Neuromuscular and hormonal responses to a single session of whole body vibration exercise in healthy young men

Whole body vibration (WBV) has been proposed as an alternative exercise stimulus to produce adaptive responses similar to resistance exercise. Few studies have analysed acute hormonal responses to WBV. Purpose To evaluate neuromuscular and hormonal responses to an acute bout of isometric half-squat exercise with and without superimposition of WBV. Methods Seven healthy males (22.3+/-2.7 years) performed 10 sets of half squat isometric exercise for 1 min with 1-min rest between sets. Two separate trials were conducted either with WBV [30 Hz; 3.5 g (1 g=9.81 m.s2)] or without vibration (Control). Salivary concentration of testosterone and cortisol was collected and maximal isometric unilateral knee extensions (MVC) were completed before, immediately after, 1, 2 and 24 h after treatment. Results Significant decreases in MVC were observed immediately after (229.4+/-53.2 Nm), 1 h (231.6+/-59.9 Nm), and 2 h (233.0+/-59.1 Nm) after WBV compared with baseline (252.7+/-56.4 Nm; P<0.05). No significant change in MVC was recorded in Control. Rate of torque development in the first 200 ms (RTD200 ms), and salivary testosterone and cortisol concentrations were unaffected in both conditions. However, there was a trend for change over time in cortisol (P=0.052), with an increase after WBV and decrease after Control. Conclusion A 10 min session of intermittent WBV was shown to produce an acute reduction in MVC in healthy individuals, which recovered after 24 h. No significant changes were identified in salivary concentration of testosterone and cortisol suggesting that WBV with low acceleration does not represent a stressful stimulus for the neuroendocrine system.     

力竭性运动对官兵甲状旁腺素、睾酮、皮质醇和胃泌素水平的影响

目的探讨机体在力竭性运动前后血清激素水平的变化。方法采用放射免疫分析法分别对100例官兵在军事对抗演习前后进行血清激素水平测定。结果演习前血清皮质醇、睾酮含量分别为(216.35±53.54)ng/mL、(462.29±189.64)ng/dL,演习结束后含量分别为(166.95±68.40)ng/mL、(419.34±157.11)ng/dL,演习结束后皮质醇、睾酮水平明显低于演习前(P<0.05);演习前血清甲状旁腺素含量为(4.62±4.36)ng/L,演习结束后含量为(18.37±8.00)ng/L,演习结束后甲状旁腺素水平明显高于演习前(P<0.05);演习前血清胃泌素含量为(25.96±10.37)pg/mL,演习结束后含量为(25.97±10.78)pg/mL,演习前后胃泌素差异无统计学意义(P>0.05)。结论力竭性运动对血清皮质醇、睾酮和甲状旁腺素影响显著,引起皮质醇、睾酮降低,同时甲状旁腺素增高;而对血清胃泌素无明显影响。力竭性运动对机体脏器损伤有一定影响。     

Effects of a blood flow restriction exercise under different pressures on testosterone,growth hormone,and insulin-like growth factor levels

ObjectiveTo investigate the changes in serum growth hormone (GH), testosterone, and insulin-like growth factor 1 (IGF-1) during low-intensity resistance exercise under different cuff pressures.MethodsWe performed a single-blind, cross-over design study. Twenty-five healthy young men performed three exercise protocols as follows: 1) no blood flow restriction exercise (control group), 2) resistance exercise at 40% of arterial occlusion pressure (AOP) (low group), and 3) resistance exercise at 70% of AOP (high group). Blood lactate, GH, testosterone, and IGF-1 levels were measured at four time points.ResultsThere were no differences in the indices before exercise. The blood flow restriction exercise under different pressures had different effects on each index and there was an interactive effect. GH levels were significantly higher in the high group than in the other groups after exercise. Immediately after exercise, IGF-1 and testosterone levels were significantly higher in the high group than in the other groups. At 15 minutes after exercise, testosterone levels were significantly higher in the high group than in the other groups.ConclusionsLow-intensity resistance exercise combined with blood flow restriction effectively increases GH, IGF-1, and testosterone levels in young men. Increasing the cuff pressure results in greater levels of hormone secretion.     

