For runners like Thomas Datwyler, the road to running marathons includes transitioning from shorter race distances like 5k and 10k courses. With the 5k, the competitive runner needs to run the full 3.1-mile course at near to maximal effort throughout. With the entire course typically taking 20 to 30 minutes to complete, all but the most in-shape runners will start to redline, or feel intense exhaustion that they must push through, at around the 1.5-mile mark.
The key to the latter stage of the 5k is increasing speed endurance, or ability to maintain a fast pace without stopping. Part of this relates to VO2 max (with V standing for volume and O2 for oxygen). This quantifies the amount of oxygen the body consumes during sustained exertion and is measured in milliliters of oxygen consumed for each kilogram of body weight, for each minute of exercise (ml/kg/minute).
Underpinning VO2 max is the process by which lungs take in and absorb oxygen, transporting it to various muscles and organs. Muscle cells require oxygen for producing adenosine triphosphate (ATP), their primary energy source. This is a major reason one breathes faster when exercising — more oxygen intake equals more ATP generated by muscle cells.
Runners like Thomas Datwyler, with a higher VO2 max, have hearts and lungs able to more efficiently supply the muscles with blood, with muscle cells more efficient in extracting this oxygen for ATP production.
Improving VO2 max starts with simply getting the heart pumping at a more rapid rate regularly, through techniques such as high-intensity interval training (HIIT). This alternates short bursts of intense exertion with longer-duration cool-down periods of moderate exertion.
It’s also critical to switch up the workout routine, whether through swimming instead of running once or twice a week or ramping up to maximum effort quicker in a workout session. Both get the body off balance, forcing it to adapt and boost ATP production. Additionally, simply losing weight increases VO2 max.
Another key element of speed endurance is working on aerobic capabilities through sustained effort over an extended period. This differs from fast-burst VO2 max workouts. Both techniques can be combined. For example, one can run six 800-meter segments at maximal 5k pace, interspersing each fast-burst with 200 meters of brisk jogging. The latter provides rest and recovery and is around 80 percent of marathon pace.
Those who have mastered a 5k distance without too much effort often find they cannot keep this exertion level through a full 10k course. They tend to hit a brick wall around 70 percent of the way through and slow considerably. A major reason for this is that, while 5k races are around 84 percent aerobic, the aerobic component shifts as high as 95 percent during the 10k.
Training for this involves integrating longer runs that test limits in the weeks leading up to the race and learning how to pace oneself. Instead of 6x800m with 4:1 rest, as with 5k training, one shifts to 8×1,000m, with 2:1 rest. This involves greater distance, more reps, and double the brisk-jog rest between each section of maximal exertion. This helps the runner build toward maintaining goal pace while moderating exertion in ways that manage fatigue and its corresponding stresses.
