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J Sports Sci. 2018 Dec;36(24):2856-2864. doi: 10.1080/02640414.2018.1480052. Epub 2018 May 30.

Effect of different inter-repetition rest intervals across four load intensities on velocity loss and blood lactate concentration during full squat exercise.

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a Centro de Investigación en Rendimiento Físico y Deportivo , Universidad Pablo de Olavide , de Sevilla , España.


This study aimed to analyze the acute effect of inter-repetition rest (IRR) intervals on mechanical and metabolic response during four resistance exercise protocols (REPs). Thirty resistance-trained men were randomly assigned to: continuous repetitions (CR), 10 s (IRR10) or 20 s (IRR20) inter-repetition rest. The REPs consisted of 3 sets of 6, 5, 4 and 3 repetitions against 60, 70, 75 and 80% 1RM, respectively, in the full squat exercise. Muscle fatigue was assessed using: percentage of velocity loss over three sets, percentage of velocity loss against the ~1 m·s-1 load (V1 m·s-1), and loss of countermovement jump (CMJ) height pre-post exercise. Blood lactate was measured before and after exercise. The percentage of velocity loss over three sets and lactate concentration were significantly lower (P < 0.05) for IRR groups compared to CR in all REPs. The CR group showed a significantly higher (P < 0.05) velocity loss against V1 m·s-1 load and loss of CMJ height pre-post exercise than IRR groups in REP against 60% 1RM. In conclusion, both IRR groups produced a significant lower degree of fatigue compared to CR group. However, no significant differences were found in any measured variables between IRR configurations.


Resistance training; cluster configurations; fatigue; metabolic stress

[Indexed for MEDLINE]

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