Leg Speed Builder

Workout - Leg Speed Builder

• 15min @ 6'00''/km
• 12 lots of:
  • 400m @ 5'00''/km
  • 1min rest
• 10min @ 7'00''/km

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Quick rundown of Lee Grantham’s Unleash Your Potential: How Interval Training Can Shatter Your Personal Bests—definitely worth watching. We’ve summarized the essentials so you can take this workout for a spin right away. Grab the full video for the complete picture.

Key Points

• Interval training offers the quickest path to faster personal records across all distances (5K through ultra-marathon) by incorporating speed work and shifting your mental approach.
• Watch out for “gray-zone” easy runs that run faster than they should; dial them back to true recovery speed so you can bring full effort to your quality sessions.
• Short, rapid 400-meter repeats build leg speed, which then makes longer stretches and goal-race pace feel much more attainable.
• Ramp up the number of reps steadily while holding your 400-meter split around 70 seconds (roughly 1:10 for 800 meters) and maintaining 60 seconds between efforts.

Workout Example

Warm‑up: 10–15 minutes easy running plus dynamic stretches
Main set: 20 × 400 m @ ~70 s each (or 1:10 per 800 m) with 60 s recovery.
Build-up: begin with 10–12 reps at target pace, then add 2–3 reps weekly until reaching 20.
Cool‑down: 10 minutes easy running.

Practical Tips

• Hold your easy runs at true recovery speed to sidestep the “gray-zone” trap.
• Think of speed work as a craft—maintain your practice schedule even when races get postponed.
• Pay attention to how your body responds; your heart rate will climb, but the effort should feel controlled.
• Lean on the Pacing app to dial in your 400-meter pace based on your current fitness level.

Closing Note Run this session once this week, adjust the 400-meter split within the Pacing app to match your own fitness, and track your marathon pace gains. You have everything you need—now go break that PB!

References

• Unleash Your Potential: How Interval Training Can Shatter Your Personal Bests - YouTube (YouTube Video)