Development of the automated double product break-point determining system

已知儿茶酚胺浓度在工作速率高于血乳酸阈值（LT）时急剧增加，因此我们假设双产物（DP，心率收缩压产物）也可能在工作速率高于LT时突然增加。本研究旨在设计自动DPBP测量系统，并阐明是否可以在跑步机和循环计力器上使用该系统进行斜坡测试来确定DPBP。我们设计了一套能在运动过程中自动测量收缩压和心率的系统，并在个人电脑（NEC PC98）上显示。通过这种修改，我们几乎可以每15秒自动测量一次DP。DPBP使用以下计算机算法自动确定。将所有可能的数据划分为两个调整组，计算DP作为W的函数的线性回归线，然后由代表平方和残差最小的两条线的交点确定断点。这种改进的仪器可用于测定所有受试者的DPBP，包括老年人和心脏病患者，在跑步机上进行斜坡试验和循环测力仪。测定DPBP的重测信度及DPBP与LT、VT的相关性均较好。基于以上研究结果，我们得出结论，该系统确定的DPBP是一个简单有效的评估身体素质和处方的最佳强度。

Catecholamine concentrations are known to sharply increase in the blood at work rates above the blood lactate threshold (LT), and thus we hypothesized that the double product (DP,heart rate-systolic blood pressure product) may also abruptly increase at work rates above the LT.This research was aimed at devising automatic DPBP measurement system and to clarify whether the DPBP could determined during a ramp test on treadmill and cycle ergometer using thsi system. We devised the system which could measure SBP and HR automaticaly and displayd those on the monitor during exercise using a personal computer (NEC PC98). By this modification, we could automatically measure the DP almost every 15 sec. The DPBP was automatically determined using a computer algorithm as follows. The liner regression lines of DP as a function of W were calculated for all possible divisions of the data into two adjustment groups, and then the break-point was determined by the intersection of the two lines which represented the minimum residual sum of the squares. This modified apparatus could be used to determine DPBP in all suqomects including elderly and cardiac patient with a ramp test on treadmill as well as cycle ergometer. The test-retest reliability to determine the DPBP and correlation among the determined DPBP,LT,and VT was fairly good. Based on the above findings we therefore concluded that DPBP determined by this system is easy and a valid for evaluating a physical fitness and prescribing a optimal intensity.