Swim Squad: Threshold Swimming

Swim Squad: Threshold Swimming

This winter we are focusing on technique and speed. Short, fast Alactic Sprints and short sets of VO2 Max work. We’ve spoken about both of these in our previous posts.

Threshold Swimming

We are also going to complement these shorter, faster efforts with some threshold swimming.

Threshold swimming is the pace you can hold for a moderate distance with effort but without exhaustion. It sits between easy endurance work and VO₂ Max – hard enough to challenge your aerobic system, but sustainable enough to maintain quality technique. A practical way to estimate it is your average 100m pace from a best-effort 1500m swim or a 400/200 time trial.

Benefits of including threshold work

• Aerobic endurance: teaches your body to sustain a strong pace for longer.
• Lactate tolerance: improves muscles’ ability to manage fatigue.
• Stroke resilience: helps maintain smooth, strong technique under stress.
• Bridge between speed and endurance: connects shorter bursts (alactic/VO₂ Max) to steady aerobic work.

How it should feel

• Effort: roughly 7–8/10 – strong, controlled, and challenging, but not all-out.
• Breathing: deeper than normal; you can speak in short phrases but not full sentences.
• Stroke: technique should remain smooth, even as your body works hard.
• Consistency: it’s the pace you could just about hold for a full set – for example, 10 × 100m with short rests.

Types of threshold swim sets

Here are some examples you might see in sessions:

• 50m reps: 20s rest, 20×50m, fast but controlled.
• 100m reps: 25–30s rest, building from 10×100m → 20×100m.
• 200m reps: 40–45s rest, building from 5×200m → 10×200m.

Key points for all sets:

• Pace should feel like 7–8/10 effort – hard but sustainable.
• Focus on consistency: aim for roughly the same time each rep.
• Technique comes first – better to slow slightly than let stroke quality drop.

Rest & “Check Your Pace”

If you need more rest than planned, it usually means one of two things:

• Your pace is too fast – you’ve crossed into VO₂ Max territory.
• Your aerobic fitness needs more work – your body can’t yet sustain that pace for all reps.

Threshold work is about controlled, repeatable effort. Maintaining consistent reps with good form will give you more benefit than trying to hit a pace you can’t sustain.

Finding the Right Pace

If you are trying a threshold set for the first time it can be tricky to find the right pace. Are you going too fast and likely to blow up? Are you swimming too conservatively and missing out on some benefits?

Usually, it takes a few attempts to find your ideal pace / effort level.

• Use the first attempt as a guide: swim the set at what feels like threshold. Take note of where fatigue hits.
• Adjust gradually next time – slightly increase pace once you can hold all reps comfortably.
• Watch for cues beyond the clock: breathing harder than easy swimming but controlled, smooth stroke, and ~7–8/10 effort.
• If building sets over weeks (10×100m → 20×100m), focus on maintaining pace consistently, then increase pace slowly as fitness improves.

In Short …

Threshold swimming is all about controlled, high-quality effort. The right pace, paired with well-chosen rest intervals and gradual adjustments, allows you to build speed, efficiency, and endurance in a way that’s challenging but sustainable.