Nutrition for Tactical Athletes: Insights, Applications and Research Gaps

Abstract

Tactical athletes, including military personnel, firefighters and rescue responders, operate in unpredictable and extreme environments that impose high physical and cognitive demands with life-and-death stakes. Tactical operations demonstrate metabolic demands akin to elite sports. Unlike sports competitions, tactical operations often involve prolonged exertion, limited food/water, disrupted recovery windows and circadian rhythms. This review draws on sports nutrition research to adapt evidence-based strategies for tactical athletes, highlighting key overlaps and distinctions. First, achieving adequate optimal energy availability in tactical athletes is challenging because of unpredictable demands, which makes it important to leverage training sessions to optimise nutrition strategies and energy availability. Second, when operational timelines are predictable, sport nutrient timing principles can be applied. However, under tight operational timelines, tactical athletes should aim for 1–4 g·kg⁻¹ body mass of portable, easily digested carbohydrates with fluids in the 1–4 h before deployment, guided by practicality, logistics and individual gastrointestinal tolerance. When operations are expected to involve moderate-to-high intensity activity within the first 2 h, lower fibre, lower fat and rapidly digestible carbohydrate forms (e.g. gels, sports drinks or soft bars) may be preferred to minimise gastrointestinal discomfort. In such situations, aggressive recovery and rehydration post-operation should also be prioritised. Under high environmental heat, high carbohydrate (≥ 7 g·kg⁻¹ BM) and low-FODMAP (Fermentable Oligo-, Di-, Monosaccharides and Polyols) intakes may mitigate heat-induced physiological changes, which include increased carbohydrate oxidation and appetite suppression. Last, evidence for creatine, nitrate, beta-alanine and bicarbonate in tactical athletes closely reflects findings in sport populations. The use of caffeine, however, requires more careful consideration as it may disrupt sleep.

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Key Points

Aggressive recovery (0.8–1.2 g·kg−1·h−1 of carbohydrates and 0.2–0.4 g·kg−1·h−1 of protein) with restoration of 100–150% sweat losses within practical limits are critical post-operation as redeployment may occur with little notice.

During extended wakefulness, consider low and frequent (0.3 mg·kg−1·h−1) or 2-hourly repeated dose (< 200 mg·dose−1 for up to 800 mg·day−1) for caffeine protocols.

For tactical athletes who are not heat acclimatised, high carbohydrate availability during hot extended operations can support increases in carbohydrate oxidation and appetite suppression. A low-FODMAP (fermentable oligo-, di-, monosaccharides and polyols) diet may reduce gastrointestinal discomfort, while pre-cooling with ice slurry can mitigate thermal strain.

Introduction

In 2024, the number of global emergencies requiring tactical athlete responses, such as floods, wildfires, earthquakes and armed conflicts, far exceeds the number of organised sports events. While hundreds of international sports competitions are scheduled throughout the year (including the Summer Olympics, FIFA Club World Cup, World Athletics Championships, Wimbledon), there were 393 recorded natural disasters in 2024, alongside multiple armed conflicts and civilian safety emergencies (e.g. fire rescue and law enforcement situations) [1, 2]. These crises demand a critical real-time intervention from military personnel, first responders and other tactical athletes. Unlike sports events planned months in advance, these emergencies are unpredictable high-stakes situations that highlight the indispensable role of tactical athletes on a global scale.

Tactical athletes, such as military personnel, first responders and law enforcement officers, share several physiological-related demands with sport athletes. Both groups endure rigorous training, strive to maximise physical performance and prepare for high-stakes events. As measured by doubly labelled water, the energy expenditure (EE) of tactical athletes ranged from 14.6 to 30.9 MJ (3504–7416 kcals)·day⁻¹ per day [3–8] and is comparable to sport athletes. This similarity underscores the need for strategic nutrition interventions to performance and recovery under variable operational scenarios. However, in an increasingly volatile and complex world, many governments foster contingency for a wide variety of overseas commitments. As a result, tactical athletes often deploy on short notice for extended operations under foreign geographical conditions [9]. Despite similarities in energy demands, tactical athletes therefore face unique challenges that differentiate their training and performance environment from sport athletes (Fig. 1).

Fig. 1.

Differences between sport and tactical athletes. This figure shows a comparison of sport and tactical athletes in operational, performance and recovery environments. Sport athletes (top right) operate under structured conditions with career-oriented competition stakes, optimal performance readiness and planned recovery. In contrast, tactical athletes face unpredictable environments with life-threatening survival stakes, sub-optimal performance readiness and limited recovery opportunities

For example, tactical operational scenarios are unpredictable owing to variable task durations, intensities, fuelling opportunities and high environmental temperatures. These complicate the accurate estimation of energy requirements and the implementation of precise nutrient timing protocols. Such operational challenges can have life-or-death consequences, as an inadequate nutrient intake impairs cognitive and physical capacity, leading to suboptimal performance status [10–14]. Moreover, tactical athletes often perform under sleep deprivation and disrupted circadian rhythms because of shiftwork and prolonged operations. All these further exacerbate performance challenges in such high-stakes environments.

Well-established principles of sports nutrition emphasise the role of nutrient timing and the strategic use of ergogenic aids to optimise performance. Yet, the application of these principles within the tactical athlete context remains suboptimal [15]. Research and recommendations for sport athlete health and performance also far exceed those available for tactical athletes, highlighting a notable gap in research tailored to the demands of tactical populations.

