Swimming Anaerobic Threshold Training: Designing Workouts for Lactate Threshold Swimming Speed

Introduction

Many swimmers hit a common plateau after building their aerobic base: they can swim long distances at a decent pace, but once they reach race pace for 400m or 800m, they can’t hold the rhythm. This usually means the “anaerobic threshold” hasn’t been fully developed. Anaerobic Threshold training is the bridge connecting the aerobic base with high-intensity explosive power, and it’s a key zone for improving race pace. This article will introduce the theory of lactate threshold swimming speed and provide practical workout designs.

The Relationship Between Lactate Threshold and Swimming

Lactate Threshold (LT) refers to the critical point where blood lactate concentration begins to rise rapidly as exercise intensity increases. In swimming, this typically corresponds to a speed zone where blood lactate is around 2–4 mmol/L.

Why is anaerobic threshold training so important?

• Increasing lactate threshold speed means maintaining aerobic metabolism at faster speeds
• Delaying fatigue accumulation, giving you more power in the latter half of 800m and 1500m events
• Increasing the muscles’ ability to clear lactate (through increased mitochondrial density)
• Especially important for triathletes, as swim segment speed directly affects energy distribution for the rest of the race

How to Determine Lactate Threshold Speed?

Method 1: Using CSS as a Baseline

If you’ve completed a CSS test (see previous article), your anaerobic threshold speed typically falls within:
$$LT \text{ speed} \approx CSS ± 5 \text{ sec/100m}$$

In other words, when swimming at CSS pace, you’re right around your lactate threshold—this is the simplest estimation method.

Method 2: On-Site Lactate Testing

Professional athletes can commission sports science institutions to conduct blood lactate testing. In Taiwan, some university physical education departments (such as NTNU and NTSU) offer these services, with fees around NT$1,500–3,000.

Method 3: Subjective Feel Assessment

Subjective characteristics of anaerobic threshold intensity:

• RPE 6–7/10, noticeably deeper breathing but can still speak briefly
• Feels “somewhat hard but still manageable”
• After finishing a 200m repeat, it takes 30–60 seconds to regain the ability to speak normally

Anaerobic Threshold Workout Design

Core principle of anaerobic threshold training: maintain a pace that is “near maximal effort but not breaking down,” with each repeat typically 200–400m and short rest intervals (30–60 seconds).

Workout 1: Progressive Threshold Set (Suitable for Beginners)

Workout 2: Tempo Swim

Suitable for swimmers with 3+ months of foundation:

• Warm-up: 600m (including 4×50m activation)
• Main set: continuous 800m at threshold speed (complete in one go, no stopping)
• Secondary set: 4×200m, 30 sec rest, pace 2–3 sec/100m faster than the 800m
• Cool-down: 400m easy swim
• Total: Approx. 2,600m

Workout 3: Pyramid Threshold Set

Maintain CSS ± 5 sec pace throughout, with a main set total of 1,400m.

Periodization for Threshold Training

Anaerobic threshold training is relatively high intensity—limit it to 2 sessions per week, with other training days dedicated to aerobic base or recovery swimming:

• Monday: Aerobic base (low intensity)
• Wednesday: Anaerobic threshold workout
• Friday: Aerobic base or technique swimming
• Saturday: Anaerobic threshold workout (or race)

After 3 consecutive weeks of threshold training, schedule 1 recovery week (reduce volume by 30%) to allow the body to supercompensate.

Practical Tips

1. Don’t try to “break records” on every repeat: The goal of threshold training is consistency, not being fastest on each repeat. The later repeats should be within 3 sec/100m of the earlier ones.
2. Don’t make rest intervals too long: Rest exceeding 90 seconds will cause heart rate to drop significantly, losing the threshold stimulus effect.
3. Pace clocks or swim watches are great tools: Most pools in Taiwan have pace clocks on the wall—practice controlling your pace by timing.
4. Combine with technique work: If your technique breaks down at threshold speed, slow down and fix your form first; otherwise, bad habits will be reinforced.
5. Nutrition: Consume a small amount of carbohydrates (such as a banana or rice ball) 2 hours before threshold training to help maintain intensity in the latter part of the workout.

Conclusion

Anaerobic threshold training is the most critical piece of the puzzle in swimming fitness improvement. With a solid aerobic base plus systematic lactate threshold workouts, you’ll find that speeds you once thought were “too hard to maintain” gradually become comfortable paces. If amateur swimmers in Taiwan can consistently perform 1–2 threshold sessions per week, they can see significant improvements in speed and endurance within 6–8 weeks.

Related Reading

• Swimming Anaerobic Lactate Training: How to Do High-Intensity Intervals in the Pool
• Building an Aerobic Base in Swimming: CSS Critical Speed Training Methods
• Swimming Anaerobic Threshold Training: T-pace Testing and Workout Design
• Swimming Interval Training: Calculating and Applying CSS (Critical Swimming Speed)