Excellent analysis. 15 years ago I was an over-striding heel striker and in more or less constant agony. My natural gait was definitely not optimal. Fixing the over stride adjusted me to a midfoot strike and I've been pain-free running ever since.
Preferred cadence is a by-product of fitness level and environment (including changes in ground gradient). In essence, preferred cadence is determined by muscular contractions and center of mass relative to the ground. But, this preferred cadence may or may not be optimal. Like you noted in your example, shifting cadence for a runner based on "feel" can yield good results. However, that does not conflict with optimal cadence defined by the laws of motion that also aligns with optimal biomechanics. However, biomechanics frequently conflicts with aerobic ability (or in ultra endurance events it also conflicts with metabolism efficiency). Your example of a spinning skater is correct, but it also illustrates the difference between optimal and preferred rotational speed. While tucking the arms closer increases speed, extending them may be preferable if the athlete can't maintain the physical ability needed for a faster spin. In running this ability is called aerobic capacity. However, the key distinction in the skating example is that rotational speed depends solely on momentum, as force is applied only at the beginning. In contrast, running involves both momentum and repeated force application to maintain forward motion. This is an important difference when it comes to limits defined by the aerobic capacity of the athlete. Running speed (pace) is determined by two factors: 1) Distance covered per "push-off" (stride) 2) Steps per minute (cadence) To increase pace, you must increase stride, cadence, or both. STRIDE is primarily limited by LEG LENGTH (height), while CADENCE is constrained by FITNESS level and environmental factors, unlike a skater's arm position during a spin. Laws of Motions in Physics (not ability) define most of a skaters spin while physical ability plays a bigger role in running. In short, cadence and spin are not equivalents. Spin is force applied once while cadence is force applied repeatedly. Higher cadences are typically more optimal but may not be preferred if the runner can't sustain them. Targeting higher cadences can improve fitness over time, but it won't necessarily lead to more efficient running based on overall pace for an extended race unless the runner specifically trains at that higher cadence. This is no different than training at different paces to run faster and where increasing cadence is a more universal way to increase pace since leg length is fixed. The balance between efficient pace and efficient cadence varies for each runner. However, the optimal pace based solely on physics remains constant. Achieving this balance requires individualized training and adaptation. And, where cadence is most adaptable since stride is mostly a by-product of leg length. This is why increasing cadence over time as a goal is a more effective way to improve pace. In effect, this shifts the "runner's comfort level/feel" (i.e., aerobic AND biomechanical efficiency) toward a faster pace at a faster cadence (for most).
Very good, esp.foot down or foot up. Lawrence Van Lingren coaches 'don't run towards the finish line, run the finish line to you. Imagine you are spinning the world under you'. IMO this encourages the foot to linger a bit on the ground. I ask people to imagine they are running across ants but not hurting them. My 76yo wife said she preferred thinking about running across hot coals and onour run immediately went from heavy-footed 8:00 miling to flying 6:15 miling! Only for a few hundered meters but I was amazed at the effect (foot up instead of down in hert case and reduced GCT).
Mind blowing magic discovery last running sessions: Try running as if sb. is grabbing your girdle from behind to slow you down. It will exacly feel like there's sb. behind you grabbing a hold of you and you feel your hamstrings fighting against him! On the contrary try running like sb. is pushing you forth, it will also feel like really being pushed 😅 and now the hip momentum is faster than the legs which makes the legs easy and relaxed and the heels swing up freely. Before I did so, I felt that my quads were still tense after the toe off so my heels were not free to swing up. I explain it like that: I was like jumping from leg to leg and my pelvis followed by the rolling hip momentum. But when being pushed, my hip momentum is leading the lower mechanics and forces are applied a little different and muscle reflexes are also different and there is less strain on the whole system! The leg scissoring against the resistance of being hold back is total different, but this compartment is the one that propels you forward and the objective now is to practice both aspects separately to dispense them in perfect proportion later to get the easy relaxed gait cycle and the forward pull.😊
Thanks Fredrik, I've benefited greatly from your videos! There are so many so called running form coaches giving bad and dangerous advice out in RU-vid land!
8:20 You are probably right. But lines on photos are definitely overexaggerated. On left COM line doesn't go through hip, more like through TFL. On right COM line goes more over hip joint. Also on left she is touching ground already, while on right I think she is still fully in the air.
Finally... vindicated!! I have exercise induced asthma, so would often have asthma attacks after sprints. My go to position to recover was hands on knees, but people would always lecture me to put my hands over my head... which just felt AWFUL! And the self selected cadence bit was a relief too! Heck, it was all fascinating!
Hands on your knees allows mechanical advantage to utilize more of the top portion of the lungs using the shoulders to help inhale. Hands on head eliminates that but trains the diaphragm in that moment to help make it stronger. Coaches say don’t bend over but don’t understand why they were told to say that. Both have their place.
