Wong Ho Chung answers your HK4TUC & COROS Questions

Posted on February 16 2022

Wong Ho Chung answers your HK4TUC & COROS Questions

It’s stuff of legends, Chung Sir finished the #HK4TUC in 46hr55. The magnificent Wong Ho Chung did what was once thought impossible, and even then, only 6 days after running a sub 11 hours HK100.

What is also amazing was that his COROS Vertix 2 still had 72% battery life after 46 hours without recharging it once during the event.

We are honoured to have Chung Sir visit us merely a week after this accomplishment to share his experience as a COROS user and the fastest finisher of the Hong Kong 4 Trail Ultra Challenge: 

 Cover photo, courtesy of Lucien Chan

Q:  Gone Running 

A: THE Wong Ho Chung, "Chung Sir".


Ultra Trail Mont Blanc (UTMB) 11th overall, Aug 2021.  photo: Wong Ho Chung Sportsman FB


Q: First question from Jenny “You did 3weeks of quarantine after UTMB….What kind of exercise did you manage to do in your hotel room which you think was helpful to stay in condition”

 A: “I did manage to borrow a treadmill, but it was no fun TBH.

You probably did not see it but I did have a significant drop on my physique at the end of the quarantine. Took almost two months of progressive training afterwards to reverse that effect.”



Vibram Hong Kong 100 Flex 2022.  photo: Wong Ho Chung Sportsman FB

Q:  You ran a brisk 100km only 6 days before the 4TUC, why, and how did you recover?

 A: “I am quite familiar with my own recovery process and physical limit after the [4 Deserts Grand Slam] (2018) and [UTMB] (2019, 2021).  Frankly there was no training programme targeted to the [HK4TUC] (298km, 2 Feb), I did a recce back in summer, and since then I had been focusing on being fast for the [UTMB] and [Vibram HK100], for which a lot of high intensity running was required.  “

(Editor: a timeline for Chung’s more significant runs leading towards the [HK4TUC]:
  • 14 Jan 2022 – [HK100 Half] 54km 4h52
  • 22 Jan 2022 – [HK100] 94km 11h56 supporter for Angie Yan
  • 26 Jan 2022 – [HK100] 100km 10h56
  • 02 Feb 2022 – [HK4TUC] 298km 46h55 )

“My original plan for the [HK100] – 100km was on 15 Jan, immediately after the 50km version of the same virtual race (14 Jan), unfortunately my speed muscles did not show up until 26 Jan, hence the close 6-day gap between the 100km and the 298km you see.

I have always followed a rule while planning:  speed work, then rest, then a longer distance, then rest, then a really-long-distance challenge such as the [4TUC].  In my humble opinions this flow is safer than the other way round where you do a long distance followed by a brisk race, which increases the chance of injury.

There certainly would have been a longer rest between the 100km and the 298km if I could have my legs ready for that former run earlier, but circumstances are never perfect. 

On that 6 rest days I was really focusing on getting my legs back by stretching, massaging, jogging and on nutrition. They were indeed heavy when we set off for the [4TUC], but this challenge is an endurance event, speed was nowhere as important as being steady, long-lasting and mentally strong.  Once the body warmed up the fatigue was gone. In fact I was happy I did not have a much longer rest because then my endurance would have dropped. “



Q:  What was the target that you set for the [4TUC]?

 A: “Being the first time doing this challenge, I had no faith of predicting my own results. 

In fact, I already wanted to do it last year (chuckle), there were Jacky, Stone, Salomon and many hardcore second-time runners aiming to break 50hrs, I did not have that confidence being able to do so, not without their know-how.

Coming to this year, having seen that it is indeed possible to break 50hrs, I made 2 plans to my support buddy, Stone – a 50hr and a 60hr plan, both had similar running times but the longer one involved couple of hour sleeps between each trail. 

It was impossible to imagine how my legs and my mental strength would be after 200km, fortunately I did run better than expected, thanks to the numerous challenges over the years.  Some said doing a distance this long for the first time is hard to get it right, I believe I have proved that enough experience could make an exception, but it is certainly true that there’re many other ways to improve it if I was to do it for a second time.”


