Warmup
- 1.75 miles at a conversational pace, no faster than 8:25/mi
- Dynamic drills: high knees, butt kicks, leg swings, A-skips
- 4 x 100m strides, building into the main set
Main Set
6 rounds of alternating quarters, 90 seconds walking rest between rounds.
Each round:
- 0.25 mi at threshold effort — comfortably hard, a pace you could hold for about an hour
- 0.25 mi at 5K effort — smooth and strong, the pace you’d race a 5K at today
Run the two quarters back to back with no break between them. The 90 seconds walking rest comes only between rounds — so one round is a half mile of continuous running with a gear change in the middle.
As a rough reference: a runner whose 5K pace is around 6:35/mi would run the slower quarter near 7:45/mi. Use your own paces, not these. What matters is the gap between the two efforts staying consistent round to round.
Cooldown
- 1.75 miles at a conversational pace, or slower
- 5 minutes of stretching: calves, hamstrings, hip flexors, quads
Coach’s Notes
Alternations train you to shift gears under fatigue without ever fully recovering. The “slow” quarter isn’t a rest — it’s still threshold work. The fast quarter is where the stimulus lives, but the slow quarter is what makes it hard.
Two common mistakes. First, running the slow quarter too slow to “bank” energy for the fast one. That turns the workout into intervals with jog recovery, which is a different session. Hold the slower quarter at a pace you could sustain for a 10K. Second, running the fast quarter too fast in the early rounds. If round 6 falls apart, you went out wrong. Rounds 5 and 6 should look like rounds 1 and 2.
If you can negative-split the fast quarters across the session, you nailed it.
Scaling
Newer runners: 4 rounds instead of 6. Pick your own two paces — the faster quarter should feel like 5K effort, the slower like a comfortable tempo. The gap matters more than the exact numbers.
Advanced runners: 8 rounds, or tighten the rest to 60 seconds. Another option: close the gap between the two efforts — run the slow quarter closer to 10K pace while holding the fast quarter at 5K pace. Smaller gap, harder workout.