***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: We examined gender differences in growth hormone ( GH ) secretion during rest and exercise .  Eighteen subjects ( 9 women and 9 men ) were tested on two occasions each [ resting condition ( R ) and exercise condition ( Ex ) ] . Blood was sample d at 10-min intervals from 0600 to 1200 and was assayed for GH by chemiluminescence . At R , women had a 3.69-fold greater mean calculated mass of GH secreted per burst compared with men ( 5.4 + /- 1.0 vs. 1.7 + /- 0.4 microg/l , respectively ) and higher basal ( interpulse ) GH secretion rates , which result ed in greater GH production rates and serum GH area under the curve ( AUC ; 1,107 + /- 194 vs. 595 + /- 146 microg x l(-1 ) x min , women vs. men ; P = 0.04 ) . Compared with R , Ex result ed in greater mean mass of GH secreted per burst , greater mean GH secretory burst amplitude , and greater GH AUC ( 1,196 + /- 211 vs. 506 + /- 90 microg x l(-1 ) x min , Ex vs. R , respectively ; P < 0.001 ) . During Ex , women attained maximal serum GH concentrations significantly earlier than men ( 24 vs. 32 min after initiation of Ex , respectively ; P = 0.004 ) . Despite this temporal disparity , both genders had similar maximal serum GH concentrations . The change in AUC ( adjusted for unequal baselines ) was similar for men and women ( 593 + /- 201 vs. 811 + /- 268 microg x l(-1 ) x min ) , but there were significant gender-by-condition interactive effects on GH secretory burst mass , pulsatile GH production rate , and maximal serum GH concentration . We conclude that , although women exhibit greater absolute GH secretion rates than men both at rest and during exercise , exercise evokes a similar incremental GH response in men and women . Thus the magnitude of the incremental secretory GH response is not gender dependent INTRODUCTION This study examined the effects of short-term physical training on the acute hormonal response ( i.e. , growth hormone , total and free insulin-like growth factor I [ IGF-I ] , and IGF binding proteins [IGFBP]-1 , IGFBP-2 , and IGFBP-3 ) to resistance exercise ( RE ) in women . METHODS Forty-six women ( 20.3 ± 0.3 yr , mass = 64.1 ± 7.3 kg , height = 165.7 ± 1.0 cm ) were r and omly assigned to an endurance training ( E ) , resistance training ( R ) , combined training ( R + E ) , or control ( C ) group for 8wk . Subjects completed a st and ardized bout of RE ( six sets of back squats at 10 repetition maximum ) before and after training . Blood sample s were obtained at rest ( PRE ) , after the third set , immediately postexercise ( POST ) , and at 15 min and 30 min after exercise . RESULTS Acute RE significantly increased ( P < 0.05 ) serum growth hormone ( mean ± SD ; change from PRE to POST = + 10.9 ± 7.5 μg·L-1 ) , total IGF-I ( + 66.1 ± 25.4 μg·L-1 ) , IGFBP-1 ( + 2.5 ± 3.1 μg·L-1 ) , IGFBP-2 ( + 86.0 ± 86.8 μg·L-1 ) , and IGFBP-3 ( + 0.69 ± 0.25 mg·L-1 ) concentrations and decreased free IGF-I concentrations ( -0.14 ± 0.21 μg·L-1 ) . After 8 wk of training , total IGF-I concentrations were significantly increased ( change in POST concentrations from week 0 to week 8 = + 82.5 ± 120.8 μg·L-1 ) , and IGFBP-1 concentrations were significantly decreased ( -6.7 ± 13.6 μg·L-1 ) during exercise in groups that participated in resistance training ( R and R + E ) ; no significant changes were seen after E or C. CONCLUSIONS Participation in resistance training increased total IGF-I and reduced IGFBP-1 concentrations during acute RE , indicating exercise mode-specific adaptations in the circulating IGF-I system We examined the relationship between physical fitness and circulating components of the GH-insulin-like growth factor I ( IGF-I ) system [ i.e. GH , GH-binding protein ( GHBP ) , IGF-I , and IGF-binding proteins 1 - 5 ( IGFBP-1 through-5 ) ] in adolescent females ( age range , 15 - 17 yr ) . The study consisted of 1 ) a cross-sectional protocol ( n = 23 ) in which GH-IGF-I components were correlated with fitness , as estimated by thigh muscle volume and maximal O2 uptake ; and 2 ) a prospect i ve study in which fitness , GH-IGF-I system components , and osteocalcin were examined before and after a 5-week period of endurance-type training ( control , n = 6 ; trained , n = 10 ) . The cross-sectional analysis revealed significant ( P < 0.05 ) positive correlations between fitness and 1 ) mean 12-h overnight GH levels , 2 ) GHBP , and 3 ) IGF-I. Muscle volume was negatively correlated with both IGFBP-2 and -4 . The prospect i ve training study was associated with 1 ) increases in circulating osteocalcin ( 39 + /- 14 % ; P < 0.007 ) , and 2 ) decreases in IGF-I ( -14 + /- 5 % ; P < 0.05 ) and IGFBP-5 ( -10 + /- 4 % ; P < 0.04 ) . Unexpectedly , IGFBP-3 fell in both control (-8 + /- 2 % ; P < 0.01 ) and trained subjects ( -5 + /- 3 % ; P < 0.05 ) , and GHBP was reduced only among control subjects ( -10 + /- 7 % ; P < 0.04 ) . In summary , fitter adolescent girls tended to have increased mean serum GH , GHBP , and IGF-I. In contrast , brief endurance training led to increases in muscle mass and serum osteocalcin that were not accompanied by increases in GH or IGF-I. In fact , training may , in the short term , have led to a catabolic state hormonally expressed by reductions in IGF-I and IGFBP-5 The purpose of this study was to determine the impact of dietary factors and exercise-associated factors on the response of IGF-I and its binding proteins ( IGFBPs ) during a period of increased physical activity . Twenty-nine men completed a 4-day ( days 1 - 4 ) baseline period of a controlled energy balanced diet while maintaining their normal physical activity level followed by 7 days ( days 5 - 11 ) of a 1,000 kcal/day increase in physical activity above their normal activity levels . Two subject groups , one sedentary ( Sed , mean Vo(2peak ) : 39 mlxkg(-1)xmin(-1 ) , n = 7 ) and one fit ( FIT1 , mean Vo(2peak ) : 56 ml.kg(-1)xmin(-1 ) , n = 8) increased energy intake to maintain energy balance throughout the 7-day intervention . In two other fit subject groups ( FIT2 , n = 7 and FIT3 , n = 7 ) , energy intake remained at baseline result ing in a 1,000 kcal/day exercise-induced energy deficit . Of these , FIT2 received an adequate protein diet ( 0.9 g/kg ) , and FIT3 received a high-protein diet ( 1.8 g/kg ) . For all four groups , IGF-I , IGFBP-3 , and the acid labile subunit ( ALS ) were significantly decreased by day 11 ( 27 + /- 4 % , 10 + /- 2 % , and 19 + /- 4 % , respectively ) and IGFBP-2 significantly increased by 49 + /- 21 % following day 3 . IGFBP-1 significantly increased only in the two negative energy balance groups , FIT2 ( 38 + /- 6 % ) and FIT3 ( 46 + /- 8 % ) . Differences in initial fitness level and dietary protein intake did not alter the IGF-I system response to an acute increase in physical activity . Decreases in IGF-I were observed during a moderate increase in physical activity despite maintaining energy balance , suggesting that currently unexplained exercise-associated mechanisms , such as increased energy flux , regulate IGF-I independent of energy deficit OBJECTIVE To study interstitial IGF-I concentrations in resting and exercising skeletal muscle in relation to the circulating components of the IGF-IGF binding protein ( IGFBP ) system . DESIGN AND METHODS Seven women performed endurance exercise with 1 leg ( Ex-leg ) for 1 h. The resting leg ( Rest-leg ) served as a control . IGF-I was determined in microdialysate ( MD ) and was compared with veno-arterial ( v-a ) concentrations of circulating IGF-IGFBP components . RESULTS Median ( range ) basal MD-IGF-I was 0.87 ( 0.4 - 1.5 ) microg/l or 0.4 (0.2)% of total-IGF-I ( t-IGF-I ) determined in arterial serum and in the same concentration range as free dissociable IGF-I ( f-IGF-I ) . Rest-leg MD-IGF-I decreased , reaching significance after exercise . Ex-leg MD-IGF-I was unchanged during exercise and declined after exercise at the level of significance ( P = 0.05 ) . There was a release of f-IGF-I from the Ex-leg into the circulation at the end of and shortly after exercise . A small but significant increase in circulating IGFBP-1 was detected at the end of exercise and IGFBP-1 increased further after exercise . Although interleukin-6 ( IL-6 ) has been associated with IGFBP-3 proteolysis , the circulating molecular forms of IGFBP-3 remained unchanged in spite of an IL-6 release from the muscle compartment . CONCLUSIONS Circulating IGFBP-1 is related to interstitial IGF-I in resting muscle although the temporal relationship may not be simple . Further studies should explore the role of local release of IGF-I and its impact on IGF-I activity during contraction Acute resistance exercise and L-arginine have both been shown to independently elevate plasma growth hormone ( GH ) concentrations ; however , their combined effect is controversial . The purpose was to investigate the combined effects of resistance exercise and L-arginine supplementation on plasma L-arginine , GH , GH secretagogues , and IGF-1 in strength trained participants . Fourteen strength trained males ( age : 25 ± 4 y ; body mass : 81.4 ± 9.0 kg ; height : 179.4 ± 6.9 cm ; and training experience : 6.3 ± 3.4 y ) participated in a r and omized double-blind crossover design ( separated by ~7 days ) . Subjects reported to the laboratory at 08:00 in a fasted state , consumed L-arginine ( ARG ; 0.075 g·kg-1 body mass ) or a placebo ( PLA ) before performing an acute bout of resistance exercise ( 3 sets of 8 exercises , 10 repetitions at ~75 % 1RM ) . Blood sample s were collected at rest , before exercise , and at 0 , 15 , 30 , and 60 min of rest-recovery . The ARG condition significantly increased plasma L-arginine concentrations ( ~120 % ) while no change was detected in the PLA condition . There were no differences between conditions for GH , GH-releasing hormone , ghrelin , or IGF-1 at any time point . GH-inhibiting hormone was significantly lower in the ARG condition . However , integrated area under the curve for GH was blunted in the ARG condition ( L-arginine = 288.4 ± 368.7 vs. placebo = 487.9± 482.0 min·ng·mL1 , p < .05 ) . L-arginine ingested before resistance exercise significantly elevated plasma L-arginine concentration but attenuated plasma GH in strength trained individuals despite a lower GHIH . Furthermore our data shows that the GH suppression was not due to a GH or IGF-1 induced autonegative feedback loop Taylor , LW , Wilborn , CD , Kreider , RB , and Willoughby , DS . Effects of resistance exercise intensity on extracellular signal-regulated kinase 1/2 mitogen-activated protein kinase activation in men . J Strength Cond Res 26(3 ) : 599–607 , 2012—Extracellular signal-regulated kinase ( ERK ) 1/2 signaling has been shown to be increased after heavy resistance exercise and suggested to play a role in the hypertrophic adaptations that are known to occur with training . However , the role that ERK1/2 may play in response to lower intensities of resistance exercise is unknown . Therefore , the purpose of this study was to determine the effects of resistance exercise intensity on ER 
    Output:
    
The present study showed that IGF-1 serum concentrations are altered by exercise type , but in conditions which are not well-defined .
The systematic review and meta- analysis suggest that there is no determinant in serum IGF-1 changes for the exercise load characteristic .
Therefore , physical exercise may be an alternative treatment to control changes in IGF-1 metabolism and blood concentration