One of the first things you need to do to begin training is determine your training zones. This handy calculator is the perfect place to start. But first, a very special thanks to Uphill Athlete, Simon, for creating this very cool heart rate calculator tool.

Note that we after many decades of training and coaching mountain athletes using heart rate zones as a guide we have settled on this very simple 4-zone system.

Defining the Heart Rate Zones

By anchoring this system to two important metabolic markers (AeT and AnT/LT), this simple 4-zone system does a good job of personalizing intensities to your unique metabolic response.

Zone 1 

Heart Rate: AeT-20% to AeT-10%
Rate of Perceived Exertion (RPE): 1-2,  very easy to easy
Training Effect/Purpose: Aerobic conditioning
Metabolism: Aerobic-fat
Muscle Fiber Recruitment: ST
Training Method: Continuous 30 min to several hours

Zone 2

Heart Rate: AeT-10% to AeT
Rate of Perceived Exertion (RPE): 5-6, moderate for those with high AeT, easy for those with low AeT
Training Effect/Purpose: Aerobic capacity, economy
Metabolism: Aerobic-fat dominates, maximum fat utilization
Muscle Fiber Recruitment: Most ST
Training Method: Continuous 90 min-several hours

Zone 3

Heart Rate: AeT to Lactate Threshold
Rate of Perceived Exertion (RPE): 7-8 Medium to comfortably hard 
Training Effect/Purpose: Aerobic capacity, anaerobic capacity, lactate shuttle, economy
Metabolism: Glycolytic/anaerobic begins to dominate
Muscle Fiber Recruitment: All ST + some FT
Training Method: Interval 10–20 min, continuous to 60 min

Zone 4

Heart Rate: Lactate Threshold to LT to maxHR
Rate of Perceived Exertion (RPE): 9-10 Hard, max sustainable
Training Effect/Purpose: Maximal aerobic power, strength/speed endurance, economy, technique
Metabolism: Both aerobic and anaerobic capacities maxed out
Muscle Fiber Recruitment: All ST + most FT
Training Method: Interval 30 sec–8 min