Introduction

Since the era of the mighty Roman Army over 2000 years ago, military commanders have long understood the need to provision their soldiers with adequate nutrition (i.e. food and water). As such, nutrition and the military are fundamentally entwined.

Without a regular supply of food and water, no army can hope, or expect to successfully prevail in its principal role: war-fighting. Appropriate food, in terms of both quality and quantity, and adequate hydration are required to ensure that the physical capacity and mental performance of military personnel remain at optimal levels. The Roman Army’s longevity owed as much to its logistical organisation as to its discipline and fighting prowess.

Although this article will concentrate on the water aspect of nutrition (contemporaneously referred to as hydration), water and food coalesce under the banner of nutrition making it somewhat problematic to discuss the role of water without discussing the impact of food.

This article will initially present the Ministry of Defence’s (MOD) definition of nutrition and how it is framed with regard to physical fitness. The article will then present a brief historical overview of the military’s understanding of the importance of good nutrition, before then discussing current UK nutritional policy for military training and on operations.

The article will then look specifically at water and hydration within the military. It will present MOD policy and look at hydration and military performance. Finally, the article will discuss ergogenic aids and their potential impact on military performance.

Definition

In defining nutrition the MOD (2009, p.4-1) states:

“Nutrition is the science of food and the components of food that a living organism requires to maintain the processes of life. The complex chemical composition of the human body requires constant replenishment for the processes of energy production, tissue growth and repair and the bio-chemical functions of the human body.”

Nutrition in the Military

When looking at nutrition in the military the MOD (2009, p.4-1) states:

“Nutrition is an integral part of the physical fitness regime of the Armed Forces and will form part of the preparation for operational duties to ensure optimum fitness for task. Baseline standards for operational effectiveness are defined in the knowledge that theatre specific modifications can be readily achieved. The MoD has developed UK Military Dietary Reference Values (MDRV) for a range of macro- and micronutrients appropriate to the healthy end-user.”

The MOD (2009) also follows scientific convention that water is not classified as a nutrient but it is essential to the function of the human body. The MOD also notes that a large proportion of the body is made up of water and water is the medium in which many of the processes of the body occur, “It requires constant replenishment.” (MOD, 2009, p.4-2).

History of Military Nutrition

There are many examples in history that illustrate the impact of nutritional provision on the success (or otherwise) of military campaigns.

Scurvy was responsible for the loss of more sailors than enemy action in the eighteenth century. During Lord Anson’s circumnavigation of the world (1740-1744), 636 of 961 sailors in his fleet died (Booth, 1979). While serving as ship’s surgeon on board HMS Salisbury in 1747, James Lind, Royal Navy (RN), famously undertook the first prospective interventional trial, investigating the treatment of scurvy. ‘A Treatise of the Scurvy’ was published in 1753, recommending that citrus fruits were used to treat and prevent scurvy in the RN (Trohler, 2005). In 1776, Captain James Cook RN wrote in the Philosophical Transactions of the Royal Society that the addition of malt, sauerkraut and wild celery to the diet, along with strict adherence to cleanliness and a regular supply of fresh water aboard ship, meant that not one crew member succumbed to scurvy during the 3 year voyage of the Resolution (1772–1775) (Cook, 1776).

Preservation of food during long voyages remained a problem until 1800 when a French chef, Nicolas Appert, responded to Napoleon Bonaparte’s offer of a 12,000 franc reward for inventing a means of preserving food for the military. Appert used airtight glass containers, laying the foundation for pre-packaged food. This enabled the French Army to march long distances, carrying their own food, rather than having to rely on finding food along the way. One result of this was greater mobility, enabling the French Army to reach the battlefield before their opponent, engage in surprise attacks and to be frequently in better physical condition than the enemy (Forbes-Ewan, 1999).

Appert’s idea was further developed by Pierre Durand, a British merchant, who developed tin-covered iron canisters in 1810. Three years later, the British Army and the RN were supplied with food preserved in tin cans.

Napoleon is also credited with coining the phrase ‘an army marches on its stomach’. This mantra was dramatically highlighted during his failed invasion of Russia in the summer of 1812. Napoleon’s army numbered 600,000 soldiers. The ‘scorched earth’ policy adopted by the retreating Russians and the vast distances involved in resupplying food to the advancing front, allied to inhospitable weather conditions and dire sanitary conditions, meant that five months later the French were forced to retreat having lost 500,000 men to disease and starvation.

