Aging is associated with arterial remodeling and dysfunction which predispose older adults to increased risk for cardiovascular disease (CVD). Although aerobic exercise training is associated with decreased risk for CVD, the optimal exercise training regimen to induce vascular adaptations in older adults is unknown. In older adults, there is some evidence that aerobic exercise improves vascular function in the exercising limbs, but not in the non‐exercising limbs, suggesting that all‐extremity exercise might be advantageous in the aged population. The purpose of this study was to compare, in older adults, the effect of all‐extremity high‐intensity interval training (HIIT) vs. moderate‐intensity continuous training (MICT) on arterial structure and function in the exercising arms and legs. Thirty‐six sedentary adults (55 to 76 yrs of age, 64±1 yrs; mean±SE), free of major clinical disease, were randomized to HIIT (n=13), MICT (n=12), or non‐exercise control group (CONT; n=11). HIIT and MICT were performed on a non‐weight‐bearing all‐extremity ergometer (Airdyne, Schwinn) on 4 days/week for 8 weeks under supervision. HIIT consisted of 40 min of 4×4 min intervals at 90% of peak heart rate (HRpeak) interspersed by 3 min bouts at 70% of HRpeak, while MICT consisted of 47 min at 70% of HRpeak. At pre‐ and post‐intervention, limb pulse wave velocity (PWV) was assessed in the arm (brachial to radial artery) and leg (femoral to posterior tibial artery; Doppler flowmeters), and arterial compliance (ultrasonography and applanation tonometry), intima‐medial thickness (IMT; ultrasonography) and blood flow (Doppler) were assessed at the brachial and common femoral arteries. Blood flow significantly increased after HIIT, but not MICT, in the femoral artery (HIIT: 546.5±58.4 vs. 769.2±88.8 ml/min, P<0.01; MICT: 669.1±48.9 vs. 733.6±44.4 ml/min, CONT: 683.7±95.7 vs. 703.3±76 ml/min, P≥0.3; pre‐ vs. post‐intervention) while in the brachial artery blood flow remained unchanged (HIIT: 112.3±16.8 vs. 105.8±13.6 ml/min, MICT: 127.1±18.2 vs. 108.7±14.3 ml/min, CONT: 109.3±17.3 vs. 114.5±22.3 ml/min, P≥0.2). Arm and leg PWV, and brachial and femoral artery compliance and IMT were not influenced by the intervention (P≥0.9). In conclusion, 8 weeks of all‐extremity HIIT, but not MICT, improved femoral, but not brachial, blood flow in previously sedentary older adults.
Type 2 diabetes (T2D) is associated with arterial remodeling and dysfunction which increase the risk for cardiovascular disease (CVD). There is some evidence that aerobic exercise induces arterial adaptations in the exercising limbs, but not in the non‐exercising limbs, suggesting that all‐extremity exercise might be advantageous. However, the optimal exercise training regimen to induce peripheral arterial adaptations in individuals with T2D is unknown. Therefore, the purpose of this study was to compare, in T2D patients, the effects of all‐extremity high‐intensity interval training (HIIT) vs. moderate‐intensity continuous training (MICT) on arterial structure and function in the exercising arms and legs. Thirty‐three sedentary T2D patients (46 to 78 yrs of age; 64 ± 1 yrs; means ± SE), free of CVD, were randomized to HIIT (n = 12), MICT (n = 10), or non‐exercise control group (CONT; n = 11). HIIT and isocaloric MICT were performed on a non‐weight‐bearing all‐extremity ergometer (Airdyne, Schwinn), 4 days/week for 8 weeks under supervision. HIIT consisted of 4×4‐min bouts at 90% of peak heart rate (HRpeak) interspersed by 3‐min bouts at 70% of HRpeak, while MICT consisted of 32 min at 70% of HRpeak. Both HIIT and MICT were preceded by a 10‐min warm‐up and followed by a 5‐min cool‐down at 70% of HRpeak. Arterial diameter (ultrasonography), intima‐medial thickness (IMT; ultrasonography), blood flow (Doppler) and arterial compliance (change in diameter and change in pressure) were assessed at the brachial (arm) and common femoral (leg) arteries at pre‐ and post‐intervention. Following the 8‐week exercise intervention, brachial and femoral diameter, IMT, blood flow and compliance did not significantly change in response to HIIT or MICT (P≥0.1 for group × time interaction). In conclusion, 8 weeks of all‐extremity HIIT and MICT do not lead to arterial remodeling or changes in arterial function in the exercising arms and legs in patients with T2D. Support or Funding Information This work was supported by National Institute of Aging grant AG050203 to DDC. This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .
Coffee is widely consumed and several studies have examined the acute effects of coffee consumption on blood pressure. However, little attention has focused on the acute effects of coffee on central arterial stiffness, wave reflection, and aortic blood pressure, independent predictors of cardiovascular disease. The objective of this investigation was to conduct a randomized, placebo‐controlled study of the acute effects of coffee on central arterial stiffness and hemodynamics. Sixteen young males (21±2 yrs; means±SE) who were light caffeine users consumed 16 oz. of cold coffee, containing 160 mg caffeine, or placebo (cold water) on two visits separated by at least a week. Central arterial stiffness (carotid to femoral pulse wave velocity; cfPWV), aortic wave reflection (augmentation index normalized at heart rate 75; AIx75) and aortic blood pressures (systolic, diastolic and mean blood pressure; aoSBP, aoDBP, aoMAP and pulse pressure; aoPP) were assessed using SphygmoCor XCEL (AtCor Medical) before and 1hr and 2hr after beverage consumption. In response to coffee, cfPWV increased at 1hr and remained elevated at 2hr (6.29±0.16 vs. 6.48±0.17 vs. 6.53±0.15 m/sec; P=0.03 for base vs. 1hr and P=0.004 for base vs. 2hr), but did not change in response to placebo (6.48±0.13 vs. 6.41±0.16 vs. 6.37±0.19 m/sec; P>0.5 for base vs. 1hr vs. 2hr and P=0.01 for condition × time). AIx75 decreased at 1hr and remained decreased at 2hr following coffee (5.5±2.9 vs. −2.4±3.1 vs. −1.7±3.3 %; P=0.0002 for base vs. 1hr and P=0.008 for base vs. 2hr) and placebo (3.9±2.8 vs. ‐ 3.7±2.5 vs. −6.7±2.6 %; P<0.0001 for base vs. 1hr and for base vs. 2hr), but to a different degree (P=0.015 for condition × time). AoSBP and aoPP were not affected by coffee or placebo (P>0.05). However, aoDBP and aoMAP increased in response to coffee by 7±2 and 5±1 mmHg, respectively, at 1hr and remained elevated at 2hr (aoDBP: 67±1 vs. 74±1 vs. 72±2 mmHg; P=0.002 for base vs. 1hr and P=0.03 for base vs. 2hr, aoMAP: 80±1 vs. 85±1 vs. 84±2 mmHg; P=0.003 for base vs. 1hr and P=0.04 for base vs. 2hr), but did not change following placebo (P>0.9 and P≥0.001 for condition × time). In conclusion, consumption of coffee containing 160 mg caffeine leads to acute changes in central arterial stiffness and hemodynamics in healthy young men. Future investigations should confirm these findings in women and examine whether responses are exaggerated in individuals who are hypertensive or have other cardiovascular disease risk factors. Support or Funding Information This work was supported by the Gatorade Trust through funds distributed by the University of Florida, Department of Medicine.
