Physical activity and blood pressure responsiveness to the cold pressor test in normotensive young adult African-American males.

The aim of our study was to examine whether there is an association between blood pressure reactivity to the cold pressor test in African Americans who engaged in different levels of physical activity. We examined the systolic pressure, diastolic pressure, mean arterial blood pressure, heart rate, cardiac index, total peripheral resistance, and forearm blood flow during a two-minute cold pressor test in 15 aerobic, physically active and 15 physically inactive, normotensive young adult African-American males. Peak oxygen consumption varied as a function of physical activity, and was significantly higher in the physically active than in the physically inactive subjects (54.5 +/- 1.5 vs 36.8 +/- 0.7 ml kg(-1) min(-1)) (P<.05). During the cold pressor test, consisting of immersing the foot in ice water, the change in cardiovascular responses were similar between the physically active and the physically inactive groups. These results suggest that regular physical activity may not contribute to an attenuated blood pressure response to behavioral stress of the cold pressor test in normotensive young adult African-American males.

Aerobic exercise attenuates blood pressure reactivity to cold pressor test in normotensive, young adult African-American women.

Exaggerated blood pressure reactivity to behavioral stress has been observed in the African-American population, and such a pressor response is believed to play a role in hypertension. Regular aerobic exercise has been shown to exert an anti-hypertensive effect, and this may alter the blood pressure hyperreactivity observed in African Americans. To test the hypothesis that aerobic exercise attenuates pressor reactivity in African Americans, we studied eight healthy aerobically-trained normotensive African-American females and five similar sedentary females. The stress stimuli consisted of the cold pressor test with the foot immersed in ice water for two minutes. The aerobic exercise training protocol consisted of six weeks of jogging at 60-70% of peak oxygen uptake (VO2peak), three days/week for 35 min/exercise session. Systolic blood pressure, diastolic blood pressure, mean arterial blood pressure, heart rate, cardiac output, total peripheral resistance, and forearm blood flow were measured. Manifestation of a training effect was illustrated by a 24.1 +/- 0.2% increase in VO2peak (26.9 +/- 1.2 mL x kg(-1) min(-1) vs 35.4 +/- 1.6 mL x kg(-1) min(-1)) (P<.05). Within the exercise-trained group there was a 6.3 +/- .15% decrease in systolic pressure (129 +/- 4.6 mm Hg vs. 121 +/- 5.4 mm Hg) (P<.05), and a 5.0 +/- .05% decrement in mean arterial blood pressure (99 +/- 3.3 mm Hg vs 94 +/- 3.6 mm Hg) (P<.05) during the cold pressor test. Pressor reactivity to cold stress did not change in the untrained group. Measures of heart rate, cardiac output, total peripheral resistance, and forearm blood flow were unaltered during conditions of the cold pressor test. We conclude that aerobic exercise attenuates the blood pressure reactivity to behavioral stress in young, adult normotensive African-American females. A lifestyle change such as exercising may play a role in reducing the risk of hypertension in African-American women.

Racial differences in minimum lower leg vascular resistance in normotensive young adults with positive and negative parental histories of hypertension.

OBJECTIVE: To determine whether peripheral hemodynamic differences exist in young adult normotensive African Americans and white Americans with a positive and negative parental history of hypertension. METHODS: The participants were healthy men of whom 13 were African Americans and nine white Americans with a positive parental history and 19 were African Americans and 13 white Americans with a negative parental history. Lower leg blood flows were obtained at rest and during reactive hyperemia. Lower leg minimum vascular resistance (Rmin) was computed from reactive hyperemic blood flow measured by venous occlusion plethysmography, and mean arterial blood pressure was determined by auscultation of the brachial artery. RESULTS: Resting blood flow and mean arterial pressure were similar in all groups. A significant race x parental history interaction effect was observed for lower leg Rmin. In the white men the lower leg Rmin was significantly greater in the positive than the negative parental group (P < 0.05). Lower leg Rmin was significantly greater in African Americans than in white men without a parental histoy (P < 0.05). Mean arterial blood pressure and heart rate were similar among the groups. CONCLUSIONS: This study demonstrates that lower leg Rmin is greater in young white men with a positive parental history of hypertension than those with a negative parental history. In African Americans with either positive or negative parental histories, lower leg Rmin is not different. This finding suggests that heredity may have a greater influence in white populations than in African Americans on the structural changes in resistance vessels. The study also suggests that African Americans have an earlier structural change in the resistance vessels compared with white people, regardless of a parental history of hypertension. This suggests that factors other than heredity are of importance in changing the structure of the resistance vessels.

Lower leg high-intensity resistance training and peripheral hemodynamic adaptations.

