Understanding the Elements of Endurance Training

The Cardiovascular System – Of Pipes and Pumps

By Betsy and Bob Youngman

Note: A more extensive treatment of this subject is presented at our website Brave Enough. The essential points are reviewed here.

 

In the simplest terms, when we speak about training for an endurance sport like cross country skiing, there are two primary systems that will be the focus of training – the “pump” and the “pipes.” The pump is the heart, which delivers oxygen-containing blood to operating muscles via a system of pipes (aka the vascular system). Different types of training are utilized to stimulate the development of these primary systems and these “types” of training will form the basis for a training program.

Obviously, our lungs play a central role in making sure that the “pump” has the oxygen-containing blood available to pump. Generally speaking, for a healthy individual the supply of sufficient quantities of oxygen is not a limiting factor for endurance activities.

The cardiovascular system is best developed by repeated bouts of long-duration, low-intensity activity. Such training involves continuous, low-level stress that requires significant blood flow to operating muscles. The heart is quite pleomorphic and will respond fairly quickly to training stimuli that require increased blood flow. While this blood flow and muscular activity will grow muscle, our bodies also respond to the training stress by increasing the output of the heart and maximizing blood delivery to the muscles.

Increased blood delivery is facilitated by increases in capillary density in the tissue in and around these muscles. Additionally, under this same training stress, cell organelles, known as  mitochondria , grow and become more numerous in muscles. Mitochondira, using primarily fat and carbohydrate as fuel, produce a chemical called adenosine triphosphate ( ATP ). ATP is what enables muscle contraction via a complex set of biochemical reactions. The more numerous and bigger the mitochondria, the more fuel that can be processed and the more energy available for muscular activity.

Because of these very positive adaptations, such long-duration, low-intensity training is the focus for that part of our endurance training devoted to developing both our “pump” and our “pipes.” This type of training is the “base” aerobic development that we have reviewed earlier and is fundamental to all training for endurance sport.

Lactate Metabolic Processes

At the other end of the intensity spectrum, relatively short (1-15 minutes), high-intensity activity will have additional and substantial impact on the development of the heart and it’s ability to pump oxygenated blood out through our “pipes.” Increased cardiac output can be particularly large for those who do not have a history of endurance training or for those who are just returning to training from an extended period away. For those with a consistent long-term training history (think years), increases in cardiac output with such high-intensity training are significantly less dramatic since the upper limit to the potential output (aka VO2max) is considered to be significantly controlled by genetics – i.e. there is a “genetic ceiling” for VO2max that can be approached but not exceeded. As discussed previously, declining VO2max represents one of the “Big Three” limiters to performance for masters athletes. Therefore for the aging athlete, where a progression away from high-intensity training is common, high-intensity training is critical to full development of one’s potential.

Importantly, high-intensity training will also provide the necessary stimulus for improved metabolism of a product of cellular energy production called  lactate. You likely have heard of accumulating lactate as a “bad” thing for endurance performance. It isn’t; in fact lactate plays an essential role in the energy production cycle in humans. We will not go into the details of this here but it is covered in the extended post on this subject at our website Brave Enough.

Ways To Improve LT, VO2 Max, Economy and Strength

WAYS TO IMPROVE LACTATE THRESHOLD (LT)

* also called the “anaerobic threshold (AT)”

  • Large volume of training at endurance intensity (adaptation occurs over months and years)
  • Train around the LT: 1 – 3 workouts per week over 4 to 8 weeks (adaptation occurs over days and weeks)

 

WAYS TO IMPROVE VO2 MAX

  • Max V02 is built through a large volume of endurance intensity training!
  • High intensity intervals (at 95% of max); 1 – 3 workouts per week over a 4 to 8 week period (adaptation occurs over days and weeks)

 

WAYS TO IMPROVE ECONOMY

  • Improve Technique
  • Strength Training
  • Intervals and Speed
  • Equipment (less friction on the snow for instance)

 

WAYS TO IMPROVE STRENGTH

  • General
    General and maximum strength enables the athlete to build specific strength safely and to maximum effect. General strength covers all major muscle groups, targeting the body’s core and important joints.
  • Specific
    Specific and endurance strength is of primary importance to cross-country skiers. It uses ski specific motions, intensities and duration.

