Heart rate and blood pressure responses to isometric exercise in young and older men

The aim of this study was to examine the isometric endurance response and the heart rate and blood pressure responses to isometric exercise in two muscle groups in ten young (age 23–29 years) and seven older (age 54–59 years) physically active men with similar estimated forearm and thigh muscle masses. Isometric contractions were held until fatigue using the finger flexor muscles (handgrip) and with the quadriceps muscle (one-legged knee extension) at 20%, 40%, and 60% of the maximal voluntary contraction (MVC). Heart rate and arterial pressure were related to the the individual's contraction times. The isometric endurance response was longer with handgrip than with one-legged knee extension, but no significant difference was observed between the age groups. The isometric endurance response averaged 542 (SEM 57), 153 (SEM 14), and 59 (SEM 5) s for the handgrip, and 276 (SEM 35), 94 (SEM 10) and 48 (SEM 5) s for the knee extension at the three MVC levels, respectively. Heart rate and blood pressure became higher during one-legged knee extension than during handgrip, and with increasing level of contraction. The older subjects had a lower heart rate and a higher blood pressure response than their younger counterparts, and the differences were more apparent at a higher force level. The results would indicate that increasing age is associated with an altered heart rate and blood pressure response to isometric exercise although it does not affect isometric endurance.     

Isometric strength and endurance during the menstrual cycle

Seven healthy young women, 3 of whom had been taking oral contraceptives, were examined during the course of 2 menstrual cycles to assess their isometric strength, their endurance during a series of 5 fatiguing isometric contractions at a tension of 40% MVC, and their blood pressures and heart rates during those fatiguing contractions. Two sets of experiments were performed, one in which the subject's forearm temperature was allowed to vary as a function of T _A , and one with the muscle temperature stabilized by immersion of the forearm in water at 37 C. During exposure to ambient temperatures, isometric strength and both the heart rate and blood pressure responses at rest and at the end of a fatiguing, sustained isometric exercise, were not significantly different during any phase of the menstrual cycle in any subject. In contrast, the isometric endurance in the women not taking oral contraceptives varied sinusoidally in all 5 contractions with a peak endurance midway through the ovulatory phase and the lowest endurance mid-way through the luteal phase of the menstrual cycle. The isometric endurance of the women taking oral contraceptives did not vary during their menstrual cycle. After stabilization of the temperature of the muscles of the forearm in water at 37 C, the isometric endurance of the normal subjects showed a hyperbolic response with the maximal endurance at the beginning and end of their cycles, and the shortest endurance at mid-cycle. Here again, however, the isometric endurance of the women taking oral contraceptives did not vary after immersion of their forearms in the 37 C water.     

Effects of Endurance and Endurance Strength Training on Body Composition and Physical Capacity in Women with Abdominal Obesity

AimsTo compare the effects of endurance training with endurance strength training on the anthropometric, body composition, physical capacity, and circulatory parameters in obese women.Methods44 women with abdominal obesity were randomized into groups A and B, and asked to perform endurance (A) and endurance strength training (B) for 3 months, 3 times/week, for 60 min. Dual-energy X-ray absorptiometry and Graded Exercise Test were performed before and after training.ResultsSignificant decreases in body mass, BMI, total body fat, total body fat mass, and waist and hip circumference were observed after both types of intervention. Marked increases in total body lean and total body fat-free mass were documented in group B. In both groups, significant increases in peak oxygen uptake, time to exhaustion, maximal work rate, and work rate at ventilatory threshold were accompanied by noticeably decreased resting heart rate, resting systolic blood pressure, and resting and exercise diastolic blood pressure. No significant differences were noticed between groups for the investigated parameters.ConclusionOur findings demonstrate evidence for a favorable and comparable effect of 3-month endurance and endurance strength training on anthropometric parameters, body composition, physical capacity, and circulatory system function in women with abdominal obesity.Key Words: Obesity, Exercise, Body composition     

The effect of ageing in spinal cord injured humans on the blood pressure and heart rate responses during fatiguing isometric exercise

