Creatine Kinase and Lactate Dehydrogenase Responses After Upper-Body Resistance Exercise With Different Rest Intervals

The purpose of the current study was to compare serum creatine kinase (CK) and lactate dehydrogenase (LDH) concentrations at multiple time points after resistance exercise sessions that incorporated different rest intervals between sets and exercises. Twenty untrained men (18.65+/-0.49 years, 68.30+/-7.98 kg, and 174.4+/-4.80 cm) performed 2 resistance exercise sessions (i.e., 3 sets with 80% 1 repetition maximum for 5 upper-body exercises) with either 1-minute (SEQ1) or 3-minute (SEQ3) rest between sets and exercises. For each session, CK and LDH concentrations were measured before exercise (PRE) and 24, 48, and 72 hours after exercise (24P, 48P, and 72P). Subjects lifted a 24% greater (p<0.05) volume load during SEQ3 than during SEQ1. Within SEQ1, significant differences in CK concentrations were demonstrated between most time points, except between 24P and 72P. Similarly, within SEQ3, significant differences in CK concentrations were demonstrated between most time points, except between 24P and 72P and between 48P and 72P. The CK concentrations were highest at 48P for both sessions. When the CK concentrations were compared between SEQ1 and SEQ3, no significant differences were demonstrated at any time point. Within SEQ1, a significant difference in LDH concentration was demonstrated between 48P and 72P. Within SEQ3, significant differences in LDH concentrations were demonstrated between PRE and 24P and between PRE and 48P. The LDH concentrations were highest at 72P for SEQ1 and at 24P for SEQ3. When the LDH concentrations were compared between SEQ1 and SEQ3, no significant differences were demonstrated at any time point. These results suggest that muscle damage was similar between rest intervals; however, the volume load completed to induce the muscle damage was significantly greater when 3-minute rest intervals were employed. Therefore, when considered relative to the volume load completed, 1-minute rest intervals during resistance exercise may invoke greater muscle damage.