Showing posts with label Exercise Physiology. Show all posts
Showing posts with label Exercise Physiology. Show all posts

Wednesday, 13 August 2014

Nutritional Practices for Ultra-Endurance Events

Following on from last week’s blog about the demands of ultra endurance events, this week I will start to look at some of the nutritional practices that athletes can apply when training and competing in ultra-distance events.  

Appropriate and consistent training is one of the key factors in ensuring a successful performance in an ultra- distance event and supporting this training with the appropriate nutrition will also ensure that the athlete is ready to give their best performance on race day.

Preparation is also vital for race day success and  thorough planning and organisation when it comes to nutrition will ensure that a compromise is reached between achieving a light pack weight and carrying sufficient and effective fuel for the race.

Hydration

Staying hydrated and replacing fluid lost through sweat is important for not only performance but also for health reasons. Minor levels of dehydration will affect both physical and mental output whilst training and competing. Significant dehydration creates a significant risk of heat stroke and severe dehydration could lead to death.

During the week prior to the competition, the athlete should drink the recommended 2L per day and replace fluids lost through sweat in training to make sure that hydration levels are optimum levels before the start of the race.   

On race day, the athlete should start drinking as soon as they have woken up, and try to consume approximately 500ml before the start of the race.  This will ensure that any small fluid losses overnight are replaced.

During the race, the athlete should aim to replace the fluid lost through dehydration. This will be difficult, as most athletes cannot tolerate large fluid intake, especially in hot conditions.  A good compromise is to limit dehydration levels to less than 2% of the body weight. Measuring sweat rates during training and build-up races, as mentioned in an earlier blog, will help estimate how much they will need to drink.

Athletes should choose a drink which is palatable, not fizzy and, for these events, fluid which provides carbohydrate and electrolytes. This doesn't need to be a branded sports drink; in fact, a home made squash drink with a pinch of salt can be as effective and, for some, more tolerable than a sports drink. 

Carbohydrate

A lot of focus was previously been put on carbohydrate loading in preparing glycogen stores for the race. However, this will occur naturally providing that high carbohydrate intake is consumed alongside a pre-race taper and the focus which was previously suggested is not necessary.

Ultra endurance events often have early starts with minimal time on the morning of the race to get the appropriate nutrition on board. High Carbohydrate, low fat and low fibre foods should be on the list for athletes to eat and at least 100g of carbohydrate is a good amount to aim for to top up glycogen stores. Good examples include white bread jam sandwiches, cereal bars, breakfast cereals, bananas and fluids such as fruit juices, soft drinks and sports drinks. To facilitate rapid gastric emptying and nutritional absorption food should ideally be consumed 3-4 hours before race start.  Closer to the start of the race (1hr), a further carbohydrate snack will help prevent decreases in blood sugar levels during the early section of the race.

During the race, muscle and glycogen levels will normally last between 60-90 minutes, before the body needs to turn to other energy sources. At this point, the athlete is unlikely to maintain the same output and is sometimes known as hitting the wall. Maintaining carbohydrate levels during the competition will help the athlete to maintain output for longer.

The recommended intake is 1g of carbohydrate per kg of body weight per hour, and can be consumed in a variety of forms. For most athletes this will mean an intake of at least 50gms of carbohydrate every hour. Common sources include sports drinks, gels and bananas, but, during the latter stages of longer distance events, sandwiches and more savory snacks are common choices.  The following foods contain 30-60g of carbohydrate:
  • 500ml fruit juice or soft drink 
  • 500ml Sports Drink  
  • Sports or Energy Bar
  • 2 handful of sweets or dried fruit
  • 4-6 Jaffa Cakes
  • Cereal Bar
  • 2 Carbohydrate Gels
Food choices will often depend on the race provisions, athlete preferences and the ability to transport them during the event, all of which should be researched and practiced during training, and preferably a test race. Athletes must also have a 'plan b' just in case things don't go to plan on race day, or the athlete suffers stomach discomfort.

Tuesday, 22 July 2014

Training and competing in the Heat - what can you do to help?

