Ehsani Ali A, Spina Robert J, Peterson Linda R, Rinder Morton R, Glover Kathryn L, Villareal Dennis T, Binder Ellen F, Holloszy John O
Section of Applied Physiology, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
J Appl Physiol (1985). 2003 Nov;95(5):1781-8. doi: 10.1152/japplphysiol.00194.2003. Epub 2003 Jul 11.
To determine the mechanisms underlying increased aerobic power in response to exercise training in octogenarians, we studied mildly frail elderly men and women randomly assigned to an exercise group (n = 22) who participated in a training program of 6 mo of physical therapy, strength training, and walking followed by 3 mo of more intense endurance exercise at 78% of peak heart rate or a control sedentary group (n = 24). Peak O2 consumption (V(O2 peak)) increased 14% in the exercise group (P < 0.0001) but decreased slightly in controls. Training induced 14% increase (P = 0.027) in peak exercise cardiac output (Q), determined via acetylene re-breathing, and no change in arteriovenous O2 content difference. The increase in Q was mediated by increases in heart rate (P = 0.009) and probably stroke volume (P = 0.096). Left ventricular stroke work also increased significantly. In the men, the increase in V(O2 peak) was exclusively due to a large increase in peak Q (22%). In the women, the gain in V(O2 peak) was due to small increases in Q and O2 extraction from skeletal muscles. Pulse pressure normalized for stroke volume and arterial elastance during peak effort did not change with training. Controls showed no changes. The results suggest that, although frail octogenarians have a diminished capacity for improvement in aerobic power in response to exercise training, this adaptation is mediated mostly by an increase in Q during peak effort. Furthermore, Q likely plays a greater role in the adaptive increase in V(O2 peak) in old men than old women.
为了确定八旬老人运动训练后有氧能力增强的潜在机制，我们研究了轻度虚弱的老年男性和女性，他们被随机分为运动组（n = 22）和久坐对照组（n = 24）。运动组参加了为期6个月的物理治疗、力量训练和步行训练计划，随后进行3个月强度更大的耐力运动，运动强度为心率峰值的78%；对照组则保持久坐。运动组的峰值耗氧量（V（O2峰值））增加了14%（P < 0.0001），而对照组略有下降。通过乙炔再呼吸法测定，训练使运动峰值心输出量（Q）增加了14%（P = 0.027），动静脉氧含量差无变化。Q的增加是由心率增加（P = 0.009）和可能的每搏输出量增加（P = 0.096）介导的。左心室每搏功也显著增加。在男性中，V（O2峰值）的增加完全是由于峰值Q大幅增加（22%）。在女性中，V（O2峰值）的增加是由于Q和骨骼肌氧摄取量的小幅增加。运动峰值时经每搏输出量和动脉弹性校正的脉压在训练后没有变化。对照组无变化。结果表明，尽管体弱的八旬老人对运动训练的有氧能力改善能力有所下降，但这种适应性变化主要是由运动峰值时Q的增加介导的。此外，Q在老年男性V（O2峰值）的适应性增加中可能比老年女性发挥更大的作用。
