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

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

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

Physical Function and Health-Related Quality of Life after Surgery for Nontuberculous Mycobacterial Pulmonary Disease: A Prospective Cohort Study

Purpose: To investigate the exercise capacity and health-related quality of life (HRQOL) of surgical patients with nontuberculous mycobacterial pulmonary disease (NTM-PD) preoperatively versus 6 months postoperatively.Methods: This prospective observational study included patients with NTM-PD and was conducted at a single center. The intervention was surgical resection plus perioperative and post-discharge physical therapy. The physical function was assessed preoperatively and 6 months postoperatively using the 6-minute walk test (6MWT). HRQOL was assessed preoperatively and 6 months postoperatively using the Short-Form 36 (SF-36) health survey questionnaire and St. George’s Respiratory Questionnaire. The postoperative HRQOL was compared between patients with and without preoperative clinical symptoms.Results: In total, 35 patients were analyzed. The preoperatively symptomatic group had significantly lower preoperative HRQOL than the preoperatively asymptomatic group (p <0.05). Compared with preoperatively, there were significant improvements at 6 months postoperatively in the 6MWT (p <0.01) and HRQOL, mainly in the SF-36 mental component summary (p <0.01). The SF-36 mental component summary in the preoperatively symptomatic group was very significantly improved from preoperatively to 6 months postoperatively (p <0.05).Conclusion: The combination of surgical treatment and physical therapy for NTM-PD contributes to improvements in physical function and HRQOL

Vastus lateralis oxygenation during prolonged cycling in healthy males

This study examined the relationship between the acute cardiorespiratory and muscleoxygenation/blood volume changes during prolonged exercise. Eight healthy male volunteers (mean VO2max = 41.6 ± 2.4 ml/kg/min) performed 60 minutes submaximal cycling at 500f VO2max. Oxygen uptake (VO2) was measured by indirect spirometry, cardiac output (CO) was estimated via Portapres, and right vastus lateralis oxyhemoglobin/myoglobin (OxyHb/Mb), deoxyhemoglobin/myoglobin (DeoxyHb/Mb) and total hemoglobin/myoglobin (Total Hb/Mb) were recorded using near infrared spectroscopy. After 40 minutes of exercise, there was a significant increase in VO2 due to a significantly higher (a – v)O2diff. After 30 mins of exercise CO was unchanged, but there was a significant decrease in stroke volume and a proportionate increase in heart rate indicating the occurrence of cardiovascular drift. During the first few minutes of exercise, there was a decline in OxyHb/Mb and Total Hb/Mb while DeoxyHb/Mb remained unchanged. Thereafter OxyHb/Mb and Total Hb/Mb increased systematically until the termination of exercise while DeoxyHb/Mb declined. After 40 minutes of exercise, these changes were significantly different from the baselines values. There were no significant correlations between the changes in the NIRS variables and systemic VO2 or mixed (a – v)O2diff during exercise. These results suggest that factors other than localized changes in muscle oxygenation and blood volume account for the increased VO2 during prolonged submaximal exercise

Value of systematic intervention for chronic obstructive pulmonary disease in a regional Japanese city based on case detection rate and medical cost

Objective: We established a COPD taskforce for early detection, diagnosis, treatment, and intervention. We implemented a pilot intervention with a prospective and longitudinal design in a regional city. This study evaluates the usefulness of the COPD taskforce and intervention based on COPD case detection rate and per capita medical costs. Method: We distributed a questionnaire to all 8,878 inhabitants aged 50?89 years, resident in Matsuura, Nagasaki Prefecture in 2006. Potentially COPD-positive persons received a pulmonary function test and diagnosis. We implemented ongoing detection, examination, education, and treatment interventions, performed follow-up examinations or respiratory lessons yearly, and supported the health maintenance of each patient. We compared COPD medical costs in Matsuura and in the rest of Nagasaki Prefecture using data from 2004 to 2013 recorded by the association of Nagasaki National Health Insurance Organization, assessing 10-year means and annual change. Results: As of 2014, 256 people have received a definitive diagnosis of COPD; representing 31% of the estimated total number of COPD patients. Of the cases detected, 87.5% were mild or moderate in severity. COPD medical costs per patient in Matsuura were significantly lower than the rest of Nagasaki Prefecture, as was rate of increase in cost over time. Conclusion: The COPD program in Matsuura enabled early detection and treatment of COPD patients and helped to lower the associated burden of medical costs. The success of this program suggests that a similar program could reduce the economic and human costs of COPD morbidity throughout Japan

Incremental Shuttle Walk Distance as an Indicator for Functional Exercise Capacity of Pre-Surgical Patients with Nontuberculous Mycobacterial Lung Disease

