Pulse oximeters have long been standard equipment in hospitals, but it is only lately that they have been widely accessible to athletes. When you live or exercise at high altitudes, or if you have a tendency toward overtraining, the capacity of your body to metabolize oxygen is a critical aspect of your performance. In this article, we'll look at how these tools function and how you may best put them to use.
A pulse oximeter estimates the amount of oxygen bound to hemoglobin in the blood and displays the results as an oxygen saturation (SpO2) reading. Pilots and others who often operate or exercise at high altitudes utilize pulse oximeters because of their small size, portability, lack of invasiveness, and discomfort. You may get a precise reading by clipping it onto your (or your athlete's) finger.
Oxygen binds to hemoglobin in the lungs, a protein in red blood cells. Oxygen is distributed throughout the body through the circulation and picked up by the red blood cells. The average person requires roughly 550 liters of oxygen daily, but this number may increase by as much as three times during strenuous physical activity. Blood oxygen saturation levels are maintained at about the same level during light to moderate activity as during rest. When exercising at a greater intensity (particularly during maximal aerobic intervals of roughly 3-6 minutes in length) or training at considerably higher altitudes than you are used to, your blood oxygen levels may decline, although only slightly. The more you exercise, the more effectively your body will use oxygen.
A pulse oximeter measures the amount of oxygen in your blood by shining (usually red and infrared) light through one side of your finger and onto a photodetector on the other. Your blood cells absorb light differently depending on whether they contain oxygen when it travels through your finger and into your veins. The quality of the light that reaches the photodetector may determine the amount of oxygen in your blood; typical values are between 94% and 100%.
Many varieties of pulse oximeters exist, each with its specialties. Some are made specifically for medical settings, while others may benefit an athlete's game more.
In addition to your typical training metrics, checking your Peripheral Saturation of Blood Oxygen (SpO2) levels may tell you whether your body is recuperating as it should.
Here's an example: the athlete who woke up "not right" after a particularly strenuous training block. His TSS for Tuesday's training shows the obstruction. The fact that he was sleeping less than seven hours a night only made matters worse. His morning SpO2 was indeed low, measuring in at 93%. It's a perfect example of an athlete who may believe he is well enough to go workout but whose poor sleep hours and low SpO2 back up his claims of "not feeling right."
This athlete decided to take the following two days off from training and concentrate on rest and recovery instead (he slept for a combined total of 9 hours over two nights). His blood oxygen level eventually returned to normal, and the following training sessions were productive. Careful attention to the relevant statistics may help ensure the success of a training block and the avoidance of overtraining.
At a higher altitude, oxygen can't travel as far to reach your muscles and organs. At an altitude of 10,000 feet (3000 meters), for instance, there is only approximately 15% as much adequate oxygen in the air as at sea level (21%). If you usually reside at sea level, the reduction in oxygen pressure will cause a cascade of physiological changes, some of which will benefit you in a race at any altitude. Your breathing and pulse rates will speed up initially, and your heart's ability to pump blood out (stroke volume) will diminish.
Blood plasma volume is decreased over the first 48 hours at altitude to increase the blood's oxygen-carrying capacity per unit of volume. These adjustments won't feel great; you could feel like you're putting in more effort for less payoff.
Blood volume and arterial oxygen content may be partially or fully restored after extended exposure to altitude due to the body's increased synthesis of red blood cells with bigger hemoglobin. Exercising for four weeks or more means your heart won't have to pump as quickly or hard since your blood will carry more oxygen.
Once you've adapted to the altitude, your peak oxygen consumption will be the same at sea level, but your arterial oxygen saturation will be higher. You may continue to compete, train at higher altitudes, and even find more aerobic endurance at lower elevations.