CIM's net-downhill profile is the reason so many runners target it for a fast time, but a downhill course changes the pacing conversation rather than simplifying it. Running downhill well is a different skill than running flat well, and the runners who fade hardest on this course are usually the ones who treated the descents as free speed instead of a demand on very specific muscles.

The danger of a fast downhill start

The early miles above Folsom Dam invite a fast start — the road trends down, the field is fresh, and the pace can feel deceptively easy. That's exactly the trap. Going out faster than goal pace on a downhill grade doesn't just risk burning energy early the way it would on a flat course; it also accelerates the muscular damage that will make the later miles hurt more than they need to. The discipline required here is holding back on terrain that's actively encouraging you not to.

Protecting your quads on the descents

Running downhill loads the quadriceps eccentrically — the muscle lengthens under tension with every footstrike to control your descent, which causes far more microscopic muscle damage than the same effort on flat ground. The practical fix is form, not just pacing: keep your stride short and your cadence quick rather than overstriding and reaching for extra speed with each step, and try to minimize how long your foot stays in contact with the ground. Runners who let their stride lengthen on the downhills tend to feel it in their quads well before the course flattens out for good.

The rolling miles are not optional

CIM's rolling stretch through the suburbs around Fair Oaks and Carmichael isn't a short prelude — it runs far deeper into the race than the course's net-downhill reputation suggests, with genuine climbs mixed in. Treat those climbs as part of the plan, not an unwelcome surprise: settle into a slightly higher effort on the uphill sections rather than chasing even splits by pace alone, and let the following descent bring your pace back down naturally rather than forcing it.

The flat closing miles ask a different question

Once the course finally flattens out for good in its closing miles, the demand on your legs shifts from absorbing impact to simply generating forward motion — which is a problem if your quads are already trashed from mismanaging the rolling stretch. Runners who paced the rolling miles well often find the flat closing stretch is where they can actually push, finishing well rather than surviving. Runners who didn't tend to discover, somewhere around J Street, that flat ground doesn't fix legs that are already done.

Preparing your legs before race day

Downhill running is a trainable skill, not just a pacing decision made on the fly. Working some genuine downhill mileage into your final weeks — even short repeats on a moderate grade — gives your quads practice absorbing that specific kind of load before they have to do it for 26.2 miles at once. Runners who arrive at CIM having only trained on flat or uphill terrain are more likely to feel the descents as a shock partway through, rather than as familiar work their legs already know how to handle.

• Start conservatively even though the road is telling you to go faster — bank patience, not time.
• Shorten your stride and increase turnover on the descents instead of overstriding for extra speed.
• Respect the rolling miles through Fair Oaks and Carmichael as real terrain that lasts longer than you'd expect, not a minor inconvenience.
• Save your surge, if you have one, for the flat closing miles into downtown Sacramento, where the terrain finally rewards raw effort again.

Fueling on a downhill course

Pacing isn't the only thing that goes sideways when runners misjudge a downhill course — fueling often does too. It's tempting to assume a faster-than-usual pace means you're working less hard and can stretch out your gel or aid-station schedule, but the eccentric muscle damage from the descents doesn't care how easy the effort feels; your body is still burning through glycogen at a rate closer to your actual pace than your perceived effort. Stick to your planned fueling schedule based on time and distance, not on how comfortable the downhill sections feel, so you're not caught depleted once the terrain flattens out and effort finally starts matching perceived difficulty again. The same logic applies to hydration — cool morning temperatures can mask how much fluid you're actually losing, so drink on your plan rather than waiting until you feel thirsty, especially through the longer rolling stretch where the effort can feel more manageable than the pace suggests.