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Central, peripheral, and generalized adaptations in cardiac rehabilitation

University of British Columbia

The purpose of this study was to investigate whether central adaptations are responsible for. a transfer of fitness to untrained limbs in 13, 9 and 7 CAD/post-MI patients exercising in a walk/jog (WJ) (Legs only) , an aerobic circuit (CT) (arm+legs) program, and a low exercise intensity control group (LC) respectively, for 6 months. Graded exercise tests to determine maximum arm and cycle (leg) aerobic capacity (VO₂peak) and ventilatory threshold (VT) was measured using a SensorMedics Metabolic Measurement Cart, and an arm ergometer and electronically braked cycle ergometer, respectively. Left ventricular (LV) function and absolute volumes (calculated by non-geometric methods) during cycle ergometry were measured by gated bloodpool radionuclide angiograms (RNA). Cycle maximal aerobic capacity (VO₂peak) increased in CT and WJ: 1.96. ± 0.58 to 2.17 ± 0.70 (P<.01) vs. 1.93 ± 0.51 to 2.22 ± 0.54 (P<.004) l-min-1, respectively. Arm VO₂peak increased from 1.32 ± 0.42 to 1.52 ± 0.47 (P<.001) vs. 1.35 ± 0.32 to 1.45 ± 0.34 1-min⁻¹ (P<.01)for the CT and WJ groups, respectively. In both exercise with arm and legs, VT was increased in the WJ and CT groups, but the greatest changes were for VT as expressed as absolute VO₂. Both arm and leg VO₂peak data were correlated with arm and leg VT. The LC group demonstrated no changes in VO₂peak or VT for arms or legs. Peak LV Ejection Fraction (LVEFpeak) increased more in the WJ group than the CT group: 53.3 ± 0.11 to 64.8 ± 0.10 vs. 50.7 ± 0.12 to 55.3 ± 0.11% (P<.02), as did Ejection Rate, and LVESV (changes pre vs. post ; 0.52 vs. -0.13 EDV/sec, and -21.59 vs. 6.89 ml, respectively (P<.05). Cardiac output and stroke volume (SV) increased significantly at rest and exercise in the WJ and CT groups, but Peak total peripheral resistance (TPR) however was related to SV and LVESV (r=-.69 P< .003, r=-.42, P<.05), obscuring apparent intrinsic cardiac adaptations. In addition, neither group demonstrated alterations in body composition and blood lipids as a result of training, despite significant increases in functional capacity. Results suggest that transfer of fitness to untrained limbs in these patients is due in part, but not solely to increased LV function. TPR or other unidentified contributing factors could still account for these effects.

Text

2010-10-11

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http://hdl.handle.net/2429/29106

Physical Education

University of British Columbia

UBCV

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