Strength or Endurance? A Deep Dive into the Tactical Fitness Showdown

Topics Covered

1. Strength: Definition and Manifestation

2. Endurance: Definition and Manifestation

3. Role of Strength and Endurance in Tactical Settings

4. The Concurrent Training Approach

5. Its application in tactical settings

6. What about the other abilities?

Summary

In this article, we explore the ongoing debate between prioritising strength and endurance in tactical settings. The discussion highlights the biomotor abilities that underpin physical performance, with a focus on strength and endurance, their manifestations, and their respective roles in operational readiness. The article also examines the interference effect of concurrent training, proposing strategies to balance these physical qualities and mitigate this effect. It concludes with practical training approaches, solutions, and examples to help professionals optimise performance in unpredictable operational contexts.

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The complex demands required to accomplish the vast heterogeneity of tasks in tactical settings result in the need for a diverse range of physical abilities. Within these communities, the debate over the prioritisation of strength or endurance is common, extending not only to readiness but also to well-being and longevity, with specialists arguing for each side at the expense of the other. As such, the question arises: which should take precedence in training programs—strength or cardiovascular fitness?

Let’s take a deep look at each side.

Biomotor abilities refer to the physical qualities that influence an individual’s performance in motor tasks, encompassing various aspects of physical fitness and coordination. These abilities are fundamental for athletic performance, readiness, and general movement.

The literature typically refers to five main biomotor abilities:

Strength: The ability to generate force.

Speed: The ability to perform movements quickly.

Endurance: The ability to sustain effort over time.

Flexibility: The ability to move joints through their full range of motion.

Coordination: The ability to integrate different body movements smoothly and efficiently.

These abilities interact and contribute to overall physical performance, with each being trainable to varying degrees (1,2).

1. Strength: Definition and Manifestation

Strength is the ability of a muscle or muscle group to exert force against resistance. This ability plays a role in nearly every movement, from basic activities like standing up or lifting objects to complex actions in sports, occupational tasks, and other physical activities (2). Strength can be classified into different types of manifestations, including maximal strength, explosive strength, and strength endurance, each with distinct characteristics and roles in physical performance:

Maximal Strength is the greatest force that can be voluntarily produced by a muscle or muscle group in a single effort, commonly assessed using the one-repetition maximum (1RM). It focuses solely on the magnitude of the force without consideration of the speed or time of execution​​.

Explosive Strength is the ability of the neuromuscular system to exert the maximum amount of force in the shortest possible time. It is critical for activities that require rapid acceleration, such as sprinting, jumping, or throwing​​​.

Strength Endurance refers to the capacity to sustain submaximal levels of force over time, which is important for repetitive tasks (1–4).

There are several factors that can affect the manifestation of strength, which can be categorised into neural and muscular factors. More specifically, these include motor unit recruitment, firing frequency (rate coding), motor unit synchronisation, neuromuscular inhibition, the stretch-shortening cycle (SSC), muscle fiber type, and muscle hypertrophy (1,5).

To fully understand these concepts, it is essential to distinguish between intra- and intermuscular coordination. Intramuscular coordination focuses on the activation of individual muscle fibers within a single muscle, while intermuscular coordination refers to the activation of multiple muscles working together. Both forms of coordination aim to achieve maximal exertion at their respective levels. However, as the complexity of exercises increases, the skill demands and intermuscular coordination become more crucial (6).

2. Endurance: Definition and Manifestation

Endurance is typically defined as the capacity to perform repetitive or sustained physical activity over a prolonged period without experiencing excessive fatigue. This ability involves both the muscular and cardiovascular systems and is essential for maintaining performance in a wide range of activities. Depending on the context, endurance can be described in two primary forms: muscular endurance and cardiovascular endurance (2,7):

Muscular endurance is primarily associated with the muscle fibers’ ability to resist fatigue. It involves both type I muscle fibers (slow-twitch fibers) and type II muscle fibers (fast-twitch fibers). However, slow-twitch fibers play a dominant role in activities requiring endurance due to their higher fatigue resistance (2,3,5).

