The first and most famous belief is what the authors call the heel-strike fallacy: the idea that rearfoot striking is inherently harmful because it produces greater impact loading and therefore higher overuse injury risk. The narrative began with foundational biomechanical studies characterizing the sharp impact transients visible in force-time curves of heel strikers. Early clinical accounts proposed that accumulated impact loading could contribute to running injuries, and retrospective findings in a specific population of competitive runners associated rearfoot striking with higher injury rates. In the 2000s, the barefoot and minimalist movements, amplified by bestselling books and influential research on habitually barefoot populations, turned this hypothesis into consumer gospel: avoid heel strike, prevent injury, run better.

Yet the observed behavior of actual runners is difficult to reconcile with this narrative. Most endurance runners naturally adopt a rearfoot strike, with studies reporting the pattern in at least 55 percent of elite and 90 percent of recreational marathon runners. One recent analysis using high-speed plantar-pressure measurements in 104 distance runners identified a rearfoot strike in 92 percent of all analyzed foot contacts. Its spontaneous and stable adoption across runners with different morphologies, footwear, and training histories suggests that heel striking represents a common movement solution rather than an inherently maladaptive one. Running gait, the review argues, self-organizes through repeated practice toward patterns that balance energetic cost, mechanical loading, and comfort within each runner’s individual constraints.

The empirical case against the fallacy is more nuanced than a simple reversal. Cross-sectional analyses reveal that rearfoot striking is not consistently associated with higher external impact-related metrics such as vertical loading rate. Across independent datasets, the relationship between foot-strike angle and vertical loading rate appears curvilinear: mild rearfoot strikers, landing at roughly five to ten degrees, displayed higher loading rates, whereas lower values occurred in some pronounced rearfoot and forefoot strikers. A striking case study illustrates the point: an exceptionally high-mileage runner who completed one hundred marathons in one hundred days displayed a pronounced rearfoot strike angle of 29 degrees together with a peak vertical loading rate 57 percent lower than matched heel-striking controls. Low loading rates, in other words, can occur across the entire foot-strike spectrum rather than belonging exclusively to one category.

A deeper conceptual problem underlies the fallacy: the conflation of external ground-reaction forces with internal tissue loading. Loading rates and tibial accelerations describe the external or segmental response to impact, but they do not directly quantify the forces and stresses experienced by bones, tendons, and joints. Internal loading depends substantially on muscle forces, joint geometry, tissue properties, and how forces are distributed along the kinetic chain. Modeling work has shown that impact transmission is modulated by neuromuscular control and soft-tissue damping, and one study demonstrated that although forefoot and rearfoot runners display distinct impact-shock profiles, the attenuation of these vibrations through the body is comparable. Most tellingly, recent musculoskeletal modeling in habitual heel strikers showed that imposing a non-habitual forefoot strike increased distal tibial loading compared with both habitual and imposed rearfoot conditions. Changing where the foot lands does not necessarily reduce the load on the bone inside.

Prospective studies and systematic reviews do not generally support isolated external biomechanical measures as robust predictors of running-related overuse injury. A recent review concluded that vertical loading rate alone is insufficient to establish causal mechanisms for running injury, and the relationship between foot-strike pattern and injury risk remains undetermined because the available evidence is largely retrospective. Overuse injury risk, the review emphasizes, emerges from interactions among external mechanics, neuromuscular control, tissue adaptation, training exposure, and task conditions, not from the point of ground contact alone. Theoretical frameworks such as Nigg’s muscle-tuning paradigm and the preferred movement path concept instead interpret impact as one component of anticipatory regulation: runners self-select coordination patterns that stabilize limb motion and regulate loading in response to perceived comfort and energetic cost.

