This study examines how hand grip strength changes over the course of a competitive ice hockey season in elite male and female players.

Hand grip strength is a simple and widely used measure of upper-body strength and functional capacity. It is often used in sports science and clinical settings, but it is unclear whether grip strength remains stable throughout a season or changes depending on training load, match exposure, and fatigue.

In this study, elite ice hockey players from Swedish teams will have their grip strength measured at four timepoints during one season: pre-season, early season, mid-season, and late season. Both dominant and non-dominant hand strength will be assessed using a standardized dynamometer and protocol.

The main purpose is to determine how much grip strength varies within individual players over time and whether a single measurement can be considered representative of a player's true strength level across a season. The study will also evaluate the reliability of grip strength measurements and whether observed changes are large enough to be meaningful in a clinical or performance context.

No intervention is performed, and all measurements are non-invasive and conducted as part of routine testing environments within participating teams.

This is a prospective longitudinal observational cohort study designed to evaluate within-season variability and measurement stability of maximal isometric hand grip strength in elite ice hockey players.

Hand grip strength is widely used as a surrogate marker of upper-limb strength and general neuromuscular capacity. Although its reliability has been well described in clinical and general athletic populations when measured using standardized protocols, limited evidence exists regarding its temporal stability in elite collision sport athletes over an entire competitive season. In particular, it remains unclear whether grip strength behaves as a stable individual characteristic or whether it is influenced by seasonal training load, match congestion, fatigue, or adaptation effects.

The study will include elite male and female ice hockey players recruited from Swedish top-level teams. Participants will undergo repeated standardized grip strength assessments at four predefined timepoints across one competitive season: pre-season baseline, early mid-season, late mid-season, and pre-playoff/end-of-season phase. All measurements will be performed using a calibrated hand dynamometer following a standardized protocol based on established clinical measurement guidelines, including consistent body positioning, handle adjustment, and repeated maximal trials for both dominant and non-dominant hands. Mean values from repeated trials will be used for analysis.

To reduce measurement variability, all testing will be conducted by trained assessors using harmonized instructions across participating teams. Where possible, testing sessions will be scheduled to minimize acute fatigue effects by ensuring a standardized recovery period following matches or high-intensity training sessions.

The primary analytical focus is within-subject variability of grip strength across the season, quantified using measures of dispersion and reliability, including coefficient of variation (CV%), within-subject standard deviation, and intraclass correlation coefficients (ICC). Additional analyses will estimate measurement error (standard error of measurement) and minimal detectable change (MDC95) to determine the smallest meaningful change in grip strength that exceeds expected measurement noise.

Longitudinal changes in grip strength across the season will be assessed using mixed-effects statistical models to account for repeated measures within individuals and potential group-level effects such as sex and playing level.

The study does not involve any interventions, treatment allocation, or experimental manipulation. All assessments are non-invasive and conducted within routine team environments. The findings are intended to inform interpretation of grip strength in athletic monitoring, rehabilitation contexts, and performance evaluation, specifically whether single timepoint measurements can be reliably used for comparison against normative data or whether seasonality must be considered in clinical and performance decision-making.

Inclusion Criteria:

• Contracted elite ice hockey players in participating Swedish teams (SHL, HockeyAllsvenskan, SDHL or equivalent top division)
• Male or female players competing at elite level
• Available for testing at all predefined measurement timepoints across the season
• Able to perform maximal hand grip strength testing
• Provides informed consent

Exclusion Criteria:

• Acute hand or wrist injury at baseline preventing maximal grip strength testing
• Any condition during the study period preventing completion of repeated grip strength assessments
• Inability to participate in all scheduled measurement sessions
• Refusal to participate

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Any data shared with colleagues or collaborating researchers will be fully anonymized or pseudonymized to protect participant privacy in accordance with GDPR regulations. Data transfers will occur under strict confidentiality agreements, and all parties will adhere to applicable data protection laws to ensure the security and privacy of personal information. We will act in accordance with the ethical approval granted by the Swedish Ethical Review Authority (EPM) and comply with all relevant local policies regarding data protection.

From the publication of the protocol and for 10 years thereafter.

Access to individual participant data is typically restricted to authorized researchers involved in the study or approved collaborators under strict confidentiality and data protection agreements.