21KM to Miles | How to Run a Faster Half Marathon

Are you wondering what is 21km to miles? If so, I am glad you have made it here to RunDreamAchieve. The fact that you are searching for this answer tells me more than like you are an athlete. Perhaps, preparing for or seeking to run a faster half marathon time. My aim with this post is to share with you some strategies to run faster. Also, to discuss what 21km to miles comes out to.

The half-marathon is a highly aerobic event. Remember, the faster the race the more oxygen is required (anaerobic). Also, the slower the race the less oxygen demand there is on the body. That being said, you still need speed work and to develop your overall leg speed for a half marathon. Pace sustainment is one of the biggest challenges for most runners.

We all can hold goal half marathon race pace for a number of miles or kilometers. It is something entirely different to sustain for the entire duration of the race. 21km to miles comes out to 13 miles. It is just shy of the half marathon distance which is 21.1 kilometers.

How Many Miles is 1/2 Marathon

As mentioned above, a half-marathon comes out to 13.1 miles. 21 kilometers is just shy of this being 13 miles in length being 13.0488 miles to be exact. I would focus first on building your aerobic base before starting specific half marathon training. The reason is you will lessen your likelihood of getting injured. In addition, you will be strengthen your body to handle faster, anaerobic workouts.

The optimal time frame to train for a 21 kilometer race is 16 to 24 weeks in duration. I always tell the athletes that I mentor here to focus on a longer build up. One, you will not be in a rush to get into great shape. Two, you will allot sufficient time for your body to adapt to the harder training you will be experiencing. Lastly, you will improve your body’s lactate tolerance effectively.

It is very difficult to prepare for a half marathon in the span of 4 to 8 weeks. Of course, there are some runners who can manage it. So, focus on quality rather than just quantity and your chances of success will rise. I would also start implementing strides into your routine twice per week. Strides are short, 50 to 100-meter acceleration drills. You can improve your form and leg turnover by doing these regularly.

What is One Kilometer?

One kilometers comes out 1,000 meters or the equivalent of 2 and half laps around the track. 10,000 meters is equivalent to running 25 laps around the track. Of course, if you are crazy enough to run 21 kilometers around the track it would be over 50 laps. 21km to miles is 9.3 miles or 21,000 meters in length. The runners who are running the best times are running more quality mileage.

In fact, the world’s top runners are running between 35 to 40% of their weekly mileage at or below their lactate threshold. Remember, we are running between 85 to 89% of our max heart rate at this effort. So, this is high quality running. I would highly recommend investing in a heart rate monitor. I regularly use the Garmin 245 myself. It helps me to ensure that I am not over training.

Also, that I am not running too fast on my recovery days. I also use it to stay at the proper heart rate zones during my tempo runs and long runs. So, to run a faster half-marathon you have to be strategic in how you set up your training. I have half marathon training plans here that range in duration from 8 to 24 weeks in length. 24 weeks is the most optimal. Again, you will be allotting sufficient time to adequately adapt to the hard training you will be doing.

How Far is 21 KM in Minutes

How fast you cover the 21 kilometer or 21.1 kilometer event will depend on your aerobic and anaerobic fitness. The world record for the half marathon is a staggering 57 minutes and 31 seconds set by Ugandan Jacob Kiplimo on 21 November 2021. Kiplimo held 4:23 per mile for 13.1 miles or 2:43 per kilometer for 21.1 kilometers.

The world record for females is 1:02:52 ran by Letesenbet Gidey on 24 October 2021. Gidey held 4:47 per mile for 13.1 miles or 2:58 per kilometer for 21.1 kilometers.

Of course, these are the very best times ever run by a man or woman. So, be sure not to compare yourself to these runners. That being said, it proves what the human body is capable of.

So, how far is 21km in minutes? It will largely depend on the quality of training. The average time for 21km run is around 1:55 for males and 2:11:57 for females. Again, times will vary depending on the maturity level of the runner. There will be some runners who are aiming to break a 2 hour half marathon and others, sub-1:10.

How Much is 21 KM in Hours?