The second belief, the universal cadence rule, holds that roughly 180 steps per minute represents an optimal cadence for all runners. The number originated from observations of competitive distance runners, in whom an average cadence near 180 was reported. Over time, this descriptive value became a normative target, embedded in gait-retraining approaches and now monitored in real time by wearable devices. But extensive evidence shows cadence varies widely among endurance runners, typically ranging from 150 to 210 steps per minute. Laboratory studies consistently reveal a U-shaped relationship between cadence and metabolic cost, with each runner exhibiting a distinct preferred cadence that minimizes oxygen consumption. Cadence also increases with running speed, varies with leg length and body mass, differs across stages of physical maturation in adolescents, and shifts dynamically with footwear and surface. Barefoot running typically raises cadence by four to six percent compared with shod running, while compliant surfaces such as grass or sand can increase it by five to ten percent.

The third belief, the cadence prescription, asserts that systematically increasing cadence while holding speed constant consistently reduces mechanical loading and injury risk. Early laboratory studies showed that acutely raising cadence at a fixed speed could reduce selected internal and external loading measures, including patellofemoral joint force and loading rate. These effects were observable, easy to cue, and biomechanically intuitive, which facilitated their translation into generalized corrective strategies. However, the review introduces a crucial complication: cadence describes how frequently steps occur but not how each stride is distributed between stance and flight. That distribution is captured by the duty factor, the proportion of the stride spent in contact with the ground. Among studies that measured duty factor, increases in cadence were systematically accompanied by higher duty factors, suggesting that some loading changes attributed to cadence may be partly mediated by concurrent changes in temporal organization. Experimental work has shown that duty factor can be modulated through stance- or flight-time instructions without clear changes in cadence, and that cadence and duty factor can be independently manipulated across a functional range during endurance running. Recent studies found that increasing duty factor reduced peak joint reaction forces and extensor moments across the ankle, knee, and hip, while cadence produced weaker and more variable effects on internal loading.

None of this means duty factor is simply a new universal target to replace the old one. The observed effects are structure-specific, derived predominantly from acute biomechanical and modeling studies, and clinical evidence does not support a uniformly beneficial direction of stance-time modification. During rehabilitation for exercise-related lower leg pain, improved patient-reported outcomes have been associated with reduced duty factor, while conversely, shorter stance time has been identified as a potential risk factor for bone stress injury in collegiate runners. Temporal modifications redistribute loading rather than uniformly reducing it, and their clinical relevance depends on the tissue, the condition, the runner, and the task. The same logic applies to foot-strike: predictive simulations across 44 different cost functions showed that rearfoot striking emerged most frequently and was optimal for objectives related to whole-body energy expenditure and peak joint contact forces, whereas non-rearfoot patterns were favored for other objectives, including more evenly distributed muscle loading. No single pattern is optimal independently of the functional objective being considered.

The practical implications are substantial for clinicians, coaches, and the wearable technology industry. Before modifying running mechanics, practitioners should determine whether change is warranted at all, preserving habitual mechanics in asymptomatic runners without relevant limitations. When modification is indicated, the symptomatic tissue and intended objective should be defined first, and cadence may be tested where condition-specific clinical evidence exists, particularly in runners with patellofemoral pain, where direct clinical evidence supports cadence-based gait retraining. Success should be judged by symptoms, tolerance, function, and task-specific performance rather than by achievement of a predetermined number. The review also cautions against aesthetic judgments: movement patterns that depart from conventional running styles, including grounded running without a flight phase, may reduce selected loading measures while appearing less conventionally athletic. Runners self-optimize within their constraints, achieving similar energetic efficiency through diverse styles. The future of gait retraining, the authors conclude, lies not in universal prescriptions but in cultivating adaptive coordination through targeted constraints, progressive feedback, and context-specific practice, with researchers urged to measure both prescribed and achieved biomechanical changes alongside clinical outcomes to finally close the gap between what a force plate shows and what a runner actually experiences.

