The Mathematics of Freestyle Speed: How the Total Immersion Formula Helps Master Swimming Tempo

From Chaos to Control – Why Swimming Tempo Isn't Random

Most recreational swimmers approach training intuitively: "swimming faster = working harder." The Total Immersion (TI) method completely reverses this thinking. Instead of fighting the water, you learn to "outsmart" it through precise control of two variables: stroke count (SPL) and the tempo of each stroke.

Total Immersion founder Terry Laughlin developed a simple mathematical formula that allows you to predict your time for any distance with second-level accuracy – no guessing, no "feeling."

The TI Speed Formula – Decoded

The basic relationship looks like this:

P(PL) = (SPL × Tempo) + T(G)

Where:

• P(PL) – Pace per Pool Length (time for one pool length)
• SPL – Strokes Per Length (stroke count per length)
• Tempo – seconds per stroke (cycle)
• T(G) – Time of Glide (glide time after pushing off the wall)

Practical Example – 25-Meter Pool

Let's assume a standard glide time T(G) = 3 seconds. Here's how different SPL and Tempo combinations translate to the same 20-second time per length:

What does this mean in practice? You can swim at an identical pace of 20 sec/25m, but in completely different ways:

• 15 strokes at 1.13s tempo – long, smooth stroke, high efficiency
• 18 strokes at 0.94s tempo – shorter stroke, faster frequency

Which version is better? It depends on the distance and your predispositions. But the key is that both produce the same result – and you can consciously train both.

From 25 Meters to 100 Meters – How to Calculate Pace

Time for a single pool length is just the beginning. Most swimmers think in terms of 100 meters or pace per minute. Here's how to convert:

Simple Calculation

100m time ≈ (25m time × 4) + turn correction

For recreational swimmers, turns add about 1-2 seconds each (3 turns per 100m). For skilled swimmers with flip turns – practically zero.

Conversion Table: 25m → 100m → pace/100m

What Does This Mean for Your Training?

Going back to our SPL × Tempo table example:

• 20 sec/25m translates to a pace of about 1:20-1:25/100m
• This pace allows you to swim 1000m in ~13:20-14:10
• Or 1500m (standard triathlon distance) in ~20:00-21:15

Knowing this relationship allows you to plan realistic race goals. If you want to swim 1500m under 30 minutes, you need a pace of about 2:00/100m, which means 30 seconds per length – and now you know exactly which SPL × Tempo combinations make that possible.

Why a Swimming Metronome Changes the Game

Without an external signal, maintaining a steady tempo is nearly impossible. Your brain naturally "wanders" – sometimes speeding up, sometimes slowing down, often without you even knowing.

A tempo trainer (swimming metronome) solves this problem. You set a tempo, for example 1.10 seconds per stroke, and get an audio or vibration signal with each cycle. Your task? Synchronize your stroke with the signal.

The result? After a few weeks of training with a metronome:

• Your body "remembers" the exact tempo
• You can maintain a steady speed without looking at your watch
• You can consciously manipulate SPL and Tempo to achieve your target time

How to Use the Formula in Training

Step 1: Measure Your Baseline Values

Swim 4×25m at a comfortable pace. Count strokes (SPL) on each length. Measure time.

Step 2: Calculate Your Current Tempo

Tempo = (Time per length – Glide time) ÷ SPL

Example: You swim 25m in 22 seconds, take 16 strokes, glide lasts ~3 seconds.

Tempo = (22 - 3) ÷ 16 = 1.19 sec/stroke

Step 3: Set the Metronome and Train

Start with your current tempo. For several workouts, focus solely on synchronizing with the signal while maintaining the same stroke count.

Step 4: Gradually Speed Up

Reduce tempo by 0.02-0.03 seconds. Can you maintain the same SPL? If yes – you just swam faster without additional effort.

The "Green Zone" Concept – Your Effective SPL Range

Total Immersion introduces the concept of the Green Zone – the optimal SPL range for your height. This is the stroke count at which your technique is most efficient.

Approximate Green Zone values for freestyle in a 25m pool:

• Height 160-170 cm (5'3"-5'7"): 15-19 SPL
• Height 170-180 cm (5'7"-5'11"): 14-18 SPL
• Height 180-190 cm (5'11"-6'3"): 13-17 SPL
• Height >190 cm (>6'3"): 12-16 SPL

If your SPL is significantly higher than the Green Zone for your height, you have room for technique improvement (balance, torso rotation, streamline). If it's within range – focus on tempo training.

Practical Training Set with the TI Formula

Warm-up: 200m freestyle, counting strokes

Main set:

• 4×50m @ Tempo 1.20 – goal: maintain steady SPL
• 4×50m @ Tempo 1.15 – does SPL increase? By how much?
• 4×50m @ Tempo 1.10 – comfort limit

Rest: 10 metronome "beeps" between sets (instead of looking at the clock)

Cooldown: 100m with maximum stroke length, no metronome

BeatBuddy Pro – Next-Generation Metronome for TI Swimmers

Classic tempo trainers offer one tempo per workout. BeatBuddy Pro goes further – you can program an entire interval series: 30 seconds @ 1.20, then 30 seconds @ 1.15, then 30 seconds @ 1.10.

Additionally, you get triple feedback: piezo sound, vibration, and LED signal. In a noisy public pool, you can rely on vibration; in calm open water – on sound.

Integration with Garmin watches via Bluetooth Low Energy is already available, and ANT+ protocol support is currently in development. This will enable even broader compatibility with the Garmin ecosystem and training data synchronization with the BeatBuddy Lens app.

Summary: Mathematics, Not Magic

The Total Immersion formula isn't theory – it's a practical tool. Knowing the relationship P = (SPL × Tempo) + T(G) allows you to:

• Precisely plan race pace
• Consciously work on stroke efficiency
• Eliminate guesswork from training

A swimming metronome is your partner in this process. Without it, the formula remains just numbers on paper. With it – it becomes a tool for transforming your swimming.

Article created in collaboration with Total Immersion coaches. Graphics represent original materials from totalimmersion.net.

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