Transferability of Exercise Intensity Based on Muscle Oxygenation from Normoxia to Hypoxia in Ski-Mountaineering Athletes—Exploratory Study
Frequent changes in altitude and oxygen levels limit the practical application of traditionally derived exercise thresholds or training zones based on heart rate (HR) or blood lactate concentration (bLa). We investigated the transferability of a muscle oxygenation (SmO<sub>2</sub>)-based...
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2024-12-01
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| author | Kinga Rębiś Tomasz Kowalski Kamil Michalik Andrzej Klusiewicz |
| author_facet | Kinga Rębiś Tomasz Kowalski Kamil Michalik Andrzej Klusiewicz |
| author_sort | Kinga Rębiś |
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| description | Frequent changes in altitude and oxygen levels limit the practical application of traditionally derived exercise thresholds or training zones based on heart rate (HR) or blood lactate concentration (bLa). We investigated the transferability of a muscle oxygenation (SmO<sub>2</sub>)-based intensity prescription between different hypoxic conditions to assess the suitability of real-time SmO<sub>2</sub> measurements for ski-mountaineering (SKIMO) athletes during submaximal endurance exercise. A group of 15 well-trained male SKIMO athletes performed a graded-intensity run test in normoxia (87 m ASL, FiO<sub>2</sub> = 20.8%) to determine the anaerobic threshold (AnT) with the mod-Dmax method, and maximal lactate steady state (MLSS) assessments in acute normobaric hypoxia (3000 m ASL, FiO<sub>2</sub> = 14.4%) with the intensity aligned to 90–105% of SmO<sub>2</sub> at the normoxia-determined AnT. SmO<sub>2</sub>, HR, and bLa were monitored during both tests. The number of MLSS assessments without a bLa increase over 1 mmol·L<sup>−1</sup> was reported. Paired <i>t</i>-tests with Cohen’s d effect sizes and intraclass correlation coefficient (ICC) were computed to compare the bLa and HR at the AnT in normoxia and MLSS averages in hypoxia, as both corresponded to equivalent SmO<sub>2</sub>. Out of the 15 MLSS assessments, 11 (73.3%) were performed without a bLa increase over 1 mmol·L<sup>−1</sup>. Significant differences at equivalent SmO<sub>2</sub> in normoxia and hypoxia were found for HR (175 ± 11.7 vs. 160 ± 14.2 bpm, <i>p</i> = 0.005, d = 1.02), but not for bLa (4.9 ± 1.2 vs. 5.1 ± 2.4 mmol·L<sup>−1</sup>, <i>p</i> = 0.845, d = −0.05). ICC(2,k) for HR and bLa were 0.56 (95% CI: −0.24, 0.85) and 0.40 (95% CI: −0.75, 0.80), respectively. The results indicate a fair transferability of a SmO<sub>2</sub>-based intensity prescription between different hypoxic conditions in well-trained SKIMO athletes during submaximal endurance exercise. The practical significance of the observations depends on the required accuracy of the exercise intensity determination. |
| format | Article |
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| institution | Kabale University |
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| spelling | doaj-art-373922f14b724129bfbdd1c075dd6f462024-12-27T14:54:36ZengMDPI AGSports2075-46632024-12-01121235110.3390/sports12120351Transferability of Exercise Intensity Based on Muscle Oxygenation from Normoxia to Hypoxia in Ski-Mountaineering Athletes—Exploratory StudyKinga Rębiś0Tomasz Kowalski1Kamil Michalik2Andrzej Klusiewicz3Department of Physiology, Institute of Sport—National Research Institute, 01-982 Warsaw, PolandDepartment of Physiology, Institute of Sport—National Research Institute, 01-982 Warsaw, PolandFaculty of Physical Education and Sport, Wroclaw University of Health and Sport Sciences, 51-612 Wroclaw, PolandDepartment of Physical Education and Health in Biala Podlaska, Faculty