Time course and fibre type‐dependent nature of calcium‐handling protein responses to sprint interval exercise in human skeletal muscle

Sprint interval training (SIT) causes fragmentation of the skeletal muscle sarcoplasmic reticulum Ca2+ release channel, ryanodine receptor 1 (RyR1), 24 h post‐exercise, potentially signalling mitochondrial biogenesis by increasing cytosolic [Ca2+]. Yet, the time course and skeletal muscle fibre type‐specific patterns of RyR1 fragmentation following a session of SIT remain unknown. Ten participants (n = 4 females; n = 6 males) performed a session of SIT (6 × 30 s ‘all‐out’ with 4.5 min rest after each sprint) with vastus lateralis muscle biopsy samples collected before and 3, 6 and 24 h after exercise. In whole muscle, full‐length RyR1 protein content was significantly reduced 6 h (mean (SD); −38 (38)%; P