HK4TUC, Wilson Trail, from Lam Tin to Tai Koo by public transport as per the rules.  Photo by Lucien Chen

Q:  For 4TUC, did you worry about stomach issue for this distance that you have never done?

 A: “It did raise some concern TBH, over the years training my nutrition intake, I have discovered that in lower intensity workouts I really don’t eat a lot.  But would that be the same after 3 or 4 trails?

Like usual, I started off the [4TUC] well fed and loo checked, I knew the MacLehose Trail pretty well from the previous FKT (Fastest Known Time) challenges, I did not need much on this trail, had a couple of stops for the water fountains and vending machines for soy and chocolate milk, that was a smooth 100km. 

Lovely wife Viann bought me a portion of fried rice between the Mac and the Wilson Trail, as usual, I never waste food (chuckle), I finished it and set off for the Wilson that again not much food was needed on.  I did, however, planned to replenish at Lam Tin, but I was in a rush and a little nervous, so instead of the plenty of good things that I fancied, I only picked up a Po Lo Bao (pineapple-shaped bun) instead, not entirely suitable eh!! (Chuckle hard!) "

 HK4TUC, Wilson Trail, Lam Tin self-supported Pineapple-shape bun hunting.  Photo by Lucien Chen.

"Before the start if the HK Trail my wife gave me another fried rice, and I picked up a bottle of sports drink at the gas station before heading onto Black’s Link.  I was in such a rush for an earlier ferry I didn’t make other stops.

When I finally made it to Central Pier, Stone, there supporting, gave me a Fujian fried rice, which is nice with the sauce and filled me up again nicely. "

HK4TUC, from Hong Kong Trail to Lantau Trail, supported by another legend, Stone Tsang.  Photo by ViolanAlan

"Then it came to the Lantau Trail and my problem arose. It has never been a problem with indigestion for me, but this time I had stuffed myself with 3 large portions of fried rice without letting them out through the other end, I was unable to eat more and was feeling a little nauseous, attempts to induce a puke was of no avail.

There was another complication in Lantau as there was no replenishment, all the stores were closed as I was running from 8pm to 8am.  I was carrying some sports gels along but had to get tap water from the WC to continue my journey.

With these setbacks, I merely ate on Lantau Trail.  They made up a very good lesson for the future.

It was nice that this 298km was a personal challenge instead of a race which mean it is less pressing, allowing us time and flexibility to communicate with our crews telling them exactly what could help.

At the end of the 298km, my watch told me that I spent more than 23000 Kcal in this journey.  Which is insane, given that a man of my size generally spends around 10% of this figure in one day. “


HK4TUC, Finished, 298km, 14,500m+ and 46hr55mins later.  Photo by Lucien Chan


Q: How do you feel since the finish of the challenge about 10 days ago?

 A: “Constantly hungry!

My muscles were not physically drained in this challenge, I felt like I could have kelp going, but my psyche, my will power and my spirit had run dry.  Over the last few days, not only that I am constantly craving for food, I would also doze off anytime, which never happened before. “


COROS app record says it all.  Fatique index 4736, 23,456kcal burnt, 14,874m elevation gain! 


Q:  So, what did you want to eat at the end of the 298km?

A: “French fries!

I had had enough rice or sports nutrition by then.  It would have been so good to have some hot French fries with salt then and there!!”



HK4TUC, Wilson Trail, from Lam Tin to Tai Koo.  COROS Vertix 2 on the left wrist and COROS Apex Pro on the right.  Photo by Lucien Chen

Q: Question from Moran: “Have you ran with 2 Coros watches by any chance?”

A: “Yes I did, on purpose.

First I thought it would look rather cool and astonishing to have the entire course mapped out on one recording (Editor:  Hell YAHH!) , and that was done by my COROS Vertix 2.  My COROS Apex Pro as a second watch was needed to record the routes individually so there would be reference records for myself and fellow challengers in the future." 

