Below is a concise template-style explanation you can use to document why each metric was chosen, what it targets, its theoretical/empirical basis, and the key assumptions and limits.
1) Metric name (e.g., Sprinting distance > 22.5 km/h)
- What it targets: Measures high-intensity running load associated with maximal efforts and repeated-sprint stress.
- Why chosen (theoretical/empirical basis): High-speed efforts correlate with acute metabolic and neuromuscular load and with injury risk in team sports (see Abbott et al., 2018; neuromuscular fatigue literature). Clubs use speed thresholds to quantify match demands and plan conditioning.
- Assumptions and limits: Assumes a universal threshold (22.5 km/h) meaningfully maps to ‘sprint’ for all players — but optimal thresholds may vary by sex, age, position, and measurement system. GPS inaccuracies, sampling frequency, and different tracking systems affect values. Use individualized thresholds or validate population cutoffs for women’s cohorts where possible.
2) Metric name (e.g., Acute:Chronic Workload Ratio (ACWR))
- What it targets: Detects sudden spikes in workload (acute) relative to a longer-term baseline (chronic), which are associated with elevated injury risk.
- Why chosen: Empirical studies in football show workload spikes often precede injuries; ACWR provides a simple operational rule for load management.
- Assumptions and limits: ACWR’s predictive power is debated; different smoothing windows and computation methods alter outcomes. Most evidence comes from men’s or mixed samples—validate parameters for women. It does not capture all risk factors (sleep, menstrual cycle, previous injury) and should be combined with clinical judgment.
3) Metric name (e.g., Expected Goals (xG) per 90)
- What it targets: Quality of shooting opportunities, disentangling chance creation from finishing variance.
- Why chosen: xG models, built from historical shot data, improve evaluation of attacking performance beyond raw goals by estimating probability of scoring given shot context.
- Assumptions and limits: Typically trained on men’s data; shot-location and context effects may differ in women’s football (shot speed, defensive spacing). Model features and calibration should be re-trained or recalibrated on women’s datasets to avoid bias.
4) Metric name (e.g., Defensive Action Value or Value Added)
- What it targets: Quantifies the defensive contribution of actions (tackles, interceptions, pressures) to preventing expected goals or possession turnover.
- Why chosen: Moves beyond counting events to estimating impact on opponent scoring probability or transition risk using event and spatio-temporal models.
- Assumptions and limits: Requires high-quality event and tracking data; models assume historical mappings from actions to outcomes generalize across teams and sex. Tactical differences (pressing intensity, defensive compactness) may demand model adjustment for women’s competitions.
5) Metric name (e.g., Injury risk probability from wearable + wellness model)
- What it targets: Individualized probability of sustaining an injury in a given time window to inform preventive interventions.
- Why chosen: Combines multiple inputs (GPS loads, sleep, subjective wellness, menstrual cycle tracking, prior injuries) to capture multifactorial risk more holistically than single metrics.
- Assumptions and limits: Model validity depends on representative training data and careful handling of sensitive inputs (privacy). Probabilities are conditional estimates, not certainties; threshold selection balances false negatives vs false positives and should reflect clinical priorities for women athletes.
6) Metric name (e.g., Passing network centrality)
- What it targets: Tactical influence and involvement in ball progression; identifies structurally important players and patterns of play.
- Why chosen: Network metrics summarize team structure and can reveal roles not evident from counts (e.g., a node that connects phases).
- Assumptions and limits: Interpretation depends on consistent event coding and tactical context. Differences in playing style (positional fluidity, formation) between competitions require cautious cross-team comparisons.
7) Metric name (e.g., Model calibration — Brier score / calibration plots)
- What it targets: How well predicted probabilities match observed outcomes (reliability of risk scores).
- Why chosen: A perfectly discriminative model is still unsafe if its probability forecasts are miscalibrated; calibration matters for decision thresholds in clinical or training contexts.
- Assumptions and limits: Calibration must be assessed in the target population (women’s leagues) and monitored over time as distributions shift.
Guidance for use of the record
- Tie each metric to a decision: state the operational action that follows a given threshold (e.g., reduce training load by X% if ACWR > 1.5 for two consecutive weeks).
- Note data provenance and tracking system: record device type, sampling rate, and data cleaning steps.
- Document validation evidence: report whether the metric or model was trained/tested on women’s data, sample sizes, and out-of-sample performance.
- List privacy/consent considerations for biometric data and any regulatory constraints.
Short closing note
Explicitly recording the rationale and assumptions for each metric makes analytics transparent, helps avoid misapplication (especially when porting models from men’s to women’s football), and supports ongoing validation as more women-specific data becomes available.
Selected references
- Gudmundsson, J. & Horton, M. (2017). Spatio-temporal analysis of team sports. ACM Computing Surveys.
- Abbott, W. et al. (2018). High-speed running and sprinting in team sports: Methods and applications. Sports Medicine.
- Dallinga, J. M. et al. (2020). Sex differences in sports injuries: systematic review.