This gap in tailored recommendations for tactical populations becomes more evident when current obesity rates are considered. The prevalence of overweight and obesity vary by occupation, definition and geographical location. Reported rates range from < 1% in some military cohorts [16] to over 60% in certain firefighter and police cohorts [17–20]. In the USA, firefighter and police cohorts report combined overweight/obesity rates of 79–81% based on a body mass index (BMI) ≥ 25 kg/m², with obesity alone affecting 32–36% of individuals [17–20]. Among active-duty military personnel, obesity rates by BMI are similar across the Army, Air Force and Navy (27–30%), lower in the Coast Guard (24.2%) and lowest in the Marines (15.3%) [21]. International data highlight comparable statistics in Brazil, with ~ 69% of firefighters classified overweight/obese (by % body fat, BMI and waist circumference) [22]. Similarly, in Chinese military personnel, obesity prevalence was very low (0.3–0.6%) when using BMI > 24 kg/m² or bioelectrical impedance (> 22% body fat) [16]. While BMI can misclassify obesity when compared with body fat percentage or waist circumference [18, 23, 24], it remains a practical tool for cohort-level surveillance. Particularly in tactical cohorts where the prevalence of overweight/obesity is high, it suggests an accumulated mismatch between regular energy intake and EE over time [18, 24–28]. These tactical athletes are at a higher risk of injury, poor performance and premature career termination, especially in physically demanding roles [24, 29–32]. Diet quality is worse on shift days compared with rest days [33] and the limited availability of healthier food options during night operational hours complicates efforts to maintain optimal nutrition for health and operational performance [34–37]. Addressing these unique demands and challenges of tactical athletes therefore requires tailored nutrition strategies that optimise performance, reduce health risks and support career longevity.

This review aims to bridge these gaps by providing an overview of key sport nutrition strategies and considerations for tactical athletes. We examine how current sports nutrition recommendations can be adapted to meet the distinct needs of tactical athletes. Key considerations include adequate energy availability (EA), nutrient timing and the impact of high environmental heat stress and extended wakefulness due to prolonged multi-day operations. We also discuss the strategic use of sub-optimal EA status and time-restricted feeding (TRF) to decrease obesity. This review then identifies gaps in the existing literature for the tactical population and proposes directions for future research.

Search Strategy

Literature searches of studies published between 1988 and 2025 were conducted up to July 2025. They were conducted in PubMed, Web of Science, SPORTDiscus™ and Google Scholar. Keywords included ‘sport nutrition’, ‘performance nutrition’, ‘energy availability’, ‘energy expenditure’, ‘energy balance’, ‘military, ‘warfighters’, ‘special operations’, ‘police’, ‘law enforcement’, ‘firefighters’, ‘firefighting’, ‘athletes’, ‘carbohydrate’, ‘protein’, ‘shiftwork’, ‘circadian’, ‘extended operations’, ‘endurance’, ‘muscle performance’, ‘physical performance’, ‘aerobic performance’, ‘training’, ‘adaptation’, ‘diet’, ‘dietary’, ‘nutrition’, ‘metabolism’, ‘oxidation’, ‘immune function’, ‘glycogen’, ‘heat stress’, ‘heat acclimation’, ‘acclimatisation’, ‘supplements’, ‘ergogenic aids’, ‘caffeine’ and ‘time-restricted feeding’. Subject headings were used independently and in combination.

Eligible records included peer-reviewed human studies and the relevant grey literature published in English. Book chapters, conference proceedings, protocol papers and non-human studies were excluded. The initial database searches retrieved: PubMed (n = 7366), SPORTDiscus™ (n = 5091) and Web of Science (n = 12,933). For Google Scholar, only the first 800 results (ranked by relevance) were screened. After applying limits (English and relevant subject categories), excluding ineligible publication types, and removing duplicates, 851 records remained for title and abstract screening. Following a full-text review and backward citation tracking of included articles, 165 studies were included in the final synthesis.

Energy Demands and Challenges of Tactical Athletes

Adequate-optimal EA, recommended at > 40 kcal·kg⁻¹ fat-free mass (FFM)·day⁻¹, is essential for sustaining performance and preventing fatigue during tactical operations. Despite existing guidelines for macronutrient intake and adequate food provisions, tactical athletes often experience energy deficits of up to 30% during multi-day operations and training [5, 8, 10, 11, 38–40]. In these studies, FFM was not assessed but body mass (BM) losses of over 15% was reported, which indicates sub-optimal EA due to an inadequate energy intake [5, 8, 10, 11, 38–40]. During extended operations, the ability to achieve adequate-optimal EA is further complicated by a prolonged physical and metabolic load, logistical challenges due to insufficient time to prepare before deployment and harsh environmental conditions. For instance, tactical EE can vary from approximately 16 kcal·min⁻¹ for an urban counter-terrorism task [41] to 229 kcal·h⁻¹, under ambient heat conditions of up to 50.3 °C [42]. In both scenarios, the operational duration lasted 1 and 5 h, respectively. These metabolic demands drive overall tactical EE above 1000 kcals easily, even before accounting for the additional physiological and metabolic load of extreme environmental conditions [43]. These findings illustrate the substantial metabolic demands and energy cost of tactical tasks and the added difficulty of achieving optimal EA when compounded by real-world logistical and operational challenges. While tactical tasks are diverse, specific occupational roles at risk of sub-optimal EA include, but are not limited to, combat and rescue units engaged in multi-day operations with long work shifts, load carriage, limited resources and extreme environmental conditions (e.g. combat and special units for military and law enforcement, firefighters and disaster relief) [6, 7, 11, 39, 44, 45]. This underscores the need to leverage training sessions, where conditions are planned and controllable, to implement effective fuelling strategies and optimise EA.

By implementing proper nutrition strategies during training, tactical athletes can maximise adaptations and better prepare for the nutritional demands of real-world operations, which improves performance when it matters most. While acute negative energy deficits may not decrease performance [46], prolonged energy deficits have been associated with decreased power, physical and cognitive performance and poor health in tactical populations [10–14]. Addressing EA challenges through strategic planning and adaptive strategies is crucial for ensuring energy needs are optimised for high-intensity and/or extended tactical scenarios.

