Breno Q. Farah

Heart Rate Variability and Cardiovascular Risk Factors in Adolescent Boys

OBJECTIVE To establish reference values of heart rate variability (HRV) measures in a cohort of adolescent boys and to determine the relationship between HRV and the clustering of risk factors (RFs) for cardiovascular disease. STUDY DESIGN This cross-sectional study included 1152 adolescent boys (age: 16.6 ± 1.2 years old). Demographic data, health-related habits, obesity indicators, and blood pressure were evaluated. HRV measures of time (SD of all RR intervals, root mean square of the squared differences between adjacent normal RR intervals, and the percentage of adjacent intervals over 50 ms) and frequency domains were assessed (low [LF] and high [HF] frequency). RESULTS The components of HRV were RR interval (827 ± 128 ms), SD of all RR intervals (61.9 ± 23.5 ms), root mean square of the squared differences between adjacent normal RR intervals (54.5 ± 29.4 ms), percentage of adjacent intervals over 50 ms (29.4 ± 20.4%), LF (53 ± 16 nu), HF (47 ± 16), and LF/HF (1.44 ± 1.08). Greater sympathetic and lower parasympathetic modulation at rest were associated with higher adiposity, higher blood pressure and physical inactivity. Adolescents with 2 or more RFs also presented lower HRV than subjects with no RFs (P < .001). CONCLUSIONS The study has provided descriptive indicators that help the interpretation of HRV results in adolescents. Lower HRV measures are associated with the clustering of cardiovascular RFs.

EFFECTS OF EXERCISE INTENSITY ON RATING OF PERCEIVED EXERTION DURING A MULTIPLE-SET RESISTANCE EXERCISE SESSION

Lins-Filho, ODL, Robertson, RJ, Farah, BQ, Rodrigues, SLC, Cyrino, ES, and Ritti-Dias, RM. Effects of exercise intensity on rating of perceived exertion during a multiple-set resistance exercise session. J Strength Cond Res 26(2): 466–472, 2012—The aim of this study was to analyze the effects of intensity on rating of perceived exertion (RPE) during a multiple-set resistance exercise session. Fourteen men (22.9 ± 3.8 years) with previous experience in resistance training (22.9 ± 3.8 years) performed 2 experimental sessions in random order: resistance exercise at 50% of 1 repetition maximum (1RM) (E50%) and resistance exercise at 70% of 1RM (E70%). In both sessions, 5 exercises (bench press, bent-over row, frontal raises, arm curl, and overhead triceps extension) were performed in 3 sets of 12, 9, and 6 repetitions, respectively. Active muscle RPEs were measured after each repetition using the OMNI-Resistance Exercise Scale (OMNI-RES). In the 3 sets of 5 exercises, the RPE was higher at E70% than that at E50%. The differences in RPE between intensities were observed in both the first and the sixth repetitions for each exercise. In the E70% session, the RPE increased between sets in all exercises, whereas it did not change in the E50% session. In conclusion, the RPE was higher at 70% of 1RM than that at 50% of 1RM. Moreover, in a multiple-set prescription, the RPE did not change between sets with 50% of 1RM, whereas the RPE increased between sets with 70% of 1RM. These findings suggest that RPE can be effectively used to prescribe and monitor resistance exercise intensity during an entire multiple-set exercise session in young men with previous experience in resistance training.

Sedentary Behavior and Light Physical Activity Are Associated with Brachial and Central Blood Pressure in Hypertensive Patients

Background Physical activity is recommended as a part of a comprehensive lifestyle approach in the treatment of hypertension, but there is a lack of data about the relationship between different intensities of physical activity and cardiovascular parameters in hypertensive patients. The purpose of this study was to investigate the association between the time spent in physical activities of different intensities and blood pressure levels, arterial stiffness and autonomic modulation in hypertensive patients. Methods In this cross-sectional study, 87 hypertensive patients (57.5 ± 9.9 years of age) had their physical activity assessed over a 7 day period using an accelerometer and the time spent in sedentary activities, light physical activities, moderate physical activities and moderate-to-vigorous physical activities was obtained. The primary outcomes were brachial and central blood pressure. Arterial stiffness parameters (augmentation index and pulse wave velocity) and cardiac autonomic modulation (sympathetic and parasympathetic modulation in the heart) were also obtained as secondary outcomes. Results Sedentary activities and light physical activities were positively and inversely associated, respectively, with brachial systolic (r = 0.56; P < 0.01), central systolic (r = 0.51; P < 0.05), brachial diastolic (r = 0.45; P < 0.01) and central diastolic (r = 0.42; P < 0.05) blood pressures, after adjustment for sex, age, trunk fat, number of antihypertensive drugs, accelerometer wear time and moderate-to-vigorous physical activities. Arterial stiffness parameters and cardiac autonomic modulation were not associated with the time spent in sedentary activities and in light physical activities (P > 0.05). Conclusion Lower time spent in sedentary activities and higher time spent in light physical activities are associated with lower blood pressure, without affecting arterial stiffness and cardiac autonomic modulation in hypertensive patients.

