HomeRunningDeodorant, Downhill Quads Seasoning, and Slushies – iRunFar

Deodorant, Downhill Quads Seasoning, and Slushies – iRunFar

Welcome to a different version of Working on Science’s Truth or Fiction, the occasional myth-busting model of our column.

This spherical, we check out three extra intriguing matters that you will have heard on the path. Will deodorant impair your sweating? Will one good downhill session bulletproof your quadriceps? Whereas slushies for dessert are scrumptious, are ice slurries dangerous in competitors? As all the time, we are going to make the most of present scientific literature, and a few crucial considering, to assist us perceive if these factoids are truth, fiction, or one thing in between.

Truth or Fiction: “Don’t put on deodorant; you’ll overheat.”

Please inform me you watched the 2022 World Athletics Championships, which happened in Eugene, Oregon? Aspect notice, they have been superb! As temperatures crept up through the week, a broadcast commentator stated that athletes wanted to keep away from sporting merchandise like lotion and deodorant whereas competing within the warmth as each might alter their potential to sweat. Keep in mind, we make the most of sweat for evaporative cooling to assist thermoregulate, and this turns into increasingly more vital in sizzling climate (1). Disrupting this looks like hassle. However is deodorant such a disruptor?

First issues first, what’s deodorant and the way does it work? Deodorant is technically a magnificence product designed for destroying and masking odors. It really works by killing the micro organism that trigger odor and helps masks the odor of sweat with fragrance. Critically, it doesn’t block your sweat glands.

Antiperspirant, a skincare product, alternatively, works by eliminating the sweat that causes the odor. It does so by using aluminum that, when uncovered to sweat, creates a gel-like substance that plugs the sweat glands in your axillary or armpit area for twenty-four to 48 hours, relying on the product. Each deodorant and antiperspirant cease odor, one thing many people are keen on, however is obstructing the sweat ducts in your armpits with antiperspirant sufficient to have an effect on thermoregulation?

Rexona Men antiperspirant

Many manufacturers of antiperspirants are labeled to be used in sport. Photograph: Arief Budi Kusuma/Shutterstock

It seems that axillary sweating makes up lower than 1% of your entire physique’s sweat price. Whereas using antiperspirant may cease you from being the sweaty armpit individual — I’m responsible right here — it’s not a big sufficient area to have an effect on your physique’s potential to thermoregulate, even whereas exercising in sizzling environments (1, 2).


Fiction! First issues first, deodorant doesn’t work the identical manner as an antiperspirant. However many deodorants are mixed with an antiperspirant, so yours may include the sweat gland-plugging ingredient, too. However our armpits should not that massive of a area, and you’ve got sweat glands throughout your physique that do the work of thermoregulating for you.

Regardless of the proof, if that is one thing you’re apprehensive about on your upcoming sizzling climate race, use a pure deodorant that doesn’t include aluminum.

Truth or Fiction: “You solely want one good downhill session earlier than your subsequent path race.”

Who isn’t apprehensive about blowing up your quadriceps throughout your massive race? It’s on my record of worst-case situations and has led to me telling my crew, “I don’t care if I get handed by 100 individuals so long as my quads hold working!” Most of the methods we put together for racing a protracted race are by doing issues again and again.

We follow our diet, we run hills, we log miles and hours — and that repetition is overwhelmingly protected. With regards to operating downhill, and the precise neuromuscular and musculoskeletal calls for it presents, attacking it repeatedly may put you on the injured record as an alternative of the beginning line.

How will we counter this? Enter the previous adage: To “season” the quads, you solely want one good downhill session. Is that true, and the way does it work?

