Changes in strength and aerobic performance by concurrent training in under-19 soccer players

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Journal Article

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Fitness, Exercise testing, Training load, Team sport, Football association


Background: This study aimed to determine: 1) the changes in the physical conditioning of under-19 soccer players, 2) the effects of strength training using resistance executed as a function of the speed of a Smith machine bar, 3) relationships between heart rate (HR) values recorded during training and competition and changes in players' physical conditioning.

Methods: Nineteen field players from a team in the U-19 Spanish first division participated in the study. Changes in jump ability (CMJ, CMJL), bar movement speed in a loaded full squat (FSL), sprint time over 30m (T10, T20, T30, T10-20,T10-30, T20-30), and maximal aerobic speed (MAS) were evaluated three times (E1, E2, E3) during the fourth months studied. Players' HR during practices and matches were recorded. Improvements in MAS, application of strength in CMJ, CMJL, and FSL were reported, while the players significantly worsening their sprint times.

Results: No significant relationships were found between HR values and changes in players' physical conditioning. Changes in sprint times (T30 and T10-30) were correlated with changes in bar speed for the FS60kg (r = 0.53-0.64, p < 0.05) and volume of strength training performed (r = 0.53-0.59, p < 0.05). These improvements in strength did not induce expected improvement in sprint time, possibly due to the interference effect between concurrent aerobic and strength training.

Conclusions: The results suggests that improved ability to accelerate could be related to improvements in loaded full squats moving at speed near 1m.s-1, and the inhibitor effect obtained shows the importance of monitoring the intensity of aerobic training.

Source Publication

International SportMed Journal

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