Acute eccentric resistance exercise decreases matrix metalloproteinase activity in obese elderly women

The association of ageing with obesity commits elderly women and has been correlated with multiple degenerative processes, which could be occasioned by an enhancing in levels of matrix metalloproteinase‐2 and metalloproteinase‐9 (MMPs) as well by an cytokine unbalance that included an enhancing on interleukin‐6 (IL‐6). Furthermore, other factors could be also related to degenerative process, as they could be reduced by eccentric resistance exercise (ERE), which seems particularly important to initiate resistance training in obese older adults. In this view, this study aims to determinate the effects of an acute ERE session on serum MMP‐2, MMP‐9 and IL‐6 in elderly obese women. Ten elderly obese women participated in this study and completed a 10 repetitions maximum test (10 RM) utilizing leg extension exercise. Subjects then completed an acute ERE session consisting of seven sets of 10 repetitions at 110% of 10 RM with a rest of 3 min between sets. Blood samples were collected before, immediately after, 3, 24 and 48 h following the ERE session. Zymograms were utilized to measure the MMP‐2 and MMP‐9 enzymes from all individuals. Moreover, IL‐6 concentration was also determinated. After ERE session, MMP‐2 and MMP‐9 decreased, remaining significantly below baseline values after 48 h (P<0·05). Although not statistically significant, there was a tendency for IL‐6 to decrease 48 h after the ERE when compared with 3 h (P = 0·06). An acute ERE session decreases MMP‐9, MMP‐2 and IL‐6 in elderly obese women, possibly indicating a transient protection against the low grade inflammation present in this specific population.     

Haematological and hormonal responses to dynamic exercise in patients with chronic airway obstruction

The influence of exercise on hormonal and total white blood cells (WBC), lymphocytes (L). Granulocytes (GR), and platelet (P) count responses was studied in: twenty-five patients with chronic airway obstruction (CAO, 47 +/- 1.8 years, mean +/- SEM) and thirteen normal subjects (N, 36 +/- 2.6 years). They performed a submaximal (40 W) and a maximal exercise (VO2max). Arterial blood samples were taken at rest, 40 W, and VO2max. [H+], PaCO2, PaO2 haematocrit (Hct), [Hb], P, total platelet volume (TPV), WBC, GR, L, and total red blood cells (RBC) were measured. At rest, WBC, GR, P and TPV were higher in CAO patients, whilst PaO2 and cortisol were lower. At 40 W, when compared to values obtained at rest, WBC, GR, L, P and TPV were increased in both groups; WBC, GR, P and TPV were higher in CAO patients. VO2max of CAO patients represented 54% of that of controls. At VO2max, Hct, [Hb] and RBC were approximately 10% higher than at rest in both groups, whilst changes were more significant in normals for WBC (CAO = 55%, N = 76%), lymphocytes (CAO = 83%, N = 105%), GR, (CAO = 37%; N = 51%), platelets (CAO = 23%, N = 29%), TPV (CAO = 25.4%, N = 35%), [H+] (CAO = 43%, N = 38%) and ACTH (CAO = 82%, N = 139%). PaO2 and cortisol did not differ between groups. PaCO2 and platelets however, were higher in the CAO group.(ABSTRACT TRUNCATED AT 250 WORDS)     

Relationship between plasma endothelin-1 concentration and cardiovascular responses during high-intensity eccentric and concentric exercise

The present study investigates the relationship between plasma endothelin-1 (ET-1) concentrations and cardiovascular responses during eccentric (ECC) and concentric (CON) resistance exercises. Eight healthy males (aged 24.3 +/- 1.2 years) performed dynamic forearm exercises for 60 s at an angular velocity of 60 masculine s(-1). Each test comprised 60-s high-intensity (80% of peak torque) bouts of randomly selected ECC and CON contractions, and the plasma ET-1 concentrations were measured before and after each type of contraction. Systolic pressure (SBP), diastolic pressure (DBP), pulse pressure and heart rate (HR) during ECC and CON contraction were also measured. Mean arterial pressure (MAP) was calculated from SBP and DBP. The rate-pressure product (RPP) was calculated from SBP and HR. The plasma ET-1 concentration was significantly increased after CON, compared with ECC contraction (P<0.01). Moreover, SBP, DBP, MAP and RPP were significantly increased (P<0.05, P<0.01, P<0.001, respectively) during CON, compared with ECC contraction. Correlations between plasma ET-1 concentration and MAP were not significant during ECC contraction, but significantly positive during CON contraction (P<0.05). These results showed that CON contraction is associated with ET-1 production and a greater increase in blood pressure compared with ECC contraction.     