Hillary Allen - 2017 Transvulcania Ultramarathon third place

Hillary Allen on the underside a part of the Transvulcania Ultramarathon’s quadriceps-busting 8,000-foot descent in 2017. Photograph: iRunFar/Meghan Hicks

The calls for positioned in your physique for downhill operating differ vastly from operating on flat or uphill surfaces. That is largely as a result of downhill operating requiring eccentric muscle activation, which signifies that the muscle lengthens as it’s activating, and the reward that’s gravity. Fortunately, the scientific neighborhood is aware of quite a bit about eccentric contractions and the way they affect muscle physiology and we are able to apply that on to path operating and ultrarunning.

Enter, the repeated bout impact (RBE). RBE is a phenomenon through which skeletal muscular tissues adapt protectively towards future muscle injury after the introduction of a novel eccentric train (3). Primarily, one preliminary bout of eccentric work causes long-term safety, as a result of speedy neural adaptions and structural transforming (4). Or, one bout of delayed onset muscle soreness (DOMS) goes a great distance!

Whereas this has been studied within the power and conditioning world for a number of many years, it has additionally been put into follow within the operating world. Researchers within the Human Efficiency Lab on the College of Calgary, in Alberta, Canada, introduced leisure runners into the lab to run for half-hour at a slope of -20% — a reasonably steep downhill — at 2.8 meters/second or roughly 9:34 minute/mile (4).

They repeated the check three weeks later. They measured neuromuscular fatigue, flat floor operating biomechanics, and operating financial system at 24, 48, 72, 96, and 168 hours post-downhill session. What they discovered was that muscle soreness, neural fatigue, and maximal voluntary power manufacturing have been improved after the second session in comparison with the primary run (4). RBE was at work. The runners’ skeletal muscular tissues tailored protectively with a particularly small dose of downhill operating.

China’s Can-Hua Luo heads out of Vallorcine, France, and towards the ultimate climb and descent of the 2019 UTMB. By this level within the race, many runners will likely be feeling the results of the race’s many lengthy descents on their quads. Photograph: iRunFar/Kirsten Kortebein

A caveat, as with every examine, the scope is proscribed to what they examined and the way they examined it. With regards to downhill operating, the aim of using RBE is to attempt to restrict neuromuscular fatigue on race day, which makes your quads really feel like Jell-O. RBE doesn’t, nonetheless, improve ability on say, technical downhills.

Moreover, they examined three weeks after the primary downhill bout so we don’t know precisely how lengthy the impact lasts past that. What meaning in follow is that placing the downhill RBE to work might be a good suggestion for the runnable downhills of the Western States 100, however this shouldn’t be your solely type of downhill follow forward of the technical downhills of The Rut 50k.


Truth! Because of the repeated bout impact, you possibly can in actual fact “season” these quadriceps with out throwing your self downhill day in and time out. These variations happen fairly shortly, with little to no upkeep, and final for, at a minimal, a number of weeks.

Truth or Fiction: “Keep away from ice slushies on the run!”

After I requested for beta on crewing and pacing Badwater 135, I used to be informed explicitly to search out myself a slushy on the fuel station and common retailer once we made it to Panamint Springs Resort. I had simply completed a 14-mile stretch of operating the place the valley air temperature was creeping towards 130 levels Fahrenheit (54 levels Celsius) and we have been recording floor temperatures of 147 Fahrenheit (63 Celsius). I used to be melting.

However I positioned the candy nectar of the gods within the type of a strawberry-flavored slushy. As I slurped, I assumed, I’d kill for considered one of these throughout a race! However hadn’t I written the article Keep Cool: Cooling Strategies in Endurance Working advising readers to keep away from this very factor for mid-race cooling?

With regards to cooling methods, ice slushies or slurries will be very efficient in lowering physique temperature. It is because it takes extra vitality to show to show ice into liquid than it does to heat up chilly water. How this works in follow is that internally the ingestion of an ice slurry introduces an extra avenue for warmth to be transferred (5).

We all know the ingestion of an ice slurry pre-exercise has been proven to cut back core physique temperature by 0.5 diploma Celsius (about 1 diploma Fahrenheit) (6). The profit to this, notably in shorter races, is that you simply begin the recent effort with one other diploma of inside warmth capability, or extra wiggle room earlier than you doubtlessly overheat. Comparable advantages, post-exercise, ice slurry consumption appears to supply the marginally decrease core physique temperature as in comparison with chilly water immersion (7).

