Table 3.

Heart function of 56-wk-old mdx mice with free access to a running wheel or held in cage sedentary conditions for 1 yr

	Sedentary (n = 11)	Runner (n = 9)
Heart mass, mg	147 ± 3	174 ± 8*
Relative heart mass, mg/g body wt	4.5 ± 0.1	4.8 ± 0.2
Heart rate, beats/min	349 ± 18	325 ± 32
Interventricular septum (diastole), mm	0.96 ± 0.04	0.94 ± 0.05
LV internal diameter (diastole), mm	3.3 ± 0.2	4.1 ± 0.07*
LV free wall (diastole), mm	1.0 ± 0.09	1.0 ± 0.10
LV internal diameter (systole), mm	2.3 ± 0.17	2.8 ± 0.01*
Fractional shortening, %	33 ± 3	31 ± 2
End-diastolic volume, ml	0.10 ± 0.01	0.17 ± 0.01*
End-systolic volume, ml	0.04 ± 0.01	0.06 ± 0.01*
Stroke volume, ml	0.06 ± 0.01	0.11 ± 0.01*
Ejection fraction, %	67 ± 4	65 ± 4
Cardiac output, l/min	0.02 ± 0.00	0.04 ± 0.01*

Values are means ± SE; n, number of samples. LV, left ventricle.

^*Significantly different from sedentary (P < 0.05).