Muscular endurance—the ability to sustain repeated muscle contractions over time—is increasingly recognized as a cornerstone of athletic performance and functional fitness. While traditional strength training has long been associated with increases in maximal force production, recent research underscores that it also plays a crucial role in enhancing endurance performance and mitigating neuromuscular fatigue (Hammert et al., 2025; Zhang et al., 2025). For decades, athletes and coaches treated strength and endurance as largely separate qualities, often prioritizing one at the expense of the other. However, emerging evidence challenges this dichotomy, showing that strategically designed resistance training can improve not only absolute muscular endurance but also sport-specific performance determinants such as running economy, lactate threshold, and late-stage power output (Ramos-Campo et al., 2025). Functional resistance training—emphasizing compound, sport-specific movements—has proven particularly effective in simultaneously developing muscular strength and endurance, providing a transferable advantage to athletes in team sports and dynamic disciplines (Gürkan et al., 2025). Moreover, novel concepts like cross-education suggest that training one limb may confer endurance benefits to the untrained contralateral limb, opening new possibilities for injury rehabilitation and performance optimization (Song et al., 2024). Beyond pure performance, muscle mass itself has emerged as a critical determinant of fatigue resistance, with lean muscle contributing to metabolic efficiency, force sustainability, and injury prevention in endurance contexts (Zhang et al., 2025). This convergence of research signals a paradigm shift: muscular endurance, strength, and sport-specific performance are not mutually exclusive but deeply interconnected, emphasizing the need for integrated, evidence-based training strategies that maximize both power and persistence.

Clinical pearls

1 The Paradox of Strength and Repetitions

Scientific Perspective: Resistance training significantly increases absolute muscular endurance (repetitions at a fixed external load) via hypertrophic and neural adaptations. However, relative muscular endurance (repetitions at a specific % of 1RM) often remains stagnant or decreases, as the rate of maximal strength gain typically outpaces the rate of local metabolic adaptation.

Just because you can bench press 100 lbs for more reps than before doesn't mean your "stamina" has improved across the board. Since you got much stronger, 100 lbs is now a smaller percentage of your max. To truly improve your "gas tank" at higher intensities, you need to specifically practice high-rep sets (15–20+) rather than just chasing heavy weights.

2. The "Shield" of Muscle Mass

Scientific Perspective: Increased lean muscle mass serves as a reservoir for neuromuscular fatigue resistance. By increasing the available motor unit pool, the central nervous system can rotate "fresh" motor units into use as others fatigue (motor unit rotation), preserving power output and metabolic efficiency during prolonged submaximal efforts.

Think of muscle like the engine size in a car. A bigger engine doesn't have to work as hard to maintain 60 mph as a tiny engine does. By building a bit more muscle in your legs and core, you create a "backup system" that kicks in during the last mile of a race when your primary muscles start to give out.

3. Cross-Education and Symmetry

Scientific Perspective: Unilateral resistance training may induce bilateral adaptations in muscular endurance through "cross-education." This is likely mediated by spinal and supraspinal neural plasticity, suggesting that the "untrained" limb benefits from the neural drive generated by the "trained" limb.

If you have a cast on your left arm, don't stop training your right arm! Research shows that training one side of the body can actually send "signals" to the other side to keep it from losing too much fitness. It’s a great way to "cheat" your way through an injury recovery.

4. Running Economy and the "Spring" Effect

Scientific Perspective: Supplementing aerobic training with resistance work improves running economy (VO₂ at a given submaximal velocity) by increasing musculotendinous stiffness. This allows for better storage and release of elastic energy, reducing the active metabolic cost of each stride or pedal stroke.

Lifting weights makes your tendons and muscles act like high-quality pogo sticks. Instead of your legs "sinking" into the ground with every step, you "pop" back up more efficiently. This saves oxygen and energy, meaning you can run at the same speed with less effort.

5. The Functional Specificity Advantage

Scientific Perspective: Functional resistance training—utilizing multi-planar movements and stability demands—produces superior strength-endurance transfer in field athletes compared to sagittal-plane, machine-based training. This is due to the closer alignment of the training's mechanical and metabolic demands with the sport’s specific movement constraints.

