VO2max

The monthly newsletter of RunCoachJason.com

Jason Karp, running & fitness coach, consultant, freelance writer

February, 2007

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In this issue:

VO2max Distance Running Clinic Packet

Resting Metabolic Rate

How Do You Get Stronger?

Detraining and Fitness

In Press

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VO2max Distance Running Clinic Packet

Did you miss Coach Jason’s recent VO2max Distance Running Clinic, but still want to know how to become a better runner?  Don’t fret.  You can purchase the special clinic info packet, which includes the presentation handouts, for only $9.95.  You’ll find tons of information on the secrets of distance running, lactate threshold, periodization, hydration, and more!  And don’t forget you can always purchase my popular customized 5K, 10K, half-marathon, and marathon training programs for beginner, intermediate, and advanced levels.  Just e-mail jason@runcoachjason.com. 

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Resting Metabolic Rate

(excerpted from Karp, J.R. The Resting Metabolic Rate Debate.  Fitness Management. Jan. 2007.)

 

Among fitness professionals, the often (over)-used argument is that strength training will add muscle, which will increase people’s metabolic rates and, over time, will help them lose weight because muscles are “fat-burning machines.”  However, research has shown that each pound of fat-free weight burns about 8 to 15 calories per day, a negligible amount when you consider the 3,500-calorie deficit it takes to lose just one pound, and much lower than what is often publicized in the fitness community.  Therefore, if a 200-pound person gains two pounds of muscle, he or she will burn an extra 16 to 30 calories per day, taking 117 to 219 days to burn one pound’s worth of calories.  But since it takes a 3,500-calorie deficit compared to the number of calories consumed to lose one pound, not just a 3,500-calorie expenditure, it will actually take much longer to lose one pound from adding two pounds of muscle mass. 

 

If you’ve ever measured people’s resting metabolic rates in a laboratory, as I have, you’ll discover that it doesn’t differ much between people, including between those who are fat and lean, averaging about 200 to 250 milliliters of oxygen per minute, or about 3.5 milliliters of oxygen per kilogram of body mass per minute.  This equates to about 9 to 11 calories per pound of body mass per day.  As people lose weight (when caloric expenditure is greater than caloric intake, also referred to as negative energy balance), research has shown that resting metabolic rate decreases despite the maintenance of muscle mass from weight training.  Since no research has shown that resting metabolic rate is maintained much less increased when people are in negative energy balance, how can fitness professionals suggest that weight training increases resting metabolic rate resulting in weight loss? 

 

While a few studies have shown that resting metabolic rate (or total daily caloric expenditure) increases in response to either an aerobic or weight training program, many more studies have shown that it does not.  It has also been shown that resting metabolic rate is not significantly different between people of different aerobic fitness levels and is independent of training status.  Studies reporting an increase in resting metabolic rate have often been conducted on older adults who are more likely to show increases in resting metabolic rate due to the attenuating effect of weight training on age-associated losses in muscle mass.  Additionally, resting metabolic rate can be increased partially as a result of increasing caloric intake that often accompanies the increase in caloric expenditure with exercise (in other words, you typically eat more when you exercise more).

 

So what’s the bottom line?  Exercise is not likely to change your resting metabolic rate much, unless you’re older and have lost a significant amount of muscle mass over the years.  If adding some muscle mass by weight training does increase resting metabolic rate, it does so only slightly, not by enough to significantly impact weight loss.  You lose weight by expending more calories than you consume, not by trying to change your metabolism at rest. 

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How Do You Get Stronger?

If you’re weight training to change the way you look or get stronger, you’ll have to wait a while.  When you first begin lifting weights, ever wonder why you don’t get bigger muscles right away?  Although you begin to get stronger almost immediately after your first weight training session, the initial acquisition of strength (about the first 8 to 12 weeks) is largely due to neural factors rather than to an increase in muscle size (hypertrophy).  For muscles to contract and produce force, your central nervous system must communicate with your muscles.  In response to strength training, this communication is greatly improved.  For example, there is a greater amount of the neurotransmitter acetylcholine released at the end of the neuron where it meets the muscle, the ensuing action potential travels faster through the muscle, more calcium ions are released and interact with the contractile proteins, and your muscle fibers are stimulated to contract more frequently.  The result is a greater muscle force production even though the muscle’s size has not yet increased.  However, the most lasting and substantial improvements in strength require hypertrophy, so you need to keep training for long periods of time to get the most out of it.

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Detraining and Fitness

Have you ever gone on vacation and worried about losing your fitness? When you stop training, you can expect to lose some fitness because you’ve removed the stimulus for adaptation.  However, small reductions in training for a short time (about one week) won’t hurt your overall fitness and may even help, since it gives your muscles a chance to recuperate from all the hard work.  That’s why most competitive athletes taper their training before important competitions.  When you stop training, the loss of aerobic endurance is greater than the loss of strength and power, so if you’re pressed for time while you’re away from the gym, it’s better to go for a run than to lift weights.  Your muscles’ ability to use oxygen decreases after two weeks of inactivity, initially due to a decrease in blood volume (which decreases cardiac output) and subsequently due to decreases in mitochondrial aerobic enzyme activity.  However, the activity of the enzymes involved in the oxygen independent (anaerobic) pathways doesn’t decrease as much or as quickly, so you can maintain your strength for a longer time. 

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In Press...

Training Characteristics of U.S. Olympic Marathon Trials Qualifiers, my research article documenting how the best marathoners in the U.S train, with comparisons made between men and women and elite and national-class runners, appears in the Winter, 2007 issue of Track Coach, the official technical publication of USA Track & Field.

 

On Science and Running, my essay on how my unlikely status as a scientist has shaped my identity as a coach, appears in the January/February, 2007 issue of Marathon & Beyond.

 

The Top 3 Marathon Workouts, my article that describes the three most important workouts to prepare for a marathon, appears in the January/February, 2007 issue of Marathon & Beyond.

 

Shapely Shoulders, Part 2 of my Better Body series that describes how to get the broad or sexy shoulders you’ve always dreamed of, along with a shoulder training program, appears in the February, 2007 issue of Ultra-Fit magazine.

 

“I Can’t Catch My Breath”: Lungs and Running Performance, my article that defuses the myth that the lungs limit running ability, appears in the Winter, 2007 issue of Duke City Fit.

           

Get a Grip, my research-based article that discusses changes in body position and grip that changes the muscular emphasis of a variety of exercises, appears in the February, 2007 issue of Oxygen magazine.

 

My Fitness News contributions on weight machines and free weights, menstrual cycle and strength, hill running, and exercise and blood pressure appear in the February, 2007 issue of Oxygen magazine.

 

Also look for my contributions to the chapter, “Some Training Methods for Middle and Long Distance Running” in the new fifth edition of Track & Field Omnibook published by Track & Field News Press.

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To view past newsletters, go to http://www.runcoachjason.com/newsletter.

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©2007 Jason Karp.  All rights reserved.