Fig. 4

Absolute (a) and relative (b, c) changes in maximal isometric voluntary contractions of the quadriceps femoris muscle following single sessions of neuromuscular electrical stimulation preceded by low-level laser irradiation or sham low-level laser intervention. b In percent changes in comparison to baseline. c In the values normalized on baseline from two interventions (LLLT and sham-LLLT) combined (Z-score). MVC – maximal isometric voluntary contraction; LLLT – neuromuscular electrical stimulation preceded by low level laser irradiation; sham-LLLT – neuromuscular electrical stmulation preceded by sham low level laser intervention; 0 h – immediately post intervention; 24, 48, 72, 96 h – subsequent hours post intervention; values are means ± SE (a and b) and means (c); a main time effect present (p < 0.0001); ^*difference significant (p < 0.05), as compared to baseline (within the same intervention); ^†difference significant (p < 0.05) for 24 h, as compared to 0 h (within LLLT intervention); ^‡difference significant (p < 0.05) for 96 h, as compared to 0 h (within LLLT intervention). b and c main time effect present (p < 0.01); ^*difference significant (p < 0.05), as compared 0 h (within the same intervention); ^# difference significant (p < 0.05) for 96 h, as compared to 48 and 72 h (within sham-LLLT intervention)