Key result
Submaximal fitness test exercise heart rate demonstrated a large inverse association (r = -0.55) with 5-minute-30-second time-trial mean velocity changes over an 8-week preseason in female football players.
Why the study?
To evaluate the within-athlete sensitivity, validity, and dose-response relationships of exercise heart rate from a submaximal fitness test as a proxy measure of cardiorespiratory fitness.
Observational (n=25)
No
Effect estimate: r = -0.55 (95% CI -0.71 to -0.31)
SMFT HRex is a sensitive and valid tool to evaluate preseason cardiorespiratory-fitness changes in female football players, addressing a gap in research on female athletes.
SMFT HRex may track fitness changes in female footballers; extends male data but leaves open prospective validation before adoption.
PURPOSE: To evaluate the within-athlete sensitivity, validity, and dose-response relationships of exercise heart rate (HRex) from a submaximal fitness test (SMFT) as a proxy measure of cardiorespiratory fitness. METHODS: This study follows an observational, repeated-measures design. Twenty-five trained female football players' training loads (GPS and HR metrics) were collected throughout an 8-week preseason period. A 4-minute continuous-fixed SMFT protocol was administered weekly to evaluate HRex. A running time-trial assessment was conducted in weeks 2 and 8 to calculate mean velocity (5-min-30-s time-trial mean velocity) as a proxy measure of cardiorespiratory fitness. SMFT HRex measurement properties were determined via within- and between-athletes correlations and linear mixed models. RESULTS: The overall preseason change in SMFT HRex derived from weekly repeated measures was -4.7% points (90% CIs, -3.9 to -5.6). The association between SMFT HRex and 5-minute-30-second time-trial mean velocity changes was large (-0.55), with 90% CIs ranging from negative moderate to negative very large magnitudes (-0.31 to -0.71). A 1% point decrease in SMFT HRex corresponded to an increase in 5-minute-30-second time-trial mean velocity of 0.13 (90% CIs, 0.03-0.24) km·h-1. Within-athlete correlations between training loads and SMFT HRex demonstrated moderate inverse relationships with external-load parameters (-0.39 to -0.47) and small inverse relationships with HR-based internal metrics (-0.25 to -0.29). Accumulated high- and very high-speed running throughout the entire preseason showed consistent inverse dose-response relationships with SMFT HRex (moderate and large, respectively), while all other load measures displayed unclear associations. CONCLUSIONS: SMFT HRex is a sensitive and valid tool to evaluate preseason cardiorespiratory-fitness changes in female football players.
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MacKenzie et al. (2025) conducted an observational in Healthy female football players (n=25). Submaximal fitness test (SMFT) exercise heart rate (HRex) vs. 5-minute-30-second time-trial mean velocity was evaluated on Association between SMFT HRex and 5-minute-30-second time-trial mean velocity changes (r = -0.55, 95% CI -0.71 to -0.31). Submaximal fitness test exercise heart rate demonstrated a large inverse association (r = -0.55) with 5-minute-30-second time-trial mean velocity changes over an 8-week preseason in female football players.
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