What comes up…

…must come down. Learn about the mechanism that makes dedicated downhill running an invaluable tool for your mountain races.

I bet not a single soul reading this has evaded the unmistakeable sensation of DOMS – the delayed onset muscle soreness. Pretty descriptive term. In German it’s called “Muskelkater” which roughly translates into hangover of the muscle, which is also quite fitting, as you do not pay the price for the fun you’re having (e.g. hard workout) until several hours later. However, I hope for all of you out there that your hangover subsides from that point on and unlike DOMS does not peak until 1 to 2 days later.

In spite of the eponymous delay you already often know during or directly after the workout that DOMS will be a likely visitor later on. May it be because it was your first session after a longer period of rest, a particular hard session that exceeds your normal workload or exercises with a heavy eccentric focus (the movement phase during which a muscle resists its lengthening i.e. lowering yourself during a squat is an eccenric movement for your quads). After a while we get a good feeling of when DOMS are imminent and we can also be quite certain that repeating the same session next week will evoke less severe symptoms.

Dapper Downhills

Downhill running fits at least one of the predictors: It’s leaning heavy on the eccentric side of things. And if you’re not incorporating downhills in your training you can cross off the triple: Eccentric focus, haven’t done it for a long time and exceeding your usual workload. So right there we’d have already excellent indicators that specific downhill sessions or alternative eccentric loading should become part of race preparation. It flawlessly ties back to the SAID principle (specific adaptations to imposed demands), not only from a DOMS perspective but also to improve your movement pattern downhill and make it more economically. Your brain learns to only recruit the muscles necessary to descend swift and safely and does not waste energy on excessive antagonist-recruitment.

Now if we were to set these economy-improvements aside one could argue that for a race lasting ‘only’ 5 hours we could omit specific downhill training. What do I care if I’m sore after the race?

That’s where it gets interesting

DOMS is one of these concepts in sports and exercise science that have been widely known even outside of exercising populations for a long time and are still far from being fully understood. Assumptions and models as to why they happen and what exactly causes it are developing and evolving over the years. Other representatives of this category are for example muscle cramps and fatigue in general.

The idea that symptoms of DOMS are mainly caused by micro-ruptures in muscle fibres has been around for over a century now. And not unjustified: These ruptures often play a part in DOMS, but they are neither the complete explanation nor the necessary condition. More recent work has hypothesized that repeated eccentric loading leads to excessive compression inside our muscles ultimately causing microinjuries of muscle nerve-endings. Specifically those that send proprioceptive information from out skeletal muscle towards the brain.¹ The proposed causal compression is elicited in the lengthened muscle position at a point where the fluid in the intrafusal-surrounding cavity cannot be compressed any further thus creating high compression forces on said nerve-endings. This mechanism would track with our anecdotal experience that eccentric exercise is a main culprit in the case of DOMS. During purely concentric exercise these lengthened positions under tension rarely occur.

Now I want to say 3 things about the work I just referenced:

• It’s theoretical work that proposes a DOMS-mechanism from a multitude of previous studies
• Some of the studies Sonkodi et al. reference were done on frogs, rats, mice etc.
• Their proposed mechanism involves much more than just the compression-thingy I just yapped about. One of the many predictions is that DOMS have early-onset consequences before you feel it

Wobbly Now, Ouchie Later

And this could have real practical implications for us. If there were a more immediate component of DOMS that limits us way before the well known symptoms several hours later set in, taking measurements to avoid or delay any DOMS response would become relevant even in shorter mountain races. Lucky for us, Sonkodi et al. did their theorizing in 2020 and since then published a clinical study that aimed to put their assumptions to the test. They measured professional Hungarian handball players stretch reflex response of the quadriceps femoris before and after a multi-stage fitness test. Result: The EMG showed a statistically significant delay in the medium-latency response of the stretch reflex. Measurable directly after the fitness-test, hours before typical symptoms woul be felt.²

Okay, so DOMS-inducing exercise makes your muscles talk delayed to the brain. Why bother? Well, because your running economy will suffer, as work from Khassetarash et al. showed in 2022. During a 30-min downhill run leg stiffness and joint quasi-stiffness were reduced (-11.7% and -25.4% respectively), participants could produce less force and ground contact time increased as flight time decreased. This has not only performance but also injury-prevention implications.

