The analysis of venous blood flow velocity increase during ankle exercise / 体力科学

Ankle exercises are useful for preventing deep vein thrombosis, as they increase venous blood flow velocity. The cause for the increased venous blood flow velocity during ankle exercises may be the skeletal-muscle pump, but the mechanism is not clearly understood. The purpose of this study was to investigate the effects of the dorsiflexion angle and gastrocnemius muscle contraction on venous blood flow velocity during ankle exercises and to investigate the mechanism of the increase in venous blood flow velocity. The blood flow velocity in the popliteal vein, ankle joint angle, and surface electromyographic activity of the gastrocnemius muscle were measured at rest and during ankle exercises in the prone position in young healthy volunteers. The significant increase in venous blood flow velocity was observed during dorsiflexion phase, max dorsiflexion and during planter flexion phase. The peak venous blood flow velocity was different in each subject and classified into four types. The correlations of venous blood velocity to ankle joint angle and with the surface electromyographic activity of the gastrocnemius muscle were not statistically significant. These findings suggest that venous blood flow velocity increases not only during plantar flexion and dorsiflexion.

Avaliação do volume de fluxo venoso da bomba sural por ultra-sonografia Doppler durante cinesioterapia ativa e passiva: um estudo piloto / Evaluation of venous flow volume of the calf muscle pump by Doppler ultrasound during active and passive kinesiotherapy: a pilot study

CONTEXTO: O fisioterapeuta na unidade hospitalar atua sobre os efeitos da hipoatividade ou inatividade do paciente acamado. Na prática diária, a contração do músculo da panturrilha é difundida entre os profissionais de saúde no ambiente hospitalar, principalmente nos períodos de pré e pós-operatório, como forma de diminuir a estase venosa e os riscos de trombose venosa profunda nos membros inferiores. OBJETIVO: Avaliar o volume de fluxo venoso na bomba sural, através de ultra-sonografia doppler, durante cinesioterapia ativa e passiva (flexão plantar do tornozelo). MÉTODOS: A amostra foi constituída por 30 indivíduos escolhidos aleatoriamente e submetidos a ultra-sonografia doppler da veia poplítea direita, visando mensurar o volume de fluxo sanguíneo em quatro momentos: repouso, compressão manual da panturrilha, movimentação passiva e ativa do tornozelo em flexão plantar. Na análise dos resultados, utilizou-se o teste t, sendo utilizado um valor de p < 0,05 como índice de significância estatística. RESULTADOS: Na amostra constituída, 16 eram do sexo feminino e 14 do sexo masculino, apresentando as seguintes médias: idade (31,57 anos), altura (1,68 m), peso (68,25 kg) e índice de massa corporal (24,16). Na análise estatística, a flexão plantar do tornozelo realizada de forma passiva, quando comparada ao valor basal, é significante (p < 0,000056) em relação à ativação da bomba sural, embora não tanto quanto o exercício ativo (p < 0,0000016). Também mostrou significância a compressão manual do músculo tríceps sural em relação ao exercício passivo (p < 0,000000081). CONCLUSÃO: Neste estudo, a flexão plantar do tornozelo de forma ativa mostrou-se estatisticamente mais eficaz do que a passiva na ativação da bomba sural, aumentando o volume do fluxo de sangue na veia poplítea e diminuindo a estase venosa nos membros inferiores.

BACKGROUND: In-hospital physical therapists work on the effects of hypoactivity or inactivity of bedridden patients. In daily practice, contraction of the calf muscle is commonly performed by health professionals in hospitals, especially in pre- and post-operative periods as a form of reducing venous stasis and risk of deep venous thrombosis in the lower limbs. OBJECTIVE: To assess venous flow volume at the calf muscle pump using color Doppler ultrasound during active and passive kinesiotherapy (ankle plantar flexion). METHODS: The sample consisted of 30 individuals randomly selected and submitted to color Doppler ultrasound of the right popliteal vein, aiming to measure blood flow volume in four periods: rest, manual calf compression, active and passive ankle movement in plantar flexion. The t test was used for statistical analysis, and p < 0.05 was used as an index of statistical significance. RESULTS: The sample consisted of 16 females and 14 males. Means were as follows: age (31.57 years), height (1.68 m), weight (68.25 kg), and body mass index (24.16). Statistical analysis showed that passive ankle plantar flexion was significant when compared to baseline (p < 0.000056) as to calf pump muscle activation, although not as much as active exercise (p < 0.0000016). Manual compression of the triceps surae muscle in relation to passive exercise was also significant (p < 0.000000081). CONCLUSION: In this study, active ankle plantar flexion proved statistically more effective than passive exercise in calf muscle pump activation, increasing blood flow volume in the popliteal vein and minimizing venous stasis in the lower limbs.

