Kiwi Girl Health is your free online health resource! We are here to share knowledge in the areas of health and wellness so that you can live a healthier and happier life!

Our focus for the month of June is food for fitness!  Visit this site to pick up new pieces of information that will help you build a stronger, leaner, healthier body with the help of food.

 

 

Exercise and Carbohydrate Timing

 

 

Carbohydrates are the premium fuel for our muscles.  In fact, of the 3 fuels (fat, protein, and carbohydrate) carbohydrates are by far the most efficient when it comes to the provision of energy for the body.  However, when it comes to their contribution to optimal athletic performance and peak fitness it is vital to consider the time at which they are consumed.  If timing is off, carbohydrate intake can lead to weight gain and reduced physical performance.  If timing is well planned, carbohydrates can be one of our body’s greatest assets!

 

When carbohydrates are consumed they are broken down to glucose, causing an increase in the sugar levels of our blood.  In response to this elevation our body releases the hormone insulin, which goes to work to ‘clear’ this glucose.  The uptake of this glucose occurs first in the muscle cells of our body, where the glucose is converted and stored as glycogen.  Unfortunately, we do not have the ability to store unlimited amounts of glycogen and any excess glucose gets taken up by the liver and converted to fat!

 

When we exercise, the glycogen from our muscles is released so that glucose can be oxidized and broken apart piece by piece, resulting in the production of ATP - a prime source of energy for the body!

 

One major issue related to the consumption of carbohydrate for exercise is the body’s inability to store large amounts.   There is no such thing as unlimited glycogen storing.  Subsequently, during long bouts of exercise the body can be forced to tap into reserves of body fat and protein in order to generate the necessary energy to continue exercising.  This is where it is important to understand the effect of carbohydrate timing on exercise performance and/or the attainment of exercise fitness goals. 

 

If the goal is top athletic performance, the consumption of carbohydrates before and during the workout is of great benefit.  In effect, this can spare some of the glycogen that your body would have been forced to tap in to and you can perform at higher intensities for a longer period.  For someone aiming to exercise at a high intensity for a longer duration this becomes an important factor to take in to consideration. The harder you exercise, the more carbohydrate used, and intense exercise can result in up to 3 times as much glycogen use as mild exercise   The rate of fat metabolism is slow compared to the rate of carbohydrate metabolism and during intense exercise (when the body demands the fast delivery of energy) fat metabolism cannot provide energy quickly enough and the body must slow down. 

 

Longer, slower bouts of exercise, where intensity is mild and performance requirements are not as profound, can draw on fat as an energy source without the performance detriment.  As mentioned before, the use of fat is beneficial because it helps to spare some of the glycogen stores, supporting a successful endurance training session.

 

So, how can this information be applied to pre-exercise nutrition?

           

1)     If you are taking part in intense exercise, consider eating a light carbohydrate meal at least 1.5 hours (preferably 2) before your workout.  If you eat too soon before your workout, insulin will still be working to clear the blood of glucose and you will actually have a harder time mobilizing stored fuel.  Lethargy could be the end result – when you are looking for the opposite!  Also, if you eat too close to exercise the blood supply will be drawn away from your stomach to your working muscles, and you may experience extreme indigestion.

 

Complex carbohydrates, that are low glycemic are what you need as they provide a steady stream of energy to the body, and take a longer time to break down.  What is great about low glycemic foods is the fact that they will prevent any premature lowering of blood glucose levels before training, which can lead to fatigue. Complex carbohydrates can take 2 hours to break down, so by the time you are ready to exercise the fuel will be available for use by the body. Some good choices include:

 

§         oatmeal (plain, non-flavoured)

§         quinoa

§         brown rice

§         spelt pasta (remember, al-dente pasta is best because the firmer the noodle the longer the digestion time)

§         sweet potato

 

It is our recommendation that you attempt to purchase organic varieties of food, for more details on the benefits of eating organic, watch our for our article next month!

 

If your timing is off and you need to eat much closer to your workout, then you might consider eating a piece of fruit that has a medium GI, such as:

 

            Kiwi Fruit

            Oranges

            Mango

            Raisins and Sultanas

Or, conversely, consume a fresh fruit drink such as orange or apple juice, diluted in water. 

 

2)     If your goal is to specifically burn fat, pre-exercise carbohydrate intake is not as necessary, but remember that fat is not an efficient form of energy supply and your workout will not be super-charged.

 

PLUS!!  Though less-strenuous exercise promotes fat oxidation during the workout, more intense exercise leaves you with a larger EPOC (Excess Post-exercise Oxygen Consumption).  This represents oxygen consumption above resting level, oxygen that the body is utilizing to return itself to its pre-exercise state.  Put simply, your metabolism is elevated for a longer period following exercise!  Your body is working hard to get itself back to its normal state, and this work requires calories for energy.  As such, intense exercise can be a great way to encourage an increase in total caloric expenditure and therefore weight loss.

