A methodological proof-of-concept of the teeter-totter effect
Bibliographic record
Abstract
The Nike Vaporfly 4% (VP4) shoe is popular due to its unique design and reported performance benefits. However, the underlying mechanisms responsible for the improvements remain unclear. One proposed mechanism is the teeter-totter effect. This study aimed to 1) experimentally test the teeter-totter theory by estimating the teeter-totter moment (MTT) in the VP4 compared to a flat shoe (CONTROL) and 2) quantify the change in the anterior-posterior position of the centre of pressure (Δxa-p) in the VP4 compared to the CONTROL. Plantar pressures and high-speed video were recorded from 15 runners in two shoe conditions. The VP4 generated a larger propulsion moment, MP, (∫MPdt = 90.46 ± 38.87 Nms; p < 0.001, d = 1.95), suggesting the presence of an MTT in the VP4 (∫MTTdt = 57.16 ± 24.35 Nms) when compared to the CONTROL (∫MPdt = 33.30 ± 14.52 Nms). Δxa-p was greater in the VP4 (Δxa-p = 9.48 ± 6.08 mm; p < 0.001, d = 2.07) compared to the CONTROL (Δxa-p = 0.54 ± 0.67 mm). This study provides a methodological proof-of-concept for the teeter-totter theory. The findings highlight the possibility of a teeter-totter effect resulting in greater heel propulsion while running in an AFT shoe construction, assuming a constant muscle moment and pivot point.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".