You’re halfway through a trail race and you come up to a moderately steep hill. You start ‘running’ only to find yourself in lockstep with someone hiking. Maybe you start hiking and get passed by a runner seemingly floating up the hill. Sound familiar? We have all experienced this phenomenon at some point during our own racing or training endeavors. Suddenly left questioning whether we should be running or hiking, whether we are fit enough, tough enough, or somewhere in between. The good news is, even the experts can’t definitively tell you whether hiking or running is most economical in all scenarios, but there has been enough momentum in this field over the past decade to start to paint a better picture.
Back in 2016, I was lucky enough to find myself in Boulder, CO working alongside Dr. Rodger Kram (professor emeritus and one of the most sought after biomechanists of our generation) Mandy Ortiz (Mountain Running Junior World Champion), and Nicola Giovanelli (now Dr. Giovanelli,one of the renowned experts in the space of trail running energetics and performance). I was assisting on a project that aimed to study walking and running at extremely steep slopes to determine if there was a slope or speed where walking was more advantageous than running (8). This was one of the first studies aimed at trail running, specifically studying inclines and speeds like those achieved during a vertical kilometer race. I was stoked to say the least!
Historically, scientific research on trail-running is still lacking, but since 2016 there has been more research done examining the questions posed above. What that means for us is that we can now form evidence-based recommendations on how to move through the mountains more efficiently including; optimal uphill hiking and running techniques and the use of trekking poles for moving both up and downhill.
Some background on locomotion
Let’s start with the basics. When it comes to locomotion, walking typically requires less energy than running at speeds slower than 2m/s (or about 13:25 minutes per mile) (3) and can be distinguished by a lack of flight phase. This means that at any given time, one foot is always on the ground. Running is typically more economical at higher speeds because your tendons are extremely efficient and have the ability to act like springs – storing and releasing energy. Whereas, walking is more similar to a pendulum motion (5). Running typically can be visually distinguished from walking by looking for a flight phase, or a time when both limbs are off the ground, however if you run at a slow enough speed, the flight phase can go away (8). This is called ‘grounded running ‘(8). Typically people will transition naturally from walking to running at a metabolically optimal speed (around 2 m/s or 13:40 min/mile), but this speed can vary based on body size (10).
We’ve all felt this transition phase. Imagine you are on a treadmill slowly increasing the speed until you start to run? How weird does that speed feel right before you start to run? How much worse would it feel to try to walk a little bit faster than where you started running? A lot worse. It doesn’t feel right, and it is more taxing metabolically, so we naturally stay away from it. i.e. we all naturally gravitate to our most efficient form of movement.
Should I run or hike?
Trail-running brings in an interesting set of parameters that impact the energy required to move over trails. The energy demands of running and walking go up as we move on softer surfaces, uneven terrain, and uphill (12,16,33). Several past studies investigated walking and running at steep inclines up to 45% or roughly 25 degrees (12). Minetti, et al, found that at the steepest inclines, walking and running at self-selected speeds become very costly (12). To account for the more extreme environments of trail-running, in 2015, I assisted Nicola as he studied mountain runners on slopes between 9.4 degrees (~15%) and 39.2 degrees (almost 100%!) (8). The treadmill was so steep that we had to put skateboard tread on it to make sure our athletes wouldn’t slip off! The vertical speed stayed constant, and participants had to run and walk at the same vertical speed at all incline levels. In this study, running uphill at 9.4 degrees at a speed 2.1m/s was energetically more efficient because it was too fast of a speed to walk efficiently, and was therefore, more costly (8). However, at all other inclines at or above 15.8 degrees, it was over 8% more efficient for athletes to walk (for reference, the Nike Vaporfly improves efficiency by ~4%) (8). Walking conserved a lot of energy compared to running the same speed at these extreme slopes. One explanation for this could be that at these steep grades, even though participants were instructed to ‘run’, one foot was always on the ground like walking but at a faster frequency and shorter stride length than walking, they were grounded(8). The typical mechanics associated with running and walking do not hold true when moving uphill. ‘Running’ at very steep inclines does not have a flight phase that is typical of traditional running gait on flat ground. This means the ‘spring’ isn’t getting loaded like it does during flat running, and it is not an efficient means of locomotion.
In general, hiking is recommended at slopes greater than or equal to 15 degrees, especially when moving at speeds slower than the walk-run transition speed. Running will be more efficient when moving at fast speeds (2,13).
