{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,29]],"date-time":"2026-09-29T16:04:02Z","timestamp":1790697842392,"version":"4.1.0"},"reference-count":24,"publisher":"Human Kinetics","issue":"10","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2026,10,1]]},"abstract":"\n \n Purpose<\/jats:italic>\n <\/jats:bold>\n :<\/jats:italic>\n Increased total hemoglobin (Hb) mass is a physiological adaptation to altitude training; however, considerable individual differences have been observed in this response. This study aimed to determine the relationship between changes in total Hb mass (Hb\n mass<\/jats:sub>\n ) and conditioning indices during altitude training at an elevation of 1700\u00a0m.\n \n Methods<\/jats:italic>\n <\/jats:bold>\n :<\/jats:italic>\n Sixteen male long-distance runners participated in an altitude training camp at 1700\u00a0m for 9 to 23 days. The Hb\n mass<\/jats:sub>\n was determined using a carbon monoxide rebreathing method. Daily conditioning indices, including arterial oxygen saturation (SpO\n 2<\/jats:sub>\n ), heart rate (HR), SpO\n 2<\/jats:sub>\n \/HR ratio, subjective ratings of fatigue, sleep depth, training intensity, sleep duration, and daily running distance, were measured or recorded each morning.\n \n Results<\/jats:italic>\n <\/jats:bold>\n :<\/jats:italic>\n Hb\n mass<\/jats:sub>\n increased by 1.4% (1.9%) on average, with individual changes ranging from \u22122.1% to 4.6% (\u221218 to 35\u00a0g). A significant positive correlation was observed between \u0394Hb\n mass<\/jats:sub>\n and duration of stay at altitude (\n r<\/jats:italic>\n \u2009=\u2009.695,\n P<\/jats:italic>\n \u2009=\u2009.003). In the multiple regression analysis, duration of stay (\n B<\/jats:italic>\n \u2009=\u2009.235,\n P<\/jats:italic>\n \u2009=\u2009.001) and the SpO\n 2<\/jats:sub>\n \/HR ratio (\n B<\/jats:italic>\n \u2009=\u2009\u22124.462,\n P<\/jats:italic>\n \u2009=\u2009.001) were identified as significant predictors of Hb\n mass<\/jats:sub>\n change (\n R<\/jats:italic>\n 2<\/jats:sup>\n \u2009=\u2009.819).\n \n Conclusion<\/jats:italic>\n <\/jats:bold>\n :<\/jats:italic>\n These findings suggest that increases in Hb\n mass<\/jats:sub>\n may occur even at an altitude of 1700\u00a0m when sufficient exposure duration is ensured. Furthermore, the SpO\n 2<\/jats:sub>\n \/HR ratio may serve as a practical indicator reflecting individual physiological responses during altitude training.\n <\/jats:p>","DOI":"10.1123\/ijspp.2025-0672","type":"journal-article","created":{"date-parts":[[2026,8,6]],"date-time":"2026-08-06T17:59:03Z","timestamp":1786039143000},"page":"1143-1148","source":"Crossref","is-referenced-by-count":0,"title":["Changes in Total Hemoglobin Mass and Its Relationship With Conditioning Indices During Altitude Training at 1700\u2009m"],"prefix":"10.1123","volume":"21","author":[{"ORCID":"https:\/\/orcid.org\/0009-0006-9451-6156","authenticated-orcid":true,"given":"Michitaka","family":"Hirayama","sequence":"first","affiliation":[{"name":"Gifu Sports Association, Ontake Nigorigo High Altitude Training Center, Gero, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0002-1536-5080","authenticated-orcid":true,"given":"Akiko","family":"Matsuda","sequence":"additional","affiliation":[{"name":"TOENEC Co., Ltd., Nagoya, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0004-9329-9933","authenticated-orcid":true,"given":"Kazuhiro","family":"Sakamoto","sequence":"additional","affiliation":[{"name":"Department of Sport, Biwako Seikei Sport College, Otsu, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2892-5262","authenticated-orcid":true,"given":"Mitsuo","family":"Neya","sequence":"additional","affiliation":[{"name":"Department of Sport, Biwako Seikei Sport College, Otsu, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"100","reference":[{"issue":"10","key":"r1","series-title":"J Appl Physiol","doi-asserted-by":"publisher","first-page":"1194","DOI":"10.1152\/japplphysiol.01121.2014","article-title":"Hemoglobin mass and intravascular volume kinetics during and after exposure to 3,454-m altitude","volume":"119","author":"Siebenmann C","year":"2015","unstructured":"Siebenmann C, Cathomen A, Hug M, et al. 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