Effect of sleep deprivation on tolerance of prolonged exercise

Summary Acute loss of sleep produces few apparent physiological effects at rest. Nevertheless, many anecdotes suggest that adequate sleep is essential for optimum endurance athletic performance. To investigate this question, heavy exercise performance after 36 h without sleep was compared with that after normal sleep in eight subjects. During prolonged treadmill walking at about 80% of the max, sleep loss reduced work time to exhaustion by an average of 11% (p=0.05). This decrease occurred despite doubling monetary incentives for subjects during work after sleeplessness. Subjects appeared to fall into “resistant” and “susceptible” categories: four showed less than a 5% change in performance after sleep loss, while four others showed decrements in exercise tolerance ranging from 15 to 40%. During the walk, sleep loss resulted in significantly greater perceived exertion (p<0.05), even though exercise heart rate and metabolic rate ( and ) were unchanged. Minute ventilation was significantly elevated during exercise after sleep loss (p<0.05). Sleep loss failed to alter the continuous slow rises in _E and heart rate that occurred as work was prolonged. These findings suggest that the psychological effects of acute sleep loss may contribute to decreased tolerance of prolonged heavy exercise. Supported in part by Public Health Service grant PHS S07 RR 5371, and by Grant DAMD-17-81-C-1023 from the U.S. Army     

Einflu\ eines Β1-Rezeptorenblockers auf die Plasmaspiegel des atrialen natriuretischen Peptids bei Patienten mit essentieller Hypertonie unter Ergometerbelastung

Summary In order to investigate the behaviour of atrial natriuretic peptide (ANP) in untreated mild to moderate essential hypertension and the influence of blood pressure normalisation by a ₁-receptor blocker a study was conducted in groups of normotensive and hypertensive middle aged subjects. 10 normal subjects and 10 patients with essential hypertension (WHO I–II) without any medication and on betaxolol monotherapy were studied at rest and during graded exercise. In addition the response of ANP, cyclic guanosine monophosphate (cGMP) and the renin-aldosterone-system was investigated.Normal subjects and hypertensive patients did not differ in ANP levels at rest and also responded with a comparable exercise dependent increase at all workload levels. A steady decrease of ANP was noticed during the recovery period in both groups. After-blocker treatment in the hypertensive patients ANP concentrations significantly rose, both at rest and more pronounced during exercise. cGMP reacted in a similar way but showed a more inert response. A counter-regulatory behaviour between ANP and PRA or aldosterone, as seen under volume shifts, could not be detected. These findings demonstrate that plasma ANP is not altered in untreated essential hypertension. Increased ANP levels in ₁-blocker treatment may contribute to its blood lowering effect.

---

Abkürzungsverzeichnis ANP atriales natriuretisches Peptid - ALD Aldosteron - C_In Inulin Clearance - cGMP zyklisches Guanosinmonophosphat - irANP immunoreaktives atriales natriuretisches Peptid - PAH Paraaminohippursäure - PRA Plasma-Renin-Aktivität - RAA-System Renin-Angiotensin-Aldosteron-System - RBF renaler Blutflu - RIA Radioimmunoassay - RVR renaler Gefä\widerstand     

溴化异丙托品对稳定期COPD患者肺功能及运动耐受性的影响

目的 观察不同剂量的溴化异丙托品（ＩＰＢ）短时及长期应用,对稳定期慢性阻塞性肺疾病（ＣＯＰＤ）患者的肺功能及运动耐受性的影响。方法 ３７例稳定期ＣＯＰＤ患者,随机分３组,分别吸人ＩＰＢ１６０μｇ／次、８０μｇ／次、４０μｇ／次。用药前后行肺功能及自行车功量仪极量运动负荷法运动试验测验。结果 吸入ＩＰＢ１６０μｇ／次、８０μｇ／次组与安慰剂对照组相比,通气及运动指标均明显改善（Ｐ〈０．０１、Ｐ〈０．     

