What is more important on race day?
- The pace displayed on your watch, or the actual physiological strain experienced by your body?
- Why can the exact same pace feel completely controlled on one day and lead to premature fatigue on another?
- When should we stick to our planned race pace, and when should we adjust it?
Understanding these questions is a fundamental component of proper effort management and optimal race performance.
THE SCIENCE
During both training and competition, most runners use pace per kilometer as their primary indicator of exercise intensity. However, one thing must be made clear:
The body does not “see” the pace displayed on a sports watch.
What it actually perceives is the physiological and metabolic cost required to sustain that pace.
In other words, two training sessions performed at exactly the same pace may place completely different demands on the body.
Factors such as:
- temperature
- humidity
- wind
- uphill and downhill gradients
- recovery status
- accumulated fatigue
can significantly alter the physiological cost of exercise.
As a result, attempting to maintain a predetermined pace may lead to a disproportionate increase in:
- heart rate
- energy expenditure
- thermal strain
- perceived fatigue
For this reason, modern training approaches place particular emphasis on managing intensity, rather than rigidly adhering to a specific pace.
Heart rate, perceived exertion, and an understanding of individual physiological limits often provide more reliable guidance than pace alone.
According to the scientific literature, an effective pacing strategy is one of the most important determinants of endurance performance.
Pacing strategies in marathons: A systematic review
THE APPLICATION
Why is race pace not always the same?
In practice, the goal is not to chase a specific pace. What we should aim for is maintaining the desired exercise intensity.
A runner who plans to race at, for example, 5:00/km does not necessarily need to run every kilometer at exactly that pace, regardless of the conditions.
Temperature
An increase in temperature leads to greater cardiovascular strain.
At the exact same pace:
- heart rate increases
- thermal stress becomes greater
- fatigue develops earlier
Under such conditions, a small adjustment in pace is often the most appropriate training and racing decision.
Uphills and Downhills
Effort does not remain constant when terrain changes.
Trying to maintain the same pace uphill may result in excessive physiological strain and premature fatigue.
Conversely, adjusting pace while aiming to maintain a similar level of intensity allows for more effective management of the overall effort.
Heart Rate
Heart rate is not an absolute measure of performance, but it provides valuable information regarding physiological stress.
A gradual increase in heart rate during prolonged exercise (cardiovascular drift) is a common phenomenon in both training and racing.
Recognizing this response helps athletes make more informed adjustments to exercise intensity.
Perceived Exertion
Experienced runners gradually learn to integrate:
- pace
- heart rate
- perceived effort
and make decisions based on the combination of these factors rather than relying on a single metric.
KEY PRINCIPLES OF APPLICATION
Race pace should:
- be adjusted according to the conditions of the day
- take temperature and course profile into account
- reflect the actual physiological stress of the effort
- support overall performance rather than a single split time
CRITICAL POINT
Rigidly adhering to a predetermined pace when conditions do not allow it often leads to:
- excessive physiological strain
- uncontrolled increases in heart rate
- loss of the intended training stimulus
- significant performance decline during the later stages of the effort
COACHING PRINCIPLE
Η επιτυχία συνδέεται από την ικανότητα προσαρμογής της έντασης στις πραγματικές απαιτήσεις της προσπάθειας και δεν προκύπτει από την απόλυτη προσήλωση σε έναν προκαθορισμένο ρυθμό.
Human running performance from real-world big data
Dimitrios Theodorakakos
Sports Director @sportsexcellence
Sports Excellence Team