急性离心运动后恢复期大鼠骨骼肌微管形态及自噬体降解特征研究

目的:观察急性离心运动后恢复期大鼠骨骼肌微管形态变化及自噬体降解特征.方法:SD大鼠随机分为安静组、急性离心运动组,于运动后0h、12h、24h、48h、72h取材.分离单根肌纤维检测微管形态,Western Blot检测LC3、p62蛋白表达,腹腔注射秋水仙碱检测恢复前期(12h内)骨骼肌自噬流.结果:①急性离心运动...     

Using first bout effect to study the mechanisms underlying eccentric exercise induced force loss

Introduction

The first bout of eccentric exercise is known to have a protective effect on the consequent bouts. This effect is still disputable as it is not known whether it protects muscle damage by reducing force production or by improving force recovery in the healing process. The underlying mechanisms of this protective effect have not been fully understood.

等张运动和抗阻运动对心血管反应及相关激素的影响

目的 :比较等张运动和抗阻运动对心血管反应及儿茶酚胺激素的影响 ,探讨采用心率作为以等长运动形式为主的抗阻运动的强度指标的可能性。方法 :采用相同靶心率和相同运动时间对 8例健康男性分别进行等张运动和交替式抗阻运动 ,观察运动前后的心率、血压及儿茶酚胺的应激反应。结果 :两种运动后收缩压和两项乘积均显著增高 ,等张运动时脉压差明显增大 ,抗阻运动则表现为平均动脉压的升高 ,肌肉收缩力与心率呈直线性相关。去甲肾上腺素和多巴胺在两种运动后均显著增高 ,抗阻运动时升高尤为明显。运动前后血浆肾上腺素均无显著改变。结论 :心率作为运动强度的指标也适用于交替式抗阻运动 ,不同运动种类和强度影响儿茶酚胺的分泌程度     

不同负荷运动量对血清睾酮、游离睾酮和皮质醇浓度的影响

目的 :探讨不同负荷运动量对血清睾酮 (T)、游离睾酮 (FT)和皮质醇 (C)浓度的影响。方法 :对16名摔跤运动员训练当日晨 ,训练前 ,训练后即刻 ,次日晨和再次日晨抽取血液标本。结果 :小强度训练变化不明显 ,中、大强度训练前后血清T、FT和C均有明显变化。结论 :血清T、FT和C可作为观察运动量的指标。     

等速离心训练对膝关节骨关节炎患者的影响

目的探讨等速离心肌力训练对膝关节骨关节炎患者的康复疗效。方法运用Cybex-6000型等速肌力测试及训练系统对40例膝关节骨关节炎患者(共70个患膝)进行为期4周、每周3次的等速离心肌力训练。分别于训练前、后测定患者在60°/s、120°/s及180°/s等速运动时的峰力矩、单次最大作功量、平均功率及力矩加速能量;并将训练前、后患膝疼痛程度及下肢功能评分进行比较。结果患者经训练后,其患膝屈、伸肌群各项功能参数均有显著改善,并以屈膝肌各项功能参数的改善尤为显著;患膝疼痛及功能性行为能力评分亦均较治疗前有显著改善。结论等速离心训练能有效改善膝关节骨关节炎患者屈、伸肌群的各项功能参数(其中以屈膝肌的改善尤为显著);同时还能缓解患者疼痛,显著提高其功能性行为能力。     

Physiological characteristics and hormonal profile of young normotensive men with exaggerated blood pressure response to exercise

Exaggerated blood pressure (BP) response to exercise in normotensive subjects is considered as a predictor of future hypertension. The aim of the study was to find out whether elevated BP response to exercise is associated with any other haemody-namic, metabolic or hormonal abnormalities. Abnormal BP response to exercise, i.e. systolic BP (SBP)>200 mmHg at 150 W or lower workload, was found in 37 out of 180 normotensive, male students, aged 20–24 years. Fifteen students with elevated exercise BP (group E) volunteered for further examinations. Their resting and ambulatory BP showed high normal values. Eight of them had a family history of hypertension. Four subjects met the criteria of cardiac hypertrophy. Significant correlations were found between exercise SBP and left ventricular mass index, average 24 h and daytime SBP recordings. In comparison with normal subjects of the same age (group N, n=13), those from group E did not differ in body mass index, plasma lipid profile, fasting glucose, insulin and catecholamine (CA) concentrations, but had increased erythrocyte sodium content, slightly elevated plasma renin activity and cortisol level. During exercise, E subjects showed greater cardiac output (CO) increases with normal heart rate, total peripheral resistance (TPR) and plasma CA. There were no significant differences between groups in haemodynamic and plasma CA responses to posture change from supine to standing. Glucose ingestion (75 g) caused smaller increases in CO and smaller decreases in TPR in E than in N subjects without differences in BP, blood glucose, plasma insulin and CA. It is concluded that young normotensive men with exaggerated BP response to exercise show some other characteristics that may be considered as markers of predisposition to hypertension or factors promoting the development of hypertension.     