 

3)     Supplementation during exercise can be beneficial to supply ready energy and maintain hydration.  Unfortunately, even if you’ve eaten a good pre-workout carbohydrate meal, muscle glycogen depletion can and will still occur. If you consume a drink that is part carbohydrate (and part protein) you will delay the onset of fatigue due to lack of available glucose. 

 

4)      It is important to remember that the inclusion of protein before and during exercise is critical to the enhancement of performance and recovery.  To find out more about when and how to include protein click here

 

Carbohydrate and post-exercise nutrition

 

After exercise, the body is affected in a number of ways.  Glycogen is depleted, stored ATP and other substrates are exhausted, muscles have been damaged, and the level of blood cortisol has risen causing the body to break down tissue as opposed to build it up.  Such an internal environment will discourage tissue growth and prevent positive adaptations to exercise training.  Not what we want!!

 

Fortunately, the body is designed to respond to these changes by providing a short post exercise period in which all these negative effects can be avoided.  This is, however, only possible when proper nutrition is provided. 

Muscle glycogen re-synthesis rates are dramatically elevated during the immediate post-exercise period, as is the rate of protein synthesis.  As such, carbohydrate should be consumed during the immediate post-exercise period. Similar to re-stocking empty shelves in a grocery store, our body will re-stock our muscles cells with a healthy stack of glycogen.  Recovery is enhanced, and depleted energy stores are no longer so!

What is also great about consuming carbohydrate during the post-exercise period is that even in the face of high carbohydrate intake fat loss is still enhanced.  Confused?  After exercise the body is working hard to repair muscle damage and replenish energy stores and of course carbohydrate and protein are recruited for these important tasks.  What does this do?  It leaves fat as a prime source of energy supply during this period.  Glucose will be stored as glycogen in our muscles, fat will be oxidized to provide energy, muscle building will be accelerated, and so will fat burning!  What a great situation!  This exemplifies just how important it is to consume the right nutrients in the immediate period following exercise.

Since the post exercise period is the optimal time to replenish and repair damaged muscles, this is the time to consume easily digestible liquid carbohydrates and protein.  Why liquid?  This is simply because liquid and gel sources of carbohydrate are absorbed through the intestine and into the bloodstream faster than solid foods, and this way you can make sure that you are offering your body the energy it needs at the pace it demands them.  As opposed to during the day, you actually want your insulin levels to rise so that proteins, carbohydrates, and other nutrients can be shuttled quickly into the starving muscles. So at this point you can indulge in those higher GI foods!  They are actually recommended at this point because of the spike in insulin they cause.

Though everyone’s needs are slightly different (depending on intensity of the workout, weight of the person, and type of workout performed), a good general rule (for someone looking to increase lean muscle) for an immediate post-exercise drink is 0.8g of carbohydrate and 0.4g of protein for every 1 kg of your body weight.  This should be dissolved in 1L of water.  Please keep in mind that you want minimal fat and fibre in the immediate post-exercise drink because both slow the rate of digestion and absorption.  Simple sugars are the way to go, because they are absorbed the quickest.

For a home-made post-exercise drink, ideas for carbohydrate and protein combinations include:

 

Diluted Fruit Juice (Apple, Orange, Cranberry, Mango..try to use natural varieties with no preservatives or coloring added)

+

Hemp Protein Powder/Organic Soy Protein Powder

(if you would like to find out about the downside of using whey protein powder, please click here)

+

1L Water

 

30 minutes to 1 hour later it is a good idea to consume something more substantial. 

 

Shakes are perfect, as you can combine various ingredients to create a nutritious and well-structured drink.  An example of a great post-exercise shake that will nourish your need for carbohydrate (as well as protein) is shown below:

 

1 x banana (fast acting sugar)

1 x large scoop hemp protein powder  (for more information on the benefits of hemp visit www.fitsquad.ca)

1 x spoonful on raw organic honey (fast acting, simple sugar)

1 x tbsp Flax Oil

3 x cups of filtered water (if you prefer a creamier drink, substitute 1 cup of water with 1 cup of soy milk)

1 x tsp cinnamon

1 x handful of ice

1 x tsp almond butter

 

Do not forget that you should purposely use mainly high glycemic carbohydrates after you train.  Recall, you want the insulin levels to rise causing protein, carbohydrate, and other nutrients to be delivered quickly into the starving muscles.

 

Let us not forget PROTEIN

 

Those we have been focusing on carbohydrate, it is always important to include protein in the equation.  We will be visiting the addition of protein to your diet in the next few weeks!  Watch here for more information.