The Greatest Distance Run On A Treadmill in 12 Hours: Ronnie Delzer vs. The Guinness World Record

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The Greatest Distance Run On A Treadmill in 12 Hours: Ronnie Delzer vs. The Guinness World Record

Blog by Ronnie Delzer, Sponsored Ultrarunner

I started running before I could walk … well, not really – but I’ve been running for as long as I can remember, since around the age of 3. I’ve always found joy in running; it allows me the chance to free my mind and let go of whatever stress I may be dealing with. I like working hard towards achieving goals and getting results. I enjoy pushing my body beyond its limits and I’m amazed at what the body can endure when the mind is determined to achieve.

I was fortunate enough to run collegiately for four years at East Carolina University. After college, I completed the Myrtle Beach and Boston marathons in 2006. The next year, I got the triathlon bug and found myself doing Ironmans off and on for about five years. I’ve always had a passion for endurance sports because it’s where I’ve been able to excel. In the spring of 2013 I did a 15-mile obstacle course race, the Warrior Dash, and won by a pretty good margin. I found myself at peace during the trail sections of that race and it brought back good memories from my college cross-country days. After that, I ran a 50K trail race in December and ended up winning by a good margin. A month later, I had a totally different experience on a very tough day. After a few months off, I decided to train for a 100-miler towards the end of the year. I completed the Rocky Raccoon 100 mile in 14:15:53 and placed third in the US 100mi Trail Championship race. I continue to look forward to wherever my passion for running leads me.

The following is a recap of Ronnie’s Guinness World Record breaking Greatest Run On A Treadmill in 12 Hours. Training for and recovering from an event of this distance is a tall order; however, many of the tips, techniques and strategies that Ronnie shares can be applied to any athlete at any distance. Here’s how it went down.

My quest to attempt to break the Guinness World Record for longest distance run on a treadmill in 12 hours began in April. That month I didn’t get the result I needed at a race for an automatic qualifier into Western States. Approaching summer and not having any races on the schedule, I decided this was the right time to go for the treadmill record. The current record is 84 miles, with a pending record of 86.49 miles. It was mid-July when I received confirmation from GWR that my application had been accepted. After a tough first half of summer during which I had I really struggled with the Texas heat, I was newly motivated by the notification, and I immediately began planning with my coach, Ian Sharman.

We figured six weeks was sufficient time to be prepared. I was running 20 miles on a treadmill within a few days and went from running 50 miles a week to 70+ in a few weeks. I spent most of the treadmill runs reading and familiarizing myself with all the rules required for the attempt, as well as watching ultra-running related (pre- and post-Western States interviews) videos. I found out early on not to focus on the time; otherwise, a couple minutes felt like eternity. I did shorter, higher-quality workouts on the road and longer workouts on the treadmill. Running on a treadmill is so repetitive that we had to be careful not to do too much and end up getting injured. My longest treadmill run was 30 miles and consisted of six sets of three miles easy and two miles at marathon effort. It gave me a chance to change pace and figure out what was comfortable on the easy miles. After discovering that my easy recovery pace was faster than the current record pace, I began to gain confidence with these types of workouts. I also dialed in on nutrition and hydration needs and what my sweat rate was like running indoors. Everything was shaping up nicely and I had a two-week taper going into the GWR event.

The event took place on August 20th at Luke’s Locker, a local running store in The Woodlands, Texas (outside of Houston). It was the perfect venue, as it was well equipped and open to the public. My goal was 90 miles in 12 hours, a 7:50 pace with up to 15 minutes for breaks. I started the day with a banana, at least 12 ounces of water mixed with Klean Athlete BCAA, and 12 ounces of beet juice. I also had a bottle of Alkaline 88 water and a bottle of Tailwind, which I sipped on as needed during the run. Every hour I took a few Klean ELECTROLYTES pills and also had a Huma energy gel every half-hour, or more as needed. At the end of one session, I felt like I may have taken in too many calories and was little bloated, but I’d much rather experience that than not having enough. My fluids, energy gels, and electrolytes gave me enough fuel to keep going strong. I had to go into the zone and dig deep a few times when things got uncomfortable, but I always made sure I didn’t skip on nutrition. Overall I feel like I nailed my nutrition plan and as a result felt in control the entire time.



I was comfortable running faster than a 7:50 pace early, so that was part of my strategy at the beginning. I got into a nice rhythm and knocked out 45 miles at a 7:19 pace, which made it nice to have some flexibility to slow down later if needed. We had some unexpected challenges early on with the treadmill, which led to more breaks than I planned, but it wasn’t ever an issue at the pace I was running. The more frequent breaks allowed me a chance to do some foam rolling every hour to keep my glutes, hamstrings, and hip flexors happy, and also use the restroom to make sure I was hydrated enough. I stayed calm and interacted with the crowd (which got rowdy and fun towards the end).

My chiropractor and I had planned for him to do some adjustments at about halfway through. It was a relief to get my body realigned and do some Active Release (ART) on my hamstrings and glutes so I could maintain an efficient running stride. That was the key to me holding onto a quicker pace, and I ran the next 35 miles at a 7:30 clip. Without those breaks and attention to my body, I don’t know if I could have kept up that pace without experiencing a lot of discomfort. The pain started to settle in and my pace began to fade at 9-1/2 hours. My knees and feet were beginning to hurt from the repetitive pounding, but I pushed through the pain, boosted by the crowd’s support. The energy in that place was crazy and definitely kept me going and mentally entertained. I broke the record with about 24 minutes to spare, got off at the next mile mark (87) and went out into the crowd to celebrate for a brief moment. At that point it wasn’t about running 90 miles; it became more about enjoying the whole experience with everyone there who had supported me the weeks leading up to the event. I added a couple more miles and finished the day a little shy of 90, unofficially 89.38 miles.

The next day I got out of bed and immediately into compression boots to increase blood flow and help reduce swelling. I repeated that a few times throughout the day and it made a big difference for me to move around without a lot of stiffness. My muscles were a little tender, but my knees and feet hurt the most. I refueled with Klean RECOVERY a couple times throughout the day, and ate primarily anti-inflammatory foods. I didn’t sleep well that night with my body was out of whack, so I took a few naps during the day and caught up on rest. I finished the day as I always do by taking my arsenal of Klean supplements; Multivitamin, Omega, Vitamin D, Antioxidant, Cognitive, and Probiotic. Thanks to Klean for delivering products that are so stringently tested for quality and don’t contain any substances that shouldn’t be in there.



Usually, two days after a tough race I’m really sore, but I’m happy to report that after an effective visit from my chiropractor, including TENS treatment and Cold Laser therapy, I’m getting around much better than expected. Recovery isn’t over, so I will continue to listen to my body and gradually get back into training after I get the rest my body needs.



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