The Effects of 10 Weeks Military Training on Heel Ultrasound and Bone Turnover

To measure the physiological changes in bone in response to strenuous exercise we performed a prospective study of male army recruits over 10 weeks of basic training. Measurements performed at the start and completion of training consisted of ultrasound (US) measurements of the heel: velocity of sound (VOS in m/seconds) and broadband ultrasound attenuation (BUA in dB/MHz) and bone turnover markers; osteocalcin (OC), bone-specific alkaline phosphatase (BALP), and tartrate-resistant acid phosphatase (TRAP). Forty subjects were recruited for the study and 26 completed training. Over the 10-week study period there was a significant 1.7% fall in mean VOS [mean paired difference (mpd) 27.2 m/second, SEM 9.5 (95% CI 7.5–46.8) P= 0.009] and a nonsignificant 3.4% increase in BUA (P= 0.159). There were significant falls in markers of bone formation OC [11.6%, mpd 0.11 μg/liter (95% CI 0.07–0.14) P < 0.001] and BALP [13.3%, mpd 3.49 U/liter (CI 0.80–6.18) P= 0.013] and a nonsignificant 9.5% fall in TRAP a marker of bone resorption. The 10 recruits subsequently injured had a significantly lower VOS on entry [mean difference 24.2 m/seconds (95% CI 4.6–43.7) P= 0.017] and nonsignificantly raised BUA and baseline levels of all bone markers. The ultrasound changes may be accounted for by increase in trabecular separation and a fall in trabecular connectivity due to microfracture. The decrease in bone markers implies a fall in bone turnover. Received: 26 June 1997 / Accepted: 26 August 1998     

Regulation of PaCO2 during rest and exercise: A modeling study

A nonlinear mathematical model of the CO₂ control system was used to examine a number of issues concerning the regulation of PaCO₂ during rest and exercise. To gain insight to the regulatory properties of the respiratory system, the open loop gain (G_l) and closed loop sensitivities S_i=ξPaCO₂/ξPiCO₂ and were calculated. Gl indicates the ability of a control system to regulate the controlled variable, PaCO₂ in the model. Si and Sv represent the change in PaCO₂ to unit changes in PiCO₂ and , respectively. Model predications were obtained for rest and various intensities of exercise for the following challenges to the respiratory system: (a) CO₂ inhalation, (b) i.v. CO₂ loading, (c) application of an external dead space, and (d) a shift in the resting operating point. Increasing exercise intensity produced a substantial decrease in Gl and increase in Si consistent with the hypothesis that exercise degrades the ability of the respiratory system to regulate PaCO₂. However, Sv decreased indicating that the respiratory system would actually be better able to regulate PaCO₂ if there were fluctuations in . Thus, Gl does not completely describe the regulatory characteristics of the respiratory control system. It is demonstrated that the regulatory characteristics of the respiratory system as described by Gl, Si, and Sv are complex and depend on the nature of the challenge. Techniques for systematically describing the regulatory properties of the CO₂ control system are described.     

Continuous monitoring of extracellular lactate concentration by microdialysis lactography for the study of rat muscle metabolism in vivo

A method is described for the measurement and on-line monitoring of muscular extracellular lactate concentration in both anaesthetized and freely moving rats. This method is based on microdialysis sampling and lactic dehydrogenase-catalysed nicotinamide adenine dinucleotide, reduced (NADH)-fluorescence detection techniques. In vivo calibration revealed a resting extracellular lactate concentration of 1.92±0.13 mmol/l (± SEM) in the gastrocnemius muscle of adult male Wistar rats (n=6), while the average whole-blood lactate level was 0.76±0.12 mmol/l (± SEM). This measured extracellular lactate concentration was 1.73-times higher than that deduced from the arterial lactate concentration. Blocking glycolysis with iodoacetate reduced the extracellular lactate concentration to 52±6% (± SEM, n= 4) of the resting level. The extracellular lactate concentration in rat gastrocnemius muscle had increased to significantly (P0.05) different levels, 2.4±0.03 (± SEM) or 4.0±0.55 (± SEM) times the control value, 1 h after aortic clamping (n=3) or cardiac arrest (n=3), respectively. Stimulation of the sciatic nerve induced elevations of the extracellular lactate concentration in the tibialis anterior muscle which were linearly related to the recorded isometric force-time integral. We also monitored on-line the changes in extracellular lactate concentration in the tibialis anterior muscle of a swimming rat. Our results indicate that microdialysis lactate reflects also intracellular metabolism. Lactography may be a useful alternative to biopsies and nuclear magnetic resonance spectroscopy in clinical medicine and physiology for the monitoring of metabolism in vivo.     

