High-altitude Tibetans undergo a pattern of adaptations to chronic hypoxia characterized, among others, by a more efficient aerobic performance compared with acclimatized lowlanders.To test whether such changes may persist upon descent to moderate altitude, oxygen uptake of 17 male Tibetan natives lifelong residents at 3500-4500 m was assessed within 1 month upon migration to 1300 m. Exercise protocols were: 5 min treadmill walking at 6 km h −1 on increasing inclines from +5 to +15% and 5 min running at 10 km h −1 on a +5% grade. The data (mean ± S.E.M.) were compared with those obtained on Nepali lowlanders. When walking on +10, +12.5 and +15% inclines, netV O 2 of Tibetans was 25.2 ± 0.7, 29.1 ± 1.1 and 31.3 ± 0.9 ml kg −1 min −1 , respectively, i.e. 8, 10 and 13% less (P < 0.05) than that of Nepali. At the end of the heaviest load, blood lactate concentration was lower in Tibetans than in Nepali (6.0 ± 0.9 versus 8.9 ± 0.6 mM; P < 0.05). During running,V O 2 of Tibetans was 35.1 ± 0.8 versus 39.3 ± 0.7 ml kg −1 min −1 (i.e. 11% less; P < 0.01). In conclusion, during submaximal walking and running at 1300 m, Tibetans are still characterized by lower aerobic energy expenditure than control subjects that is not accounted for by differences in mechanical power output and/or compensated for by anaerobic glycolysis. These findings indicate that chronic hypoxia induces metabolic adaptations whose underlying mechanisms still need to be elucidated, that persist for at least 1 month upon descent to moderate altitude. It has been long recognized that, with increasing altitude, acclimatized Caucasian lowlanders lose progressively greater fractions of their sea level maximal aerobic power (V O 2 peak ). By contrast, Tibetans, whose ancestors might have been living and thriving at altitudes between 3000 and 4500 m for more than 25 000 years (Dennell et al. 1988), are characterized by a peculiar pattern of adaptations to chronic hypoxia. In fact, compared with acclimatized lowlanders, Tibetan highlanders feature at peak exercise higher arterial O 2 saturation (S aO 2 ), higher aerobic power (V O 2 peak ) and heart rate (HR peak ), the values of the two latter variables being at altitude in the range of those found at sea level in age-, gender-and fitness-matched individuals (Sun et al. 1990;Niu et al. 1995;Zhuang et al. 1996;Chen et al. 1997). In addition, compared with acclimatized Han Chinese long-time residents of 4700 m, Tibetans performing an incremental cycle ergometer exercise are characterized by lower O 2 consumption for given submaximal exercise loads, i.e. a better economy of locomotion, and can develop greater peaks of mechanical power output despite lowerV O 2 peak levels (Ge et al. 1994). Interestingly, the same features were found at 3658 m in lifelong Tibetan residents of 4400 m compared with 3658 m (Curran et al. 1998). On the other hand, second generation Tibetan lowland natives born at 1300 m, never before exposed to high altitude, acclimatize to 5050 m more quickly than Caucasians and within 1 month reco...
Background: The burden of musculoskeletal trauma is increasing in low- and middle-income countries. Due to the low clinical follow-up rates in these regions, the Squat-and-Smile test (S&S) has previously been proposed as a proxy to assess bone healing (BH) capacity after surgery involving bone fractures. This study deals with various aspects of using S&S and bone radiography examination to obtain information about an individual's ability to recover after a trauma. In summary, we performed the S&S test to assess the possibility of recovering biomechanical function in lower limbs in a remote area of Kenya (Samburu County). Methods: Eighty-nine patients (17.9% F; 31.7 ± 18.9 yrs) who underwent intramedullary nail treatment for femur or tibia fractures were enrolled in this study. Both S&S [evaluated by a goal attainment scale (GAS)] and x-ray (evaluated by REBORNE, Bone Healing Score) were performed at 6 and 24 weeks, postoperatively. An acceptable margin for satisfactory S&S GAS scores was determined by assessing its validity, reliability, and sensitivity. Results: S&S GAS scores increased over time: 80.2% of patients performed a satisfactory S&S at the 24-weeks follow-up with a complete BH. A high correlation between S&S GAS and REBORNE at the 6- and 24- weeks’ timepoint was found. Facial expression correlated partially with BH. The S&S proved to be accurate at correctly depicting the BH process (75% area fell under the Receiver Operator Curve). Conclusion: The S&S provides a possible substitution for bone x-ray during BH assessment. The potential to remotely follow up the BH is certainly appealing in low- and middle-income countries, but also in high-income countries; as was recently observed with the Covid-19 pandemic when access to a hospital is not conceivable.
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