Authors: Patrick M Whitehead*
Patrick Whitehead is an assistant professor of psychology at Darton State College in Albany, Georgia. He has published widely in fields of psychology, philosophy, and biology. In his free time he is a recreational long-distance runner and coach.
Patrick M Whitehead, PhD
Division of Social Sciences
Darton State College
Albany, GA, 31707
This paper presents two arguments against the pace-based approach to running, defined as the reduction of training intensity to measures of distance/time (that is, pace). The experimental data of Daniels (5) is presented as an example of this. It is argued that the pace-based approach ignores many variables that are important in understanding the physiology and psychology of training long distance runners. The first argument examines the assumption that pace may be used as a general approximation of intensity. This ignores the role of confounding environmental factors like altitude, temperature, and wind. The second argument examines the assumption that any measure of intensity is as good as or better than another. Heart rate, blood-lactate levels, and volume of oxygen consumption are physiological markers that provide useful information for understanding levels of intensity, but their relationship is not certain.
KEYWORDS: Long-distance running, training, running by feel, Ratings of Perceived Exertion
In this paper, the author examines the assumptions that underlie the pace-based approach to monitoring exercise intensity. Such an examination is important because the pace-based approach dominates the training methodologies for athletes of aerobic sports. This paper will specifically review its appropriateness as a basis for monitoring effort levels for long-distance runners. Its purpose is to draw this practice into question, making space for alternative approaches, like those that emphasize running by feel (2,6,13,15). It should be of particular interest to endurance athletes and their coaches, as well as those in the exercise sciences.
The author argues that a pace-based approach to training long distance runners is misleading because it is built upon two problematic assumptions. The first assumption is that pace (i.e., physical velocity) may be conflated with intensity (i.e., a physiological expression of work—specifically VO2max, or the maximum amount of oxygen that can consumed by an athlete). The tenuousness of this assumption may be seen in how easy it is to manipulate the relationship between pace and intensity through a third variable. Altitude, temperature, and wind are provided as such variables. The second problematic assumption is that any measure of intensity is as good as or better than the others. While physiological markers of intensity (e.g. heart rate, blood-lactate levels, and VO2) are correlated, there is some uncertainty about their relationship with one another, as well as with their mediation of levels of exertion.
Physiology of Training
Beginning with the very first documented training logs, runners have been searching for the methods that maximize running fitness (16,18). Such methods have been established through decades of experimental trials that evaluate the importance of various aspects of training such as volume (time and distance), rest and recovery, velocity, intensity, elevation, and of related elements such as nutrition, footwear, gear, and so on.
When looking specifically at the development of running fitness, there are physiological thresholds that long-distance runners confront in training that limit how quickly they can cover a particular distance. Training is engineered to target each of these thresholds. Thresholds may be experienced subjectively by increases in perceived effort (3), or operationalized into specific zones of intensity (16). Despite the use of operationalized zones of intensity in training programs, Seiler and Kjerland (18) argue that “these numerous intensity zones suggest a degree of physiological specificity that is not really present” (p. 49). This is an important detail that will be emphasized below.
The most basic physiological marker of intensity is the number of times the heart beats in a one-minute period—that is, one’s heart rate (HR). As exercise intensity increases, HR increases from resting and up towards its maximum level. Since the blood plays an important part in delivering oxygen and nutrients, as well as clearing waste away from working muscles, the HR plays an important role in mediating this process.
Intensity may also be measured by way of blood-lactate levels. During work, muscles produce lactic acid which needs to be cleared away as waste or metabolized as energy. If work is intense enough, the blood cannot clear the lactic acid away fast enough and it begins to accumulate. Thus, levels of blood-lactate can indicate intensity of exercise. Indeed, Kindermann et al (14) have developed three training zones separated by two physiological lactate thresholds, calling these the aerobic and anaerobic thresholds (18). In the first intensity, there is no accumulation of lactic acid in the blood. This is the pace at which the lactic acid created by working muscles can be comfortably removed or metabolized as an energy source. A runner crosses into the second zone of intensity when lactic acid begins to accumulate in the blood. This first threshold has been called the aerobic threshold (LT1). The runner crosses the second threshold—the anaerobic threshold (LT2)—and into the third zone of intensity when lactic acid reaches maximum level (4.0 mM). This is the period when muscles have a burning sensation and fatigue sets in rapidly.
Intensity thresholds have also been found in ventilatory mechanisms. Ventilatory Thresholds (VT1 and VT2) are determined by the amount of oxygen that is consumed during exercise (as measured by breath-by-breath gas-exchange monitors). This is measured in volume of oxygen or VO2. The maximum amount of oxygen that an athlete can consume is referred to as their VO2max, a term that will be used below. When oxygen consumption is mapped alongside blood-lactate levels and heart-rate (HR), there are strong positive correlations (18).
