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Morphologic and Metabolic Response to Chronic Hypoxia: the Muscle System

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Abstract

The sections in this article are:

1 Human Muscular Performance at Altitude: Historical Aspects
1.1 Physiology
1.2 Biochemistry
2 Acute Vs. Chronic Exposure: Effects of Altitude and Exposure Time
2.1 Acute Exposure
2.2 Chronic Hypoxia
2.3 High‐Altitude Natives vs. Acclimatized Lowlanders
3 Comparing Animal and Human Data
4 Structural and Metabolic Characteristics of High‐Altitude Natives
4.1 Body Composition
4.2 Muscle Structure and Metabolic Markers
5 Structural and Physiological Adaptations to Chronic Hypoxia
5.1 Changes of Body and Muscle Mass and Nutrition
5.2 Limiting Factors to Aerobic and Anaerobic Exercise
6 Morphological Changes of Skeletal Muscle Tissue
6.1 Fiber Size and Fiber Type Distribution
6.2 Capillary Supply
6.3 Mitochondria
6.4 Fiber Damage and Regenerative Events
7 Training and Muscle Adaptations with Hypoxia
7.1 Altitude Training
7.2 Training in Normobaric Hypoxia
Figure 1. Figure 1.

Maximum O2 consumption (; percentage of the sea‐level value made equal to 100) as a function of altitude (km) after acute (a, less than 5 days) and chronic (b, more than 3 wk) exposure. Each symbol represents data from a different reference as follows: a: ŝ, 128; •, 3; ▽, 55; ▾, 81; □, 54; ▪, 36; △, 89; ▴, 65; ⋄, 170; ♦, 53; , 34; *, 46; , 96; , 74b. b: ◯, 154; •, 38; ▽, 5; ▾, 4; □, 34; ▪, 192; △, 179; ▴, 74b; ⋄, 64; ♦, 34; , 96.

Figure 2. Figure 2.

as a function of time before exposure, in the course of altitude exposure, and following return to sea level (solid symbols, altitude data; open symbols, sea‐level measurement; mean of 10 subjects ± S.D.) .

Figure 3. Figure 3.

Blood hemoglobin saturation (SaO2, %) at rest and during exercise at sea level and at 5,050 m in a sedentary (FC) and an athletic (BK) subject .

Figure 4. Figure 4.

Micrograph of cross‐section of portions of muscle fibers in a muscle biopsy of M. vastus lateralis as used for morphometry of capillarity and fiber size (arrows indicate capillaries).

Figure 5. Figure 5.

Relative changes of body mass (Mb), maximal oxygen uptake capacity (, measured in normoxia after continuous and in hypoxia after discontinuous exposure to severe hypoxia), muscle cross‐sectional area [ā(m)], capillary density [NA(c,f)], capillary to fiber ratio [NN(c,f)], total capillary length [J(c)], mitochondrial volume density [Vv(mt,f)], and total mitochondrial volume [V(mt)] with continous (a) and discontinuous (b) exposure to hypoxia. (From Hoppeler and Desplanches, 1992.)

Figure 6. Figure 6.

Micrograph of a section of muscle tissue of a subject after exposure to chronic hypoxia. Accumulation of the degradation pigment lipofuscin (lf) close to the muscle fiber nucleus (N) can be seen (li, lipid droplet; mf, myofibrils; mi, mitochondria).

Figure 7. Figure 7.

Micrograph of a satellite cell (Sat) located under the basement membrane in close apposition to muscle fiber (N, nucleus of satellite cell; mf, myofibrils in muscle fiber).



Figure 1.

Maximum O2 consumption (; percentage of the sea‐level value made equal to 100) as a function of altitude (km) after acute (a, less than 5 days) and chronic (b, more than 3 wk) exposure. Each symbol represents data from a different reference as follows: a: ŝ, 128; •, 3; ▽, 55; ▾, 81; □, 54; ▪, 36; △, 89; ▴, 65; ⋄, 170; ♦, 53; , 34; *, 46; , 96; , 74b. b: ◯, 154; •, 38; ▽, 5; ▾, 4; □, 34; ▪, 192; △, 179; ▴, 74b; ⋄, 64; ♦, 34; , 96.



Figure 2.

as a function of time before exposure, in the course of altitude exposure, and following return to sea level (solid symbols, altitude data; open symbols, sea‐level measurement; mean of 10 subjects ± S.D.) .



Figure 3.

Blood hemoglobin saturation (SaO2, %) at rest and during exercise at sea level and at 5,050 m in a sedentary (FC) and an athletic (BK) subject .



Figure 4.

Micrograph of cross‐section of portions of muscle fibers in a muscle biopsy of M. vastus lateralis as used for morphometry of capillarity and fiber size (arrows indicate capillaries).



Figure 5.

Relative changes of body mass (Mb), maximal oxygen uptake capacity (, measured in normoxia after continuous and in hypoxia after discontinuous exposure to severe hypoxia), muscle cross‐sectional area [ā(m)], capillary density [NA(c,f)], capillary to fiber ratio [NN(c,f)], total capillary length [J(c)], mitochondrial volume density [Vv(mt,f)], and total mitochondrial volume [V(mt)] with continous (a) and discontinuous (b) exposure to hypoxia. (From Hoppeler and Desplanches, 1992.)



Figure 6.

Micrograph of a section of muscle tissue of a subject after exposure to chronic hypoxia. Accumulation of the degradation pigment lipofuscin (lf) close to the muscle fiber nucleus (N) can be seen (li, lipid droplet; mf, myofibrils; mi, mitochondria).



Figure 7.

Micrograph of a satellite cell (Sat) located under the basement membrane in close apposition to muscle fiber (N, nucleus of satellite cell; mf, myofibrils in muscle fiber).

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P. Cerretelli, H. Hoppeler. Morphologic and Metabolic Response to Chronic Hypoxia: the Muscle System. Compr Physiol 2011, Supplement 14: Handbook of Physiology, Environmental Physiology: 1155-1181. First published in print 1996. doi: 10.1002/cphy.cp040250