Determining Lactate Threshold

Threshold changes day-by-day and, with training, improves week-by-week and month-by-month. The only way to know, and “know” is a bad term to use because it is a changing value, is to take a lab test aimed at finding the threshold.

Athletes have to learn to feel the threshold as they cannot get tested everyday. The test, as well as using a portable lactate tester in training, serves to reinforce or confirm what they feel their threshold is, or what they feel their easy pace is, etc. Recreational skiers can get tests at university laboratories or sports centers for very reasonable prices.

If they aren’t interested in this, they will have to use a formula and/or go by feel.

It’s a comfortably hard pace that can be maintained for upwards of an hour and a half. Formulas are not accurate but may give you a start. A skier’s threshold is often between 80 and 90% of max (and even higher). Wear a monitor and, starting slowly, build up your pace gradually paying close attention to your breathing and heart rate. When your breathing is hard but rhythmic and in control and you feel taxed but as though you could go for a good long while then you are probably around threshold. When your breathing becomes a bit ragged and just out of control, and you feel that you could not go for very long then you have crossed over your threshold. Note your heart rate all along the way. The heart rate where you are running a bit ragged is above threshold, so error low. It can be the case that you have predicted your threshold at 175 one day but are running ragged at 173 another day.

What you hope is that you notice the running-ragged-heart rate creeping up. If it is going down, then you know you are training too hard, too much, and/or resting too little. It is a flexible value, so don’t think that this can all be boiled down to some numbers. You will have to be involved in deciding for yourself how fast to train regardless what the heart monitor tells you.

Don’t make it too complex. Easy feels easy, hard feels hard… tired feels tired. Trust what you feel, and train well.

Determinants of Performance

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Vo2 Max. Maximum oxygen uptake (Engine Size – how big is the engine?) This is the ability of the circulatory system to transport oxygen and of the muscular system to extract and use oxygen. Vo2 max is an excellent indicator of aerobic fitness, but a poor predictor of performance within a homogenous group of athletes.

Lactate Threshold. (RPM’s – how high can you race the engine?) Lactate threshold (LT) is the ability to continue using the aerobic system to replenish ATP at high speeds. It is expressed as power output at LT, velocity of LT or percentage of Vo2 max. LT is one of the best predictors of endurance performance.

Economy. (MPG – how many miles per gallon does your engine get?) Economy can be defined as the amount of oxygen that it takes for an individual athlete to go a given speed. More economical athletes will have a lower oxygen cost at a given pace relative to a less economical athlete. This can explain why an athlete with a lower VO2 max can still outperform an athlete with a higher VO2 max. Economy is one of the best predictors of endurance performance.

Strength. Strength is defined as the maximum force that can be produced in one all out effort. Muscular endurance is related to being able to maintain a submaximal force repeatedly.

Source: SkiPost


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Skier Self Analysis

Place a check in the box on the right that best agrees with the statement on the left.

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Checks moving from upper left to lower right indicate strength in Endurance and a weakness in speed. Checks moving from upper right to lower left indicate strength in speed and a weakness in endurance. Checks pushed right in the middle of the graph indicate a high-end fitness weakness, such as low VO2, lactate threshold and/or poor economy. Only testing at a qualified lab can determine where your physiological weakness in this zone lies.

You can gain some beneficial information from analyzing your performances in your five best and five worst races. See if you can find trends that might help indicate your strengths, weaknesses (area’s of greatest opportunity) with regard to fitness, strategy, diet and your race and pre-race habits. Things to consider are the race distance, technique, individual or mass start, snow and weather conditions (cold/warm, soft/hard tracks), course type (hilly, flat, steep, gradual), strategy (start hard/easy, attack the hills or ski an even tempo), nutrition (general, morning of, day before), other (travel, sleep, emotional state, race size.)