If you play a sport like hockey or soccer, doing leg presses isn't enough. You need to do exercises that mimic the twists, turns, and balances of your game. "Functional" training hits your stabilizers and prime movers at the same time, making you strong in ways that actually show up on the scoreboard.

6. The Interference Effect Myth

Scientific Perspective: The "interference effect"—where strength training supposedly blunts aerobic adaptations—is largely mitigated when resistance training is performed at moderate intensities (60–75% 1RM) and separated from high-volume endurance sessions. Chronic interference is more a product of overtraining/recovery debt than a physiological impossibility of concurrent adaptation.

You don't have to choose between being "strong" and being "cardio-fit." As long as you aren't trying to break powerlifting records on the same day you run 15 miles, the two types of exercise actually help each other. Space your lifting and your running out, and you’ll likely see better results in both.

Understanding Muscular Endurance: A Fresh Look at Recent Research

Muscular endurance—the ability to sustain muscle contractions over repeated efforts—is a critical component of athletic performance and functional fitness. Yet for years, the science behind how we develop and measure muscular endurance has been fragmented across different research groups. Five groundbreaking studies published in 2024-2025 are now providing a clearer picture of how strength training, muscle mass, and endurance performance interconnect. Let's dive into what these studies reveal and why they matter for your training.

Mechanistic Insight:
Cross-education likely occurs through neural adaptations rather than direct muscular changes. Training one limb enhances motor cortex excitability and interhemispheric communication via the corpus callosum, improving voluntary activation of the untrained contralateral limb (Song et al., 2024). At the cellular level, endurance-focused training predominantly enhances mitochondrial density, capillary supply, and oxidative enzyme activity, improving fatigue resistance, whereas strength-focused training primarily induces muscle fiber hypertrophy and neural drive, increasing maximal force output (Hammert et al., 2025; Zhang et al., 2025). Understanding these distinct adaptations helps design programs that integrate both strength and endurance for optimal performance.

Study 1: Cross-Education of Muscular Endurance—A Scoping Review

One of the most intriguing phenomena in exercise science is cross-education—the improvement in strength or performance of an untrained limb after training the opposite limb. But what about muscular endurance? This scoping review by Song et al. (2024) examined whether cross-education of muscular endurance actually occurs and, if so, what mechanisms drive it.

The researchers synthesized existing literature to determine if training one arm or leg with high-repetition resistance training could enhance muscular endurance in the contralateral (opposite) side without direct training. Their work highlights a critical gap: while cross-education of strength is well-established, the cross-education of muscular endurance phenomenon remains largely unexplored and understudied.

Key Takeaway: Cross-education effects may transfer muscular endurance adaptations between limbs, but more research is needed to understand the neurological and physiological mechanisms. This suggests that unilateral training (training one side) might provide unexpected bilateral benefits for muscular endurance capacity.

Why This Matters: If cross-education of muscular endurance is confirmed through future research, it could revolutionize rehabilitation protocols for injured athletes. Imagine maintaining muscular endurance in an injured limb by training the uninjured side. This scoping review sets the foundation for such investigations.

Study 2: Changes in Absolute and Relative Muscular Endurance After Resistance Training

Changes in Absolute and Relative Muscular Endurance After Resistance Training: A Review of the Literature With Considerations for Future Research. Journal of Strength and Conditioning Research, 39(4), 474–491.

Here's a question that confuses many athletes: when you do strength training, does your muscular endurance improve? The answer, according to Hammert et al. (2025) is nuanced—and depends on how you measure it.

This comprehensive review distinguished between two critical concepts:

·Absolute muscular endurance: The total number of repetitions you can perform at a fixed weight (e.g., 50 kg)

·Relative muscular endurance: The number of reps you can perform at a percentage of your maximum strength (e.g., 70% of your 1-rep max)

The findings were striking. Resistance training consistently improved absolute muscular endurance—people could do more reps with the same weight. However, relative muscular endurance often remained unchanged or even decreased slightly, because their strength gains outpaced their muscular endurance adaptations.

Key Takeaway: Traditional strength training is excellent for building raw work capacity (absolute muscular endurance), but if your goal is improving relative muscular endurance, you may need higher-repetition, lower-load protocols. This distinction is crucial for periodization and training design.

