カナダ,アメリカ合衆国における大学院での理学療法学教育について

広島大学大学院保健学研究科 第1回国際シンポジウ

Weyl Starobinsky inflation

In Starobinsky inflation with a Weyl squared Lagrangian $-\alpha C^2$, where $\alpha$ is a coupling constant, we study the linear stability of cosmological perturbations on a spatially flat Friedmann-Lema\^{i}tre-Robertson-Walker background. In this theory, there are two dynamical vector modes propagating as ghosts for $\alpha>0$, whose condition is required to avoid tachyonic instabilities of vector perturbations during inflation. The tensor sector has four propagating degrees of freedom, among which two of them correspond to ghost modes. However, tensor perturbations approach constants after the Hubble radius crossing during inflation, and hence the classical instabilities are absent. In the scalar sector, the Weyl curvature gives rise to a ghost mode coupled to the scalaron arising from the squared Ricci scalar. We show that two gauge-invariant gravitational potentials, which are both dynamical in our theory, are subject to exponential growth after the Hubble radius crossing. There are particular gauge-invariant combinations like the curvature perturbations whose growth is suppressed, but it is not possible to remove the instability of other propagating degrees of freedom present in the perturbed metric. This violent and purely classical instability present in the scalar sector makes the background unviable. Furthermore, the presence of such classical instability makes the quantization of the modes irrelevant, and the homogeneous inflationary background is spoiled by the Weyl curvature term.Comment: 24 pages, 3 figure

Is Work Sharing Effective? (Japanese)

Calls for work sharing are always made whenever employment conditions worsen. However, the hurdle for creating employment through work-sharing is very high. The reasons are as follows: (1) wage cuts by mutual agreement based on a relationship of trust between labor and management is necessary (the first hurdle in work sharing), and (2) the introduction of work sharing is limited to workplaces where the substitution of working hours and workers is easy and the fixed costs required for recruitment and training are low (the second hurdle in work sharing). Even rigorous empirical analyses overseas show that it is extremely rare for work sharing to actually function, and Kawaguchi, Naito and Yokoyama (2008) identify a similar trend in Japan. Work sharing is never a magic wand to overcome an employment crisis and we should not place excessive expectations on it. Given the limitations of private sector-driven work sharing, public sector-driven work sharing, such as an employment adjustment subsidy, may be more effective to maintain employment, as a source of funds is ensured. However, a policy response is necessary to nail down the cost-benefit performance of work sharing and avoid distorting the market adjustment mechanism, which is a driving force for smooth flow of the workforce and industrial structure adjustment.

Changes of Agonist and Antagonist Spinal Motor Neurons Excitability by Muscle Fatigue : analysis of H-reflex and M waves of evoked electromyogram

本研究では, 筋疲労に伴う主動筋および拮抗筋脊髄運動ニューロン興奮性の変化を明らかにするため, 等尺性足関節底・背屈運動前後のヒラメ筋H波およびM波の経時的な変化を観察した。対象は健康な男子10名とし, 最大随意筋収縮(MVC)の50%の足関節等尺性運動を行った。その結果, (1)底屈運動によるヒラメ筋の疲労後, Hmax/Mmax(最大H波とM波の振幅比)は, 安静時と比較して57.37±12.97%に低下し, この低下は運動終了30分後においても74.90±10.89%であった。このことから, 筋疲労に伴い, 筋を支配する脊髄運動ニューロンが長時間抑制されることが示唆された。(2)背屈運動による前脛骨筋の疲労後, 拮抗筋であるヒラメ筋のHmax/Mmaxが, 安静時と比較して70.13±8.85%に低下した。運動終了後, 徐々に回復し, 8分程で安静時のレベルに回復した。(3)前脛骨筋の疲労後, 拮抗筋であるヒラメ筋のHthr(H波閾値)は安静時と比較して有意に増加した。(2)と(3)により, 主動筋の疲労によって, 主動筋のみならず運動を行っていない拮抗筋脊髄運動ニューロンも抑制を受けていることが明らかになった。This study examined the chronological changes of H-reflex and M waves in soleus muscle before and after fatigue induced by isometric ankle joint plantar/dorsal flexion to clarify the changes of agonist/antagonist spinal motor neurons excitability involved in muscle fatigue. Subjects were 10 healthy males who performed ankle joint isometric exercise at 50Invalid or incomplete multibyte or wide characteraximum voluntary contraction (MVC). Results were : (1) After plantar flexion caused soleus muscle fatigue, the soleus muscle Hmax/Mmax (amplitude ratio between maximum H-reflex and M waves) stayed at a low value for a long time. (2) After dorsal flexion caused tibialis anterior muscle fatigue, the soleus muscle (antagonist) Hmax/Mmax fell to 70.13±8.850f the resting value and then gradually recovered. (3) After the tibialis anterior muscle fatigue, the soleus muscle (antagonist) Hthr (H-reflex threshold) significantly increased as compared with the resting value. Results (2) and (3) showed that the agonist's fatigue inhibits not only the agonist but also non-exercised antagonist spinal motor neurons

