Why IM Training Belongs in Every Program
Even pure freestylers benefit from IM work. Swimming all four strokes in one set forces stroke balance—shoulders, hips, and kick patterns that freestyle alone won't touch. It also builds aerobic range across different neuromuscular demands, since fly and breaststroke tax the upper body and core differently than back and free. And IM work exposes weakness fast. A swimmer can hide a mediocre breaststroke in a free-heavy program. Put that same swimmer on a 200 IM and the weak 50 shows up immediately, in the stroke count and in the split.
Transitions and Turns
The turns inside an IM are where races are won or lost, and they're the most under-trained part of most programs.
- Fly-to-back: swimmers rush the last fly stroke and miss the wall, or under-rotate into the back turn. Drill the approach separately—5-6 strokes of fly into a touch-and-rotate, no swim after.
- Back-to-breast: this is the hardest transition technically. The swimmer has to find the wall blind, execute a backstroke flip or pullout-style turn, and be square for a breaststroke pullout immediately. Practice this turn in isolation, 8-10 reps, focusing on the underwater dolphin kick into the pullout.
- Breast-to-free: usually the easiest, but sloppy breaststroke finishes (gliding in flat instead of accelerating to the wall) cost time here too.
A simple transition set: 8 x 50 on the turn only — swim into the wall from 15m out, execute the transition, swim 15m out the other side. Rest 20 seconds. This isolates technique without the fatigue of a full IM rep.
IM Order and Reverse IM
IM order (fly-back-breast-free) is race-specific. Use it when the intent is pacing, transitions, or race simulation.
Reverse IM (free-breast-back-fly) changes the training effect. Backstroke and fly come later in the set, when the swimmer is already fatigued from free and breast. This builds strength and technique under fatigue in the two strokes that usually break down first in a real IM. Reverse IM is also useful for swimmers who go out too fast on fly and blow up by breaststroke—it teaches pacing from the back end.
Example: - 4 x 200 reverse IM (50 free / 50 breast / 50 back / 50 fly), best average, 30 seconds rest. Intent: aerobic IM fitness with the weak stroke (often fly or back) trained under fatigue instead of fresh.
Rate vs. Distance per Stroke
Decide what you're training before you write the set. Longer stroke segments (100s or 200s of a single stroke inside a broader IM-themed practice) build stroke-specific aerobic capacity. Short, race-pace 25s and 50s inside an IM rep build stroke rate and transition speed. Don't mix intents in the same rep—a 200 IM done for aerobic threshold and a 200 IM done for race-pace splits require different send-offs and different coaching cues.
Pacing the 200 and 400 IM
Most swimmers go out too fast on fly and pay for it on breaststroke, the slowest stroke in the race. Teach even effort, not even split—fly should feel controlled, not sprinted.
For a 200 IM goal of 2:10: - Fly: 30.5 - Back: 34.5 - Breast: 38.0 - Free: 27.0
That breaststroke split is usually the largest single chunk of the race and the easiest to lose time on if the swimmer arrives fatigued from an all-out fly. Practice broken 200 IMs on this exact split target: 50 fly, 15 seconds rest, 50 back, 15 rest, 50 breast, 15 rest, 50 free—hitting the goal splits before ever swimming it straight through.
For a 400 IM, the pacing conversation shifts to management over four 100s rather than four 50s. The 100 fly needs to be aerobically controlled, not raced, or the rest of the swim unravels.
Building the Weak Stroke Without Wrecking the Set
The instinct is to hammer the weak stroke with extra volume. That works until it turns into junk yardage with breakdown technique. Better approach: keep the weak stroke's volume similar to the others, but change its role in the set.
- Swim the weak stroke first, when fresh, to reinforce technique.
- Swim it inside a reverse IM to build it under fatigue once technique is solid.
- Use short rest intervals on the strong strokes and generous rest on the weak one, so quality doesn't collapse.
Example: 6 x (50 weak stroke @ technique pace, 20 seconds rest / 50 strong stroke @ moderate pace, 10 seconds rest). Intent: equal volume, unequal demand, so the weak stroke gets attention without turning into a fatigue dump.
Example Sets by Level
Age group (10-12), IM introduction 8 x 50 IM order by 25s (25 fly / 25 back, 25 back / 25 breast, etc.), 30 seconds rest. Intent: transition mechanics, not speed.
Age group (13-14), aerobic IM base 5 x 200 IM, descend 1-5, 20 seconds rest. Intent: aerobic capacity with pacing discipline.
Senior, race-pace IM 3 rounds: 50 fly @ goal pace + 10 rest, 50 back @ goal pace + 10 rest, 50 breast @ goal pace + 10 rest, 50 free all-out, 2:00 rest between rounds. Intent: race-pace splits and finishing speed.
Senior, reverse IM fatigue set 4 x 200 reverse IM, holding best average within 3 seconds rep to rep, 30 seconds rest. Intent: technical hold under aerobic fatigue, especially on back and fly.
When I'm building IM work into a week, I use SwimIQ to check that a set actually trains what I intend—that a reverse IM main set lands in the right energy system zone, and that rest intervals match the technical or aerobic goal instead of just feeling right on paper.