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ResourcesGuides1RM CalculatorTDEE CalculatorMacro Calculator (Lifters & Runners)ACWR CalculatorAbout

Training library

Guides for lifters who run.

Plain-English explanations of the training science behind Mass in Motion: how to manage lifting and running load together, read your recovery, dial in pace, and set the numbers that drive your program. No fluff, no AI-written filler.

Hybrid

Hybrid Athlete Training

Build strength and running fitness at the same time without either one wrecking the other: the interference effect, session order, and weekly structure.

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Hybrid

Concurrent Training

Can you build muscle and run at the same time? What the interference effect really means and how to program both so each keeps progressing.

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Hybrid

Lifting & Running the Same Day

Which to do first, how many hours to leave between them, and why order and spacing change your results when you train both in one day.

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Strength

RPE & RIR

Autoregulate your lifting to how strong you actually are on the day: how the scales work, how they relate to percentages, and why it beats fixed numbers.

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Strength

Conjugate-Style Training

Rotate max-effort, dynamic-effort, and repetition work to get stronger without grinding limit sets every week, and why it suits athletes who run.

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Running

Running Pace Zones

Why easy runs should make up most of your weekly volume, how race-predicted pace targets are set, and what each training zone is actually for.

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Running

Marathon Training for Lifters

Build the miles without surrendering your strength: mileage ramps, protecting your lifting, and coordinating the taper.

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Recovery

HRV & Recovery Score

What heart-rate variability actually measures, why a daily readiness score is useful, and how recovery-aware programming adjusts to how you slept and recovered.

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Recovery

ACWR & Managing Load

The acute-to-chronic workload ratio explains why athletes get hurt when they spike volume too fast, and how to ramp safely across lifting and running.

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Recovery

How to Use the ACWR Calculator

A step-by-step walkthrough of the free ACWR calculator: what to enter for each day, how the effort-times-minutes load works, and how to read your ratio.

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Recovery

Deload Weeks

When to take a planned easy week, what to actually reduce, and how backing off at the right time lets your fitness finally surface.

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Recovery

Sleep Hygiene & Circadian Rhythm

Science-backed strategies to optimize sleep quality: circadian light timing, ideal bedroom temperature, pre-bed heat therapy, nutritional timing, and sleep-supporting supplements.

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Tools

1RM Calculator

Estimate your one-rep max from any set with the Epley formula, then read the training percentages behind max-effort, hypertrophy, and speed work.

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Tools

TDEE Calculator

Find your Total Daily Energy Expenditure and a daily calorie target that supports lifting and running, with a plain-language guide to what it all means.

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Tools

Macro Calculator for Lifters and Runners

Turn your calorie target into protein, carbohydrate, and fat targets with a training focus for hybrid athletes: strength, endurance, hybrid, fat loss, lean gain, or high-mileage fueling.

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Tools

ACWR Calculator

Calculate your acute-to-chronic workload ratio (ACWR) from your last 7 days of training to prevent overtraining and manage injury risk.

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Basics

What Is Mass in Motion?

The short version of what the app is, who it is for, and how lifting and running live in one adaptive system.

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Basics

How It Works

How the app builds and adjusts your plan: the principles and guardrails behind it, and why it is algorithm-driven rather than AI-generated.

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One app for the lift and the run

Recovery-aware programming that plans your lifting and running together. Join the update list for launch news and founder pricing.

Want to beta test the app? The update list is for news. Beta access is a separate application.

Apply for the beta →