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6 min readrunning / training

One downhill run buys 6 weeks of quad protection

Climbing costs you during a race. Descending bills you for the three days after. I have run 100 km races, and the soreness that is still there on the Tuesday sits in my quads. Laboratory work on downhill running explains the delay, and it points to a cheap way of arriving at a hilly race with quadriceps that have already met the load.

The damage lives in the descents.

Gianluca Vernillo and colleagues tested 14 ultratrail runners before and after a mountain ultramarathon, on a treadmill at 10 km/h, level, at +5% and at -5%. After the race the energy cost of downhill running had risen 13.1%. Level and uphill running showed no change 1. The legs lost efficiency where they had to brake.

A controlled bout gives the size of the hit. Claudio de Oliveira Assumpção and co-authors had college students run 30 minutes at a -15% grade, at 70% of the velocity associated with their peak oxygen uptake. Knee extension isometric peak torque fell 36.3 ± 26% immediately afterwards and returned to baseline by 48 hours. Soreness measured 37 ± 25 mm right after the run and 45 ± 26 mm at 48 hours on a 100 mm scale 2. Half an hour of running downhill at a conversational effort takes a third of your quad strength for two days.

The second bout costs a third as much.

William Byrnes and Priscilla Clarkson ran the experiment that still sets the planning window. Three groups performed two 30-minute downhill bouts, separated by 3, 6 and 9 weeks. On the first bout, soreness peaked at 42 hours and creatine kinase rose 340%, 272% and 286% across the groups. On the second bout, the 3-week and 6-week groups rose 63% and 62%. The 9-week group repeated its first performance with no protection at all 3.

Kazunori Nosaka tracked the same effect over longer gaps, using elbow flexors and intervals of 6, 9 and 12 months. Most measures kept some protection at 6 months, and it disappeared between 9 and 12 4. The window depends on the muscle and the marker, so plan a running race around the 6-week figure from runners rather than the 6-month figure from arms.

Protection also changes how the work feels. Jason Tallis and colleagues took 10 trained female runners with no downhill experience through six alternating 5-minute level and downhill (-15%) trials, then repeated the session three weeks later. The second time, blood lactate was lower, perceived exertion in the opening trial dropped (d = 0.923) and soreness afterwards fell 5.

The adaptation carries to flat running. In the Assumpção trial, the group that had run the 30-minute descent 14 days earlier then ran 60 minutes on the level, and their isometric peak torque and late rate of torque development came through it unaffected 2.

The dose is smaller than the race.

Sumiaki Maeo and co-authors ran the cheapest version of this. Thirty-six untrained men, 12 per group: one group walked 5 minutes downhill at -28% and 5 km/h carrying 10% of body mass, one walked 5 minutes on the level with the same load, one did nothing. A week later all three walked 40 minutes down the same -28% grade. The 5-minute bouts moved nothing: no strength loss, no creatine kinase rise, no soreness. After the 40-minute walk, the control and level-walking groups showed the expected damage and the downhill-walking group was protected 6.

Lachlan Boyd and colleagues pooled the preconditioning literature in 2023. Creatine kinase came out lower in preconditioned groups at 24 hours (SMD -1.64), 48 hours (-2.65), 72 hours (-2.39) and 96 hours (-3.52), and delayed-onset soreness at the same four points (-1.89, -2.50, -2.73, -3.30). Eccentric contractions protected better than isometric ones, and higher volume, greater intensity and longer muscle lengths each added protection 7.

Those two results pull in opposite directions on dose. Five minutes of downhill walking buys protection with no soreness; a harder bout buys more protection and costs you two days. Pick according to how much recovery time the block can spare.

Stride length does not change the damage.

Roger Eston's group tested the advice runners pass around on descents. Eighteen men and women did two downhill runs 5 weeks apart, the second at an 8% lower stride frequency, an 8% higher one, or their usual one. Muscle tenderness, creatine kinase and maximal isometric force came out the same across the three groups 8. Quicker steps may serve your footing and your knees; the damage markers stay where they are.

