During the Olympics, the sports that get the most viewing time generally have one thing in common, and that is speed. However as we focus in on acrobatic and fast paced sports we are overlooking a different kind of world-class athlete. Endurance sports may not be as exciting to watch, but for a coach or trainer, putting together programs that improve endurance is a lot of fun. Endurance sport requires different energy systems, different central and peripheral adaptations and an entirely different tactical approach to racing. During this two part series, I will be discussing the physiology behind improving both endurance performance, and improving power sport performance.
VO2 Max
VO2 max refers to the maximum capacity of oxygen that an individual’s body can transport and use during maximal intensity exercise. There is a strong correlation between individuals who have a high VO2 max score, and individuals who place well in aerobic endurance sport. VO2 max can be modeled by the Fick equation. Within the Fick equation lies the secret to improving VO2 max.
VO2 max = Q x (aVO2)
Q = cardiac output
aVO2 = arteriovenous oxygen difference
aVO2 Difference
In layman terms, the aVO2 difference is the difference between the amount of oxygen that enters the cell, and the amount of oxygen that leaves the cell. Therefore, a high aVO2 difference indicates that more oxygen is removed from the blood through the capillaries and utilized for metabolic processes within the cell. While VO2 max is a measure of how much oxygen the body can use at maximal intensity exercise; the aVO2 difference shows how efficiently the cell can absorb and use oxygen. The aVO2 difference can be calculated by using the following formula.
aVO2 = Ca – Cv
Ca = the oxygen concentration of arterial blood (oxygenated blood)
Cv = the oxygen concentration of venous blood (deoxygenated blood)
Cardiac Output
Cardiac output (“Q” in the Fick Equation) can be modeled through a simple equation.
Q = SV x HR
SV (stroke volume) = the amount of blood pumped per beat.
HR (heart rate) = the number of times the heart beats per minute.
Once these three equations and there relationships are understood, we can begin to identify ways in which improving VO2 max.
Below is a modified Fick equation.
VO2 max = (Stroke Volume x Heart Rate) x (Arterial Oxygen Concentration – Venous Oxygen Concentration)
Improving Endurance – Long Term Athlete Development
To maximize cardiac output capacities it is advisable to focus heavily on developing an aerobic base during the “Training to Train” phase of the LTAD model. Be observant for the onset of Peak Height Velocity (PHV), by continuously recording measurements of the athlete’s growth. When the athlete is growing at his/her fastest rate they have attained Peak Height Velocity. During the onset of Peak Height Velocity, training should be centered around developing a strong aerobic base. PHV is a strong indicator of hormonal changes occurring in the pubescent athlete. During this “window of opportunity”, coaches can take advantage of anabolic hormones such as HGH to help improve cardiac output. By training the aerobic energy system, stroke volume will increase as the cardiac muscle of the pubescent athlete will strengthen and hypertrophy.
Improving Endurance – Energy System Development
Once the “window of opportunity” created during the onset of Peak Height Velocity is maximized, coaches can now either specialize the athlete and focus on aerobic training, continue multi-lateral development and focus on both aerobic and anaerobic, or singularly focus on anaerobic training. Similar to weight training, the intensity dictates the training adaptation. With strength training we refer to intensity as % of 1 repetition maximum, with energy system training we refer to intensity as % of maximum heart rate. Energy System Development (ESD) is a system designed to more clearly define the training adaptations that certain ranges of heart rate max provide. Once the ESD system is understood, improving VO2 Max and improving performance becomes instrumentally easier and more efficient. See the diagram below to view the different adaptations that occur in varying ranges of % of max heart rate.
3 Training Recommendations for Improving Endurance
- Train with specificity
- Aerobic training adaptations require longer duration sessions
- Aerobic training takes place at lower intensities, therefore can be trained more frequently without significantly depleting the central nervous system.
In the second part of our two-part series on improving endurance and power sport performance, we will discuss how energy systems work, and how to train for maximal power output.
References
Canadian Sport for Life (2012) Long Term Athlete Development. Retrieved August 2nd, 2012 from www.canadiansportforlife.ca
ACE Fitness (2012) The Fick Equation. Retrieved August 2nd, 2012 from http://www.acefitness.org/blog/1545/the-fick-equation