In the Crimean War, vast losses of life were caused by poor hygiene and inadequate nutrition. It took the intervention of two civilians to change the situation. Florence Nightingale and Alexis Soyer – also a French chef – collaborated to improve sanitation and restructure the provision of nutrition to the fighting troops and the sick (Nightingale, 1858; Cope 1959).

The military and health implications of soldiers’ nutritional intake on active service were well recognised (Robinson, 1905, p.378) by the turn of the last century: “the soldier who is well fed is not only in better bodily health and better able to resist disease, but he is more cheerful in difficulties and therefore more equal to any strain he may be called upon to endure”. It was also understood that feeding requirements of soldiers differed whether in barracks, at war or in hospital (Blackham, 1908).

More recently, nutrition on military operations has become a focus for research and investment. Problems with feeding soldiers in austere conditions are multi-factorial (Crawford et al., 2007, p.75), as seen during the Falklands War in 1982:

“During hostilities the main food supply was either the Arctic or the General Service 24 h ration pack; a significant number of troops did not eat all their rations with a consequent loss of weight and possible loss of efficiency. Reasons given for this failure ranged from ‘unappetising’ foods, shortage of time, nature of operations, and the lack of potable water with which to prepare the meal – particularly the Arctic ration.”

These issues remain a concern and have prompted ongoing research into military nutrition. The Arctic ration required a ready supply of water, readily available in snowy conditions but somewhat problematic elsewhere!

Contemporary Military Nutrition

Recent evidence supports the view that wider societal trends towards increased body mass and obesity are also prevalent in the armed forces, and could adversely impact upon operational capability (Nahgii, 2006; Wood, 2007; Roiz et al., 2008).

The armed forces represent an occupation with a required fitness standard on entry, a structured military fitness programme during phase-1, phase-2 recruit and officer cadet training and career-long fitness monitoring as part of the conditions of service.

This fitness requirement is supported in the three services through programmed exercise time as part of the working week, and access to remedial training packages for those personnel failing to achieve the required fitness standards.

Nevertheless, in more sedentary occupational branches of all three services, physical activity can be relatively easily avoided if the chain of command does not specifically monitor and sanction the required fitness levels in personnel. Concerns regarding the physical fitness, and associated exercise and nutritional habits, of recruits prior to the start of military training are presently being addressed through research collaboration between the RN and the Royal Air Force (Leiper et al, 2007). In 1999, The Defence Nutrition Research Centre of the Australian Defence Science and Technology Organisation conducted research which concluded that the mean daily energy expenditure of personnel varied from 12MJ (sedentary occupations) to 28MJ (special forces selection) per man (Forbes-Ewan, 1999). Recruits mean expenditure was 16MJ, those engaged in field exercise was 15MJ, jungle warfare was 19MJ and parachutists was 17MJ.

Current MOD nutrition provision and dining doctrine for duty military service personnel in barracks is described in the Joint Services Publication (JSP) 456, Defence Catering Manual (totalling 4 Volumes) (MOD, 2009, p.4A-1) – a policy document which states that the MOD “undertakes to provide military personnel with a basic knowledge of nutrition, with the aim of optimising physical and mental function, long term health, and morale”. To this end, it provides information on the roles and functions of dietary nutrients and refers to the Military Dietary Reference Values for guidance on appropriate macro- and micro-nutrient intakes (Casey, 2008).

JSP 456 forms the basis for the feeding provision that contracted caterers are required to serve within military establishments. As a catering manual, it also details advice for caterers in terms of examples of what might be provided; however, it is limited in terms of providing explicit evidence-based direction of what should be served. Indeed, JSP 456 is regarded as a minimum standard, rather than an optimum standard for feeding provision.

Further documentation in the form of JSP 404 (MOD, 1993) and Cesarani et al. (1995) provides detail to inform portion control. In terms of data quality and data applicability, the Military Dietary Reference Values (14) represent a mixed collection of standards drawn from varied sources (e.g. UK Department of Health recommendations, military and non-military nutrition research and US Nutritional Standards for Operational and Restricted Rations) (Committee on Medical Aspects of Food Policy, 1991; US Departments of the Army, Navy & Air Force, 2001).