Cardiovascular endurance, also known as cardiorespiratory fitness, involves the efficient functioning of the heart, lungs, and circulatory system. This form of endurance is particularly important in aerobic activities, where oxygen is required for continuous energy production (1,2).

This biomotor ability is crucial for sustaining prolonged efforts and can be seen in both physiological and performance-related outcomes. At a physiological level, regular aerobic exercise results in adaptations such as an increase in stroke volume (the amount of blood pumped per heartbeat), a reduction in resting heart rate, improved oxygen delivery to muscles, increased capillary density, mitochondrial biogenesis, and enhanced oxidative enzyme activity, which collectively boost the body's ability to utilise oxygen and metabolise substrates effectively. Performance-wise, individuals with high cardiovascular endurance can sustain intense physical activity for longer durations without significant fatigue, recover faster between intense bouts of exercise, and demonstrate improved metabolic efficiency and recovery times, enabling higher intensity or longer duration performances (5,8).

In practical terms, this means individuals can sustain performance during prolonged activities and recover more quickly between efforts, thereby reducing overall fatigue during training or duty (2,9).

3. Role of Strength and Endurance in Tactical Settings

Strength is foundational for many of the physical demands encountered by tactical professionals. Tasks such as lifting and carrying heavy loads, breaching doors, subduing suspects, or operating heavy machinery require significant muscular strength. The literature highlights several benefits of strength in tactical populations:

Injury Prevention: Increased muscular strength has been shown to reduce the incidence of injuries. Stronger muscles, tendons, and ligaments are better equipped to handle sudden, intense forces encountered in operational scenarios (10–12).

Load-Bearing Capacity: Tactical professionals frequently carry heavy equipment, sometimes exceeding 30% of their body weight. Higher relative strength levels correlate with improved task efficiency during load-bearing activities, possibly by improving posture and energy efficiency during load carriage  (13–16).

Operational Performance: Studies have demonstrated that greater maximal strength is associated with improved performance in key tactical tasks such as lifting, dragging, and sprinting with equipment (11,17).

Improved Power Output: Explosive strength is critical for generating rapid, forceful movements, essential in activities like sprinting, tackling, or climbing obstacles. Power, defined as the product of strength and speed, enables tactical personnel to execute high-intensity tasks quickly and efficiently, which is often vital in life-or-death scenarios (11).

Enhanced Endurance in Physically Demanding Situations: Strength endurance training plays a key role in developing muscular endurance, allowing personnel to sustain physical efforts over extended periods and perform repetitive tasks with reduced fatigue (11,18).

Enhanced Operational Readiness: Strength training improves operational readiness by ensuring personnel are physically prepared to meet the demands of their roles. This training enhances their ability to perform tasks more effectively and adapt to changing conditions (11,16–18).

Cardiovascular endurance is a critical ability for operational effectiveness in various high-demand professions. These roles often require individuals to perform sustained, high-intensity activities under challenging conditions, highlighting the importance of an efficient cardiovascular system to support oxygen transport and utilisation by muscles during prolonged exertion (11).

Several operational tasks or combat-related actions, heavily rely on aerobic capacity. The physical demands are intensified by environmental factors like extreme temperatures or altitude, psychological stressors, and the need for rapid decision-making in potentially hazardous scenarios. Thus, maintaining high cardiovascular fitness is essential for optimal performance under such circumstances (19). The key contributions of cardiovascular endurance are:

Injury Prevention: A strong cardiovascular system enhances muscle efficiency and reduces the risk of musculoskeletal injuries from overuse or strain (20,21).

Load-Bearing Capacity and Sustaining Extended Efforts: Activities such as military marches with heavy equipment, extended firefighting tasks, or casualty drag exemplify the need for prolonged high-intensity performance supported by robust cardiovascular endurance. Aerobic fitness was identified as the primary determinant of load carriage performance, likely due to the oxidative demands of prolonged tasks (11,16,22).

Efficient Recovery: Enhanced cardiovascular fitness allows for rapid replenishment of oxygen stores between intense activities, reducing fatigue and maintaining operational readiness (11,23).

Cognitive Support: Physical exhaustion can impair cognitive functions such as decision-making and situational awareness. Cardiovascular fitness ensures adequate oxygen delivery to the brain, helping maintain mental acuity under stress (11).