Subject of Research: The Heel-Strike Fallacy and Cadence Beliefs in Distance Running: A Narrative Review

Article Title: The Heel-Strike Fallacy and Cadence Beliefs in Distance Running: A Narrative Review

Article References: Patoz, A., Gindre, C., Lussiana, T., & Breine, B. (2026). The Heel-Strike Fallacy and Cadence Beliefs in Distance Running: A Narrative Review. Sports Medicine – Open, 12(1), Article 149. https://doi.org/10.1186/s40798-026-01120-y

Image Credits: AI Generated

DOI: 10.1186/s40798-026-01120-y

Keywords: running biomechanics, gait retraining, cadence, foot strike, duty factor, injury prevention, Sports Medicine, Heel-Strike, Fallacy, Beliefs, Distance, Running

The study, published in the journal Sports Engineering, set out to answer a deceptively simple question: does a running shoe behave the same way when it is compressed straight down as it does when it is compressed at the angles produced by real foot strikes? Standard test methods, including the widely used ASTM F1614 protocol, prescribe uniaxial loading in which the shoe is squeezed perpendicular to its sole. Yet runners rarely land that way. Rearfoot strikers contact the ground heel-first with the sole inclined roughly 16 to 20 degrees above horizontal, while forefoot strikers land on the ball of the foot with the sole tilted about 15 to 19 degrees in the opposite direction. Those angular differences change which part of the midsole absorbs the load and how much foam is engaged.

To capture this, the team tested six women’s US size 8.5 running shoe constructions that differed in midsole material, hardness and stack height. Two commercial New Balance models, the 880 with a 34.5 millimetre stack and the 1080 with a 40.5 millimetre stack, provided the basis for constructions built on production tooling, meaning the midsoles were representative of retail footwear. The materials spanned the two foams that dominate the modern market: ethylene-vinyl acetate, or EVA, the long-standing workhorse valued for cushioning, durability and low cost, and polyether block amide, or PEBA, the high-resilience superfoam behind today’s performance racing shoes. PEBA was tested at two hardness levels, 37 and 50 Asker C, while EVA was available only at the harder 50 Asker C grade.

Each shoe was fitted over a rigid mechanical last shaped to a size 8.5 foot and mounted on an Instron ElectroPuls E3000 testing machine. The last could be rotated about its transverse axis, allowing the researchers to load the shoe at three orientations: 15 degrees of dorsiflexion to mimic a rearfoot strike, a neutral 0 degrees for a midfoot strike, and 15 degrees of plantarflexion for a forefoot strike. Every cycle ran from a 50 newton preload to a peak force of 1500 newtons, roughly 2.5 times the body weight of a 60 kilogram runner, applied as a sinusoidal waveform at 1.5 hertz under closed-loop force control. Because the waveform shape and peak force were held constant, orientation was the only loading variable that changed. Each shoe received 30 preconditioning cycles before testing, and 25 cycles were recorded at each orientation, with the first five discarded to let the foam settle after repositioning.

From the force-displacement data the researchers extracted three outcomes. Vertical stiffness was calculated as the gradient of the loading curve between 70 and 90 percent of peak force, a range that avoids the nonlinear toe region at low loads and the densification zone near maximum compression. Peak displacement was the compression recorded at peak force. Energy return percentage was the energy recovered during unloading, obtained by trapezoidal integration, expressed as a fraction of the energy absorbed during loading. After removing 17 outlying cycles, or 4.7 percent of the dataset, by an interquartile range rule confirmed by curve inspection, 343 observations remained for statistical modelling.

The results were striking in their consistency. In every single shoe construction, stiffness was lowest under dorsiflexion, the rearfoot-strike orientation, and peak displacement was highest under the same condition. Compared with neutral loading, dorsiflexion reduced stiffness by 72 newtons per millimetre in the material-comparison model and increased peak displacement by 8.6 millimetres. Plantarflexion produced the same pattern of softer, deeper compression but with smaller magnitudes, a 37 newton per millimetre stiffness reduction and 2.4 millimetres of extra displacement. In the second model, comparing soft and hard PEBA, the orientation effects were smaller for stiffness but nearly identical for displacement, at 8.3 and 2.3 millimetres. All of these effects were statistically significant.

