***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Abstract Hypoxia is an important modulator of endurance exercise‐induced oxidative adaptations in skeletal muscle . However , whether hypoxia affects resistance exercise‐induced muscle adaptations remains unknown . Here , we determined the effect of resistance exercise training under systemic hypoxia on muscular adaptations known to occur following both resistance and endurance exercise training , including muscle cross‐sectional area ( CSA ) , one‐repetition maximum ( 1RM ) , muscular endurance , and makers of mitochondrial biogenesis and angiogenesis , such as peroxisome proliferator‐activated receptor‐γ coactivator‐1α ( PGC‐1α ) , citrate synthase ( CS ) activity , nitric oxide synthase ( NOS ) , vascular endothelial growth factor ( VEGF ) , hypoxia‐inducible factor‐1 ( HIF‐1 ) , and capillary‐to‐fiber ratio . Sixteen healthy male subjects were r and omly assigned to either a normoxic resistance training group ( NRT , n = 7 ) or a hypoxic ( 14.4 % oxygen ) resistance training group ( HRT , n = 9 ) and performed 8 weeks of resistance training .  Blood and muscle biopsy sample s were obtained before and after training . After training muscle CSA of the femoral region , 1RM for bench‐press and leg‐press , muscular endurance , and skeletal muscle VEGF protein levels significantly increased in both groups . The increase in muscular endurance was significantly higher in the HRT  group . Plasma VEGF concentration and skeletal muscle capillary‐to‐fiber ratio were significantly higher in the HRT group than the NRT group following training . Our results suggest that , in addition to increases in muscle size and strength , HRT may also lead to increased muscular endurance and the promotion of angiogenesis in skeletal muscle To test the hypothesis that severe hypoxia during low-resistance/high-repetition strength training promotes muscle hypertrophy , 19 untrained males were assigned r and omly to 4 weeks of low-resistance/high-repetition knee extension exercise in either normoxia or in normobaric hypoxia ( FiO2 0.12 ) with recovery in normoxia . Before and after the training period , isokinetic strength tests were performed , muscle cross-sectional area ( MCSA ) measured ( magnetic resonance imaging ) and muscle biopsies taken . The significant increase in strength endurance capacity observed in both training groups was not matched by changes in MCSA , fibre type distribution or fibre cross-sectional area . RT-PCR revealed considerable inter-individual variations with no significant differences in the mRNA levels of hypoxia markers , glycolytic enzymes and myosin heavy chain isoforms . We found significant correlations , in the hypoxia group only , for those hypoxia marker and glycolytic enzyme mRNAs that have previously been linked to hypoxia-specific muscle adaptations . This is interpreted as a small , otherwise undetectable adaptation to the hypoxia training condition . In terms of strength parameters , there were , however , no indications that low-resistance/high-repetition training in severe hypoxia is superior to equivalent normoxic training This study was performed to explore changes in gene expression as a consequence of exercise training at two levels of intensity under normoxic and normobaric hypoxic conditions ( corresponding to an altitude of 3,850 m ) . Four groups of human subjects trained five times a week  for a total of 6 wk on a bicycle ergometer . Muscle biopsies were taken , and performance tests were carried out before and after the training period . Similar increases in maximal O(2 ) uptake ( 8.3 - 13.1 % ) and maximal power output ( 11.4 - 20.8 % ) were found in all groups . RT-PCR revealed elevated mRNA concentrations of the alpha-subunit of hypoxia-inducible factor 1 ( HIF-1 ) after both high- ( + 82.4 % ) and low (+78.4%)-intensity training under hypoxic conditions . The mRNA of HIF-1alpha(736 ) , a splice variant of HIF-1alpha newly detected in human skeletal muscle , was shown to be changed in a similar pattern as HIF-1alpha . Increased mRNA contents of myoglobin ( + 72.2 % ) and vascular endothelial growth factor ( + 52.4 % ) were evoked only after high-intensity training in hypoxia . Augmented