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Effect of arterial oxygenation on quadriceps fatigability during isolated muscle exercise.

Katayama K, Amann M, Pegelow DF, Jacques AJ, Dempsey JA

American journal of physiology. Regulatory, integrative and comparative physiology 292 巻 ( 3 ) 頁： R1279-86 2007年3月

Intermittent hypoxia does not increase exercise ventilation at simulated moderate altitude. 査読有り

Katayama, K., K. Sato, N. Hotta, K. Ishida, K. Iwasaki, and M. Miyamura.

Int. J. Sports Med. 28 巻頁： 480-487 2007年

記述言語：英語掲載種別：研究論文（学術雑誌）

Recent human studies have shown that resting hypoxic ventilatory response (HVR), which is an index of ventilatory chemosensitivity to hypoxia, increased after short-term intermittent hypoxia at rest. In addition, intermittent hypoxia leads to increases in ventilation and arterial oxygen saturation (SaO (2)) during exercise at simulated high altitude, with the increase in ventilation correlated to the change in HVR. However, no study has been made to clarify the relationship between ventilatory chemosensitivity and the exercise ventilation at moderate altitude following intermittent hypoxia during a resting state. The purpose of the present study, therefore, was to elucidate whether intermittent hypoxia at rest induces the increase in ventilation during exercise at moderate altitude that is accompanied by an increase in hypoxic chemosensitivity. Eighteen trained male runners were assigned to three groups, i.e., the first hypoxic group (H-1 group, n = 6), the second hypoxic group (H-2 group, n = 6), and a control group (C group, n = 6). The hypoxic tent system was utilized for intermittent hypoxia, and the oxygen levels in the tent were maintained at 15.5 +/- 0.1 % (simulated 2500 m altitude) for the H-1 group and 12.3 +/- 0.2 % (simulated 4300 m altitude) for the H-2 group. The H-1 and H-2 groups spent 1 hour per day in the hypoxic tent for 1 week. Maximal and submaximal exercise tests while breathing 15.5 +/- 0.01 % O (2) (simulated altitude of 2500 m) were performed before and after intermittent hypoxia. Resting HVR was also determined in each subject using a progressive isocapnic hypoxic method. In the H-2 group, HVR increased significantly (p < 0.05) following intermittent hypoxia, while no change in HVR was found in the H-1 or C group. Neither ventilation nor SaO (2) during maximal and submaximal exercise at a simulated altitude of 2500 m were changed in either group after 1 hour per day for 1 week of intermittent hypoxia. These results suggest that the change i

Chronic intermittent hypoxia increases the CO2 reserve in sleeping dogs. 査読有り

Katayama, K., C. A. Smith, K. S. Henderson, and J. A. Dempsey.

J. Appl. Physiol. 103 巻頁： 1973-1978 2007年

*The effect of arterial oxygenation on quadriceps fatigability during isolated muscle exercise. 査読有り

Katayama, K., M. Amann, D. F. Pagelow, A. J. Jacques, and J. A. Dempsey.

Am. J. Physiol. Regul. Integr. Physiol. 292 巻頁： R1279-R1286 2007年

記述言語：英語掲載種別：研究論文（学術雑誌）

The effect of various levels of oxygenation on quadriceps muscle fatigability during isolated muscle exercise was assessed in six male subjects. Twitch force (Qtw) was assessed using supra-maximal magnetic femoral nerve stimulation. In Experiment I, maximal voluntary contraction (MVC) and Qtw of resting quadriceps muscle were measured in nomoxia [arterial O2 saturation (SpO2) = 98.4; NORM], acute-hypoxia (SpO2 = 74.6%; HYPO), and acute-hyperoxia (SpO2 = 100%; HYPER). No significant differences were found for MVC and Qtw among the three FIO2s. In Experiment II, the subjects performed three sets of nine, intermittent, isometric, unilateral, submaximal quadriceps contractions (62% MVC) while breathing each FIO2. Qtw was assessed before and after exercise, and myoelectrical activity of the vastus lateralis was obtained during exercise. The percent reduction of twitch force (potentiated Qtw) in HYPO (-27.0%) was significantly (P<0.05) greater than those in NORM (-21.4%) and HYPER (-19.9%). The increase in integrated electromyogram over the course of the nine contractions in HYPO (15.4%) was higher (P<0.05) than in NORM (7.2%) or HYPER (6.7%). These results demonstrate that quadriceps muscle fatigability during isolated muscle exercise is exacerbated in acute hypoxia, and these effects were independent of the relative exercise intensity.