As we now understand, both biomotor abilities are essential for tactical readiness. While the relative importance of each ability depends on the specific requirements of each role, both are fundamental to ensuring operational effectiveness.

With this in mind, how can we effectively balance their training?

4. The Concurrent Training Approach

One potential strategy is to utilise a concurrent training approach. This approach integrates resistance training (strength) and endurance (aerobic) training within the same training period, aiming to develop both physical qualities simultaneously. Concurrent training is particularly beneficial for individuals or athletes who require a balance between strength and endurance capabilities, such as tactical personnel. The system is goal-oriented, rooted in the principle of specificity, and considers the interference effect​​ (2,5,11,15). 

The interference effect, also referred to as the interference process, it remains a topic of considerable debate within the academic community. While there is no unanimous consensus, it is widely acknowledged that training for multiple physical fitness qualities can sometimes lead to suboptimal adaptations in one or both biomotor abilities. This may occur due to factors like neural fatigue or molecular pathway conflicts, collectively termed the interference process. This phenomenon is especially relevant in concurrent training scenarios where endurance and resistance exercises are combined within the same period​​ (24).

Theoretically, the primary mechanisms driving the interference effect include fatigue, substrate depletion, and compromised signalling pathways for protein synthesis. Fatigue impacts adaptation significantly; performing endurance training before strength training can reduce force production and impair muscle recruitment, leading to less optimal strength adaptations. Conversely, performing strength training before endurance work might hinder aerobic performance due to residual fatigue. Furthermore, endurance training predominantly activates pathways like the Activated Protein Kinase (AMPK) pathway, which promotes mitochondrial biogenesis and aerobic capacity. In contrast, strength training primarily activates the Mammalian Target of Rapamycin (mTOR) pathway, which supports protein synthesis and muscle hypertrophy. Importantly, AMPK activation can inhibit mTOR signalling, thereby reducing muscle protein synthesis and strength adaptations​​ (5).

So, how can we mitigate the interference effect?

A multifaceted approach is required to mitigate the negative effects of concurrent training. Key strategies include designing programs with temporal separation, ensuring that endurance and resistance training sessions are performed at least 6–8 hours apart or on separate days to minimise acute molecular and metabolic conflicts. Prioritisation should be implemented by emphasising the quality most relevant to an individual's goals, such as strength or endurance, within specific training blocks. Periodisation is another crucial element, involving the structuring of training into distinct phases that focus on either endurance or strength to optimise adaptations while minimising chronic interference (5,7,24–26).

Exercise selection plays a significant role, with an emphasis on avoiding high-impact or excessively fatiguing endurance activities, such as long runs, immediately before or after strength training. Incorporating high-intensity, low-volume endurance exercises, such as maximum and supra-maximum high-intensity interval training (HIIT) or sprint interval training (SIT), can help limit the activation of AMPK. Proper nutrition or nutritional support is also essential, incorporating adequate protein intake and carbohydrate replenishment to promote recovery and adaptation across training modalities. Finally, recovery strategies, including optimising sleep, maintaining proper hydration, and incorporating active recovery techniques, are fundamental for reducing fatigue and enhancing overall adaptation​​​ (5,7,24–26).

Thus, the key takeaways of concurrent training are:

Concurrent training can improve strength, hypertrophy, and power compared to endurance training alone, albeit not as effectively as resistance training alone. However, aerobic capacity improvements are comparable to those achieved with endurance training when well-designed.

Resistance training combined with running often results in greater interference in strength and hypertrophy gains compared to cycling, likely due to the eccentric nature of running, which induces more muscle damage than cycling's concentric activity.

Higher frequency and longer duration of endurance training can negatively impact strength, power, and hypertrophy gains. Incorporating HIIT or SIT as endurance sessions and scheduling resistance and endurance training on separate days can slightly reduce interference compared to same-day sessions.

To maximise resistance training adaptations for muscle mass, resistance exercises should be performed before endurance exercises.

To maximise endurance training outcomes, or when resistance training adaptations are of lower priority, endurance exercises should be performed before resistance exercises.

