Swim-Run Aquathlon Intervals: 4 × (300m Swim + 800m Run)

Session Overview

This challenging 75-minute session builds aquathlon fitness and trains the swim-to-run transition by alternating pool swims with road runs in repeated efforts. Four rounds of 300m pool swim followed immediately by 800m run develop the ability to shift from horizontal swimming to upright running quickly — a key skill that’s often undertrained by triathletes.

What You’ll Need

• 25m or 50m pool with outdoor access nearby
• GPS watch (waterproof)
• Running shoes left poolside
• Trisuit or quick-change kit — no wetsuit needed

Warm-Up (10 minutes)

200m easy freestyle in the pool, then exit and jog 400m at easy pace to warm the running legs. Return to the pool. This short swim-run warm-up activates the muscles and cardiovascular system you’ll use throughout the session.

Main Set

Perform all four rounds with no more than 60 seconds between swim exit and the start of your run. The transition is part of the session — don’t dawdle. Rest 90 seconds between each complete round (after the run, before diving back in).

• Round 1: 300m pool swim (moderate effort) → exit immediately → 800m run at 70.3 race effort
• Round 2: 300m pool swim (moderate effort) → exit immediately → 800m run at 70.3 race effort
• Round 3: 300m pool swim (moderate effort) → exit immediately → 800m run at 70.3 race effort
• Round 4: 300m pool swim (moderate effort) → exit immediately → 800m run at Olympic race effort

Cool-Down (5 minutes)

200m easy backstroke in the pool to flush the legs, then 400m walk outside to lower heart rate. Stretch calves and hip flexors — the standing swim exit puts stress on both. Rehydrate immediately with electrolytes.

Coaching Notes

• The first 200m of each run will feel awful — your legs are full of blood from swimming horizontal. Push through the first minute and you’ll find your running legs.
• Beginners: reduce to 3 rounds of 200m swim + 600m run with 2-minute rest between rounds.
• Practise minimal transitions — kick your shoes on without stopping, don’t tie laces mid-session.
• This session is excellent prep for aquathlon racing (run-swim-run format) and for building T1 confidence.
• Target swim RPE: 6–7. Target run RPE: 7–8 (building to 8 in round 4).