Strava record of Chung Sir's HK4TUC, by COROS Vertix 2.

"When I planned for this run, there wasn’t much data I could study because this event is so unique that none of us have run it times enough to be able to explain the key dos and don’ts for the others.  I wanted to create something for our future selves.”



Q:  Question from Jcy: “Did you use the map to track the route on this particular Coros?

A: “I totally needed two watches to do this challenge, the navigation was super important. 

Although we were running on the four major trails, but a lot of junctions had to be remembered. I had little knowledge of the HK and Lantau Trails, even parts of the Wilson Trails, navigation became quintessential in the second evening, around the Lantau Ling Wui Shan area. It was 42hrs into the race, my mind was tired, it was so foggy that I hardly saw my own two feet, not to mention any sense of direction.  The COROS Vertix 2 I wore on one wrist measured the entire journey, recorded all the figures etc.  The COROS Apex Pro that I was wearing on the other wrist was there to measure individual trails and navigate. That navigation helped tremendously as I could not afford to get lost.  It wasn’t until Shum Wat / Ngong Ping that I knew the ways.  The watch navigation certainly made a critical different.”


 May be an image of digital watch

Q: “You had 72% battery left after the whole 46hr55 run, did you use special power safe mode? Or do you have a preferred satellite setting you use in Hong Kong? “

A: “The COROS Vertix 2 I was wearing supports several GPS settings, I have tried 3 of those. 

Weeks ago I tested the “Dual Frequency” satellite communication, which made locating super precise and the battery would last for about 50hrs.  I then tried the “All Systems On” mode at which the watch could use all 5 satellite systems and the battery would last for about 90hrs. 

At last I switched it back to the factory default Standard GPS Mode, which I found accurate enough on the [HK100] (11hrs, 94% battery left), and settled at this setting for the [4TUC].  After 46hr55 continuous GPS recording, the watch had 72% battery left.”



Q: “You ran 5m19/km GAP on the 2nd kilometer of the HK4TUC, and then you ran a same pace (5m20/km) after 297km, going into Mui Wo. How did you do that?

A: “I did experience some low time in the challenge, especially the last 12km.  I was totally out of form on my way up to Sunset Peak, there were hallucinations everywhere.  I jogged up to the summit to wake myself up.  Thanks to the craving for fellow human being and the joy of accomplishing this, I pick up the speed as soon as I saw Mui Wo from afar and I managed to rush down putting the drowse and fatigue behind. “


May be an image of 3 people and indoor

HK4TUC Finish at Mui Wo, a kiss on the green postbox and a champagne shower being the only prize of this magnificent event.  Photo by William Leung.


Q: What was your “fatigue” figure according to COROS at the end of the [4TUC] and the watch suggested you to rest for how long?

A: “The guideline said a figure about 216 means you needed a rest, but then my figure was more than 4736, about 20 times over the advised limited, that was a little extreme (chuckle, chuckle bashfully).



HK4TUC Finish, Mui Wo, Chung's loving wife Viann and their lovely family.  Viann has always been there for Chung's accomplishments,  Photo by Lucien Chan.

Q:  Have you considered training your beloved wife to do [4TUC] and you be her supporter?

A: “This is a funny question, hahaha!  This event is extremely painful and mad, this might be too extreme for my wife.  For the sake of Viann’s health and safety, I wouldn’t recommend it, but I do encourage her to exercise and train. “

#relationshipgoal!  Photo by Lucien Chan.

Photos thanks to ViolanAlan, Lucien Chan, William Leung, Chung Sir, Asia Pacific Adventure.

To watch the the interview in video (Cantonese): 

At the end of this interview, Gone Running would like to sincerely thank Andre & Paper for the 4TUC event, and the many support crew + photographers along the way, you guys allow these runners to shine.

And again, our greatest respect for each 4TUC runner that was so brave to show up at the end of Mac on that cold, wet miserable morning.  May you all be recovering very quickly and get some bodyfat!

Take care and happy running!



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