Practical Application: If you're training for a sport requiring sustained effort at high intensities—like competitive CrossFit or rowing—incorporate dedicated muscular endurance blocks with moderate loads (50-70% of 1RM) and higher repetitions (15-30 reps). If your sport rewards pure strength, don't worry if your relative muscular endurance drops slightly.

Study 3: Functional Resistance Training and Strength-Endurance Adaptations in Elite Field Hockey(Hybrid Athlete / Hybrid Training}

What happens when you apply functional resistance training—exercises that mimic sport-specific movements—to elite young athletes? This study by Gürkan et al. (2025) provides fascinating insights.

Functional resistance training differs from traditional strength training in that it emphasizes compound movements, stability demands, and directional specificity. The research team trained elite field hockey players using sport-specific resistance protocols and measured both their muscular strength and muscular endurance.

The results demonstrated significant gains in both domains. Young elite athletes showed robust improvements in strength adaptations and sustained muscular endurance capacity, suggesting that functional resistance training effectively addresses both qualities simultaneously. This is particularly important because field hockey demands repeated high-intensity efforts with directional changes.

Key Takeaway: Functional resistance training that incorporates sport-specific movement patterns produces superior strength and endurance adaptations compared to generic resistance protocols. This approach develops sport-specific muscular endurance while maintaining strength gains.

Evidence-Based Takeaway: Elite athletes benefit from resistance training that mirrors their sport's demands. This functional training approach not only improves muscular strength but also preserves or enhances muscular endurance at sport-relevant intensities and movement patterns.

Study 4: Strength Training's Effect on Endurance Performance Determinants

is Endurance athletes often wonder: Will strength training help or hurt my endurance performance? This umbrella review by Ramos-Campo et al(2025) examined decades of research on middle-distance and long-distance runners, cyclists, and other endurance athletes.

The comprehensive analysis revealed that supplementing endurance training with moderate resistance training improved multiple endurance performance determinants, including:

• Running economy: Better energy efficiency at sustained paces

• Lactate threshold: Higher intensity sustainable without rapid fatigue

• Maximum oxygen uptake (VO₂ max): Improved aerobic capacity

• Neuromuscular power: Better force application in late-race scenarios

Notably, moderate-intensity strength training (not heavy power-focused training) provided the greatest endurance performance benefits when integrated with traditional endurance training. The key was periodization and strategic timing to avoid interference with aerobic adaptations.

Key Takeaway: Endurance athletes should incorporate 2-3 sessions per week of moderate-intensity resistance training focused on lower body and core stability. This approach enhances multiple endurance performance determinants without compromising aerobic adaptations.

Real-World Application: A marathon runner might dedicate two sessions weekly to resistance training targeting legs and core, using moderate loads (60-75% 1RM) with higher repetitions (10-15 reps). This strategy improves running economy, strengthens stabilizer muscles to prevent injury, and enhances late-race neuromuscular capacity.

Study 5: Muscle Mass's Role in Endurance Performance and Neuromuscular Fatigue (Metabolic Armour)

Here's a finding that challenges common endurance training wisdom: more muscle mass may enhance endurance performance and reduce neuromuscular fatigue.

Zhang et al. (2025) conducted a systematic review and meta-analysis examining how muscle mass relates to endurance performance determinants and resistance to neuromuscular fatigue. Their meta-analysis synthesized data from numerous studies tracking athletes with varying levels of muscle mass.

How Greater Muscle Mass Influences Endurance Performance

• Improved Neuromuscular Fatigue Resistance
  Greater muscle mass enhances the ability to sustain force output during repeated or prolonged efforts by distributing workload across a larger pool of motor units, delaying neuromuscular fatigue.

• Enhanced Muscular Power Output
  Increased lean muscle tissue supports higher force production during critical moments such as finishing kicks, sprint surges, and late-race accelerations, improving competitive performance.

• Better Metabolic Efficiency
  Higher muscle mass improves metabolic flexibility, enabling more efficient utilization of both carbohydrates and fats, reducing early glycogen depletion and supporting sustained endurance output.

• Reduced Injury Risk and Improved Musculoskeletal Resilience
  Well-developed muscle mass increases joint stability and load tolerance, lowering the risk of overuse and repetitive-strain injuries

  .