Influence of mild hypoxia on cardiorespiratory responses and muscle oxygenation during incremental exercise

This study investigated the influence of cardiorespiratory responses, blood lactate concentration and muscle oxygenation during incremental exercise tests in normoxia and hypoxia. Seven healthy subjects performed an incremental cycle ergometer exercise test breathing in random order either room air or a 15% O2 gas mixture. Ventilation and pulmonary gas exchange were measured and computed breath-bybreath. Arterial oxygen saturation (SaO2) was estimated continuously via pulse oxymeter. Forearm venous blood for measurement of blood lactate was collected every minute. Continuous-wave near infrared spectroscopy measured peripheral tissue saturation (SO2NIRS) in the vastus lateralis muscle. Significant reduction in oxygen uptake (p<0.01), power output (p<0.01) and SaO2 (p<0.001) was found in peak incremental exercise during hypoxia compared with normoxia. For the same power output in the twoconditions, hypoxia significantly decreased SaO2 (ANOVA: p<0.001) and blood lactate concentration (ANOVA: p<0.05) and increased minute ventilation (ANOVA: p<0.01). In the hypoxic condition, oxygen uptake and SO2NIRS were not found when exercising at the same power output compared with normoxia. This study would suggest that mild hypoxia may be avoided through ventilatory compensation at the alveolar level, and oxygen consumption in alveolar and peripheral tissue oxygenation can be maintained while exercising for the same power output

The effect of clonus and muscle spasm on cardiovascular responses in patients with quadriplegia

頚髄損傷者にみられるクローヌスや筋痙攣が循環動態に与える影響について検討することを目的とした.対象者はC7レベルでの男性頚髄損傷者2名(症例1:年齢41歳;身長172 cm;体重55kg;罹病年数;10年)とし,損傷レベル以下での感覚機能,運動機能ともに消失していた(ASIA gradeA).5分間の車椅子安静座位の後,対象者の麻痺域末梢部に求心性の刺激を加えクローヌスや筋痙攣を誘発した.その際,収縮期血圧(BP),1回拍出量(SV),心拍出量(CO),全末梢血管抵抗値(TPR),心拍数(HR),腓腹筋部ヘモグロビン量(TotalHb),心拍変動高周波成分(HF),腓腹筋筋電図を記録した.刺激により腓腹筋の収縮が筋電図により確認された.症例1ではBP, HR, CO, TPR,HF が増加したが,SV は安静時の80%まで減少した.症例2ではBP, SV, CO,HFは増加した.さらにHRは刺激を加えた直後に,いったん安静時の150%まで増加した後,安静時の75%まで減少した.TPRは安静時の60%まで減少した後,安静時の150%まで増加した.また,TotalHbは両症例ともに変化しなかった.したがって,クローヌスや筋痙攣の出現とともに循環動態に変化がもたらされ血圧が上昇することが示され,末梢部の求心性刺激によるクローヌスや筋痙攣は脊髄内に異常興奮を生じ,反射性の交感神経活動により心臓や血管に影響を与えたことが考えられた.The purpose of this study was to examine the effect of clonus and muscle spasm on the cardiovascularresponses of patients with cervical cord injury (CCI). Two males with a lesion at C7 volunteered for thisstudy (Case 1: age 44 years; height 172 cm; weight 55 kg; duration of injury 20 years. Case 2: age 31 years;height 171 cm; weight 50 kg; duration of injury 10 years.). The subjects showed no sensory or motor belowthe level of the lesion (ASIA grade A). Following a rest period of 5 minutes in the wheelchair, peripheralafferent stimulation was performed in subjects. Systolic arterial blood pressure (BP), stroke volume (SV),Cardiac output (CO), Total peripheral resistance (TPR), heart rate (HR), total hemoglobin of calf(TotalHb), high frequency of heart rate variability (HF), and electromyogram (EMG) of gastrocnemiuschanges were measured. In result, following the stimulation, contraction of gastrocnemius wererecognized with EMG. In case 1, BP, HR, CO, TPR and HF increased, whereas SV decreased by about80%.0In case 2, BP, SV, CO and HF increased. Immediately after stimulation, HR increased by about 150-0x1.fcfap+0nd then decreased by about 75%.0 TPR decreased by about 60-0x1.4b3a0b6a4aap-149nd then increased by about 150%.0 TotalHbshowed no change in either subject. These results suggested that clonus and muscle spasm inducedcircular reaction and a marked BP. Peripheral afferent stimulation during Clonus and muscle spasm that isinduced by intraspinal hypersthenia decentralized part of the sympathetic nervous system and influencedheart and blood vessels