What to do about it?

In contrast to the neuro-physiological mechanism behind the immediate DOMS effects the countermeasure is quite simple: Downhill running! The aforementioned research group had their participants come in one week later and perform the same 30-min downhill sesh. During the second bout

• no reduction in leg stiffness and joint quasi-stiffness was observable
• alterations in ground contact time and flight time were smaller
• reduction in maximum voluntary isometric contraction were attenuated
• participants showed less energy absorption and energy generation i.e. being more economical

Their findings indicate that specific downhill training may not completely prevent these alterations in running economy but can attenuate the effects and allow you to perform longer DOMS-inducing downhills before the alterations set in.

Training Implications

In the study participants did their downhill running on a special instrumented treadmill at a -12% grade running ~6min/k (~9:39/mi). Undoubtedly parameters many of us will have difficulties to hit on the home turf. And luckily we don’t have to. Do not stress about the specifics too much. Just use what is available to you! Ideally you have some incline or slope nearby that you already may utilize for hill-reps. You can even combine both aspects and do your recovery jog down after longer hill-reps with more intention. Be mindful of overall stress though. Dial back your reps or the intensity from what you are currently doing if you are swapping recovery jogs down with faster downhill-specifics.

Should the topography around you be as flat as flatbread (common analogy, I’m sure) you can resort to the next best thing: Preconditioning in the weight room. Analogous to the single bout of 30-min downhill running even one session can have a protective effect.⁴ What does a weightroom session look like, that works well in this regard?

• rather 2-4 days before the DOMS inducing bout than 1-3 weeks prior
• greater volume (10-30 eccentrics) performs better than lower (2-6)
• prefer higher intensities (20-80% voluntary peak force)
• utilize lengthened muscle position
• prefer eccentrics over isometrics

As you can see the ranges are pretty broad and please notice that the less preferred protocols still have an protective effect. The optimal protocol is not the one that has the highest protective effect, but the one that you actually execute. Find what you can stomach or even enjoy a little bit and rest easy knowing that anything you did was better than doing nothing!

References

[1] Sonkodi, B., Berkes, I., & Koltai, E. (2020). Have We Looked in the Wrong Direction for More Than 100 Years? Delayed Onset Muscle Soreness Is, in Fact, Neural Microdamage Rather Than Muscle Damage. Antioxidants (Basel, Switzerland), 9(3), 212. https://doi.org/10.3390/antiox9030212

[2] Sonkodi, B., Hegedűs, Á., Kopper, B., & Berkes, I. (2022). Significantly Delayed Medium-Latency Response of the Stretch Reflex in Delayed-Onset Muscle Soreness of the Quadriceps Femoris Muscles Is Indicative of Sensory Neuronal Microdamage. Journal of Functional Morphology and Kinesiology, 7(2), 43. https://doi.org/10.3390/jfmk7020043

[3] Khassetarash, A., Baggaley, M., Vernillo, G., Millet, G. Y., & Edwards, W. B. (2022). The repeated bout effect influences lower‐extremity biomechanics during a 30‐min downhill run. European Journal of Sport Science, 23(4), 510–519. https://doi.org/10.1080/17461391.2022.2048083

[4] Boyd, L., Deakin, G. B., Devantier-Thomas, B., Singh, U., & Doma, K. (2023). The Effects of Pre-conditioning on Exercise-Induced Muscle Damage: A Systematic Review and Meta-analysis. Sports Medicine, 53(8), 1537–1557. https://doi.org/10.1007/s40279-023-01839-8