Effects of rest interval length on rating of perceived exertion during a multiple-set resistance exercise.

This investigation analyzed the effect of rest interval length on the rating of perceived exertion (RPE) during a resistance exercise session. Nineteen males performed two experimental sessions: resistance exercise with 30-sec. rest intervals (E30) and 90-sec. rest intervals (E90). In both sessions, five exercises (bench press, knee extension, seated row, knee curl, and frontal rise) were performed at 50% 1RM in three sets of 12, 9, and 6 repetitions, respectively. In the E30 session, the RPE increased between sets in all exercises, while in the E90 session, the RPE increased from the first set to the second set in three exercises. RPE in the E30 session was higher than that in the E90 session in the third set. The results suggest that RPE increases for shorter rest intervals than for longer rest intervals. Therefore, the RPE could be considered an indicator of muscle recovery during resistance exercise.

Effects of active recovery on autonomic and haemodynamic responses after aerobic exercise

The aim of this study was to examine the effect of active recovery on autonomic and haemodynamic responses after exercise in healthy adults. Nineteen healthy young male individuals underwent two experimental sessions: exercise with active recovery (AR) and exercise with passive recovery (PR). The exercise sessions comprised three phases: warm‐up (5 min), exercise phase (cycle ergometer, 30 min, intensity between 60 and 70% of the heart rate reserve) and recovery (5 min). In the AR, the subjects remained cycling in the recovery phase at intensity between 30% and 35% of heart rate reserve, while in the PR, the subjects stopped the exercise after finishing the exercise phase. Blood pressure and heart rate were measured before and over the 30 min after the interventions. There were no differences for systolic and diastolic blood pressures, heart rate and rate pressure product between active and passive recovery sessions. Also, all heart rate variability parameters changed similarly after exercise with passive or active recovery sessions. In summary, exercise with active recovery does not affect the autonomic and haemodynamic responses after moderate‐intensity aerobic exercise in healthy young male individuals.

Acute and Chronic Effects of Isometric Handgrip Exercise on Cardiovascular Variables in Hypertensive Patients: A Systematic Review

The aim of this study was to describe, through a systematic review, the acute and chronic effects of isometric handgrip exercise on cardiovascular variables in hypertensive individuals. In this systematic review, we included studies that analyzed whether a single bout or a program with isometric exercises affect cardiovascular variables in hypertensive adults. The electronic database PubMed/Medline was searched for relevant studies published until May 2017. Of the 2927 studies initially identified, 2916 were excluded based on title and abstract and five on the basis of full-text assessment, leaving six studies remaining. In addition, one further study cited in the references of the included articles was included in this review, totaling seven studies included (five studies on the chronic effects of isometric handgrip exercise on cardiovascular parameters). None of the acute studies observed post-exercise hypotension. The majority of the chronic studies found decreases in office blood pressure after isometric handgrip training, with training ranging from 6 to 10 weeks, while heart rate variability parameters were improved in one study and did not change in another. Reduction in oxidative stress was observed; however, this variable was only analyzed in one study. In hypertensives, acute responses to isometric handgrip exercise are very limited due to the small number of studies, therefore more research is required. Furthermore, chronic isometric handgrip training reduces blood pressure; however, there is still a gap in the knowledge on the effects of this modality of exercise on other cardiovascular variables—such as endothelial function, oxidative stress, and cardiac autonomic modulation—which should be addressed in future studies.

Sedentary behavior is associated with impaired biomarkers in claudicants.

OBJECTIVE Time spent in sedentary behavior has been associated with worse inflammation and cardiometabolic biomarkers in various populations. However, the association between time spent in sedentary behavior and biomarkers remains unknown in patients with intermittent claudication. The aim of the current study was to analyze the relationship between sedentary behavior and inflammatory and cardiometabolic biomarkers in patients with symptomatic peripheral arterial disease (PAD). METHODS The sample included 297 patients with intermittent claudication. Sedentary behavior was assessed using a step activity monitor. Biomarkers of inflammation, oxidative stress, lipid profile, insulin resistance, and endogenous fibrinolysis were assessed. Demographic data, body mass index, physical activity status, and measures of severity of PAD (ankle-brachial index, peak walking time, and ischemic window) also were obtained. RESULTS Time spent in sedentary behavior was related with high-sensitivity C-reactive protein (b = 0.187; P = .005), glucose (b = 0.238; P < .001), fibrinogen (b = 0.167; P = .017), plasminogen activator inhibitor 1 activity (b = 0.143; P = .036), and high-density lipoprotein cholesterol (b = -0.133; P = .029). After adjustment for sex, age, physical activity status, body mass index, and severity of PAD, sedentary behavior remained related with high-sensitivity C-reactive protein (b = 0.170; P = .015), glucose (b = 0.178; P = .004), fibrinogen (b = 0.189; P = .010), and high-density lipoprotein cholesterol (b = -0.128; P = .032). CONCLUSIONS Time spent in sedentary activities was associated with worse inflammatory and cardiometabolic profile in patients with intermittent claudication.

