The effect of interval sprinting exercise on vascular function and aerobic fitness of post-menopausal women.

Menopausal transition accelerates an age-associated decrease in vascular function and a decline in aerobic fitness. The purpose of this study was to examine the effect of 8 weeks of interval sprinting cycle ergometer exercise on arterial stiffness, basal forearm blood flow, and aerobic fitness of post-menopausal women. Sixty overweight post-menopausal women were randomized into either exercise (Ex, n = 30) or control (C, n = 30) groups. Ex participants completed 24 interval sprinting exercise (ISE) sessions over 8 weeks. Each 20-minute ISE session comprised of alternating 8 seconds sprints and 12 seconds of light pedaling. Arterial stiffness assessed through ankle-brachial pulse wave velocity (baPWV) and augmentation index (AIx), basal forearm blood flow (FBF) assessed using venous occlusion, and aerobic fitness were assessed before and after the intervention. baPWV was significantly decreased in the Ex group by 7.2%, P = .03, whereas AIx demonstrated a 10% decrease, P = .002. No changes were found in basal FBF. Aerobic fitness was significantly increased, P = .002, in the Ex group (14%) with no change occurring in the control group.ISE training, despite minimal exercise commitment time (8 hours over 8 weeks), significantly lowered the arterial stiffness and increased the aerobic fitness of post-menopausal women. These results suggest that ISE positively influences the negative change in arterial stiffness and aerobic fitness that typically accompanies menopause.

The Effect of Sprint Interval Training on Body Composition of Postmenopausal Women.

INTRODUCTION: Menopause is accompanied by body composition changes that include a decrease in lean mass and aerobic fitness and an increase in fat mass. Sprint interval training (SIT) may be able to reverse these changes. PURPOSE: To examine the effect of an 8-wk SIT program on body composition and aerobic fitness of overweight postmenopausal women. METHODS: Forty postmenopausal women were randomized into SIT (n = 20) or control (n = 20) groups. The SIT group completed three SIT sessions a week for 8 wk with each session consisting of 20 min of alternating 8-s sprints and 12-s of light pedaling. Total mass, regional lean mass, and fat mass were assessed using dual-energy x-ray absorptiometry. Maximal oxygen uptake (V˙O2max) was predicted using a submaximal test. RESULTS: Total lean mass was significantly increased from pretest (48.1 ± 5.81 kg) to posttest (48.8 ± 5.96 kg) and fat mass was significantly reduced (pre, 29.5 ± 7.29 kg; post, 29.1 ± 7.61 kg) for the SIT group. Lean mass was mostly increased in the trunk (pre, 24.4 ± 2.79 kg; post, 24.8 ± 2.93 kg) and legs (pre, 15.6 ± 2.31 kg; post, 15.9 ± 2.34 kg). V˙O2max was significantly increased from pretest (21.7 ± 4.89 mL⋅kg⋅min) to posttest (24.4 ± 5.96 mL⋅kg⋅min) for the SIT group only. CONCLUSIONS: The SIT intervention increased total lean mass, decreased fat mass, and increased aerobic fitness of postmenopausal women after only 8 h of actual exercise over 8 wk.

Cardiovascular response of postmenopausal women to 8 weeks of sprint interval training.

INTRODUCTION: Menopause is accompanied by decreased aerobic fitness and increased risk of cardiovascular disease. Sprint interval training (SIT) is a time-efficient intervention for improving cardiovascular function and aerobic fitness of young adults. AIM: To determine the effect of an 8-week SIT program on the cardiovascular function and aerobic fitness of overweight postmenopausal women. METHOD: Thirty overweight postmenopausal women were randomized into exercise (n = 15) or control (n = 15) groups. The intervention group completed three SIT sessions a week for 8 weeks. Each session consisted of 20 min of 8-s sprints and 12 s of light pedalling. Participants also completed 8 min of light aerobic cycle exercise, before and after the SIT intervention. Cardiovascular function including heart rate, stroke volume (SV), and diastolic filling time (DFT) was assessed before and after the intervention and during 8 min of light aerobic exercise. Estimated maximal oxygen uptake ([Formula: see text]) was also assessed. RESULTS: Resting SV was increased (p = 0.001) from pre- (77.5 ± 17.0 mL) to post-SIT (81.3 ± 17.0 mL), whereas SV during 8 min of light aerobic exercise was increased (p = 0.000), from pre- (97.8 ± 1.6 mL) to post-test (103.5 ± 17.8 mL). Resting DFT was increased, (p = 0.010), at pre- (333.4 ± 94.4 mL) to post-SIT (357.4 ± 88.2 mL), whereas DFT during 8 min of aerobic exercise was increased, (p = 0.000), from pre- (480.1 ± 99.5 mL) to posttest (527.2 ± 123.0 mL). Predicted [Formula: see text] was increased, (p = 0.016), from pre- (19.5 ± 5.87 mL kg-1 min-1) to post-SIT (21.4 ± 7.02 mL kg-1 min-1). CONCLUSION: SIT improved cardiovascular function and aerobic fitness of overweight postmenopausal women after 8 weeks of exercise.

