5000m Pool Endurance Swim: Long-Course Aerobic Build Session

Session Overview

This 5000m pool endurance session is designed for advanced swimmers and long-course triathletes building the aerobic base for Ironman or 70.3 races. Clocking in at approximately 90-100 minutes, you’ll develop the sustained aerobic capacity needed to hold strong form throughout a race-distance swim and beyond.

What You’ll Need

• A pool with consistent 25m or 50m lanes
• Pull buoy (for part of the set)
• Swim fins (optional — for kick sets)
• Waterproof watch with lap counter

Warm-Up (500m)

Start with 200m easy freestyle focusing on long, relaxed strokes and bilateral breathing. Follow with 8x25m alternating catch-up drill and easy freestyle. Finish with 100m pull buoy to settle your upper body rhythm before the main set.

Main Set

This main set totals 4,000m split across continuous blocks and structured repeats. Keep your effort at a comfortable Zone 2-3 pace throughout — this is an endurance session, not a threshold workout.

• 1,000m continuous at easy aerobic pace (Zone 2) — focus on rhythm and relaxed breathing
• Rest 45 seconds
• 4x400m at your CSS (critical swim speed) pace with 30 seconds rest between each
• Rest 60 seconds
• 1,000m continuous — aim to match or slightly exceed your opening 1,000m pace
• Rest 45 seconds
• 8x100m with 15 seconds rest — hold consistent pace across all 8 reps
• 500m pull buoy continuous — hold strong catch position throughout

Cool-Down (500m)

Swim 300m easy backstroke or mixed stroke to flush lactic acid and relax your shoulders. Finish with 200m gentle freestyle, focusing on elongating each stroke and slow controlled breathing. Take 2-3 minutes for poolside shoulder and chest stretches before getting out.

Coaching Notes

• The goal is consistency — your 400m repeats should be within 5 seconds of each other. If you’re blowing up on the third rep, you started too hard.
• Don’t overcomplicate your breathing. Find a rhythm in the continuous blocks (every 3 strokes works for most) and stick with it.
• Make it easier: Replace the 4x400m CSS block with 4x400m at easy pace and drop total distance to 4,000m.
• Make it harder: Add 10-15 seconds to your CSS pace for the 400m reps, or extend the opening 1,000m to 1,500m.
• RPE should average 6-7 out of 10. If you’re hitting 9s in the continuous blocks, ease off — you’ll need to sustain this level of effort in a race.