Maximal voluntary contraction force, SR function and glycogen resynthesis during the first 72 h after a high-level competitive soccer game

The aim of this study was to examine maximal voluntary knee-extensor contraction force (MVC force), sarcoplasmic reticulum (SR) function and muscle glycogen levels in the days after a high-level soccer game when players ingested an optimised diet. Seven high-level male soccer players had a vastus lateralis muscle biopsy and a blood sample collected in a control situation and at 0, 24, 48 and 72 h after a competitive soccer game. MVC force, SR function, muscle glycogen, muscle soreness and plasma myoglobin were measured. MVC force sustained over 1 s was 11 and 10% lower (P < 0.05) after 0 and 24 h, respectively, compared with control. The rate of SR Ca²⁺ uptake at 800 nM [Ca²⁺]_free was lower (P < 0.05) after 0 h (2.5 μmol Ca²⁺ g prot⁻¹ min⁻¹) than for all other time points (24 h: 5.1 μmol Ca²⁺ g prot⁻¹ min⁻¹). However, SR Ca²⁺ release rate was not affected. Plasma myoglobin was sixfold higher (P < 0.05) immediately after the game, but normalised 24 h after the game. Quadriceps muscle soreness (0–10 VAS-scale) was higher (P < 0.05) after 0 h (3.6), 24 h (1.8), 48 h (1.1) and 72 h (1.4) compared with control (0.1). Muscle glycogen was 57 and 27% lower (P < 0.001) 0 and 24 h after the game compared with control (193 and 328 vs. 449 mmol kg d w⁻¹). In conclusion, maximal voluntary contraction force and SR Ca²⁺ uptake were impaired and muscle soreness was elevated after a high-level soccer game, with faster recovery of SR function in comparison with MVC force, soreness and muscle glycogen.