The Effect of Green Tea Ingestion and Interval Sprinting Exercise on the Body Composition of Overweight Males: A Randomized Trial.

The combined effect of green tea ingestion and interval sprinting exercise on body and abdominal fat of overweight males was investigated. Participants were randomly assigned into control (C), green tea (GT), interval sprinting exercise (ISE), and green tea and ISE (GT + ISE) groups. The GT, GT + ISE, and C groups consumed three GT capsules daily. The ISE and GT + ISE groups completed 36 ISE sessions over 12 weeks. Forty eight overweight males with a mean BMI of 28.5 ± 0.92 kg/m² and age of 26 ± 0.7 years acted as participants. There was a significant reduction in total and abdominal fat mass for the ISE and GT + ISE groups, p < 0.05, however, total and abdominal fat mass did not significantly change in the GT and C groups. There was a significant increase in total lean mass, p < 0.05, after the intervention for the ISE and GT + ISE groups only. There was a significant increase in fat oxidation during submaximal aerobic exercise, p < 0.05, after the intervention for the ISE, GT + ISE, and GT groups with no change for the C group. Following the 12-week intervention the ISE and GT + ISE groups, compared to C, recorded a significantly greater decrease in body and abdominal fat, and a significant increase in total lean mass. Ingestion of green tea by itself, however, did not result in a significant decrease in body or abdominal fat, but increased fat utilization during submaximal exercise. The combination of 12 weeks of GT ingestion and ISE did not result in greater total and abdominal fat reduction compared to 12 weeks of ISE alone.

The combined effect of green tea and acute interval sprinting exercise on fat oxidation of trained and untrained males.

PURPOSE: This study investigated the combined effect of green tea and acute interval sprinting exercise on fat oxidation of trained and untrained males. METHODS: Fourteen trained and 14 untrained males ingested one capsule containing either green tea or cellulose with breakfast, lunch, and dinner, 24 hours before two exercise sessions. A fourth capsule was consumed 90 minutes before exercise after overnight NPO (nil per os). Participants performed a 20-minute interval sprinting cycling protocol, consisting of repeated bouts of 8-seconds of sprint cycling (at 65% of maximum power output) and 12-seconds of recovery (at 25% of maximum power output), followed by 75 minutes of post-exercise recovery. RESULTS: Fat oxidation was significantly greater in the resting condition after green tea ingestion (p < 0.05) compared with the placebo. Fat oxidation was also significantly increased post-exercise in the green tea, compared with the placebo condition (p < 0.01). During and after exercise the plasma glycerol levels significantly increased in both groups after green tea consumption and were significantly higher in the untrained group compared with the trained group (p < 0.05). Compared with the placebo, the plasma epinephrine levels were significantly higher for both groups in the green tea condition during and after exercise, however, norepinephrine levels were only significantly greater, p < 0.05, during and after exercise in the untrained group. CONCLUSION: Green tea significantly increased resting and post-exercise fat oxidation and also elevated plasma glycerol and epinephrine levels during and after interval sprinting. Glycerol and norepinephrine levels during interval sprinting were significantly higher in the untrained group compared with the trained group.

Effect of acute interval sprinting exercise on postprandial lipemia of sedentary young men.

