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SATURDAY DEEP DIVE: THE EQUIPMENT
SATURDAY DEEP DIVE: THE EQUIPMENT
Sunday’s issue recommended a heart rate monitor. Today we cover the full monitoring landscape, how to calculate your personal zones, and the tools that make the 80/20 model sustainable over months and years.
SIM60 receives no commissions or affiliate compensation for any equipment referenced in this issue. All mentions are for illustration purposes only.
CALCULATING YOUR PERSONAL ZONES
Step 1 — Estimate your maximum heart rate:
The most accurate formula for adults over 40: 208 minus (0.7 times your age). For a 65-year-old: 208 – (0.7 × 65) = 208 – 45.5 = 162.5. Round to 163 bpm.
Step 2 — Calculate your zones from that maximum:
Zone 2: 60 to 70 percent. For a max of 163: 98 to 114 bpm.
Zone 4 (VO2 max intervals): 85 to 95 percent. For a max of 163: 139 to 155 bpm.
Zone 3 (the training middle to minimize): 70 to 85 percent. For a max of 163: 114 to 139 bpm.
These are estimates. The most accurate Zone 2 identification comes from metabolic testing (a VO2 max lab test at a sports medicine clinic), but the calculation above is adequate for practical purposes.
THE MONITORING STACK
Provides adequate heart rate accuracy for Zone 2 monitoring during steady-state walking and cycling. Accuracy decreases during high-intensity intervals and during activities with significant wrist movement. For Zone 2 work, a smartwatch is sufficient. Look for a device with a real-time heart rate display visible during exercise, not just post-session summaries.
The gold standard for heart rate accuracy. The electrical signal measured at the chest is more accurate than the optical signal from the wrist, particularly during interval work where heart rate changes rapidly. For anyone using the 4x4 protocol from Thursday’s issue, a chest strap is worth the additional investment. Knowing your actual heart rate during a 4-minute interval at 90 percent of maximum matters both for effectiveness and safety.
Tool 3: Training App with Zone Tracking (Garmin Connect, Polar Flow, Strava)
Zone-based training tracking allows you to see, after each session, how much time you actually spent in each zone. This data is often surprising — many sessions that feel like Zone 2 turn out to be Zone 3 when measured. Over weeks and months, the data reveals whether you are executing the 80/20 model or drifting toward the moderate middle. The free tiers of Garmin Connect and Strava cover this functionality.
For Zone 2 training specifically, these tools provide the most controllable intensity environment — eliminating weather, terrain, and traffic as variables. The rowing machine adds a full-body muscular demand that walking and cycling do not. Both are significant investments but last decades with minimal maintenance.
ISSUE #36 WEEK IN REVIEW
Sunday — The Zone 2 and VO2 max model: why the training middle is counterproductive, the 80/20 distribution, and the physiological basis for each zone. Introduced the Standing Doorway Chest Opener and the Loaded Farmer Walk with Nasal Breathing.
Tuesday — Three pre-cardio mobility drills: Doorway Chest Opener in three arm positions, Supine Rib Cage Lateral Expansion, brief Thoracic Extension over Foam Roller. The six-minute pre-cardio sequence.
Thursday — Zone 2 in three formats: walking protocol with nasal breathing test, cycling with RPM guidance, and the 4x4 interval structure for VO2 max. Zone heart rate calculations for a 65-year-old.
Today — The cardiovascular monitoring toolkit: wrist smartwatch, chest strap, zone-tracking apps, stationary equipment. Zone 2 and Zone 4 calculations from maximum heart rate.
Cardiovascular fitness is not about working hard. It is about working at the right intensity at the right time. Zone 2 is the foundation. High-intensity intervals are the stimulus. The moderate middle is where effort goes to produce minimal adaptation.
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LOOKING AHEAD
Issue #37 goes deep on hip mobility beyond hip flexors — specifically the hip capsule, the external rotators, and the range of motion that determines whether you squat, hinge, and move through daily life with freedom or restriction.
Still moving forward,
— The SIM60 Team
simsixty.com · Educational content only. Not medical advice.
