Evaluation of maximal lactate steady state in middle-aged hypertensive women

Abstract AIM The aim of this study was to investigate the lactate response in physically inactive hypertensive women submitted to the treadmill maximal lactate steady state (MLSS) protocol. METHODS Twenty-two hypertensive women (40 - 64 years) performed a familiarization period of walking on the treadmill following by one incremental test for estimating the initial workload for exercise testing. MLSS protocol was composed by walking in a treadmill during thirty minutes with fixed velocity in 5.5 km/h. Incline was used for determination of the intensity of each volunteer. Blood samples were collected from the ear lobe in the rest period, minute 10th and at the end of the test (minute 30th or at exhaustion time point) for lactate analysis. RESULTS Hypertensive women showed a lower lactate concentration at MLSS (3.25 ± 0.81 mmol/L) as compared with data obtained in the literature (4 mmol/L), approximately 18.8%. Neither inclines nor age affected MLSS parameters in the population. A positive and strong correlation was found between incline and MLSS, as well as incline and lactate level at minute 30th, even when adjusted by age factor. CONCLUSION Physically inactive hypertensive women show a lower MLSS than the average established in the literature but within the range of variations previously reported. Furthermore, a higher MLSS incline correlates positive and directly with higher lactate concentrations for the same aerobic capacity regardless of age.

研究目的
本研究旨在探讨久坐不动的高血压女性完成跑步机最大乳酸稳态（maximal lactate steady state, MLSS）方案时的乳酸应答反应。

方法
本研究纳入22名年龄介于40至64岁的高血压女性受试者，先进行跑步机步行适应训练，随后实施递增负荷试验以估算运动测试的初始工作负荷。MLSS方案采用跑步机步行模式，固定速度设定为5.5 km/h，持续时长30分钟，通过调整坡度确定每名受试者的运动强度。分别于静息期、试验第10分钟及试验结束时（第30分钟或力竭时刻）采集耳缘血样，用于乳酸水平分析。

结果
相较于文献报道的4 mmol/L参考值，本研究中高血压女性的MLSS时乳酸浓度更低，为3.25±0.81 mmol/L，降幅约18.8%。坡度与年龄均未对本研究人群的MLSS参数产生影响。研究发现坡度与MLSS、以及坡度与试验第30分钟时的乳酸水平均呈强正相关，即使在校正年龄因素后该关联依然成立。

结论
久坐不动的高血压女性的MLSS水平低于文献确立的平均参考值，但仍处于既往报道的变异范围之内。此外，在相同有氧能力条件下，更高的MLSS坡度与更高的乳酸浓度呈显著正相关，且该关联不受年龄影响。