***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: This study was design ed to assess the effect of performance feedback on stress reactivity after recovery from maximal exercise . Forty competitive athletes were recruited to complete a maximal exercise test .  Performance feedback was manipulated after the exercise test to give four groups : ( 1 ) high performance , ( 2 ) low performance , ( 3 ) accurate feedback and ( 4 ) no exercise control .  Cardiovascular reactivity was assessed during psychological stress . The results indicate that accurate feedback participants experienced lower relative reactivity to stress ( lower mean arterial pressure ) than their no-exercise counterparts . These results demonstrate that the stressbuffering effect of exercise extends to maximal exercise . In addition , high-performance participants experienced lower relative reactivity than low-performance participants . Thus , low-performance feedback was sufficient to remove the buffering effect of exercise . There were no differences between the high-performance and accurate feedback conditions , or between the low-performance and control conditions Endogenous opiate peptides can regulate neuroendocrine and circulatory responses to behavioral stress and may be important in the pathogenic effects of sympathoadrenal reactivity . We tested this hypothesis by examining the effect of the opiate antagonist naloxone on blood pressure responses to behavioral stress in young adults with high , medium , or low casual blood pressures .  Naloxone increased mean arterial pressure responses to stress in subjects with low casual pressure , but had no significant effect on responses in subjects with high casual pressure . These results suggest opioidergic inhibition of sympathetic nervous system responses may be deficient in persons at risk for essential hypertension Thirty-six competitive sportsmen and 36 inactive men participated in a two-session experiment . Session 1 involved exercise to exhaustion so as to assess maximal oxygen consumption ( VO2 max ) . In Session 2 , both groups were r and omized into three experimental conditions : 20 min of exercise at high intensity ( 70 % VO2max ) or moderate intensity ( 50 % VO2max ) or a light exercise control . Following 30 min of recovery , all subjects performed mental arithmetic and public speech tasks in a counterbalanced order . Cardiovascular , electrodermal , respiratory , and subjective variables were recorded . Sportsmen had higher VO2max , lower body fat  , and lower resting heart rate ( HR ) than inactive men . A postexercise hypotensive response was observed among subjects in the 70 % and 50 % VO2max conditions , accompanied by baroreceptor reflex inhibition in the 70 % condition . Systolic pressure was lower during mental arithmetic and during recovery from the speech task in the high-intensity than in the control group . Diastolic pressure was lower following mental arithmetic in the high-intensity group . No differences in HR reactivity , electrodermal , or respiratory parameters were observed , but baroreceptor reflex sensitivity was inhibited during mental arithmetic . The results are discussed in relation to previous reports of suppressed cardiovascular reactivity to mental stress tests following vigorous exercise and the role of stress-related processes in the antihypertensive response to physical training The effects of exercise on subsequent psychophysiological responses to mental stress were assessed in a study of 30 normotensive male volunteers . Participants were r and omly allocated to three experimental conditions--20-min exercise at 100 Watts ( high exercise ) , 20-min exercise at 25 Watts ( low exercise ) , or 20-min no exercise ( control ) . After a recovery period of 20 min , all subjects performed a mental arithmetic task for four 5-min trials . Blood pressure and heart rate were monitored continuously using a Finapres , and respiration and electrodermal activity were also recorded . Baroreceptor reflex control of heart rate was assessed using power spectrum analysis . Exercise produced consistent increases in systolic blood pressure , heart rate , and subjective tension , together with reductions in systemic resistance and baroreflex sensitivity . The systolic and diastolic blood pressure and heart rate reactions to mental arithmetic were significantly blunted in the high exercise compared with control conditions , with the low exercise group showing an intermediate pattern . Subjective responses to mental stress were unaffected by prior exercise . The pattern of hemodynamic response was not a result of changes in baroreflex sensitivity . The mechanisms underlying this result