31st March 2016
One of the major determinants of success in endurance events is an effective and personalised nutrition strategy both in training and competition. An athletes diet also affects their health status and the 50+ athlete must factor into their nutrition program additional challenges such as changing hormone levels, rising cholesterol levels, rising blood pressure and deteriorating arterial integrity as well as changes in bone quality, skeletal muscle mass and cognitive function. Macro and micro nutrient intake must also reflect the changing nutritional demands over the year.
This article will address the nutritional issues facing the 50+ endurance athlete and how a correct nutrition strategy can improve training quality, lower race times and assist post-workout/event recovery.
Carbohydrate (CHO) is stored in the body in muscle tissue and the liver with a small amount present circulating in the blood. An 80kg man with a well-balanced diet might store about 500g of CHO. This is stored as glycogen within muscle tissue and accounts for about 400g, the liver stores about 100g of glycogen and circulating glucose accounts for about 3g. That equals about 2,000kcal of stored CHO.
You could choose to keep topping up your CHO by taking endless gels, bananas and flapjacks BUT, and this is a very, very important BUT, the average human being can only process about 60 grams of CHO an hour. If you are burning 700kcals an hour tackling the London Cycle Sportive your 60g of CHO is only providing 240kcals which means a 460kcal deficit.
Unless you are a new kind of super-fat-adapted athlete you cannot make this deficit up with contributions from fat alone so you must ensure, before you ride or run, that you have sufficient CHO stored and you can do this by eating correctly in the days leading up to the event then, during the event, make sure you are replacing the used carbs by topping up regularly but not by more than around 60g per hour otherwise performance can be negatively affected by severe gastro-intestinal (GI) distress. Athletes can maximise their CHO processing by training their gut, indeed some have successfully ingested up to 120g of CHO an hour. By taking in glucose, referred to as a single transportable CHO, when training, athletes can enhance the ability of the gut to transport glucose molecules across the gut membrane by increasing the amount of glucose transporter proteins available. Sports science research has shown that by adding fructose to a glucose based sports drink i.e. moving from a single to a multiple transportable CHO, delivers more CHO to the muscles per unit of time. Adding Sodium facilitates transmission of the CHO across cell membranes creating an even more effective sports drink.
A recent breakthrough is CHO mouth rinsing. Research using time-trial specialists given a 6.4% solution of CHO as a mouth rinse (NOT swallowed) showed they improved their scores against a same taste artificially sweetened drink and neuroimaging of the brain shows that mouth rinsing with a CHO solution activates certain reward and motor control regions in the brain. Unidentified receptors in the mouth sense CHO leading to changes in corticomotor excitability which can reduce perception of effort. This is useful if an athlete has taken on the upper limit of CHO in the gut and swallowing more would lead to GI distress. Using a CHO mouth rinsing strategy can benefit training as reduced perception of effort can leading to increases in training load without the additional calories.
Proteins are found in every cell in the human body and are responsible for a wide array of hormonal and metabolic activities including fighting infection, carrying oxygen and muscular contraction. Protein is also an essential component in the construction and repair of cells and tissue e.g. the giant protein Titin is responsible for the integrity of muscle fibres and is known as a structural protein whilst the hormone Insulin is a signalling protein and Amylase is a functional protein found in saliva and responsible for the chemical process of digestion. Protein requirements will vary over the year if you are following a periodised training plan with a range from about 0.8g.kg.day-2g.kg.day as mentioned earlier in this article.
Proteins are made up of Amino Acids (AA’s). Some AA’s we can synthesize ourselves and these are known as nonessential AA’s, some we can synthesize but not very efficiently and these are known as conditionally essential AA’s and the remaining AA’s we cannot synthesize and they are known as essential AA’s. Dietary proteins are classed as complete or incomplete depending on the value of the EAA’s contained within. Most animal proteins are classed as complete and all vegetable proteins are incomplete. Proteins that contain all the EAA’s and in large amounts are classed as high-quality proteins and those that do not contain all the EAA’s and/or have them in very small amounts are classed as low-quality proteins. Without sufficient EAA’s in the diet the body will start to catabolize or break down muscle tissue.