The pace you sustain for this race distance comes down to how much speed work you are doing. As mentioned above, there are runners who have broken 58 minutes for the 21km event. We now have females running under 1 hour and 3 minutes for the distance. So, the human body’s ability to handle high levels of lactic acid build up is staggering. Remember, 21km to miles is 9.3 miles of 21,000 meters in length.

Again, it just depends on the quality work you are doing. Remember, it takes the body between 21 days to 4 weeks to adapt to any stress load being placed on it. So, be patient during your training build up. The good news is the body always adapts if there is sufficient rest in between each hard stimulus.

How far has your tempo runs been in the past for your half marathon races? I ask that because many runners are still not spending sufficient time training at their anaerobic threshold. Remember, this is running between 85 to 89% of our max heart rate. I would recommend working to extend your tempo runs out to between 8 to 10 miles (16km) for this event.

What is a Good Time for a 21KM Run

I think a good time is anything under 2 hours. The athlete will need to sustain 9:09 per mile for 13.1 miles or 5:41 per kilometer for 21.1 km to run 1:59:59. I also created a resourced called the Sub 2 Hour Half Marathon Domination course to help runners break this barrier. I go in-depth on each specific area the runner must improve upon to run under 2 hours for the half marathon in the course.

Of course, a good time will vary from athlete to athlete. There are some athletes who think breaking an hour and 30 minutes is a good time. The main focus is to train to master your own specific goal race pace. You may not be seeking to run 6:52 mile or 4:16 per kilometer pace to run 1:29:59. Perhaps, you are aiming to break a 3 hour half marathon.

We all have differing goals. So, spend a higher percentage of your weekly volume at or below your goal race pace. Remember, quality over quantity. Higher mileage is no guarantee that you will run a faster 21km race. 21km to miles is 13.1 miles. So, you will most certainly need to run easy as well as fast in order to achieve a faster race time.

Faster, Varied Paced Long Runs

Are you running long and slow every single weekend? There are many runners who are still running too slow during the week. Yes, easy running is still vital for running success. That being said, if you run too slow, too often it will only make you a superior long, slow runner. I am sure you have a goal time you are aiming for, for your half marathon.

So, start running your long runs faster. Of course, you should not be running fast every single weekend. Again, recovery is vital in order to adapt to the hard workouts. Below is an example of a faster, varied paced long run I was doing prior to running 1:07:06 for the half marathon. I was also able to lower my marathon best from 2:43:36 to 2:19:35 using this tactic.

  • 2 mile jog, 6 miles@5:35 mile pace, 2 miles easy, 1 mile in 4:55, 5 miles@6:05 mile pace, 2 miles easy, 1 mile in 5:00, 2 mile cool-down jog (21 miles)

No, you don’t have to do 21 mile long runs to run a fast 21km race. I think the optimal distance is between 14 to 16 miles for the half-marathon. I would always run my following week’s long run between 8 to 9-minute mile pace. Again, recovery is essential. So, make sure you are jogging during your easy days.

Develop Your Leg Speed

21km to miles is 9.3 miles or 21,000 meters. So, to cover this distance fast you need to work on your leg speed. Our goal is to recruit more fast twitch muscle fibers. The more of these we can recruit the more effective and efficient we will race.

I would recommend doing at least 1, vo2 max workout per week. Examples of vo2 max workouts are hill repetitions, road or track intervals or fartlek run workouts.

We run at or around 95 to 100% of our max heart rate at this intensity. So, you will be challenged at this intensity. That being said, running this fast will help to make your goal half marathon race pace feel easier. Also, you will slow down far less than your competition if done correctly.

Closing Thoughts

My last recommendation is to not neglect mental training. The world’s top runners pay attention to mental rehearsal. They know that mental preparation is equally as important as physical preparation. The good news is that it doesn’t take more than 10 minutes per day to do this. You can visualize success at anytime of the day. The best time is right before you go to bed at night or when you get up in the morning.

So, see yourself crossing the finish line in your goal 21km time. Also, running relaxed, passing people and confident. Be sure to subscribe to the RunDreamAchieve YouTube channel. I focus on making new content there each week to help runners like you set new personal bests. I look forward to hearing about your new personal bests from the 800m to 50k ultra marathon distances.

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