There is still some lingering soreness in my shins, calves, and upper thighs—but after doing an easy 6 miles today, I am feeling better. The slight tenderness in my legs constantly reminds me of my 5K last Saturday. I keep thinking of what I need to run faster at that distance. It’s not aerobic conditioning, that’s for sure. I didn’t feel like I was running out of oxygen during the race, not even in the final sprint to the finish. I can remember faster 5Ks in the 1990s where I was hyperventilating in the final stretch. I never felt I was at that point during the race. In fact, I felt like my breathing was fairly under control and there was no shortage of oxygen for my system.
What I did feel, though, was heaviness and burning in my legs, and a feeling that I just couldn’t make them move faster. So I suspect that I lack leg speed and, more importantly, a solid lactate threshold.
“A lactate what,” you might ask? Let me explain. There are at least two factors that contribute to your running success at distances ranging from the half mile up to the marathon. The first is your aerobic capacity, commonly measured by the oh-so-scientific-sounding VO2max; basically, this is the amount of oxygen your body can transport to your working muscles at any given moment. Some might think it is a matter of lung capacity, but the true limiting factor is actually your heart and circulatory system. The best way to improve VO2max and overall aerobic conditioning is to just go out and run lots of miles, preferably at a slower, conversational pace. All this running also has the added benefit of toughening up your bones and connective tissue and teaching you to run more efficiently, which ultimately helps you avoid the bane of all runners—injuries.
The second factor is that lactate-something-or-another-thingy—we will use the more scientific term, lactate threshold. Lactate is the stuff that your muscles produce when they are making energy from oxygen. Lactate is actually not bad stuff, since organs such as your heart and kidneys can use it as a source of energy. The bad stuff happens when lactate starts building up faster than your body can use it. The next thing to happen when this occurs is that the lactate binds with hydrogen ions, forming lactic acid. This is the bad stuff that makes your muscles burn and your legs feel heavy and non-responsive when you are running fast. The lactate threshold is the turning point at which your body starts to accumulate more lactate then it can deal with. If you can push back the threshold, you can run faster for longer without your legs falling apart.
How do you train your lactate threshold? Easy, you spend time running at your current threshold. The most common workout for this is called a tempo run. This is a run where you start with an easy warm up, run several miles right at your lactate threshold, and then finish with a cool down. To progress the run, you increase the time you spend at your lactate threshold by adding more miles—also, you will eventually find that as you get better, you will be able to run faster at your threshold.
To determine the pace that you need to run, you can take your most current 5K race time and add 30-40 seconds to your per mile pace. Another way to measure your lactate threshold is to wear a heart rate monitor and run at 80-90% of max heart rate. You should be able to hold this pace for one hour if running a race. Finally, if you are really crazy, you can buy lactate monitors that measure the lactate in your blood—you prick a finger. You can run some intervals on a track and measure your blood lactate while slowly increasing the speed of each interval to find the point where you blood lactate spikes. This last method is a little nutty, though, so I would just go with the 5K race time or heart rate monitor methods.
What this all means is that I will probably be doing some tempo runs within a couple of weeks once I stabilize my mileage at around 50 miles per week. I have also started doing some 100M strides to increase my leg turnover speed. We shall see what effect this all has on my 5K and 10K times. Stay tuned.
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