Vertical Kicking Drill: Strengthening Butterfly Legs

Build Power, Timing, and Core Control — One Dolphin Kick at a Time 

In butterfly, the legs aren’t just along for the ride — they’re the engine of propulsion. While the arms provide lift and direction, it’s the dolphin kick that drives momentum, powers breakouts, and sustains rhythm through every grueling cycle. Yet many swimmers neglect leg strength, focusing instead on pull technique or breath timing.

Enter the Vertical Kicking Drill — a deceptively simple but profoundly effective exercise that isolates the core-driven undulation essential to elite butterfly. Performed in deep water with arms crossed or raised, this drill builds explosive leg power, refines timing, and strengthens the neuromuscular connection between chest, core, and feet.

In this guide, we’ll show you how to master vertical kicking for butterfly — with progressions, coaching cues, and programming tips to transform your legs from a liability into your greatest asset.

🦋 Why Vertical Kicking Is Essential for Butterfly

Unlike flutter or breaststroke kicks, the dolphin kick is a full-body wave that originates in the chest and pulses down through the hips, knees, and feet. Vertical kicking removes the support of forward motion, forcing you to:

• Generate propulsion purely from core and leg drive

• Maintain rhythm without glide phases

• Build endurance in the exact muscles used in butterfly

• Develop breath control under physical stress 

“If you can’t kick vertically, you’re not ready to fly.”— Coach Bob Bowman  

🛠️ How to Perform the Vertical Kicking Drill

Basic Form:

1. Position: In deep water (at least 7 feet), cross arms over chest or raise them overhead (more challenging)

2. Body: Keep head above water, eyes forward, core braced

3. Kick: Initiate movement from the chest → hips → legs → feet

   • Recovery: Knees bend slightly as hips rise

   • Power: Snap legs together downward with pointed toes 

4. Rhythm: Small, fast, continuous undulations — not large, slow bends 

🎯 Cue: “Press your chest down like you’re nodding ‘yes’ — let your hips follow.”  

📈 Progressions for All Levels

🔹 Beginner: Arms Crossed, Short Intervals 

• Focus: Feel the wave motion, build confidence

• Sets: 4–6 x 20 seconds, 40s rest

• Tip: Use short fins to help with rhythm 

🔹 Intermediate: Arms Overhead, Controlled Breathing 

• Focus: Increase core engagement, add breath control

• Sets: 6–8 x 30 seconds, 30s rest

• Cue: “Breathe every 3–4 kicks — steady exhale underwater” 

🔹 Advanced: Resistance + Sprint Bursts 

• Add light ankle weights (use cautiously) or hold a small medicine ball

• Sets: 8–10 x 15 seconds MAX effort, 60s rest

• Goal: Explosive power for race starts and breakouts 

⚠️ Safety Note: Never use heavy resistance. Stop if you feel lower back strain.  

💪 5 Key Benefits of Vertical Kicking for Butterfly

1. Builds Core-Driven Undulation 

• Teaches swimmers to initiate the kick from the chest — not the knees

• Eliminates “bicycling” or knee-dominant kicks that kill momentum 

2. Strengthens Hip Flexors and Glutes 

• These muscles power the upward phase of the dolphin kick

• Critical for explosive breakouts off walls 

3. Improves Breath-Kick Timing 

• Forces swimmers to time inhalation with the kick’s power phase

• Reduces breath-holding and panic 

4. Enhances Ankle Flexibility and Foot Snap 

• Pointed toes and quick closure maximize propulsion

• Vertical position highlights floppy or tense ankles 

5. Develops Lactate Tolerance 

• High-intensity vertical sets simulate the metabolic stress of 100/200 fly

• Builds mental and physical resilience for the “grind zone” 

🏊 Sample Vertical Kicking Sets

Power Builder (Pre-Main Set) 

• 6 x 30s vertical kick (arms crossed)

• Rest: 30s

• Focus: “Small, fast, chest-led” 

Race Simulation (Butterfly Focus) 

• 4 x 45s vertical kick (arms overhead)

• Rest: 45s

• On last 10s of each rep, sprint

• Mimics final 25m of a 200 fly 

Endurance Challenge (Advanced) 

• 3 x 60s vertical kick

• Rest: 60s

• Maintain consistent rhythm — no slowing 

🧠 Coaching Cues That Work

🦋 “Chest leads. Hips chase. Feet finish.”

💥 “Kick like a dolphin — not a frog.”

🧱 “Core tight, knees soft, toes pointed.”

⏱️ “Fast feet, quiet splash.”

🌬️ “Breathe on the snap — not before.”  

⚠️ Common Mistakes — And How to Fix Them     

Kicking from knees	Creates drag, kills rhythm	Cue: “Initiate from your sternum”
Holding breath	Causes early fatigue	Add steady bubble exhale underwater
Arms flailing	Wastes energy, disrupts balance	Cross arms firmly over chest
Over-bending at hips	Looks like a jackknife — inefficient	Reduce amplitude; focus on wave flow
Dropping head	Strains neck, sinks hips	Keep eyes forward, chin slightly up

📊 How to Track Progress

• Duration: Can you hold form for 10s longer?

• Recovery Time: Less rest needed between reps?

• Underwater Kick Power: Faster breakout off walls?

• Race Splits: Improved 25m fly times (especially off starts/turns)? 

💡 Film your vertical kick: Compare hip movement and kick amplitude monthly.  

💬 Pro Insight from Elite Coaches

“I use vertical kicking as a litmus test. If a swimmer can’t hold 45 seconds with good form, they’re not ready for high-volume fly sets.”— Dave Salo, USC Trojan Swim  

“The best butterflyers don’t have the strongest legs — they have the smartest undulation.”  

Final Thoughts

Vertical kicking isn’t just a drill — it’s a diagnostic tool, a strength builder, and a rhythm teacher all in one. It strips away the distractions of forward motion and forces you to confront the raw mechanics of the dolphin kick.

So the next time you step into deep water, don’t just splash. Press your chest down.Snap your feet together.And let every vertical kick be a step toward stronger, smoother, more powerful butterfly.

Chest down. Hips up. Feet snap. Breathe. Repeat. 

Because in butterfly, flight begins not with the arms —but with the wave that starts in your core. 🦋💙