Comments on Point:Counterpoint "Positive effects of intermittent hypoxia (live high:train low) on exercise performance are/are not mediated primarily by augmented red cell volume".

Katayama K

Journal of applied physiology (Bethesda, Md. : 1985) 99 巻 ( 6 ) 頁： 2460 2005年12月

Intensive cycle training with artificial gravity maintains muscle size during bed rest.

Akima H, Katayama K, Sato K, Ishida K, Masuda K, Takada H, Watanabe Y, Iwase S

Aviation, space, and environmental medicine 76 巻 ( 10 ) 頁： 923-9 2005年10月

Changes In Ventilatory Responses To Hypercapnia And Hypoxia After Intermittent Hypoxia In Trained Athletes

Katayama Keisho, Sato Kohei, Matsuo Hiroshi, Hotta Norio, Sun Zhihu, Ishida Koji, Iwasaki Ken-ichi, Miyamura Miharu

MEDICINE AND SCIENCE IN SPORTS AND EXERCISE 37 巻頁： S294-S294 2005年5月

Changes in ventilatory responses to hypercapnia and hypoxia after intermittent hypoxia in humans

Katayama K, Sato K, Matsuo H, Hotta N, Sun ZH, Ishida K, Iwasaki K, Miyamura M

RESPIRATORY PHYSIOLOGY & NEUROBIOLOGY 146 巻 ( 1 ) 頁： 55-65 2005年3月

Vestibulo-cardiorespiratory responses at the onset of chair rotation in endurance runners.

Sato K, Katayama K, Katayama N, Hotta N, Ishida K, Miyamura M

The Japanese journal of physiology 55 巻 ( 1 ) 頁： 11-8 2005年2月

Effect of a repeated series of intermittent hypoxic exposures on ventilatory response in humans. 査読有り

Katayama, K.,H. Fujita, K. Sato, K. Ishida, K. Iwasaki, and M. Miyamura.

High Alt. Med. Biol. 6 巻頁： 50-59 2005年

*Changes in ventilatory responses to hypercapnia and hypoxia after intermittent hypoxia in humans. 査読有り

Katayama, K.,K. Sato, H. Matsuo, N. Hotta, Z. Sun, K. Ishida, K. Iwasaki, and M. Miyamura.

Respir. Physiol. Neurobiol. 146 巻頁： 55-65 2005年

記述言語：英語掲載種別：研究論文（学術雑誌）

The purpose of this study was to clarify the changes in hypercapnic and hypoxic ventilatory responses (HCVR and HVR) after intermittent hypoxia and following the cessation of hypoxic exposure. Twenty-nine males were assigned to one of four groups, i.e., a hypoxic (EX1-H, n=7) or a control (EX1-C, n=7) group in Experiment 1, and a hypoxic (EX2-H, n=8) or a control (EX2-C, n=7) group in Experiment 2. In each experiment, the hypoxic tent system was utilized for intermittent hypoxia, and the oxygen levels in the tent were maintained at 12.3+/-0.2%. In Experiment 1, the EX1-H group spent 3 h/day in the hypoxic tent for 1 week. HCVR and HVR were determined before and after 1 week of intermittent hypoxia, and again 1 and 2 week after the cessation of hypoxic exposure. In Experiment 2, the subjects in the EX2-H group performed 3 h/day for 2 weeks in intermittent hypoxia. HCVR and HVR tests were carried out before and after intermittent hypoxia, and were repeated again after 2 weeks of the cessation of hypoxic exposure. The slope of the HCVR in the EX1-H group did not show a significant increase after 1 week of intermittent hypoxia, while HCVR in the EX2-H group increased significantly after 2 weeks of intermittent hypoxia. The HCVR intercept was unchanged following 1 or 2 weeks of intermittent hypoxia. There was a significant increase in the slope of the HVR after 1 and 2 weeks of intermittent hypoxia. The increased HCVR and HVR returned to pre-hypoxic levels after 2 weeks of the cessation of hypoxia. These results suggest that 3 h/day for 2 weeks of intermittent hypoxia leads to an increase in central hypercapnic ventilatory chemosensitivity, which is not accompanied by a re-setting of the central chemoreceptors, and that the increased hypercapnic and hypoxic chemosensitivities are restored within 2 weeks after the cessation of hypoxia.