Groups of 50 healthy male controls and 50 subjects suffering from paraplegia (aged 20–65 years) were examined as to the inter-relationships between age, paraplegia and the strength, endurance, blood pressure and heart rate responses to fatiguing isometric exercise. Contractions were maintained in both groups under voluntary effort and through a contraction induced by electrical stimulation in the paraplegic group. All contractions were maintained to fatigue at a tension of 40% of the maximal muscle strength in either the handgrip or quadriceps muscles. Muscle strength of the handgrip was higher in the paraplegic subjects than in the controls, averaging 589 N and 463 N, respectively for the two groups. In contrast, quadriceps leg extension strength averaged 696 N in the controls and 190 N in the paraplegic groups; for both groups, ageing was associated with a reduction in muscle strength. While leg endurance was less in the paraplegic group than the control group, handgrip endurance was similar in the two groups, endurance increasing with ageing in both the controls and paraplegics. Both systolic and diastolic blood pressures increased at rest in paraplegic and control subjects with age. The magnitude of the pressor response to exercise also increased with age. This was true during both voluntary exercise and exercise induced through electrical stimulation in the paraplegic groups. The heart rate response (change in heart rate during exercise) to a fatiguing isometric handgrip contraction decreased by about 50% between the ages of 20 and 60 years in both the controls and paraplegics for isometric handgrip exercise. In contrast, heart rate changed little with age during contractions of the quadriceps muscle in paraplegics which were induced by electrical stimulation. Electronic Publication     

The relationship between voluntary electromyogram,endurance time and intensity of effort in isometric handgrip exercise

The relationship between relative force, electromyogram (EMG) and time to fatigue was examined in seven male and seven female subjects [mean (SD) age, 21.7 (3.2) years] during isometric handgrip exercise. Subjects performed sustained submaximal contractions of the right handgrip at three different intensities: 30%, 50%, and 75% of the pretrial maximum voluntary contraction (MVC). EMG was sampled in 1-s epochs every 15 s during the contractions, and the integrated EMG (IEMG) values were then normalized to that of the pretrial MVC. As expected, time to fatigue was longest at 30% MVC and shortest at 75% MVC, but women performed consistently longer than men at each of the three intensities [woman vs men; 400.7 (35.8) vs 364.3 (34.4) s, 205.1 (15.6) vs 139.4 (13) s, and 89.9 (11.4) vs 66.4 (6.4) s, for 30%, 50%, and 75% MVC, respectively; P < 0.05)]. IEMG increased in a non-linear fashion over time during each trial, with the magnitude of IEMG being proportional to the intensity of the contraction. At the endurance limit, IEMG was greatest in the 75% MVC trial, however, no IEMG values reached those obtained in the related MVC [30%, 57.2 (6.9)%; 50%, 84.6 (5.7)%; 75%, 92.8 (7.4)%]. In conclusion, endurance time during sustained submaximal isometric handgrip exercise is dependent up on the intensity of the effort, with women having significantly larger endurance times than men. The related increase in IEMG is also proportional to the intensity of effort, however, the factors causing force to fail prior to the final IEMG reaching its predicted maximum remain to be elucidated.     

Blood pressure and heart rate responses during a fatiguing isometric exercise in paraplegic men with hypertension

A group of 45 male subjects were examined in a cross-sectional study to compare the blood pressure response that occurs during isometric exercise maintained to fatigue among control subjects and paraplegic patients with (PH) and without essential hypertension (PN). Two muscle groups were examined: the handgrip muscles (voluntary effort) and the quadriceps muscles. The tension chosen for the contraction was 40% of the muscles maximum strength for both muscle groups. While the paraplegic groups had more strength in their handgrip muscles than that found for the controls, the control subjects had more strength in their quadriceps muscles than either of the paraplegic groups. During the fatiguing isometric contractions, the rate of rise and absolute systolic blood pressure was higher in the PH than the other groups of subjects. The diastolic pressure of the PH group, while elevated during exercise, was only elevated to the same degree as the increase in resting diastolic pressure above normal. Heart rate changes during exercise was the same in all groups of subjects for handgrip contractions. The controls had the same heart rate response to handgrip as to leg exercise. The paraplegic groups showed no heart rate change during fatiguing contractions of their quadriceps muscles. The PH group actually showed a reduction in heart rate during the leg exercise. Accepted: 10 July 2000     