Concurrent training has been shown to produce the most significant reductions in body fat, particularly when high-intensity endurance exercises are included.

Power output is more adversely affected by concurrent training than strength or hypertrophy, possibly due to impairments in the rate of force development or movement velocity.

Considering the individual's training experience and background is of high importance  (24,26,27).

5. Its application in tactical settings

The key challenge in tactical training settings is aligning this approach with the unpredictable nature of operational contexts. In tactical professions, duty often takes precedence over sleep, nutrition, and other factors, necessitating an approach that is both flexible and adaptable in concurrent training applications. Below are key considerations and practical solutions designed to mitigate the challenges in tactical contexts:

Temporal Separation: Tactical operators often face irregular schedules, making it difficult to control the timing of training. To minimise conflicts, prioritise mission-critical tasks and schedule physical training during periods of low operational intensity. When longer breaks aren’t feasible, incorporate microdosing—short, focused training sessions that maximise effectiveness even when time is limited.

Prioritisation in Training Blocks: A comprehensive needs analysis based on mission demands is essential for effective training (11). For example, strength is essential for handling heavy equipment, while endurance is vital for sustaining operations over time. During specific training phases, prioritise the most critical attributes while preserving baseline proficiency in other areas with maintenance 'doses'. This strategy ensures operators are prepared for immediate mission demands.

Periodisation and Programming: Utilise undulating periodisation to enable frequent shifts between endurance and strength training without causing long-term disruptions. Design training programs that are adaptable and can be modified based on time constraints and available equipment, ensuring flexibility without compromising readiness (1). One example is the 3-to-5 method, proposed by Pavel Tsatsouline (28), which emphasises performing 3 to 5 reps per set, completing 3 to 5 sets per exercise, scheduling 3 to 5 sessions per week, and focusing on compound, multi-joint movements. This method associated with a split routine will supports strength development while minimising excessive fatigue, ensuring sufficient volume for adaptation. For cardiorespiratory fitness training, HIIT protocols, such as high-intensity training long (HIT-L), short (HIT-S), or SIT, can be effective alternatives to traditional long, slow distance sessions. These shorter, intense sessions, when well-structured and executed, can achieve comparable or even superior results in less time (2,4).

Combining sessions of various activities throughout the weekly program, such as running, indoor cycling, air-resistance biking, or indoor rowing, can help minimize impact, reduce interference effects, and maintain cardiovascular stimulation (24, 26).

There are plenty of well-established protocols; here is one example for each:

HIT-L: 3 sessions per week consisting of 4 to 6 intervals of 4-minute submaximal runs, each followed by 2 minutes of active rest.

HIIT-S: 3 sessions per week consisting of 12 to 15 intervals of 15 seconds near-maximal runs, each followed by 15 seconds of active rest.

SIT: 3 sessions per week consisting of 5 to 8 intervals of 30-second supramaximal sprints, each followed by 3 to 4 minutes of rest (4).

To ensure the effectiveness of this method, it is crucial to monitor the intensity of the sessions is crucial. Tools such as the Maximum Aerobic Speed (MAS), heart rate monitors, or perceived exertion scales can help gauge effort levels. These approaches allow for efficient training while maximising physiological adaptations.

Exercise Selection: The selection of exercises should depend on the available training facilities; however, it is essential to focus on functional movements that transfer to real-world mission tasks and demands. Lifting heavy objects from the ground or carrying a person is just some examples of the many multi-joint exercises requiring a high capacity to produce strength in a non-controlled environment. This type of exercise demands not only high intramuscular coordination but also significant intermuscular coordination. Therefore, isolated strength exercises (which involve movement at a single joint) should only supplement the primary training program. Strength training machines, while providing stability and targeting specific muscles, create a safer environment, which is useful for individuals recovering from injuries, for bodybuilders, or for other specific purposes. However, they cannot enhance intermuscular coordination, which is crucial for functional transfer to daily activities, tactical situations, or even sports contexts (3,5,6). Thus, these machines should not be the primary training tool for injury-free tactical personnel.