PURPOSE: Postprandial lipemia (PPL) contributesto the development of atherosclerosis. In females, repeated 8-second bouts of interval sprinting exercise reduced PPL, however, the effect of 8-second bouts of interval sprinting on PPL of overweight males is undetermined. Thus, the effect of 8-secondsof interval sprinting for 20 min, the night before ingestion of a high-fat meal (HFM), on plasma triacylglycerol(TG) levelswas examined. METHODS: Ten overweight males acted as participants (BMI = 26±3.0kg/m2, age 22 ± 2.5 years). A crossover design was employed withinterval sprinting and a noexercise condition separated by 7days. Participants consumed a milkshake (high-fat meal;HFM = 4170 kJ/993 Kcal) the morning after an overnight fast, followed by 4 hourly blood samples. Participants performedone bout of interval sprinting (8seconds sprinting at 110-115rpm, 12seconds active recovery at ~60rpm for 20 minutes) the evening before the consumption of the HFM. RESULTS: Postprandial TG was 22.5% lower in the interval sprinting compared to the noexercise condition when comparing the change in total area under the curve (ΔAUCT): ISE(7.15±1.90mmolL(-1)h(-1)) versus noexercise (9.22±3.44mmolL(-1)h(-1)), p=.014. The correlation between fasting TG levels in the noexercise condition and total reduction in AUCT between the conditions was significant (r=.87, p=.001). CONCLUSION: One 20-min bout of interval sprinting,the night before consumption of a HFM,significantly attenuated the PPL response of sedentary males.

Green Tea, Intermittent Sprinting Exercise, and Fat Oxidation.

Fat oxidation has been shown to increase after short term green tea extract (GTE) ingestion and after one bout of intermittent sprinting exercise (ISE). Whether combining the two will result in greater fat oxidation after ISE is undetermined. The aim of the current study was to investigate the combined effect of short term GTE and a single session of ISE upon post-exercise fat oxidation. Fourteen women consumed three GTE or placebo capsules the day before and one capsule 90 min before a 20-min ISE cycling protocol followed by 1 h of resting recovery. Fat oxidation was calculated using indirect calorimetry. There was a significant increase in fat oxidation post-exercise compared to at rest in the placebo condition (p < 0.01). After GTE ingestion, however, at rest and post-exercise, fat oxidation was significantly greater (p < 0.05) than that after placebo. Plasma glycerol levels at rest and 15 min during post-exercise were significantly higher (p < 0.05) after GTE consumption compared to placebo. Compared to placebo, plasma catecholamines increased significantly after GTE consumption and 20 min after ISE (p < 0.05). Acute GTE ingestion significantly increased fat oxidation under resting and post-exercise conditions when compared to placebo.

Effect of high-intensity intermittent exercise on postprandial plasma triacylglycerol in sedentary young women.

High-intensity intermittent exercise (HIIE) such as the 30-s Wingate test attenuates postprandial triacylglycerol (TG), however, the ability of shorter versions of HIIE to reduce postprandial TG is undetermined. Thus, the effect of 8-s sprinting bouts of HIIE on blood TG levels of 12 females after consumption of a high-fat meal (HFM) was examined. Twelve young, sedentary women (BMI 25.1 ± 2.3 kg/m²; age 21.3 ± 2.1 years) completed a maximal oxygen uptake test and then on different days underwent either an exercise or a no-exercise postprandial TG condition. Both conditions involved consuming a HFM after a 12-hr fast. The HFM, in milkshake form provided 4170 kJ (993 Kcal) of energy and 98 g fat. Order was counter-balanced. In the exercise condition participants completed 20-min of HIIE cycling consisting of repeated bouts of 8 s sprint cycling (100-115 rpm) and 12 s of active rest (easy pedaling) 14 hr before consuming the HFM. Blood samples were collected hourly after the HFM for 4 hr. Total postprandial TG was 13% lower, p = .004, in the exercise (5.84 ± 1.08 mmol L⁻¹ 4 h⁻¹) compared with the no-exercise condition (6.71 ± 1.63 mmol L⁻¹ 4 h⁻¹). In conclusion, HIIE significantly attenuated postprandial TG in sedentary young women.

The relationship between cardiac autonomic function and maximal oxygen uptake response to high-intensity intermittent-exercise training.