A comparison of physiological variables in aged and young women during and following submaximal exercise

Previously, we have examined how aging affects the physiological responses of men to endurance exercise. In the present investigation, we aimed to extend our assessment of the influence of aging on exercise‐induced responses by focusing on women. Ten young (20.3 ± 0.3 years; mean ± SE) and 10 aged (75.5 ± 1.2 years) women performed 30 min of cycling at 60–65% of their predetermined peak oxygen uptake. Data for respiratory exchange ratio (RER), heart rate, blood pressure, rectal temperature, and plasma metabolites were collected before exercise, at the 15th and 30th min of exercise, and at 5 and 15 min postexercise. A two‐way, repeated measures ANOVA with main effects of age and time was conducted on each variable. Our findings showed that age affected exercise‐induced responses of each variable quantified. Although RER, heart rate, temperature, and lactate were significantly (P < 0.05) higher among young women, blood pressure and glucose values were greater among aged women. Moreover, unlike previous results noted among men where age‐related differences primarily occurred during postexercise recovery, in women the effect of aging was detected during exercise itself. The data presented here indicate that aging impacts physiological responses of women to prolonged endurance exercise even when relative intensity (% of peak oxygen uptake) is held constant. Combined with our earlier study on men, these findings suggest that gender interacts with aging to determine whether age‐related differences are manifested during exercise itself, or during postexercise recovery. Am. J. Hum. Biol., 2009. © 2009 Wiley‐Liss, Inc.     

Recovery of the human biceps electromyogram after heavy eccentric,concentric or isometric exercise

Summary Five men performed submaximal isometric, concentric or eccentric contractions until exhaustion with the left arm elbow flexors at respectively 50%, 40% and 40% of the prefatigued maximal voluntary contraction force (MVC). Subsequently, and at regular intervals, the surface electromyogram (EMG) during 30-s isometric test contractions at 40% of the prefatigued MVC and the muscle performance parameters (MVC and the endurance time of an isometric endurance test at 40% prefatigued MVC) were recorded. Large differences in the surface EMG response were found after isometric or concentric exercise on the one hand and eccentric exercise on the other. Eccentric exercise evoked in two of the three EMG parameters [the EMG amplitude (root mean square) and the rate of shift of the EMG mean power frequency (MPF)] the greatest (P<0.001) and longest lasting (up to 7 days) response. The EMG response after isometric or concentric exercise was smaller and of shorter duration (1–2 days). The third EMG parameter, the initial MPF, had already returned to its prefatigued value at the time of the first measurement, 0.75 h after exercise. The responses of EMG amplitude and of rate of MPF shift were similar to the responses observed in the muscle performance parameters (MVC and the endurance time). Complaints of muscle soreness were most frequent and severe after the eccentric contractions. Thus, eccentric exercise evoked the greatest and longest lasting response both in the surface EMG signal and in the muscle performance parameters.     

Blood pressure and heart rate responses during a fatiguing isometric exercise in paraplegic men with hypertension

A group of 45 male subjects were examined in a cross-sectional study to compare the blood pressure response that occurs during isometric exercise maintained to fatigue among control subjects and paraplegic patients with (PH) and without essential hypertension (PN). Two muscle groups were examined: the handgrip muscles (voluntary effort) and the quadriceps muscles. The tension chosen for the contraction was 40% of the muscles maximum strength for both muscle groups. While the paraplegic groups had more strength in their handgrip muscles than that found for the controls, the control subjects had more strength in their quadriceps muscles than either of the paraplegic groups. During the fatiguing isometric contractions, the rate of rise and absolute systolic blood pressure was higher in the PH than the other groups of subjects. The diastolic pressure of the PH group, while elevated during exercise, was only elevated to the same degree as the increase in resting diastolic pressure above normal. Heart rate changes during exercise was the same in all groups of subjects for handgrip contractions. The controls had the same heart rate response to handgrip as to leg exercise. The paraplegic groups showed no heart rate change during fatiguing contractions of their quadriceps muscles. The PH group actually showed a reduction in heart rate during the leg exercise.     