Importantly, UK civilian population dietary guidelines (Committee on Medical Aspects of Food Policy, 1991) are based on sedentary individuals with the aim of promoting and maintaining good health through nutrition, while preventing ill health – standards are based on avoiding insufficiency rather than optimising sufficiency. Such guidelines may be applicable to some military personnel who do not undertake regular arduous physical activity and are engaged in a less active role, but would not be appropriate for personnel operating at high levels of physical activity for sustained periods of time (either during operations or training) and under challenging environmental conditions. For example, in 1999 The Defence Nutrition Research Centre of the Australian Defence Science and Technology Organisation conducted research which concluded that the mean daily energy expenditure of personnel varied from 12MJ (sedentary occupations) to 28MJ (special forces selection) per man (Forbes-Ewan, 1999). Further, military personnel may undertake arduous physical activity as part of:

• Structured preparatory training (i.e. for operational deployment or build-up for mandatory tests);
• Course training (i.e. Commando course);
• Mandatory tests (i.e. Combat Fitness Tests);
• As necessity dictates on operational deployment; and/or
• As part of their own personal training.

JSP 456 encapsulates the MOD’s nutrition policy, direction and guidance but has yet to be evaluated in terms of providing appropriate nutrition; this is particularly pertinent with reference to the Pay as You Dine (PAYD) menu policy. Originally proposed in 1975, PAYD was introduced in May 2005 as a means of helping to ensure financial equality (i.e. personnel only paid for what they ate) and reducing food waste (caterers were expected to provide for a minimum number of diners regardless of who actually ate). PAYD has been criticised in the national press for abolishing the previous system where all soldiers received three meals per day from the cookhouse, in return for a flat daily messing rate charge (Rayment, 2007; Wight & Basnett, 2009). Catering for military recruits and officer cadets during initial training, and for all operational units (e.g. Afghanistan), does not come under the PAYD system.

Inadequate nutrition can result in poor physical and cognitive performance (e.g. inability to carry out physical tasks, poor concentration and decreased vigilance) (Nicholas et al., 1997; Wilson & Morley, 2003). The long-term effects of both macro- and micro-nutrient imbalances include increased risk of vitamin and mineral deficiencies (potentially predisposing some individuals to an increased risk of stress fractures and rickets), obesity, hypertension, coronary heart disease, diabetes, osteoporosis and kidney failure. The implications of having a poorly nourished force may result in an increased risk of ill health (with associated medical-care costs), reduced manning levels owing to absenteeism and ultimately a reduced state of operational readiness.

The MOD has been pro-active in supporting healthy eating among service personnel through targeted educational lectures in phase-1 training, as well as the publication of nutrition guides (Messer et al, 2005; Casey & Wood, 2006; Casey & Wickes, 2007) and educational DVDs (Defence Food Services Integrated Project Team, 2007). The efficacy of such educational support has not been specifically evaluated, and indeed anecdotal evidence would support that ‘best-practice nutrition’ is not widespread among service personnel (especially during initial training) and off-duty calorie consumption, including alcohol, is more difficult to regulate.

Nutrition on Operational Deployment

On operations or on military exercises, if a field kitchen and fresh food are not available, UK military personnel subsist on Operational Ration Packs (ORPs) provided by their chain of command. The ORP, as stated by the UK MOD Nutrition Policy Statement (MOD, 2009, p.4A-1), is ‘designed to sustain troops on operations and during field exercises, with the aim of preserving life, preserving physical and mental function, maintaining mood and motivation, preventing fatigue and speeding up recovery’. The responsibility for the content of ORPs belongs to the Defence Food Services Team (DFST), part of Defence Equipment and Support, with scientific support from the Institute of Naval Medicine (INM), Alverstoke, UK, and the Defence Science and Technology Laboratory (DSTL), Porton Down, UK.

Operational nutrition has been the subject of recent media and political attention (Blackmore, 2008; Daily Hansard, 2010) and is of importance not only for health, but also for military efficiency and morale. Operational catering aims to ‘provide as near normal a diet as possible in all environments’ and a mainly ORP-based provision should be replaced by fresh rations after no more than 44 days (i.e. 14 days war-fighting and 30 subsequent days) (MOD, 2009, p.8-1).

