This speed session will help keep your form and pace from fading at the end of a race.
Let me know if this statement sounds familiar: “I was holding a good pace for the first 2 miles, but then my legs started filling up with lactic acid the last mile and I was done.”
Heck, you may have even said this yourself when your smooth stride turned to a slow shuffle at the end of your most recent 5K. And while I don’t doubt that your pace plummeted faster than Felix Baumgartner fell from the edge of space, it wasn’t lactic acid that caused you to tie up and slow down.
The slow man’s shuffle you were doing in the final mile of your race was a result of your body’s inability to efficiently clear lacate — which along with hydrogen ions comprises lactic acid — from your blood faster than it could be produced. When you run fast, in this case 5K race pace, your muscles use lactate as a source of energy. The longer and faster you run, the more lactate your muscles produce, and subsequently use. As long as your body can clear lactate as quickly as it’s produced, your muscles will work efficiently and won’t have too much trouble maintaining your pace. When your body starts producing lactate faster than it can be cleared, however, everything starts going to hell—your legs get heavy, form starts falling apart and pace begins to fade—as hydrogen ions begin to slow energy reactions in your body and impair muscle function.
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So, it makes sense then that if you can improve your body’s ability to clear lactate while running race pace, you’ll be able to hold that pace for a longer period of time before both your form and pace begin to fade into oblivion. There are a number of workouts which can help you achieve this end, but for 5K and 10K training, the Broken Miles session is one of my favorite. Best performed on a track or interruption-free path or trail 3-6 weeks out from a key race, the Broken Miles workout alternates between 1,000 or 1,200 meters at 5K race pace and 600 or 400 meters at faster than 5K race pace, separated by a short rest between intervals and a longer rest between sets. Adjust the pace, and number of sets, for your fitness and experience level.
The Broken Miles Workout
— Warmup: Run easily for 20-25 minutes, dynamic warmup drills, 6 x 20-second strides
Version 1: 3 to 4 sets of 1,000m at 5K race pace, 60-90 seconds recovery, 600m @ 3K race pace. 3-4 minutes recovery between sets.
Version 2: 3-4 sets of 1,200m (or 3/4 mile) at 5K race pace, 1:30-2:00 recovery, 400m (0r 1/4 mile) at 1 mile race pace. 3-4 minutes recovery between sets.
— Cooldown: Run easily for 20-25 minutes