Tempo Runs: Understanding Your Target Heart Rate, Calculation, and Training Integration

What should my heart rate be for a tempo run?

For a tempo run, your heart rate should typically fall within 80-90% of your maximum heart rate (MHR) or 85-92% of your heart rate reserve (HRR), corresponding to your lactate threshold zone. This pace should feel "comfortably hard," allowing for short, broken sentences but not full conversation.

Understanding the Tempo Run

A tempo run, also known as a lactate threshold run, is a cornerstone workout for endurance athletes, particularly runners. Its primary purpose is to improve your body's ability to clear and buffer lactate, allowing you to sustain a faster pace for longer periods without accumulating excessive fatigue. Unlike easy recovery runs or high-intensity interval training, tempo runs are performed at a sustained, challenging effort that pushes your physiological limits without leading to immediate exhaustion.

Physiological Benefits:

• Increased Lactate Threshold: Your body becomes more efficient at utilizing lactate for fuel and clearing it from the bloodstream, delaying the onset of fatigue.
• Improved Endurance: Enhances your stamina and ability to maintain higher speeds over extended durations.
• Enhanced Mental Toughness: Develops the mental fortitude required to sustain uncomfortable efforts.

The Science Behind Tempo Run Heart Rate

The target heart rate for a tempo run is directly linked to your lactate threshold (LT), sometimes referred to as your anaerobic threshold (AT). This is the point at which lactate begins to accumulate in the blood at a rate faster than it can be cleared. Beyond this point, fatigue accelerates rapidly.

Training at or just below your lactate threshold forces your body to adapt and become more efficient at:

• Producing energy aerobically at higher intensities.
• Transporting and utilizing oxygen more effectively.
• Buffering the acidic byproducts of anaerobic metabolism.

By training in this zone, you effectively "raise" your lactate threshold, meaning you can run faster before hitting that point of rapid fatigue.

Determining Your Tempo Run Heart Rate Zone

While precise laboratory testing can pinpoint your exact lactate threshold, several practical methods can help you estimate your tempo run heart rate zone.

• General Heart Rate Percentage:
  • 80-90% of Maximum Heart Rate (MHR): This is a commonly cited range.
  • 85-92% of Heart Rate Reserve (HRR): This method, using the Karvonen formula, is generally considered more accurate as it accounts for your resting heart rate.
• Perceived Exertion (RPE): On a scale of 1-10, a tempo run should feel like a 7-8 out of 10. It's a "comfortably hard" effort that you could sustain for 20-60 minutes. You should feel challenged but not completely breathless.
• The Talk Test: During a tempo run, you should be able to speak in short, broken sentences, but not carry on a full conversation. If you can chat freely, you're not going hard enough. If you can't speak more than a word or two, you're likely going too hard.
• Field Tests:
  • 30-Minute Time Trial: Run as hard as you can for 30 minutes. Your average heart rate during the last 20 minutes of this effort can be a good approximation of your lactate threshold heart rate.
  • Conconi Test: A progressive running test where heart rate is monitored against increasing speed to identify the point where the heart rate curve deflects.

Calculating Your Target Heart Rate

To use heart rate percentages effectively, you'll need to know your estimated maximum heart rate (MHR) and, for the Karvonen formula, your resting heart rate (RHR).

1. Estimating Maximum Heart Rate (MHR):

• Simple Formula (Rough Estimate): 220 - your age. (e.g., for a 30-year-old: 220 - 30 = 190 bpm). This is a general estimate and can vary significantly among individuals.
• Tanaka, Monahan, & Seals Formula (More Accurate for Adults): 208 - (0.7 x age). (e.g., for a 30-year-old: 208 - (0.7 * 30) = 208 - 21 = 187 bpm).

2. Determining Your Resting Heart Rate (RHR):

• Measure your pulse for one minute immediately upon waking, before getting out of bed. Repeat for a few days and take the average.

3. Using the Karvonen Formula (Heart Rate Reserve - HRR): The Karvonen formula is generally preferred because it personalizes the training zones by taking your resting heart rate into account.

• Step 1: Calculate Heart Rate Reserve (HRR): HRR = MHR - RHR
• Step 2: Calculate Target Heart Rate (THR): THR = (HRR x % intensity) + RHR

Example for a 30-year-old with MHR of 187 bpm and RHR of 60 bpm, targeting 88% HRR:

• HRR = 187 - 60 = 127 bpm
• THR = (127 x 0.88) + 60 = 111.76 + 60 = 171.76 bpm (approximately 172 bpm)

So, for this individual, a tempo run heart rate would be around 172 bpm. The range would be 85-92% of HRR, providing a specific target zone (e.g., 168-176 bpm).

Practical Application and Monitoring

• Use a Heart Rate Monitor: A chest strap or wrist-based optical sensor provides real-time data, allowing you to stay within your target zone.
• Listen to Your Body (RPE): While heart rate monitors are valuable, don't ignore your perceived effort. On some days, due to fatigue, stress, or environmental factors, your heart rate might be higher or lower than usual for a given effort. Adjust accordingly.
• Adjust for Variables:
  • Temperature and Humidity: Hot and humid conditions can elevate heart rate for the same effort.
  • Altitude: Higher altitudes increase heart rate due to less oxygen.
  • Fatigue: Accumulated training stress or lack of sleep can lead to a higher heart rate for a given pace.
  • Hydration: Dehydration can increase heart rate.
• Progression: As your fitness improves, your heart rate at a given pace will decrease, or you'll be able to run faster at the same heart rate. Periodically re-evaluate your zones or perform new field tests.

Common Mistakes to Avoid

• Going Too Hard: Treating a tempo run like a race can lead to excessive fatigue, hinder recovery, and increase injury risk. You shouldn't be completely gassed at the end.
• Going Too Easy: If your heart rate is consistently too low, you won't stimulate the necessary physiological adaptations for lactate threshold improvement.
• Over-reliance on Formulas: Formulas provide estimates. Your individual physiology, current fitness level, and daily variables all play a role. Use them as a guide, not an absolute rule.
• Ignoring Body Signals: Pain, unusual fatigue, or a consistently elevated morning resting heart rate are signs to back off, regardless of what your training plan or heart rate monitor says.

Integrating Tempo Runs into Your Training

Tempo runs are a potent training stimulus and should be incorporated thoughtfully into your weekly schedule.

• Frequency: For most athletes, one tempo run per week is sufficient. Elite athletes might incorporate more, but this requires careful management of overall training load.
• Placement: Place tempo runs on a day when you are relatively fresh, not immediately after a hard workout or before a long run. Allow adequate recovery time (at least 24-48 hours) before your next hard session.
• Structure: A typical tempo run might include a warm-up (10-15 minutes easy), the tempo segment (20-40 minutes at target HR), and a cool-down (10-15 minutes easy).

When to Consult a Professional

If you're new to heart rate training, have underlying health conditions, or are unsure how to effectively integrate tempo runs into your training, consider consulting a certified running coach, exercise physiologist, or sports medicine physician. They can help you determine accurate heart rate zones, develop a personalized training plan, and ensure you're training safely and effectively.