Effects of ramp and ballistic contractions on post-exercise hyperemia in human triceps surae / 体力科学

This study was designed to compare post-exercise hyperemia between ramp and ballistic contractions in human triceps surae. Subject was asked to extend ankle joint in range of 20 degrees for 1 sec and with maximum effort against loads of 10, 20, 30 or 40% of maximum voluntary contraction (MVC) in ankle extensors. Amount of post-exercise hyperemia was calculated from changes in calf girth recorded by using two strands mercury-in-rubber gauge.<BR>1) Calf girth after contractions transiently decreased below precontraction level and increased gradually until its peak value, over precontraction level, in about 8 sec. Calf girth recovered to resting level for about 30 sec.<BR>2) After ramp contractions, amount of decrease of calf volume increased in order to loads of 10, 20, 30 and 40% MVC, but was not so after ballistic contractions. Amount of its increase, excess precontraction level, depended on loads in both conditions. These values were below 1.0m<I>l</I>/100 m<I>l</I> tissue.<BR>3) Amount of decrease of calf volume after ramp contraction was larger than that of ballistic contraction, but amount of its increase was inverse.<BR>4) There was significant coefficient between calf volume increase after contraction and maximum inflow rate (m<I>l</I>/min/100 m<I>l</I> tissue) calculated from the maximum gradient in rising phase of calf girth (r=0.5508, p<0.001) .<BR>From these results, it is suggested that“milking action”in muscle generate with ramp contraction, and that disturbance of pulsatile inflow to muscle and chemical and neuronal regulations to generate post-exercise hyperemia pronouncely act by ballistic contraction.

A study of muscle pump. Relationship between contraction force and blood volume and pumping action / 体力科学

The purpose of this study was to investigate the effects of contraction force and the pooled blood volume in the calf on the pumping action of calf muscle contraction. Calf blood volume was controlled by lower body negative pressure (LBNP) and isometric contraction of calf extensor muscle was performed using a handmade dynamometer in recumbent position. The relative volume changes (ΔV/V%) of calf were determined using rubber straingage, when isometric contractions (5, 10, 20, 40 and 60 kg) of the calf muscle were repeated under LBNP of 0, -20, -40, and -60 mmHg.<BR>During resting condition, Δ V/V was increased by 1.04% under -20 mmHg LBNP, 1.88% under -40 mmHg, and 2.54% under -60 mmHg. These increases of ΔV/V were due to the increased blood pooling in the calf. It was shown that the increased blood volume was almost expelled by several bouts of muscle contractions of proper force. The optimum force of contractions for expelling pooled blood was 20 kg under -20mmHg LBNP, and 40 kg under -40 and -60 mmHg LBNP. And it was apparent that the effectiveness of muscle pump was accumulated with repeating contractions, arriving to a plateau after several bouts.<BR>It was shown that the effect of muscle pump in the given contraction force was more effective under the condition with more amount of blood contained in the calf, but the muscle pumping action by light contraction forces couldn't overcome the effect of severe LBNP.

Effect of muscle pump on hemodynamics. (Part 3). Transient changes at the start and end of exercise during LBNP / 体力科学

In order to evaluate the effect of muscle pump on blood circulation at the start and end of exercise, cardiac responses to pedaling exercise at 75 watt in the supine position were investigated under lower body negative pressure (LBNP) of -60mmHg. Six healthy male college students volunteered for subjects. Cardiac output (Q), stroke volume (SV), thoracic impedance (ZO) and heart rate (HR) were determined by using ensemble-averaged impedance cardiogram and ECG.<BR>The results obtained were as follows.<BR>1) By the initiation of exercise under LBNP, SV and Q promptly and more markedly increased and ZO decreased than the control experiment which were done under normal pressure. These changes were suggested to be caused by mobilization of previously pooled blood in the legs by muscle pump. Effects of muscle pump arrived to a plateau within about 30 sec after the start of exercise. And these effects were immediately disappeard by the cessation of exercise.<BR>2) By the release of LBNP during resting condition, the same changes were observed in SV, Q and ZO as in the start of exercise under LBNP. However HR decreased in the case while it increased in the case of exercise in LBNP. This difference in HR might be the result of the chronotropic effects by the exercise.<BR>3) In the very early phase of exercise in the control exercise, SV decreased and ZO increased. These changes were probably caused by superiority of chronotropic action by the exercise to increase in venous return in this position.<BR>These results led us to a conclusion that the effect of muscle pump appeares immediately by the start of the exercise and it arrives at plateau within about 30 sec. This effect is immediately disappeared by the cessation of exercise.