Estimating Energy Availability (EA) in Tactical Populations

In the context of tactical athletes, EA is defined as the amount of energy left for the body’s non-exercise functions after accounting for the energy expended during tactical activities. It can be calculated using the following formula [12, 13]:

$$\text{Energy availability}=\left(\text{energy intake}-\text{tactical}/\text{training energy expenditure}\right)/\left(\text{fat-free mass}\right)$$

While studies have investigated overall EE and energy balance in tactical athletes [5, 8, 10, 11, 38–40], the concept of EA differs from traditional energy balance calculations by focusing on the energy available for physiological processes beyond exercise [12, 13]. When energy intake does not sufficiently cover both exercise and non-exercise energy needs, a mismatch occurs [13]. This causes the body to adjust its non-exercise physiological processes to conserve energy [13]. Using the hypothetical example of tactical EE = 1000 kcal, Fig. 2 illustrates that the minimum energy intake to achieve optimal-high EA based on current EA classifications [13, 47] ranges from 3750 to 5200 kcals, depending on FFM. While estimating tactical EE during operations is challenging, training courses where activities are often pre-determined are useful opportunities to assess tactical EE and EA. These assessments may serve as eventual benchmarks for a more accurate EA estimation during tactical operations. Additionally, relative energy deficiency in sport (RED-S) symptoms may occur at higher EA thresholds in female tactical athletes and individual monitoring is warranted.

Fig. 2.

Classification of energy availability (EA) levels. This figure illustrates the classification of EA levels using a hypothetical tactical energy expenditure of 1000 kcal across varying fat-free mass (FFM) and energy intake values. The optimal-high EA range (depicted by larger circles) is achieved with an energy intake of approximately 3750–5200 kcal, depending on FFM. Optimal-High EA = a minimum of 40 and 45 kcal·kg FFM⁻¹·day⁻¹ for male and female respectively; Subclinical low energy availability (LEA) = 30–39 kcal·kg FFM⁻¹·day⁻¹for male and 30–44 kcal·kg FFM⁻¹·day⁻¹ for female; Clinical LEA = below 30 kcal·kg FFM⁻¹·day⁻¹ [13, 47]

Consistent with EA being conventionally expressed in kcal·kg FFM⁻¹·day⁻¹, the provision of sufficient energy in this section has been discussed relative to FFM. In comparison, current guidelines for other sport nutrition strategies (e.g. carbohydrate, protein, fluid and ergogenic aids) are expressed relative to total BM (g·kg BM⁻¹·day⁻¹). Accordingly, when referencing these guidelines in the subsequent sections, the units present the recommended intake per kilogram of BM unless mentioned otherwise.

Nutrition Strategies for Performance and Recovery

Tactical athletes often operate in environments with a damaged local infrastructure, which can limit food and fluid access. These include closed stores, disrupted supply lines and compromised clean drinking water. Therefore, tactical athletes should pre-position/carry portable and shelf-stable food options where possible. This lowers the risk of energy deficits and impaired fluid balance commonly associated with restricted food and fluid access, especially in extreme and hazardous environments [5, 8, 10, 11, 39, 40, 48].

Preparing for an Operation

Sport nutrient timing principles and planning can be applied under the following conditions [49–55]:

• when deployment time exceeds 2 h;

• well-defined operation duration and scenario;

• predictable time/interval to the next deployment.

Examples of appropriate sport nutrition strategies include supercompensation of glycogen stores with high carbohydrate intakes (7–12 g·kg BM⁻¹·day⁻¹) [49–51] and ‘protein loading’ with 40–100 g·day⁻¹ of protein [56]. However, amid unpredictable deployment schedules and operational scenarios, adapted sports nutrition strategies can be beneficial (Fig. 3).

Fig. 3.

Adapting sport nutrition to tactical nutrition. EAA essential amino acids, BM body mass, CHO carbohydrate, h hours

When preparation time is under 2 h, tactical athletes should prioritise easily transportable carbohydrates. Consistent with guidelines for sport athletes, a target intake of 1–4 g·kg BM⁻¹ is recommended where practical and logistically feasible [49–51]. If moderate-to-high intensity activity is anticipated in the first 2 h of operations, lower fibre and lower fat options are advised to minimise the risk of gastrointestinal discomfort [57]. Individual tolerance to specific foods and ingredients should be considered and tested during training sessions to confirm suitability and optimise the feeding strategy before operations.

Under short-term energy deficits (up to 6 days at 60% energy deficit), supplementation with 80 g of carbohydrates maintained steady-state aerobic performance [46]. Accordingly, portable and shelf-stable options should include easily transportable carbohydrate sources. Examples include gels, bars and drink powder, alongside high-energy snacks, meal rations, clean drinking water and oral re-hydration sachets. Beyond sustaining performance, carbohydrate supplementation also stabilises plasma sodium during high-intensity training [58] and increases the voluntary intake [59].

Despite established fluid intake guidelines for tactical populations with demonstrated efficacy to promote euhydration [60, 61], the risk of hypohydration remains a significant concern. This is especially true for firefighters, a well-studied tactical population in this area because of the inherent exposure to environmental heat stress as part of their job. More than 90% of firefighters are reportedly hypohydrated in the steady state [62], with 74.8% experiencing heat-related illness in a year [63]. Additionally, heat stress decreased functional balance and altered the perception of exertion, which led to an increased risk of injuries through slips, trips and falls in firefighters [64]. This emphasises the need for proactive hydration protocols focused on encouraging tactical athletes to understand the characteristics of their sweat rates in different tactical scenarios and drinking behaviour [65]. By doing so (e.g. during training courses), they can better strategise around potential sweat losses, assess the risk of hypohydration and identify opportunities for fluid replacement during different tactical operations [65].

Unlike carbohydrate recommendations, however, there is no benefit to overconsumption of fluids as body water cannot be effectively stored. Fluid intake should not exceed ~ 1.5 L·h⁻¹ or 12 L·day⁻¹, as the stomach empties less than ~ 1.5 L·h⁻¹ [60]. Exceeding this amount may result in bloating and a risk of hyponatremia [60, 66, 67]. Scenarios where drinking > 12 L·day⁻¹ is required are extremely rare. This should only be done if a 24-h urine assessment suggests inadequacy and must be accompanied by an appropriate electrolyte replacement [60]. Prior alcohol consumption should also be avoided, as it may cause diuresis and increase intestinal permeability [68, 69].

Fuelling During an Operation

Under tight deployment (or re-deployment) timelines, where insufficient carbohydrates (< 35 g of carbohydrates) were consumed in the 2 h leading to the operation, consuming carbohydrates with EAA (~ 6 g) can enhance performance, reduce muscle damage, maintain euglycemia and support glycogen re-synthesis [52]. Tactical athletes should target to consume carbohydrates at a logistically feasible rate during an operation. This could mean consuming about 80 g of glucose [46] throughout at practical intervals in an operation or 30–60 g per hour using a 6–8% carbohydrate-electrolyte drink or a gel every 10–15 min [70–74].

