A Journey towards a Sub 2 Hrs Half-Marathon

Chim Himidumage
5 min readMay 11, 2021
Photo : Cropped from https://www.flickr.com/photos/chuddlesworth


Eighteen months ago, I could barely run 3kms with confidence. However, once in a while, I managed to extend it up to 6kms after putting in so much effort. Not to mention that I had to get out of my comfort zone completely for that. Then I came across two running communities called Colombo City Running (CCR) & Colombo Night Run (CNR) who organize weekly runs. After connecting with them, I got the opportunity to run with a group of people, where the distance can be chosen according to the preference of 5Km, 10Km, or more.

Running with a group of people helped me to take a big leap in the distance Sooner, I started to run longer distances conquering my initial range and managed to run 10–15Kms, in a very short period.


In July 2020, I managed to run a half marathon (HM) and it took me 2hours and 26 minutes. The only training I had a couple of weeks before the HM was a long run of 18Kms and then tapering the distance until the race day. Again in February 2021, I ran half a marathon and managed to finish it by 2 hours and 12 minutes. In both these races, I realized that I have a lot of energy left in my system at the end of the race. It led me to the realization that I’m not running with my optimum speeds over 21.1Kms.

Splits of the run in February 2021 (2h12m07s)

Identifying The Best Tools

I shared my running stats with David Ostwald, whom I knew believes a lot in numbers and follows more systematic training for running. He directed me to two fantastic tools, and those tools entirely changed how I run. Tools are “Jack Daniels’ VDOT Running Calculator” and “Run Coach”.

The Process of Using Tools

For the benefit of anyone who wants to use these tools, the following are the high-level steps I followed to use these tools.

Based on a run you have done recently (which you have given your full effort), Jack Daniels’ VDOT Running Calculator predicts your timing for various distances like 5Km, 10Km, Half Marathon, Full Marathon, etc. Further, it gives you a set of important numbers like your easy run pace, threshold pace, etc., which provides you with a much better understanding of your capabilities as a runner.

In the light of this knowledge, you could use Run Coach to plan your training for the next race. Run Coach provides the ability to set your race date and a goal completion time. Similar to Jack Daniels’ VDOT Running Calculator, Run Coach uses stats of a recent run to predict the ending time for your future race. You can set the plan of action in Run Coach and include the days of the week you run, days you prefer doing long runs, and speed sessions. Apart from these, you can further set up other activities such as strengthening, swimming, or Yoga. Run Coach uses these inputs to compile a personalized schedule and train you for the race on the given date for the goal/estimated completion time.

Before using these tools, I had to decide the following factors by myself

  • The distance and the pace for each long run
  • Structure (paces, durations, distances) for a speed session
  • Point to start tapering before a race
  • Running distances for tapering

The numbers were fabricated without any basis, and hence I believe I messed them up and ended up hindering my performance rather than improving it.

The Accomplishment

Jack Daniels’ VDOT Running Calculator and Run Coach gave me all the necessary details to train effectively. Following the schedule provided by Run Coach, I realized that I’m running strong, and my health tracking device confirmed it with solid evidence.

The Above figure shows how my VOMax changed over time. I started following the Run Coach at the end of February and my VOMax was at 48, and you can see how the training pushed up my VOMax to 51 as I reached race day.

As the race day approached, I had doubts in my mind about running a Half Marathon in less than 2 hours. I knew I could run faster than in February, but had only limited confidence in shaving off 12 minutes from my personal best. In the meantime, David Ostwald suggested a pace plan for the race. I trusted his experience in years of running and also his suggestions looked very much logical to me. Hence we decided to stick to it.

I followed Run Coach’s pre-run routine on the race day and then executed the plan accordingly. Being a great partner, David ran next to me the entire distance and I managed to finish my Half Marathon in 1h 56m 35s, which is a personal best by 15m 30s. I felt very much accomplished and ended up appreciating the benefits of a noncompetitive sport like long-distance running even more.

Splits of the run in May 2021 (1h56m35s)


The entire process, which includes the long-distance run, training sessions, and the HM, would not have been possible without the generous support from a few people around me. Special thanks go to my family for tolerating my absence at home during training sessions. Also, I sincerely appreciate and thankful for David Ostwald who guided me for systematic training, trained with me over the last few months, and ran next to me the full distance to achieve my best timing. Last but not least, I thank my fellow runners and admin group CCR/CNR for building an open platform that brings runners together and supporting each other.


Long-distance running is a great way to keep you healthy, and its noncompetitive nature has many other social benefits. If you wish to run regularly and run without causing any injuries, it is essential to have an excellent understanding of your performance levels and threshold paces. If you are trying to improve your running (run longer and/or run faster), it is essential to follow a systematic training schedule. This avails you by providing vital details like the distances and the pace you should carry for each run while training. The tools further bring forth other personalized parameters like easy pace, threshold pace, etc.