The meta-analysis showed that endurance athletes with greater muscle mass demonstrated superior resistance to neuromuscular fatigue in the latter stages of competition. This doesn't mean becoming a bodybuilder, but rather building a functional amount of lean muscle tissue specifically in the posterior chain, core, and stabilizer muscles.

Key Takeaway: Endurance performance isn't just about being lean—muscle mass, particularly in legs and core, directly contributes to neuromuscular fatigue resistance and late-race performance. Strategic resistance training to build sport-specific muscle mass is a legitimate endurance training strategy.

Scientific Perspective: Greater muscle mass provides a larger pool of motor units, improving the ability to distribute neuromuscular fatigue across multiple units. Additionally, more muscle tissue means greater metabolic capacity and better ability to sustain power during crucial moments in endurance events.

Synthesizing the Evidence: How These Studies Connect

These five studies paint a comprehensive picture of how muscular endurance, strength adaptations, and endurance performance interact. Here's the interconnected story:

• Cross-education effects (Song et al.) suggest that unilateral training can produce bilateral muscular endurance benefits—a frontier for future research.

• Resistance training improves absolute muscular endurance reliably, but relative muscular endurance requires specific programming (Hammert et al)

• Functional resistance training (Gürkan et al.) bridges the gap between strength development and sport-specific muscular endurance, making it ideal for athletes.

• Endurance athletes benefit significantly from supplemental resistance training integrated strategically into their programs (Ramos-Campo et al.).

• Building muscle mass through resistance training directly improves endurance performance and neuromuscular fatigue resistance (Zhang et al.), suggesting strength work is not antithetical to endurance goals.

Practical Training Recommendations Based on Current Research

For Strength and Power Athletes

• Incorporate higher-repetition resistance training blocks (2-3 weeks) using 50-70% of 1RM with 15-25 repetitions to develop absolute muscular endurance. This prevents plateaus and improves work capacity. Monitor relative muscular endurance separately to ensure it doesn't decline excessively during hypertrophy phases.

For Endurance Athletes

• Add 2-3 weekly resistance training sessions focusing on legs, glutes, and core with moderate loads (60-75% 1RM) and 10-15 repetitions. This approach enhances running economy, builds protective muscle mass, improves neuromuscular fatigue resistance, and maintains endurance performance determinants. Avoid heavy max-strength work that might interfere with aerobic adaptations.

For Functional Athletes (CrossFit, Team Sports, etc.)

• Prioritize functional resistance training that mirrors your sport's demands. Include compound movements at moderate loads with higher repetitions (8-12 reps per set) to develop sport-specific strength and endurance adaptations simultaneously. This strategy produces superior muscular endurance at the precise movement patterns and intensities you'll need in competition.

For Injury Rehabilitation

• Explore whether cross-education training (training the uninjured limb) might enhance muscular endurance recovery in the injured limb. While definitive protocols aren't yet established, this emerging area shows promise for maintaining fitness during recovery periods.

Frequently Asked Questions About Muscular Endurance and Strength Training

Q1: Will doing strength training ruin my endurance performance?
No, if done correctly. Strategic resistance training (2-3 sessions weekly at moderate intensity) enhances endurance performance determinants without interfering with aerobic adaptations. The key is using moderate loads and higher repetitions, not heavy max-strength protocols.

Q2: Is it better to train absolute muscular endurance or relative muscular endurance?
It depends on your sport. Athletes in explosive sports (track, gymnastics) benefit from maintaining relative muscular endurance alongside strength development. Endurance athletes should focus on building absolute muscular endurance and muscle mass through moderate-load resistance training.

Q3: How much muscle mass is optimal for endurance athletes?
Research suggests that endurance athletes benefit from 1-2% additional muscle mass in legs and core compared to minimal-strength baselines. This provides neuromuscular fatigue resistance and improved endurance performance determinants without excessive weight gain affecting power-to-weight ratios.

Q4: Can cross-education help me maintain muscular endurance during injury?
This is an exciting frontier. While cross-education of strength is proven, cross-education of muscular endurance needs more research. However, training your uninjured limb while recovering likely provides some systemic benefits through neural pathways and circulating factors.

