Unless a runner is on a very long run or exposed to considerable ambient heat in a training session, most fatigue can be traced to the effects of acidosis, i.e. hydrogen ion+ produced deterioration of performance. Many examples of acidosis are obvious, such as watching a runner trying to complete a set of eight fast 400 meter repeats with incomplete rest between each bout of work. Other examples of hydrogen ion fatigue are not so obvious, such as trying to explain to a runner why they are not faster in a ten-mile race. Designing tempo and lactate threshold work sessions are our focus here.
Glucose, reduced in the absence of oxygen, is constantly converted to useable ATP energy by animals. It is one of the characteristics of life. Blink, snap your fingers, raise your arm, or tap your feet quickly and one is producing positive hydrogen ions and negative lactate ions from the inefficient conversion of carbohydrate to ATP without the presence of oxygen–outside the mitochondria of the cell.
In these examples, the hydrogen ions are quickly buffered by agents in the blood. However, in running we need to pick up the pace so the hydrogen ions are not so quickly buffered. When running intensity reaches a certain level, buffering can no longer neutralize the hydrogen ions and the acidity of fluids in the body begins to increase.
Acidity affects enzymes and slows biological processes. A little bit of extra acidity above this clearance threshold can be tolerated for a time, especially by a well-conditioned distance runner, but eventually too much hydrogen ion accumulation causes acidosis and thus fatigue leading to exhaustion leading to cessation.
The threshold of clearance vs. non-clearance of hydrogen ions is called the lactate threshold or anaerobic threshold. This threshold, like many other biological processes, is altered by specific kinds of distance training. After several weeks of distance training, it is usually seen that it takes a faster running velocity to reach the lactate threshold (LT).
On a treadmill in a human-performance laboratory, a scientist can determine a runner’s present-day LT and thus assist a track coach in determining training velocities that can improve the LT of that runner.
In the absence of a lab test a coach can basically field test or estimate what an athletes nine-mile to exhaustion date pace would be and thus determine workout velocity from that value. In essence, LT is the pace that a runner competes at in a competitive 15 Kilometer race. This pace would show about 3.0-3.5 mmol/L of lactate in most conditioned runners (scientists measure lactate values to determine hydrogen values because the measurement field test for a coach is much easier and lactate levels directly correlate to hydrogen levels, i.e. high lactate ion levels = high hydrogen ion levels while low lactate = low hydrogen).
Delaying fatigue in a middle distance runner is the main objective in training. The primary function of the coach is to design workouts that over time will allow an athlete to both tolerate high amounts of acidity and to increase the training velocity that correlates with the LT.
All distance-type, longer running sessions, help to improve the LT for a while, however a point is eventually reached in conditioning when just running distance at slow speeds is ineffective in moving the LT. At this important juncture in training, running at velocities corresponding to the LT pace is the most effective way of continuing to improve the LT.
There are two workout modalities used in middle distance training to move and also improve the LT; they are called the LT run and the tempo run. Interestingly, both the LT run and tempo run are done at the same date pace – present day LT (3.0-3.5 mmol/L) pace. The difference lies in the duration of the two training modalities. Because the duration of the two is different; they will each occupy a difference place in the middle-distance macrocyle, and they will differ considerably in their workout recovery length.
Neither the LT run or tempo run are part of the general preparation period for a middle distance runner. The LT run is a training session in all of the microcycles of the specific preparation period and is then replaced by the tempo run in the microcycles of the pre-competitive period, and then this modality too disappears during the competition period.
The LT run can be done continuously or interval style by middle distance runners. By definition the LT run can be done to nine miles at an exhaustive pace. Few middle distance runners would do the workout to this length as the recovery from it could take 4-5 days.
By shortening it, but keeping the pace the same, the recovery period would be much shorter and it would still give plenty of stimulus for a middle distance runner during specific prep. A six mile run done at LT pace (3.0-3.5 mmol/L or 85% of vVO2 max) would be an ideal length, and an athlete would recover for the most part in 48 hours.
Many middle distance runners could not do this work session continuously so it would have to be broken down into intervals to get the desired stimulus. Depending on the skill of the athlete, the work bouts could be 400s, 800s or even miles, all done with short rest intervals of 15-30 seconds between the work; same pace same total distance.
The tempo run is a regular work session found later in the macrocycle; mostly during pre-comp microcycles. The pace is faster than earlier LT runs because vVO2 max is faster toward the end of the season, but the percentage of vVO2 max pace remains the same as LT runs at 85% of date pace.
A tempo run should last about 25 minutes. For a high school male that is about 4.5 miles and for a high school girl about 4 miles. If the pace is proper for each runner, recovery should be about 36 hours.
The tempo run can be done continuously or as an interval-style work session. If done as intervals try to do it as 800s or miles with about 20 seconds rest intervals between each bout of work holding the proper pace throughout the workout. If lactate was to be checked within 30 seconds of completion of a tempo run it should be 3.0-3.5 mmol/L which is the same as the LT run.
Lactate runs and tempo runs are necessary training components for every middle distance runner. A coach needs to determine when and how to implement both in order to fully develop the runner for competition.