The combined effect of the cold pressor test and isometric exercise on heart rate and blood pressure

Summary The purpose of this study was to determine if the cold pressor test during isometric knee extension [15% of maximal voluntary contraction (MVC)] could have an additive effect on cardiovascular responses. Systolic and diastolic blood pressures, heart rate and pressure rate product were measured in eight healthy male subjects. The subjects performed the cold pressor tests and isometric leg extensions singly and in combination. The increases of systolic and diastolic blood pressure during isometric exercise were of almost the same magnitude as those during the cold pressor test. The responses of arterial blood pressure, and heart rate to a combination of the cold pressor test and isometric knee extension were greater than for each test separately. It is suggested that this additional effect of cold immersion of one hand during isometric exercise may have been due to vasoconstriction effects in the contralateral unstressed limb. In summary, the circulatory effects of the local application of cold during static exercise at 15% MVC were additive.     

The effects of isometric exercise training on resting blood pressure and orthostatic tolerance in humans

Isometric exercise training has been shown to reduce resting blood pressure, but the effect that this might have on orthostatic tolerance is poorly understood. Changes in orthostatic tolerance may also be dependent on whether the upper or lower limbs of the body are trained using isometric exercise. Twenty-seven subjects were allocated to either a training or control group. A training group first undertook 5 weeks of isometric exercise training of the legs, and after an 8 week intervening period, a second training group containing six subjects from the initial training group, undertook 5 weeks of isometric arm-training. The control group were asked to continue their normal daily activities throughout the 18 weeks of the study. In all subjects orthostatic tolerance, assessed using lower body negative pressure (LBNP), and resting blood pressure were measured before and after each of the 5 week training or control periods. Estimated lean leg volume was determined before and after leg-training. During all LBNP tests, heart rate and blood pressure were recorded each minute, and the time taken to reach the highest heart rate was derived (time to peak HR). Resting systolic blood pressure (mean +/- S.D.), when measured during the last week of training, was significantly reduced after both leg (-10 +/- 8.7 mmHg) and arm (-12.4 +/- 9.3 mmHg; P < 0.05) isometric exercise training, compared to controls. This reduction disappeared when blood pressure was measured immediately before the LBNP tests, which followed training. Orthostatic tolerance only increased after leg-training (20.8 +/- 16.4 LTI; P < 0.05) and was accompanied by an increased time to peak HR (119.8 +/- 106.3 beats min(-1); P < 0.05) in this group. Blood pressure responses to LBNP did not change after arm-training, leg-training or in controls (P > 0.05). There was a small but significant increase in estimated lean leg volume after leg-training (0.1 +/- 0.1 1; P < 0.05). These results suggest that lower resting blood pressure is probably not responsible for the increased orthostatic tolerance after isometric exercise training of the legs. Rather, it is possible that the training altered some other aspect of cardiovascular control during orthostatic stress that was apparent in the changes in heart rate. Leg-training was accompanied by increases in estimated lean leg volume. The effects of isometric training on orthostatic tolerance appear to be specific to limbs that are directly involved in LBNP testing.     