As Britain enjoys one of the warmest summers I remember, I was asked the question, 'how does heat effect your training and what can you do to help your training and racing in the heat?'

One of the main effects of heat is an increase in perceived effort and the decreased motivation to go out and perform. Training or competing seem much harder and therefore times can suffer either in training or competition.

But what are the physiological effects of the heat?

The main ones are:
  • Dehydration
  • Increased Heart Rate
  • Reduced Blood Flow (and subsequently oxygen) to the working muscles.
Dehydration - I have already covered dehydration and why and what we should drink in a previous posts. But why does the risk of dehydration increase as the environmental temperature increases? 

Thermoregulation is the body's way of maintaining a consistent internal temperature, vital for bodily functions which keep us alive.  One of the ways that the body looses heat is via sweating, with the rate of evaporation linked to how well the body is cooled and the atmospheric humidity. When humidity is low evaporation increases, when humidity is high the rate of evaporation decreases and less cooling occurs.

Sweating leads to fluid loss, and dehydration occurs from the inadequate replacement of fluids. It is thought that every 2% loss of body weight through sweat can lead to about a 4-6% decrease in performance.  If this fluid is not replaced an athletes blood volume decreases, less blood returns to the heart and less oxygen rich blood reaches the muscles. You produce less energy aerobically and you run slower for a given effort level.  As it gets hotter, this effect is increased. The more heat that needs to be dissipated, the greater the proportion of blood diverted to the skin.

What can you do?

Training in itself provides some adaptation to the heat. It increases the total plasma volume which is why the fittest athletes (and likely those with the highest plasma volume) typically adapt more easily to the heat and perform better.

Regular training in the heat can result in it becoming easier to maintain a faster pace and reduce perceived exertion by increasing blood plasma volume, increasing sweat rate, reducing heart rate at a given pace and speeding up the onset of sweating. These adaptations make it easier to perform in the heat and can be noticed after only a week or two of heat exposure.  Training in the same temperatures as you would be competing at can have a massive positive affect.

Heat also effects intensity. Some athletes may benefit from moving training focus away from a certain time goals to running at an equivalent efforts. Sessions could be moved away from a track, to make it easier to pay attention to feel and perceived exertion rather than split times

What can you do for racing in the heat?
  • Adjust preparation - increase the layers in training to replicate warmer temperatures when you race. I have known triathletes preparing for Kona do bike sets next to a radiator with additional layers to prepare themselves for the heat they could expect when they race
  • Increase fluid and electrolyte intake in the days prior to racing to make sure you are hydrated
  • Stay as cool as possible before the race (sponges)
  • Perhaps have a shorter warm up
  • Pay more attention to perceived effort rather than race splits 
The other bit to recognise is the signs and symptoms of heat stroke:
  • Headache
  • Dizziness and light headedness
  • Lack of sweating despite exercising in the heat
  • Dry Skin
  • Muscle weakness or cramps
  • Nausea and Vomiting
If you do train in the heat and experience any of the above, try to get in a cool environment and drink plenty of water.

Tuesday, 4 March 2014

Lifestyle management at altitude

Altitude training is forming an important part of the training programmes of many endurance athletes.  Living at altitude can pose a range of challenges, however, and particular aspects of lifestyle may need additional attention, particularly in relation to preventing overtraining and boredom.

Athletes may become lethargic because of the boredom, and those who fail to embrace the local culture may regret missing out on potentially inspiring and enjoyable experiences.  It would be a shame to fly all the way to South Africa, and never to see and animal in the wild!

Conversely, those to try to fit too much in, fail to recover adequately from training.  Attempting to fill the time between training with some more training will lead to burnout.  You could get addicted to computer games (or sudoko, strib scrabble, or poker for training kit) and delay or skip training as a result.  Spending all day visiting sites and attractions, may result in sore feet, tight muscles and increased risk of injury.

If you fill all your spare time with sleep, and may generally lethargic, or become unable to sleep at night.  You will need more sleep than normal at altitude, and afternoon naps are not only acceptable, but generally recommended.  But oversleeping, or sleeping to kill time may be detrimental to your training.

