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ABOUT THE AUTHOR

Jayden Azzopardi is the Manager and Head Coach at Botany Fitness, a strength and conditioning facility in Botany, NSW, Australia, and a co-founder of Train AERO, a digital fitness programming application. He holds qualifications as a ASCA Level 2 Coach, CrossFit Level 2 Trainer, Weightlifting Level 2 Trainer (Burgener Strength), Concept2 Certified Instructor, and Certified Conditioning Coach (Bioforce). With over seven years of active coaching experience across strength, conditioning, Olympic-lifting and functional fitness, his current work focuses on athletic development for youth and community-level athletes. He has spent time in Rugby League high performance units, is a 2021 and 2023 CrossFit Games Semi-Finals Athlete, and a 2023 Madrid Championships Elite Individual competitor.

INTRODUCTION

Flag football is a sport built on speed. Played in a 5-on-5 format on a field approximately 50 yards long by 30 yards wide, across two halves of 15 to 25 minutes, the game produces roughly 40 to 60 offensive snaps per team (3,1). Each play lasts between four and eight seconds. Players cover an estimated 800 to 1,200 metres of high-intensity running per game through maximal accelerations, sharp directional changes, and high-velocity sprinting (1). Given that profile, coaches have historically built their programs almost entirely around speed, power, and anaerobic capacity. That thinking is not wrong. It is just incomplete (3).

The aerobic system gets left out because coaches fear it will slow their athletes down. That concern deserves to be taken seriously – and it will be addressed directly later in this article. But removing aerobic conditioning from the program entirely is like baking a cake without eggs. It might come together in some form. But it will not mix or cook properly. The structure will not hold. At some point, usually in the third or fourth quarter of a close game, it falls apart.

Building an athlete’s aerobic base is the equivalent of laying the concrete foundation before the rest of the house goes up. A coach can invest in a quality kitchen, premium windows, and expensive finishes. But without the foundation, none of it holds. Speed, power, and skill all sit on top of the aerobic base. Neglect the base and those qualities will not survive the full duration of a game, regardless of how well they were developed in the gym.

Flag football made its Olympic debut at the 2028 Los Angeles Games, raising the stakes for athlete development at the youth level (7). Whether the sport retains its place at Brisbane 2032 will depend on the success of LA28 and the decision of the host organising committee. The standard of preparation for young athletes must reflect those ambitions. A player who is electric for a quarter and a half before the tank empties will not compete at that level.

The purpose of this article is to outline the physiological role of aerobic base conditioning in sustaining repeated sprint ability (RSA) and agility in youth flag football athletes, and to provide practical guidelines for integrating it into a weekly training structure.

THE PHYSIOLOGY OF REPEATED SPRINT ABILITY

To understand why aerobic fitness matters in a speed-dominant sport, look not at the play but at the gap between plays. In flag football, a maximal sprint of approximately six seconds is typically followed by 20 to 40 seconds of recovery before the next snap (3,4). That cycle repeats 40 to 60 times across a game. The physiological burden of that pattern is substantial and it accumulates.

Each sprint draws almost entirely on stored phosphocreatine (PCr) to generate adenosine triphosphate (ATP). PCr stores are limited and substantially depleted within the first six to ten seconds of maximal effort. What restores them is oxygen. PCr resynthesis is an aerobic process (4). Research indicates approximately 50% of PCr is restored within 30 seconds, but full restoration requires two to three minutes of aerobic metabolism (4). In a game where the next snap arrives well before that window closes, an athlete’s aerobic capacity determines exactly how much PCr is available when the ball is snapped again.

A simple diagnostic used in practice with fatiguing athletes is to ask them one question: are your legs heavy, or is it your lungs? The answer tells you a great deal. Heavy legs point to a peripheral limiting factor – the musculature is struggling to produce force. Lungs point to a central one – the cardiovascular system cannot deliver oxygen fast enough to support recovery between efforts. In youth flag football athletes with an underdeveloped aerobic base, the answer is almost always the lungs. As the game progresses and PCr stores fall short, the athlete shifts to the anaerobic glycolytic system. Hydrogen ions accumulate. Intramuscular pH drops. Peripheral fatigue accelerates (5). What coaches observe on the field is a player who was explosive in the first quarter becoming visibly heavy-legged in the fourth.

The relationship between aerobic fitness and RSA is well established in the literature. Tomlin and Wenger (7) demonstrated a significant positive correlation between VO2max and the ability to recover from high-intensity intermittent exercise, finding that athletes with greater aerobic capacity recovered markedly faster between repeated sprint bouts. Aerobic training is not junk volume for a speed-based sport. It is the mechanism by which speed becomes repeatable across a full game.

