Creatine: The Most Boring, Best-Studied Supplement in the Gym
No proprietary blend, no marketing gloss — just one of the most researched compounds in sports science. Here's what creatine actually does, and doesn't.
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The Heartstream Blog
Heart-rate training, hybrid athleticism, group-training culture, and the science of effort — from the team building live HR for gyms.
The 80/20 Rule: Why Most of Your Training Should Feel Easy
Elite endurance athletes spend roughly 80% of their training time easy and 20% hard. Here's the science behind polarized training, and how it shows up on the board.
Know Your Zones: Zone 5 Is Red, Brief, and Non-Negotiable
Zone 5 Peak is the shortest, most explosive heart-rate zone — and the easiest to misuse. Here's what it's actually for and why it belongs in minutes, not miles.
Know Your Zones: Zone 1 Is the Blue Tile Everyone Skips
Zone 1 Recovery looks like doing nothing. It's the zone that decides whether the hard work you did yesterday actually becomes fitness.
Know Your Zones: Zone 4 Is Where Orange Starts Talking Back
Zone 4 Threshold is the hardest pace you can hold and still call sustainable. Here's why the orange tile is the single best predictor of race-day performance.
Know Your Zones: Zone 3 Is the Yellow You Have to Earn
Zone 3 Tempo is where comfort ends and real training begins. Here's why the yellow tile is the most misunderstood — and most powerful — zone in the building.
Know Your Zones: Why Zone 2 Is the Base Every Athlete Is Built On
Zone 2 is the unglamorous green tile that builds your aerobic engine. Here's what it is, why it matters, and how to actually find it on the screen.