There is growing evidence of sex differences in the chronic effect of aerobic exercise on endothelial function (flow-mediated dilation; FMD) in older adults. However, whether sex differences also exist in the acute effect of aerobic exercise on FMD in older adults is unknown. PURPOSE: To test the hypothesis that the FMD response to acute aerobic exercise will be different in older men compared with postmenopausal women and that exercise intensity will influence the FMD response. METHODS: Thirteen older men and fifteen postmenopausal women, free of major clinical disease, participated in this randomized crossover study (67±1 vs. 65±2 yrs, mean±SE, P=0.4). Subjects completed a single bout of low-intensity continuous training (LICT; 47 min 50% peak heart rate (HRpeak)), moderate-intensity continuous training (MICT; 47 min 70% HRpeak) and high-intensity interval training (HIIT; 40 min: alternating intensities of 90% and 70% HRpeak) on the treadmill in a counterbalanced order. Brachial artery FMD was assessed at rest, at end of exercise and following 60-minute recovery. RESULTS: In older men, FMD was attenuated by 45% following HIIT (5.95±0.85 vs. 3.27±0.52%, P=0.003) and by 37% following MICT (5.97±0.87 vs. 3.73±0.47%, P=0.03; P=0.9 for FMD response to HIIT vs. MICT) and was normalized following 60-min recovery (P=0.99). In postmenopausal women, FMD did not significantly change in response to HIIT (4.93±0.55 vs. 6.31±0.57%, P=0.14) and MICT (5.32±0.62 vs. 5.60±0.68%, P=0.99). In response to LICT, FMD did not change in postmenopausal women nor older men (5.21±0.64 vs. 6.02±0.73%, P=0.7 and 5.70±0.80 vs. 5.55±0.67%, P=0.99). CONCLUSIONS: Sex and exercise intensity significantly impact the FMD response to acute aerobic exercise in older adults. In older men, FMD is attenuated following acute HIIT and MICT but not LICT, whereas in postmenopausal women FMD is unaffected.
High‐intensity interval training (HIIT) on the treadmill has been reported to be more effective in improving aerobic fitness and cardiac function compared with moderate‐intensity continuous training (MICT) in adults with cardiometabolic disorders. However, middle‐aged and older adults with type 2 diabetes (T2D) are often unable to tolerate weight‐bearing exercise which may hinder HIIT and MICT on the treadmill. Therefore, the purpose of this randomized clinical trial was twofold: 1) to test if non‐weight bearing all‐extremity HIIT and MICT are feasible in adults with T2D aged 50 to 79 yrs; and 2) to test whether HIIT is more effective in improving aerobic fitness and cardiac function than MICT. Fifty‐three sedentary adults with T2D (age: 63±1 yrs), free of cardiovascular disease, were randomized to HIIT (n=21), MICT (n=18) or non‐exercise control (CONT; n=14). HIIT (4×4‐min intervals at 90% of peak heart rate; HR peak ) and isocaloric MICT (70% of HR peak ) were performed on an all‐extremity ergometer, 4 times/week for 8 weeks under supervision. Aerobic fitness was assessed by oxygen consumption during an incremental maximal exercise test. Left ventricular (LV) function was assessed during rest by two‐dimensional echocardiography including conventional and tissue Doppler. All measures were obtained at pre‐ and post‐intervention. Approximately 80% of participants randomized to all‐extremity HIIT and MICT completed the exercise intervention. Aerobic fitness improved by 11% in HIIT (22.4±1.2 vs. 24.9±1.4 ml/kg/min, pre‐ vs. post‐intervention; P<0.0001) and 7% in MICT (21.4±1.3 vs. 23.0±1.3 ml/kg/min; P=0.004 and P=0.4 for HIIT vs. MICT), whereas it did not change in CONT (21.4±1.5 vs. 21.3±1.2 ml/kg/min; P=0.9). Ejection fraction, a measure of LV systolic function, increased in both HIIT and MICT by ~2% (HIIT: 54.7±0.7 vs. 56.6±0.9%; P=0.007 and MICT: 54.6±1.4 vs. 56.4±1.2%; P=0.04), whereas it remained unchanged in CONT (56.0±1.2 vs. 54.9±1.1%; P=0.2). Diastolic function was not significantly affected by the intervention (P≥0.06). In conclusion, all‐extremity HIIT and MICT are feasible in middle‐aged and older adults with T2D and are equally effective in improving aerobic fitness and LV systolic function. Support or Funding Information This work was supported by the National Institutes of Health (NIA AG 050203). This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .
