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"I want to run a 2-hour half marathon, what pace should I do in my training runs?"

That’s a great question to be asking and the answer may surprise you. First the disclaimer… all training works; some just works better than others. Second disclaimer – training that works for one person may not work well for another.

Now with that out of the way, let’s get to the heart of the question. Training paces should be relative to the race you’re training for and relative to your current fitness level.

So – you’ve decided you want to do a 2 hour half marathon. The first step is to evaluate the reality of that goal. Is it appropriate for where you are NOW and how long you have to train for the race? If you’re not sure, you can use any number of online pace calculators to make a prediction based on a current race performance, or you can do some simple math and come up with a reasonable estimate. For example, knowing that a 5k race represents about 97% of your maximum aerobic performance capacity, and that a half marathon run at a RACE effort would represent about 88% of your maximum aerobic capacity you can do some simple multiplication and find out what your true target race pace would likely be based on an estimation of your current fitness. Then taking into account the potential improvement in fitness level with training you can decide whether your goal is a realistic “reach” or not.

Let’s do an example.

Let’s say you’ve recently run a 5k and you gave it everything you had – you finished in 27:11, averaging an 8:46 pace. If we assume that pace represented 97% of your maximum aerobic capacity (VO2 max) then we can estimate your fastest aerobic pace would be about 3% faster than that. An alternative method is to run a 2-mile time trial – that’s often representative of your maximum aerobic capacity. So in our example above – the 5k pace of 8:46 would be comparable to a maximum aerobic effort pace of about 8:30

Taking that 8:30 pace and projecting a race that is run at about 88% of that effort would net you a half marathon pace of about 9:36 per mile for a finish time of about 2:05. So… is a 2 hour half possible? That depends… it’s a target that’s 4% faster than your current fitness (as demonstrated by your current 5K) predicts.

How long do you have to train? How many times have you done the half marathon distance before? Have you been battling any injuries? Is your mileage base already pretty stable and strong? Is the race you’re training for on a course that’s conducive to a fast performance? Let’s assume that you have plenty of time to train (12+ weeks is nice), you’ve done the distance before, you’re currently stable in the 20+ miles per week range, and the course is truly “flat and fast”. You’ve decided that a 4% improvement is within your reach, so how fast should you run in training?

Most pace prediction tools also offer the user the critical information of how fast to run their TRAINING runs.

Remember, training is training and racing is racing. If you race your training runs, you place yourself at greater risk of injury and burnout.

Most pace tools recommend training in an aerobic range which is typically defined as something between 68% and 76% of VO2 max or to make it easier to figure – something between about 70% and 78% of 5k race pace. The slower effort (70%) is usually for longer runs.

So, let’s see what that looks like for someone who races a 5k at an 8:45 pace. Using the guidance above – that person should be doing the majority of their training runs at somewhere around an 11 to 12 min pace! Yep, you read that right… it’s significantly easier than the 9:13 RACE pace needed to achieve your 2 hour half marathon goal.

Why? Because by training in a very aerobic state, the athlete will be stimulating their body to make specific adaptations like increasing the cellular infrastructure to support an aerobic effort. Your body becomes more efficient at utilizing oxygen to produce the energy needed to fuel your muscles. This energy production process takes enzymes and transport molecules that can be stimulated to increase by training in zones that require their usage! If you do all your training at harder efforts you’ll be working in a range of intensity that may not be ideal for stimulating aerobic efficiency and at the same time this higher intensity may put you at greater risk for injury.

"But… what about that faster pace that’s needed to reach my 2-hour half marathon goal? If I always run slower, won’t I get slower?"

I didn’t say you had to do ALL your training at those aerobic easy paces… just that you did most of your training there. There is a time and place for higher intensity training! Running some of your weekly miles at faster paces is a key piece of your success as an athlete. Doing measured doses of high intensity training (interval workouts, race-pace workouts, etc) has a place in training but you would be wise to build your foundation of aerobic endurance first.

Figuring out how much of each ingredient to put in the recipe is part art and part science – your coach can help you figure it out. If you’re developing your training for yourself – then do yourself a favor and make your training efficient and effective by first evaluating your goal and then training based on CURRENT fitness while including some measured doses of higher intensity training to push your body to the fitness level needed for your goal.

Here’s to your success!  Coach Janet Hamilton, MA, RCEP, CSCS


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