When should I start running doubles?

Most coaches suggest waiting until you're consistently running 50-60+ miles per week in single runs. At that point, adding miles via doubles is often easier on the body than making single runs longer. If you're running less, focus on single-run volume first.

How should doubles be structured?

Typically: one primary run (normal training run) and one secondary run (short, easy, 20-40 minutes). The secondary run is pure volume—no quality work. Most runners do the primary run in the morning and the easy double in the afternoon/evening, or vice versa.

Does running twice burn more calories?

Total calorie burn depends on total mileage, not frequency. Running 8 miles in two 4-mile runs burns approximately the same as one 8-mile run. The metabolic 'afterburn' (EPOC) from two sessions may be slightly higher, but the difference is minimal.

Are doubles more risky for injury?

Not inherently—in fact, splitting mileage can reduce per-run impact. The risk comes from adding too much total volume too quickly. If you're adding doubles, total weekly mileage shouldn't increase faster than normal (10% rule still applies).

What if I can only double occasionally?

Occasional doubles are fine. Many runners double on high-volume days or when schedule allows. You don't need to double every day. Even 2-3 doubles per week can meaningfully increase weekly mileage.

Running twice in one day—doubles—can boost your training. But when does it make sense? Learn when doubles help, when they hurt, and how to do them right.

Elite runners do it. Should you?

Here's the complete guide to running twice a day.

What Are Doubles?

The Definition

Doubles: Running two separate sessions in one day.

Typically structured as:

Primary run: Your main training run (easy, workout, or long run)
Secondary run: Short, easy run (20-40 minutes)

Why Runners Double

Primary reason: Add mileage without making single runs too long.

The math:

60 miles in 6 runs = 10-mile average
60 miles in 10 runs (including doubles) = 6-mile average

Shorter individual runs:

Less cumulative impact
Easier recovery
More running-specific stimulus (frequency)

Who Doubles

Typical profiles:

Elite runners (100+ miles/week)
Competitive amateurs (60-80+ miles/week)
Runners whose schedules allow two sessions

When Doubles Make Sense

Volume Threshold

General guideline: Consider doubles when single-run volume becomes limiting—usually around 50-60 miles per week.

Below 50 mpw: Usually better to build volume through longer single runs.

Above 50-60 mpw: Doubles become increasingly useful.

Time Constraints

The scenario: You have 45 minutes in the morning and 30 minutes in the evening, but not a continuous 90-minute block.

The solution: Two shorter runs can achieve what one longer run couldn't fit.

Recovery Strategy

After very hard sessions: A short easy run (6+ hours later) can promote recovery better than complete rest by increasing blood flow.

Quality Enhancement

The pattern:

AM: Quality workout (fresh legs)
PM: Short easy (recovery miles)

Separating hard effort from volume accumulation.

How to Structure Doubles

Basic Pattern

Run 1 (Primary):

Your main training run
Could be easy, long, or workout
Normal training duration

Run 2 (Secondary):

Short and easy
20-40 minutes typically
Pure volume, no quality

Timing Between Runs

Minimum separation: 4-6 hours

Allows partial recovery
Glycogen begins replenishing
Not back-to-back

Ideal separation: 8-12 hours

AM/PM split
More complete recovery

Weekly Structure Example

70-mile week with doubles:

Day	AM Run	PM Run	Total
Mon	Rest	–	0
Tue	10 mi (workout)	4 mi easy	14
Wed	8 mi easy	4 mi easy	12
Thu	10 mi (tempo)	–	10
Fri	6 mi easy	4 mi easy	10
Sat	16 mi long	–	16
Sun	8 mi easy	–	8

Total: 70 miles with only one run over 10 miles (the long run).

The Second Run Rules

Always easy. The purpose is volume, not training stimulus.

Short. 20-40 minutes is sufficient.

Flexible. If exhausted, skip it or make it even shorter.

Recovery Considerations

Increased Demands

More running = more recovery needed:

Sleep: Critical, maybe more than usual
Nutrition: Must support higher volume
Stress management: Running stress + life stress still cumulative

Sleep Priority

When doubling:

Prioritize sleep duration
Sleep quality matters more
Naps can help if available

Nutrition

Higher volume means:

More calories needed
Pre/post-run fueling matters more
Protein timing for recovery

When to Skip the Double

Listen to your body:

Excessive fatigue
Nagging aches
Poor sleep night before
High life stress

The double is bonus volume. If it compromises recovery, skip it.

Implementing Doubles

Phase 1: Introduction (2-3 weeks)

Add 1-2 doubles per week:

After easy days or light workout days
Very short (20-25 minutes)
See how you respond

Phase 2: Building (4-6 weeks)

Gradually increase:

More days with doubles
Slightly longer secondary runs
Monitor recovery carefully

Phase 3: Maintenance

Find your sustainable pattern:

How many doubles per week
Which days work best
What secondary run length suits you

Common Mistakes

1. Doubling Before Ready

The mistake: Adding doubles at 30-40 mpw.

The problem: Not enough base for frequency increase.

The fix: Build to 50+ mpw with single runs first.

2. Making Both Runs Hard

The mistake: Treating the second run as another workout.

The problem: Insufficient recovery, accumulated fatigue.

The fix: Second run is always easy. No exceptions.

3. Too Much Too Fast

The mistake: Adding 15+ miles per week via doubles immediately.

The problem: Overtraining, injury risk.

The fix: Add double mileage gradually like any volume increase.

4. Ignoring Recovery

The mistake: Same sleep, same nutrition, more running.

The problem: Under-recovery, declining performance.

The fix: Increase recovery inputs to match training demands.

5. Rigidity

The mistake: Never skipping doubles even when exhausted.

The problem: Doubles become burden, not benefit.

The fix: Doubles are optional. Skip when needed.

Alternatives to Doubles

Extended Warm-Up/Cool-Down

Instead of: Separate second run

Try: Longer warm-up or cool-down to add miles to primary run.

Easy Day Extensions

Instead of: Doubling on easy day

Try: Slightly longer single easy run.

Longer Long Runs

Instead of: Adding doubles

Try: Building long run duration first.

Who Shouldn't Double

Beginners

Running once per day provides plenty of stimulus. Focus on consistency first.

Injury-Prone Runners

If you're frequently injured at current mileage, adding doubles isn't the answer.

Time-Stressed Runners

If one run per day is already a stretch, don't add complexity.

Those Not Recovering Well

If current training leaves you constantly tired, more volume (via doubles) won't help.

Doubles are a legitimate training tool for adding volume while managing single-run stress. They're most appropriate for experienced runners at higher mileage levels. If you're ready, start conservatively, prioritize recovery, and use the second run for what it is: easy, short, supplementary volume.

Track your double runs on your dashboard.

Doubles: When and How to Run Twice a Day

Quick Hits

Key Takeaway

Frequently Asked Questions

References