What’s actually holding you back from sub-3?

For some runners, more volume can be very beneficial. For others, the main limiter is threshold fitness or raw speed. It comes down to knowing what’s holding you back. If your 5k-10k PRs are better than your marathon PR (i.e. you’re an 18 min 5k runner or faster) things that might help are more long runs with marathon paced work, a mileage increase, and/or more threshold runs.

Here are some threshold workout examples:

• 2 x 3 miles (2-3 min easy) at threshold pace (~6:42-6:34 min/mile, 4:10-4:05min/km)

• 10-12 x 3 min (1 min easy) at ~4-8s faster than threshold pace

• 2miles -2 miles -2 miles -1 mile (2-3 min easy) at threshold pace, or do a progression starting a little over threshold pace and ending the mile a little under.

However, before you start marathon training or in the first phase of training for a marathon, you’ll want to focus on faster, shorter workouts. This could be everything from 12 second to 1 minute hill reps, to 200s, and 3-4 min intervals at VO2 max pace. Then even as you get more into marathon specific training, you can still add in more touches of speed without running yourself into the ground.

These are some specific ideas:

• 8 x 30s (1 min easy) or 5-6 x 1 min fast (1 min easy) after the end of a threshold run

• 10 x 800m (1-1.5 min easy) at ~10k pace

But what if you’re already in your final 8 weeks of marathon training?

If you’re in your final 8 weeks, the goal shifts. You’re not trying to close the gap, you’re building fitness and getting comfortable at sub-3 pace.This could look like 4 x 3-4 miles at current marathon fitness pace builds the endurance and strength to hold your pace on race day. Or, 10 x 1 mile at 6:52/mi (4:16/km) gets you touches of sub-3 pace in your long runs without overdoing it, while still supporting your current marathon fitness.

Zone 2 training has become one of the most discussed concepts in endurance running, and for good reason. Easy aerobic running is foundational.

But when runners say, “I trained in Zone 2 for a year and didn’t improve,” the issue is rarely a lack of patience or discipline. It’s usually a misunderstanding of how Zone 2 fits into the larger training picture.

Easy running supports aerobic development and plays an important role in building tissue resilience and durability. It allows adaptations to accumulate through repeatable, recoverable training.

For many runners, “Zone 2” aligns with easy, conversational running. But for higher-level athletes, spending too much time near the top of that range can quietly turn easy days into moderate ones and interfere with recovery.

What easy running does not do particularly well on its own is prepare you for the demands of racing.

Race performance depends on more than aerobic capacity. It requires efficiency at faster speeds, tolerance for higher metabolic stress, and the ability to coordinate force under fatigue. Those qualities are trained through targeted exposure to higher intensities.

That doesn’t mean hard workouts year round. It means that at some point in a training cycle, most runners benefit from introducing small, intentional doses of faster running. This can include strides, tempo or threshold work, and occasional VO₂max efforts. Each serves a different purpose, and together they complement the foundation built by easy mileage.

Easy miles make harder training possible.

Harder training makes fitness specific.

Where easy running matters most is when you’re building the ability to train.

If you’re newer to running, returning from time off, or rebuilding mileage, keeping most runs easy while gradually increasing volume is exactly the right focus. At this stage, easy running strengthens muscles and connective tissue, improves coordination, and raises tolerance for frequency and consistency.

But when weekly mileage is very low, easy running alone may not provide enough total stimulus to drive meaningful performance improvements, particularly for longer events like the half marathon and above. In those cases, progress often comes from a combination of consistency, gradual volume increases, and complementary stress such as short intensity work, strength training, or cross training.

The goal isn’t to rush fitness. It’s to expand what your body can handle sustainably.

The real value of Zone 2 isn’t that it’s a special or optimal pace. It’s that it allows you to train more, more often, without breaking down. By keeping mechanical, metabolic, and nervous system stress low, easy running makes recovery and repeatability possible.

That consistency is where long term fitness compounds.

As weekly volume becomes more sustainable, easy mileage creates room for quality work to actually do its job. Zone 2 isn’t about chasing a number or a philosophy. It’s about building training you can repeat week after week.