Recovering After an Operation

With redeployment timelines often uncertain, tactical athletes should prioritise aggressive recovery and rehydration [74–76]. Examples of such strategies include:

1. Carbohydrate-only refeeding: consume carbohydrates at a rate of 1.2 g·kg BM⁻¹·h⁻¹, prioritising sources with a high (> 70) glycaemic index.

2. Carbohydrate-protein combination: combine carbohydrates (0.8 g·kg BM⁻¹·h⁻¹) with protein (0.2–0.4 g·kg BM⁻¹·h⁻¹), including ~ 10 g of EAA.

3. Restore 100–150% of sweat losses within 1 h.

Given the practical challenges of limited time and potential discomfort, aggressive rehydration is best achieved through a fluid intake combined with food [77]. This can be done by consuming salty foods [77] with carbohydrate and protein content that complements the aggressive recovery recommendations mentioned above. As with all performance strategies, glycogen replenishment and fluid replacement protocols should be practised and fine-tuned during training, ensuring tactical athletes are prepared for the demands of their specific environments and missions.

The short-term recovery strategies mentioned in this section prioritise the demands of immediate redeployment and focus on macronutrient replenishment. Although military meal rations are designed to adequately provide for macro- and micronutrient needs, fuel supply/logistical challenges may still affect the nutritional status in tactical athletes during extended missions [8, 78]. Long-term recovery of tactical athletes should focus on correcting/preventing micronutrient deficiencies. In extreme cases, refeeding syndrome may arise after a prolonged energy deficit (i.e. prolonged starvation or very little nutritional intake for > 10 days). Tactical athletes at risk of refeeding syndrome should be identified to avoid or manage the condition appropriately [80, 81]. Examples of at-risk subgroups include captives, prisoners of war and victims of famine/food deprivation. Additionally, refeeding syndrome was also reported in a 26-year-old Marine recruit who underwent caloric restriction and strenuous training [79]. This highlights that an extended combination of energy deficit and high physical demands of tactical operations/training can predispose tactical athletes to the risk of refeeding syndrome [79]. Currently, there is no universal recommendation to advance a nutrition regime in a safe manner to minimise the risk of refeeding syndrome [80]. However, existing guidelines recommend 5–25 kcal·kg BM⁻¹·day⁻¹ depending on the risk, with a gradual increase of calories by 200–300 kcal every 3–4 days [80]. Close monitoring of electrolyte levels and fluid balance is crucial during this process to ensure optimal recovery of the tactical athlete [80].

Last, easily transportable carbohydrates are typically low in fibre. As such, the need to replenish energy quickly during phases of aggressive refuelling may compromise dietary fibre intake, digestive function and gut health. Therefore, long-term recovery nutrition plans should include dietary fibre targets for tactical athletes. In situations of prolonged low dietary fibre intake (< 20 g·day⁻¹), a gradual increase of intake to ~ 30 g·day⁻¹ (including ~ 2 g·day⁻¹ of beta-glucan) over a duration of 6 weeks is recommended [82]. This aligns with guidelines for sport athletes and can be incorporated into tactical nutrition planning when a recovery window of > 6 weeks is anticipated [82]. Examples of shelf-stable and operationally feasible beta-glucan sources include common cereals (barley, oats and rye) [81]. Assuming 4 and 6% composition of beta-glucan in barley and oats, respectively, a dose of 2 g can be obtained from approximately 35 g of barley and 50 g of oats [82].

Low-Carbohydrate High-Fat (LCHF) Diets for Tactical Performance

Since the early 1980s, low-carbohydrate high-fat (LCHF) diets have attracted interest, especially for their potential to improve performance in endurance events exceeding 4 h. By restricting carbohydrate availability, such diets increase the body’s capacity to oxidise fat, leveraging its large energy reserves to sustain exercise at intensities up to ~ 75–80% of peak oxygen consumption [65].

This metabolic shift, however, comes with trade-offs that are tactically relevant. When compared with training and competing with high-carbohydrate availability, 3–4 weeks of LCHF dietary adaptation was associated with significant detriments to high-intensity endurance performance [83]. This was because increased fat utilisation raised the oxygen cost of exercise, which reduces energy efficiency during high-intensity efforts (> 70% peak oxygen consumption) [83–85]. While it can be argued that the aerobic reserve may compensate for this trade-off at moderate intensities (< 70% peak oxygen consumption), individual responses to LCHF diets remain highly variable even at these intensities, with outcomes that range from performance impairments to enhancements [86]. Additionally, ketones appear as a potential alternative fuel to glucose in the brain during prolonged exhaustive exercise as cerebral ketone body utilisation increases at rest in response to carbohydrate restriction and/or elevated systemic ketone levels [87]. However, this hypothesis has yet to be experimentally tested in vivo in humans [87].

For endurance-focused tasks of low-to-moderate intensity with minimal need for rapid surge, explosive ability or cognitive precision, LCHF may offer situational viability especially when carbohydrate supply is logistically limited. In contrast, under high-stakes tactical activity that requires rapid bursts of high-intensity effort, sustained cognitive performance and adaptability to environmental stressors, LCHF will likely compromise performance. In these scenarios, the risk of compromised performance outweighs potential benefits. Additionally, despite 40 years of sustained interest, current evidence does not support a performance advantage of LCHF diets over established sports nutrition guidelines [86].

Nutrition Considerations During Operations with High Environmental Heat

In tactical operations with high environmental heat, multiple sources of heat can increase the metabolic demands in a tactical athlete—metabolic heat production from the physical demands (exertional heat strain) and heat from high ambient and radiant temperatures (heat stress). As heat stress increased, the effective performance of both complex decision making/action and routine tactical tasks decreased [9, 88]. While firefighters face inherent high environmental heat, the effect of heat stress is not limited to these tactical athletes. In flood rescuers, mean ± standard deviation oxygen consumption during a 60-min simulated rescue was significantly higher in warm water (31 ± 8 mL·kg⁻¹·min⁻¹) compared with cool water (10 ± 3 mL·kg⁻¹·min⁻¹) [48], highlighting the added metabolic strain and potential nutritional implications imposed by heat.