Certain age related hormonal changes also lead to a loss in muscle-mass therefore it is essential to maintain adequate levels of protein intake in concert with an individualised resistance training program in order to maintain skeletal muscle mass. The Protein Digestibility-Corrected Amino Acid score (PDCAAS) is the best internationally recognised method of quantifying protein value in the diet. A PDCAAS score of 1 means the food source provides all the necessary EAA’s and in sufficient quantity. Eggs, fish and milk are excellent sources with but the highest PDCAAS scoring food sources are the supplements Whey and Bovine Colustrum although certain brands vary in quality.
During off-season when hypertrophy and strength are program goals as precursors to power training there is an obvious need for additional protein. However extra protein is also required during high-intensity training, such as in preseason, when there are successive bouts of interval training, e.g. Lactate Threshold training or Functional Threshold Training. On these occasions there is greater demand for protein both in terms of metabolic fuel provision and in terms of muscle fibre recovery. During a resistance training phase, whether it is strength or power, recovery is accelerated and protein and glycogen synthesis is enhanced if protein is added to a carbohydrate drink. Research in 2006 and 2008 by Beradi et al. found that cyclists completing 60 minute bouts of best-effort time trial pace performed better and recovered quicker having consumed a PRO+CHO mix compared to CHO only. In 2013 Hill et al. found that ingestion of a whey protein and CHO mix improved the certain adaptations to endurance training, including muscle protein synthesis, in Triathletes and Cyclists.
A quick look at my Garmin Edge 810 bike computer informs me that during my last ride I used 2,282kcal. Had I gone anywhere near depleting my carbohydrate stores in order to meet this demand then I would have felt extremely uncomfortable and may have needed medical attention. In some cases complete glycogen depletion can result in death from associated hypoglycaemia. Even allowing for carbohydrate supplementation at feed stations it is evident that body fat stores do contribute to cycling, running and swimming performance including my 2,282kcal usage. Since our fat stores are many times more plentiful than our CHO stores it would make sense to use as much of them as possible during each event.
When we exercise intensely we tend to use more and more CHO and less and less fat. As our fitness improves we can train more intensely and we can train for longer and if we have trained very efficiently then we can train harder and longer by using fat as the main substrate, the main fuel source. By reducing CHO intake and increasing FAT intake it is possible to encourage the body to produce more enzymes and carrier-proteins involved in FAT metabolism. As with many physiological processes some are counter-intuitive, e.g. increasing seed oil intake does not encourage ‘FAT adaptation’ but instead saturated fat intake, such as animal fats, does. More importantly becoming a FAT adapted athlete takes time and requires a lot of commitment, there is no room for having the weekend off your low-CHO diet, let alone a croissant on a Sunday, as your daily CHO intake will only be between 50-150g.kg.day-1 and that must include fruits and vegetables! For those of us not following a fat-adapted lifestyle FATS are still and essential part of the diet.
FATS are involved in daily hormonal processes, building cell membranes and internal structures, transmitting nutrients across cell membranes and enabling proper function of the nervous system. Certain FATS have an anti-inflammatory effect, some have an anti-depressive effect and others have an anti-catabolic effect and play an important role in maintaining skeletal muscle mass. However not all FATS are the same. FATS are classified according to their chemical structure and small changes in bonding between the hydrogen, carbon and oxygen molecules, as well as the length of the molecular chain that makes up each fatty acid, can have vastly different effects on the human body. The 2 main categories of FATS are SATURATED and UNSATURATED. Both are essential for optimal health. Unsaturated fats are classified further as either MONOUNSATURATED FATTY ACIDS (MUFA) or POLYUNSATURATED FATTY ACIDS (PUFA). Some polyunsaturated fats are known as HIGHLY UNSATURATED FATTY ACIDS (HUFA) such as the fish oil fatty acids eicosapentanoic acid (EPA) and docosahexanoic acid (DHA). As a population middle-aged people in the UK do not consume sufficient EPA (omega 3) or DHA (omega 3) for optimal health. This population also does not consume sufficient quantities of certain PUFA’s such as linolenic acid (omega 3) but over consumes other PUFA’s such as linoleic acid (omega 6). This is important for the middle-aged endurance athlete as overconsumption of Omega 6 acids can have an inflammatory effect which can exacerbate conditions such as arthritis, diabetes, heart disease and other chronic diseases whereas Omega 3 acids have an antiinflammatory effect and can combat the low-grade inflammation bought about by intense endurance exercise. Some research suggests that conditions such as bursitis, tendinitis, osteoarthritis as well as ‘over-training’ syndrome can be alleviated with the correct dose of Omega 3 supplementation. Hydrogenated, Partially Hydrogenated and Trans Fats should be avoided at all times.
