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Happy Friday! I went to 6am spin this morning, and it was a super sweat fest!  I usually don’t have time to shower afterwards, so hopefully I won’t be too smelly 🙂

Let’s take a look at fat-loading for this Fuel Your Fitness topic . . .  

While most that engage in endurance-type activities have known time and time again that carbohydrates are the body’s preferred energy source for performance, there have been some questions regarding fat-loading.  Fat is a substantial energy source, and if the body can adapt to utilize this source efficiently, it has been questioned if glycogen stores can be spared and endurance capacity increased.

The amount of energy stored as fat is in the range of 100-130,000 kcals where as total glycogen stores only total to about 2,000 kcals!

Carbohydrate is still a great energy source that is quick and efficient, although used up pretty darn quickly.  If there is not a substantial amount stored in the muscle and a little in the liver, when the blood glucose supply dwindles down in the latter stages of events without adequate fueling, your s*!t out of luck and hit the wall or bonk.

Fat oxidation is predominant in low to moderate intensity activities, but as the intensity increases carbohydrate becomes the preferred energy source and lipolysis decreases.  ATP (adenosine triphosphate) is the body’s main energy source for activity.  Only so much is made at one time and the body has to continually replenish.  More ATP can be made from carbohydrate than from fat, especially at high intensities when ATP breakdown is too fast to be match by the formation by fatty acids.

Endurance training actually also increases one’s capacity to utilize and store fat intramuscularly for energy, so one would think that fat loading could be a way to increase endurance performance, but the research hasn’t shown beneficial results . . .

• Overall while increasing one’s fat content in the diet has shown to increase fat oxidation in both short and long term loading regimens, there hasn’t been significant results seen in athletic performance in many studies.
• Even fat adaptation in ultra-endurance events (~65% VO2 Max, lasting longer than 4 hours) failed to show a statistically significant performance benefit (Carey AL, 2001).

Other things to consider . . .

• A high fat diet (60-70% of calories) can be difficult to maintain and can also present some cardiovascular health issues depending on the type of fat consumed.  On another note about fat, there is actually some confuting evidence against this.  Emily has some great posts on the Big Fat Question, and even shows that saturated fat may not be the only picture in heart disease.
• Increased RPEs (ratings of perceived exertion), along with lethargy and irritability, can be a side effect and of course is not good for performance or friends 🙂
• Intense training without adequate carbohydrate also poses the risk of immune suppression and illness. Carbohydrate consumed during intense activity helps decrease stress hormones like cortisol and limits some of the exercise-induced immune suppression (Nieman, DC., 2007).
• One study (Havemann L, 2006) found fat adaptation/carbohydrate restoration had no effect on overall time trial performance but compromised the ability of well-trained cyclists to perform 1 km sprints during the time trial. Even during longer, moderate-type activities, athletes need that edge and intensity to power through hills or sprint to the finish, and carbohydrates are what supply that energy.

Fat is still an important component in anyone’s diet, including athletes, and I believe it’s always good to go for balance and make sure to get 20-35% of calories from a variety of healthy sources of fat in the diet.

Overall, even though increasing fat adaptation may seem promising and it sure would make sense to be, it doesn’t equal performance benefits and is especially not beneficial for endurance athletes.

Any other thoughts?

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This weekend looks like it will be pretty packed already!  Tonight we are attending an Art Exhibition and Benefit where our friend’s art work will be featured for the first time.  Saturday I hope to get errands and random stuff done, and then it’s the SwankyRD‘s BIRTHDAY PARTY!!!  We’re going cosmic bowling baby!  And Sunday I hope to get a  50 miler in and hope I don’t keel over!

How has your activity shaped up this week? Many of you are pretty good at ‘just goin’ for it’ when it comes to fitness and also know when it’s a good time to take a rest, which is awesome!  It’s also important to understand that we ALL have down fitness days/weeks which is okay, and it’s never too late to jump back on the wagon to health.

• Sunday — Body Pump weight sesh
• Monday — Rest
• Tuesday — Rode to work 32 miles
• Wednesday — Rest
• Thursday — Abs, well I was going to go to body pump, but wanted to join some of Chris’ work friends as a farewell dinner for one of his co-workers, but it turned out to be a ‘boys only’ event and I didn’t go to the gym so I could make it : / Thanks a lot!
• Friday — Early morning spin
• Saturday — Rest
• Sunday — 50 miler!  go for it!

As far as my training goes, I can tell a noticeable difference in strength and the definition of my quads!  This is completely a new thing for me, especially being a dancer, but I enjoy it and it’s something exciting to strive for 🙂  I’d like to post a before and after picture, but I’m already 6 weeks into training and Chris is really weird about the whole thing, which is understandable.  I am still in the ‘increasing strength’ stage, but now I need to increase my mileage to easily tackle longer rides.  About 9 1/2 weeks to go, ahhh!!!

Happy Active Weekend! Any plans?