Figure 4.

Minute-to-minute results of external chest compression performed by male participants for 30:2 in correlation to physical fitness determined by the heart rate at 75 watts of rowing (HR₇₅). A: compression depth, lower vs. higher HR₇₅: p < 0.001; B: compression rate, lower vs. higher HR₇₅: p < 0.001. Black squares = low HR₇₅; white squares = high HR₇₅. Asterisks indicate significant differences comparing the first minute with the subsequent minutes of compression within each group. *: p < 0.1; **: p < 0.05; ***: p < 0.01. Data are presented as mean ± standard error of mean. For the definition of lower and higher HR₇₅ please refer to the main text.