The incidence of nontuberculous mycobacterial lung disease (NTMLD) is increasing worldwide, the number of lung surgeries is increasing accordingly. The disease is progressive and is characterized by exertional intolerance, respiratory dysfunctions, and impaired health-related quality of life (HRQOL). Treatment comprises multidrug antibiotic treatment combined with lung resection. The incremental shuttle walk distance (ISWD) is a standard tool for assessing the patients\u27 tolerance to lung resection. The exertional tolerance, physical functions and HRQOL among pre-surgical patients with NTMLD are clinically important, but not fully studied yet from the viewpoint of physiotherapy. The purpose of this study was to explore the clinical significance of ISWD for assessing the exercise capacity of pre-surgical patients with NTMLD. For peripheral muscle evaluation, the strength of the quadriceps femoris muscle was measured. HRQOL was evaluated using scores of the St. George\u27s Respiratory Questionnaire (SGRQ). Thirty-three patients (mean age 54.9 ± 13 years) were enrolled. The mean ISWD was 505 ± 134 m, shorter than the reference values (ISWD %predicted: 96 ± 27%). Regression analysis showed significant associations between ISWD and percent-predicted vital capacity (r = 0.38, p = 0.03) and percent quadriceps force/body weight (r = 0.54, p = 0.001). HRQOL assessed by SGRQ scores was correlated with ISWD (r < -0.4, p < 0.05). Multiple regression analysis showed that ISWD was significantly associated with leg muscle strength and with HRQOL. In conclusion, ISWD is useful to evaluate the exercise capacity among pre-surgical patients with NTML

The effect of muscle stiffness and muscle activity in the dorsolumbar region on Stretch Pole® exercise

本研究は,ストレッチポール®を使用したエクササイズによる腰背部筋での筋硬度,筋放電量の変化を明らかにすることを目的とした.対象は,腰痛を有しない若年成人15名(男性5名,女性10名,年齢22.5±1.5歳)とし,ストレッチポール®を使用したエクササイズの基本となるベーシックセブンを実施した.エクササイズの前後に,立位にて触覚センサーおよび表面筋電計を用いて第10胸椎(Th10)と第3腰椎(L3)レベルでの左右脊柱起立筋の筋硬度および筋放電量を測定した.その結果は,各レベルの左右別ではエクササイズにより筋硬度,筋放電量ともに有意な変化は認められなかったが,筋硬度の左右差の絶対値がTh10レベルにおいて有意に減少した(p<0.025).この結果より,ストレッチポール®エクササイズの基本となるベーシックセブン法はTh10の高さの脊柱起立筋の筋硬度の左右差に影響することが明らかとなった.The purpose of this study was to understand alterations of muscle stiffness and muscle activity in the dorsolumbar muscle quantitatively by exercising with a Stretch Pole®. The subjects were fifteen healthy adults (5 men and 10 women) who did not have low back pain. The Basic Seven exercise with the Stretch Pole® was applied as an exercise protocol. We measured the muscle stiffness and muscle activity of the bilateral elector spinae at the height of the tenth thoracic vertebra and third lumbar vertebra to make a comparison before and after exercise with the Stretch Pole® using a tactile sensor and surface electromyography on standing. The results of this study showed that there were no significant differences between muscle stiffness and muscle activity on each side of elector spinae at either height, when we made a comparison before and after exercise with the Stretch Pole®. However, there were significant differences of absolute right and left muscle stiffness in the elector spinae at the height of the tenth thoracic vertebra (p<0.025). It is suggested that right and left differences of muscle stiffness in the elector spinae at the height of the tenth thoracic vertebra were influenced by the Basic Seven which were the basis of exercise with the Stretch Pole®

Effect of a Chronic Obstructive Pulmonary Disease (COPD) Intervention on COPD Awareness in a Regional City in Japan

Objective: The purpose of this study was to examine the effect of an intervention for chronic obstructive pulmonary disease (COPD) on COPD awareness in a regional city in Japan.Methods Self-administered questionnaires were completed by the residents of the city of Matsuura, Japan. Residents (?50 years) of the mainland in Matsuura were included in a COPD intervention project (mainland group), while residents of the islands district received no intervention due to geographical issues (island group). The rates of COPD awareness and accuracy of responses to the questions about COPD were compared between the two groups.Materials: The study included 5,891 residents 40 to 74 years of age of Matsuura in 2013. The mainland group comprised 4,419 subjects, and the island group 1,472 included subjects.Results: The overall response rate to the questionnaire was 24.6%, with similar response rates between the two groups. The rate of COPD awareness in the mainland group was 24.5%, which was significantly higher than that observed in the island group (11.8%) (p<0.01). The rate of awareness tended to decrease in association with increasing age. Among 276 responders who stated they were aware of COPD, the accuracy rate for responses to the questions about COPD was not significantly different between the groups.Conclusion: In the present study, there was a difference in COPD awareness between the two groups, suggesting that COPD interventions may increase awareness of the disease. However, the level of knowledge regarding COPD remained low and modifications to the intervention are required to improve awareness of the condition, especially among elderly subjects