Muscular Endurance

Muscular Endurance (Strength Endurance, Endurance Strength)

Muscular endurance is the ability to sustain force production or perform repeated muscle contractions against a given load over time.

In resistance training, muscular endurance is often operationalized as the ability to perform more repetitions with a submaximal load. However, current evidence suggests that muscular endurance is highly specific to the task being trained, including the load, velocity, range of motion, contraction type, and exercise selection. For this reason, muscular endurance is likely best viewed as task-specific fatigue resistance during force production, rather than as a wholly distinct physical quality. Although the terms muscular endurance, strength endurance, and endurance strength remain useful for communication, they may be somewhat misleading if they imply a single general adaptation that transfers broadly across all resistance training tasks.

Semantic Clarification

Local muscular endurance vs. aerobic endurance

• Local muscular endurance: Fatigue resistance in a specific muscle group or movement pattern during repeated contractions or sustained submaximal force production.
• Aerobic endurance: The ability to sustain whole-body activity over time, generally supported by oxidative metabolism and cardiorespiratory function. Although aerobic adaptations may contribute to recovery between repeated efforts, aerobic endurance and local muscular endurance are not interchangeable.

Muscular endurance vs. strength

• Muscular endurance: The ability to sustain force production or perform repeated muscle contractions against a given load over time.
• Strength: The ability to produce force, often measured as maximal force output. Strength contributes to muscular endurance because increasing maximal force may reduce the relative intensity of a given submaximal load. However, strength alone does not fully determine repetition performance, and improvements in muscular endurance are also dependent on specific practice with the target task.

Muscular endurance vs. work capacity

1. Muscular endurance: A performance quality referring to the ability to sustain repeated contractions or continue force production during a specific task.
2. Work capacity: A broader programming term referring to the amount of training stress or total work an individual can perform and recover from. Work capacity may influence muscular endurance training tolerance, but the terms should not be treated as synonymous.

Frequently Asked Questions (FAQs)

Can increasing maximal strength improve muscular endurance?

• Yes. Increasing maximal strength can improve muscular endurance by reducing the relative intensity of a submaximal load. For example, if a load that was once 80% of 1-RM becomes 70% of 1-RM, more repetitions can often be performed. However, strength gains alone are unlikely to maximize repetition performance across all loads. If the goal is to perform more repetitions at a specific load, some training should be performed at or near that load.

Do I need light loads and very high reps to train muscular endurance?

• Not necessarily. If the goal is to improve performance with lighter loads, then lighter-load training is likely beneficial. However, if the goal is to perform more repetitions with a moderate or heavier load, then training should include work that more closely matches that load. This is one reason the term “muscular endurance” can be misleading. The best training depends on the exact task.

Is training to failure required for muscular endurance?

• Not in every set. Training close to failure is often useful for improving repetition performance, especially with lighter and moderate loads, but taking every set to failure may create excessive fatigue and impair performance in later sets or sessions. For many individuals, a combination of sets taken close to failure, with selective use of failure, is likely to be an effective and more sustainable strategy.

Do drop sets improve muscular endurance?

• They can. Drop sets may be an efficient strategy for accumulating more repetitions and increasing local fatigue resistance, especially in experienced exercisers. They may also reduce the need for separate endurance-focused training in some programs. However, drop sets should generally be considered a progression, not a requirement.

Is muscular endurance training necessary if the goal is hypertrophy or general fitness?

• Not always. For many individuals, especially those training for hypertrophy or general fitness, separate muscular endurance training may be deprioritized because moderate-load training performed near failure, circuit training, and drop sets may already provide sufficient exposure to repeated-effort demands. More specific muscular endurance training is most useful when repetition performance at a particular load or under a particular set of task constraints is itself the goal.

Brookbush Institute's Endurance Training Model: Comprehensively Evidence-based and Outcome-driven