mRNA levels of oxidative enzymes , phosphofructokinase , and heat shock protein 70 were found after high-intensity training under both hypoxic and normoxic conditions . Our findings suggest that HIF-1 is specifically involved in the regulation of muscle adaptations after hypoxia training . Fine-tuning of the training response is recognized at the molecular level , and with less sensitivity also at the structural level , but not at global functional responses like maximal O(2 ) uptake or maximal power output PURPOSE Recent studies have shown that low-intensity resistance training with vascular occlusion ( kaatsu training ) induces muscle hypertrophy . A local hypoxic environment facilitates muscle hypertrophy during kaatsu training . We postulated that muscle hypertrophy can be more efficiently induced by placing the entire body in a hypoxic environment to induce muscle hypoxia followed by resistance training . METHODS Fourteen male university students were r and omly assigned to  hypoxia ( Hyp ) and normoxia ( Norm ) groups ( n = 7 per group ) . Each training session proceeded at an exercise intensity of 70 % of 1 repetition maximum ( RM ) , and comprised four sets of 10 repetitions of elbow extension and flexion . Students exercised twice weekly for 6 wk and then muscle hypertrophy was assessed by magnetic resonance imaging and muscle strength was evaluated based on 1RM . RESULTS Muscle hypertrophy was significantly greater for the Hyp-Ex ( exercised flexor of the hypoxia group ) than for the Hyp-N ( nonexercised flexor of the hypoxia group ) or Norm-Ex flexor ( P < .05 , Bonferroni correction ) . Muscle hypertrophy was significantly greater for the Hyp-Ex than the Hyp-N extensor . Muscle strength was significantly increased early ( by week 3 ) in the Hyp-Ex , but not in the Norm-Ex group . CONCLUSION This study suggests that resistance training under hypoxic conditions improves muscle strength and induces muscle hypertrophy faster than under normoxic conditions , thus representing a promising new training technique In skeletal muscle , phosphocreatine ( PCr ) recovery from submaximal exercise has become a reliable and accepted measure of muscle oxidative capacity . During exercise , O2 availability plays a role in determining maximal oxidative metabolism , but the relationship between O2 availability and oxidative metabolism measured by 31P-magnetic resonance spectroscopy ( MRS ) during recovery from exercise has never been studied . We used 31P-MRS to study exercising human gastrocnemius muscle under conditions of varied fractions of inspired O2 ( FIO2 ) to test the hypothesis that varied O2 availability modulates PCr recovery from submaximal exercise . Six male subjects performed three bouts of 5-min steady-state submaximal plantar flexion exercise followed by 5 min of recovery in a 1.5-T magnet while breathing three different FIO2 concentrations ( 0.10 , 0 . 21 , and 1.00 ) . Under each FIO2 treatment , the PCr recovery time constants were significantly different , being longer in hypoxia [ 33 . 5 + /- 4.1 s ( SE ) ] and shorter in hyperoxia ( 20.0 + /- 1.8 s ) than in normoxia ( 25.0 + /- 2.7 s ) ( P < /= 0.05 ) . End-exercise pH was not significantly different among the three treatments ( 7.08 + /- 0.01 for 0.10 , 7.04 + /- 0.01 for 0.21 , and 7.04 + /- 0.02 for 1.00 ) . These results demonstrate that PCr recovery is significantly altered by FIO2 and suggest that , after submaximal exercise , PCr recovery , under normoxic conditions , is limited by O2 availability Flaws in the design , conduct , analysis , and reporting of r and omised trials can cause the effect of an intervention to be underestimated or overestimated . The Cochrane Collaboration ’s tool for assessing risk of bias aims to make the process clearer and more Purpose The aim of this study was to analyze the effect of hypoxia on metabolic and acid – base balance , blood oxygenation , electrolyte , and half-squat performance variables during high-resistance circuit ( HRC ) training . Methods Twelve resistance-trained subjects participated in this study . After a 6RM testing session , participants performed three r and omized trials of HRC : normoxia ( NORM : FiO2 = 0.21 ) , moderate hypoxia ( MH : FiO2 = 0.16 ) , or high hypoxia ( HH : FiO2 = 0.13 ) , separated by 72 h of recovery in normoxic conditions . HRC consisted of two blocks of three exercises ( Block 1 : bench press , deadlift and elbow flexion ; Block 2 : half-squat , triceps extension , and ankle extension ) . Each exercise was performed at 6RM . Rest periods lasted for 35 s between exercises , 3 min between sets , and 5 min between blocks . Peak and mean force and power were determined during half-squat . Metabolic , acid – base balance , blood oxygenation and electrolyte variables , arterial oxygen saturation ( SaO2 ) , and rating of perceived exertion ( RPE ) were measured following each block . Results During the first set , peak force and power were significantly lower in HH than MH and NORM ; whereas in the second set , mean and peak force and power were significantly lower in HH than NORM . At the end of the HRC training  session , blood lactate and RPE in HH were significantly higher than in MH and NORM . SaO2 , pH , HCO3− , and pO2 values were significantly lower in all hypoxic conditions than in NORM . Conclusion These results indicate that simulated hypoxia during HRC exercise reduce blood oxygenation , pH , and HCO3− , and increased blood lactate ultimately decreasing muscular performance Abstract The aim of the present study was to evaluate the effects of a 6 week resistance training protocol under hypoxic conditions ( FiO2 = 12.9 % , 4000 m ) on muscle hypertrophy . The project included 12 resistance trained male subjects , r and omly divided into two experimental groups . Group 1 ( n = 6 ; age 21 ± 2.4 years ; body height [ BH ] 178.8 ± 7.3 cm ; body mass [ BM ] 80.6 ± 12.3 kg ) and group 2 ( n = 6 ; age 22 ± 1.5 years ; BH 177.8 ± 3.7 cm ; BM 81.1 ± 7.5 kg ) . Each group performed resistance exercises alternately under normoxic and hypoxic conditions ( 4000 m ) for 6 weeks . All subjects followed a training protocol that comprised two training sessions per week at an exercise intensity of 70 % of 1RM ; each training session consisted of eight sets of 10 repetitions of the bench press and barbell squat , with 3 min rest periods . The results indicated that strength training in normobaric hypoxia caused a significant increase in BM ( p < 0.01 ) and fat free mass ( FFM ) ( p < 0.05 ) in both groups . Additionally , a significant increase ( p < 0.05 ) was observed in IGF-1 concentrations at rest after 6 weeks of hypoxic resistance training in both groups . The results of this study allow to conclude that resistance training ( 6 weeks ) under normobaric hypoxic conditions induces greater muscle hypertrophy compared to training in normoxic conditions OBJECTIVES To investigate the effect of blood flow restriction or normobaric hypoxic exposure combined with low-load resistant exercise ( LRE ) , on muscular strength and endurance . DESIGN A r and omised controlled trial . METHODS Well-trained netball players ( n=30 ) took part in a 5 weeks training of knee flexor and extensor muscles in which LRE ( 20 % of one repetition maximum ) was combined with ( 1 ) an occlusion pressure of approximately 230mmHg around the upper thigh ( KT , n=10 ) , ( 2 ) hypoxic air to generate blood oxyhaemoglobin levels of approximately 80 % ( HT , n=10 ) or ( 3 ) with no additional stimulus ( CT , n=10 ) . The training was of the same intensity and amount in all groups . One to five days before and after training , participants performed a series of strength and endurance tests of the lower limbs ( 3-s maximal voluntary contraction [ MVC3 ] , area under 30-s force curve [ MVC30 ] , number of repetitions at 20 % 1RM [ Reps201RM ] ) . In addition , the cross-sectional area ( CSA ) of the quadriceps and hamstrings were measured . RESULTS Relative to CT , KT and HT increased MVC3 ( 11.0±11.9 % and 15.0±13.1 % ) , MVC30 ( 10.2±9.0 % and 18.3±17.4 % ) and Reps201RM ( 28.9±23.7 % and 23.3±24.0 % , mean±90 % confidence interval ) after training . CSA increased by 6.6±4.5 % , 6.1±5.1 % and 2.9±2.7 % in the KT , HT and CT groups respectively . CONCLUSIONS LRE in conjunction with 
    Output:
    
Although RTH  improved muscle size and strength , this protocol did not provide significant benefit over resistance training in normoxia .