High-intensity resistance (HIR) training has been associated with muscle hypertrophy and decreased microvascular density that might produce a blood flow limitation. The effect of HIR training on lower leg maximal blood flow and minimum vascular resistance (Rmin) during reactive hyperemia were investigated in 7 healthy males. The gastrocnemius-soleus muscles of one leg were trained using maximal isokinetic concentric contractions for 4 weeks; the nontrained leg was the control. Lower leg blood flow was measured by venous occlusion plethysmography. Lower leg muscle volume was determined using magnetic resonance imaging. Peak isokinetic torque increased in both the trained (T) and nontrained (NT) legs (p < .05). Lower leg muscle volume increased by 2% in the T leg only (p < .05). In the T leg, maximal blood flow decreased and Rmin increased (p < .05); no hemodynamic change was detected in the NT leg. It is concluded that HIR training of the calf muscles is associated with a decrease in hyperemia-induced blood flow; thereby, indicating a blood flow limitation to the calf muscles.

First ray joint limitation, pressure, and ulceration of the first metatarsal head in diabetes mellitus.

Measurements of first ray mobility, pressure, and other variables were made on 19 diabetic patients with a history of ulceration at the first metatarsal head, 20 diabetic patients with a history of ulceration at other locations of the forefoot, 19 matched diabetic controls, and 19 matched nondiabetic controls. Patients with a history of first metatarsal head ulceration had significantly less first ray mobility and significantly higher pressure at the first metatarsal head compared with the other groups. Regression analysis found a moderate inverse linear relationship between first ray dorsiflexion and peak pressure at the first metatarsal head (R2 = 0.46, P < .0001). Results showed that sensory loss, duration of diabetes, and limited range of motion at the hip, ankle, and foot were related to ulcerations at all forefoot locations, Limited first ray mobility and high pressure at the first metatarsal head were related to ulcerations only at the first metatarsal head location.

Exercise blood pressure response and skeletal muscle vasodilator capacity in normotensives with positive and negative family history of hypertension.

OBJECTIVE: To study exercise blood pressure response in association with exercising muscle maximal vasodilatory capacity in normotensives with a positive and negative family history of hypertension. SUBJECTS: Twenty-eight normotensive healthy subjects were recruited. Of these, two females and 13 males had a positive, and three females and 10 males had a negative, family history of hypertension. METHODS: Both groups of subjects rode a bicycle ergometer while systolic blood pressure, diastolic blood pressure and heart rate were measured at 30%, 60% and peak oxygen uptake rate. The vasodilatory capacity was examined in the lower leg by measuring the minimal vascular resistance during peak reactive hyperemia after 10 min arterial occlusion. RESULTS: Age, body weight, resting blood pressure, peak oxygen uptake rate and casual lower leg vascular resistance were not significantly different between the two groups of subjects. Significantly higher exercise systolic blood pressure (9%) and diastolic blood pressure (9%) were seen in the subjects with positive family history of hypertension compared with the subjects with negative family history of hypertension. Exercise heart rate was significantly higher in the subjects with negative than in those with positive family history of hypertension. The vascular resistance at peak vasodilation was 22% higher in the subjects with positive than in the subjects with negative family history of hypertension. CONCLUSIONS: This study demonstrates that the dynamic exercise blood pressure is exaggerated and skeletal muscle vasodilatory capacity is limited in normotensives with genetic risk of hypertension. This suggests that the higher pressor response to physical stress that is found in normotensives with a family history of hypertension may be attributed to the resistance vessels in the exercising muscle.

Effects of chromium picolinate on beginning weight training students.

Changes in body weight (BW), a sum of three body circumferences (sigma C), a sum of three skinfolds (sigma SF), and the one-repetition maximum (1RM) for the squat (SQ) and bench press (BP) were examined in 59 college-age students (37 males [M], 22 females [F]) over a 12-week weight lifting program. Using a double-blind protocol, half of the students were given 200 micrograms/day chromium (Cr) in the form of chromium picolinate (CrPic) while the other half received a placebo (P). Therefore four groups were randomly formed: F-CrPic (n = 12), F-P (n = 10), M-CrPic (n = 18), and M-P (n = 19). All groups had significant increases in sigma C and significant decreases in sigma SF. No treatment effects were seen for the strength measurements, although the males experienced greater absolute increases. The only significant treatment effect found was due to the F-CrPic group gaining more BW (p = 0.0048) than the other three groups. It was concluded that CrPic supplementation had a greater effect on the females than on the males.

Effects of types and intensities of background music on treadmill endurance.