Circulatory effects of isometric muscle contractions,performed separately and in combination with dynamic exercise

Studies on central circulation and regional blood flow were performed in healthy male volunteers at rest, during sustained isometric forearm contraction at 20% of MVC, during dynamic leg exercise (100 W) and during combined isometric and dynamic exercise. In 10 subjects pulmonary oxygen uptake, arterio-venous oxygen difference, heart rate, leg blood flow and blood pressures in the pulmonary and subclavian arteries and in the right atrium were measured. In 4 of these subjects the temperature was measured in mixed venous blood and in subcutaneous tissue in an attempt to further analyse the blood flow distribution through central versus peripheral parts of the circulatory system. In 5 other subjects the splanchnic blood flow was estimated by hepatic vein catheterization and dye dilution technique at rest and during isometric forearm contraction. It was found that cardiac output, oxygen uptake, heart rate and arterial blood pressure all increased in response to isometric contraction. Quantitatively the changes in heart rate and cardiac output induced by a sustained contraction were more marked when the contraction was performed separately than when it was added to dynamic exercise. In spite of the increased arterial pressure, the leg blood flow did not increase significantly. Neither did the splanchnic blood flow increase in response to hand-grip contraction. The blood temperature in the pulmonary artery rose during isolated dynamic exercise. Isometric exercise, however, caused a blood temperature fall and a rise in subcutaneous temperature indicating an increased blood flow through the skin. It is concluded that during sustained isometric muscle contraction

1. the blood flow increase is mainly distributed to peripheral circulatory areas,
2. a concomitant dynamic exercise interferes with the circulatory adaptation only to a small extent.

     

Physiological modifications of local haemodynamic conditions during bilateral isometric contractions

Summary Nine subjects (five women and four men) simultaneously performed two isometric contractions sustained until exhaustion at different relative forces: 40% of maximum voluntary contraction (MVC) for the right elbow flexors; 50% MVC for the left elbow flexors. Contraction of the left elbow flexors commenced at 50% of the limit time (maximum maintenance time) of isometric contraction of the right elbow flexors. Increase in heart rate during concomitant contraction of the left elbow flexors led to an increase in blood flow to the right elbow flexors. Under these conditions, the limit time of isometric contraction of the right elbow flexors was prolonged with respect to the limit time obtained for an isolated isometric contraction at the same relative tension. The difference was more significant in the female (+40%,P<0.05) than in the male subjects (+20%,P>0.05).     

Endurance capacity of untrained males and females in isometric and dynamic muscular contractions

Summary The capacity to perform isometric and dynamic muscle contractions at different forces has been measured in two separate groups of subjects: 25 men and 25 women performed sustained isometric contractions of the knee-extensor muscles of their stronger leg to fatigue, at forces corresponding to 80%, 50% and 20% of the maximum voluntary force of contraction (MVC). The second experimental model involved a bilateral elbowflexion weight lifting exercise. Eleven women and 12 men performed repetitions at loads corresponding to 90%, 80%, 70%, 60% and 50% of maximum load (lRM), at a rate of 10 · min^–1 to the point of fatigue. Males were stronger (p<0.001) than females in both the static (675±120 N vs 458±80 N; mean±SD) and dynamic (409±90 N vs 190±33 N) contractions. Isometric endurance time of the males at a force corresponding to 20% of MVC was less than that of the females (180±51 s vs 252±56 s; p<0.001) but there was no difference between the sexes at 50% or 80% of MVC. Similarly, when the sexes were compared using dynamic elbow-flexion exercise, the female subjects were able to perform a greater number of repetitions than males at loads of 50% (p<0.005), 60% (p<0.001) and 70% (p<0.025) of lRM, but there was no difference between the sexes at loads of 80% or 90% of lRM. The results suggest that the endurance capacity of women is greater than that of men in both isometric and dynamic muscular exercise when the work load is relatively low compared with maximum; at higher forces, there is no difference between the sexes in endurance performance.     