Major individual differences in the maximal oxygen uptake response to aerobic training have been documented. Vagal influence on the heart has been shown to contribute to changes in aerobic fitness. Whether vagal influence on the heart also predicts maximal oxygen uptake response to interval-sprinting training, however, is undetermined. Thus, the relationship between baseline vagal activity and the maximal oxygen uptake response to interval-sprinting training was examined. Exercisers (n = 16) exercised three times a week for 12 weeks, whereas controls did no exercise (n = 16). Interval-sprinting consisted of 20 min of intermittent sprinting on a cycle ergometer (8 s sprint, 12 s recovery). Maximal oxygen uptake was assessed using open-circuit spirometry. Vagal influence was assessed through frequency analysis of heart rate variability. Participants were aged 22 ± 4.5 years and had a body mass of 72.7 ± 18.9 kg, a body mass index of 26.9 ± 3.9 kg · m(-2), and a maximal oxygen uptake of 28 ± 7.4 ml · kg(-1) · min(-1). Overall increase in maximal oxygen uptake after the training programme, despite being anaerobic in nature, was 19 ± 1.2%. Change in maximal oxygen uptake was correlated with initial baseline heart rate variability high-frequency power in normalised units (r = 0.58; P < 0.05). Thus, cardiac vagal modulation of heart rate was associated with the aerobic training response after 12 weeks of high-intensity intermittent-exercise. The mechanisms underlying the relationship between the aerobic training response and resting heart rate variability need to be established before practical implications can be identified.

High-intensity intermittent exercise and cardiovascular and autonomic function.

OBJECTIVE: The effect of 12 weeks of high-intensity intermittent exercise (HIIE) on cardiac, vascular, and autonomic function of young males was examined. METHODS: Thirty-eight young men with a BMI of 28.7 ± 3.1 kg m(-2) and age 24.9 ± 4.3 years were randomly assigned to either an HIIE or control group. The exercise group underwent HIIE three times per week, 20 min per session, for 12 weeks. Aerobic power and a range of cardiac, vascular, and autonomic measures were recorded before and after the exercise intervention. RESULTS: The exercise, compared to the control group, recorded a significant reduction in heart rate accompanied by an increase in stroke volume. For the exercise group forearm vasodilatory capacity was significantly enhanced, P < 0.05. Arterial stiffness, determined by pulse wave velocity and augmentation index, was also significantly improved, after the 12-week intervention. For the exercise group, heart period variability (low- and high-frequency power) and baroreceptor sensitivity were significantly increased. CONCLUSION: High-intensity intermittent exercise induced significant cardiac, vascular, and autonomic improvements after 12 weeks of training.

The effects of high-intensity intermittent exercise training on cardiovascular response to mental and physical challenge.

The purpose was to examine the effect of a 12-week exercise intervention on the cardiovascular and autonomic response of males to mental and physical challenge. Thirty four young overweight males were randomly assigned to either an exercise or control group. The exercise group completed a high-intensity intermittent exercise (HIIE) program three times per week for 12weeks. Cardiovascular response to the Stroop task was determined before and after the intervention by assessing heart rate (HR), stroke volume (SV), arterial stiffness, baroreflex sensitivity (BRS), and skeletal muscle blood flow. The exercise group improved their aerobic fitness levels by 17% and reduced their body weight by 1.6kg. Exercisers compared to controls experienced a significant reduction in HR (p<0.001) and a significant increase in SV (p<0.001) at rest and during Stroop and exercise. For exercisers, arterial stiffness significantly decreased at rest and during Stroop (p<0.01), whereas BRS was increased at rest and during Stroop (p<0.01). Forearm blood flow was significantly increased during the first two minutes of Stroop (p<0.05). HIIE induced significant cardiovascular and autonomic changes at rest and during mental and physical challenge after 12weeks of training.

Vascular and baroreceptor abnormalities in young males with a family history of hypertension.

Vascular and baroreceptor abnormalities in 44 young males, mean age 21 years, comprising of offspring with (FH(+); n = 22) and without (FH(-); n = 22) hypertensive parents, were investigated. Peak forearm blood flow (FBF), which was defined as the highest blood flow obtained following reactive hyperaemia, was assessed using strain gauge plethysmography following 5 min of ischemia. Cardiopulmonary baroreceptor sensitivity was assessed using lower body negative pressure for 5 min at -20 mmHg and was determined by calculating change of stroke volume and forearm vascular resistance (FVR) to lower body negative pressure. Carotid baroreceptor sensitivity was assessed using neck suction at -20, -40, -60, and -80 mmHg and was calculated by dividing RR interval by systolic blood pressure. Augmentation index, a measure of wave reflection, was assessed using applanation tonometry and was calculated as the ratio of augmented pressure and pulse pressure. Peak FBF of FH(+) was 19% lower than the FH(-) (p = 0.02). Also FH(+) had 17% higher peak FVR compared to FH(-) (p = 0.04). However, there were no significant differences between groups for cardiopulmonary, carotid baroreceptor sensitivity, and augmentation index. These results suggest that peripheral vascular dysfunction appears earlier than abnormal baroreceptor sensitivity in young males with a family history of hypertension.