When to use poles
If you have ever found yourself hiking up a conga line of ultrarunners at a large European mountain ultra, you are sure to have found yourself getting stabbed by and dodging a lot of trekking poles. Trekking poles originated in the backpacking and hiking scene but are now commonly seen at many prestigious and vert-tastic running races worldwide. We know hiking is more efficient when our speed slows on steep grades, but can the use of trekking poles make it even easier?
A lot of the initial research on trekking poles originated in the backpacking industry and concluded that on less steep slopes, up to 10% or a 6-degree incline, poles do not make hiking metabolically easier (1). Because of the additional weight and recruitment of additional muscles (hello, arms, and lats, and core!), at these lower inclines, poles do not improve efficiency. However, poles still show a lot of promise. An example of this is the rate of perceived exertion (RPE), or how hard each athlete feels like they are working, decreases with pole use, and the use of poles can decrease muscle damage during hiking and may improve muscle function the days after the hike (9).
2 recent studies by Giovanelli, et al investigated the use of poles by ultra-mountain runners at steeper grades and reiterated some of these findings (7,6). In 2019, Giovanelli et al studied slopes above 15 degrees, and found that the RPE and vertical cost of transport were lower with the use of poles on slopes above 20 degrees (6). Since laboratory data doesn’t always translate to field data, in 2021 Giovanelli, et al tested athletes on a trail that climbs 433m in 1.3km (or 1,420’ in 0.8 miles) (7). Or in layman’s terms – an extremely steep trail. When using poles, athletes completed maximum effort hill climbs roughly 30s (~2.5%) faster than without using poles (7). However, when hiking at 80% of maximum effort, poles did not impact finish time (7). Hiking with poles changes hiking gait, increasing stride length and lowering frequency allowing participants to move quicker uphill (9).
Poles have also been hypothesized to assist with stability during locomotion, something you’ve likely felt while out on the trail. In general, while running on flat, even surfaces, 2% of the energy you use to move down the path is just to maintain lateral stability (1). Thus, it shouldn’t surprise you that running on uneven terrain requires 5% more energy for stability and walking requires 26% more (16). When running on uneven terrain, you activate more muscles in your thighs and require more energy to stay upright (16). Thus, if poles can assist with stability on the trail, it is hypothesized that using poles could be even more beneficial long-term (16).
To help understand this concept, Dr. Giovanelli recommends doing a single-legged squat without poles, and then performing the same with poles and seeing how much more stable you feel. As someone who is extremely bad at single-legged squats, I am team “poles.”
Although no studies have looked into the benefits of using poles during ultra-endurance events, it can be hypothesized that poles may assist by spreading the muscle demand to other parts of the body to delay muscle fatigue and damage during a long-ultra. Additionally, they may assist with balance, which may become worse as runners’ fatigue.
What about the downhills?
Downhills are known to elicit high amounts of muscular damage due to the eccentric nature of the activity (3). High, intense amounts of downhill running can elicit high levels of circulating creatine kinase (CK), delayed onset muscle soreness (DOMS), muscle damage, and strength loss (3). This occurs due to the high amount of muscle lengthening from the braking actions during landing as you descend a steep grade (3).
We’ve all woken up the morning after an overly-ambitious trail run with a lot of downhill running to feel our quads extremely painful to the touch. This is due to the excessive downhill running on under-trained legs.
Studies have shown that when it comes to walking and running, it is easier to walk and run downhill than uphill. However, walking and running down steep slopes becomes less economical than flats after about +/-20% (11). Runners with the best running economy (~20% improvements) at steep grades were runners who had vast training and experience in downhill running (12). To date, poles have not been shown to offer any advantages to downhill running energetics (15).
Put these “poles” to practice
UTMB is right around the corner, summer is in full swing, and there are a lot of mountains in our future. Let’s hear Dr. Giovanelli’s advice for putting these tips into action in your next hilly training run or race.
Run/Hike:
- If you can sustain a fast enough speed, it is better to run (2).
- If you cannot run, especially in longer events when it is too demanding or the hills are too long, you should walk (8).
- If you cannot run, because the terrain is too steep, you should walk (8).
- Hike and run hills in training and pay attention to how you are breathing and feeling.
- Pick a training hill and hike it one day and then run it another – use your own speed, heart rate, and/or RPE to determine which is more efficient for you.
- Strength training can assist with hiking muscles.
- Focus on exercises like: lunges, step-ups, and single-leg squats to build strength for hiking.
Poles:
- It is better to use poles when you are walking uphill (>20 degrees) because you save muscular energy (7,9).
- Bring poles for the long races, because they have potential to lessen muscle fatigue, damage, and balance. These benefits likely outweigh any possible negatives.
