Table 2: Matrix of bivariable Pearson’s correlation coefficient ( ) values between selected age, physical exercise, obesity, and muscular endurance data.

AgeAny exerciseBMIBody
Fat %
Fat massFat-free mass

Back endurance0.36b−0.22aNS−0.44b−0.45b−0.46b−0.15
Core endurance1.00NSNS−0.47b−0.52b−0.55b−0.26a
Any exercise1.00−0.25a−0.33b−0.28b0.09
Body fat %1.000.96b0.02
Fat mass1.000.28a
Fat-free mass1.00

Key: ; .
Any exercise: self-reported days per week of any physical exercise over the past three months; back endurance: back muscular endurance assessed with the modified Biering Sorensen test(s); core endurance: core muscular endurance assessed with the Plank test(s); BMI: body mass index; NS: not significant.