Spending all your time sunbathing isn’t the answer either.  The sun’s UV rays are stronger at altitude, and you will be more susceptible to sunburn than at sea level. 

You could also dragged into other people’s routine.  Having other people around you is a good thing, but remember that everyone responds to altitude different, and you may need more recovery time than others.  Finally, spending too much time with your friends or training partners can lead you to getting on each other’s nerves.

Of course, these factors may be similar to the challenges that full-time athletes face in their everyday lives.  We will revisit the pros and cons of being a full-time athlete in a future post, but in essence, athletes become full-time athletes when they go away on training camp, and that can have positive and negative aspects. It isn’t all bad of course, but care must be taken to not slip into the many pit falls.

Don't miss out on the opportunities that training abroad can offer

The training camp mentality
Training camps can be a great way of injecting a new impetus into training.  A new environment can be energising and brief, intense spells of training can help athletes reach a new level.  Athletes tend to be more motivated when they are training in a group and have no other distractions.  Training camps are not without their pitfalls, however, and being over motivated can be particularly detrimental when it comes to training stints at altitude.

Taking time to acclimatise to altitude can be the key to a successful training camp.  Too often I hear people saying that they’ve done their hardest ever week of training or hit new ‘personal best’ mileage figures while training at altitude, or tweeted about how much running at altitude has ‘kicked their asses’.  

At sea level, training in a group can help stretch most athletes to achieve their best.  Occasionally trying to keep up with better athletes can sometimes reap results.  Training in a group at altitude, however, is generally a bad thing.  Every athlete respond to altitude differently, and in addition to risking your physical health by working too hard, competing and measuring yourself against others can have detrimental effects on your mental performance. 

Key advice
  • Work out your own programme with your coach and follow it
  • Monitor your HR, RPE and general wellbeing, and adapt your programme if required
  • Remember that less is more.  Just because you’re away on training camp, doesn’t mean that you have to train all the time.  Recovery is part of training too.
  • Don’t get dragged into the group mentality
  • Avoid going away with training partners that are overly competitive in training


Rest and recovery
We’ve all heard that resting is training too, but nowhere is the sentiment more true than when training at altitude.  Most of the physiological adaptations that occur at altitude, actually happen at rest.  Living at altitude is far more important than training at altitude (unless of course your training to compete at altitude). 

Basic acclimitisation to altitude takes approximately 14 days, though this varies depending on the individual.  During this time resting and training heart rates will be elevated, recovery times between intervals will be significantly increased, and more sleep will be required.  Your body will be working hard to increase EPO secretion, build new red blood cells, and to respond to the acute effects of the lower air pressure and oxygen availability.  Sometimes it’s best to just let the body get on with that.

Key advice
  • Reduce overall training volume by 10-20 percent during the first week, and increased gradually over the next three to four weeks.
  • Reduce the intensity of interval sessions by 5-10 percent initially, and increased gradually.  Intervals should be shorter than normal, and recovery time between them doubled. 
  • Take an additional recovery day between hard workout days.  Use resting HR as an indicator of recovery, and skip any planned workout if the HR is elevated more than normal.
  • Remember that there are huge individual variations in response to altitude.  Listen to your own body and don’t measure yourself against others.
  • Remember, with altitude training, less is more, particularly during the first two weeks. 
The Grand Canyon makes a great day out when training at altitude in Flagstaff

The boredom factor
Boredom can be an issue when training at altitude, and striking a balance between killing time, relaxing, and embracing the sites and culture of your training environment, can be difficult.  Boredom can lead to depression, so susceptible athletes should take particular care.

If you’re in charge of your own travel plans, choose somewhere that will cater for your entertainment needs.  If you don’t like sitting around all day talking and drinking tea, then Kenya may not be for you.  Choose a big city if you like to have lots to do; and smaller towns if you prefer to be close to nature.