浅谈针刺手法的基本功锻炼

针刺手法的运用是针灸临床治疗的一个关键环节。针刺手法的基本功锻炼是提高针刺手法操作技术的重要途径。本文详细介绍了针刺手法基本功锻炼的步骤和方法。     

Physical performance in long-term survivors of acute leukaemia in childhood

The aim of this study was to assess the physical performance in long-term survivors of acute leukaemia in childhood and to evaluate the effects of anthracycline therapy. Electrocardiography, echocardiography and spiroergometry were carried out on 56 patients aged 9–28 years, of whom 44 patients had been treated with 15–483 mg/m² doxorubicin (or equivalent). Acute leukaemia had been diagnosed 1.5–16 years earlier. Of the patients 75% reached normal maximal oxygen uptake, 69% normal oxygen uptake at the anaerobic threshold and 95% normal maximal work rate. Of the patients 75% achieved adequate values for maximal heart rate and 78% normal blood lactate concentration. No difference was seen between patients treated with and without anthracyclines. Conclusion The results of this study provide little evidence for cardiopulmonary impairment in long-term survivors of ALL. Both the cardiac function, as evaluated by ECG and echocardiography, and the physical performance in spiroergometry are normal in a large number of these patients. Anthracycline treatment does not appear to have a negative effect on these parameters. Received: 30 October 1996 / Accepted in revised form: 7 October 1997     

A pilot study using magnetic resonance imaging to determine the pattern of muscle group recruitment by rowers with different levels of experience

Objective. To determine whether it was possible using magnetic resonance imaging (MRI) to define the pattern of muscle recruitment in a specific sport (rowing) and to see whether there were differences in this pattern between athletes of different experience. Design and method. It has been shown that during vigorous exercise the water content of muscle increases transiently. This can be observed using MRI, where the prolonged T2 relaxation time of muscle can be demonstrated. In this study we have exploited the increase in signal seen in exercised muscle on short TI inversion recovery (STIR) sequences, to show how rowers of different experience use different muscle groups. Results.We have shown that trained athletes recruit selected muscle groups to carry out a given task, which they carry out more efficiently than untrained or less experienced athletes. Conclusion.We have provided the basis of potential research to refine training methods, in order to develop specific muscle groups in athletes, in the hope of achieving a higher level of performance at an earlier stage in their training. We have also defined a technique that may be of clinical value in cases of muscle dysfunction. Received: 13 September 1999 Revision requested: 19 November 1999 Revision received: 30 December 1999 Accepted: 4 January 2000     

维持性血液透析患者自我管理与运动自我效能及运动水平的相关性

目的 探讨维持性血液透析（MHD）患者自我管理水平与运动自我效能及运动水平的相关性。方法 采用横断面调查方式,对我院2018年1月～2018年5月的199例MHD患者,采用自行设计的一般资料调查表、自我管理量表、运动自我效能量表（ESE）及运动水平量表进行调查,并使用SPSS 17.0软件进行统计分析。结果 MHD患者自我管理与运动自我效能之间呈正相关（r=0.419,P＜0.05）;自我管理与运动水平亦呈正相关（r=0.348,P＜0.05）。结论 MHD患者自我管理与运动自我效能及运动水平息息相关,应有效干预MHD患者自我管理与运动自我效能及运动水平,进而提高MHD患者的临床疗效。