McKeever K H, Malinowski K
Department of Animal Science, Cook College, Rutgers-The State University of New Jersey, New Brunswick 08903-0231, USA.
Am J Vet Res. 1997 Dec;58(12):1468-72.
To test the hypothesis that, compared with unfit young horses, unfit older horses have lower aerobic capacity and reduction in other indices of exercise capacity.
6 young (mean +/- SEM, 5.3 +/- 0.8 years and 445 +/- 13 kg) and 6 aged (22.0 +/- 0.4 years and 473 +/- 18 kg) healthy Standardbred and Thoroughbred mares.
The mares, accustomed to running on a treadmill, were tested by use of an incremental exercise test. None of the mares had received exercise training for at least 4 months prior to the study. During testing, mares ran up a fixed 6% grade, starting at a speed of 4 m/s, with 1 m/s increase every 60 seconds (omitting 5 m/s) until they reached fatigue. Maximal oxygen uptake (VO2max) was measured by use of an open-flow calorimeter. Venous blood samples (10 ml) were collected during the last 10 seconds of each step and were used to measure blood lactate concentration and PCV. Calculated performance indices included velocity at VO2max, maximal velocity, and velocity at lactate concentration of 4 mmol/L; work rate (watts) at those velocities also was determined.
There were differences (P < 0.05) between old and young mares for maximal run velocity attained during the test (8.7 +/- 0.5 versus 10.8 +/- 0.5 m/s, respectively), VO2max (89.4 +/- 4.3 versus 117.3 +/- 9.5 ml/kg of body weight/min, respectively), and velocity at VO2max (8.0 +/- 0.4 versus 9.8 +/- 0.7 m/s, respectively). Also, velocity required to reach blood lactate concentration of 4 mmol/L was lower (P < 0.05) in old (7.5 +/- 0.4 m/s), compared with young (10.2 +/- 0.7 m/s), mares.
Older mares have substantially (-24%) lower maximal aerobic capacity than do young mares.
Many horses participate in athletic activities into their late teens and some do so beyond the age of 20 years; thus, the need exists to explore ways to adjust training programs for older horses.
验证与不健壮的年轻马匹相比,不健壮的老龄马匹有氧能力较低且运动能力的其他指标有所下降这一假设。
6匹年轻(平均±标准误,5.3±0.8岁,体重445±13千克)和6匹老龄(22.0±0.4岁,体重473±18千克)健康的标准赛马和纯种母马。
让习惯在跑步机上跑步的母马进行递增运动试验。在研究前,所有母马至少4个月未接受运动训练。测试期间,母马以固定的6%坡度奔跑,起始速度为4米/秒,每60秒增加1米/秒(跳过5米/秒),直至疲劳。使用开放式量热计测量最大摄氧量(VO2max)。在每个阶段的最后10秒采集静脉血样本(10毫升),用于测量血乳酸浓度和红细胞压积。计算得出的性能指标包括VO2max时的速度、最大速度以及血乳酸浓度为4毫摩尔/升时的速度;还测定了这些速度下的工作率(瓦特)。
老龄和年轻母马在测试中达到的最大奔跑速度(分别为8.7±0.5和10.8±0.5米/秒)、VO2max(分别为89.4±4.3和117.3±9.5毫升/千克体重/分钟)以及VO2max时的速度(分别为8.0±0.4和9.8±0.7米/秒)方面存在差异(P<0.05)。此外,老龄母马(7.5±0.4米/秒)达到血乳酸浓度4毫摩尔/升所需的速度低于年轻母马(10.2±0.7米/秒)(P<0.05)。
老龄母马的最大有氧能力比年轻母马低约24%。
许多马匹在接近20岁时仍参与体育活动,有些甚至超过20岁;因此,有必要探索调整老龄马匹训练计划的方法。