***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: Background Cross-sectional studies have suggested that elevated cortisol is associated with worse physical performance , a surrogate of ageing . We examined the relationship between repeat cortisol measures over 20 years and physical performance in later life . Methods Middle-aged men ( 45–59 years ) were recruited between 1979 and 1983 ( Phase 1 ) from the Caerphilly Prospect i ve Study ( CaPS ) and re-examined 20 years later at 65–83 years of age ( Phase 5 ) . Participants included 750 and 898 subjects with either Phase 1 and /or Phase 5 data on exposure and outcomes . Outcome measures were walking speed and balance time and exposures included morning fasting serum cortisol ( Phase 1 ) and four salivary sample s on 2 consecutive days ( Phase 5 ) . Results Faster walking speed was associated with higher morning cortisol at Phase 1 [ coefficient per st and ard deviation ( SD ) increase 0.68 , 95 % confidence interval ( 95 % CI ) 0.09–1.27 ; P = 0.02 ] though this was attenuated after adjustment for covariates ( coefficient per SD increase 0.45 ; 95 % CI –0.16 to 1.07 ; P = 0.15 ) . Higher night-time cortisol at Phase 5 was associated with slower speed ( coefficient per SD increase –1.06 ; 95 % CI –1.60 to –0.52 ; P < 0.001 ) and poorer balance ( odds ratio of top tertile vs bottom 2.49 ; 95 % CI 1.63–3.81 ; P < 0.001 ) . Worst performance was seen for men with a poor morning response ( Phase 1 ) and less nocturnal decline ( Phase 5 ) . Conclusions Dysregulation of the hypothalamic pituitary adrenal ( HPA ) axis is associated with worse physical performance in later life . This may reflect a causal effect of the HPA axis on ageing or that ageing itself is associated with reduced HPA reactivity BACKGROUND Stress and mental fatigue are major health threats to employees in office-based occupations .  Physical activity is widely used as a stress-management intervention for employees . Moreover , experiences in contact with nature have been shown to provide stress-reduction and restoration from mental fatigue . OBJECTIVES In a pilot study design ed as a r and omized controlled trial we investigated the impact of a green-exercise intervention on psychological and physiological indicators of stress in municipality employees . METHODS Fourteen employees ( 7 females and 7 males , 49±8 yrs ) volunteered in an exercise-based intervention in workplace either outdoors in a green/nature area or in an indoor exercise- setting . The intervention consisted of an information meeting and two exercise sessions , each including a biking bout and a circuit-strength sequence using elastic rubber b and s ( 45-minutes , at about 55 % of HR reserve , overall ) . Main outcomes were perceived environmental potential for restoration , affective state , blood pressure ( BP ) and cortisol awakening response ( CAR AUC(G ) and CAR AUC(I ) ) and cortisol levels in serum . Measurements were taken at baseline and in concomitance with the exercise sessions . Furthermore , affective state and self-reported physical activity levels were measured over a 10-weeks follow-up period . RESULTS Compared with the indoor group , the nature group reported higher environmental potential for restoration ( p < 0.001 ) and Positive Affect ( p < 0.01 ) , along with improved CAR AUC(I ) ( p = 0.04 ) and , marginally , diastolic BP ( p = 0.05 ) . The nature group also reported higher ratings of Positive Affect at follow-up ( p = 0.02 ) . Differences at post-exercise were not found for any of the other components of affective state , systolic BP , CAR AUC(G ) and cortisol levels measured in serum . CONCLUSIONS Green-exercise at the workplace could be a profitable way to manage stress and induce restoration among employees . Further studies on larger sample s are needed in order to improve the generalizability of the results Psychological distress and elevated cortisol secretion promote abdominal fat , a feature of the Metabolic Syndrome . Effects of stress reduction interventions on abdominal fat are unknown . Forty-seven overweight/obese women ( mean BMI = 31.2 ) were r and omly assigned to a 4-month intervention or waitlist group to explore effects of a mindfulness program for stress eating . We assessed  mindfulness , psychological distress , eating behavior , weight , cortisol awakening response ( CAR ) , and abdominal fat ( by dual-energy X-ray absorptiometry ) pre- and posttreatment . Treatment participants improved in mindfulness , anxiety , and external-based eating compared to control participants . Groups did not differ on average CAR , weight , or abdominal fat over time . However , obese treatment participants showed significant reductions in CAR and maintained body weight , while obese control participants had stable CAR and gained weight . Improvements in mindfulness , chronic stress , and CAR were associated with reductions in abdominal fat . This proof of concept study suggests that mindfulness training shows promise for improving eating patterns and the CAR , which may reduce abdominal fat over time Burnout is presumed to be the result of chronic stress , and chronic stress is known to affect the HPA-axis . To date , studies on HPA-axis functioning in burnout have showed inconsistent results . In the present study , a large sample ( n=74 ) of clinical ly diagnosed burnout individuals , mostly on sick-leave , were included and compared with 35 healthy controls .  Salivary cortisol  was sample d on 2 days to determine the cortisol awakening response ( CAR ) and the day-curve . In addition , the dexamethasone suppression test ( DST ) was applied to assess the feedback efficacy of the HPA-axis . There were no differences observed in the CAR , day-curve or CAR after DST in the burnout group as compared to a healthy control group . Burnout shows overlap in symptoms with chronic fatigue syndrome ( CFS ) and depression . Therefore , differential changes in HPA-axis functioning that resemble the hypo-functioning of the HPA-axis in CFS , or rather the hyper-functioning of the HPA-axis in depression , might have obscured the findings . However , no effect of fatigue or depressive mood on HPA-axis functioning was found in the burnout group . We concluded that HPA-axis functioning in clinical ly diagnosed burnout participants as tested in the present study , seems to be normal The aim of this study was to address the effect of endurance training on tissue sensitivity to glucocorticoids ( GC ) in both resting and exercising conditions . In vitro dexamethasone inhibition of LPS-induced interleukin-6 secretion in cultures of peripheral monocytes was compared in  untrained subjects ( UT ) and in endurance-trained men ( ET ) at the end of a 2-h run and during exercise recovery . We demonstrated an in vitro plasticity of sensitivity of monocytes to GC in ET men , superimposed to changes in systemic cortisol concentrations ( plasma and saliva ) . Compared with sedentary men , similar resting cortisol levels in ET men are associated with decreased sensitivity of monocytes to GC 8 and 24 h after the end of the last training session ( P < 0.05 , ET vs. UT ) . Moreover , in these ET subjects , an acute bout of exercise increased the sensitivity of monocytes to GC ( at 1000 and 1200 ; ET vs. UT , P > 0.05 ) . This acute exercise-induced increase in tissue sensitivity to GC , which is synchronous with activation of the hypothalamo-pituitary adrenal axis , may act to shut off muscle inflammatory reaction and cytokine synthesis and then decrease exercise-induced muscle damage or inflammatory response . By contrast , the decreased sensitivity of monocytes to GC reported in ET men 24 h after the last bout of exercise may be related to the process of desensitization that may act to protect the body from prolonged , exercise-induced cortisol secretion . These acute and chronic effects of exercise on tissue sensitivity to GC demonstrate an adaptation of the hypothalamo-pituitary adrenal axis to repeated and prolonged exercise-induced increases in GC secretion Bright light exposure after awakening has been shown to elevate cortisol levels in healthy participants . The present study examined the effect of dawn simulation ( a treatment for seasonal affective disorder ) on the cortisol response to awakening and mood .  Twelve healthy participants were supplied with a dawn simulator ( The Natural Alarm Clock , Outside In , Cambridge Ltd ) , a bedside light that increases in intensity prior to awakening to approximately 250 lux over 30 mins when an audible alarm sounds . A counterbalanced study was performed on 4 consecutive normal weekdays , two of which were control days ( no dawn simulation ) and two experimental ( dawn simulation ) .  