Consider Noah. An athlete with an Oz Tag and basketball background, Noah came into flag football with exceptional natural ability – elite plyometrics, electrifying acceleration over 30 to 40 metres. His sport history had been built almost entirely on short, explosive efforts. Shooting jump shots. Short sprints in Oz Tag. He had never trained for sustained output. When an aerobic session was first introduced into his program – a 30-minute Zone 2 block, deliberately easy by design – he lasted about five minutes before he was done. Not from a lack of effort. He simply had no capacity to pace himself across that kind of duration. He had never needed to. The discomfort was real and so was his resistance to it.

Around weeks four and five he started to understand how to pace. He could stay in the session longer and began to recognise what the right effort felt like from the inside. He still did not enjoy it particularly. But he stopped fighting it. By the eight-week mark, when sprint testing was re-run over 40 metres, the stopwatch showed something clear. His top-end speed had not dropped. What had changed was his consistency across repeated efforts. He could produce the same times across a full set of sprints that previously would have seen him fade by the third or fourth rep. The aerobic work did not limit his potential. It removed the ceiling on it.

To give coaches a concrete target: elite male flag football and field-sport athletes at the international level are expected to achieve VO2max values of approximately 55–62 mL/kg/min, while elite female athletes typically fall in the range of 48–55 mL/kg/min (2). In field-based terms, a well-conditioned U18 male athlete should target a 2 km time trial of approximately 7:00 to 7:30 minutes. A U18 female athlete should target 8:00 to 8:30 minutes. These numbers reflect an aerobic capacity sufficient to maintain PCr resynthesis across the full volume of competitive play.

AGILITY, NEUROMUSCULAR FATIGUE, AND INJURY RISK

Agility in flag football is not just physical. Reading a defensive alignment, processing it, deciding, and executing a sharp cut at speed, all within a fraction of a second, demands the central nervous system (CNS) is functioning properly. Fatigue degrades this at every level.

As an athlete tires, CNS output drops and local muscular control deteriorate. The ability to decelerate efficiently through a change of direction goes first. Coaches see it clearly – the trunk comes upright, the knees stiffen, the hips stop dropping. Agility performance falls and injury risk rises sharply. Non-contact ACL tears and ankle sprains become significantly more likely under these conditions (6). In adolescent athletes whose neuromuscular systems are still developing, that risk is higher still.

A developed aerobic base delays the onset of both central and peripheral fatigue. It preserves the neuromuscular efficiency required for precise movement late in the game. Aerobic conditioning in this context is not just a fitness tool. It is an injury prevention strategy, and the two goals are not in competition with each other.

PRACTICAL APPLICATIONS

Knowing aerobic conditioning matters is one thing. Programming it for a developing U18 athlete without undermining the rest of the program is another. Two things must be understood before any methods are applied.

The first is the interference effect. High volumes of aerobic training carry a documented risk of blunting top-end speed, suppressing fast-twitch fibre recruitment, and reducing explosive power adaptations (8). This is why elite sprinters avoid sustained aerobic running. For flag football athletes, the volume must be kept low enough to stimulate aerobic adaptation without crossing into territory that costs speed. One dedicated aerobic session per week is the right starting point for most athletes in a team environment. A coach who tells you aerobic work will make their kids slower has probably been running too many sessions, or running them too hard. The answer is not to remove the sessions. It is to dose them correctly.

The second issue is specificity. Rowing, skiing, and cycling are effective cardiovascular stimuli but they do not replicate the movement demands of sprinting. The aerobic adaptations they develop may not transfer to running performance with full efficiency. The elliptical trainer, which closely mirrors the reciprocal limb action of running at significantly reduced ground-reaction force, offers better movement-pattern transfer and should be the first choice where access allows (8). The Concept2 RowErg, SkiErg, and BikeErg are strong alternatives.

What is worth adding, for coaches working with youth teams, is that the erg environment produces outcomes beyond the physiological. A typical team based conditioning session at Botany Fitness starts with banter. The group talks about the weekend game – what went well, what did not, what they are going to fix. There is a light stretch, some discussion about technique on the machine, then the work begins. The challenge is keeping athletes in Zone 2 rather than racing each other. They have learned over time what that effort feels like, but the competitive instinct does not disappear. Sessions are structured around pairs or small groups, often pairing players who need to build chemistry on the field. A quarterback and a running back working through a 40-minute erg block together builds something that is hard to manufacture through drills alone. It is also the first time many of these athletes have been exposed to ergometer training at all.

The technique demands of the RowErg or SkiErg engage a different part of the brain. Learning a new skill in a training environment, even one unrelated to the sport, reinforces coachability. That carries over.

1. Extensive Tempo Running

Extensive tempo running is the most sport-specific aerobic tool available for flag football athletes. Sub-maximal runs at 65 to 75 percent of maximum velocity develop aerobic capacity while reinforcing relaxed, efficient sprint mechanics. The athlete should feel in control throughout. Rhythmic, not racing.

