What is the upper bound of the Very Hard target heart rate zone?

What is the upper bound of the Very Hard target heart rate zone?

• A. 100%
• B. 99%
• C. 90%
• D. 95%

Answer: (B)

Very Hard is meant to push you near your limit, but not at the exact maximum you could theoretically reach. In practice, the upper bound is set just below that maximum to reflect what you can sustain briefly and to account for variability in max heart rate estimates and measurement accuracy. Using 99% as the ceiling gives a near-max effort that’s still practical and safe for training. A 100% upper bound would imply holding your true max, which isn’t realistic for sustained work; values around 90% or 95% are too low to characterize Very Hard, which is why 99% is the best match for the upper limit.

Very Hard is meant to push you near your limit, but not at the exact maximum you could theoretically reach. In practice, the upper bound is set just below that maximum to reflect what you can sustain briefly and to account for variability in max heart rate estimates and measurement accuracy. Using 99% as the ceiling gives a near-max effort that’s still practical and safe for training. A 100% upper bound would imply holding your true max, which isn’t realistic for sustained work; values around 90% or 95% are too low to characterize Very Hard, which is why 99% is the best match for the upper limit.