The basic unit of the ORPs is the recently introduced Multi-Climate Ration (MCR), which replaced the previous 24 hour General Purpose (GP) ration pack. The MCR is designed to provide adequate energy and nutrients to sustain a soldier for 24 hours and comes in 38 different menu options, which includes six Sikh/Hindu variants, six Halal variants and six vegetarian variants.

lf all of the components of the MCR are consumed, it will provide a mean (across all variants) energy intake of 4098 kcal, which includes 651 g of carbohydrate, 130 g of protein and 92 g of fat. The energy and macro-nutrient profile of the MCR has been analysed (Wood & Curtis, 2008), and the utility of the MCR was reviewed by the INM (Fallowfield et al., 2009) against the Military Dietary Reference Values for hot-climate ORPs (Casey, 2008). The rations comprise a breakfast, a main meal and a pudding, snacks (trail mix, boiled sweets, energy bars and biscuits), soup and drinks (tea, coffee, chocolate and orange or lemon). All of the meals are packaged in aluminium foil laminate packets that can be immersed in hot water (boil-in-the-bag) to cook on hexamine stoves or can be eaten cold.

The 10-man ORP is designed to feed 10 men for a 24 hour period (or five personnel for 2 days); it requires field catering equipment and a chef (or someone trained with basic catering skills) to prepare one of the five menu variants. The actual nutrient quality and quantity, and the day-to-day variety, of the food prepared from the 10-man ORP is very much dependent upon the skill of the military field chef, and how the basic components of the ration are made into meals to sustain military personnel. The 10-man ORP contains some commercial components that can be adapted to vary the meals, which can also be supplemented with fresh food when available. A recipe book has been developed to help the field chef achieve the most from the 10-man ORP components (Defence Food Services Integrated Project Team, 2008).

There is a dearth of robust evidence supporting the nutritional adequacy of UK rations in terms of sustaining war-fighting. There is no published literature investigating change in body mass or body composition in soldiers eating ORP compared with fresh rations, or whether the ORP affects combat effectiveness. Work is presently ongoing to address this issue. The limited research available involved questioning users of the old 24 hour GP ORP, from which it was concluded that between 25% and 55% of the 24 hour GP ORP was discarded immediately on receipt and the most frequently discarded items were the snack items, which contained most (43%) of the energy (Messer, 2003; Casey & Messer, 2004).

Whether the contents of an ORP are consumed ultimately depends on the choices made by individual soldiers, but will be affected by numerous factors including palatability, weight of rations and load carriage considerations (soldiers currently patrolling in Afghanistan are, at times, carrying in excess of 50 kg), concurrent illness (especially diarrhoea and vomiting), altitude and environmental temperature, intervention of commanders and the tempo of operations (some personnel routinely enhance their ORPs with their own herbs, spices and other condiments).

MCR was introduced for soldiers in Afghanistan in 2009 following successful trials by the DFST involving the addition of hot-climate supplements to the GP ORP in 2007 and 2008. MCR was developed in response to problems encountered with the GP ORP (in particular menu repetition and unpopularity of certain items) with the aid of feedback from soldiers. MCR was also developed to be acceptable in a greater variety of climatic conditions. There is evidence to suggest that environmental heat increases energy requirements, but a far more pressing concern is the anorectic effect of a hot environment (Johnson & Kark, 1947; Herman, 1993). Thus, development of the MCR was, in the main, driven by the practical requirements of providing nutrition to a war-fighting population with the aim being to encourage eating (energy and nutrient intake) and drinking (hydration).

If a ration is not practical in terms of being readily consumed under hostile conditions or unpalatable under extreme environmental conditions, the nutritional content is largely irrelevant, as soldiers will be unable or unwilling to consume the contents, even if this is potentially detrimental to health (Johnson & Kark, 1947; Bean, 1968). From a duty of care perspective, the nutritional content of ORPs is also paramount – DFST has engaged with dietetics expertise to ensure that the energy and nutritional content is appropriate relative to current operational evidence, although the MCR is yet to be systematically evaluated within an operational theatre.

Studies from the United States of America in the 1980s reported conflicting evidence on whether US rations, called ‘Meal, Ready-to-Eat’ (MRE), resulted in body weight loss in an operational field setting (Friedl & Hoyt, 1997). In 1995, male soldiers who participated in a 30 day field study during which they were only provided with MRE rations lost 3.8% body weight, compared with a 1.2% loss in body weight in soldiers fed hot, cook-prepared meals (state of hydration was unaffected) (Thomas et al., 1995). Dual X-ray absorptiometry (DEXA) and anthropometric measurements indicated that the body weight loss was almost entirely fat mass, which was attributable to a reduced intake of carbohydrate, resulting in a net daily energy deficit of 600 kilocalories.