Arterial stiffness and wave reflection are associated with increased risk for cardiovascular disease (CVD), while aerobic exercise is known to decrease CVD risk. The effects of chronic aerobic exercise training on arterial stiffness and wave reflection have been extensively studied, but data on the acute effects of aerobic exercise on these measures are primarily based on men and are limited and conflicting. The purpose of this study was to examine the sex‐specific acute vascular responses to high‐intensity interval training (HIIT), moderate‐intensity continuous training (MICT) and low‐intensity continuous training (LICT) in young adults. Thirty healthy adults, 15 young men and 15 premenopausal women (21.5±0.4 vs. 21.4±0.7 years of age, means ± SE, P =0.9) participated in this randomized crossover study. The SphygmoCor Xcel device (AtCor medical) was employed to assess arterial stiffness using carotid to femoral pulse wave velocity (cfPWV) and wave reflection using augmentation index (AIx). Measures of cfPWV and AIx were obtained prior to exercise (PreE), following the end of a single bout of HIIT, MICT and LICT on the treadmill (PostE), and following recovery from exercise. HIIT consisted of 4 × 4‐min intervals at 90% peak heart rate (HRpeak) interspersed by recovery bouts at 70% HRpeak for a total of 40 min, whereas MICT and LICT consisted of 47 min at 70% and 50% HRpeak, respectively. cfPWV remained unchanged in response to a single bout of exercise, regardless of exercise intensity or sex (5.5±0.1 vs. 5.5±0.1 vs. 5.4±0.1 m/s, PreE vs. PostE vs. recovery; P=0.2 for main effect of time). AIx decreased following recovery compared with PreE and PostE (P≤0.003), but this response was not influenced by exercise intensity or sex (10.3±1.7 vs. 9.0±1.7 vs. 5.0±1.5 %, PreE vs. PostE vs. recovery; P<0.0001 for main effect of time; P=0.8 for sex × exercise × time). In conclusion, exercise intensity and sex do not modulate central arterial stiffness and wave reflection following a single bout of aerobic exercise. Central arterial stiffness is unaffected by acute exercise, whereas wave reflection decreases following recovery from exercise. This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .
Endothelial function and central arterial stiffness are independent predictors of future cardiovascular events. High‐intensity interval training (HIIT) is a popular and oftentimes superior exercise strategy for decreasing cardiovascular disease risk than moderate‐intensity continuous training (MICT). We have recently adapted HIIT on a non‐weight‐bearing all‐extremity ergometer to reduce impact on the joints and involve muscles in the whole body to activate a larger amount of muscle mass than in lower‐extremity HIIT. However, the acute vascular responses to all‐extremity HIIT and MICT remain unexplored and may be important for optimizing exercise prescription. Therefore, the purpose of this study was to investigate the acute effects of all‐extremity HIIT and MICT on endothelial function, central arterial stiffness and hemodynamics. Sixteen young men (21±1 years of age, means±SE) who were free of clinical disease and did not use tobacco products or medications participated in this study. Vascular measures were assessed at pre‐exercise, at the end of a single session of HIIT and MICT and following recovery. HIIT and MICT were matched for caloric expenditure and were performed on an all‐extremity non‐weight‐bearing ergometer, at least one week apart. HIIT consisted of 4×4‐min intervals at 90% peak heart rate (HR peak ) interspersed by 3‐min intervals at 70% HR peak for a total of 40 min. MICT consisted of 47 min at 70% HR peak . Endothelial function was assessed using brachial artery flow‐mediated dilation (FMD) via high resolution ultrasonography in response to 5 min forearm blood flow occlusion. Arterial stiffness (carotid to femoral pulse wave velocity; cfPWV), aortic wave reflection (augmentation index normalized at heart rate 75; AIx75) and aortic systolic and diastolic blood pressure (aoSBP and aoDBP) were assessed using a validated cuff‐based device. HIIT did not result in significant changes in FMD (P=0.08), cfPWV (P=0.3), aoSBP (P=0.1) or aoDBP (P=0.2) within one hour from exercise cessation. AIx75 and heart rate were increased at the end of HIIT and remained elevated following recovery (P≤0.002 vs. pre‐exercise). In response to MICT, FMD remained unchanged (P=0.1). However, cfPWV decreased at the end of MICT (P=0.003) and returned to the pre‐exercise level following recovery (P=0.5). AIx75 increased at the end of MICT (P<0.0001) and returned to the pre‐exercise level following recovery (P=0.3). aoSBP decreased following recovery compared with end of MICT (P=0.04), but was not different than the pre‐exercise level (P=0.3). aoDBP did not significantly change in response to MICT (P=0.09). In conclusion, all‐extremity HIIT and MICT did not attenuate endothelial function or result in adverse changes in aortic blood pressure. MICT, but not HIIT, slightly reduced central arterial stiffness. These findings may have important implications for exercise prescription.
