6533b7d6fe1ef96bd1266802

RESEARCH PRODUCT

Effects of exhaustive stretch-shortening cycle exercise on muscle blood flow during exercise

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Aim:  The influence of exhaustive stretch-shortening cycle exercise (SSC) on skeletal muscle blood flow (BF) during exercise is currently unknown. Methods:  Quadriceps femoris (QF) BF was measured in eight healthy men using positron emission tomography before and 3 days after exhaustive SSC exercise. The SSC protocol consisted of maximal and submaximal drop jumps with one leg. Needle biopsies of the vastus lateralis muscles were taken immediately and 2 days after SSC for muscle endothelial nitric oxide synthase (eNOS) and interleukin-1-beta (IL-1β) mRNA level determinations. Results:  All subjects reported subjective muscle soreness after SSC (P < 0.001), which was well in line with a decrease in maximal isometric contraction force (MVC) and increase in serum creatine kinase activity (CK) (P = 0.018). After SSC muscle BF was 25% higher in entire QF (P = 0.043) and in its deep and superficial muscle regions, whereas oxygen uptake remained unchanged (P = 0.893). Muscle biopsies revealed increased IL-1β (30 min: 152 ± 75%, P = 0.012 and 2 days: 108 ± 203%, P = 0.036) but decreased or unchanged eNOS (30 min; −21 ± 57%, P = 0.050 and 2 days: +101 ± 204%, P = 0.779) mRNA levels after SSC. Conclusion:  It was concluded that fatiguing SSC exercise induces increased muscle BF during exercise, which is likely to be associated with pro-inflammatory processes in the exercised muscle.