Speed is rarely the limiting factor in how fast you can race, even for a distance as “short” as the 5K.
The first step to improving is almost always identifying your strengths and weaknesses. Whether it be preparing for a job interview or dropping your 5K PR by 30 seconds, identifying the areas that need the most work allows you to dedicate your time to the activities and training that will provide the most value.
The difficulty lies in accurately targeting the right weaknesses, especially in running where what you feel doesn’t always correlate with what is happening physiologically in your body. For example, the heavy, cement-like feeling in your arms and legs at the end of a 5K isn’t a sign of muscle weakness or that you need to spend time in the gym. Rather, this feeling is caused by the release of hydrogen ions when racing beyond your anaerobic threshold, which creates an acidic environment in the muscles and impairs muscle contraction. This is why runners are better served hitting the roads for a tempo run than they are hitting the weight room if they want to avoid fading at the end of a race.
Perhaps the most often misunderstood concept of training, and the most difficult for runners to identify where their weakness might be, is aerobic endurance versus speed. Because it’s often difficult to “feel” aerobic endurance, it’s easy to think that not being able to kick the last 800 meters of a race or not being able to race faster at shorter distances is due to a lack of speed. This is why so many runners turn to the track for lung-busting 400′s to help them get faster.
Unfortunately, if you’re approaching training this way, you may be focused on the wrong weakness and thereby not maximizing your training time or your workouts. In the following pages we’ll examine how speed and aerobic endurance influence your performance on race day.