VO2max

The monthly newsletter of RunCoachJason.com

Jason Karp, professional coach, consultant, freelance writer

April, 2005

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In this issue:

Integrating Science with Application—Running Economy

VO2max—An Aerobic Parameter with an Anaerobic Component 

Carbs

Writing

Research

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Integrating Science with Application—Running Economy

Want to improve your running economy?  One of the keys to becoming a more economical runner (i.e., to use less oxygen to run at a specific pace) is to enhance the steps involved in muscle fiber recruitment and contraction, improving the speed at which muscles produce force.  A number of recent studies have shown that power training with plyometric exercises or weights improves running economy, possibly by a neuromuscular mechanism. 

 

In a study from the Australian Institute of Sport presented at the American College of Sports Medicine conference in 2004, a group of highly-trained runners who added 9 weeks of plyometrics to their running training improved running economy and leg power more than did a group that only ran.  In another study from Finland published in Journal of Applied Physiology, one group of runners combined endurance training with plyometric exercises (5-10 reps of 20- to 100-meter sprints and jumping exercises) and lower body weight training with light weights (0-40% 1-rep max) lifted quickly, while another group did only endurance training.  Only the runners who did both the plyometric and endurance training improved their economy and 5-K time.  Two other studies published in Scandinavian Journal of Medicine and Science in Sports and Medicine and Science in Sports and Exercise, in which subjects performed 3-4 sets of 5-6 reps with heavy loads (85-100% 1-rep max) and fast speeds, also found improvements in economy. 

 

The common factor between all of these studies is the focus on speed.  The key in distance running, as in most sports, is to produce and apply muscle force as quickly as possible.  Both plyometrics and explosive weight training can help.  For more information, be sure to check out the October, 2005 issue of Running Times, in which I give specific recommendations for including plyometrics and explosive weight training in your training program.

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VO2max—An Aerobic Parameter with an Anaerobic Component

Although VO2max refers to the maximal amount of oxygen consumed per minute, and is therefore considered an aerobic variable, the speed at which VO2max occurs involves a considerable contribution from anaerobic metabolism, as it occurs at a speed faster than your lactate threshold.  This point seems to be lost on many runners and coaches, as this tells us something about the relationship between aerobic and anaerobic metabolism.  Although counterintuitive, the fastest rate of oxygen use occurs when there is also a lot of energy being produced without oxygen.  As discussed in March’s newsletter, the best way to improve VO2max is to run long intervals lasting 2-5 minutes at about 3,000-meter race pace, a workout that also includes a considerable anaerobic contribution.  Races for which a high VO2max is considered important (800 to 5,000 meters) have a high anaerobic contribution as well.  The biochemistry behind this matter is complex: when the Krebs cycle and electron transport chain are working at their fastest rates, glycolysis is also working.  In other words, the fastest aerobic motor occurs when an anaerobic motor is

also running.

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Carbs

The many proponents of low-carb diets like Atkins and South Beach would have the public believe that carbohydrate is some kind of poison.  Carbohydrate is the reason for our country’s obesity epidemic, the books say.  What an irony it is, then, that carbohydrate is the major source of energy for all organisms.  When we run, our bodies use blood glucose and muscle and liver glycogen as fuels.  At slower running speeds, some of carbohydrate’s metabolic responsibility for energy production is relieved by fat.  Although humans’ store of fat is virtually unlimited, with enough to fuel about 1,000 miles of walking, our store of carbohydrate is not, with enough to provide energy for only about 100 minutes.  Even with the contribution of fat oxidation helping to delay the depletion of glycogen, moderate-intensity running (70-75% VO2max) can only be sustained for 2-3 hours.  What the low-carb diets seem to ignore is that exercise is largely a carbohydrate activity. 

 

It has been known since the late 1960s that the ability to perform endurance exercise is strongly influenced by the amount of glycogen stored in skeletal muscles, with muscle glycogen depletion becoming the decisive factor limiting prolonged exercise at 65-75% VO2max.  Many studies have also shown that higher muscle glycogen availability results in a greater use of glycogen during exercise.  That muscles prefer carbohydrate as a fuel is so fundamental to exercise metabolism, even research examining supplementation with carbohydrate during exercise has shown that fatigue can be delayed.  With the well-documented decrease in muscle glycogen content that accompanies endurance exercise, an empty-refill cycle becomes evident.  When muscle glycogen is depleted by training, muscles respond to the empty tank by synthesizing and storing more than what was previously present.  Empty a full glass, and you get a refilled larger glass in its place.  (Muscles have a lot in common with college fraternity parties.)  All else being equal, long distance running performance can be considered as a proxy to muscle glycogen

content.  So after your runs, keep drinking carbohydrate-rich chocolate milk!

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Writing

Do you or someone at your company need someone to write copy for advertisements, catalogs, websites, brochures, or other literature?

Do you need someone to proofread and edit your writing before it is sent to a publisher?

Are you a student needing help writing your class papers, thesis, or dissertation?

Are you a student or professional who wants to make your résumé stand out and catch the eye of employers?

For more information, or to hire Coach Jason as a writer, e-mail

jason@runcoachjason.com.  

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Research

Scientific journals are not the best bedtime reading.  But every once in a while, something interesting can be found in them.  Here’s a sample...

 

A study published in the August, 2004 issue of Journal of Strength and Conditioning Research found that distance runners given caffeine before a run decreased their volume and rate of breathing while running and perceived the run to feel easier.  Many other studies have found that ingestion of a large dose of caffeine has a beneficial effect on distance running performance. 

 

A study published in the March, 2005 issue of Journal of Biomechanics found that the forces of impact and braking were greater during downhill running and less during uphill running compared to running on a flat surface, suggesting that running downhill increases the chances of overuse injury.  (But runners already knew that!)

 

Interest in the cardiovascular adaptations to endurance training have been of interest to scientists and health professionals since at least the time of the documented enlarged heart of distance runner Clarence DeMar, who won the Boston Marathon 7 times between 1911 and 1930.  A study published in the February, 2005 issue of Journal of Applied Physiology found that cardiovascular performance can be improved in untrained men after only 6 days of endurance exercise at 65% VO2max for 2 hours a day.  The subjects increased their blood volume, the amount of blood entering the left ventricle before contraction, and cardiac output, while their heart rate during exercise decreased.

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©2005 Jason Karp.  All rights reserved.