Exercise-based heat acclimatisation (HA) protocols, which occur over 5–14 days, are encouraged owing to their proven benefits in enhancing physical and psychological performance while reducing the risk of exertional heat illness under high environmental heat exposure [43, 77]. However, tactical athletes deployed at short notice often lack the opportunity to complete HA protocols, as operational demands may prioritise getting ‘boots on the ground’ to achieve immediate tactical objectives [9]. In such scenarios, unacclimatised tactical athletes are at risk of compromised operational performance as heat stress alters carbohydrate metabolism [89–92], appetite [93–97] and gut discomfort [98], all of which potentially impairs nutritional status and performance (Fig. 4).

Fig. 4.

Nutrition-related considerations of heat stress due to high environmental heat exposure. Potential strategies are highlighted in the outer ring

Earlier work by Jentjens et al. demonstrated that cycling in the heat (35 °C) reduces exogenous glucose oxidation and increases muscle glycogen reliance, which accelerates the depletion of muscle glycogen stores [90]. Even with facing airflow to maintain convective skin cooling, similar observations were reported [89]. Extending this understanding to tactical athletes, 90 min of walking under heat stress (37 °C) with load carriage elevates total carbohydrate oxidation and oxygen uptake [92], emphasising the heightened metabolic cost and cardiovascular strain under thermal stress. Therefore, while current sport nutrition guidelines for managing heat stress largely defer to sport nutrition guidelines [77], unacclimatised tactical athletes operating under high environmental heat will likely benefit from strategies that combat these nutritional implications. Key strategies include a high-carbohydrate diet [99], a low-FODMAP (Fermentable Oligo-, Di-, Monosaccharides and Polyols) diet [100], glucose-fructose co-ingestion during operations and a pre-cooling ice slurry [99, 100].

During single bouts of exercise performed under unacclimatised heat stress, a diet with 80% carbohydrates of total caloric intake improved time to fatigue [99]. For a tactical athlete weighing 70 kg, this exceeds the typical 45–65% acceptable macronutrient distribution range but is achievable when carbohydrate intake is ≥ 7 g·kg⁻¹ BM. However, persistent exposure to heat stress coupled with exercise can suppress appetite and therefore overall energy intake and availability [93–97]. Therefore, a high-carbohydrate diet may counteract heat-induced increased carbohydrate oxidation, elevated reliance on muscle glycogen and appetite suppression. When implemented before and during an operation, combining this strategy with a low-FODMAP diet may further help minimise gastrointestinal discomfort caused by heat stress [100].

To combat reduced exogenous carbohydrate oxidation during extended operations in heat stress [89, 90], tactical athletes should prioritise co-refuelling with glucose and fructose combinations as they utilise distinct intestinal transporters and metabolic pathways. Research on glucose-fructose combinations during prolonged exercise in the heat has demonstrated increased exogenous carbohydrate utilisation [91] and performance under heat stress [101], supporting its effectiveness in optimising energy delivery and performance in tactical athletes. However, heat stress elevates circulatory epinephrine at the muscle, which promotes increased muscle glycogenolysis and inherent intracellular accumulation of glucose-6-phosphate [102]. Therefore, fructose helps to improve carbohydrate availability by bypassing the glucose-6-phosphate pathway [103]. In tactical athletes considering carbohydrate intake ≥ 7 g·kg⁻¹ BM or glucose-fructose combinations for operations in high environmental heat, gastrointestinal discomfort caused by delayed gastric emptying or malabsorption may be exacerbated by heat stress aforementioned [57]. Therefore, gut training is also recommended to minimise associated discomfort and inconveniences. For comprehensive guidance on gut training, readers are referred to the review by Costa et al. [57].

For tactical athletes adopting HA protocols, a comprehensive review of nutritional considerations is well covered by Rosbrook et al. Notably, much of the existing research on HA has focused on the fluid-electrolyte balance, with macronutrient requirements remaining underexplored. Prolonged high-intensity HA protocols can reduce appetite, increase glycogenolysis, deplete muscle glycogen stores and induce endocrine changes that affect EA during recovery [43]. These changes include decreased testosterone and insulin-like growth factor levels, as well as elevated cortisol, which may further compromise EA and hinder physiological adaptation [13, 14, 43]. Therefore, while current carbohydrate recommendations during HA protocols stand at 5–8 g·kg⁻¹ BM [43], there may be a need for increased energy and/or carbohydrate intake to achieve adequate EA in the days after extended periods of heat stress or HA protocols to promote recovery.

Last, ice slurry consumption before and during exercise is a well-studied internal cooling strategy for athletes training or competing in high heat conditions [104–106]. In tactical athletes, ice slurry consumption delayed elevation of the body core temperature and improved work capacity for up to 30 min [107, 108]. Initially used in industrial applications, ice slurries are an efficient “heat sink” to absorb and dissipate heat through three key properties: (1) high energy storage density due to the latent heat of fusion of its ice crystals; (2) fast cooling rate from the large heat transfer surface area created by its numerous particles; and (3) consistent low temperature during the cooling process, with a higher heat transfer coefficient than water or other single-phase liquids [109, 110]. As it is a homogenous mixture of small ice crystals and carrier liquid [109], such as water or sport drinks, it may also benefit tactical athletes by serving as a fluid source to minimise fluid loss when the sweat rate rises in hot ambient conditions.