Q5: How should I program resistance training alongside my endurance training?
Perform resistance training on separate days or as secondary work after reduced-volume endurance sessions, not on high-volume endurance days. This prevents excessive fatigue accumulation. Prioritize functional resistance training targeting sport-specific movements at moderate intensity.

Q6: Does functional resistance training really produce better strength and endurance adaptations than traditional training?
Research on elite field hockey players shows functional resistance training produces superior combined strength and muscular endurance adaptations. Sport-specific movement patterns activate stabilizers and create transferability to competition performance.

The Bottom Line: Integration is Key

The convergence of these five studies reveals a fundamental truth: muscular endurance, strength development, and endurance performance aren't competing goals. They're integrated components of overall athletic development. Whether you're a sprinter, marathoner, field hockey player, or functional fitness athlete, strategic resistance training tailored to your specific needs improves both absolute muscular endurance and sport-specific muscular endurance capacity while building the muscle mass and neuromuscular resilience that distinguishes champions.

The future of strength and conditioning training lies in personalized programming that respects sport-specific demands, periodizes between strength development and muscular endurance phases, and recognizes that muscle tissue is an endurance athlete's asset—not liability.

Ready to Apply This Research to Your Training?
Now that you understand the science behind muscular endurance adaptations and strength training effectiveness, it's time to implement these evidence-based strategies. Consider working with a strength and conditioning professional to develop a periodized program that optimizes your absolute and relative muscular endurance, builds sport-specific muscle mass, and improves your endurance performance determinants.

Remember: Progressive resistance training isn't just for bodybuilders—it's a cornerstone of elite endurance and functional athlete development.

Author’s Note

This article synthesizes the latest peer-reviewed research on muscular endurance, strength training adaptations, and endurance performance, providing evidence-based guidance for athletes, coaches, and health professionals. The content is intended for educational purposes and reflects studies published through February 2025. While every effort has been made to ensure accuracy, individual responses to training may vary based on genetics, age, training history, and other factors. Readers are encouraged to consult healthcare professionals or certified strength and conditioning coaches before implementing new exercise programs.

Medical Disclaimer

The information in this article, including the research findings, is for educational purposes only and does not constitute medical advice, diagnosis, or treatment. Before starting a resistance exercise program, you must consult with a qualified healthcare professional, especially if you have existing health conditions (such as cardiovascular disease, uncontrolled hypertension, or advanced metabolic disease). Exercise carries inherent risks, and you assume full responsibility for your actions. This article does not establish a doctor-patient relationship.

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References

Song, J. S., Yamada, Y., Kataoka, R., & et al. (2024). Cross-education of muscular endurance: A scoping review. Sports Medicine, 54, 1771–1783. https://doi.org/10.1007/s40279-024-02042-z

Hammert, W. B., Yamada, Y., Kataoka, R., Song, J. S., Spitz, R. W., Wong, V., Seffrin, A., & Loenneke, J. P. (2025). Changes in absolute and relative muscular endurance after resistance training: A review of the literature with considerations for future research. Journal of Strength and Conditioning Research, 39(4), 474–491. https://doi.org/10.1519/JSC.0000000000005084

Gürkan, A. C., Eraslan, M., Aydın, S., Altuğ, T., Türkmen, M., Söyler, M., Mülhim, M. A., Şahin, M., Karataş, B., Akcan, İ. O., & Küçük, H. (2025). Muscular strength and endurance adaptations to functional resistance training in young elite field hockey players. Frontiers in Physiology, 16, Article 1536885. https://doi.org/10.3389/fphys.2025.1536885

Ramos-Campo, D. J., Andreu-Caravaca, L., Clemente-Suárez, V. J., & Rubio-Arias, J. Á. (2025). The effect of strength training on endurance performance determinants in middle- and long-distance endurance athletes: An umbrella review of systematic reviews and meta-analysis. Journal of Strength and Conditioning Research, 39(4), 492–506. https://doi.org/10.1519/JSC.0000000000005056

Zhang, J., Pearson, A. Z., Grunau, M., & et al. (2025). The role of muscle mass in endurance performance and neuromuscular fatigue: A systematic review and meta-analysis. Sports Medicine, 55, 2809–2824. https://doi.org/10.1007/s40279-025-02290-