Proctor David N, Koch Dennis W, Newcomer Sean C, Le Khoi U, Smithmyer Sandra L, Leuenberger Urs A
Noll Physiological Research Center, The Pennsylvania State University, University Park, PA16802-6900, USA.
Med Sci Sports Exerc. 2004 Apr;36(4):623-31. doi: 10.1249/01.mss.0000121951.10417.b5.
To test the hypothesis that leg blood flow and leg O2 extraction during peak exercise are reduced with age in healthy normally active women.
Thirteen younger (20-27 yr) and 12 older (60-71 yr) nonendurance trained women performed graded upright leg cycling to maximum exertion (VO2peak), while leg blood flow (femoral vein thermodilution), cardiac output (acetylene rebreathing), mean arterial pressure (MAP, radial artery), and blood O2 contents were measured.
Peak leg VO2 was 32% lower in the older versus younger women (0.81 +/- 0.06 vs 1.18 +/- 0.10 L x min(-1)) and was correlated with peak systemic VO2 (1.33 +/- 0.1 vs 1.78 +/- 0.1 L x min(-1)) in both groups. Peak leg blood flow and estimated leg vascular conductance were 29% and 38% lower, respectively, in the older women (both P < 0.001). Peak leg blood flow and peak estimated cardiac output were correlated in the older (r2 = 0.51, P = 0.02), but not younger (r2 = 0.10, P = 0.35), group. Estimates of peak systemic and leg arterial-venous O2 difference did not differ between groups (both P > 0.28).
Reduced leg blood flow is a major contributor to the reduced peak systemic VO2 observed in older nonendurance trained women. Diminished leg blood flow during peak exercise in older women, in turn, is due to both central (reduced cardiac output) and peripheral (reduced leg vascular conductance) limitations.
验证健康、正常活动的女性在运动峰值时腿部血流量和腿部氧气摄取量会随年龄增长而降低这一假设。
13名年轻（20 - 27岁）和12名年长（60 - 71岁）未经过耐力训练的女性进行分级直立腿部骑行至最大运动量（VO₂峰值），同时测量腿部血流量（股静脉热稀释法）、心输出量（乙炔重呼吸法）、平均动脉压（MAP，桡动脉）和血液氧气含量。
年长女性的腿部VO₂峰值比年轻女性低32%（0.81 ± 0.06对1.18 ± 0.10 L·min⁻¹），且两组中腿部VO₂峰值均与全身VO₂峰值相关（1.33 ± 0.1对1.78 ± 0.1 L·min⁻¹）。年长女性的腿部血流量峰值和估计的腿部血管传导率分别低29%和38%（P均<0.001）。在年长组中，腿部血流量峰值与估计的心输出量峰值相关（r² = 0.51，P = 0.02），而年轻组中无此相关性（r² = 0.10，P = 0.35）。两组间全身和腿部动脉 - 静脉氧气分压差峰值估计值无差异（P均>0.28）。
腿部血流量减少是年长的未经过耐力训练女性全身VO₂峰值降低的主要原因。反过来，年长女性运动峰值时腿部血流量减少是由于中枢（心输出量减少）和外周（腿部血管传导率降低）两方面的限制。
