089 - Fuel, Fire, and Form: Unlocking the Physiology That Drives Tactical Performance
Tactical performance is driven by how efficiently the body produces, uses, and recovers energy. Every sprint to cover, every stair climb in gear, and every prolonged carry is fueled by internal systems that determine how long you can last and how quickly you can recover. When those systems fall behind, performance breaks down fast.
This chapter explains how the body supplies energy through three primary systems: phosphagen, glycolytic, and oxidative. It connects each system to real tactical work—short explosive movements, repeated high-intensity tasks, and long-duration operations. It also describes how these systems adapt to training, how they decline with inactivity, and what is required to maintain capacity over time.
More importantly, this chapter helps you match training to demand. It explains why athletes gas out during work-to-rest mismatches, why energy crashes mid-mission, and why recovery is often mismanaged. Tactical athletes are not bodybuilders or endurance specialists. They need rapid access to power, sustained output, and the ability to repeat efforts with minimal loss in performance.
Understanding energy systems is not academic. It is essential. If your conditioning plan does not reflect the energy demands of the job, it is not preparing anyone for what matters. This chapter gives you the physiological foundation to build programs that work in real conditions, not just controlled environments.
What the Chapter Covers
This chapter details how the body produces energy and how that process changes in response to training. It introduces the three energy systems(phosphagen, glycolytic, and oxidative) and explains when each system is dominant based on task intensity and duration.
The phosphagen system provides immediate energy for high-intensity, short-duration tasks like breaching, sprinting, or lifting heavy loads. It relies on stored ATP and creatine phosphate and is depleted quickly, usually within 10 seconds. The glycolytic system kicks in next, supporting repeated efforts or moderate-duration tasks lasting up to two minutes. It produces energy through the breakdown of glucose, resulting in byproducts like lactate that influence fatigue. The oxidative system supports sustained, lower-intensity activity by breaking down carbohydrates and fats in the presence of oxygen. It is essential for long-duration work like rucking, patrolling, and extended response efforts.
The chapter also explains how these systems adapt to training. For example, repeated sprint efforts improve phosphagen recovery. High-intensity intervals increase glycolytic capacity and buffering. Steady-state aerobic work improves oxidative efficiency and mitochondrial density. Each system adapts to overload in different ways and on different timelines.
In addition to system function, the chapter addresses physiological adaptation. It covers how muscular, neural, and hormonal systems change with consistent training. This includes improved stroke volume, increased enzyme activity, better substrate utilization, and enhanced energy efficiency.
The final sections address detraining and maintenance. It explains how quickly different systems decline with inactivity and what training volume is needed to maintain adaptations when regular training is disrupted. This is especially important for tactical populations who often face unpredictable schedules, deployments, or injury recovery.
What This Means:
Tactical athletes are not built for one energy system. They need all three functioning together, with the ability to shift between them under pressure. When the job demands explosive output, followed by sustained movement, followed by rapid recovery, the body must have the fuel systems to match that pace. If training does not reflect those transitions, performance will fall apart at the exact moment it needs to hold.
This chapter breaks the myth that “cardio is enough” or that “more strength fixes everything.” Tactical readiness is powered by energy availability. If your athletes can’t recover ATP fast enough, they will slow down. If they can’t clear lactate efficiently, fatigue will set in early. If their aerobic base is too low, they will never recover between efforts, and small tasks will feel harder than they should.
Every energy system adapts at a different rate and responds to different inputs. A few sprints won’t build aerobic capacity. Steady-state runs won’t improve repeat sprint ability. Without precision, conditioning becomes random effort with no lasting effect. This chapter helps you understand what you are really training, and how to adjust based on performance gaps you see in the field.
You cannot expect tactical professionals to function in high-threat environments if their energy systems are untrained or mismatched to the work. Movement begins with muscle, but performance is sustained by bioenergetics. If you want to improve output, start by improving the engine.
Tactical Implications:
Match conditioning to operational demands: Use the energy system most aligned with the task. Sprint-based conditioning trains the phosphagen system. Intervals target glycolytic adaptations. Long-duration efforts build the oxidative base needed for recovery and endurance.
Program for system integration, not isolation: Real-world scenarios require rapid transitions between energy systems. Train mixed efforts like gear-loaded sprints into prolonged carries or high-rep tasks under fatigue.
Use recovery markers to guide conditioning: Monitor heart rate recovery, breath control, and repeat effort quality to assess energy system readiness. These are better indicators than simple work volume.
Maintain base fitness during downtime: The oxidative system declines quickly with inactivity. Use low-volume, moderate-intensity sessions to preserve endurance when time or resources are limited.
Adjust expectations during sleep deprivation or stress: Fatigue, poor sleep, and high cortisol blunt energy system performance. Program deloads or prioritizes low-intensity movement on high-stress days to avoid compounding burnout.
Questions To Consider:
Are you deliberately training all three energy systems, or just defaulting to what feels hard?
Does your current conditioning program reflect the stop-and-go nature of tactical work, or is it overly focused on one type of effort?
How do you assess whether your athletes are recovering properly between repeated efforts or training sessions?
What systems are breaking down first under pressure—explosive output, sustained work, or recovery?
When mission readiness is disrupted by injury, travel, or duty, do you have a plan to maintain energy system adaptations?
Miller MG. Physiological adaptations and bioenergetics. In: Alvar BA, Sell K, Deuster PA, eds. NSCA’s Essentials of Tactical Strength and Conditioning. Human Kinetics; 2017:45-63 .