Acute Physiological Responses to High-Intensity Resistance Circuit Training vs. Traditional Strength Training in Soccer Players

SIMPLE SUMMARY: Strength training is a key factor for soccer players, but at amateur levels, it is difficult to apply due to the lack of infrastructure and short training time. In this regard, high-intensity resistance circuit-based training could be a suitable method to solve these issues. Circuit training can improve the cardiorespiratory and metabolic responses while reducing training time by 66%. The effects of circuit training could contribute to improving aerobic fitness and body composition in soccer players. ABSTRACT: The aim of this study was to evaluate and compare the cardiorespiratory and metabolic responses induced by high-intensity resistance circuit-based (HRC) and traditional strength (TS) training protocols. Ten amateur soccer players reported to the laboratory on four occasions: (1) protocol familiarization and load determination; (2) maximal oxygen consumption test; (3) and (4) resistance training protocols (HRC and TS), completed in a cross-over randomized order. In both protocols, the same structure was used (two blocks of 3 sets × 3 exercises, separated by a 5-min rest), with only the time between consecutive exercises differing: TS (3 min) and HRC (~35 s, allowing 3 min of local recovery). To test for between-protocol differences, paired t-tests were applied. Results showed that oxygen consumption and heart rate during HRC were 75% and 39% higher than TS, respectively (p < 0.001). After the training sessions, blood lactate concentration at 1.5, 5 and 7 min and excess post-exercise oxygen consumption were higher in HRC. The respiratory exchange ratio was 6.7% greater during HRC, with no between-group differences found post-exercise. The energy cost of HRC was ~66% higher than TS. In conclusion, HRC training induces greater cardiorespiratory and metabolic responses in soccer players and thus may be a time-effective training strategy.