Ergogenic Aids for Performance Enhancement

Several ergogenic aids have demonstrated potential to enhance performance in tactical athletes. Caffeine, the only stimulant approved by the US Department of Defence, has strong evidence in improving mental alertness and mitigating fatigue [111]. Beta-alanine, creatine and beetroot juice have been shown to improve physical performance in active military personnel [112], supporting outcomes such as increased endurance and muscular strength. Sodium bicarbonate, when used as an acute supplement, enhanced glycolytic capacity [113] and reduced obstacle course completion times in military pentathletes [114], indicating its effectiveness in high-intensity short-duration tasks. These findings mirror current evidence in sport athletes for improving performance across various events [65, 115]. By adapting these evidence-based protocols from athletic research, tactical athletes can strategically optimise their performance to meet the physical and cognitive demands of their operational environments. Examples of possible tactical scenarios for four ergogenic aids (creatine, nitrate, beta-alanine, bicarbonate) are summarised in Fig. 5, with caffeine elaborated separately below owing to its impact on sleep.

Fig. 5.

Enhancing tactical performance with ergogenic aids using sport athlete parallels from Burke et al. [65]. s seconds

In addition to ergogenic aids with well-established evidence, ketone monoesters (KME) have gained recent interest. This stems from preliminary evidence that exogenous ketones mitigated declines in cognitive performance after intense exercise [116, 117]. Laboratory studies further suggest that KME improves blood and muscle oxygenation [118] and cognitive performance [117] under hypoxic conditions and metabolic stress, which are attractive benefits to tactical athletes who are involved in high-altitude operations. Despite these promising findings, the effects of KME remain inconsistent across tactical populations. In special operation forces personnel, consuming 26.7 g of commercially available KME drink (26.7 g of KME, deltaG Tactical; TdeltaS Global, Inc., Orlando, FL, USA) failed to enhance physical or cognitive performance in a mountaineering operation training [119]. Similarly, a 0.5 g·kg⁻¹ BM dose of KME did not reduce the rise of salivary stress markers or improve performance in firefighters [120].

Caffeine

Current caffeine guidelines for sport athletes by the International Olympic Committee recommend 3–6 mg/kg BM (210–420 mg for a 70 kg individual) consumed 60 min before an event [115]. However, in tactical populations, it is important to balance caffeine with the most restorative role of sleep as extended wakefulness and disrupted circadian rhythms are common [111]. Despite its ergogenic benefits, it is the most overused supplement in the military [111]. Excessive daily intake (three or more energy drinks, equivalent to ~ 240 mg of caffeine) among US service members in combat environments such as Iraq and Afghanistan resulted in disrupted sleep following night operations, which impaired recovery sleep after extended total sleep deprivation [121, 122], increased daytime sleepiness and an increased risk of accidents [123]. Additionally, caffeine ingestion in hot environments may increase susceptibility to exertional heat stress, with an intake at 3–10 mg·kg BM⁻¹ associated with increased body core temperature of 0.2–0.6 °C [124–128] or 0.10 °C·h⁻¹ [129]. While such increments are modest and unlikely to independently precipitate an exertional heat illness, they narrow the physiological safety margin in hot and humid or uncompensable environments [127].

Therefore, the direct application of caffeine recommendations for sport athletes is limited for the tactical population as the operational contexts for tactical athletes should be considered. These include duration of prior wakefulness, the time remaining until the next sleep opportunity and environmental stressors such as heat [124, 130–135]. To translate existing evidence into practice, Table 1 provides guidance for dose adjustments under different considerations.

Table 1.

Guidance for caffeine dose adjustments under different tactical considerations

Consideration	Guidance	Notes
Duration of prior wakefulness: extended wakefulness (18–72 h) requiring sustained vigilance or mitigation of cognitive decline	Several dosing regimes have shown efficacy in attenuating performance impairment during nocturnal wakefulness: • Low-dose, frequent intake (0.3 mg·kg−1·h−1) [136] • 200 mg every 2 h (800 mg·24 h−1) [135, 137–141] • Single 300-mg dose [139, 142] • Slow-release 600 mg·day−1 [121]	Tolerance develops with habitual use [143] No improvement observed for marksmanship accuracy [138, 139, 144]
Time remaining until the next sleep opportunity: at least 8 h away	At least 12 h away: pre-workout supplement (~ 217.5 mg) consumed ≥ 13.2 h before bedtime [143] At least 8 h away: coffee (~ 107 mg per 250 mL) [143]  < 8 h away: consider < 100-mg dose with glucose [135, 145, 146]	Inter-individual sensitivity not accounted for [143]
Heat exposure (high WBGT/hot environment)	Limit caffeine intake to ≤ 3 mg·kg BM−1·day−1 or consider smaller (1–3 mg·kg BM−1) split doses [124–129]	Studies reviewed were conducted in controlled laboratory or field settings with ambient temperatures up to 50 °C [124–129], but occupational exposures (e.g. firefighting [147–149]) can exceed this

h hours, WGBT wet bulb globe temperature

Ergogenic Aids for Operations Under Heat Stress

A comprehensive meta-analysis by Peel et al. showed that the effects of ergogenic aids on body core temperature and sweating responses varied greatly when consumed in hot environmental conditions. Their work extends earlier discussion on caffeine under heat stress and highlights the potential of taurine and GABA to lower heat strain for tactical athletes operating in hot environmental conditions [131]. An acute intake of 50 mg·kg BM⁻¹ of taurine before exercise in the heat induced an earlier sweating onset, a greater sweating rate and a lower body core temperature [131]. Similarly, despite reducing heat dissipation, consuming 1 g of GABA directly before heat exposure (at rest or exercise) appeared to increase heat storage capacity, which may benefit short-term heat exposure as heat gain is reduced [131].

Of the four ergogenic aids listed in Fig. 5, creatine, nitrate and sodium bicarbonate had sufficient eligible evidence for a pooled analysis of their effects on body core temperature and sweating responses in a hot environment [131]. Creatine supplementation alone did not appear to influence body core temperature [131]. However, combining creatine with glycerol for pre-exercise hyperhydration slowed the rise in body core temperature during constant-load exercise in the heat [131, 150], which can be useful for tactical athletes operating under heat stress. Nitrate and sodium bicarbonate supplementation, however, did not improve thermoregulation [131]. The endurance and blood pressure benefits of nitrate supplementation also appeared diminished under heat stress [131].

