Saturday, December 10, 2016

Effects of Age on Oxygen Uptake Kinetics

After exploring a few ways athletes can improve their VO2max, we have learned that coaches and athletes can maneuver around limitations a human’s physiology might have. Despite all the adaptations, training methods, and ergogenic aids an athlete may have access to, there is one thing that they cannot escape. Age.
Physiological responses to exercise have age-related differences between the young and the old. VO2max will decline with age without regard to whether or not an individual is trained or untrained.1 A study by Grey et al. showed that untrained young, middle age, and older individuals had a VO2max of 50, 45, and 30 ml•kg-1•min-1, respectively. Trained young, middle aged, and older individuals had a VO2max of 67, 55, and 45 ml•kg-1•min-1, respectively. 1 Although there is a significant difference in values in the corresponding ages, there was still a decrease in VO2max. An individual can lose around 1% of maximal aerobic power per year from its peak value (age 20 – 40 years). 2 In an earlier blog, we learned that VO2max (maximal aerobic capacity) is determined by the uptake of oxygen of the tissues as well as cardiac output.2 Aging causes a decline in maximal cardiac output and maximal a-v O2 difference, which both contribute to the decline in VO2max.2

Although long-term endurance exercise cannot halt the declining effects of aging on VO2 max, it can slow it down. Long-term endurance training can prevent the slowing of VO2 kinetics. This is shown by the absence of age-related slowing of VO2 kinetics, presented by the oxygen delivery to oxygen utilization ratio in trained older individuals.1 As a result, the trained older individual will experience a lower decline in VO2max.1
No one can outrun the effects of age, but with the help of long-term endurance training, it can be slowed down. An individual's VO2max will decrease without regard to if they are trained or untrained, but the individual who is trained can prevent the slowing of VO2 kinetics.1 For the majority, a decline in VO2max is usually due to a decline in physical activity. With this decrease comes a decline in being able to engage in physical activity comfortably. This initiates a snowball effect and affect quality of life, and could lead to even more health problems.2 Things like asthma, bronchitis, and emphysema can also cause a significant decrease in oxygen uptake kinetics. This will be discussed more in the upcoming blog.
1Grey, T. M., Spencer, M. D., Belfry, G. R., Kowalchuk, J. M., Paterson, D. H., and Murias, J. M.     Effects of Age and Long- Term Endurance Training on VO2 Kinetics. Medicine & Science In Sports & Exercise. 2015; 47 (2); 289-298.
2Powers, S.K. and Howley, E. T. Exercise Physiology. Theory and Application
 to Fitness and Performance. 2015; (9): 383-386, 509-512.

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