BMI, fat free mass, irisin levels drop after high altitude climbing
Body mass, body mass index (BMI), irisin, 25-hydroxyvitamin D (25(OH)D) levels and fat free mass decrease significantly after hypobaric hypoxia from high-altitude climbing, a new study shows.
On the other hand, hypobaric hypoxia increases myoglobin, interleukin (IL)-6, osteoprotegerin (OPG) and high-sensitivity C-reactive protein (hsCRP) levels.
A total of eight males (mean age 27±2.8 years) who underwent a 2-week climbing expedition in the Alps were subjected to body composition measurements. Concentrations of hsCRP, myoglobin, irisin, 25(OH)D, OPG and other biomarkers were measured from collected blood samples.
Body mass (72.3±6.05 vs 70.7±5.18 kg), BMI (22.7±1.27 vs 22.2±0.83 kg/m2) and fat-free mass (84.2±2.36 vs 84.1±2.78 percent) decreased significantly from baseline following 2 weeks of hypobaric hypoxia (p<0.05 for all). Similarly, levels of 25(OH)D and irisin decreased significantly from baseline (p<0.05 for both).
On the other hand, concentrations of OPG, IL-6, hsCRP and myoglobin significantly increased compared with baseline values (p<0.05 for all).
Lean body mass was significantly positively associated with irisin levels at baseline (p=0.0009) and after the expedition (p=0.0366). Similarly, hsCRP was positively associated with OPG (p=0.0465) and with the ratio between OPG and high sensitivity soluble receptor activator of NF-κB ligand (sRANKL; p=0.0102) after the expedition.
Significant positive correlations were also found between IL-6 and myostatin (p=0.028), irisin and 25(OH)D (p=0.0366), hsCRP concentrations and OPG/sRANKL ratio (p=0.0009), and myostatin levels and OPG/sRANKL ratio (p=0.0065).
According to the investigators, these results suggest that certain myokines may play a role in skeletal muscle regeneration and energy processes following hypobaric hypoxia exposure.