Psychology of Training
The importance of psychological elements of training are also well documented, and emphasized by many coaches and exercise physiologists. This section will examine the use of psychological principles as they have been employed by the training philosophy of Joe Vigil—exercise physiologist and one of the greatest Olympic and Collegiate coaches in American history, and Tim Noakes—kinesiologist and author of widely distributed and read book Lore of Running.
Runners who have trained under Joe Vigil understand that the sport is deeply psychological (22). Among the axioms of his training program, Vigil places “Improve personal relationships,” “Improve achievement motivation,” “Improve maturity” and “Show integrity to value system” (np). Before they begin training, Vigil (21) writes,
[O]ur athletes would do one thing. They would take a long and thorough look at what they wished to achieve, how they thought it could be achieved and how long it would take them. The time that we spent in individual and team meetings, surveying our ambitions, was time well spent. (p. 4)
By putting training in perspective, athletes begin to understand a paradox in training as a long-distance runner: that more is not always better. Indeed, too much too soon inevitably leads to injury or burnout, lengthening the process for gains in fitness.
Kinesiologist Tim Noakes (16) also recognizes the value of the psychological aspect of the sport. For example, he writes that “[d]espite all that I have written about preparing the body for running, I suspect that the preparation of the mind is the more important factor determining running success” (p. 514). Noakes credits the finish of the 1996 Olympic Marathon for solidifying the importance of psychological components in running success. “Irrespective of physical ability,” Noakes explains, “it was the athlete who was emotionally dominant who won” (p. 525).
Physiological-psychological Interaction in Training
As presented above, physiological and psychological aspects of training have been kept separate; but there is plenty of evidence that indicates an interaction between them. Beedie and Foad (1) describe the mind-body interaction in sports as it may be seen in placebo studies. They explain how Foster et al (7) have found that five-kilometer running performance increases when athletes believe that they have consumed an ergogenic aid. Clark et al (4) have found that cyclists perform better when they thought they had consumed carbohydrate than those who had actually consumed carbohydrates (yet thought there was a chance that they had not). When looking at the mind-body interaction, one must eventually consider what this means for performance as Hurst et al (12) have done. As long as the conversation keeps these two parts separated, important aspects are being ignored.
That which has been summarized above is by no means a comprehensive account of the physiological, psychological, and psycho-physiological elements that come together in the mediation of effort levels (8). Their brief consideration is in service to the recognition that the mediation of effort while running is supremely complicated, and that its reduction to any single marker is going to be fraught with difficulty.
The Pace-based approach to Training is Misleading
The distance running literature has so privileged pace-charts as the quintessential measurement of exertion that it is difficult to imagine any alternative to this. The charts supplied by training methodologies presuppose the importance of pace—distance divided by time (e.g. kilometers/hour), with requisite adjustments made after this has been established (for elevation, terrain, extreme temperatures, and so on).
Exercise physiologist Jack Daniels (5) provides complete training programs tailored to a variety of ability levels as well as distances. He outlines workouts that employ five primary training levels that correspond with physiological intensity (which he calculates based on measurements of %VO2max [maximum consumption of oxygen] and %HRmax). Each runner has a specific pace (minutes/kilometer) that corresponds with each of these training levels. Daniels explains his reasoning for the five paces:
The relationship between velocities and intensities is extremely useful; it signifies that if vVO2max [velocity at which one reaches one’s maximum consumption of oxygen] can be identified, there’s no need for VO2 max or economy testing for the purpose of setting training intensities. Fortunately, current vVO2max can be closely estimated from knowing the race performance capabilities of a runner. (p. 31)
Introducing the velocity component provides an opportunity to connect laboratory-measured levels of intensity with easy-to-monitor measurements outside the laboratory—e.g. speed. Instead of targeting a particular VO2 while running, a runner may monitor splits on a 400m track with a stopwatch, or off of the track with a Global Positioning System watch which provides data fields for current and lap paces.
The argument against the monolithic, pace-based style of training is twofold: (1) velocity is not synonymous with VO2 or any other marker of intensity; (2) one measure of intensity is not “the same as” or “better than” the others.
Argument One: Pace is not Synonymous with Intensity
Daniels’ (5) preference for pace-based training may be seen throughout his work. In it one finds a great variety of charts where paces may be found corresponding with athlete ability, race distance, duration, and so on (e.g. Tables 3.1, 3.2, 3.3, 7.1, 7.2, and so on). While Daniels may be the most notable example of the pace-based approach, his is by no means the only one to treat training this way. Vigil (20), quoted above, has published a vVO2max chart (Table 2.6), and lists target paces alongside each of his workouts. Even the self-proclaimed “Renegade” methods of the elite coaches Keith and Kevin Hanson have defined workouts in terms of target-paces, providing a unique chart for every workout listed (11). Higdon’s (10) Marathon was one of the few training books that did not emphasize pace when describing the training of a distance runner. He admits, however, that this information can be found in one of his earlier works (9).