- Start using poles at least a couple of months before your big event on long runs at a minimum once per week. This will help you become more efficient and make sure they are not detrimental to your race.
- Practice different techniques: double poling, diagonal striding, ski striding (longer strides).
- Adding in some upper body strength training before using poles will help with the transition.
- Use the poles on the type of terrain you will see on race day because techniques differ based on steepness of climbs, technical nature of the trail, and length of the climb.
- Typically, you do not need poles on flat ground or downhills, especially the faster you move, but again you might find them beneficial for balance as you become fatigued (15)
I hope to see a lot of you out on the trails practicing hiking with your poles. Don’t do what I did back in 2018 and try poles for the 3rd or 4th time ever during a race. This will spare you so much frustration, and help you feel strong on race day. This sport tests us enough, so make things a little bit easier by putting these recommendations into practice ahead of race day. It’s called power hiking for a reason!
Citations
(1)Arellano, C. J. and Kram, R. The energetic cost of maintaining lateral balance during human running. J. Appl. Physiol. 112, 427-434, 2012.
(2)Brill JW, Kram R. Does the preferred walk-run transition speed on steep inclines minimize energetic cost, heart rate or neither? J Exp Biol. 12;224, 2021. doi: 10.1242/jeb.233056.
(3)Close, G. L., Ashton, T., Cable, T., Doran, D. & MacLaren, D. P. Eccentric exercise, isokinetic muscle torque and delayed onset muscle soreness: the role of reactive oxygen species. Eur J Appl Physiol 91, 615–621, 2004.
(4)Duncan, M., and Lyons,M . The effect of hiking poles on oxygen uptake, perceived exertion and mood state during a one hour uphill walk. Journal of Exercise Physiology Online. 11: 20-25, 2008.
(5)Farley, CT, Ferris, DP. Biomechanics of walking and running: center of mass movements to muscle action. Exerc Sport Sci Rev26: 253–285,1998.
(6)Giovanelli, N., et al. Do poles save energy during steep uphill walking? European Journal of Applied Physiology. 119. 10.1007, 2019.
(7)Giovanelli N, Mari L, Patini A, Lazzer S. Pole Walking Is Faster but Not Cheaper During Steep Uphill Walking. Int J Sports Physiol Perform. 2022 Mar 22:1-7. doi: 10.1123/ijspp.2021-0274. Epub ahead of print. PMID: 35316790.
(8)Giovanelli,N, Ortiz,A, Henninger,K, and Kram, R. Energetics of vertical kilometer foot races; is steeper cheaper? Journal of Applied Physiology. 120:3, 370-375, 2016.
(9)Howatson G, Hough P, Pattison J, Hill JA, Blagrove R, Glaister M, Thompson KG. Trekking poles reduce exercise-induced muscle injury during mountain walking. Med Sci Sports Exerc.43(1):140-5, 2011;. doi: 10.1249/MSS.0b013e3181e4b649. PMID: 20473229.
(10) Knight, C., and Caldwell, G. Muscular and metabolic costs of uphill backpacking: are hiking poles beneficial? Medicine and Science in Sports and Exercise. 32:12,2093-2101, 2000.
(11)Lemire, M., Falbriard, M., Aminian, K., Millet, G.P., & Meyer, F. (2021). Level, Uphill, and Downhill Running Economy Values Are Correlated Except on Steep Slopes. Frontiers in Physiology, 12.
(12)Minetti, AE, et al. Energy cost of walking and running at extreme uphill and downhill slopes. J Appl Physiol. 93: 1039–1046, 2002.
(13) Ortiz, A.L.R., Giovanelli, N. & Kram, R. The metabolic costs of walking and running up a 30-degree incline: implications for vertical kilometer foot races. Eur J Appl Physiol 117, 1869–1876 (2017). https://doi.org/10.1007/s00421-017-3677-y
(14)Perrey S, Fabre N. Exertion during uphill, level, and downhill walking with and without hiking poles. J Sports Sci Med. 1;7(1):32-8, 2008.
(15)Saunders, M., et al. Trekking Poles Increase Physiological Responses to Hiking Without Increased Perceived Exertion. Journal of Strength and Conditioning Research.22:5,1468-1474,2008.doi: 10.1519/JSC.0b013e31817bd4e8
(16) Voloshina, A., and Ferris, D. Biomechanics and energetics of running on uneven terrain. J Exp Biol. 1:218 (5), 711–719,2015 doi: https://doi.org/10.1242/jeb.106518