Clinical predictors of ventilatory threshold achievement in patients with claudication.

PURPOSE Ventilatory threshold (VT) is considered a clinically important marker of cardiovascular function in several populations, including patients with claudication, because it is related to walking capacity and hemodynamics. The purpose of this study was to identify clinical predictors for VT achievement in patients with intermittent claudication. METHODS One hundred and seventy-seven (n = 177) patients with intermittent claudication performed a progressive graded cardiopulmonary treadmill test until maximal claudication pain. Oxygen uptake (V˙O2) was continuously measured during the test, and afterwards, VT was visually detected. Clinical characteristics, demographic data, comorbid conditions, and cardiovascular risk factors were obtained. Patients who achieved and did not achieve VT were compared, as well as the workload that VT occurred in the former group. RESULTS VT was achieved in 134 patients (76%), and the mean V˙O2 at VT for these patients was 10.8 ± 2.4 mL·kg(-1)·min(-1). Patients who did not achieve VT presented lower ankle brachial index (ABI), claudication onset time, peak walking time, and V˙O2peak, and the proportion of women was higher compared with patients who achieved VT (P < 0.05). Multiple linear regression analysis identified that sex (b = 0.25, P = 0.002), body mass index (b = -0.18, P = 0.025), peak walking time (b = 0.17, P = 0.044), and ABI (b = 0.23, P = 0.006) were predictors of V˙O2 at VT. CONCLUSIONS Forty-three patients (24%) with intermittent claudication did not achieve VT, and these patients were mostly women and those with greater severity of disease. Moreover, in those who reached VT, the predictors of poor VT were female sex, high body mass index, low peak walking time, and low ABI.

Rating of Perceived Exertion During Circuit Weight Training: A Concurrent Validation Study.

Abstract Aniceto, RR, Ritti-Dias, RM, dos Prazeres, TMP, Farah, BQ, de Lima, FFM, and do Prado, WL. Rating of perceived exertion during circuit weight training: A concurrent validation study. J Strength Cond Res 29(12): 3336–3342, 2015—The aim of this study was to determine whether rating of perceived exertion (RPE) is a valid method to control the effort during the circuit weight training (CWT) in trained men. Ten men (21.3 ± 3.3 years) with previous experience in resistance training (13.1 ± 6.3 months) performed 3 sessions: 1 orientation session and 2 experimental sessions. The subjects were randomly counterbalanced to 2 experimental sessions: CWT or multiple-set resistance training (control). In both sessions, 8 exercises (bench press, leg press 45°, seated row, leg curl, triceps pulley, leg extension, biceps curl, and adductor chair) were performed with the same work: 60% of 1 repetition maximum, 24 stations (3 circuits) or 24 sets (3 sets/exercise), 10 repetitions, 1 second in the concentric and eccentric phases, and rest intervals between sets and exercise of 60 seconds. Active muscle RPEs were measured after each 3 station/sets using the OMNI-Resistance Exercise Scale (OMNI-RES). In this same time, blood lactate was collected. Compared with baseline, both levels of blood lactate and RPE increased during whole workout in both sessions, the RPE at third, 23rd, and 27th minute and the blood lactate at third, seventh, 11th, 15th, 27th, and 31st minute were higher in multiple set compared with CWT. Positive correlation between blood lactate and RPE was observed in both experimental sessions. The results indicated that the RPE is a valid method to control the effort during the CWT in trained men and can be used to manipulate the intensity without the need to perform invasive assessments.

Acute effects of walking and combined exercise on oxidative stress and vascular function in peripheral artery disease

The aim of this study was to compare the effects of a single session of walking and combined exercise on oxidative stress and vascular function in peripheral arterial disease patients. Thirteen patients with peripheral arterial disease underwent two experimental sessions in random order: walking (ten sets of 2‐min walking at the speed corresponding to the onset of claudication pain with 2‐min interval between sets) and combined exercise (1 × 10 reps in eight resistance exercises plus five‐two‐minute sets of walking). Before and after the exercise, vascular function (blood flow, leg vascular resistance and blood‐flow postreactive hyperaemia) and oxidative stress (malondialdehyde and plasma nitrite levels) were obtained. Blood flow increased similarly after both sessions, whilst leg vascular resistance decreased similarly after both sessions. Plasma nitrite increased only after the combined exercise. Malondialdehyde decreased after both sessions, and the decrease was greater after combined exercise. As a conclusion, a single session of combined exercise improves blood flow and leg vascular resistance similarly to walking session; however, combined exercise promoted better effects on oxidative stress.