Nonetheless, sodium bicarbonate supplementation may still benefit tactical athletes operating in hot environments as it has been shown to delay central fatigue under heat stress. A dose of 0.3 mg·kg BM⁻¹ mitigated heat-induced increases in minute ventilation, elevated arterial partial pressure of carbon dioxide and improved cerebral blood flow [151]. Separately, sodium bicarbonate has gained recognition for its potential to reduce the risk of developing acute kidney injury during physical work in the heat [151–154]. This is because acute kidney injury is often associated with acidosis and sodium bicarbonate is administered to correct the acid–base imbalances [155]. While it successfully improved the buffering capacity, sodium bicarbonate did not influence markers of kidney injury in firefighters [153].

Last, menthol use is often highlighted for enhancing performance in hot environments as it improves thermal comfort, thermal sensation and work rate in the heat [156, 157]. It creates a cooling sensation by activating cold receptors TRPM8 (transient receptor potential melastatin-8) [158], but it does not actually lower body core temperature as it does not remove heat from the body. This is supported by Peel et al., who observed a non-significant decrease in peak body core temperature [131]. True cooling requires heat loss through processes such as melting (latent heat of fusion, e.g. through an ice slurry) or evaporation (latent heat of vaporisation, i.e. through sweat evaporation), which absorb significant heat from the body. For example, ice melts by absorbing heat (334 J·g⁻¹), and sweat evaporates by drawing even more heat (2400 J·g⁻¹) [77]. As menthol involves no such phase change or energy transfer, it improves thermal comfort but does not reduce body core temperature. As a result, current evidence showed no meaningful decrease in body core temperature [156, 159]. This means body core temperature may continue to rise, leading a tactical athlete to feel cooler than they are. This creates a potential risk of overexertion beyond safe limits especially during extended tactical operations that involve prolonged exposure to high environmental heat and complicated reactions or decision making [88]. Therefore, it is crucial to remain cautious and monitor body core temperature closely during menthol use in tactical athletes, where possible in appropriate simulated training prior to actual use in real-life operations. This is because the perception of cooling from menthol may not accurately reflect the body’s true heat stress, potentially increasing the risk of a heat-related illness.

Addressing Obesity and Metabolic Risks

Maintaining optimal EA should be the priority during training for optimal health and operational readiness. Given the unpredictable nature of tactical operations, traditional sport periodisation plans designed around targeted peak and competition seasons are impractical. For tactical athletes with excess adiposity especially, incorporating intentional phases of subclinical LEA with close monitoring LEA is a possible strategy to achieve weight loss and a performance-enhancing physique if necessary. Within the controlled environment of training courses, including this strategy in a nutrition plan offers relevant tactical athletes a structured approach to reach their goals when required [47]. For these tactical athletes, a potential strategy includes a periodised nutrition plan with deliberate periods of “train high” and “rest low” [160] (Table 2).

Table 2.

Example of a periodised nutrition plan for tactical athletes with deliberate periods of “train high” and “rest low”

Day	Training focus	Training load	Nutrition strategy
Monday	High-intensity sessions (twice a day, above ventilatory/lactate threshold)	High	Train high: High EA
			Protein: 1.6–2.0 g·kg BM−1·day−1
Tuesday	Resistance training (strength)	Moderate	Train high: Moderate-high EA
			Protein: 1.8–2.4 g·kg BM−1·day−1
Wednesday	Rest or light-intensity recovery session	Low	Rest low: Lower EA with TRF (e.g. 3 g·kg BM−1·day−1 of carbohydrates, 8 a.m. to 4 p.m. eating window)
			Protein: 1.8–2.4 g·kg BM−1·day−1
Thursday	High-intensity sessions (twice a day, above ventilatory/lactate threshold)	High	Train high: High EA (carbohydrate-loading pre-run, recovery carbohydrate + protein post-run)
			Protein: 1.6–2.0 g·kg BM−1·day−1
Friday	Resistance training + core work	Moderate	Train high: Moderate EA
			Protein: 1.8–2.4 g·kg BM−1·day−1
Saturday	Low-intensity endurance training	Low	Rest low: Lower EA with TRF (e.g. 3 g·kg BM−1·day−1 of carbohydrates, 8 a.m. to 4 p.m. eating window)
			Protein: 1.8–2.4 g·kg BM−1·day−1
Sunday	Active recovery (e.g. yoga, mobility)	Low	Rest low: Lower EA
			Protein: 2.0–2.4 g·kg BM−1·day−1

BM body mass, EA energy availability, TRF time-restricted feeding

“Train High” and “Rest Low”

“Train high” refers to ensuring optimal-high EA around key training sessions, which maximises performance and recovery. Such sessions typically involve a high cardiovascular/resistance training load or programmes designed to enhance pathways of oxygen-independent glycolysis and carbohydrate oxidation [161]. This can be paired with “rest low”, which refers to periods of lower EA or subclinical LEA outside of training, thereby creating windows of caloric deficit to optimise BM/composition. The readers are directed to well-written reviews [49, 50] for more information on carbohydrate periodisation. During the lower EA phases, an adequate/elevated protein intake (1.6–2.4 g·kg BM⁻¹·day⁻¹) is crucial to support muscle protein synthesis, preserve lean mass and mitigate the risks associated with LEA [160]. Additionally, TRF can be considered to align the nutrient intake with circadian rhythms, further enhancing metabolic efficiency and supporting weight management. However, close monitoring is necessary as the risks of aggressive energy restriction alongside high physical demands can extend beyond impaired performance and RED-S [11]. In rare cases, they may contribute to complications such as refeeding syndrome (illustrated in an earlier case study [79]).

Time-Restricted Feeding (TRF)

Time-restricted feeding, where food intake is confined to a 6–12 h window each day, focuses on the timing of food intake rather than calorie restriction in traditional dietary interventions. This makes it a practical and feasible approach for tactical athletes facing the unpredictable demands of shift work [34, 162]. It has been shown to improve cardiometabolic health and performance in tactical athletes [34, 162–164], thereby mitigating possible circadian misalignment due to shift work and irregular feeding hours. For instance, an 8-week TRF intervention (14 h fasting: 10 h eating) in a small sample of firefighters working irregular shifts resulted in reduced inflammatory markers (interleukin-6, interleukin-1β), lower cortisol and reduced C-reactive protein levels [163]. When combined with resistance training, TRF may further improve favourable outcomes for body composition and metabolic health [165]. However, most TRF studies in tactical cohorts to date are limited by small sample sizes and observational or pilot designs, and findings should therefore be interpreted cautiously. Integrating TRF with training periodisation principles (e.g. “train high, rest low”) remains a promising, though still exploratory, strategy to optimise performance, recovery and body composition. An example of how this can be conceptualised with sport nutrition targets for carbohydrates and protein is shown in Table 3 below.