Ghrelin and glucoregulatory hormone responses to a single circuit resistance exercise in male college students

INTRODUCTION: It has been suggested that ghrelin may play a role in growth hormone (GH) secretion to exercise. OBJECTIVE: The present study was designed to examine the effects of a single bout of circuit resistance exercise on plasma glucose, ghrelin, GH, and c-peptide, and cortisol. DESIGN AND METHODS: Fourteen volunteer male physical education students completed a single bout circuit resistance training (10 exercises, three circuits, and at 60% of 1-RM). Blood samples were collected before, immediately after the exercise, and 24-h following the exercise protocol. RESULTS: GH, glucose, and c-peptide showed a significant increase immediately after exercise and returned to pre exercise values over time. Plasma ghrelin showed a significant decrease immediately after the exercise and increased significantly 24-h following the exercise. CONCLUSION: In conclusion, a decrease in plasma ghrelin following a single bout of circuit resistance exercise indicates that an increase in GH is not related to plasma ghrelin levels. An acute exercise-induced hyperphagia during the long-recovery was considered.     

离心跑台运动对小鼠骨骼肌炎性因子、肌再生因子及血管再生因子表达的影响

目的:观察小鼠离心运动后骨骼肌炎性因子、肌再生因子以及血管再生因子的表达变化,探讨其在离心运动骨骼肌损伤修复中可能发挥的作用。方法:32只雄性C57BL/6小鼠随机分为对照组(C组,n=8)和离心运动组(D组,n=24)。根据取材时间,离心运动组又分为3个小组(运动后1d,3d和7d组)。离心运动后不同时间点取双侧腓肠肌。HE染色观察骨骼肌形态学变化,比色法检测血浆肌酸激酶(CK)和乳酸脱氢酶(LDH)活性,荧光定量PCR检测炎性因子、肌再生因子及血管再生因子基因表达的变化。结果:小鼠下坡跑后骨骼肌纤维结构无明显破坏,无显著炎性细胞浸润。与对照相比,血浆CK和LDH活性在运动后各时间点均无显著变化(P0.05)。从基因层面看,炎性细胞标志物(MPO—嗜中性粒细胞标志物;F4/80—巨噬细胞标志物)在下坡跑后显著上升。部分炎症因子(如肿瘤坏死因子-α、白介素-1β、白介素-6)在下坡跑后显著上调。而肌再生调节因子中,只有机械生长因子和白血病抑制因子在运动后出现显著上调。而肌再生关键细胞——肌卫星细胞的特异性标记分子(分子标志—Pax7,增殖标记—Myo D,分化标记—myogenin)在离心运动后未出现显著变化(P0.05)。此外,其他与肌肉和血管再生密切相关的再生因子(如:胰岛素样生长因子1、肝细胞生长因子、尿激酶型纤溶酶原激活物、环氧合酶2、低氧诱导因子-1α、血管内皮生长因子、血管生成素1等)在离心运动后均未见显著变化(P0.05)。结论:从形态学表现、血清指标和基因表达综合来看,离心跑台运动并非小鼠骨骼肌损伤建模的理想方式。     

Haemodynamic and hormonal responses to exercise: Studies in patients with diabetes mellitus and adrenomedullary deficiency

The haemodynamic and hormonal responses of patients with autonomic neuropathy and others with adrenomedullary deficiency were compared with mild hypertensives (range of blood pressure 90-100 mmHg diastolic and 140-160 mmHg systolic) and uncomplicated diabetics during standard exercise and postural manoeuvres using continuous arterial blood pressure monitoring. There was no difference in these parameters between the groups when at rest or on standing. During exercise there was no significant difference in blood pressure and heart rate between the groups and all showed significant increases in plasma noradrenaline (mean rise for all groups 2730-22 105 pm 1(-1), P less than 0.03) and (in all but the adrenalectomized subjects) adrenaline (mean rise for remaining three groups 946-3384 pm 1(-1), P less than 0.03; adrenalectomized group showed no rise). The group with autonomic neuropathy showed a significant rise in plasma cortisol from basal 450 +/- 40 to 845 +/- 72 nm 1(-1), P less than 0.005 after exercise, but the other groups showed no significant change. The maximum level attained for plasma cortisol in the adrenalectomized subjects after exercise was significantly less (260 +/- 41 nm 1(-1) than in the diabetic groups (696 +/- 68 nm 1(-1) (non-neuropaths), 845 +/- 72 nm 1(-1) (neuropaths), P less than 0.01). We have demonstrated normal blood pressure and pulse responses to posture and sustained exercise in diabetics with autonomic neutropathy. The findings of similarly normal responses in patients with adrenomedullary deficiency suggest that circulating adrenaline is not obligatory to a normal haemodynamic response to exercise.     

