Impact Of Exercise Intensity And Resting Intervals During Resistance Exercise On Acute Sparc Secretion In Healthy Young Males: A Pilot Study

Abstract

PURPOSE: Recently, it is going noteworthy that an exercise-induced novel myokine, secreted protein acidic and rich in cysteine (SPARC) has the potential to prevent colon cancer. Moreover, regular resistance exercise (RE) has been known to reduce the mortality risk of cancer. From these points of view, RE might prevent colon tumorigenesis via increasing SPARC, while it is unclear whether resistance exercise can promote SPARC secretion in human. Thus, the purpose of this study was to investigate the both effects of exercise intensity and duration of rest interval between exercise sets on acute response of RE-induced SPARC secretion. METHODS: We designed two experiments in this study. In study 1, 7 subjects completed three experiments in a random order. They performed two RE at both 70% (High) and 35% (Low) of the individual’s one repetition maximum (1-RM), and stayed rest condition without RE (Rest). The RE consisted of 8 kinds of exercise (double arm curl, shoulder press, double knee extension, chest press, lat-pull down, triceps press down, parallel squat, and seated rowing), for 3 sets of 7 repetitions. We recruited different 7 subjects in study 2, and let them conduct three experiments in a random order: RE (the same 8 kinds of exercise as described in study 1, 16 repetitions × 3 sets at 50% 1-RM) with long inter-set rest interval (LIE, 150 s), RE with short inter-set rest interval (SIE, 50 s), and rest with no-exercise (NE). Blood samples were obtained before, immediate after, and 1h after RE in both study. RESULTS: In study 1, serum SPARC concentration immediately after RE was significantly increased from baseline in High trial (P < 0.05), and that level was significantly higher than those in Rest and Low trials (P < 0.05, in both). In study 2, serum SPARC level immediately after RE in SIE trial significantly elevated compared with baseline (P < 0.05), and the increase was also significantly higher than NE trial (P < 0.05). However, the elevated SPARC concentrations in both High and SIE trials were swiftly returned to baseline within 1 h after RE. CONCLUSIONS: Our findings indicate that RE can induce temporally SPARC secretion. It is also conceivable that increasing exercise load and/or shortening rest intervals between exercise sets during RE might enhance SPARC production.