The 30-15 Intermittent Fitness Test Provides Superior Sport-Specific Sensitivity to Treadmill Testing in Elite Female Footballers

Overview

This study compares the acute aerobic, metabolic, and threshold-related physiological responses elicited by the 30-15 Intermittent Fitness Test (30-15IFT) and a treadmill-based incremental running test in elite female football players. Using a randomized crossover design, all participants completed both testing protocols with a 48-hour recovery period. Outcomes included maximal oxygen uptake, maximal running speed, heart rate responses, lactate-derived thresholds, metabolic tolerance indices, and recovery markers.

Laboratory-based treadmill tests are commonly used to assess aerobic capacity in football players; however, they lack sport-specific characteristics such as intermittent running, accelerations, and changes of direction. The 30-15 Intermittent Fitness Test (30-15IFT) has been proposed as a more ecologically valid field-based alternative. Twenty-seven elite female football players competing in the Turkish Women's Super League completed both the 30-15IFT and a standardized treadmill incremental protocol in a randomized crossover design. Tests were separated by 48 hours and performed under controlled environmental conditions. Physiological variables including VO₂max, maximal running speed, maximal heart rate, respiratory exchange ratio, lactate-derived thresholds (OBLA), metabolic load-dependent tolerance, and post-exercise recovery markers were assessed using breath-by-breath gas analysis, heart rate monitoring, and capillary blood lactate sampling. The study aims to determine whether the 30-15IFT elicits more sensitive and sport-specific physiological responses compared with treadmill testing, thereby supporting its use in performance monitoring and individualized training prescription in elite women's football.