It seems so simple: find one’s level of fitness based on a performance time at a particular distance (by looking at a chart), and use this to determine how fast one needs to run one’s workouts and races. How could the author possibly argue that this complicates the process? On the surface, the emphasis on pace has the advantage of simplifying the concept of exertion: indeed, it replaces exertion (subjective felt sense) with intensity (physiological marker). Intensity as a physiological measurement is once removed from exertion which is a subjective felt-sense. Intensity is the physiological expression of exertion. As an abstraction of exertion, it fails to take into consideration the manifold psychological components that mediate the experience of effort during exercise. Emphasizing pace goes one step further: the measurement of pace is once removed from intensity (which is once removed from exertion). Pace corresponds with intensity only when every other variable remains constant. This, of course, is an unreasonable expectation. Consider just three additional variables that influence the relationship between intensity and pace: heat & humidity, elevation, and wind. These three by no means summarize the additional physical variables that shape the relationship between pace and intensity, but they should begin to demonstrate the argument that pace-based training introduces unnecessary complications.
Heat. The relationship between pace and intensity is influenced by heat (and humidity). This occurs through a decrease in blood-volume through perspiration as well as an overall increase in body temperature (which decreases performance).
Vigil (22) summarizes the effects of training in a hot environment: Hyperthermia causes 1) the dilation of skin blood vessels and the pooling of blood in the appendages, 2) increased heart rate, 3) decreased muscular blood flow, and 4) reduced cardiac output. All of these mechanisms result in circulation strain and produce the onset of fatigue. (p. 183)
As heat increases, the body must increase perspiration in an effort to dissipate the resulting body heat. As sweat drips off (through evaporation or simply by dripping off), blood volume decreases. Lower blood volume results in an increased heart-rate.
More specifically, when body temperature is raised from 98.6 degrees to 102 degrees or higher, “performance begins to suffer, and you definitely start to feel worse” (5, p. 104). Daniels continues, explaining how “runners usually learn to recognize this limit…and back off when increased temperature makes them feel bad” (p. 104). He concedes that when weather is a limiting factor, then the runner must resort to running by feel.
It is not enough that heat and humidity interact with the pace-intensity relationship, it is also understood that different athletes react to heat differently—that is, some athletes are better at dissipating heat than are others (17). Such a finding complicates the additional use of heat-pace transformation charts (5).
Altitude. The influence that altitude has on training intensity has been implemented in the training of many elite athletes. Daniels (5) explains how “as you go up in altitude, the atmospheric pressure gets lower, and the lower the atmospheric pressure, the lower the pressure of oxygen” (p. 57). The reduced oxygen effects VO2max, making workouts at target pace more aerobically stressful. Incidentally, Daniels once again admits that subjective feelings of effort must be used to monitor these workouts at altitude (p. 58). In any event, readers are provided with a chart that maps out sea-level paces with their adjusted paces at various altitude (Figure 3.3). The chart suggests that altitude paces be adjusted as a percentage of the distance run: a one-hour race pace at 1,500 m. (5,000 ft.) should be increased by a magnitude of 5%.
Wind. Like heat and altitude, it is also understood that headwinds and tailwinds interact with the pace-intensity relationship. The presence (or absence) of wind has consequences for the athlete: the presence of a head- or cross-wind can aid in cooling the body, whereas a light tailwind can actually inhibit the dissipation of heat. A strong headwind will decrease forward velocity whereas a tailwind will increase this, per the laws of mechanical physics. Simple, yes, but the presence of wind certainly interferes with the anticipated relationship between pace and intensity. However, provided one is aware of the force of the wind (assuming it remains constant) and the direction of the wind (assuming that this, too, remains constant), there is a table that can aid the athlete in accounting for the presence of wind (Table 8.3).
After looking at heat, altitude, and wind, it is understood that the relationship between pace and intensity is subject to the interaction effects of many different variables. This is by no means a comprehensive list! Consider the effects of elevation change (uphills and downhills), and terrain (pavement, hard and loose dirt, and sand), not to mention a whole variety of additional, non-environmental factors such as busyness of schedule, amount of sleep and rest, stress-levels, nutrition, and so on.
Higdon (10) summarizes the great variability of these factors nicely when he writes: One variable is weather. And “whether.” Whether it is cold or hot, whether it is windy or rainy, can effect how fast or far you run during any given workout. The number of miles you have run does not necessarily reflect the quality of your training” (p. 152).