The effects of different types of music on heart rate (HR), rating of perceived exertion (RPE), and time to exhaustion during treadmill work were determined on 24 volunteer college students (Ss). The Ss participated in three randomly assigned multistaged treadmill walk/run to exhaustion while wearing a head-set. The three treatments were: loud, fast, exciting, popular music (Type A); soft, slow, easy-listening, popular music (Type B); and no music (control). HR was recorded at 0:30 of each minute until voluntary exhaustion. RPE was obtained after the test for five different points during the test. Differences (p less than 0.10) among experimental treatments were determined by a one-way ANOVA and Newman-Keuls. HR was lower with Type B music in minutes one and six. The peak HR and the HR in the minute preceding max were higher with Type B music. Time to exhaustion was longer during the Type B music treatment than during the control treatment. RPE was lower for Type B music than control during moderate work. This study provided some support for the hypothesis that soft, slow music reduces physiological and psychological arousal during submaximal exercise and increases endurance performance.

The effects of static stretching and warm-up on prevention of delayed-onset muscle soreness.

It has been suggested in the lay literature that static stretching and/or warm-up will prevent the occurrence of Delayed-Onset Muscle Soreness (DOMS). The primary purpose of this study was to determine the effects of static stretching and/or warm-up on the level of pain associated with DOMS. Sixty-two healthy male and female volunteers were randomly assigned to four groups: (a) subjects who statically stretched the quadriceps muscle group before a step, (b) subjects who only performed a stepping warm-up, (c) subjects who both stretched and performed a stepping warm-up prior to a step test, and (d) subjects who only performed a step test. The step test (Asmussen, 1956) required subjects to do concentric work with their right leg and eccentric work with their left leg to voluntary exhaustion. Subjects rated their muscle soreness on a ratio scale from zero to six at 24-hour intervals for 5 days following the step test. A 4x2x2 ANOVA with repeated measures on legs and Duncan's New Multiple Range post-hoc test found no difference in peak muscle soreness among the groups doing the step test or for gender (p greater than .05). There was the expected significant difference in peak muscle soreness between eccentrically and concentrically worked legs, with the eccentrically worked leg experiencing greater muscle soreness. We concluded that static stretching and/or warm-up does not prevent DOMS resulting from exhaustive exercise.

Physiological and psychological responses to exercise with an induced attentional focus.

In this study techniques were employed to induce exercising subjects to focus attention on themselves or on an external event. A total of 20 adult subjects (10 men and 10 women) were familiarized with a treadmill exercise protocol and then on two subsequent occasions performed submaximal exercise followed by a run to exhaustion under attentional conditions of self-focus (watching themselves in a mirror while listening to their breathing) and external focus (watching and listening to a movie). The order of focus conditions was counterbalanced among subjects. Analysis of postexperimental responses from subjects indicated that the procedures used to induce each type of attentional focus were successful. However, physiological and psychological responses in the two focus conditions were not always uniform for men and women, particularly during light work when men tended to have higher heart rates and significantly lower Rated Perceived Exertion while women had lower heart rates and higher Rated Perceived Exertion under self-focused conditions than under externally focused conditions. Possible explanations for the incongruence of physiological and psychological responses of men and women to the two types of attentional focus are discussed.

Alcohol, cardiorespiratory function and work performance.

Twelve males (six moderate drinkers and six abstainers) were studied for the influence of varying dosages of alcohol on cardiorespiratory function and work performance. The subjects underwent three separate maximal exercise tests which consisted of progressive workloads on the bicycle ergometer. Prior to each work bout the subject consumed either a placebo (0.0 ml.kg-1), small (0.44 ml.kg-1), or a moderate (0.88 ml.kg-1) dose of a 95 per cent ethanol solution. Analysis of the results indicated that the ingestion of a small or moderate amount of alcohol had no significant effect on heart rate, blood pressure, ventilation, oxygen uptake or work performance.

Athletics and cardiovascular health.

The heart includes systolic and diastolic components. The immediate effects of physical activity include increased sympathetic nervous and related hormonal activity; increased heart rate, contractility, stroke volume, and cardiac output. The time for systole and diastole are reduced, with relatively more work per beat. Light activity prior to the following strenuous exertion enhances performance, safety, and recovery. Children, women, and men show similar responses to activity: acute stress, with long-term improvements in cardiovsacular function. There is no cardiovascular reason for restricting activity for children or women. Mental and/or emotional stressors cause similar stress reactions, without the potential long-range benefits of regular physical activity. Athletics is viewed as an optional part of a lifetime of regular, vigorous activity, and as such can make a contribution to one's cardiovascular fitness. From this viewpoint, there is no need to put one in the stressful athletic situation until adequate pre-conditioning has taken place. Neither is there a place for inactive promoters of athletics for its own sake.