1. Tempo:
   • General Recommendation: 2-4 seconds eccentric: 0-2 seconds isometric: maximum velocity or longer concentric (2-4: 0-2: MaxV+)
   • Goal-specific: Strength and endurance may be velocity-specific. If the general training recommendation above does not align with the demands of the individual's sport or goal, it may be advisable to use a tempo that better matches the individual's goal.
2. Reps-to-Failure/set: Perform reps-to-failure/set for most, if not all, sets. Note that athletes performing high-frequency training should likely perform 1-2 reps-in-reserve/set, and 1 additional set to maintain volume, when training is followed by practice or games. Even if the primary goal is endurance.
3. Reps and Load:
   • Young Novice Exercisers and Adults: High reps or goal-specific loads (Endurance strength is likely specific to load and exercise).
   • Elderly Exercisers: Moderate reps (larger improvements in functional outcomes)
   • Reps and Load:
     • Most: Light 12 - 25 RM/set (50 - 70% of 1-RM).
     • Some: Moderate: 8 - 12 RM/set (70 - 80% of 1-RM)
     • A little: Heavy: 3 - 8 RM/set (80 - 95% of 1-RM)
     • Avoid: Very Heavy: 1-2 RM/set (95 - 100% of 1-RM)
     • Avoid: Very Light: 25 or more RM/set (≤50% of 1-RM)
4. Range of Motion (ROM): Exercise should be performed with the largest ROM that can be performed without pain and with good form (That is, form that is free from signs correlated with dysfunction, injury, or pain). However, increasing load to improve endurance, strength, and hypertrophy is likely to be beneficial, even if it results in a temporary reduction in exercise ROM.
5. Rest Between Sets and Circuits: Moderate (2 min) to long (3 min) rest between sets for similar muscle groups, or circuit training with short (30-60 sec) rest between exercises. Note that longer rest periods may be more necessary for optimizing endurance training than for other training goals.
6. Set strategies:
   • Pyramid sets are not recommended.
   • Agonist/antagonist supersets or circuit training are recommended to increase workout efficiency.
   • Drop sets are recommended as a progression for advanced exercisers who can benefit from higher exercise volumes (currently performing 3 or more conventional sets/muscle group). Drop sets have been shown to significantly increase endurance, potentially more than conventional set strategies. It may be reasonable to suggest that, for many individuals, specific endurance training may be unnecessary if drop sets are incorporated regularly.
7. Sets/Muscle Group/Session: A progressive increase from 1-5 sets/muscle group/session
   • Novice Exercisers (6-12 weeks): 1 - 2 sets/upper body muscle group, 2-3 sets/lower body muscle group
   • Experienced Exercisers: 2-5 sets
   • Supersets and Drop-sets: 1-4 sets
8. Training Frequency:
   • General recommendation: 1.5 - 3 sessions/muscle group/week and 2-5 days rest between sessions
     • Starting a new routine: 3 sessions/muscle group/2 weeks and 3 - 7 days rest between sessions. Alternatively, consider scheduling "de-loading weeks" after the first session of a new routine (not the last session of a routine).
     • Initial Training Period (8-12 weeks): 1 - 3 sessions/muscle group/week
     • Maintenance: 1-2 sessions/muscle group/week
     • High-volume (Advanced) Training: 4 or more resistance-training sessions/week require split routines.
9. Recommended Training Splits:
   • 1 - 2 days/week = total body
   • 3 days/week = total body or upper/lower split
   • 4 days/week = upper/lower split
   • 5 - 6 days a week (not recommended for resistance training) = Upper/lower/recovery split or Push/Pull/Legs
10. Periodization for Hypertrophy
    • Maximize exposure to goal-specific acute variables: Most time spent with moderate loads, followed by heavy loads, with some lighter load training when necessary to reduce intensity or introduce a new stimulus. Note that drop sets may reduce the need for light-load/high-rep training.
    • Load adjustments: Auto-regulated, frequent, adaptive intra-session or session-to-session load adjustments. Increase load when more reps than the upper limit of the rep range can be performed, and decrease load if the lower limit of the rep range can not be performed.
    • Novice Exercisers: Periodization will not result in better outcomes for at least the initial 12 weeks. Perform moderate loads and reps/set with auto-regulated load adjustments.
    • Experienced Exercisers: True linear periodization with daily undulation is likely the most effective strategy. Although block periodization is unlikely to result in additional benefits, it can be helpful to organize a training program into phases and then blend those phases with a linear progression of loads.
    • Endurance Goal: Recommended Progression of Periodization Strategies
      • Goal: Optimizing the number of repetitions that can be performed at submaximal loads.
        1. True linear periodization (with frequent, auto-regulated load adjustments), with light to moderate loads
        2. True linear periodization (with frequent, auto-regulated load adjustments), progressing from light to moderate (and potentially heavy loads).
        3. True linear periodization with daily undulation (with frequent, auto-regulated load adjustments), including light/high rep days, moderate load days, and intermittent periods incorporating heavy loads.
        4. True linear periodization with daily undulation (with frequent, auto-regulated load adjustments), including light/high rep days, moderate load/hypertrophy days with drop sets, and intermittent periods incorporating heavy loads.
        5. True linear periodization with daily undulation (with frequent, auto-regulated load adjustments), including light/high rep days, moderate load/hypertrophy days with drop sets, and heavy load days with drop sets (frequent, auto-regulated load adjustments).
11. Exercise Order:
    • Start with your most important exercises
    • Start with large muscle groups and multi-joint movements
    • When priorities are equal, perform upper-body exercises before lower-body exercises
    • Program back exercises before chest when both are trained in the same routine
    • Perform strength training before aerobic training
    • To optimize performance on a key lift, avoid training similar muscles in the same session
12. Exercise Selection: The stability challenge of an exercise during endurance training should be relatively unstable (6-10/10), whereas on moderate- and heavy-load days, exercises should be moderately stable or stable (1-6/10).

Additional Courses

• Hypertrophy Training: Evidence-based Model
• Strength Training: Evidence-based Model

Additional Articles:

• Muscular Endurance Training Deprioritized
• Drop Sets: Comprehensive Systematic Review and Training Recommendations

Additional Glossary Terms

• Drop sets