Fatness is related to blunted vascular stress responsivity, independent of cardiorespiratory fitness in normal and overweight men.

Obesity is associated with disturbed cardiovascular responsivity to mental stress, which may mediate psychosocial disease pathways. Whether being aerobically fit is protective against psychophysiological dysfunction in the presence of overweight or obesity is undetermined. Peripheral blood flow, blood pressure, and cardiac responses were measured during a 2-min mental stress task in 48 healthy men (aged 18-32 years). Mental stress-evoked increases in mean arterial pressure and heart rate, forearm vasodilatation, and cardiac parasympathetic withdrawal. Multiple linear regression analyses adjusted for age, peak oxygen uptake, and baseline forearm vascular resistance, revealed that greater fatness was related to a blunted vasodilatation response to mental stress (beta=-.31, p<.05). There were no interactive effects of fitness and fatness. Fitness does not appear to moderate the association between fatness and impaired vascular stress responsivity in normal and overweight men.

Reproducibility of skeletal muscle vasodilatation responses to Stroop mental challenge over repeated sessions.

Skeletal muscle blood flow responses to stress have implications for psychobiological disease pathways. An important assumption underlying psychophysiological studies relating stress reactivity with disease risk is that individuals are characterized by stable response profiles that can be reliably assessed using acute psychophysiological stress testing. We examined the reproducibility of forearm vasodilatation, blood pressure, and cardiac responses to a 2 min Stroop mental challenge over two repeated stress sessions that were on average 3.6 months apart. Participants were 21 healthy men and women (aged 21.8+/-3.7 years). Vasodilatation, blood pressure and heart rate responses displayed no habituation between sessions, although there was significantly greater cardiac parasympathetic involvement during the second testing session. Significant test-retest correlations between the sessions were observed for both forearm blood flow and heart rate reactivity. These findings demonstrate skeletal muscle vasodilatation responses to repeated stress are robust, so may be a useful psychophysiological indicator in studies of stress reactivity and disease risk.

Cardiovascular response to Stroop: effect of verbal response and task difficulty.

The purpose was to examine the effect of verbal response and task difficulty on cardiovascular response to the Stroop task. Heart rate, mean arterial blood pressure, forearm blood flow (FBF), and catecholamine response of 13 males was assessed during 3, 5-min differing versions of the Stroop task. Heart rate, epinephrine, and FBF were significantly greater during Stroop 1 (the color-word conflict task) compared to Stroop 3 (a non-verbal version of Stroop where participants responded cognitively without any oral or behavioural response), whereas mean arterial pressure was significantly greater during Stroop 1 than that of Stroop 2 (slides in monochrome without color conflict) and Stroop 3. Rating of level of difficulty and concentration was lower for Stroop 2 compared to the other two Stroop tasks. These results suggest that performance of the traditional Stroop task caused significant cardiovascular, FBF, and epinephrine reactivity. This reactivity was attenuated during reading of monochrome words and was virtually abolished when performing the Stroop without verbally responding.

Limb vasodilatory capacity and venous capacitance of trained runners and untrained males.

