“I couldn’t make my times” is a common response I heard after asking fellow triathletes about their swim workouts. I decided to investigate why this was happening. My conclusion: Triathletes only have one speed because they do not understand the concept of balancing pace and rest.
I’ve watched many triathletes swim as hard as possible and achieve the same pace for 100m as they would for 400ms. This would be like Usain Bolt running the same pace for a 100m as he would for 400m!
Gold Standard: The 400m Time Trial
Using the 400m distance as a swimming time trial has been around for decades. This distance, although not routinely used in triathlon, is useful because it is a close representation of V02max. V02max is the maximal ability of the body to use oxygen by the muscles. The 400m swim test was described as the ‘gold standard’ for estimating maximal aerobic speed.
After swimming the 400m time trial you can predict two other intensities that are useful for improving overall swim speed. The first intensity is the lactate threshold, or, also called maximal lactate steady state (MLSS). The second intensity is the anaerobic threshold (AeT).
MLSS is defined as the highest speed that can be maintained with a consistent appearance and disappearance of lactate in the blood. Studies have shown that MLSS occurs after swimming as hard as possible for about 60 minutes or, about 85% of V02 pace.
Between V02 and MLSS is the AeT. Research shows that trained swimmers can sustain this pace for about 30 minutes, or 92% of V02 pace. Basically swimming at this intensity is not as hard as V02 but harder than MLSS.
Below is an example of how to calculate the MLSS, AeT, and V02 paces based on finishing time from the 400m time trial.
EXAMPLE: Athlete A swims 6 minutes for a 400m time trial.
V02 pace = 1:30min/100m
AeT pace = 1:37min/100m
MLSS pace = 1:43min/100m
To calculate the AeT pace, take the V02 pace and add 8% to it:
1:30 + (1:30 * 0.08) = 1:37
With these 3 intervals you can develop top end speed (V02), endurance (AeT) and understand your recovery speed (MLSS).