in Biała Podlaska, Jozef Pilsudski University of Physical Education, 00-968 Warsaw, PolandFrequent changes in altitude and oxygen levels limit the practical application of traditionally derived exercise thresholds or training zones based on heart rate (HR) or blood lactate concentration (bLa). We investigated the transferability of a muscle oxygenation (SmO<sub>2</sub>)-based intensity prescription between different hypoxic conditions to assess the suitability of real-time SmO<sub>2</sub> measurements for ski-mountaineering (SKIMO) athletes during submaximal endurance exercise. A group of 15 well-trained male SKIMO athletes performed a graded-intensity run test in normoxia (87 m ASL, FiO<sub>2</sub> = 20.8%) to determine the anaerobic threshold (AnT) with the mod-Dmax method, and maximal lactate steady state (MLSS) assessments in acute normobaric hypoxia (3000 m ASL, FiO<sub>2</sub> = 14.4%) with the intensity aligned to 90–105% of SmO<sub>2</sub> at the normoxia-determined AnT. SmO<sub>2</sub>, HR, and bLa were monitored during both tests. The number of MLSS assessments without a bLa increase over 1 mmol·L<sup>−1</sup> was reported. Paired <i>t</i>-tests with Cohen’s d effect sizes and intraclass correlation coefficient (ICC) were computed to compare the bLa and HR at the AnT in normoxia and MLSS averages in hypoxia, as both corresponded to equivalent SmO<sub>2</sub>. Out of the 15 MLSS assessments, 11 (73.3%) were performed without a bLa increase over 1 mmol·L<sup>−1</sup>. Significant differences at equivalent SmO<sub>2</sub> in normoxia and hypoxia were found for HR (175 ± 11.7 vs. 160 ± 14.2 bpm, <i>p</i> = 0.005, d = 1.02), but not for bLa (4.9 ± 1.2 vs. 5.1 ± 2.4 mmol·L<sup>−1</sup>, <i>p</i> = 0.845, d = −0.05). ICC(2,k) for HR and bLa were 0.56 (95% CI: −0.24, 0.85) and 0.40 (95% CI: −0.75, 0.80), respectively. The results indicate a fair transferability of a SmO<sub>2</sub>-based intensity prescription between different hypoxic conditions in well-trained SKIMO athletes during submaximal endurance exercise. The practical significance of the observations depends on the required accuracy of the exercise intensity determination.https://www.mdpi.com/2075-4663/12/12/351near-infrared spectroscopyNIRShypoxiaexercise testinganaerobic thresholdSKIMO |
| spellingShingle | Kinga Rębiś Tomasz Kowalski Kamil Michalik Andrzej Klusiewicz Transferability of Exercise Intensity Based on Muscle Oxygenation from Normoxia to Hypoxia in Ski-Mountaineering Athletes—Exploratory Study Sports near-infrared spectroscopy NIRS hypoxia exercise testing anaerobic threshold SKIMO |
| title | Transferability of Exercise Intensity Based on Muscle Oxygenation from Normoxia to Hypoxia in Ski-Mountaineering Athletes—Exploratory Study |
| title_full | Transferability of Exercise Intensity Based on Muscle Oxygenation from Normoxia to Hypoxia in Ski-Mountaineering Athletes—Exploratory Study |
| title_fullStr | Transferability of Exercise Intensity Based on Muscle Oxygenation from Normoxia to Hypoxia in Ski-Mountaineering Athletes—Exploratory Study |
| title_full_unstemmed | Transferability of Exercise Intensity Based on Muscle Oxygenation from Normoxia to Hypoxia in Ski-Mountaineering Athletes—Exploratory Study |
| title_short | Transferability of Exercise Intensity Based on Muscle Oxygenation from Normoxia to Hypoxia in Ski-Mountaineering Athletes—Exploratory Study |
| title_sort | transferability of exercise intensity based on muscle oxygenation from normoxia to hypoxia in ski mountaineering athletes exploratory study |
| topic | near-infrared spectroscopy NIRS hypoxia exercise testing anaerobic threshold SKIMO |
| url | https://www.mdpi.com/2075-4663/12/12/351 |
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