A STUDY OF MUSCLE PUMP / 体力科学

The purpose of this study was to investigate the effects of contraction force and the pooled blood volume in the calf on the pumping action of calf muscle contraction. Calf blood volume was controlled by lower body negative pressure (LBNP) and isometric contraction of calf extensor muscle was performed using a handmade dynamometer in recumbent position. The relative volume changes (ΔV/V%) of calf were determined using rubber straingage, when isometric contractions (5, 10, 20, 40 and 60 kg) of the calf muscle were repeated under LBNP of 0, -20, -40, and -60 mmHg.<BR>During resting condition, Δ V/V was increased by 1.04% under -20 mmHg LBNP, 1.88% under -40 mmHg, and 2.54% under -60 mmHg. These increases of ΔV/V were due to the increased blood pooling in the calf. It was shown that the increased blood volume was almost expelled by several bouts of muscle contractions of proper force. The optimum force of contractions for expelling pooled blood was 20 kg under -20mmHg LBNP, and 40 kg under -40 and -60 mmHg LBNP. And it was apparent that the effectiveness of muscle pump was accumulated with repeating contractions, arriving to a plateau after several bouts.<BR>It was shown that the effect of muscle pump in the given contraction force was more effective under the condition with more amount of blood contained in the calf, but the muscle pumping action by light contraction forces couldn't overcome the effect of severe LBNP.

Effect of muscle pump on hemodynamics. Part 2 / 体力科学

The purpose of this investigation is to evaluate the effects of muscle pump by pedaling exercise on blood circulation and define its properties. Lower body pressurization device equipped with bicycle ergometer was used to provide negative pressure on the lower body of subjects in recumbent position. Seven healthy male collage students volunteered for subjects.<BR>Whole experiment for each subjects was divided into control stage (0 mmHg), -20, -40, and -60 mmHg LBNP (lower body negative pressure) stage. Preceeded by resting period, 25, 75, and 125 W exercise in experiment 1, 50 and 100 W exercise in experiment 2 were loaded using bicycle ergometer with revolution of 60 rpm during each stage. Following parameters were determined: HR, SV, Q, and blood pressure.<BR>The results obtained were as follows;<BR>(1) In resting condition, LBNP caused significant decrease in SV and Q in spite of marked compensatory increase in HR.<BR>(2) These effects of LBNP were cancelled in -20 mmHg or mostly cancelled in -40 and -60 mmHg by pedaling exercise of 50 W or more.<BR>(3) Effect of muscle pump by pedaling exercise is apparent in light exercise such as 25 or 50 W arriving to a plateau with more intensive load.<BR>(4) Muscle pump action by the same exercise condition is more effective under more severe LBNP.<BR>(5) Light exercise in LBNP caused decrease in HR, probably because of pressure reflex initiated by restoration of blood pressure.<BR>These results leed us to a conclusion that light pedaling exercise produces a powerful pumping action nearly enough to compensate the circulatory disturbance by strong LBNP.

Effect of muscle pump on hemodynamics / 体力科学

The purpose of this study is to evaluate the effects of muscle pump of pedaling exercise on blood circulation. Lower body pressurization device was used to provide negative pressure and positive pressure on the lower body of subjects in recumbent position. This device is also equipped with bicycle ergometer in it. Five healthy male college students volunteered for subjects.<BR>Whole experiment for each subject was divided into pre-control stage (0 mmHg), LBPP (lower body positive pressure) stage (+40mmHg), LBNP (lower body negative pressure) stage (-40 mmHg) and post-control stage (0 mrHg) . 50 (watt) exercise and 100 (watt) exercise preceded by resting period were loaded during each stage and following parameters were determined: ECG, phonocardiogram, carotic pulse wave, VO<SUB>2</SUB>, cardiac output, and blood pressure. Pre-ejection period index (PEPi), Left ventricular ejection time index (LVETi), PEP/LVET and stroke volume (SV) were calculated from the recorded data.<BR>Results suggested following conclusions:<BR>1) In rest condition, LBNP caused marked increase in HR, PEPi, and PEP/LVET and remarkable decrease in Q, SV, and LVETi. These findings indicate that LBNP affects venous return and exaggerates venous pooling in lower body.<BR>2) It was shown that muscle pump of pedaling exercise counteracts the effects of LBNP and the findings mentioned above were largely abolished by pedaling exercise of 100 (watt) .<BR>3) LBPP caused no apparent change in the studied parameters except blood pressure. Blood pressure increased by LBPP probably because of rising in total peripheral resistance.