Table 3.

Example of a high- and low-EA nutrition plan combined with “train high” and “rest low” within a time-restricted feeding protocol (14-h fasting, 10-h feeding window)

10-h feeding window		Higher EA diet combined with “train high”			Lower EA diet combined with “rest low”
Time	Time	Food/training	Carbs (g)	Protein (g)	Food/training	Carbs (g)	Protein (g)
6 a.m.	8 a.m.	Bread (120 g, 4 slices)	60		Rest or light-intensity recovery session
		Semi-skimmed milk (300 mL)	15	10
		Peanut butter (2 tablespoons, 36 g)	8	8
		Strawberry jam (2 tablespoons, 30 g)	30	–
8 a.m.	10 a.m.	Morning training session: high intensity			Bread (60 g, 2 slices)	30	–
					Semi-skimmed milk (300 mL)	15	10
					Peanut butter (1 tablespoon, 18 g)	4	4
					Strawberry jam (1 tablespoon, 15 g)	15	–
11 a.m.	1 p.m.	Greek yoghurt (200 g)	10	10	Greek yoghurt (200 g)	10	10
		Granola (50 g)	35	5	Banana (60 g)	15	–
		Apple (150 g)	20	–
1.30 p.m.	3.30 p.m.	Jasmine rice (250 g)	75	7	Jasmine rice (180 g)	50	7
		Grilled chicken (120 g)	–	27	Grilled chicken (150 g)	0	34
		Frozen mixed vegetables (200 g)	15	3	Frozen mixed vegetables (200 g)	15	3
3 p.m.	5 p.m.	Banana (60 g)	15	–	Apple (150 g)	20	–
		Energy bar (50 g)	30	–	Semi-skimmed milk (300 mL)	15	10
4 p.m.	6 p.m.	Afternoon training session: high intensity			Rest or light-intensity recovery session
6 p.m.	8 p.m.	Pasta (300 g)	90	12	Pasta (180 g)	50	12
		Domino tomato pasta sauce (125 g)	15	1	Domino tomato pasta sauce (125 g)	15	1
		Minced beef (120 g)	–	27	Minced beef (150 g)	–	34
		Frozen mixed vegetables (200 g)	15	3	Frozen mixed vegetables (200 g)	15	3
		Total	413	118	Total	269	128
		Estimated g·kg BM−1 for 75 kg BM	5.51	1.57	Estimated g·kg BM−1 for 75 kg BM	3.59	1.71

BM body mass, Carbs carbohydrates, EA energy availability

Research Gaps and Future Directions

While significant progress has been made in understanding the unique nutritional needs of tactical athletes, several key gaps remain. First, much of the current research has focused on military and firefighter populations, with notably fewer studies conducted in law enforcement/police officers. Given the distinct physical and operational demands of each tactical group, more targeted research in law enforcement populations is essential to fully address their specific nutritional requirements.

Second, there remains a clear need for research to refine dietary strategies that support both performance during sub-optimal states and recovery afterwards, as these conditions are inevitable in tactical settings. Future work should prioritise more precise assessments of tactical EE to improve estimates of EA across diverse operational contexts. In addition, studies are needed to evaluate targeted macronutrient supplementation strategies during prolonged physical exertion, particularly when compounded by sub-optimal EA and environmental stressors such as high heat.

Third, the application and effectiveness of ergogenic aids to tactical settings across different operation settings (e.g. extended operations with sleep disruption to load carriage and logistical restrictions in an extreme environment) and the potential impact on safety and feasibility is limited. With existing evidence on creatine, beta-alanine, and other ergogenic aids derived largely from controlled laboratory studies or athletic contexts, future research should evaluate commonly used ergogenic aids across a spectrum of tactical scenarios, with particular attention to acute performance benefits, safety and feasibility to inform decision making.

Last, the high prevalence of overweight and obesity in some tactical groups indicates that existing nutrition guidelines are not being effectively translated into practice. The next critical research gap, therefore, is understanding how tactical athletes can be supported to adopt nutrition recommendations across different contexts using behavioural change frameworks. This is a gap acknowledged in sports nutrition and also remains understudied in tactical populations. Future research should prioritise: (i) identifying barriers and facilitators of behavioural change in both deployed and non-deployed settings; (ii) adapting and evaluating behavioural change techniques from studies conducted in sport athlete or shift workers; and (iii) developing scalable approaches to track adoption and assess long-term impacts on health and performance outcomes.

Conclusions

In tactical environments, the adage “train like how you operate” underscores the critical importance of consistency between training regimes and operational performance. For tactical athletes, this principle is vital for ensuring that the high standards established during training are maintained under the unpredictable and demanding conditions of real-world operations. Just as tactical athletes practise drills and tactics repeatedly, they should consistently apply their nutrition strategies during both training and operations. Nutritional consistency during training fosters adaptation, which is crucial for operational success. When tactical athletes adhere to a well-planned dietary regime that mimics operational demands, they facilitate physiological and psychological adaptations that improve their readiness for actual missions. This consistency helps to optimise metabolic responses and enhances the body's ability to handle the physical and cognitive stresses of tactical environments.

Funding

No funding was received for the preparation of this article.

Declarations

Conflict of interest

Jamie Lye Ching Ting and Jason Lee Kai Wei have no conflicts of interest that are directly relevant to the content of this article.

Ethics approval

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Code availability

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Author contributions

JLKW conceived the idea for this review. JLCT conducted the literature search and selected the articles for inclusion in the review. JLCT wrote the first draft and contributed to the figures and tables. JLCT and JLKW revised and edited the original manuscript. Both authors read, edited and approved the final version.