are discussed in relation to the discrepancies between subjective and physiological responses to mental stress , and the implication s for the use of exercise in stress management This investigation compared patterns of regional cerebral blood flow ( rCBF ) during exercise recovery both with and without postexercise hypotension ( PEH ) . Eight subjects were studied on 3 days with r and omly assigned conditions : 1 ) after 30 min of rest ; 2 ) after 30 min of moderate exercise ( M-Ex ) at 60 - 70 % heart rate ( HR ) reserve during PEH ; and 3 ) after 30 min of light exercise ( L-Ex ) at 20 % HR reserve with no PEH . Data were collected for HR , mean blood pressure ( MBP ) , and ratings of perceived exertion and relaxation , and rCBF was assessed by use of single-photon-emission computed tomography . With the use of ANOVA across conditions , there were differences ( P < 0.05 ; mean + /- SD ) from rest during exercise recovery from M-Ex ( HR = + 12 + /- 3 beats/min ; MBP = -9 + /- 2 mmHg ) , but not from L-Ex ( HR = + 2 + /- 2 beats/min ; MBP = -2 + /- 2 mmHg ) . After M-Ex , there were decreases ( P < 0.05 ) for the anterior cingulate ( -6.7 + /- 2 % ) , right and left inferior thalamus ( -10 + /- 3 % ) , right inferior insula ( -13 + /- 3 % ) , and left inferior anterior insula (-8 + /- 3 % ) , not observed after L-Ex . There were rCBF decreases for leg sensorimotor regions after both M-Ex ( -15 + /- 4 % ) and L-Ex ( -12 + /- 3 % ) and for the left superior anterior insula ( -7 + /- 3 % and -6 + /- 3 % ) , respectively . Data show that there are rCBF reductions within specific regions of the insular cortex and anterior cingulate cortex coupled with a postexercise hypotensive response after M-Ex . Findings suggest that these cerebral cortical regions , previously implicated in cardiovascular regulation during exercise , may also be involved in PEH The role of endogenous opioids in aerobic fitness-induced decrements in cardiovascular stress reactivity was examined by comparing the effects of opioid antagonism with naltrexone on responses to stress in young adults with high versus low levels of aerobic fitness . Two hundred forty subjects were given an  activity question naire and males with the highest ( Fit ) and lowest ( Nonfit ) aerobic activity profiles were recruited for maximal oxygen consumption ( VO2max ) treadmill testing and psychological stress testing ( final sample N = 28 ) . Heart rate and blood pressures were measured during performance on a computer-controlled arithmetic task after pretreatment with either naltrexone ( Trexan , DuPont ) or a placebo . During placebo challenges , Fit subjects , compared with Nonfit , showed lower heart rate reactivity during stress and lower mean arterial blood pressures immediately before and during recovery from stress . Naltrexone eliminated these reactivity differences by increasing heart rate reactivity and raising mean arterial blood pressure in Fit subjects . These data suggest that aerobic fitness is associated with enhanced opioidergic inhibition of circulatory stress reactivity . Opioidergic modulatory effects on stress reactivity may comprise an important mechanism in fitness-associated risk reduction for cardiovascular disease We evaluated the experimental hypothesis that an acute bout of aerobic exercise ( AE ) serves as a buffer to psychosocial stress responses in low to moderate physically fit women . Forty-eight ( 24 White , 24 Black ) 25- to 40-year-old women participated in two counterbalanced experimental conditions : an attention control and a 40-min bout of AE at 70 % heart rate ( HR ) reserve . The attention control and AE treatments were followed by ( a ) 30 min of quiet rest , ( b ) exposure to mental and interpersonal threat , and ( c ) 5 min of recovery .  Blood pressure ( BP ) and HR were monitored at baseline , during the stressors , and throughout recovery . Self-reported distress was assessed before each stressor and upon completion of the recovery period . The results provided clear evidence that exercise dampens BP reactivity to psychosocial stress . Additionally , compared with the attention placebo control , AE reduced both the frequency and intensity of anxiety-related thoughts that occur in anticipation of interpersonal threat and challenge We examined the correspondence between laboratory measures of cardiovascular reactivity ( CVR ) and within-person changes in cardiovascular activity during the challenges of daily life , after adjustment for posture , activity , and other effects . Healthy adults ( n = 335 ) were administered laboratory measures of CVR along with 6 days of  ambulatory blood pressure monitoring and electronic diary reports . Compared with low reactors , high laboratory systolic blood pressure ( SBP ) reactors showed larger increases in SBP during periods of high task dem and or low decisional control in daily life . High diastolic blood pressure ( DBP ) reactors showed larger increases in ambulatory DBP during situations rated as both low control and high dem and . This multilevel modeling approach may enhance our ability to detect the correspondence between laboratory and ambulatory measures of CVR , and to identify the circumstances under which it may be most clearly observed BACKGROUND The study objective was to determine the health and quality -of-life effects of moderate-intensity exercise among older women family caregivers . METHODS This 12-month r and omized controlled trial involved a volunteer sample of 100 women aged 49 to 82 years who were sedentary , free of cardiovascular disease , and caring for a relative with dementia . Participants were r and omized to 12 months of home-based , telephone-supervised , moderate-intensity exercise training or to an attention-control ( nutrition education ) program . Exercise consisted of four 30- to 40-minute endurance exercise sessions ( brisk walking ) prescribed per week at 60 % to 75 % of heart rate reserve based on peak treadmill exercise heart rate . Main outcomes were stress-induced cardiovascular reactivity levels , rated sleep quality , and reported psychological distress . RESULTS Compared with nutrition participants ( NU ) , exercise participants ( EX ) showed significant improvements in the following : total energy expenditure ( baseline and post-test means [ SD ] for EX = 1.4 [ 1.9 ] and 2.2 [ 2.2 ] kcal/kg/day ; for NU = 1.2 [ 1.7 ] and 1.2 [ 1.6 ] kcal/kg/day ; p < .02 ) ; stress-induced blood pressure reactivity ( baseline and post-test systolic blood pressure reactivity values for EX = 21.6 [ 12.3 ] and 12.4 [ 11.2 ] mm Hg ; for NU = 17.9 [ 10.2 ] and 17.7 [ 13.8 ] mm Hg ; p < .024 ) ; and sleep quality ( p < .05 ) . NU showed significant improvements in percentages of total calories from fats and saturated fats relative to EX ( p values < .01 ) . Both groups reported improvements in psychological distress . Conclusions . Family caregivers can benefit from initiating a regular moderate-intensity exercise program in terms of reductions in stress-induced cardiovascular reactivity and improvements in rated sleep quality Objectives : Mild to moderate acute , endurance exercise has generally been shown to reduce blood pressure ( BP ) in hypertensive ( HT ) individuals . Whether a slightly more strenuous bout of exercise can elicit a greater and more prolonged BP reduction is unknown . Therefore , the purpose of this study was to examine the effects of two , 30-min exercise bouts , conducted at 50 % and 75 % of maximal oxygen uptake ( VO2max ) , on the quantity and quality of BP reduction over a 24-h period . Methods : Sixteen , Stage 1 and 2 non-medicated , HT ( 8 men/8 women ) subjects were matched with normotensive ( NT ) men and women ( n = 16 ) . All subjects were evaluated for VO2max with a symptom-limited treadmill test and then completed a 30-min exercise bout at 50 % and 75 % of VO2max as well as a control ( no exercise ) session in r and om fashion on separate days . Twenty-four hour ambulatory BPs were measured after both the exercise and control setting s. Data was assessed at 1 , 3 , 6 , 12 , and 24 h post-exercise and control session . Results : A repeated- measures ANOVA showed non-significant differences between HT men and women and that both exercise intensities , relative to the control session , significantly ( P < 0.05 ) reduced systolic ( s ) and diastolic ( d ) bps . nt subjects showed non-significant reductions following both intensities . the reductions in the ht men and women averaged 4 and 9 mm hg (sbp)/5 and 7 mm hg ( dbp ) for 50 % and 75 % , respectively . on average , the ht subjects ( men and women combined ) maintained significant sbp reductions for 13 h after the 75 % bout compared to 4 h after the 50 % intensity . likewise , dbp was reduced for an average of 11 h following the 75 % bout compared to 4 h after the 50 % intensity . Conclusions : These results suggest that an exercise bout conducted between 50–75 % VO2max significantly decreases SBP and DBP in HT subjects and that a greater and longer-lasting absolute reduction is evident following a 75 % of maximum bout of exercise The effect of 30 min of cycling exercise at 60 % VO2max on hemodynamic responses to the Stroop and cold pressor tests in 12 norm 
    Output:
    
In conclusion , an acute bout of aerobic exercise appears to have a significant impact on the BP response to a psychosocial stressor