Fallentin N, Sidenius B, Jørgensen K
Acta Physiol Scand. 1985 Oct;125(2):265-75. doi: 10.1111/j.1748-1716.1985.tb07715.x.
The purposes of the present investigation were: to evaluate a possible use of changes in the mean spectral frequency (MSF) of the EMG power spectra as a measure of reflex cardiovascular responses originating from the muscles during static exercise; and to study the relation between muscle fibre composition, EMG, and the cardiovascular response. Heart rate (HR), arterial blood pressure (BP), myoelectric signal (EMG), and intramuscular temperature (Tm) were measured during prolonged static contractions in five healthy male subjects (25-44 yrs). Two studies were performed. In study I constant EMG contraction muscle force in the first 5 s of the knee-extensor contraction was set to 20% MVC, (maximal voluntary contraction), and in the rest of the 5 min contraction the myoelectric signal was kept constant by visual feedback from an oscilloscope. In study II, (constant force contraction) two 1 h 7% MVC isometric contractions of the elbow-flexors and extensors were performed on two separate days. During the 5 min constant EMG contraction, the force fell from 20 to 11% MVC, mean BP (MAP) increased from 97 +/- 5 to 120 +/- 4 mmHg (P less than 0.01), and the EMG MSF decreased from 87 +/- 16 to 66 +/- 9 Hz (P less than 0.01). The decrease in MSF was strongly correlated to the increase in MAP (r = 0.96, P less than 0.01). The intramuscular temperature showed a small increase from 34.3 degrees C to 35.3 degrees C (P less than 0.01). During the 1 h constant force contraction involving m. triceps, MAP increased from 104 +/- 10 to 120 +/- 12 mmHg, with a simultaneous decrease in the EMG MSF from 96 +/- 11 to 70 +/- 19 Hz and an increase in the EMG amplitude (247% of the initial value). In the contractions involving m. biceps, however, both MAP and EMG MSF remained almost unchanged, but EMG amplitude increased (197% of the initial value). Very modest changes in HR were observed: 63 +/- 6 to 66 +/- 6 beats min-1 and 61 +/- 5 to 59 +/- 7 beats min-1 in the contractions involving m. triceps and m. biceps, respectively. The intramuscular temperature increased simultaneously, 1.3 degrees C and 0.7 degrees C in m. triceps and m. biceps, respectively. The results from the constant EMG contractions indicate the existence of a common 'trigger' for both the increase in BP and the decrease in EMG MSF; and the extracellular [K] is put forward as a candidate.(ABSTRACT TRUNCATED AT 400 WORDS)
评估肌电图功率谱平均频谱频率（MSF）的变化作为静态运动期间源自肌肉的反射性心血管反应指标的可能用途；并研究肌肉纤维组成、肌电图与心血管反应之间的关系。在5名健康男性受试者（25 - 44岁）进行长时间静态收缩期间，测量了心率（HR）、动脉血压（BP）、肌电信号（EMG）和肌肉内温度（Tm）。进行了两项研究。在研究I中，膝伸肌收缩前5秒的肌电图恒定收缩肌肉力量设定为20%最大自主收缩（MVC），在其余5分钟收缩期间，通过示波器的视觉反馈使肌电信号保持恒定。在研究II（恒定力量收缩）中，在两个不同的日子对肘屈肌和伸肌进行了两次1小时7%MVC的等长收缩。在5分钟的肌电图恒定收缩期间，力量从20%MVC降至11%MVC，平均血压（MAP）从97±5 mmHg升至120±4 mmHg（P<0.01），肌电图MSF从87±16 Hz降至66±9 Hz（P<0.01）。MSF的降低与MAP的升高密切相关（r = 0.96，P<0.01）。肌肉内温度从34.3℃略有升高至35.3℃（P<0.01）。在涉及肱三头肌的1小时恒定力量收缩期间，MAP从104±10 mmHg升至120±12 mmHg，同时肌电图MSF从96±11 Hz降至70±19 Hz，肌电图幅度增加（初始值的247%）。然而，在涉及肱二头肌的收缩中，MAP和肌电图MSF几乎保持不变，但肌电图幅度增加（初始值的197%）。观察到心率变化非常小：在涉及肱三头肌和肱二头肌的收缩中，分别从63±6次/分钟变为66±6次/分钟和从61±5次/分钟变为59±7次/分钟。肌肉内温度同时升高，肱三头肌和肱二头肌分别升高1.3℃和0.7℃。肌电图恒定收缩的结果表明，血压升高和肌电图MSF降低存在共同的“触发因素”；细胞外[K]被提出作为候选因素。（摘要截断于400字）