Measurement of forearm blood flow by venous occlusion plethysmography: Influence of hand blood flow during sustained and intermittent isometric exercise

Summary The requirement for using an arterial occlusion cuff at the wrist when measuring forearm blood flows by plethysmography was tested on a total of 8 subjects at rest and during and after sustained and intermittent isometric exercise. The contribution of the venous effluent from the hand to the forearm flow during exercise was challenged by immersing the arm in water at 20, 34, and 40 C. Occlusion of the circulation to the hand reduced the blood flow through the resting forearm at all water temperatures. There was an inverse relationship between the temperature of the water and the proportion in the reduction of forearm blood flow upon inflation of the wrist-cuff, ranging from 45 to 19% at 20 to 40 C, respectively. However, during sustained isometric exercise at 10% of the subjects maximum voluntary contraction (MVC) there was no reduction in the measured forearm flow when an arterial occlusion cuff was inflated around the wrist. Similarly, there was no alteration in the blood flow measured 2 s after each of a series of intermittent isometric contractions exerted at 20% or 60% MVC for 2 s whether or not circulation to the hand was occluded nor of the post-exercise hyperemia following 1 min of sustained contraction at 40% MVC. These results indicate that a wrist-cuff is not required for accurate measurement of forearm blood flows during or after isometric exercise.This work was supported by N.I.H. training grant HLO 7050-03, H.E.W. contract 210-77-0044 and Air Force grant AFOSR-76-3084 B     

The influence of straining maneuvers on the pressor response during isometric exercise

Summary Experiments were performed to determine to what extent increments in esophageal and abdominal pressure would have on arterial blood pressure during fatiguing isometric exercise. Arterial blood pressure was measured during handgrip and leg isometric exercise performed with both a free and occluded circulation to active muscles. Handgrip contractions were exerted at 33 and 70% MVC (maximum voluntary contraction) by 4 volunteers in a sitting position and calf muscle contractions at 50 and 70% MVC with the subjects in a kneeling position. Esophageal pressure measured at the peak of inspirations did not change during either handgrip or leg contractions but peak expiratory pressures increased progressively during both handgrip and leg contractions as fatigue occurred. These increments were independent of the tensions of the isometric contractions exerted. Intra-abdominal pressures measured at the peak of either inspiration or expiration did not change during inspiration with handgrip contractions but increased during expiration. During leg exercise, intraabdominal pressures increased during both inspiration and expiration, reaching peak levels at fatigue. The arterial blood pressure also reached peak levels at fatigue, independent of circulatory occlusion and tension exerted, averaging 18.5–20 kPa (140–150 mm Hg) for both handgrip and leg contrations. While blood pressure returned to resting levels following exercise with a free circulation, it declined by only 2.7–3.8 kPa after leg and handgrip exercise, respectively, during circulatory occlusion. These results indicate that straining maneuvers contribute 3.5 to 7.8 kPa to the change in blood pressure depending on body position.     

Muscle strength and body composition as determinants of blood pressure in young men

Summary The correlations of blood pressure to various indices of muscularity and fatness were studied in 183 young healthy men (mean age 19.7, SD 2.1 years). Systolic pressure showed significant positive correlations with body fat percentage, isometric strength of trunk extensors, body mass index, lean body mass, strength of leg extensors, heart rate, and the sum of four skinfolds. Diastolic pressure had significant positive correlations with body mass index, lean body mass, body fat percentage, sum of skinfolds, strength of leg extensors, strength of trunk extensors, and age. A stepwise selective multiple regression analysis for systolic pressure resulted in four significantly correlating variables: body fat percentage (p<0.001), heart rate (p<0.01), lean body mass (p< 0.05), and strength of trunk extensors per kg body weight (p<0.05). For diastolic pressure the analysis resulted in two explaining variables: body mass index (p<0.001) and age (p<0.05). In a regression equation with 13 variables the strength of trunk flexors was negatively correlated with diastolic pressure.It is concluded that both fatness and muscularity are factors related to blood pressure in young men. The muscularity effect is more clearly associated with trunk and leg extensor strength.     