Saliva sample s were taken immediately on awakening then at 15 , 30 and 45 minutes post awakening on all 4 study -days . Total cortisol production during the first 45 mins after awakening was found to be significantly higher in the experimental condition than in the control condition . Participants also reported greater arousal in the experimental condition and there was a trend for an association between increased arousal and increased cortisol secretory activity under dawn simulation . This study provides supportive evidence for the role of light and the suprachiasmatic nucleus in the awakening cortisol response PURPOSE The effect of training variations on 24-h urinary cortisol/cortisone ( C/Cn ) ratio was investigated in highly trained swimmers to determine whether it could be a good marker of training stress and performance . METHODS Fourteen swimmers ( five female and nine male ) were tested after 4 wk of intense training ( IT ) , 3 wk of reduced training ( RT ) , and 5 wk of moderate training ( MT ) . At the end of each period , the swimmers performed in their best event at an official competition . Individual performances were expressed as a percentage of the previous season 's best performance . The fatigue state was evaluated with a question naire . RESULTS The C/Cn ratio was statistically different for the three periods ( IT : 1.10 + /- 0.7 , RT : 0.64 + /- 0.3 , and MT : 0.57 + /- 0.2 ) . The differences in the C/Cn ratio between two consecutive performances were related to the differences in performance ( r = -0.52 , P < 0.01 ) , and the C/Cn ratio was significantly related to the total training ( r = 0.32 , P < 0.05 ) and total score of fatigue ( TSF ) ( r = 0.35 , P < 0.03 ) over the follow-up period . Cn levels were related to the dryl and training ( r = -0.46 ; P < 0.01 ) and TSF ( r = -0.40 ; P < 0.02 ) . During IT , variations in the C/Cn ratio were related to the changes in the mean intensity ( r = -0.67 ; P < 0.02 ) and to TSF ( r = 0.69 ; P < 0.01 ) . CONCLUSION The 24-h C/Cn ratio was moderately related to both training and performance whereas Cn levels were only related to training . The C/Cn ratio could be a useful indicator for monitoring the overreaching state in elite swimmers The aim of the study was to examine the effects of strenuous training on the hypothalamic-pituitary-adrenal axis activity . Exercise tests and saliva collection s for analysis of awakening cortisol response ( ACR ) and midnight cortisol were performed before and after a 7-day period of intensified training in a group of 15 soccer players . Intensified training result ed in a performancedecrement as shown by the pre-post-training changes in maximal values of counter movement jump ( CMJ ) height ( p=0.008 ) . Cortisol assessment during the first 30 min after awakening showed significant increases both before and after the 7-day period and post-training ACR higher than pre-training ACR ( p<0.001 ) . Midnight cortisol also significantly increased after training ( mean±SD , before : 3.0±0.7 nmol/l vs after : 5.9±3.3 nmol/l ; p=0.017 ) . The analysis of individual data showed an important inter-individual variability in the pre-post-training changes : several subjects increased post-awakening peak of cortisol , rate of cortisol increase from awakening to peak , and area under the curve ( AUC ) values , whereas other subjects showed no training-related increases . Significant correlations were observed between pre-post-training change in CMJ and in the following variables : awakening cortisol ( r=0.74 ) , post-awakening peak of cortisol ( r=0.81 ) , rate of cortisol increase ( r=0.75 ) , and AUC ( r=0.79 ) . Briefly , the lower the performance decrease , the higher the training-associated ACR increase . These data could indicate that a dys-regulated adaptation to exercise occurred in athletes who experienced a higher performance decrease after training and lower ( or absent ) hormonal changes . Future studies are needed to eluci date the physiological determinants which underlie the exercise-elicited changes in ACR and in midnight cortisol levels and their value in predicting impaired adaptations to exercise Glucocorticoids can down-regulate immune activity , but acute stress has been reported to increase both cortisol and levels of plasma cytokines . We investigated individual differences in cortisol responses and their associations with proinflammatory cytokines , 
    Output:
    
The available literature suggests a threshold of exercise may be required to alter the HPA axis and affect CAR .