Newsletter Archives

Lactate Threshold

CrossFit Atlanta Newsletter
News & Fitness Information from CrossFit Atlanta
February 26, 2007 - Vol 1, Issue 4

Lactic Acid is a metabolic by-product of the anaerobic metabolism of glucose or glycogen in the production of muscle force. As exercise intensity increases the rate of anaerobic energy production increases and the thus the rate of lactic acid production increases. It is the build up of lactic acid in the muscle that causes "the burn" feeling that makes you want to stop and go home to mama.

Athletes and coaches have long known that high intensity interval training improves the ability to operate at high intensities. For decades exercise physiology scientists have theorized about why this happens. They postulate that proper training improves lactate tolerance in several ways, which include: (1) training causes increased numbers of mitochondria in the muscle which allows aerobic energy procduction at higher intensities, and therefore reduces production of lactic acid, and (2) improved blood flow to and from the muscle lead to increased ability to "clear" the lactic acid away from the muscle. For a more scientific discussion, see Lactate Threshold by Stephen Seiler. The "Lactate Theshold" is the intensity level at which blood lactate starts to rise significantly, and the objective of many endurance athletes is to raise their lactate threshold.

Startling new research by George Brooks at UC Berkeley indicates that higher lactate thresholds are seen in properly trained athletes because the trained muscle can actually use lactic acid as a fuel. Brooks

This research simply confirms what elite coaches and athletes have known for ages: that hard and fast interval training improves improves your ability to go hard and fast, recover quickly and then go hard and fast again. At CrossFit, "we bathe in lactic acid," not because the scientists tell us to do so, but because it produces incredible fitness results.

Intermittent Fasting

CrossFit Atlanta Newsletter
News & Fitness Information from CrossFit Atlanta
February 21, 2007 - Vol 1, Issue 3

Intermittent Fasting
There's alot of exciting research and experimentation going on with a new dietary approach called Intermittent Fasting.
35 years ago Dr. Atkins first got in hot water with the medical and nutrition establishment by popularizing the notion that humans as a species had not had time in evolutionary terms to adapt to the higher carbohydrate, grain based diet that came on the scene about 10,000 years ago with the devopment of agriculture. He committed dietary heresy by advocating a lower carb, higher fat diet than the one recommended by the U.S. Dept. of Agriculture. Currently all of the many variations of low carb diet proceed from a similar theoretical foundation in evolutionary biology.
The Paleolithic Diet takes the evolutionary premise to it's logical conclusions by eliminating items not in the diets of our hunter-gatherer ancestors, namely grains, legumes, and dairy.
Intermittent fasting, "IF", goes even further and seeks to mimic not only the content of the caveman's diet, but also the erratic timing of meals in the brave old days before grocery stores. Some folks doing IF eat every other day. Others cram all their daily meals within a 4 to 6 hour window. Both methods are producing some interesting and very positive results in terms of weight control, insulin sensitivity, hormone profiles, lipid profiles, and many other biological health markers. You can read much more about it in one of our favorite publications, The Performance Menu. Issue 6 and Issue 17 have terrific articles on developments in this area. Issue 19 has an article on when Intermittent Fasting is contraindicated, which is medical lingo meaning "when not to do it."

The Myth of The Fat Burning Zone, part 2

CrossFit Atlanta Newsletter
News & Fitness Information from CrossFit Atlanta
February 11, 2007 - Vol 1, Issue 2

Do you know anyone who jogs for miles every week and cannot lose weight?

The Fat Burning Zone is supposed to be exercise done at around 50% VO2 max or at a heart rate of around 120 for a 30 year old. In other words, slow and easy, and jogging or other slow paced exercise on "cardio" machines is touted as the way to lose weight. Runners call this training "LSD": Long, Slow Distance.

Last week we discussed the math involved, that while training in the so called "Fat Burning Zone" does burn a higher percentage of fat for fuel than higher intensity exercise, it does not necessarily burn a higher total amount of fat. In fact, sitting on the couch watching TV burns a higher percentage of fat than any exercise.

But there's more to the story than just the amount of fat burned during the exercise session. High intensity exercise raises your metabolism for a more extended period of time post exercise than slower paced aerobics. That's one consideration, another is that high intensity exercise builds more muscle than low intensity. Muscle burns fat while at rest, yes, even while you sleep.

A good diet is essential to weight loss and health, but diet being equal, more vigorous workouts will give more fat loss than slow and easy workouts.

The Myth of The Fat Burning Zone, part 1

CrossFit Atlanta Newsletter
News & Fitness Information from CrossFit Atlanta
February 3, 2007 - Vol 1, Issue 1

We are often asked how short, intense workouts can provide the better fat loss benefits than traditional long duration, low power workouts in the so called "Fat Burning Zone." Tony Leyland of the University of Vancouver takes a stab at answering that question in the February 2007 CrossFit Journal in an article entitled, "The Myth of the Fat Burning Zone."

We've all seen the charts on cardio machines and on the walls of traditional gyms that purport to show that the most effective fat burning exercise occurs when the heart rate is in the range of 55% to 65% of maximum, in other words when we are execising at a mild to moderate intensity. Such charts bring Mark Twain's aphorism to mind, "There are three kinds of lies, 'Lies, damned lies, and statistics.' "

The chart and the myth are based on research which shows that when we exercise at 50% of VO2 max our body draws about 50% of its energy from stored fat, and that when we go to higher intensity, 70% of VO2 max, we only draw about 33% of our energy from stored fat. All this is true, but the chart and the myth are based on the false premise that higher percentages mean higher totals. The truth is that so much more energy is used in high intensity exercise that more total fat is burned. Put another way, a higher percentage of a small number can yield a lower total than a smaller percentage of a large number. A perhaps more understandable analogy is that 1% of Bill Gates' fortune is way more than 100% of most folk's weatlth.

There is more to this story. Stay tuned.