Zone 4 (Supra-threshold)

Anaerobic (Lactate) Threshold or Cruise Intervals – This zone will build metabolic fitness (i.e., a higher lactate threshold) and enhances one’s ability to sustain hard work & a faster pace or higher power output. In Zone 4, significant levels of fatigue, as represented by increases in lactate, are produced while not at a rate that overwhelms your energy systems. Zone 4 sessions should always be separated by a recovery period of 2-3 days to assure optimal recovery and then compensation from this training overload. Ultimately, both athletes and fitness enthusiasts (including weight watchers) can benefit from appropriate Zone 4 training.

A rating of perceived exertion (RPE) between 4 and 7

92-98% of your maximum heart rate (MHR) or

5-10 beats above your LT or 100-105% of your heart rate at Anaerobic threshold (AT)

Forceful breathing and an all out effort to sustain pace up to 1 hour.  

Here are some example graphical depictions of zone 4 interval session:

Step-up to zone 4 = Just starting? Follow this interval step up pattern to adjust to the new zone 4 intensity.  An early program might suggest you build to a the peak zone 4 heart rate for 1 minute then drop the workload to starting level for two-five minutes, check your heart rate during the recovery waiting until HR returns to zone 1 or 2 before starting next climb.

Higher fit = Long intervals. Adjust intensity of exercise to maintain work-rate (pace or power) in Zone 4 for prescribed interval duration (2-20 minutes). Objective here is to increase metabolic fitness (i.e., lactate or anaerobic threshold increase). Benefits include higher maximal steady state and increased sustainable pace or work level. For a smart and effective progression add 1-2 minutes to each up-interval every week (see sample progression).

Higher fit = Fartlek comes from the Swedish word meaning 'speed play'. This form of training involves alternating fast and slow speeds during a session. Most references suggest the use of undulatiing terrain and a lot of variety as the key aspects of this type of Fartlek training. The actual amount of fast and slow speeds (high & low intensity) is left up to the exerciser and how they feel.

Sample Zone 4 training sessions:

Running (these can be modified for use on the stepper and elliptical machines)

• Long repeats 1600 meters (1 mile) x 3 in Zone 4 with recovery for the same time it takes to do repeats.
• Tempo intervals (race pace)
• 10K = 400-1200 meter repeats with equal or 1 ½ time in recovery between repeats
• ½ marathon = 400-2000 meters with equal time in recovery
• Marathon = 800-3200 meters with equal time in recovery
• Steady state intervals (10-20 min.) on road or with long steady climbs or tempo (race pace) workouts at 10K pace.
• Fartlek training for 20 minutes (2-4 intervals).
• Crisscross threshold training. Choose a flat course. Warm-up and then run 20 minutes in zone 4.
• Crisscross from low zone 3 to high Zone 4 every 1-2 minutes.
• Step-ups. Warm-up, building to Zone 3 heart rate. Hold for 15 minutes. Then step-up to Zone 4-5a heart rate for 5 minutes. Relaxed form. Cool down.** (Note 5a = first 5 beats into Zone 5).

Cycling

• Cruise intervals on road or trainer. Do 4-5 sets of 5-10 minutes in Zone 4 with 2 minute recoveries. Smooth pedaling, 80-90 rpm’s.
• Threshold or Tempo ride for 25-60 minutes steady in zone 4. Non-stop. Flat course on your time trial set-up. Smooth pedaling – 85-100 rpm’s.
• Crisscross threshold training. Choose a flat course. Warm-up and then ride 20 minutes in zone 4.
• Crisscross from low zone 3 to high zone 4 every 1-2 minutes. 85-100 rpm’s.

FINDING YOUR ZONES
If you are unable to get tested in the lab you can estimate your zones by going online to…

Lactate Threshold Tester (estimator) at http://www.fitstop-lab.com/tools/intensityindex.htm or 
I can help you set-up your zones online at http://www.fitstop-lab.com/CMSpro.htm