Measuring effort levels by pace assumes that all other variables remain the same. If any of these variables are less than ideal, it is expected that the pace-intensity relationship must undergo a mathematical transformation. Let’s consider a hypothetical scenario: a five kilometer race with a 15 km/h W/NW wind; run at an altitude of 1,500 meters; in a temperature of 32 degrees Celsius. My target pace is 3:10/km. I must add five seconds per kilometer for elevation; add eight seconds for heat; now subtract five seconds when running with the wind, and add five seconds when running against the wind. With only three additional variables that interact with the pace-intensity relationship, we quickly find that this procedure is needlessly complicated.
The following section examines the privileged position that VO2 has with pace-based training methods. It is argued that VO2 is just one of many physiological markers of intensity, and that there is some ambiguity regarding their interrelationship.
Argument Two: One Marker of Intensity is not “as Good as” or “Better than” the Rest
Assume for a moment that pace does correspond perfectly with VO2 levels. This, of course, is to maintain that all other intervening factors are of no consequence. One must still assume that VO2 is the best indicator of intensity, instead of blood-lactate levels, heart rate, or another physiological measurement (like core body-temperature). While there does seem to be a relationship between the varieties of intensity measures, the exact relationship between them is unclear. It has already been demonstrated how the monitoring of only one of the physiological measurements of intensity would necessarily leave out important factors. Thus, it is difficult to determine upon which measure of intensity to rely. As Seiler and Kjerland (18) explained above, “these numerous intensity zones suggest a degree of physiological specificity that is not really present.”
While thresholds have been correlated with physiological markers—e.g. increased heart rate, accumulation of lactic acid in the blood, increased oxygen intake—there is some ambiguity as to whether these physiological mechanisms are directly responsible for the onset of fatigue. “[I]ntensity zone boundaries” Seiler and Kjerland (18) explain, “are not clearly anchored in underlying physiological events” (pp. 49-50). Consider the case of blood-lactate levels: as blood-lactate levels increase from 2.0 mM to a maximum 4.0 mM, there is also marked increase in VO2. However, this positive relationship between blood-lactate and ventilation interacts with environmental factors—values from laboratory tests on a treadmill differ from those gathered during outdoor tests on a track (20). Just like the relationship between pace and VO2, there are additional variables that interact with the relationship between blood-lactate levels and VO2. To be sure, blood-lactate and ventilation have a positive correlational relationship, but the variability that the tests have demonstrated are enough to draw into question the primary importance of either (upon which it may be understood that the other is contingent).
Oxygen consumption, lactate accumulation, and HR each increase as the intensity of exercise increases. Moreover, each physiological marker has been used to design schedules and to monitor training in long distance runners. Each of these reference points provides reliable, robust, and reasonably practical data that is helpful in understanding training in an objective manner. But monitoring ventilation, blood-lactate levels, and heart-rate is not always practical. While the relationship between velocity and VO2 provides a seemingly simple external indicator for exercise intensity, this either ignores too many variables or requires that the athlete compute far too many statistics for it to be of any meaningful help. Finally, even the exercise scientists have conceded that the athlete ought to consult the non-operationalized “felt-sense” in unusual running conditions.
Effort expenditure while running is complicated in that it comprises many factors. It can be understood in part through a physiological standpoint by monitoring the level of intensity as indicated by heart rate, oxygen consumption, or blood-lactate levels. The exact relationship between these indications of intensity is somewhat unclear. Effort can also be influenced by psychological factors—e.g. through social context and desire. Finally, there is also evidence of an interaction between physiological and psychological factors.
The popularity of pace-based training has been examined in light of the complicated interrelationships between physiological and psychological factors that mediate effort. It has been argued that a pace-based approach is supported by two problematic assumptions. The first is the relationship between velocity and intensity. While one finds a positive correlation here, the two are not synonymous—that is, effort level should not be reduced to a particular velocity or pace. Too many additional variables interact with the velocity – effort relationship. The second assumption is that any measure of physiological intensity is as good as the rest. By measuring effort levels through a single physiological marker (e.g. VO2), one necessarily misses out on the expression of effort through additional physiological markers—ones that VO2 might miss. While this is a less conspicuous problem, it simplifies the understanding of effort in a way that ignores its complexity.
APPLICATIONS IN SPORT
This article has been written with runners of all ability levels in mind, and for the coaches that train them. While it may seem a bit unsettling to train without the immediate external feedback that velocity-measures provide, it has been argued that this ignores a more carefully tuned instrument: an athlete’s subjective awareness of exertion. Monitoring velocity (that is, pace) only provides a single factor of exertion—and this factor is twice removed from the actual experience of effort involved. Moreover, it ignores the other important factors that combine to determine exertion: factors like weather, temperature, and altitude. Running by feel coordinates all of these factors into a single experience: perceived exertion. So ditch the watch and start training by feel.
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