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The Aerobic Threshold: HYROX's Most Underrated Performance Metric?
The Aerobic Threshold: HYROX's Most Underrated Performance Metric?
Why the first lactate threshold (LT1/VT1) is the most overlooked performance metric in HYROX, and how to find yours.
Why the first lactate threshold (LT1/VT1) is the most overlooked performance metric in HYROX, and how to find yours.
by
Dr. Dan Plews
6
min read
In endurance and hybrid sport like HYROX, we spend a lot of time talking about thresholds. Physiologically, threshold is defined as the transition from steady-state to non-steady-state physiological responses to exercise. Above the second threshold — commonly referred to as the anaerobic threshold — oxygen consumption, lactate, and muscle/blood acidity cannot stabilise, and fatigue inevitably develops.
While knowledge of this second threshold is significant for HYROX athletes, we argue that knowledge of the first physiological threshold — often called the aerobic threshold or more accurately the lactate threshold (LT1, VT1) — is of equal significance.
WHAT IS IT?
The first threshold defines the boundary between moderate and heavy exercise-intensity domains. Below this threshold, blood lactate concentrations are stable and essentially equal to baseline. Above it, lactate may stabilise but at elevated concentrations. Exercise below the lactate threshold is conversational — easy enough to hold a conversation without undue effort.
WHY IS KNOWLEDGE OF THIS THRESHOLD IMPORTANT?
The lactate threshold defines the upper limit for moderate-intensity training sessions designed to produce minimal physiological stress and allow rapid recovery. That is why many higher-performing athletes follow a pyramidal or polarised training intensity distribution, with upwards of 75–80% of total training time at intensities below the lactate threshold. The principle: easy training easy, and hard training hard.
HOW DO WE IDENTIFY IT?
Ideally, lactate threshold is identified through laboratory testing. A practical alternative is the Talk Test, where lactate threshold is identified as the workload at which an athlete can no longer comfortably talk. Research shows no significant systematic differences between lactate threshold pace or heart rate estimates using physiological data versus the talk test.
HAVE A GO
Use a graded protocol with conversation checks. Use the running pace of the last stage you could read comfortably as your lactate threshold power estimate, and take the heart rate from 2:00–2:30 of that stage as your lactate threshold heart rate estimate.
ENDUROX CALCULATOR
Establishing training zones is critical. You can estimate your Level 2 training zone (top of VT1/aerobic threshold) as a percentage of your 5 km time using the ENDUROX running zones calculator.
In endurance and hybrid sport like HYROX, we spend a lot of time talking about thresholds. Physiologically, threshold is defined as the transition from steady-state to non-steady-state physiological responses to exercise. Above the second threshold — commonly referred to as the anaerobic threshold — oxygen consumption, lactate, and muscle/blood acidity cannot stabilise, and fatigue inevitably develops.
While knowledge of this second threshold is significant for HYROX athletes, we argue that knowledge of the first physiological threshold — often called the aerobic threshold or more accurately the lactate threshold (LT1, VT1) — is of equal significance.
WHAT IS IT?
The first threshold defines the boundary between moderate and heavy exercise-intensity domains. Below this threshold, blood lactate concentrations are stable and essentially equal to baseline. Above it, lactate may stabilise but at elevated concentrations. Exercise below the lactate threshold is conversational — easy enough to hold a conversation without undue effort.
WHY IS KNOWLEDGE OF THIS THRESHOLD IMPORTANT?
The lactate threshold defines the upper limit for moderate-intensity training sessions designed to produce minimal physiological stress and allow rapid recovery. That is why many higher-performing athletes follow a pyramidal or polarised training intensity distribution, with upwards of 75–80% of total training time at intensities below the lactate threshold. The principle: easy training easy, and hard training hard.
HOW DO WE IDENTIFY IT?
Ideally, lactate threshold is identified through laboratory testing. A practical alternative is the Talk Test, where lactate threshold is identified as the workload at which an athlete can no longer comfortably talk. Research shows no significant systematic differences between lactate threshold pace or heart rate estimates using physiological data versus the talk test.
HAVE A GO
Use a graded protocol with conversation checks. Use the running pace of the last stage you could read comfortably as your lactate threshold power estimate, and take the heart rate from 2:00–2:30 of that stage as your lactate threshold heart rate estimate.
ENDUROX CALCULATOR
Establishing training zones is critical. You can estimate your Level 2 training zone (top of VT1/aerobic threshold) as a percentage of your 5 km time using the ENDUROX running zones calculator.