Nevertheless, it has been suggested that military performance may not necessarily be impaired in soldiers with body weight losses of 3-6% consuming operational rations for more than 10 days (Thomas et al., 1995). Recent evidence has suggested that providing food that can be readily snacked on throughout the day can improve physical activity during sustained arduous work (Montain et al., 2008). Thus, lighter, more nutrient-dense food items would be preferable in such a situation – the DFST is currently trialling patrol rations, specifically designed to meet this purpose (sweets in the ORPs would be combined to create a ‘nutty bag’ for this purpose).

The effect of operational nutrition and/or body weight loss on physical and cognitive performance is an area of intense research interest. Partitioning out these subtle outcomes from other stressors (e.g. sleep deprivation, cold, fear) is very challenging. This lends itself to questioning which (if any) performance areas or physiological parameters, apart from maintenance of body weight, operational nutrition should aim to influence, and how these parameters can be measured. There is also a growing body of evidence suggesting that caffeine can improve performance across a wide range of physical activities, as well as reducing fatigue and improving alertness (Burke, 2008). Caffeine has been shown to improve running performance and maintain vigilance during an overnight field operation for US Special Forces personnel (McLellan et al., 2005a & 2005b) and improve cognitive performance in sleep-deprived US Navy SEALS (Lieberman et al, 2002). However, it must be noted that both tea and coffee act as diuretics (i.e. they tend to increase the excretion of urine).

Early in 2010, the INM in collaboration with the Royal Centre for Defence Medicine (RCDM) commenced a study as part of the Surgeon General’s Armed Forces Feeding Project. This study will evaluate the inter-relationships between occupational energy expenditure, dietary intake, anthropometric measures, physical fitness, nutritional status and gut hormone concentrations in volunteer Royal Marines undertaking a six month tour of duty to Afghanistan on Operation HERRICK.

Measures were taken at four time points: pre-deployment; before and after mid-tour leave; and immediately post-deployment on the Marines’ return to the UK. These data will be used to address important military and medical questions concerning the possible physiological significance of changes in body composition and to clarify the specific nature of any body mass loss associated with an operational deployment (i.e. relative fat and lean tissue loss) and the reasons behind any such losses. The aims of this study are to provide evidence to support nutritional policy and advice for service personnel prior to and during operational deployments.

However, as noted earlier some personnel are employed in more sedentary occupational branches of all three services. Not all personnel will be employed in patrol or other war-fighting duties, rather they will be in low physical activity, but nonetheless, important support functions.

Water and the Human Body

As simple as it is, water plays a major role in every chemical reaction/process, which occurs in the body, it is the essence of life.

Water also stabilises the body temperature, carries nutrients to and waste away from the cells and is needed for cells to function. However, despite all these positives, water does not provide energy.

A loss of water will result in dehydration, which can decrease muscular strength and impair performance. A loss of 10% of body mass due to water loss can cause brain damage and death.

An individual’s daily requirement of water will vary due to the environment and dietary factors. For example, a high protein diet increases the requirement for water in contrast a diet containing a lot of fruit decreases the requirement.

A good indicator of hydration levels is the colour of individual’s urine, there should be 4-5 clear urination’s per day and at least 2-3 post training (although some researchers argue that it is only the morning urination that should be considered). An increased heart rate is another good indicator, particularly during exercise in hot environments. The feeling of thirst is a poor indicator of hydration levels, as by the time the sensation is felt the body is already partially dehydrated.

Participants in sporting activity should be fully hydrated before starting the activity and fluid should be drunk regularly during exercise. Where possible, drinking patterns should be incorporated into the training cycle and re-hydration should take place as soon, as is practical after exercise.

Studies featuring runners and cyclists have shown that drinking up to 900-1000 ml of fluid per hour is well tolerated.

The Research and Technology Organisation, a branch of NATO, suggests that soldiers can survive for extended periods with little or no food, and they can use supplements to meet their physical needs for even greater periods. However (RTO, 2009, p.7-23):

“Fluid replacement is the only way to avoid dehydration, reduce the risk of heat casualties, and thereby minimize military performance degradation. Water is the one item that the soldiers must have to remain combat effective; there are no alternatives.”

The MOD and Water Policy

The MOD (2009, p.8-16) states:

“The provision of an adequate and safe water supply is important for the maintenance of health and operational efficiency, and all water in the field must be regarded as unsafe unless obtained from an approved source or known to have been purified.”

