Monitoring external and internal training loads in professional soccer players during excessive heat stress
Authors
Alireza Rabbani 1, Filipe Manuel Clemente 2,3,4, Željko Banićević 5, Ivana Banićević 3,4, Rui Miguel Silva 5
1 Sport Science Department, Al Jazira Football Academy, Abu Dhabi, UAE
2 Gdansk University of Physical Education and Sport, 80-336 Gdańsk, Poland
3 Sport Physical Activity and Health Research & Innovation Center (SPRINT), Viana do Castelo, Portugal
4 Escola Superior Desporto e Lazer, Instituto Politécnico de Viana do Castelo, Rua Escola Industrial e Comercialde Nun’Álvares, 4900-347 Viana do Castelo, Portugal
5 HERC- Health, Exercise & Research Center, Dubai, UAE
Phase
The Project
This study aimed to investigate the impact of heat stress on both external and internal training loads in professional soccer players. Elite men soccer players underwent monitoring during training and six match days under both normal (18-24°C) and elevated (34-45 °C) temperature conditions. External load measures included total distance (TD), high metabolic load distance (HMLD), mechanical work (MW), and maximal velocity (MaxV). Internal load was assessed using Edwards’ Training Impulse (TRIMP). Data were analyzed using magnitude-based inferences to determine the effect of heat on performance metrics.
Heat stress significantly altered the training dynamics of professional soccer players, with notable changes in both external and internal load metrics. TD.min-1 decreased with a small magnitude on match day (MD) in heat (ES = -0.55, p < 0.05), and this reduction was even more pronounced on the preceding days, MD-2 (ES = -2.14, p < 0.01) and MD-1 (ES = -1.59, p < 0.01). HMLD.min-1 showed small decrease on MD-2 (ES = -0.23, p > 0.05), and a likely moderate decrease on MD-1 (ES = -1.03, p < 0.01) and MD (ES = -0.78, p < 0.01). MW.min-1 had a large decrease on MD-2 (ES = -1.50, p < 0.01), a moderate decrease on MD-1 (ES = -0.84, p < 0.05), and a small decrease on MD (ES = -0.45, p < 0.05). MaxV showed unclear changes on MD-2 and MD-1, and a small increase on MD in heat (ES = 0.47, p < 0.05). Edwards’ TRIMP increased on MD-2 (ES = 0.77, p < 0.01), MD-1 (ES = 0.73, p < 0.01), and MD (ES = 0.83, p < 0.01).
Heat stress significantly reduced TD, HMLD and MW measures. However, the impact of higher intensity external load was not uniformly affected by heat, as indicated, by the increase in MaxV. Although there was a reduction in external load activity, Edwards’ TRIMP increased during heat stress, indicating a heightened internal load response to the heat conditions.
