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Updated: May 26, 2026

Induction and Assessment of Exertional Skeletal Muscle Damage in Humans
Published on: December 11, 2016
Short intervals between sets and individuality of muscle damage response
Marco Machado1, Rafael Pereira, Jeffrey M Willardson
1Laboratory of Human Movements Studies, University Foundation of Itaperuna (FUNITA), Itaperuna, Brazil. jmwillardson@eiu.edu
Abstract:
This study examined creatine kinase (CK) activity after resistance exercise sessions in subjects classified as high (HiR), medium (MeR), or low responders (LoR). Two resistance exercise sessions were performed that each involved 4 sets of the biceps curl at 85% of a 1 repetition maximum (1RM) and either 1- or 3-minute rest intervals between sets. High responders and MeR demonstrated significantly greater CK activity after the 1-minute session vs. the 3-minute session. Therefore, the HiR and MeR subjects exhibited less tolerance to resting 1 minute between sets, whereas the CK activity was not significantly different between rest intervals for the LoR subjects. The application of these findings indicates the need to vary the length of the rest interval between sets with the understanding that individuals exhibit varying recuperative abilities and some might be less tolerant of shorter rest intervals between sets.
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