Pancreatic and pituitary hormonal responses to insulin-induced hypoglycaemia during muscarinic cholinergic blockade in man

To investigate the role of muscarinic cholinergic mechanisms in mediating the pancreatic and pituitary hormonal responses to hypoglycaemia, six normal subjects were studied during acute insulin-induced hypoglycaemia under control conditions, and during blockade with intravenous atropine. During atropine blockade the response of pancreatic polypeptide was suppressed while the maximum response of plasma glucagon was significantly higher. The increment in plasma vasopressin was also increased significantly during cholinergic blockade. During blockade with atropine the responses of plasma prolactin was reduced, with a slight but significant reduction in the growth hormone response, and although a similar maximum response of plasma ACTH was achieved, this rise was delayed. These results implicate involvement of a cholinergic muscarinic inhibitory and stimulatory mechanisms in regulating the responses of pancreatic and pituitary hormones to hypoglycaemia.     

Metabolic and anti-inflammatory benefits of eccentric endurance exercise - a pilot study

Background Eccentric endurance exercise (e.g. hiking downwards) is less strenuous than concentric exercise (e.g. hiking upwards) but its potential to reduce cardiovascular risk is unknown. Materials and methods We randomly allocated 45 healthy sedentary individuals (16 men and 29 women, mean age 48 years) to one of two groups, one beginning with two months of hiking upwards, the other with two months of hiking downwards the same route, with a crossover for a further two months. For the opposite way, a cable car was used where compliance was recorded electronically. The difference in altitude was 540 metres; the distance was covered three to five times a week. Fasting and postprandial metabolic profiles were obtained at baseline and after the two month periods of eccentric and concentric exercise, respectively. Results Forty‐two of the 45 participants completed the study; the compliance rate was therefore 93%. Compared with baseline, eccentric exercise lowered total cholesterol (by 4·1%; P = 0·026), low‐density lipoprotein (LDL) cholesterol (by 8·4%, P = 0·001), Apolipoprotein B/Apolipoprotein A1 ratio (by 10·9%, P < 0·001), homeostasis model assessment of insulin resistance scores (by 26·2%, P = 0·017) and C‐reactive protein (by 30·0%; P = 0·007); the magnitude of these changes was comparable to that of concentric exercise. Eccentric exercise improved glucose tolerance (by 6·2%, P = 0·023), whereas concentric exercise improved triglyceride tolerance (by 14·9%, P = 0·022). Conclusions Eccentric endurance exercise is a promising new exercise modality with favourable metabolic and anti‐inflammatory effects and is well applicable to sedentary individuals.     

Effects of physical exercise on serum calcium and parathyroid hormone

The effects of physical exercise on plasma ionized calcium, total serum calcium and parathyroid hormone (PTH) concentrations were evaluated in healthy subjects submitted to work on an ergometer bicycle. When the workload was increased stepwise there was a significant increase (P less than 0.001) in the calcium concentrations (ionized calcium from 1.13 +/- 0.03 (SD) to 1.24 +/- 0.03 mmol 1(-1) and total calcium from 2.35 +/- 0.07 to 2.48 +/- 0.07 mmol 1(-1] when the workload exceeded approximately 65% of the estimated maximum--i.e. a load that caused accumulation in blood of lactic acid. The rise in plasma ionized calcium was, therefore, presumably largely attributed to the acidosis but reduction of plasma volume and influx from extracellular sources might also have contributed. Beta blockade (with oral intake of propranolol) reduced physical capacity, shortened the duration of work and caused less acidosis. These factors were probably responsible for a smaller rise in ionized calcium during beta blockade (7 +/- 4%) than in control studies (21 +/- 5%) without medication in subjects examined during short-term maximal exercise. Long-term (1 h) steady-state work which caused fatigue without producing lactic acidosis did not affect the calcium concentrations. Despite the effects of work on calcium levels there was no discernible suppression of the PTH concentrations. This might have been due to a concomitant stimulation of PTH secretion by work.