Heart Rate Reserve (HRR)

By the Watta Team · Updated

Heart Rate Reserve (HRR): Heart rate reserve is the difference between maximum heart rate and resting heart rate, used in the Karvonen formula to calculate personalised training zones for rowing.

What is Heart Rate Reserve (HRR)?

Heart rate reserve (HRR) = maximum heart rate minus resting heart rate. For example, if your max HR is 190 and resting HR is 50, your HRR is 140 bpm. HRR is used in the Karvonen formula to calculate individualised training zones: Target HR = resting HR + (intensity % × HRR). This method is more accurate than simple percentage-of-max-HR calculations because it accounts for individual cardiac fitness — a person with a low resting HR has a larger functional range. HRR-based zones are the standard in rowing training prescription and are used by most structured rowing programmes.

How Watta Uses Heart Rate Reserve (HRR)

Watta uses the Karvonen method (HRR-based) to calculate heart rate zones and the Cardiac Load component of the Effort Score. When you provide your max HR and resting HR, the algorithm uses HRR to determine intensity zones and apply non-linear scaling to the cardiac load calculation (40% of total score).

Further Reading

Frequently Asked Questions

How do I find my heart rate reserve?
Measure your resting heart rate first thing in the morning (average over 3 days). Then determine your max HR through a graded exercise test or hard 2K effort. HRR = max HR - resting HR.
Why is HRR better than percentage of max HR?
HRR accounts for individual fitness. Two people with the same max HR of 190 but different resting HRs (50 vs 70) have different functional ranges. The Karvonen method using HRR produces more personalised and accurate training zones.
What is a typical HRR for rowers?
Recreational rowers: 110-130 bpm. Well-trained rowers: 130-150 bpm. Elite endurance athletes: 140-160+ bpm. A higher HRR generally indicates better cardiovascular fitness.

Related Content

Heart Rate Zones (Rowing)Heart rate zones in rowing are five intensity bands based on resting and max heart rate, used to target different training adaptations.Aerobic ThresholdThe aerobic threshold is the exercise intensity where lactate begins to rise above resting levels, typically around 55-70% of VO2 max in trained rowers.Lactate ThresholdLactate threshold in rowing is the exercise intensity at which blood lactate begins to accumulate exponentially (approximately 4 mmol/L), representing the upper boundary of sustainable aerobic effort.Karvonen FormulaThe Karvonen formula calculates personalised heart rate training zones using heart rate reserve: Target HR = Resting HR + (Intensity % × (Max HR - Resting HR)).Resting Heart RateResting heart rate is the number of heart beats per minute while fully at rest, typically 60-80 bpm for adults and 40-55 bpm for well-trained endurance athletes.Heart Rate Training ZonesHeart rate training zones divide your heart rate range into intensity bands (typically 5 zones), each targeting different energy systems and physiological adaptations for rowing training.Maximum Heart RateMaximum heart rate (HRmax) is the highest number of beats per minute your heart can achieve during all-out exercise, used as the ceiling for calculating training zones.HR Zone CalculatorEffort Score CalculatorHeart Rate Training for RowingFor Competitive Rowers
Free on iPhone

Every erg counts.

Photograph your erg screen after the piece and Watta logs it for you.

Download on the App Store

iPhone, iOS 15.1 or later · no subscription · Android beta

See everything Watta does