muscle composition with a biopsy (though I have analyzed many others!), my sense is that my muscle profile has evolved over the years, skewing toward slow-twitch dominance to support endurance over explosive power. Regardless of this shift, resistance training has remained a critical part of my regimen—not for bulking, but to protect against the wear and tear of high mileage, improve running mechanics, and to gain a performance edge.
The Case for Resistance Training in Running
The perception of RT as purely a muscle-building endeavor has lingered in the running community for years. However, when implemented thoughtfully, RT can strengthen essential muscle groups, enhance neuromuscular coordination, and improve resilience against the repetitive stress of distance running. Recent studies underscore that low-volume, high-load RT, tailored for endurance needs, can help runners avoid “bulking up” and instead bolster their running efficiency.
This tailored approach taps into neuromuscular adaptations and tendon reinforcement—key factors that can improve stride economy, support joint stability, and reduce impact forces on the body. Effective RT supports running mechanics by strengthening key muscles that stabilize the hips, glutes, and core, contributing to a smoother and more efficient stride. This helps runners maintain form and alignment, reducing compensatory movements that could lead to injury. Importantly, RT focuses on building strength and stability in a way that enhances rather than hinders an athlete’s endurance capabilities—net positive.
(Photo: Illustration, Sports Medicine)
Getting to Know Your Muscle Fiber Types
An often-overlooked aspect of effective training lies in understanding muscle fiber types—slow-twitch and fast-twitch—each influencing performance in unique ways. Most people have a mix of both types, though the ratio varies and can shape the effectiveness of different training styles. Slow-twitch fibers are highly resistant to fatigue, making them ideal for sustained, marathon-style efforts. Conversely, fast-twitch fibers produce more power but fatigue more quickly, a useful feature for sprinters or those aiming for a strong finishing kick.
Evidence suggests that adjusting resistance training to favor the type of fibers you want to develop can help optimize training without sacrificing efficiency. For instance, low-volume, high-load RT strengthens slow-twitch fibers without promoting excessive muscle hypertrophy, keeping endurance runners light and efficient. Since endurance athletes don’t rely on fast-twitch fibers as much as sprinters do, minimizing fatigue-inducing high-rep protocols, which often engage these fibers, can be beneficial.
Practical Applications for Resistance Training in Endurance Running
Endurance runners benefit most from RT programs tailored to their needs, focusing on strengthening without adding unnecessary bulk. Here’s a breakdown of practical RT strategies that can be effectively integrated into an endurance regimen:
1. Focus on Low-Volume, Heavy Load Training Without Reaching Failure
For endurance runners, low-volume, heavy-load RT (≥85% of 1-RM) strengthens muscles without significant hypertrophy. Training just short of failure is essential, as lifting to failure often induces more muscle growth than endurance athletes may want. Instead, lift weights you can manage for six reps but complete only four or five reps per set. This approach builds resilience with minimal size increase.
Guideline: Perform two to three sets of two to three exercises per session, keeping repetitions low and using weights at or above 85% 1-RM.
2. Prioritize Multi-Joint Exercises to Enhance Intermuscular Coordination
Exercises like squats, lunges, and deadlifts work multiple muscle groups simultaneously, supporting the muscles and joints involved in running. These movements mirror the weight-bearing demands of running, enhancing balance and reducing energy inefficiencies. This type of RT improves the “kinetic chain”—the series of connected movements that create each running stride, leading to better running mechanics and reduced risk of injury.
Recommended Exercises: Squats, deadlifts, lunges. Volume: Two to three sets per exercise, focusing on maintaining form and coordination.
3. Incorporate Ballistic and Plyometric Exercises to Boost Power Output
Ballistic and plyometric exercises (e.g., box jumps, jump squats) are short, explosive movements that enhance tendon elasticity and power without adding bulk. Adding one or two sets of these exercises can improve power output for hill climbs or that final sprint to the finish line.
Recommended Exercises: Box jumps, depth jumps, medicine ball throws. Volume: One to two sets of each exercise, performed at high intensity.
4. Explore Cluster-Set Training or Velocity-Based Training Techniques
Cluster sets, which incorporate short breaks within a set, allow for lifting heavier loads without fatigue. Velocity-based training (VBT) emphasizes maintaining movement speed even with heavy loads, maximizing neuromuscular benefits without tiring muscles. These methods avoid the fatigue that traditional high-rep protocols cause, allowing endurance athletes to prioritize strength.
Cluster-Set Example: Perform four reps, rest 10 to 20 seconds, then perform another four reps. VBT: Use a tracker to monitor bar speed, ensuring consistent lifting velocity.
5. Avoid High-Rep, Low-Load Training That Leads to Fatigue
High-rep, low-load training is often misunderstood as beneficial for endurance, but it fatigues the muscle’s low-threshold motor units without properly engaging high-threshold ones needed for strength. Instead, heavy loads with low reps build strength without risking muscle fatigue or excessive bulk.
Guideline: Use four to six reps per set with ≥85% 1-RM, stopping before muscle failure.
6. Leverage Periodized Training for Seasonal Adaptations
For anyone racing, periodized RT programs that adjust volume and intensity according to the training season can be highly effective. Use moderate volumes during the off-season to build a foundation of strength, tapering down to low-volume, high-load sessions closer to race day to maintain strength gains without sacrificing speed or endurance.
Structure Example: Begin with moderate-volume RT, transitioning to low-volume, high-load training as races approach.
Building Endurance on a Foundation of Strength
Understanding the science behind RT enables runners and endurance athletes to avoid the pitfalls of bulk and fatigue while embracing the benefits of strength, stability, and injury prevention. Low-volume, high-load RT, focused on heavy but non-fatiguing reps, provides runners with a boost in strength without compromising speed or stride efficiency. Integrating this strength foundation into an endurance regimen isn’t just a path to resilience; it’s a formula for sustained performance and injury prevention. For runners, strength training isn’t about “bulking up.” It’s about fine-tuning the muscle fibers—particularly slow-twitch types—to work efficiently and effectively for the long haul. With smart training, you can reap the benefits of strength without compromising your endurance, building a body that’s equipped to handle mile after mile while staying resilient and adaptable to any challenge the road—or the track—throws your way.