As someone who’s never been particularly fast or had the desire (or ability) to run really long distances, I have learned to feel comfortable defining my goodness in running by the latter group of measures.
Regardless of how you define good, many of you want to be a better runner than you currently are. Many running experts point to various factors that you can train or adjust to be a better runner. Some of the factors that can be trained to improve running are referred to as “Intrinsic Factors,” or, in other words, factors within yourself that are modifiable through training. These include key aspects of running such as VO2max, Lactate Threshold, and Running Economy (which itself includes things such as foot type, foot strike, stride length, muscle strength, flexibility, etc), as well as motivational factors that determine drive, consistency, and persistence.
The next few blog posts will briefly discuss these factors and give some tips on training. With these blog posts I’ll attempt to break these factors down one at a time to give you a basic understanding of the factor, some options for training, and some food for thought.
Most runners have heard the term VO2max, but they don’t know much about it. By definition, VO2max is the maximum capacity of an individual's body to transport and use oxygen during incremental exercise (or exercise that gets progressively harder and harder). In a nutshell, VO2max reflects the physical fitness of an individual. The higher the VO2max, the better.
While a person’s VO2max is primarily genetically predetermined, each of us has the capacity to train and improve our VO2max to a certain degree. VO2max is determined by the supply of oxygen to our muscles and the ability of the muscles to use it. Supply of oxygen relates to our lungs’ capacity to pull in oxygen from the air and make it available to the blood stream as well as to our heart and blood vessels’ ability to take the oxygen to the muscles. Someone who’s heart can’t pump as fast or hard during exercise or who’s arteries can’t absorb increased blood flow will be limited in their VO2max. Once the oxygen gets to the muscle, muscle cells have to be able to pull it out of the blood stream and use it to produce valuable energy.
Factors that affect VO2max in our bodies include the following:
- Age—our VO2max declines slowly as we age (~10% per decade).
- Sex—generally, males have higher VO2max than females. The average untrained but healthy male has a VO2max around 35-40, while the average untrained female’s is 27-31. Elite athletes can achieve VO2max levels in the 85-95 range for males and 75-85 for females.
- Body size/composition—generally speaking, the bigger your body, the greater your VO2 max is likely to be. Larger people have larger hearts and lungs, and therefore more capacity for oxygen.
- Muscle type—each of us has genetically-determined levels of slow-twitch and fast-twitch muscle fibers in our bodies. Slow-twitch fibers have more energy-producing factories called mitochondria and are better able to use oxygen to provide energy than fast-twitch fibers.
- Altitude—the higher the altitude, the lower the VO2max because lower air pressure makes oxygen less available.
- Temperature-- VO2max tends to be lower for people living in more temperate or tropical areas.
VO2max can be estimated with mathematical formulas, but it is most accurately measured directly for an individual in a running or physio lab. During testing, exercise intensity is progressively increased while physiologists or doctors measure oxygen and carbon dioxide concentration of your inhaled and exhaled air. VO2 max is reached when oxygen consumption remains at steady state despite an increase in exercise workload.
Just knowing your VO2max is not as important as knowing what running speed/pace produces your VO2max and how far or long you are able to maintain VO2max. These variables can be measured in a running lab as well and give you valuable information to create or adjust your training plans. You can also roughly estimate your VO2max and these pace and time variables by using a rating of perceived exertion (RPE) scale or measuring your heart rate during exercise.
RPE is a recognized way to adjust a workout to train different variables including aerobic endurance, lactate threshold or VO2max. There are several scales used to assess RPE. One scale called the Borg scale) runs from 6-20. The numbers relate to phrases used to rate how easy or difficult you find an activity. For example, 6 (nothing at all) would be how you feel when sitting in a chair; 20 (very, very heavy) is all-out maximal exertion during an activity. The seemingly odd range of 6-20 is to follow the general heart rate of a healthy adult by multiplying by 10. For instance, a perceived exertion of 12 would be expected to coincide with a heart rate of roughly 120 beats per minute.
6 No exertion at all
7 Extremely light
9 Very light
13 Somewhat hard
15 Hard (heavy)
19 Extremely hard
20 Maximal Exertion
If you are training or competing at a high level of exertion (15-20), you are training or using your VO2max. After a thorough warm up, you can exercise in this RPE range and see how long you or how far you can sustain it.
To assess VO2max based on heart rate (HR), you need to either measure or calculate an estimated HRmax. This is the maximum heart rate your body can achieve and can be measured during a maximum intensity workout or estimated roughly by subtracting your age from 220 +/- 5 beats. For example, I am 40 years old, so my estimated HRmax would be 180 +/- 5 beats (175-185). The variability depends on previous training and other genetic factors. VO2max typically is met when exercising at about 90% of HRmax. Using my example above, when my heart rate reached ~162 beats per minute during exercise, I would be exercising at my VO2max. Measuring heart rate during exercise is now very easy with inexpensive heart rate monitors.
VO2max can be trained, but the amount of training varies depending on genetic factors. Some people will train and train with only smaller improvements in VO2max compared to others who train less. To train VO2max, workouts need to be done at a high intensity (90-100% of VO2max if previously measured, >90% HRmax, or above RPE “very hard”). For most beginner or intermediate runners, this intensity level corrolates with how fast you could run a 3k or 5k (1.85-3 miles).
Typical VO2max training workouts are shorter distance/time workouts done in intervals. Three examples of good VO2max workouts are as follows:
30/30 AND 60/60 INTERVALS
Start with 30/30 intervals. After warming up with at least 10 minutes of easy jogging, run 30 seconds hard. Then slow to an easy jog for 30 seconds. Continue alternating fast and slow 30-second segments until you have completed at least 12 and as many as 20 of each.
Increase the number of 30/30 intervals you complete each time you do this workout, and then switch to 60/60 intervals. Start with at least six of these and build up to as many as 10.
Shorter hill intervals of 20 to 90 seconds are great for developing power, strength and speed. Slightly longer intervals of two to three minutes are great for VO2max development. To do a hill intervals workout, warm up with at least 10 minutes of easy jogging. Then run hard uphill for two to three minutes (choose your duration before you start), jog back down to your starting point and repeat.
If your fitness level is modest, start with a set of 4 x 2:00 or 3 x 3:00. Very fit runners can do as much as 10 x 2:00 or 7 x 3:00. Pace yourself so that you neither slow down through the workout due to early fatigue nor finish the workout feeling you could do more.
400, 800 or 1200 METER INTERVALS
It may be easiest to do this type of workout on a treadmill or track where it’s easy to keep track of distance (one lap = 400m). Warm up with at least 10 minutes of easy jogging and then run hard for 400 to 1200 meters. Now reduce your pace to an easy jog for 400 meters.
Run shorter intervals (400m) in your first lactate intervals workout of a given training cycle and then move upward. Do a total of about 4-5000m of fast running in these workouts (10-12 x 400m, 6-7 x 800m, 4 x 1200m). Again, try to run the fastest pace that you can sustain through the last interval without slowing down.
As you train your VO2max, the body adapts by increasing the supply of oxygen to your muscles and improving the muscles’ ability to use the oxygen. You will then be able to sustain your pace over a longer run.
If you are interested in learning more about VO2 information or are interested in being tested contact our Bountiful Running Lab for details.