Endurance is essential in almost every sport. And as a strength coach, it's your job to prepare your athletes for the demands of their sport. So you need to understand the physiological determining factor of endurance, and how to optimize it.
What is VO2 Max?
According to the American College of Sports Medicine (ACSM), cardio-respiratory fitness is determined by oxygen consumption, technically called VO2. This is measured by how much oxygen (in milliliters) your body can use per kilogram of body weight per minute. (Learn more about the body's energy systems.)
VO2 max is the maximum amount of oxygen the body can use, and it directly correlates to fitness capacity. An athlete with a VO2 max of 65 ml/kg/min will be able to perform at a high level for a longer duration than an athlete with a VO2 max of 40 mL/kg/min. However, this relates to aerobic work. Someone with a high VO2 max will not necessarily be able to perform at a higher capacity during resistance exercise or short-duration high-intensity work, such as sprints.
How is VO2 Max Found?
VO2 max can be found with a metabolic cart system. The athlete wears a mask, and the machine measures the chemical difference between inspired and expired air. The athlete is then taken through the Bruce Protocol Graded Exercise Test (GXT), which progressively challenges the body by increasing intensity over time. The instructions are below:
If you don't have access to a metabolic cart, VO2 max can be estimated with the 1.5 mile run test. It's not as accurate, but it's better than having no baseline.
Formula: VO2 max = 88.02 + (3.716 X Gender*) - (0.0753 X Kilograms of Body Weight) - (2.767 x Time in minutes and fraction of a minute**)
* Gender: Male = 1; Female = 0
** Example: 2 minutes and 15 seconds = 2.25
Establishing a baseline VO2 max is critical for any endurance training program. It allows you to determine your athletes' level of fitness, similar to a one-rep max for a resistance exercise. You can then design a program using various endurance training methods, and test their progress with subsequent max tests.
Increasing VO2 Max
It is possible to increase VO2 max by regularly performing exercises that challenge the cardiovascular system by increasing endurance training volume and intensity over time. Full-body rhythmic movements, including running, cycling, swimming and rowing, are effective ways to do it. It's important to vary the type of endurance training to continue challenging the body, similar to how you can't have an athlete perform the same exercise every workout. (See a sample marathon training program.)
Another increasingly popular way to increase VO2 max is interval training, which includes short periods of vigorous exercise interspersed with short rest periods. The Tabata protocol is extremely effective, as are high-intensity interval (HIIT) workouts, similar to the program below.
HIIT VO2 Workout
Instructions: Perform each exercise for 30 seconds. Rest for 15 seconds between exercises. Repeat 2-4 times for a total of 8-16 minutes of vigorous activity. This can be modified to fit various fitness levels.
- Warm up for 10 minutes
- Mountain Climbers
- Burpees (or Iron Cross if available)
- Glute Bridge Marches
- Lateral Hops
- Jump Squats
Cool Down with a light 10-minute jog followed by a thorough head-to-toe stretch.
Source: ACSM, University of Alaska
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