The MOD (2009) directs that water should only be collected from approved water points, issued by Operations/Exercise staff once approved by medical staff. The Army (through the Royal Engineers) is responsible for providing potable water in the field to all Services in all theatres in both peace and war.

To discharge this responsibility the Army will normally set up water points at suitable locations to serve units in the locality. It is the unit responsibility to collect its requirements of water from the water points. When camps or expeditions are held in the UK, other than under field conditions, the parent unit (sponsor of the exercise) is to make arrangements for water supplies. During mobility exercises, when it is possible to collect water from a neighbouring mains source, a unit is to collect water direct.

The MOD states that the quantities of water required for domestic purposes for personnel in the field are dictated by the operational scenario, however the MOD states the following guidance should be considered:

1. Initial stages of an operation or for periods of intense operations: 10 litres per person per day;
2. Steady state for field conditions: 25 litres per person per day.
3. Steady state for Temporary Deployable Accommodation (TDA): 70 litres per person per day.
4. Steady state for well-found accommodation: 150 litres per person per day.

Calculations for the provision of domestic water requirements in the field should be used on the provision of 22.5 litres per person per day. In war conditions only, a reserve sufficient for 3 days at the rate of 6 litres per person per day is to be held at the field site to allow for disruption of supplies from the water points to units.

Water Availability: A Key Issue in the Field

Water availability during military operations affects the capacity of soldiers to carry heavy loads. Loads rapidly become unmanageable, and a significant contributor to this problem is the soldier’s need for water. As temperatures climb, the soldiers carry even more water to compensate for the loss of body fluids.

Water availability affects drinks packaging and design, re-supply operations and soldier load. Soldiers cannot be expected to carry weights greater than 50% of their body weight but it is very common. These weights have a negative impact on soldier endurance, situational awareness, and the ability to respond quickly and accurately to a threat.

A significant portion of this weight is attributed to the water that personnel are forced to carry. As a result armies have examined alternatives for supplying the soldier with water, in all environments, and across the full spectrum of operations.

Hydration and Military Performance

Perspiration dissipates excess body heat during exercise to assist in maintaining core body temperature. If this fluid is not replaced, dehydration can rapidly occur, leading to fatigue mental confusion and stress on the cardiovascular system.

Research (Forbes-Ewan, 1999) suggests that during infantry operations in hot/wet or hot/dry environments personnel may have a sweat rate of 1.0-1.5 litres per hour. However, sweating efficiency (a measure of the proportion of sweat that actually evaporates) differs between the two environments at 82% and 43% respectively. Any sweat that does not evaporate (drips as liquid from the soldier, or is retained as liquid in their clothing or equipment) represents wasted water; sweating leads to cooling only if the sweat evaporates.

Relative humidity (water vapour in the air) plays a part in a soldier’s temperature control. Soldiers engaged in operations in a hot/wet area will sweat profusely, but most of that sweat will be wasted and the body temperature will rise more quickly than in a hot/dry environment, where a higher proportion of sweat evaporates.  The US Army’s Ranger Handbook (2011, p.16-9) states “Your thirst mechanism will improve as you acclimatize to the heat, but you will still under drink if you wait until you feel thirst.”

Forbes-Ewan (1999) further suggests that it is common to find that military personnel, particularly ground troops, do not voluntarily drink enough to maintain a state of euhydration despite the availability of adequate water; a phenomenon known as ‘voluntary dehydration’ (Forbes-Ewan, 1999). A suggested method to overcome this is to schedule regular drinking times and ensure personnel are drinking appropriate rates to avoid becoming dehydrated.

Historically, personnel relied mainly on water bottles for the carriage and delivery of personal water. However, during operations in Afghanistan and Iraq, personnel started purchasing, at their own expense, commercially available systems (i.e. plastic tank and tube) that allowed them to drink water whilst moving and be hands free. After a period of time the MOD decided to purchase these systems for personnel.

In theory, such systems should encourage personnel to drink more because they no longer have to stop, lay down their weapon and direct their gaze away from their primary aid – looking for signs of the enemy – in order to drink.

Forbes-Ewan (1999) argues that when comparing water bottles to plastic tank and tube, the hydration status of personnel improved, although treatment effect did not reach statistical significance for any individual parameter and despite noting less cardiovascular strain (indicative of reduced severity of dehydration), no significant differences in thermal strain indices (such as heart, core or skin temperatures) where observed. Forbes-Ewan (1999) concluded that these systems have operational benefits over water bottles, are more acceptable to personnel and do not adversely affect hydration status or thermal strain. However, personnel still require water bottles for personal hygiene and cooking which may increase loads due to carrying two lots of water.