Fluctuations of isometric force after eccentric exercise of the elbow flexors of young,middle-aged,and old men

This study compared force fluctuations during isometric contraction following eccentric exercise of the elbow flexors between young, middle-aged, and old subjects. Ten young (20 ± 2.0 years), 12 middle-aged (48 ± 7.3 years), and 10 old (71 ± 4.1 years) men performed six sets of five eccentric actions of the elbow flexors using a dumbbell weighing 40% of maximal voluntary isometric contraction strength (MVC) at an elbow joint angle of 90° (1.57 rad). MVC was measured before, immediately after, and 1–5 days following exercise, and the force fluctuations were assessed at 30, 50, and 80% of the corresponding time point MVC using coefficient of variation (CV) of force data collected at a frequency of 100 Hz for 4 s. Changes in MVC and CV over time were compared between groups by a two-way repeated measures ANOVA. Changes in MVC following exercise were not significantly different between the young and middle-aged groups, but the old group showed significantly (P < 0.05) smaller decreases in MVC compared with other groups. CV increased significantly (P < 0.05) only immediately after exercise without a significant difference among the three intensities, and no significant differences between groups were evident. It was concluded that force fluctuations during submaximal isometric tasks after eccentric exercise were not affected by age.     

Effect of graded changes in extracellular muscle volume on cardiovascular drives during static exercise

Summary The effects of graded changes in peripheral extracellular volume on heart rate and blood pressure during isometric exercise were studied in 12 healthy male subjects. Each subject performed four calf ergometer tests with each calf. In all tests, static plantar flexion of one foot was performed in a supine body position with the knee joint flexed to 90°. After a pre-exercise period of 18 min, during which the calf volume was manipulated, the subjects had to counteract a spring force of 120 N for 8 min. In the pre-exercise period the peripheral extracellular volume of the calf muscle to be tested was manipulated in four ways. Test 1: 15 min of rest in the exercise position. During the last 3.5 min, the calf volume was increased by venous congestion [80 mmHg (10.67 kPa) applied to the distal part of the thigh by pneumatic cuff]. Test 2: the same protocol as in test 1 but with 7.5-min venous congestion. Test 3: 15 min of venous congestion. Test 4: the calf volume was decreased by a negative hydrostatic pressure for 15 min (calf raised about 40 cm above heart level). To clamp the changed calf volume, the thigh cuff was rapidely inflated to 300 mmHg (40.0 kPa) at the end of the volume manipulation and the subjects remained resting for a further 3 min. In test 4, the leg of the subject was passively brought into the exercise position. The occlusion was maintained until 2 min after exercise. The calf volume manipulation led to changes ranging from +105 ml (test 3) to –134 ml (test 4) as measured by water displacement plethysmography. The blood pressure response to exercise was inversely related to the calf volume changes while the heart rate response during exercise showed no clearcut relationship to the pretreatments.     

Shoulder muscle strength and fatigability in patients with frozen shoulder syndrome: the effect of 4-week individualized rehabilitation

The effect of 4-week individualized rehabilitation on shoulder muscle strength and fatigability was evaluated in 10 patients with frozen shoulder syndrome (FSS) in comparison of 10 age- and gender-matched healthy control subjects. Isometric maximal voluntary contraction (MVC) force of the shoulder flexors was measured by hand-held dynamometer. Isometric endurance of the shoulder muscles was characterized by endurance time and net impulse (NI) assessed during weight (30% MVC) holding in hand until exhaustion. Fatigability of deltoideus, infraspinatus and trapezius muscles during isometric endurance test was assessed by electromyogram (EMG) power spectrum median frequency (MF) slope per minute. Rehabilitation in patients with FSS consisted of exercise therapy in swimming pool and gymnasium, electrical therapy and massage. Before rehabilitation, patients with FSS had less (p < 0.05) isometric MVC force and NI during endurance test compared to the control. MF slope in patients with FSS for involved extremity was higher (p <0.05) for the deltoideus muscle and less for the infraspinatus muscle before rehabilitation compared to the controls. Shoulder pain was decreased (p < 0.05) and isometric MVC force and NI in endurance test in patients for involved extremity were increased after rehabilitation. No significant changes in endurance time and MF slope for infraspinatus and trapezius muscles in patients for involved extremity were observed after rehabilitation, whereas MF slope for deltoideus muscle was increased. It was concluded that in patients with FSS, 4-week rehabilitation decreased shoulder pain and improved MVC force of the shoulder flexors and isometric working capacity of these muscles during endurance test.