Objective:To explore the relationship among maximal oxygen uptake (VO 2max), heart rate recovery after exercise (HRR) and anti-G ability of fighter pilots. Methods:A total of 90 fighter pilots were selected by cluster sampling method, and the +G z tolerance that devoted by anti-G staining manoeuvre performing was predicted by anti-G and anti-hypoxia ability detector and G tolerance empirical formula. The values of VO 2max and HRR were collected under 25 W/min power increasing rate scheme. According to the level of VO 2max, pilots were divided into 3 groups: low level (the bottom third), intermediate level (the middle third) and high level (the top third). The differences of HRR value and +G z tolerance increment among the first, second and third minutes after exercise were compared among the pilots of different level of VO 2max. The correlation among the values of HRR, VO 2max and +G z tolerance increment were analyzed. Results:There were significant differences in the values of HRR and +G z tolerance increment at the second and the third minutes of exercise among the pilots with different VO 2max levels in 3 groups ( F=7.65, 10.64, 10.28, all P≤0.001). There was no obvious correlation between the values of HRR, VO 2max and +G z tolerance increment at the first minute after exercise ( r=0.020, -0.017, P=0.852, 0.871). The value of HRR at the second minute after exercise was positively correlated with VO 2max ( r=0.288, P=0.006), but not obviously with the +G z tolerance increment ( r=-0.017, P=0.150). The value of HRR value at the third minute was positively correlated with the increase of VO 2max and +G z tolerance increment ( r=0.433, 0.240, P<0.001, =0.023). VO 2max was positively correlated with the increase of +G z tolerance increment ( r=0.436, P<0.001). Conclusions:The increase of pilots′ VO 2max is conducive to the improvement of anti-G ability. The value of HRR at the third minute after exercise can be used as a sensitive monitoring index to predict pilot′s G-tolerance.

Objective:To explore the relationship among maximal oxygen uptake (VO 2max), heart rate recovery after exercise (HRR) and anti-G ability of fighter pilots. Methods:A total of 90 fighter pilots were selected by cluster sampling method, and the +G z tolerance that devoted by anti-G staining manoeuvre performing was predicted by anti-G and anti-hypoxia ability detector and G tolerance empirical formula. The values of VO 2max and HRR were collected under 25 W/min power increasing rate scheme. According to the level of VO 2max, pilots were divided into 3 groups: low level (the bottom third), intermediate level (the middle third) and high level (the top third). The differences of HRR value and +G z tolerance increment among the first, second and third minutes after exercise were compared among the pilots of different level of VO 2max. The correlation among the values of HRR, VO 2max and +G z tolerance increment were analyzed. Results:There were significant differences in the values of HRR and +G z tolerance increment at the second and the third minutes of exercise among the pilots with different VO 2max levels in 3 groups ( F=7.65, 10.64, 10.28, all P≤0.001). There was no obvious correlation between the values of HRR, VO 2max and +G z tolerance increment at the first minute after exercise ( r=0.020, -0.017, P=0.852, 0.871). The value of HRR at the second minute after exercise was positively correlated with VO 2max ( r=0.288, P=0.006), but not obviously with the +G z tolerance increment ( r=-0.017, P=0.150). The value of HRR value at the third minute was positively correlated with the increase of VO 2max and +G z tolerance increment ( r=0.433, 0.240, P<0.001, =0.023). VO 2max was positively correlated with the increase of +G z tolerance increment ( r=0.436, P<0.001). Conclusions:The increase of pilots′ VO 2max is conducive to the improvement of anti-G ability. The value of HRR at the third minute after exercise can be used as a sensitive monitoring index to predict pilot′s G-tolerance.

Objective To explore the imaging findings and diagnostic values of X-ray, CT, MR,and ultrasonography in traumatic knee joints hemarthrosis and lipohemarthrosis. Methods Traumatic knee joints hemarthrosis (12 knees) and lipohemarthrosis (18 knees) proved by operation (27 knees) or puncturation (3 knees) were included in the study. Horizontal-beam plain radiographs (16 knees), CT (30 knees), MRI (30 knees) and ultrasonography (24 knees) in supine position were investigated. Results (1)supine position horizontal-beam plain radiographs: Fat-liquid layer was found in 8 cases of lipohemarthrosis. Dense supragenual bursa was found in 1 case of lipohemarthrosis and 7 cases of hemarthrosis. Fracture (13 knees) was diagnosed correctly. (2) CT findings: double fluid-fluid layer was found in 11 of all 18 cases, and single fluid-fluid layer was found in 7 of 11 cases of lipohemarthrosis. Single fluid-fluid layer was found in 3 of 12 cases of hemarthrosis. Isodensity was detected in 9 cases, and high-density blood clot was found in 4 cases. Fracture (30 knees) was diagnosed correctly. (3) MRI findings: in 12 of 18 cases of lipohemarthrosis, double fluid-fluid layer was shown including supernatant layer as short T1, long T2signal and low signal after fat-suppression, middle layer as long T1, long T2 signal and high signal after fat-suppression, and dependent layer as iso-T1, iso-T2 and slight high signal after fat-suppression. Single fluid-fluid layer was seen in 6 cases, only had aforementioned upper and under layer.Only aforementioned supernatant layer and dependent layer were seen in 12 cases of hemarthrosis. 4 cases showed entire blood clot in fluid, T1WI showed middle signal or center iso-signal accompanied with peripheral high signal ring, and fat-suppression imaging showed high signal. T2WI and fat-suppressionimaging showed middling or high signal accompanied with peripheral low signal ring. Fracture (30 knees) was diagnosed correctly. (4) Ultrasound findings: In 10 of 14 cases of lipohemarthrosis, double fluid-fluid level was shown, supernatant layer as equal echo, middle layer as echoless, and dependent layer as cloudy echo. Four cases with single fluid-fluid level only showed aforementioned upper and under layer. Three of 10 cases of hemarthrosis showed single fluid-fluid level, only showing aforementioned upper and under layer,and 7 cases showed cloudy echo and float. In 3 cases the fluid blood clot showed irregular shape low-equal echo bolus. No fracture hne was found. Conclusions CT can clearly detect fracture line, hemarthrosis and lipohemarthresis, and can substitute plain radiography. MRI is the best way to diagnose hemarthresis and lipohemarthrosis. Ultrasonography can be used in diagnosing hemarthresis and lipohemarthrosis but not helpful in the diagnosis of fracture.

Objective: To observe the effect of simvastatin on osteoblastic cell differentiation of bone marrow stromal cells in vitro, and to elucidate the mechanisms of anabolic effect of simvastatin on bone formation. Methods: Bone marrow stromal cells from femur and tibia of adult female BALB C mice were cultured in vitro , after being treated with different concentrations of simvastatin for 72 h, changes of mRNA level of osteocalcin (OCN) were detected by RT PCR, change of OCN, and osteopontin (OPN) expression were examined by Western blot, and the changes of cellular alkaline phosphatase activity (ALP) were examined by histochemistry and enzymologic measurement. Results: After bone marrow stromal cells were treated with different concentration of simvastatin for 72 h, level of OCN mRNA increased, and expression of OCN and OPN also increased in a concentration dependent manner, and cellular ALP activity significantly increased in a concentration dependent manner. Conclusion: Simvastatin can stimulate osteoblastic differentiation,and improve cellular ALPase activity with high expression of osteocalcin and osteopontin in vitro. These may be parts of the mechanism of anabolic effect of simvastatin on bone formation.