Aerobically trained athletes possess enhanced vasodilatory capacity and venous capacitance in their exercising muscles. However, whether they also possess these characteristics in their non-specific exercising muscles is undetermined. This study examined vasodilatory capacity and venous capacitance of specific (legs) and non-specific exercising muscles (arms) of ten trained runners and ten active but untrained males aged 18-35 years. Venous occlusion plethysmography determined baseline and peak blood flow after 5 min of reactive hyperaemia. Forearm and leg venous capacitance were determined as the difference between baseline and 2 min of venous occlusion at 50 mmHg. During reactive hyperaemia, trained runners had higher leg (48.4+/-5.3 ml.100 ml tissue(-1).min(-1)) and arm (40.8+/-2.1 ml.100 ml tissue(-1).min(-1)) vasodilatory capacity compared to the untrained (leg: 37.3+/-2.5 ml.100 ml tissue(-1).min(-1); arm: 34.2+/-2.2 ml.100 ml tissue(-1).min(-1); P<0.05), and higher calf vascular conductance (0.51+/-0.06 ml.100 ml tissue(-1).min(-1).mmHg(-1) versus 0.35+/-0.03 ml.100 ml tissue(-1).min(-1).mmHg(-1); P<0.05). The trained also had higher venous capacitance in both arms (3.5+/-0.2 ml 100.ml(-1)) and legs (4.8+/-0.1 ml.100 ml(-1)) compared to the untrained (3.0+/-0.2 ml 100.ml(-1); 4.2+/-0.2 ml.100 ml(-1); P<0.05). These findings show that vasculature adaptations to running occur in both specific and non-specific exercising muscles.

Effect of pedal rate and power output on rating of perceived exertion during cycle ergometry exercise.

This study examined differentiated rating of perceived exertion (RPE), heart rate, and heart-rate variability during light cycle ergometry exercise at two different pedal rates. 30 healthy men (22.6 +/- 0.9 yr.) were recruited from a student population and completed a continuous 20-min. cycle ergometry exercise protocol, consisting of a 4-min. warm-up (60 rev./min., 30 Watts), followed by four bouts of 4 min. at different combinations of pedal rate (40 or 80 rev./min.) and power output (40 or 80 Watts). The order of the four combinations was counterbalanced across participants. Heart rate was measured using a polar heart-rate monitor, and parasympathetic balance was assessed through time series analysis of heart-rate variability. Measures were compared using a 2 (pedal rate) x 2 (power output) repeated-measures analysis of variance. RPE was significantly greater (p<.05) at 80 versus 40 rev./min. at 40 W. For both power outputs heart rate was significantly increased, and the high frequency component of heart-rate variability was significantly reduced at 80 compared with 40 rev./min. These findings indicate the RPE was greater at higher than at lower pedalling rates for a light absolute power output which contrasts with previous findings based on use of higher power output. Also, pedal rate had a significant effect on heart rate and heart-rate variability at constant power output.

The role of cardiopulmonary baroreceptors during the forearm vasodilatation response to mental stress.

The forearm vasodilatation response to mental stress in humans is thought to be mediated by sympathetic withdrawal and beta-adrenergic mechanisms. However, the mechanisms of altered neural control during sympathetic withdrawal are unclear. Thus, cardiopulmonary baroreceptor activity in relation to sympathetic withdrawal during mental stress was examined. Forearm blood flow was measured during mental stress in males (n = 18) during control and lower body negative pressure at -20 mmHg. Forearm blood flow was significantly increased during mental challenge; however, during lower body negative pressure the vasodilatation response was significantly attenuated in comparison with control. The results suggest the cardiopulmonary baroreceptors are involved with the sympathetic withdrawal response during forearm vasodilatation to mental stress.

Stroke volume response to incremental submaximal exercise in aerobically trained, active, and sedentary men.

Stroke volume response of trained cyclists (n = 10; Trained), active but untrained men (n = 10; Active), and sedentary men (n = 10; Sedentary) was determined by impedance cardiography during cycle ergometer exercise. For the Trained, at a heart rate of 90 beats. min(-1), stroke volume increased by 27% compared to baseline levels, whereas stroke volume of Active and Sedentary groups did not significantly increase. Throughout exercise indices of ventricular emptying and filling of Trained were significantly greater than that of the other two groups whereas ventricular rates of the Active were significantly greater than those of the Sedentary. Throughout exercise cardiac contractility of the Trained was significantly greater than the other two groups. Results indicate that despite similar resting heart rate, stroke volume, and body mass, Trained compared to Active men significantly enhanced stroke volume, ventricular filling, and cardiac contractility during incremental ergometry exercise. Active compared to Sedentary men, however, displayed significantly larger stroke volume and ventricular filling rates during ergometry. We conclude that impedance cardiography indices of ventricular performance of aerobically trained men were superior to those of active, untrained men possessing similar resting stroke volume and heart rate. Furthermore, the ventricular performance of the active men possessing large resting stroke volume was superior to that of sedentary men.