Finally, one of the major factors against heat illness is the maintenance of normal body water levels (that is maintaining euhydration). Hypohydration (a state of lower than normal body water) will adversely affect performance when hard work is conducted in the heat. The more severe the hypohydration (which is achieved by the process known as dehydration) the more severe are the symptoms. This occurs across a continuum, until, at high levels of hypohydration, heat-related illness (including life threatening heat stroke) becomes inevitable.

Hydration and Military Fitness Tests and Assessments

When conducting testing in warm conditions personnel are to be encouraged to drink 300ml (½ pint) of cold water 15-30 minutes prior to starting any testing or assessment and also to take fluids on completion.

In particularly hot and humid conditions the fitness instructor should initially consider whether testing would be better carried out in a cooler part of the day. Should testing be carried out in these circumstances, personnel must be given the opportunity to take in fluids along the route and be allowed to replenish fluids after the warm up if required.

Sports Drinks

Sports drinks can be used to re-supply carbohydrates as well as water, both during and after exercise. Water is absorbed even more quickly if it contains small amounts of glucose, sodium and potassium.

With endurance exercise (1 hour plus) there is often a need for carbohydrates as well as water. The body finds it difficult to absorb large quantities of water and sugar together (the higher the concentration of sugar, the slower the absorption rate). Drinks that contain 5-7% sugar are emptied from the stomach more slowly compared with water but do provide some carbohydrates.

These drinks are known as Isotonic and have the same nutrient concentration as blood. An ideal home-made isotonic drink can be made by diluting one part unsweetened fruit juice to two parts water and adding a very small pinch of table salt (to aid water absorption).

If more carbohydrates are required during long term exercise a stronger solution can be used. These are classified as Hypertonic as they have a higher nutrient concentration than blood. These are more suitable as post exercise recovery drinks as they can impair water absorption and increase short-term dehydration.

Ergogenic Aids

Ergogenic Aids (EA) are substances or techniques that lead to an improvement in one or more component(s) of physical fitness (Forbes-Ewan, 1999). However, the idea that eating particular diets or taking special substances may improve physical fitness is not new.

At the turn of the century athletes where trying substances such as desiccated liver, royal jelly, bee pollen, ginseng, B group vitamins, chromium picolinate and a host of other purported EA (Forbes-Ewan, 1999). The evidence for ergogenic effects is not strong for many of these purported EA. However, some substances and techniques are, genuinely, believed to be effective in improving athletic performance to the extent that some of them have been banned by the Internationa Olympic Committee because they give an unfair advantage to the user.

Promising EA, from a military viewpoint, include:

• Rehydration: methods of water delivery or formulations of beverage powder that encourage drinking, increase the rate of water absorption and retention within the body show promise as a means of improving endurance capacity.
• Carbohydrate Loading: this is a technique that has been used by marathon runners and triathletes for many years to improve endurance performance.
• Carbohydrate Supplementation: because of the importance of carbohydrate as the preferred fuel for muscular exercise, feeding supplementary carbohydrate to soldiers shows much promise as an effective method for extending the time to fatigue during arduous operations.
• Caffeine: this is a stimulant that occurs naturally in tea, coffee and coca products. Research demonstrates that caffeine can induce a significant improvement in endurance performance, although chronic usage has detrimental effects.
• Caffeine and Ephedrine: ephedrine is a naturally occuring stimulant derivesd from a Chinese plant (of the genus Ephedra). A combination of these two EA seems to have additive (or even synergistic) ergogenic effects on endurance capacity.
• Modafinil: this chemical was developed to treat a sleep disorder (narcolepsy). It shows considerable potential as an alternative to amphetamines for people engaged in sustained activities that involved sleep deprivation.
• Creatine: a component of muscle that provides ‘instant energy’ and is beleived to reduce recovery time between repeated bouts of anaerobic activity (e.g. sprinting).
• Blood Loading: a technique that involves taking a quantity of blood from a soldier, freezing it, and then reinfusing it shortly before the operation. This leads to elevated haemoglobin levels and hence improved aerobic performance.

Rehydration, carbohydrate loading and supplementation are perhaps of the greatest interest and value to military performance. Research since Forbes-Ewan suggests that some EA products may not provide the performance enhancements suggested (RTO, 2009).

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