Muscle oxygenation trend in patients with hypertensive type 2 diabetes mellitus

本研究は,2型糖尿病患者を高血圧合併の有無により分類し,運動筋酸素動態の差異を明らかにすることを目的とした.運動は,最大随意筋力の30%の強度にて3分30秒間の足関節底屈運動を行い,終了直前30秒間に一時的動脈血流遮断法を併用して,筋酸素利用変化率(%MO2)を算出し,運動終了後の筋酸素化レベル回復時間(TR)を測定した.その結果,高血圧合併2型糖尿病患者は,ヘモグロビンA1cおよび上腕動脈-足動脈間脈波伝播速度(baPWV)が有意に高値を示し(p<0.05),%MO2 に有意差は認められなかった.またTRは有意に延長し(p<0.05),baPWVとTRには有意な正の相関関係を認めた(r=0.58,p<0.05).以上のことから,高血圧合併2型糖尿病患者では,高血圧を合併しない糖尿病患者と比較して,中等度運動での筋酸素化レベルに差異は認められないが,動脈硬化により酸素供給が低下した結果,TRが延長することが明らかとなった.Background : It is known that hypertension with type 2 diabetes mellitus increases the risk of arterial stiffness, but it is not clear whether it is accompanied by abnormal oxygenation in the exercising muscle. Methods and results: A total of 50 patients with type 2 diabetes, comprising normotensive patients (n=34, Age:53.6±8.6, BMI:23.0±3.9) and hypertensive patients (n=16, Age:53.9±8.2, BMI:24.5±3.5) , was studied. Right gastronomies muscle oxygenation was measured using near-infrared spectroscopy while resting and in a 210 sec planter flexion exercise. Muscle oxygen utilization rate (%MO2) was calculated as the increasing rate of oxygenated hemoglobin/mymoglobin during a 30 sec arterial occlusion, and reoxygenation time (TR) was calculated after arterial occlusion. The results demonstrated that glycol hemoglobin A1c (HbA1c) and baPWV in hypertensive patients (HbA1c:7.5±1.2%, baPWV:1777.9±320.7 cm/sec) were significantly different from those in normotensive patients (HbA1c:6.7±0.8%, baPWV:1520.2±211.8 cm/sec)(p<0.05, p<0.001), while no difference was observed in %MO2. Moreover, the TR was found to be slower in the hypertensive patients, and showed a positive relationship with the baPWV (r=0.58, p<0.05). From these results, it could be concluded that the arterial stiffness was caused by the decrease of oxygenation and the prolonging of TR in the hypertension with type 2 diabetes patients

Discrimination of athletic characteristics based on exercise physiology and serum biochemistry