Cholesterol is not a FAT it is a lipid (fats are a subset of lipids) but it is important to keep an eye on serum cholesterol levels, particularly the ratio between high-density lipoproteins (HDL) and low-density lipoproteins (LDL). Dietary cholesterol plays an important role in many physiological functions such a cell membrane integrity, digestive function and synapse function amongst others. Organic, free-range eggs and grass-fed beef are both excellent sources of cholesterol. Research in 2007 by Reichman et al. showed a correlation between dietary cholesterol and skeletal muscle mass in 49 men aged 60-69. The research suggested cholesterol intake contributed to increased muscle mass following a resistance training program.
At SSC Nutrition Consultations can include Bioimpedance Analysis in order to determine skeletal muscle mass, fat mass, girth measurements and visceral fat measurements, Resting Metabolic Tests that can accurately measure an individual’s substrate use, i.e. fat burner or carb burner and Food Diary Analysis which can highlight trends e.g. calorie intake weighted towards the weekend, protein intake lacking in the morning, etc.
Keeping a food diary over a 7 day period can be a real wake-up call. You can download a food diary template from http://sportscienceconsultants.com/resources or simply write your intake down on paper. At the end of the week certain issues may be highlighted.
- Look at breakfast. Do you have a plan? Are you prepared or are you playing catch up from your first meal. My preference is to make 2 Nutri Bullet smoothies the night before.
Smoothie 1: Oats, Strawberries, Raspberries, Banana, Peanut Butter, Bio Yogurt.
Smoothie 2: Apple, Pear, Spinach, Cucumber, Ginger, Walnuts.
- What is for lunch? Can you take a prepped meal such as a Salad Nicoise to work? Are you training during lunch hour and if so do you have a healthy CHO & Protein snack to eat asap after training?
- What is your alcohol intake? Guidelines have changed recently. Are you getting enough alcohol free days? Remember it is very difficult to add skeletal muscle mass whilst your body is being exposed to steady intake of alcohol.
- What trends can you spot? One of my clients used to find Thursdays very difficult due to her daughters pre-school cello practice. It seemed to take her by surprise every Thursday waylaying her diet for the rest of the day. By keeping a food diary this was highlighted and she could plan appropriately.
Lastly, don’t worry too much about Body Mass Index (BMI) or Waist to Hip Ratio (WHR) just measure your abdominal girth with a line through the umbilicus. This is the simplest way to monitor changes in visceral fat deposition and AB girth also correlates highly with cardiac health.
TAKE HOME POINTS
- Your nutritional program should reflect your training program phase. A high volume, low intensity phase requires a higher energy intake whilst a muscle hypertrophy phase requires a higher protein intake compared to other phases.
- Ingesting too much CHO per hour can result in GI distress and negatively affect performance.
- Use multiple transportable CHO drinks for long events +2.5 hours.
- Protein + CHO post workout enhances muscle recovery and improves subsequent performance.
- Ensure adequate intake of DHA/Omega 3 fatty acids.
- If you are having problems reducing fat mass book a Resting Metabolic Test and a Bioimepedance Test in order to determine your substrate use and your daily energy requirement.
Richard Brennan is managing director of Sport Science Consultants Ltd. He is a clinically trained Exercise Physiologist with a BSc. in Sport Science and an MSc. in Sport & Exercise Physiology. Click here to read his biography.