About
A little bit of context on this project.
What this is
Online Human Exercise is a free collection of browser-based exercises for reaction time, eye coordination and focus, memory, mental math, and guided breathing, plus eight free fitness calculators — from TDEE and macros to heart rate zones and running pace — and science articles explaining the research behind each exercise and tool. Each one is a self-contained page you can open and use immediately — no accounts, no installs, no downloads. Open an exercise, adjust the controls to your level, and start.
Why it exists
Simple, focused tools are often more useful than bloated apps. These exercises are built to do one thing well: give your eyes, reflexes, or memory something structured to work on, with just enough controls (speed, size, rounds, session length) to tune the difficulty yourself — and your best scores and progress saved on your own device so you can see yourself improve.
The exercises
- Visual Reaction Time Test: wait for the screen to turn green, then click as fast as you can.
- Audio Reaction Time Test: react to a beep instead of a color change.
- DVD Bounce — Eye Training: follow a single bouncing ball and read the number that flashes inside it.
- Random Pops — Eye Training: track colored targets that appear at random positions across the screen.
- Schulte Table: find the numbers in a shuffled grid in order, as fast as you can, to train focus and peripheral vision.
- Sequence Memory Test: watch a growing sequence of tiles light up, then tap them back in the same order.
- Mental Math Practice: timed addition, subtraction, multiplication, and division drills with 1- to 7-digit numbers in any combination, or a no-repeat progression through every two-digit problem.
- Box Breathing & 4-7-8 Breathing: follow an animated guide through two popular slow-breathing techniques.
The tools
- TDEE Calculator: estimate daily calorie needs for maintenance, weight loss, or weight gain.
- Macro Calculator: split a daily calorie target into grams of protein, carbs, and fat.
- Weight Loss Timeline: estimate a goal date from a weekly rate, or the rate a target date needs.
- BMI Calculator: calculate Body Mass Index and see its category.
- Body Fat Calculator: estimate body fat percentage with the U.S. Navy tape-measure method.
- Heart Rate Zone Calculator: find your five training zones with the Karvonen method.
- Running Pace Calculator: convert between pace, finish time, and distance, with splits.
- Barbell Plate Calculator: work out which plates to load on each side of the bar.
The articles
Each exercise and fitness calculator has a companion article covering the theory behind it, a brief history, and what published research says about its benefits and limits, with references.
- The Science of Reaction Time: Why Milliseconds Matter
- Smooth Pursuit: How Your Eyes Follow a Moving Target
- Peripheral Vision and Visual Attention: Seeing More Than You Look At
- The Schulte Table: The Science of Visual Search and Focus
- Working Memory: How Much Can Your Mind Hold at Once?
- Mental Math: What Happens in Your Brain When You Calculate
- Box Breathing and 4-7-8 Breathing: The Science of Slow Breathing
- Heart Rate Training: The Science of Zones and the Karvonen Formula
- Pacing Strategy: The Science of Running Your Best Race
- Protein, Carbs, and Fat: The Science of Macronutrients
- Measuring Body Fat: What the Tape, the Scale, and the Scanner Tell You
- Why Weight Loss Slows Down: The 3,500-Calorie Rule and Your Metabolism
- Progressive Overload: The Science of Getting Stronger
Not medical advice
This project is built for casual, general wellness use — not as a medical or therapeutic device. See the Disclaimer for details.