Brachial artery flow‐mediated dilation (FMD), a measure of endothelial function, is an independent predictor of future cardiovascular events. Sex and exercise intensity influence the acute FMD response to aerobic exercise in older adults, but in young adults this has not been investigated. Therefore, the purpose of this study was to compare the acute FMD response to a single bout of high‐intensity interval training (HIIT), moderate‐intensity continuous training (MICT) and low‐intensity continuous training (LICT) in young men vs. women. Twenty‐eight healthy young adults (14 men and 14 premenopausal women, 21.2±0.3 vs. 21.5±0.8 years of age, means ± SE, P =0.7) participated in this randomized crossover study. Brachial artery FMD was measured in response to reactive hyperemia following 5‐min forearm occlusion using high resolution ultrasonography. FMD measures were obtained prior to exercise, at the end of a single bout of HIIT (40 min, 4 × 4‐min intervals at 90% peak heart rate (HR peak ), MICT (47 min, 70% HR peak ) and LICT (47 min, 50% HR peak ) on the treadmill and following 60‐min recovery from exercise. The acute FMD response was influenced by exercise intensity but not sex (P=0.006 for exercise intensity × time and P=0.9 for sex × exercise intensity × time), thus the results are presented for men and women combined. FMD was attenuated by 20.7% following the end of HIIT (6.96±0.51 vs. 5.47±0.48%, pre‐ vs. end of exercise; P=0.001) and returned to pre‐exercise levels following 60‐min recovery (P>0.99). However, FMD did not change in response to MICT(7.10±0.53 vs. 6.32±0.57 vs. 7.26±0.37%; P≥0.3) and LICT (7.14±0.41 vs. 7.46±0.56 vs. 7.15±0.43%; P>0.99). In conclusion, exercise intensity, but not sex, significantly impacts the acute FMD response to aerobic exercise in young adults. This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .
Caffeine is widely consumed daily as a stimulant, ergogenic aid or performance enhancer. In addition to the traditional forms of caffeine consumption (e.g., coffee, tea and caffeinated soft drinks), alternative sources are becoming increasingly popular such as caffeinated tablets/capsules and gum. Caffeinated chewing gum offers rapid caffeine absorption and is commercially available. Although the acute cardiovascular effects of caffeine consumption from traditional sources are well documented, the effects of caffeinated chewing gum are unknown. Therefore, this double‐blinded, randomized, placebo‐controlled, crossover study sought to investigate the acute effects of caffeinated chewing gum on central arterial stiffness and aortic blood pressure, independent predictors of cardiovascular disease. Sixteen young (21±1 yrs, means±SE), male, light caffeine users, free of clinical disease, who did not use tobacco products, or medications participated in this study. Central arterial stiffness (carotid to femoral pulse wave velocity; cfPWV) and aortic blood pressures (systolic and diastolic blood pressure; aoSBP and aoDBP, and pulse pressure; aoPP) were assessed using SphygmoCor XCEL (AtCor Medical) on two visits, separated by at least one week. During each visit, vascular measures were obtained before, and 1‐ and 2‐hrs following consumption of caffeinated or placebo chewing gum. We found that cfPWV increased at 2‐hrs following consumption of caffeinated chewing gum (6.3±0.1 vs. 6.5±0.1 m·s −1 ; pre vs. 2‐hrs; P=0.017), but did not change after placebo (P>0.05). AoMAP and aoDBP increased by 6±2 and 6±1 mmHg, respectively, at 1‐hr following caffeinated chewing gum (P≤0.008) and remained elevated at 2‐hrs, but did not change in response to placebo (P>0.05). AoSBP, aoPP and heart rate did not significantly change in response to caffeinated or placebo chewing gum (P>0.05). In conclusion, caffeinated chewing gum acutely increases central arterial stiffness and aortic blood pressure in young healthy men. Future investigations should confirm these findings in women and examine whether the response is exaggerated in individuals who are hypertensive or have other risk factors for cardiovascular disease. Support or Funding Information This work was supported by the Gatorade Trust through funds distributed by the University of Florida, Department of Medicine.
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