Table 1. Sample Extensive Tempo Running Protocol (Pre-Season, Week 1)

This intensity avoids significant lactate accumulation and CNS fatigue while driving the capillary density and mitochondrial biogenesis that underpin aerobic recovery capacity. The relaxed mechanics also double as active recovery work, promoting blood flow and tissue healing. Tempo running sits best on lower-intensity days or as an early warm-up block during the general physical preparation (GPP) phase.

2. Off-Feet Ergometer Conditioning

For athletes carrying lower-limb fatigue, or during phases where running volume is already high, off-feet ergometer conditioning delivers a full cardiovascular stimulus with minimal mechanical load. The elliptical is the preferred tool. The Concept2 RowErg, SkiErg, or BikeErg are effective alternatives.

Table 2. Sample Off-Feet Ergometer Conditioning Protocol (GPP Phase)

The athlete should be able to hold a conversation throughout. If they cannot, the intensity is too high. This session works as both an aerobic development tool and active recovery – particularly effective placed the day after two consecutive high-intensity sessions.

3. Integration into the Weekly Training Structure

Placement matters as much as content. An aerobic session the day before a maximal speed session will compromise the speed session. The structure below reflects a conservative aerobic volume – two sessions per week – designed to develop the base without touching the speed and power qualities the sport demands.

Table 3. Recommended Weekly Training Structure for U18 Flag Football (Pre-Season)

Wednesday’s session does two jobs: it builds aerobic capacity and serves as active recovery following the back-to-back demands of Monday and Tuesday. Saturday’s tempo block is low enough in intensity that Friday’s RSA session is unaffected, and it reinforces the relaxed mechanics that transfer directly to competitive play.

This structure is a starting point. Individual athletes will respond differently. An athlete who already carries a strong aerobic base may benefit more from additional rest as competition approaches. An athlete who is visibly fading in the back half of games may need a short block where aerobic development takes priority, even if that temporarily costs a small amount of top-end speed. If that athlete is still fast enough to compete but can now sustain their output across a full game, that is a win. Program the biggest limiting factor first.

CONCLUSION

There is a version of coaching flag football that produces athletes who look outstanding in the first half and fall apart in the second. They are fast, they are powerful, and they have been trained almost exclusively for those qualities. The aerobic system was never touched because the coach feared it would make them slower. The result is a player whose speed is real but not repeatable – a highlight reel that runs out of footage by the third quarter.

The aerobic base is what makes speed last. It is what allows an athlete to produce the same 40-metre time on snap 45 as they did on snap one. Without it, everything else a coach has built will eventually give way, usually at the worst possible moment in the game.

One session per week is enough to change that. Done correctly, it will not slow athletes down. It will not blunt their power. What it will do is give them a foundation strong enough to hold up everything that has been built on top of it. The protocols in this article require nothing more than a grass field and an ergometer. They are accessible, straightforward, and grounded in the physiology of how the body recovers between maximal efforts.

Elite male U18 athletes should target a VO2max of approximately 55–62 mL/kg/min and a 2 km time trial of 7:00 to 7:30 minutes. Female athletes should aim for 48–55 mL/kg/min and a 2 km time trial of 8:00 to 8:30 minutes. These are not aspirational numbers. They represent the aerobic capacity required to maintain explosive performance across 40 to 60 repeated sprint efforts in a competitive game.

Build the foundation. Everything else will hold.

REFERENCES

1. Bishop, D., Spencer, M., Duffield, R., Lawrence, S. The validity of a repeated sprint ability test. Journal of Science and Medicine in Sport. 4(1): 19-29. 2001.
2. Buchheit, M., Laursen, PB. High-intensity interval training, solutions to the programming puzzle. Part I: cardiopulmonary emphasis. Sports Medicine. 43(5): 313-338. 2013.
3. Gabbett, TJ. The training-injury prevention paradox: should athletes be training smarter and harder? British Journal of Sports Medicine. 50(5): 273-280. 2016.
4. Girard, O., Mendez-Villanueva, A., Bishop, D. Repeated-sprint ability – part I: factors contributing to fatigue. Sports Medicine. 41(8): 673-694. 2011.
5. Glaister, M. Multiple sprint work: physiological responses, mechanisms of fatigue and the influence of aerobic fitness. Sports Medicine. 35(9): 757-777. 2005.
6. Hewett, TE., Myer, GD., Ford, KR. Reducing knee and anterior cruciate ligament injuries among female athletes: a systematic review of neuromuscular training interventions. Journal of Knee Surgery. 18(1): 82-88. 2005.
7. Tomlin, DL., Wenger, HA. The relationship between aerobic fitness and recovery from high intensity intermittent exercise. Sports Medicine. 31(1): 1-11. 2001.
8. Wilson, JM., Marin, PJ., Rhea, MR., Wilson, SM., Loenneke, JP., Anderson, JC. Concurrent training: a meta-analysis examining interference of aerobic and strength exercises. Journal of Strength and Conditioning Research. 26(8): 2293-2307. 2012.