For who
For swimmers training for the 400 IM who want to build strength, stamina, and efficiency across all four strokes. Perfect for those with race experience aiming to sharpen IM performance.
24
Workouts
3000
Avg. Meters
53
Avg. Mins
Start with your swimming goals and current pace. DuoSwim creates a personalised swimming plan to help you train with purpose.
Race Ready
Race Pace · IM · 200-400
First swim
IM Foundations
2,400 m 42 min
Mid-plan
Race-Ready Challenge II
3,500 m 61 min
Final swim
400 IM Simulation
2,500 m 44 min
SYNCS WITH:
For who
For swimmers training for the 400 IM who want to build strength, stamina, and efficiency across all four strokes. Perfect for those with race experience aiming to sharpen IM performance.
Training focus
Progressive workouts targeting aerobic stamina, race pacing, and stroke consistency, built to elevate your IM from start to finish.
What to expect
Targeted IM sets that develop race pace, smooth transitions, and stroke rhythm across all four strokes. Designed for the 400 IM, but beneficial across all IM events.
Equipment you need
You can adjust the equipment to suit your preferences and available gear.
Download DuoSwim, start your first workout, and build momentum this week.
Step 1
Download DuoSwim and log in to unlock your plan and workout guidance.
Step 2
Start your recommended plan or choose the one that fits your goal and schedule.
Step 3
Follow your workouts with clear pacing, intervals, and progress tracking built in.
Step 4
Review your completed workouts and progress in DuoSwim.
Distances from the first 12 workouts in this plan. See the full workout list below.
Preview the structure of this plan with workout names, estimated duration, and distance.
IM Foundations
42 min · 2400m
400 IM Pace Intro
40 min · 2300m
Freestyle Efficiency
44 min · 2500m
IM Hybrid
44 min · 2500m
Backstroke Stamina
46 min · 2600m
Race-Ready Challenge I
56 min · 3200m
Breaststroke Surge
49 min · 2800m
Descend & Hold
53 min · 3000m
Threshold Zone
53 min · 3000m
Fly Flow & Surge
53 min · 3000m
Medley Flow
56 min · 3200m
Race-Ready Challenge II
61 min · 3500m
All Strokes Mixer
53 min · 3000m
Hold & Drop Free
63 min · 3600m
IM Transitions
70 min · 4000m
400 IM Race Pace
61 min · 3500m
Backstroke Power
49 min · 2800m
Yellowline Threshold
70 min · 4000m
Flow & Fly Power
58 min · 3300m
Base Endurance
56 min · 3200m
Breaststroke Drive
53 min · 3000m
Broken 400 IM’s
60 min · 3400m
Race-Ready Tune-Up
42 min · 2400m
400 IM Simulation
44 min · 2500m
We recommend Strength Gains to pair with this plan — building power and muscular control to support race performance across all strokes.
Answers to common questions about this plan, equipment, pacing, and getting started.
For swimmers training for the 400 IM who want to build strength, stamina, and efficiency across all four strokes. Perfect for those with race experience aiming to sharpen IM performance.

A clear, structured path that helps you train with confidence and keep progressing week by week.
First week free. Cancel anytime.