Validity in Strength and Conditioning

Introduction

This module focuses on validity and its importance in strength and conditioning. We will explore:

Definition of validity.
Importance of validity for strength and conditioning coaches.
Methods for assessing validity.
Designing validation studies.

What is Validity?

Validity is the degree to which a test or instrument measures what it intends to measure. It determines the accuracy of a measurement in representing what we are trying to test.

Example: How accurately does a test measure an athlete's maximum strength?

Types of Validity

1. Logical Validity

The degree to which a measure obviously involves the performance being tested.
Example:
- One-repetition maximum (1RM) test for maximum strength: It logically assesses maximum strength by directly measuring the force an athlete can exert.
- Sprint testing measures speed over a specific distance, providing an indication of the athlete's sprint ability.
- Single leg balance test assesses an athlete's ability to maintain balance in a static environment.

2. Content Validity

The degree to which a test adequately samples what was covered in a course (primarily used in education).
Example: Ensuring tests in a course adequately sample from all content learned.
Less relevant in strength and conditioning, but may apply to questionnaire work.

3. Criterion Validity

The degree to which scores on a test or measurement are related to a recognized standard or criterion.
Most important for strength and conditioning coaches when assessing equipment and tests.
Split into two subtypes:
- Concurrent Validity
- Predictive Validity

Concurrent Validity

Whether a measurement instrument is compared to a criterion using recordings made at the same time and whether they give approximately equal values.
Commonly encountered in strength and conditioning literature.
Involves measurement.
Example: Comparing a velocity measurement device or jump mat to a gold standard like a force plate to ensure consistent jump height values.

Predictive Validity

The degree to which scores of a variable can accurately predict criterion scores.
Example: Assessing whether scores from the Functional Movement Screen (FMS) can predict injury in sports.
Assessed through correlation or linear regression.

4. Construct Validity

The degree to which a test measures a hypothetical construct.
A hypothetical construct is a non-directly observable human characteristic or a known group difference.
Example: Wellness questionnaires using Likert scales to assess an athlete's overall wellness based on training load changes.