Author(s): MYKLEBUST, H., MONSLAUP, T.L., BYBERG, M., Institution: UNIVERSITY OF STAVANGER, Country: NORWAY, Abstract-ID: 2730

INTRODUCTION:
Readiness refers to an individual player’s physical and psychological preparedness to train and compete [1], and it is central for in-season decision-making regarding adjustments of training load in football. When monitoring readiness in female players, Beato et al. [2] recommend integrating both subjective questionnaires and objective indicators, such as counter-movement jumps (CMJ). The objective measure of low-frequency fatigue (LFF) has been observed after matches in young male elite soccer players, and such measures have been suggested as an additional objective tool for monitoring post-match fatigue [3]. This study aimed to examine LFF and CMJ following matches and strength-training sessions in female footballers.
METHODS:
A descriptive repeated-measures design was used, including 28 female footballers from two different teams in the 2nd and 3rd tiers of Norwegian football. The players completed LFF (“Powerdex” by Myocene, Liège – Belgium) and CMJ (VALD ForceDecks) tests prior to, immediately after and one day after one (n=6) to three (n=11) matches. Additionally, 16 players, including 4 players not starting the matches, performed LFF and CMJ prior to, immediately after and one day after one (n=3) to three (n=10) strength sessions. LFF from the dominant thigh and the best of 3 CMJ trials were used for statistical analysis. A repeated measures ANOVA was performed between time points. Pre-match measures from players with more than one match were used for calculating the typical error (TE), which was further used to quantify the effect size (ES=mean changes / TE).
RESULTS:
On average, pre match LFF was 73.4 arbitrary Powerdex units (SD=6.9, n=53) and CMJ height was 30.6 cm (SD=3.1, n=56), with a within-athlete TE of 3.3 units (n=18) and 0.8 cm (n=19). Powerdex values were reduced by 1.8 units (SD=5.2, n=52, p=0.014, ES=0.5) after matches and by 5.7 units (SD=5.3, n=36, p < 0.001, ES=1.7) after lower-body strength sessions. Testing one day after showed increases of similar magnitude (match changes M=1.7, SD=4.0, n=45, p=0.008, ES=0.5; strength changes M=6.2, SD=5.8, n=30, p < 0.001, ES=1.9).
CMJ height showed no significant differences at any post-match time point, but immediately after the strength session CMJ height was reduced by 1.0cm (SD=1.7, n=35, p=0.002, ES=1.3). CMJ performance returned to baseline after one day (mean changes from post-session=0.7cm, SD=1.5, n=29, p=0.015, ES=0.9).
CONCLUSION:
Our study of female footballers aligns with the findings of Tito et al. (2025) in young male players, indicating that football matches induce fatigue detectable by LFF, but not by CMJ jump height. Furthermore, compared with football matches, a lower-body strength session produced approximately three times greater LFF, which was also detectable using CMJ. However, all values returned to baseline within a day.

References:
1 Gabbet 2017 https://doi.org/10.1136/bjsports-2016-097298
2 Beato 2024 https://doi.org/10.1123/ijspp.2023-0405
3 Tito 2025 https://doi.org/10.1055/a-2456-215