Nutrition: An irregular schedule often leads to poor nutritional habits. As optimal nutrition is crucial for minimising the interference effect, weekly meal planning and preparation can help reduce reliance on quick, less nutritious options like fast food. When optimal nutrition isn’t available, lightweight, nutrient-dense options should be prioritised (11).

Recovery Strategies: Sleep and recovery often take a back seat due to unpredictable schedules and operational stress. Focus on active recovery methods such as stretching and mobility work that can be performed in a limited time and space. Incorporate mindfulness and stress-management techniques to address both psychological and physiological stress. Additionally, use wearables (if feasible) to monitor recovery metrics, enabling data-driven adjustments to train intensity and optimising recovery (11).

Monitoring and Adjustment: The highly variable nature of stressors in tactical environments makes consistent training assessments challenging. To guide training modifications, use subjective wellness ratings (e.g., sleep quality, fatigue, soreness) in conjunction with mission-readiness assessments, or wearables. Periodic functional fitness tests can help ensure that operators maintain readiness while avoiding excessive fatigue and overtraining (11).

Below you can see typical weekly schedules utilising concurrent training approach:

Day	Session
Monday	Resistance Training (Strength Focus)
Tuesday	Rest
Wednesday	Intervals Training (Aerobic Endurance Focus) Running Session
Thursday	Rest
Friday	Resistance Training (Strength Focus)
Saturday	Low, Slow Distance (Aerobic Endurance Focus)
Sunday	Rest

Table 1. A 4 sessions per week training program.

Day	Session
Monday	Resistance Training (Strength Focus)
Tuesday	Interval Training (Cardiovascular Endurance Focus) Indoor Cycling Session
Wednesday	Rest
Thursday	Resistance Training (Strength Focus)
Friday	Interval Training (Cardiovascular Endurance Focus) Running Session
Saturday	Rest
Sunday	Long, Slow Distance (Cardiovascular Endurance Focus)

Table 2. A 5 sessions per week training program.

Day	Session
Monday	Resistance Training (Strength Focus)
Tuesday	Interval Training (Cardiovascular Endurance Focus) Indoor Cycling Session
Wednesday	Resistance Training (Strength Focus)
Thursday	Interval Training (Cardiovascular Endurance Focus) Running Session
Friday	Rest
Saturday	Resistance Training (Strength Focus)
Sunday	Long, Slow Distance (Cardiovascular Endurance Focus)

Table 3. A 6 sessions per week training program.

Day	Morning Session	Evening Session
Monday	Resistance Training (Strength Focus)	Interval Training (Cardiovascular Endurance Focus) Running Session
Tuesday	Interval Training (Cardiovascular Endurance Focus) Indoor Cycling Session	Core and Mobility
Wednesday	Resistance Training (Strength Focus)	Interval Training (Cardiovascular Endurance Focus) Running Session
Thursday	Resistance Training (Strength Focus)	Rest
Friday	Resistance Training (Strength Focus)	Interval Training (Cardiovascular Endurance Focus) Indoor Cycling Session
Saturday	Active Recovery	Core and Mobility
Sunday	Long, Slow Distance (Cardiovascular Endurance Focus)	Rest

Table 4. A 7-day two-a-day training program with a strength emphasis.

Take into consideration that these tables focus only on physical fitness, and do not refer to tactical-technical sessions, which ideally should be practiced daily.

6. What about the other abilities?

Despite this article focusing primarily on the dichotomy between strength and endurance training, it is important to acknowledge the essential role of other biomotor abilities and skills, such as velocity (particularly contextual velocity), mobility, agility, and others. These elements are crucial for overall physical readiness and should not be overlooked (11).

One effective approach is to integrate the training of these skills within strength or endurance sessions. For example, mobility routines can be included at the beginning of the warm-up, agility drills can be incorporated at the end of the warm-up, short sprints can be added to the beginning or conclusion (depending on the session objective) of cardio sessions, contextual speed can be integrated into strength training circuits, and power can be developed by introducing a multi-joint power exercise at the beginning of the fundamental phase of the strength session. This microdosing approach, when applied consistently over time, can effectively maintain or develop these skills while still prioritising strength and endurance training.

References