Author(s): MASUR, L., TRINDADE, G., DÜKING, P., Institution: TECHNISCHE UNIVERSITÄT BRAUNSCHWEIG, Country: GERMANY, Abstract-ID: 1630

INTRODUCTION:
Quantifying aspects of muscular load is relevant to decrease likelihood of overload and injury, yet assessing aspects of muscular load in practice is often impaired due to invasiveness of or time-consumption of available methodologies. Despite the increasing use of infrared-derived skin temperature (Tsk) in elite team sports to assess aspects of muscular load, its longitudinal temporal kinetics and reproducibility across a competitive season remain poorly understood.
METHODS:
Weekly mean hamstring Tsk was obtained from 28 elite soccer players (age: 26.25 ± 4.16 years, height: 182.17 ± 7.63 cm, weight: 79.14 ± 6.78 kg, body fat: 9.00 ± 1.23 %) of the first Portuguese league (Primeira Liga) across one competitive season. Absolute reproducibility was assessed using within-athlete coefficients of variation (CV), and relative reproducibility using intraclass correlation coefficients (ICC [1,1]). Chronic kinetic was examined using a linear mixed-effects model relating current-week Tsk to the previous week’s value, accounting for repeated measurements within athletes.
RESULTS:
Hamstring Tsk demonstrated high absolute within-athlete reproducibility (CV = 2.04%). Relative reproducibility was low (ICC = 0.42), indicating limited stability of rank ordering across athletes. Linear mixed-effects modelling revealed strong temporal persistence, with 84% of the previous week’s Tsk carried forward to the subsequent week (β = 0.84, p < 0.001).
CONCLUSION:
Hamstring skin temperature exhibits high absolute reproducibility but current weeks Tsk is largely affected by previous weeks values. These findings highlight the importance of considering prior Tsk values when interpreting longitudinal Tsk data in athlete monitoring contexts. Future studies should investigate acute and longitudinal effects of different external loads on IRT related parameters such as Tsk.