The purpose of the present study is to determine whether athletic characteristics can be discriminated by changes in serum components during exercise which are considered to reflect systemic endurance capacity, muscle strength, and the energy metabolism system. Thirteen male long-distance athletes and 8 male short-distance and field athletes performed an incremental exercise test, muscle strength, and endurance test. They were also observed for changes in serum components during exercise. According to data analysis, the discriminant function thus obtained was: Z=0.8220×peakVO2+0.0037×AT+0.0010×MVC+(-0.0276)×60deg/sec+0.2629×MVC500me+(-0.8715)×UN+36.1659(peakVO2: measured value of peak VO2, AT: 0xbfffa670eakVO2, MVC: measured value of the isometric muscle strength, 60deg/sec: peak torque of the isokinetic muscle contraction at 60deg/sec, MVC50-1230722560me: the time for the previously determined isometric muscle strength value to become less than 50%, UN: the increase rate of UN from the value at rest to the maximum value). Subjects were classified into the actual group correctly, while the erroneous discriminant rate was 0.73%.0 In particular, weighting of the discriminant coefficient of peakVO2 and UN was large, indicating that these are useful as parameters for discriminating athletic characteristics

糖尿病患者と健常者におけるR-R間隔変動係数は運動中の循環応答を反映するか?

糖尿病患者と健常者のR-R間隔変動係数(CVR-R)と運動時における循環応答との関連を検討した。対象は2型糖尿病患者8名と,年齢をマッチさせた健常男性8名とした。対象者に自転車エルゴメータを用いた漸増負荷を行い,最大酸素摂取量(・VO2max)と換気性作業閾値(VT)を算出した。次に日を改めて,80%VTに相当する負荷強度で一定負荷運動を行わせた。その後,安静時におけるCVR-Rと,一定負荷運動における酸素摂取と心拍数の時定数を算出した。その結果,1)CVR-Rと・VO2maxはDM群で健常群と比較して低下していた。また,tau HRとtau・VO2はDM群で延長していた。2)tau・VO2とtau HRは二群共に正の相関を,CVR-Rとtau ・VO2は二群共に負の相関を認めた。2・VO2maxとtau HR,・VO2maxとtau・VO2は健常群のみ負の相関を認めた。以上の結果から,CVR-Rは運動に対する循環応答を反映する指標になる可能性が示唆された。また,先行研究において,健常者では運動開始時における循環応答特性は全身持久力を反映するものであることが示唆されているが,本研究では糖尿病患者においては関連を認めないことが明らかとなった。OBJECTIVE: We investigated the relation of the coefficient of variation of the R-R intervals in diabetic patients and healthy subjects, and the cardiovascular responses during exercise. RESEARCH DESIGN AND METHOD: The subjects were 8 males with type 2 diabetes mellitus, and 8 age-matched healthy nondiabetic males (healthy controls). All subjects performed an incremental test on a bicycle ergometer at a work rate of 15 Watt・min-1 to determine the maximum oxygen uptake and to calculate ventilatory threshold. Subsequently, on another day, they all performed a constant-load exercise at a work rate chosen to elicit an oxygen uptake equivalent to 800f their individual the ventilatory threshold. The coefficient of variation of the R-R intervals (CVR-R) was calculated from the electrocardiogram at rest and used as an index of autonomic nerve function. The time constant (tau) and steady state level of the kinetic response for oxygen uptake (VO2) and heart rate (HR) were calculated using a mono-exponential model under constant- load exercise. RESULTS: 1) CVR-R andVO2max were significantly lower in the diabetic patients than in the healthy controls. Tau HR and tauVO2 were significantly longer in the diabetic patients than in the healthy controls. 2) TauVO2 and tau HR were significantly positively correlated in both groups, whereas CVR-R and tau HR, and tauVO2 were significantly negatively correlated in both groups. 3)VO2max and tau HR, and tauVO2 were significantly negatively correlated only in the healthy controls. CONCLUSIONS: These results suggest that CVR-R may reflect the characteristics of cardiovascular responses to exercise. However, though some previous studies have postulated that these characteristics of cardiovascular responses to exercise reflect cardiorespiratory endurance in healthy controls, our study confirmed no such correlation in diabetic patients