Key advice
  • Decide on one or two things that you would really like to do while you’re away, and then decide where those activities will best fit into your training programme.  A safari might be a good way to recover from a long haul flight and adjust to altitude, while a trip to the grand canyon might be a suitable activity for a rest day. 
  • Have one worthwhile task to do while you’re away. Catching up with university work, doing an online course, writing blogs or magazine articles, or updating your website are just some of the projects that you could complete.
  • Enjoy your mealtimes; it’s not every day that you can take your time eating food.  Dining halls are also a good way to meet new people, and to soak in the culture of your surroundings. 
  • Not everyone loves to eat, sleep and breathe their sport.  Find what works for you and plan accordingly.
Chess or draughts can be a great way to pass the time and keep the brain active

Nutrition and staying healthy
Diet is very important when training at altitude, and adjustments may have to be made to ensure that you are getting all the nutrients that you need.  

Since more oxygen is required to break down fat than carbohydrates, 80 percent of calories should be derived from low glycaemic carbohydrates.  Meals should be taken every 4 hr.  Increased carbohydrate utilization may result in glycogen store depletion, so make a conscious effort to replace carbohydrates during and after training.

Reduced nutrient absorption in the gut at altitude results in greater faecal losses.  Maintaining a high proportion of carbohydrate, and ensuring that overall calorie intake is adequate may reduce or offset this faecal loss.  Basal metabolic rate increases for the first 4 days of altitude exposure, particularly in females.  After 4 days metabolic rate begins to return to normal, but remains above sea level values. 

Some individuals may experience reduced appetite.  Small but regular meals, and eating a variety of fresh products, may help.  Apples and grapes in particular have natural chemicals which increase appetite.

 Iron is also very important and depleted iron stores is one of the reasons why some people do not respond to altitude.  Iron is a mineral that is essential in the production of haemoglobin.  Haemoglobin is the part of the red blood cell which attaches to oxygen and transports it around the body.  As the body turns iron stores into additional red blood cells in response to the hypoxic conditions and subsequent increased erythropoietin syntheses, the demand of iron rises, and with it the risk of developing anaemia, even in health runners.

There is risk of immunosuppression, and a subsequent increased risk of upper respiratory tract infections and gastrointestinal infections, at altitude.  It is important that you listen to your body, have adequate vitamins (A, folic acid, B6, B12, C and E) and minerals (copper, selenium and zinc) in your diet, and replace carbohydrates quickly after exercise.

Because of increased ventilation, increased urinary water loss, and low humidity at altitude, the potential for dehydration is increased.  Caffeine-free fluid intake should be increased by as much as 4 litres per day.  Monitor morning urine colour to ensure that fluid needs are being met, and reduce caffeine consumption.

Dealing with Injury
If you are training at altitude, and get an injury that prevents you from carrying out your normal training, it is best not to panic.  Depending on the severity of your injury, how far you are into your trip, and on the duration of your planned trip, you have a number of options.

The most important thing is that you get treatment for your injury.  If you do not have support personnel with you, cannot find access to a suitable physiotherapist, and do not know what your injury is and how to treat it, you may be best taking complete rest.  If you have a long trip planned, you could look at shortening your trip.

Even if your ability to train is severely hindered by your injury, you will still benefit from sleeping at altitude.  If you would have to rest even if you were at home, you may still be able get some benefit from your trip, and the solitude of altitude may help with adherence to rehab exercises.

Cross-training may be particularly beneficial at altitude and cycling, aquajogging, or even just walking, may be sufficient to raise the heart rate to sea level easy exercise levels in some individuals.

If you are susceptible to injury, or have a recurring injury, ensure that you have access to physiotherapy, and/or medical backup, have access to cross-training facilities if required, and have investigated if the trails are suitable for you.

If all else fails, and if it’s not practical for you to go home early, consider that your injury may be your body telling you to take a break.  Consider if you actually need a holiday.  Make a conscious effort to make the most of the trip, and add in some extra sightseeing, make some new friends, and relax.  Make the most of the hypoxic air!

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My recently published book, Notes from higher grounds, is available through Amazon (click on image below).  It is essentially a travel guide for those looking to arrange a trip to altitude, and covers 15 different venues in detail, but also includes practical advice on how to deal with travel and training at altitude.