An Cosantóir

25 FUELLING THE NATION Resting Metabolic Rate: RMR is the daily energy requirement of the body to maintain normal physiological functions. It can be calculated or measured in a number of ways, with indirect calorimetry, which measures the respiratory exchange between oxygen and carbon dioxide (Kenney et al 2015) being the most accurate. However, outside of a laboratory or elite setting this is highly impractical. I would personally use one of the many equations used to calculate RMR. The Mifflin equation (1990), simply requires input of weight, height, age, and gender. • Males: (9.99 x weight (kg)) + (6.25 x height (cm)) – (4.92 x age) – 161 • Females: (9.99 x weight (kg)) + (6.25 x height (cm)) – (4.92 x age) + 5. So, using a 30-year-old female, with a height of 175cm, weighing 65kg as an example: (9.99 x 65) + (6.25 x 175) - (4.92 x 30) + 5 = 1,601 kcal. Adding the thermic effect of food (TEF) at 10% = 1,761 kcal. Physical Activity: This is any energy expenditure outside of RMR and diet induced thermogenesis, and includes NEAT (unstructured basic daily activities), and EAT (planned, structured physical training or activity) (Chung et al 2018). Daily NEAT levels are generally greater than EAT and obesity can sometimes occur as a result of minimal NEAT. Physical activity can be estimated in a number of ways, some more detailed than others: Compendium of physical activities (Ainsworth et al 2011): A list of 821 different activities falling under 21 categories. Each activity is given a metabolic equivalent value (MET). 1 MET is the ratio of work metabolic rate to standard RMR (quietly sitting). It is measured as 1kcal/kg/hour. You multiply your weight by the MET value of a particular activity to calculate the energy expenditure for 1 hour. You can then multiply that figure by the time spent engaging in the activity to calculate the total amount of energy expended Example: Vigorous weight training session = 6 MET 60kg x 6 = 360kcal/hour. So, a 90-minute session would expend 540 kcal. As RMR is taken into account in the MET value, the time spent in the activity would have to be subtracted from 24 (as RMR accounts for a 24-hour period), and RMR for the remainder (22.5 hours) recalculated. This calculation hasn't taken into account any NEAT estimations, so any non-exercise activity (also listed on the compendium) would also need to be added. Physical activity level chart: A more practical, while less accurate, method of calculating physical activity. This involves a lot less maths. This chart would break activity into categories, and assign an activity value range to each: • Highly inactive: 1.4-1.6 • Moderately active: 1.7-1.99 • Extremely active: >2.4 So, again if our previous example was a moderate to highly active individual, we would multiply her RMR by 1.99. There are other more detailed charts, this is just one example. Total daily energy expenditure (1,601 x 1.99) + TEF @ 160 = 3,346 kcals. Nutrients: Not all calories are created equal, and while it is important to consume sufficient calories to meet daily energy requirements, it is equally as important to consume the necessary nutrients in the required quantities. Nutrients that the body requires to function optimally can be broken into two categories: • Macronutrients: Carbohydrate, Protein, and Fat • Micronutrients: Vitamins and minerals. Carbohydrate: Carbohydrate is an energy substrate that is ingested into the body through an individuals diet. Primary sources include grains, cereals, starches and fruit and vegetables. They can be either simple, or complex, and are categorised, as Hannon et al (2020) state, according to their glycaemic index, a numerical scale rating foods on their ability to raise levels of blood glucose, as well as their fibre content. 1 gram of carbohydrate can provide approximately 4 kcal. They are important for a number of reasons: • Primary fuel source for the glycolytic (anaerobic) system, which is the dominant energy system in extended high intensity efforts of up to two minutes, and consecutive shorter high intensity efforts, as well as being used as fuel for low intensity aerobic activities. Williams & Rollo (2015) write that an increase in muscle and liver glycogen stores prior to exercise will aid in delaying the onset of fatigue due to depletion, and the subsequent reduction in power output and work rate following prolonged intermittent efforts. • Recovery post training or operation. According to Hannon et al (2020), the ability of high G.I. carbohydrates to promote glycogen re-synthesis and rapidly elevate blood glucose levels, makes them preferable in the hours immediately following exercise. Thomas et al (2016) suggest an intake of 1-1.2 g/kg per hour during the early recovery phase in order to ensure optimal muscle glycogen resynthesis. • Carbohydrates are the sole fuel source for the brain and so, as Kenney et al (2015) state, severe depletion of carbohydrate can lead to negative cognitive effects. Therefore, insufficient carbohydrate availability could cause poor decision making or slower reaction Troops eating lunch on patrol, Liberia. Eating Finnish ration packs in Koukou-Angarana, Tchad.

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