Jorge M. Celis-Moreno1,2, Jesus L. Lozada-Medina3, Manuel de Jesus Cortina-Nuñez4
1University of Santo Tomas, Faculty of Physical Culture, Sports and Recreation, Bogotá, Colombia
2University of Coimbra, FCDEF, Coimbra, Portugal
3Caribbean University Corporation - CECAR, Faculty of Humanities and Education, Sincelejo, Colombia
4University of Cordoba, Faculty of Education and Humanities Sciences, Montería, Colombia
Internal load of a repeated sprint protocol in pubertal soccer players exposed to moderate altitude
Monten. J. Sports Sci. Med. 2026, 15(2), Ahead of Print | DOI: 10.26773/mjssm.260905
Abstract
This study aimed to describe the performance on a repeated sprint test and assess internal load in youth soccer players at an altitude of 2650 meters. Sixty regional-level soccer players (age 14.1±1.7 years) participated in an RSA 7x30m-20” test. The study assessed height, body mass, fat mass, and Peak Height Velocity (PHV). Heart rate (HR) and blood lactate (LA) levels were monitored, and theoretical fatigue was estimated using the Fatigue Index (FI) and percentage decrement score (Sdec%). Descriptive and correlational statistics were employed for data analysis of anthropometry, performance, and internal load. ANOVA was used to compare different indicators across age groups. Across the sample, HR increased from 109±1 to 181±9 bpm during the protocol. LA mmol/L levels rose significantly at various points: pre-test vs. fourth repetition (t=18.706, p<0.001), fourth repetition vs. post-test (t=9.115, p<0.001), and pre-test vs. post-test (t=33.919, p<0.001). Performance results indicated that the 12-year-old group performed lower than other groups (F=12.261, p<0.001). The study concludes that RSA performance in the 7x30m-20” at 2650 improves with increasing age. LA and estimated fatigue were slightly higher in older participants; however, substantial inter-individual variability was observed in internal load.
Keywords
youth soccer; heart rate, lactate, repeated sprints, sports performance
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