Tyler Green - 2021 Western States 100 - Rucky Chucky

Tyler Inexperienced cooling off within the American River at mile 78, on his solution to taking second on the 2021 Western States 100. Photograph: iRunFar/Bryon Powell

All of this goodness stated, the rationale we’ve urged avoiding ice slurries throughout your sizzling race is as a result of the drink is mostly so chilly that it may possibly activate thermoreceptors, which detect temperature change, in your stomach. When these receptors are activated, your physique will be tricked into considering you’re cooler than you’re and result in a discount in sweating. Keep in mind that sweating is considered one of our greatest methods to dump warmth into the atmosphere, and a discount in that may very well be problematic.

What occurs when you find yourself in an atmosphere the place you possibly can’t absolutely profit from evaporation, equivalent to a sizzling, humid atmosphere and/or a spot with poor air circulation? That is what you’ve been ready to listen to in the event you reside in humid climates! That’s proper, in case you are coaching or competing in an space the place sweat effectivity is poor and your sweat is dripping or pooling as an alternative of evaporating, the ingestion of ice slushies might in actual fact be for you (6).


It’s a draw! Like many issues in life, time and place are vital. Pre- and post-hot race, it’s protected to succeed in for that ice slushy, as you’ll profit from a lower in core physique temperature. With regards to mid-race indulgence, take into consideration sweat effectivity. If it’s dry and your sweat’s evaporation price is excessive, then deal with staying moist (ice goes on the skin). And if it’s sizzling and humid, or there’s no wind and also you’re making a puddle of sweat, then give a slushy a attempt (ice goes on the within).

Name for Feedback

  • Have you ever tried operating a sizzling race with and with out antiperspirant? Discover any vital variations?
  • Do you think about arduous downhill efforts as a part of your extremely coaching?
  • Have you ever tried ice slushies throughout a race and the way did it go?


  1. Burry JS, Evans RL, Rawlings AV, Shiu J. Impact of antiperspirants on entire physique sweat price and thermoregulation. Int J Cosmet Sci. 2003 Aug;25(4):189-92. doi: 10.1046/j.1467-2494.2003.00184.x. PMID: 18494900.
  2. Everts, S. (2022).The enjoyment of sweat: The unusual science of perspiration. W. W. Norton & Firm, Inc.
  3. Hyldahl RD, Chen TC, Nosaka Okay. Mechanisms and Mediators of the Skeletal Muscle Repeated Bout Impact. Exerc Sport Sci Rev. 2017 Jan;45(1):24-33. doi: 10.1249/JES.0000000000000095. PMID: 27782911.
  4. Khassetarash, A., Vernillo, G., Krüger, R. L., Edwards, W. B., & Millet, G. Y. (2022). Neuromuscular, biomechanical, and energetic changes following repeated bouts of downhill operating.Journal of Sport and Well being Science11(3), 319–329. https://doi.org/10.1016/j.jshs.2021.06.001
  5. Osakabe, J., Matsumoto, T., & Umemura, Y. (2019). Ice slurry ingestion as a cooling technique within the warmth. The Journal of Bodily Health and Sports activities Medication,8(2), 73-78. doi:10.7600/jpfsm.8.73
  6. Mejuto, G., Chalmers, S., Gilbert, S., & Bentley, D. (2018). The impact of ice slurry ingestion on physique temperature and biking efficiency in aggressive athletes. Journal of Thermal Biology,72, 143-147. doi:10.1016/j.jtherbio.2018.01.012
  7. Stanley, J., M. Leveritt, and J.M. Peake (2010). Thermoregulatory responses to ice-slush beverage ingestion and train within the warmth. J. Appl. Physiol.110:1163–1173.


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