The protocol.

  1. Count back 6 weeks from a hilly race and mark the first downhill session there. Protection held at 3 and 6 weeks in Byrnes' runners and was absent at 9 3.
  2. Make that first session 5 minutes of steep downhill walking, with a pack at roughly 10% of body mass. That dose produced no measurable damage and still protected a 40-minute descent a week later 6.
  3. Two weeks out from it, run 20 to 30 minutes of continuous descent at a conversational effort, near 70% of your velocity at VO2max. Budget for a third of your quad strength gone that evening and soreness peaking around 42 to 48 hours 23. Schedule nothing hard in those two days.
  4. Repeat the running version every 2 weeks and place the last one 10 to 14 days before the race. The transfer in Assumpção's trial was measured at a 14-day gap 2.
  5. Score your soreness at 24 hours on a 0 to 100 scale after every downhill session and write it down. A second score near half the first means the adaptation took; a score as high as the first means the gap was too long.
  6. Leave your stride out of it and spend the attention on footing and fueling 8.
  7. Do the same thing before a flat marathon if your legs fade late. The 14-day downhill bout protected a 60-minute level run in the only trial that tested the transfer 2.

A 5-minute walk down a hill looks like nothing on a training log, which is why it gets dropped. Put it in the calendar 6 weeks out, then compare the two 24-hour soreness scores.

Sources.

  1. Vernillo, G., Savoldelli, A., Zignoli, A., Skafidas, S., Trabucchi, P., La Torre, A., Pellegrini, B., & Schena, F. (2015). Energy cost and kinematics of level, uphill and downhill running: fatigue-induced changes after a mountain ultramarathon. Journal of Sports Sciences, 33(19), 1998-2005. doi.org/10.1080/02640414.2015.1022870
  2. de Oliveira Assumpção, C., Barreto, R. V., de Lima, L. C. R., Cardozo, A. C., Montebelo, M. I. L., Catarino, H. R. C., Greco, C. C., & Denadai, B. S. (2020). A single bout of downhill running attenuates subsequent level running-induced fatigue. Scientific Reports, 10, 18874. doi.org/10.1038/s41598-020-76008-2
  3. Byrnes, W. C., Clarkson, P. M., White, J. S., Hsieh, S. S., Frykman, P. N., & Maughan, R. J. (1985). Delayed onset muscle soreness following repeated bouts of downhill running. Journal of Applied Physiology, 59(3), 710-715. doi.org/10.1152/jappl.1985.59.3.710
  4. Nosaka, K., Sakamoto, K., Newton, M., & Sacco, P. (2001). How long does the protective effect on eccentric exercise-induced muscle damage last? Medicine & Science in Sports & Exercise, 33(9), 1490-1495. doi.org/10.1097/00005768-200109000-00011
  5. Tallis, J., McMorrow, C., Shelley, S. P., & Eustace, S. J. (2024). Repeated bout effect of downhill running on physiological markers of effort and post exercise perception of soreness in trained female distance runners. Sports, 12(6), 169. doi.org/10.3390/sports12060169
  6. Maeo, S., Yamamoto, M., Kanehisa, H., & Nosaka, K. (2017). Prevention of downhill walking-induced muscle damage by non-damaging downhill walking. PLOS ONE, 12(3), e0173909. doi.org/10.1371/journal.pone.0173909
  7. 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. doi.org/10.1007/s40279-023-01839-8
  8. Eston, R. G., Lemmey, A. B., McHugh, P., Byrne, C., & Walsh, S. E. (2000). Effect of stride length on symptoms of exercise-induced muscle damage during a repeated bout of downhill running. Scandinavian Journal of Medicine & Science in Sports, 10(4), 199-204. doi.org/10.1034/j.1600-0838.2000.010004199.x

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