– SkiPost.com

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Summer Training – The Build Up

Cross-country skiing is a primarily aerobic sport. The best way to develop your aerobic system, and even your higher end fitness (V02 max and lactate threshold) is with easy to moderate (60 to 80% of max heart-rate) intensity distance (45min to 2hr) sessions. This type of training comprise about 80% of the training load, even for elite ski racers.

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This being true, it is also the case that the training week should be built around one to three harder training sessions. A harder training session is either a short hard session or a long easy session.

For instance many programs are built around two interval sessions and one long (3hr) easy (heart rate around 70% of max) session. Your body adapts to a certain stress after 4 to 6 weeks and so if you don’t change that stress, doing what you have already been doing will only serve to maintain what you have built.

It can be helpful to look toward your racing season and plan backward. You should end up with a plan that builds toward the racing season. The basic idea is to build your aerobic base over the summer, work on more race like aerobic and anaerobic fitness in the fall and early winter, and race fast in the winter.

In the summer then you would consider doing mostly easy to moderate intensity workouts with one session a week of harder training, and some strength training. As the summer/fall/early winter goes on you extend the duration of the workouts gradually, making sure you get lots of rest so that you are getting stronger and feeling better rather then getting more and more tired as the summer goes on.

There is a lot of training material out there, but this is the basic idea: training breaks the body down, rest builds it back to a level higher than before training. Remember REST builds the body up.

by SkiPost.com

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Can you give more detail on how to calculate training load?

A popular method is a 1-10 scale which coincidentally corresponds to general lactate levels. Another very simplistic method, which is what we are using in CXC Academy, is an intensity scale 1-5 that corresponds with the training levels 1-5.

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In short, a consistent unit of measure for time and intensity is necessary to measure load. We use hours to measure duration and a 1-5 training intensity scale to measure intensity for purposes of CXC Academy. Measuring load and not just duration alone is an excellent method to measure training and how much one can handle week to week, month to month and year to year.

For example, one workout might have 15 minutes of warm-up, 20 minutes of Level 4 intervals (5X4minutes) with 4 minutes recovery in between and then a 15 minute cool down. The total training load of that workout would have a load of:

Level 4 – 0.33 hrs X 4 = 1.33 TL.
Level 1 – 15min warm-up+4min*5 recovery time between intervals+15min cool down = 50min or 0.83hrs
0.83hrs X 1 = 0.83 TL

Total effort is 1.33TL + 0.83TL = 2.17TL

We often analyze total training load per training level per week. For example, 10TL for the week in Level 1 is 10hrs of Level 1 training for that week.

I hope all the math makes sense,

by Bryan Fish, CXC Academy Advisor / U.S. Ski Team Continental Cup Coach

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Correlate Training Intensity to Consistent Race Intensities

Screen Shot 2015-04-13 at 2.04.55 PMTo preface, it is important to note that everyone is different and any “correlation” have deviation. Some athletes have a narrow heart rate range (130-170bpm) while others have a very broad range (100-200bpm). Using a percentage scale on these two extreme situations makes it challenging for both the coach and the athlete. This is why we test blood lactate and/or VO2/CO2 kinematics. We are ample to achieve thresholds and estimated break points to set training zones. We encourage you to do the following in the mean time to set your training zones:

  • VO2 max training is approximately equivalent to a steady state max effort for a race lasting 12 minutes.
  • Determine your heart rate/ effort for a steady state for a 30minute event. This is a good level 4 pace for this time of the year and the really hard VO2 max efforts can be added in October or November to dial things up a notch.
  • Determine your heart rate/effort for a steady state 45-90min time trial. This effort is approximately equivalent to your lactate threshold or anaerobic threshold. This is your level 3 pace.
  • Finding MAX Heart Rate – This is painful, but do a couple L4 intervals to work up and then find a steep hill of about 60-90 seconds long and sprint up it as hard as you can. This will get your max HR. Personally, I don’t think finding one’s max HR is that important if you have a good understanding of HR at the 3 previous paces above.

Bryan Fish / CXC Academy Advisor, U.S. Ski Team Continental Cup Coach

 

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