Best 4-Day Workout Split for Strength and Muscle
Upper/lower four days a week is the default for most people. A worked week, when to use PHUL, and why four-day PPL is usually the wrong shape.
Training, explained
Flux Workouts
Blog.
Practical guides and product updates about building a strength plan that keeps working when your time, equipment, performance and recovery change.
Training guide
Workout Plans
Splits, routines and schedules built for the time and equipment you actually have.
Workout Plans
Workout Plans
How to Run Hybrid Training in One Week
Lift and do timed cardio in the same week without turning Friday into two workouts. A three-day hybrid template, and how Flux Hybrid holds both in one routine.
Workout Plans
How to Build a Workout Around the Equipment You Actually Have
Build a balanced workout from the equipment you own or can access by matching movement roles instead of copying an exercise list.
Workout Plans
30, 45 or 60 Minutes: How Much Strength Training Can You Fit In?
Build a realistic 30-, 45- or 60-minute strength workout without rushing warm-ups, heavy sets or the exercises that matter most.
Workout Plans
Missed a Workout? Should You Skip It, Move It or Carry On?
Do not double up tomorrow. Move the session, carry on, or skip it — with a one-week example for full-body, upper/lower and PPL.
Workout Plans
Best Workout Split: Full Body vs Upper/Lower vs PPL
Full body for 2–3 days, upper/lower for 4, PPL for 5–6. A comparison table and a worked week to pick the split you can actually complete.
Workout Plans
Best 3-Day Workout Split for Strength and Muscle
Full-body A/B/C for most people training three days. Workouts, a calendar week, and when three-day PPL is the wrong choice.
Workout Plans
Best Workout Split for an Irregular Schedule
Use a rotating workout sequence when your week changes. Learn which splits tolerate missed days and how to keep training volume balanced without restarting.
Training guide
Progression
Practical ways to add load, reps and useful work without forcing progress that is not there.
Progression
What to Do When Your Lifts Stall
A stall is several hard sessions, not one bad day. Hold the load, check recovery, then change one thing — with a four-week squat example.
Progression
Double Progression vs Linear Progression: Which Should You Use?
Compare double progression with linear progression, see worked examples and choose a method that matches your experience and equipment.
Progression
RIR Explained: How Many Reps Should You Leave in Reserve?
Understand reps in reserve (RIR), choose a useful target for each exercise and improve your estimates without testing failure every set.
Progression
Progressive Overload: Should You Add Weight, Reps or Sets?
Add reps first, then the smallest weight jump. Add a set only after a real stall — with a four-week squat example.
Training guide
Recovery
How performance, sleep, fatigue and recovery context should influence the next session.
Recovery
Deload Week Guide: When You Need One and What to Change
Know when a deload is justified, how to reduce volume and effort, and when a rest week or programme change is the better answer.
Recovery
Low HRV Before a Workout: Train Hard, Ease Off or Ignore It?
Use a low HRV reading as context, not a command. Check the trend, measurement quality, symptoms and warm-up performance before adjusting training.
Recovery
Had a Bad Night’s Sleep? Here’s How to Adjust Your Workout
Decide whether to train normally, reduce the session or rest after poor sleep using performance, symptoms and workout risk—not guilt.
Training guide
Training Methods
Clear explanations of set roles, intensity techniques and programme design.
Training guide
Workout Apps
How workout planners, trackers and adaptive training systems differ in practice.
Workout Apps
Workout App That Uses Apple Health Sleep and HRV
Apple Watch data should change tomorrow’s session, not just sit in a ring. Flux can use sleep and HRV you choose to share — optional, on your terms.
Workout Apps
Fitbod Alternative That You Buy Once
Fitbod is a capable adaptive planner sold as a membership. Flux does the same job — a next session from your log — with a 14-day trial and one Lifetime Unlock.
Workout Apps
Best Workout App With No Subscription (2026)
Most gym apps rent you the plan by the month. Flux is free to download, a 14-day trial with no payment, then one Lifetime Unlock.
Workout Apps
Strong vs Hevy vs Flux: Which Workout App Should You Use?
Strong vs Hevy is a logger debate. Flux is the planner: 14-day trial, then one Lifetime Unlock — with free tiers, Watch apps and lifetime Pro spelled out.
Product archive
Flux Updates
Product releases and notes from the Flux Workouts team.
Flux Updates
Flux 8.8.1: Clearer targets, more room to progress
Optional Dynamic Targets, clearer set previews and better progression and recovery guidance. See what Flux 8.8.1 changes in your next workout.
Flux Updates
Flux 8.8.0: Your workout, all on one screen
Your whole workout, less screen switching. Log sets, adjust your session and check past performance alongside exercise settings.
Flux Updates
Flux 8.7.2: Clearer routines, honest Insights
See what each routine is for, how it runs, and which block you’re in — before you tap Select Routine.
Flux Updates
Flux 8.7.1: Hybrid training and a clearer workout review
Combine strength and cardio with Flux Hybrid, then review every set and see what's prescribed next.
Flux Updates
Flux 8.7.0: swap programme exercises, a new Workout Complete and smarter warm-ups
Swap exercises in Routine Library programmes, review each workout card by card in the new Workout Complete, and warm up for the weight you're actually lifting.
Flux Updates
Flux 8.6.0: get more from every session
Get to your workout faster, see what is working and give each set its own target. Explore Flux 8.6.0, with Light mode and clearer training insights.
Flux Updates
Flux 8.5.1: more choice, clearer routines, dependable completion
Five strength periodisation models, offline-first workout saving and redesigned Routine Details. Explore Flux 8.5.1, now free to try for 14 days.
Flux Updates
Flux Workouts v8.2.7 Release Notes
Flux has always been able to generate a personalised routine around your goals, schedule, experience, preferences, and available equipment. In 8.2.7, that option is joined by the Routine Library.
Flux Updates
Flux Workouts v8.2.3 Release Notes
Flux Workouts 8.2.3 is all about training that fits real life. Take a planned break without losing your streak thanks to the new Holiday Mode, get honest, on-device coaching from a fully reworked insight-led check-in, and let your sessions adapt to fatigue with a lighter, smarter touch.
Flux Updates
Flux Workouts v8.2.2 Release Notes
Flux Workouts v8.2.2 is one of our most practical updates yet. This release is all about the moments that matter in the gym: knowing exactly what to load on the bar, staying motivated between sessions, and seeing your training data clearly — without digging through menus.
Flux Updates
Flux Workouts v8.0.7 Release Notes
Whats new in Version 8.0.7. At a glance: Flux Labs integration, Calibration Mode Fix, and bug fixes.
Flux Updates
Flux Workouts v8.0.6 Release Notes
Whats new in Version 8.0.6. At a glance: HIIT Circuits, Timed Exercises, Improved Workout Generation and bug fixes.
Flux Updates
Flux Workouts - Introducing the NEW Workout Routine Generator
It's here! The new Workout Routine Generator is live in version 8.0.0. Build your own workout routines, choosing from Push, Pull, Legs, Upper, Lower and Full Body. Then tailor it to your needs, including super sets, giant sets, top set and back off sets and more.
Flux Updates
Flux Workouts v8.0.0 Release Notes
Whats new in Version 8.0.0. At a glance: Routine Generator, Top Set + Back Off Sets, new Insights charts, tighter Periodisation switching and more.