Running Doubles – Who Are They For

Running two sessions per day (doubles) is not just for advanced athletes. Doubles effectively accumulate volume while reducing per-session impact, support hormonal recovery, and allow training in a slightly depleted state for enzymatic adaptation. Use them strategically based on injury history and goals.

The Doubles Misconception

Most coaches treat doubles as an advanced technique: “Build to high mileage in singles, then add doubles.” This misses the point. Doubles can be an alternative way to accumulate volume at potentially lower injury risk, not just an elite optimization.

Two Theories on Why Doubles Work

Theory 1: Recovery Through Splitting

When you split a 12-mile run into 8 and 4 (or 7 and 5), you reduce per-session impact:

  • Lower muscle damage per session (research shows less muscle damage when splitting versus one long run at same volume)
  • Hormonal benefits: Growth hormone increases quickly during the first 40 minutes of easy running (550% spike), then plateaus. Two 40-minute runs = two spikes versus one spike followed by plateau. More frequent hormonal bumps may aid recovery.
  • Glycogen restoration: You get 4-8 hours between sessions to partially restore, so you start the second run less depleted
  • Cumulative fatigue: Lower per-session fatigue means more consistent training week-to-week

Result: You can sustain higher weekly volume with lower injury risk.

Theory 2: Training in a Depleted State

Counterintuitively, doing the second workout slightly depleted—not fully recovered—provides an additional stimulus:

Research on cyclists showed that doing easy + hard in the same day (easy morning, hard afternoon) produced greater mitochondrial and aerobic enzyme increases than traditional hard-easy alternating days, even though total performance improvements were the same.

Why? The second workout happens in a glucose-depleted, somewhat fatigued state, which signals the body to adapt more robustly to that specific stimulus.

This explains:
– Norwegian double-threshold (hard morning, hard afternoon)
– Canova’s special blocks (double hard workouts same day)
– Easy + hard same day strategies

Practical Applications

Doubles for Volume Accumulation

When: You need to hit higher mileage but run into injury issues with single long runs.

How: Do easy-easy doubles. Split your volume down the middle: if you’d normally do a 12-mile run, do 6-6 instead.

Who: Intermediate to advanced runners with injury history triggered by volume (not frequency).

Additional benefit: Masters runners can mix modalities—cross-train in morning, easy run in afternoon, get the volume without pounding impact twice.

Doubles for Recovery After Hard Workouts

When: You’ve done a hard session and need volume on recovery days.

How: Instead of one 12-mile run the day after a hard workout, do 6-6. More of those miles will be recovered-quality running rather than trudging through a long run while still fatigued.

Result: Better quality, better adaptation, lower injury risk.

Doubles for Aerobic Stimulus

When: You want more aerobic stressor beyond what single easy run provides.

How: Easy double (2x 40-45 min), split down middle or one longer one.

Why: Two separate hormonal/vascular bumps in one day.

Doubles for Adaptation (Advanced)

When: You’re advanced and seeking additional stimulus; used strategically, not constantly.

How: Easy + hard (morning/afternoon), or even double-threshold/double-workout. Requires careful recovery.

Risk: Can dig yourself a hole if not managed; requires athletes who recover well and have deep fitness.

Historical Context

Arthur Lydiard’s athletes actually used doubles, though it’s often overlooked. His maintenance periods included “shakeout jogs”—easy recovery runs paired with harder workouts same day. Even Lydiard’s pure base phase sometimes included doubles for accumulating total volume.

Mark Wetmore at Colorado popularized the “single run per day” approach to manage college athletes’ schedules and high-altitude stress. This became the American tradition, but it’s a context-dependent choice, not universal law.

Who Should Double

Beginner/Intermediate (Non-Elite)

Doubles aren’t necessary, but if you want to accumulate volume and have injury history with long runs:
– Try easy-easy doubles on recovery days
– Split volume rather than extending single runs
– Safer way to build weekly mileage

Masters Runners

Can use cross-training + run doubles to hit volume without repetitive impact:
– Morning: cross-train (cycling, swimming) + strength
– Afternoon: easy run
– Accumulates load safely

Advanced Runners

Can use easy-easy doubles for maintenance volume, or mixed (easy + hard) for adaptation stimulus. Don’t default to doubles; use them strategically when needed.

What NOT to Do with Doubles

  1. Don’t add doubles to already-high volume. If you’re running 50+ mpw in singles, adding doubles adds fatigue, not efficiency.

  2. Don’t do double-hard unless you’re advanced and need it. Most athletes benefit from “hard-easy” alternation; double hard is for specific adaptations (double threshold for example).

  3. Don’t do uneven splits for recovery. If your goal is reducing impact, split 50-50 (6 and 6). If your goal is one longer stimulus, do 7 and 3. Confused splits achieve neither.

  4. Don’t ignore recovery. Doubles only work if you’re recovered enough to handle them. Monitor sleep, nutrition, and overall fatigue.

Implementation Strategy

If you struggle with single long runs:
– Try easy-easy doubles (30/30 instead of 60)
– See if you tolerate it better
– Maintain total weekly mileage
– Assess injury markers after 4-6 weeks

If you’re fit and want more stimulus:
– Add one easy-easy double per week initially
– Monitor recovery
– Could shift to mixed (easy + workout) if stable

If you’re maxed out on fatigue:
– Don’t add doubles
– Look to intensity structure or periodization instead

Key Takeaway

Doubles aren’t a magic bullet, but they’re a legitimate tool for:
– Accumulating volume with lower impact
– Recovering better after hard sessions
– Getting multiple hormonal/vascular stimuli in one day

Most coaches underutilize them because of tradition. If volume is your constraint and you have injury patterns with single long runs, try doubles. If your issue is fatigue or recovery, doubles won’t help.

Think of it as another tool for your context, not an advanced secret reserved for elites.