The physical explanation lies in contact geometry. When the shoe is tilted relative to the applied load, the region and volume of foam engaged during compression change, reducing the amount of material available to support the force. With less foam doing the work, the midsole compresses further under the same load. Dorsiflexion produced the larger effect, which the authors attribute to the reduced contact area associated with angled loading on the curved rearfoot geometry. The findings extend earlier work by Mohammadi and Nourani, who reported that compression angle affected strain energy in EVA soles, and they align with the observation that rearfoot and forefoot strikers load different regions of the midsole during running. In other words, the orientation effects observed in the laboratory are mechanically relevant to what actually happens on the road.

Energy return told a different story. Of the three outcomes, it was the least sensitive to loading orientation, and most of its variance was explained by differences between shoe constructions rather than by the angle of loading or the number of cycles. In the material comparison, the contrast between EVA and PEBA accounted for a large share of the variance, with PEBA showing a non-significant trend toward higher energy return and significantly greater peak displacement. In the PEBA hardness comparison, hardness itself explained very little, suggesting that the differences between soft and hard PEBA shoes reflect features other than durometer, possibly including geometry or microstructure that the study did not characterise. This supports the researchers’ hypothesis that energy return, being rooted in material-level properties, would remain relatively stable across orientations.

The study also documented a subtle but important drift across the 20 analysed cycles. Peak displacement and energy return changed slightly and linearly with successive loading cycles, meaning that the value measured depends on how many cycles precede the measurement. A standard single-orientation, fixed-cycle test captures neither this cyclic drift nor the orientation sensitivity, so it may not represent the stiffness and displacement a runner actually experiences. The authors are careful to note that the standard test remains a useful benchmark, but they argue that a fuller characterisation of running-relevant loading requires more than one orientation and a stated cycle count. Because rearfoot cushioning properties are known to influence vertical ground reaction forces during heel-toe running, the orientation-dependent differences could carry biomechanical consequences in actual use.

The researchers acknowledge several limitations. Only one shoe was tested per material-hardness-stack-height combination, so manufacturing variability could not be assessed, and with just two constructions per group the between-group comparisons are exploratory. The constant 1500 newton peak force does not capture the variation in ground reaction forces across running speeds and body masses, the three tested orientations approximate but do not span the continuous spectrum of real foot strike angles, and each material was represented by a single density, so material and density effects could not be separated. Foam cell structure was not characterised, and stack height was compared between two shoe models whose other differences cannot be fully disentangled. Future work, the authors suggest, should test whether the orientation effects translate into measurable biomechanical changes during running, examine loading frequencies given the viscoelastic nature of midsole foams, extend cyclic testing to see whether orientation effects persist as foam ages, and replicate across multiple shoes of the same construction. For now, the message for the footwear industry is clear: a shoe tested only straight down may not behave the way it does when a runner lands on the heel or the forefoot, and multi-orientation testing offers a more honest picture of how midsoles actually cushion the millions of angled impacts that running delivers.

Subject of Research: Effects of loading orientation on the mechanical cushioning properties of running shoe midsoles

Article Title: Mechanical cushioning properties of running shoe constructions across loading orientations

Article References: Scherrer, D., Legg, K. A., Rogers, C. W., Gottschall, J. S., & Cochrane, D. J. (2026). Mechanical cushioning properties of running shoe constructions across loading orientations. Sports Engineering, 29(2), Article 33. https://doi.org/10.1007/s12283-026-00567-2

Image Credits: AI Generated

DOI: 10.1007/s12283-026-00567-2

Keywords: running shoes, midsole, cushioning, EVA, PEBA, foot strike, stiffness, energy return, biomechanics, mechanical testing, stack height, sports engineering