Acceleration with exercise during head-down bed rest preserves upright exercise responses.

Katayama K, Sato K, Akima H, Ishida K, Takada H, Watanabe Y, Iwase M, Miyamura M, Iwase S

Aviation, space, and environmental medicine 75 巻 ( 12 ) 頁： 1029-35 2004年12月

Ventilatory and heart rate responses at the onset of chair rotation in man.

Miyamura M, Ishida K, Katayama K, Shima N, Matsuo H, Sato K

The Japanese journal of physiology 54 巻 ( 5 ) 頁： 499-503 2004年10月

Effect of centrifuge-induced artificial gravity and ergometric exercise on cardiovascular deconditioning, myatrophy, and osteoporosis induced by a -6 degrees head-down bedrest.

Iwase S, Takada H, Watanabe Y, Ishida K, Akima H, Katayama K, Iwase M, Hirayanagi K, Shiozawa T, Hamaoka T, Masuo Y, Custaud MA

Journal of gravitational physiology : a journal of the International Society for Gravitational Physiology 11 巻 ( 2 ) 頁： P243-4 2004年7月

Effect of intermittent hypoxia on oxygen uptake during submaximal exercise in endurance athletes.

Katayama K, Sato K, Matsuo H, Ishida K, Iwasaki K, Miyamura M

European journal of applied physiology 92 巻 ( 1-2 ) 頁： 75-83 2004年6月

Ventilatory and circulatory responses at the onset of voluntary exercise and passive movement in sprinters.

Sato K, Matsuo H, Katayama K, Ishida K, Honda Y, Katsumata K, Miyamura M

European journal of applied physiology 92 巻 ( 1-2 ) 頁： 196-203 2004年6月

Ventilatory and cardiovascular responses to hypercapnia after 20 days of head-down bed rest. 査読有り

Katayama K, Sato K, Akima H, Ishida K, Yanagiya T, Kanehisa H, Fukuoka H, Fukunaga T, Miyamura M

Aviation, space, and environmental medicine 75 巻 ( 4 ) 頁： 312 - 6 2004年4月

Effects of 20 days head-down bed rest on ventilatory and cardiovascular responses to hypercapnia. 査読有り

Katayama, K., K. Sato, H. Akima, K. Ishida, T. Yanagiya, H. Kanehisa, H. Fukuoka, T. Fukunaga, and M. Miyamura.

Aviat. Space Environ. Med. 75 巻頁： 312-316 2004年

Effect of intermittent hypoxia on oxygen uptake during submaximal exercise in endurance athletes. 査読有り

Katayama, K., K. Sato, H. Matsuo, K. Ishida, K. Iwasaki, and M. Miyamura.

Eur. J. Appl. Physiol. 92 巻頁： 75-83 2004年

Effects of intermittent hypoxic training and detraining on ventilatory chemosensitive adaptations in endurance athletes. 査読有り

Katayama, K., K. Sato, H. Matsuo, K. Ishida, S. Mori, and M. Miyamura.

Adv. Exp. Med. Biol. 551 巻頁： 299-304 2004年

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