The aim of the current meta-analysis was to determine the effects of acute and chronic interval training (IT) on serum and plasma BDNF concentrations in healthy young adults. A literature search was ...performed using six databases until February 2020. The TESTEX scale was used to assess the quality of studies. Effect sizes (ES) were computed and two-tailed α values < 0.05 and non-overlapping 95% confidence intervals (95% CI) were considered statistically significant. Heterogeneity, inconsistency (I
), and small-study effects using the Luis Furuya-Kanamori (LFK) index were examined. Fifteen studies (n = 277 participants, age = 24 ± 3 years) were included. The overall effects of IT on circulating BDNF concentrations were moderate and significant (ES = 0.62, 95% CI 0.00, 1.24, heterogeneous (p < 0.001), highly inconsistent (I
= 90%), and with major asymmetry (LFK index = 2.76). The acute effect of IT on peripheral BDNF levels was large and significant (ES = 1.10, 95% CI 0.07, 2.14), heterogeneous (p < 0.001), highly inconsistent (I
= 92%), and with major asymmetry (LFK index = 3.34). The chronic effect of IT on circulating BDNF was large and significant (ES = 0.93, 95% CI 0.40, 1.46), heterogeneous (p < 0.001), with moderate inconsistency (I
= 70%), and minor asymmetry (LFK index = 1.21). Acute and chronic IT elicited a moderate increase in serum and plasma BDNF concentrations in a healthy young population.
Hypertension affects 25% of the world's population and is considered a risk factor for cardiovascular disorders and other diseases. The aim of this study was to examine the evidence regarding the ...acute effect of exercise on blood pressure (BP) using meta-analytic measures. Sixty-five studies were compared using effect sizes (ES), and heterogeneity and Z tests to determine whether the ES were different from zero. The mean corrected global ES for exercise conditions were -0.56 (-4.80 mmHg) for systolic BP (sBP) and -0.44 (-3.19 mmHg) for diastolic BP (dBP; z ≠ 0 for all; p < 0.05). The reduction in BP was significant regardless of the participant's initial BP level, gender, physical activity level, antihypertensive drug intake, type of BP measurement, time of day in which the BP was measured, type of exercise performed, and exercise training program (p < 0.05 for all). ANOVA tests revealed that BP reductions were greater if participants were males, not receiving antihypertensive medication, physically active, and if the exercise performed was jogging. A significant inverse correlation was found between age and BP ES, body mass index (BMI) and sBP ES, duration of the exercise's session and sBP ES, and between the number of sets performed in the resistance exercise program and sBP ES (p < 0.05). Regardless of the characteristics of the participants and exercise, there was a reduction in BP in the hours following an exercise session. However, the hypotensive effect was greater when the exercise was performed as a preventive strategy in those physically active and without antihypertensive medication.
The brain-derived neurotrophic factor (BDNF) is a protein mainly synthetized in the neurons. Early evidence showed that BDNF participates in cognitive processes as measured at the hippocampus. This ...neurotrophin is as a reliable marker of brain function; moreover, recent studies have demonstrated that BDNF participates in physiological processes such as glucose homeostasis and lipid metabolism. The BDNF has been also studied using the exercise paradigm to determine its response to different exercise modalities; therefore, BDNF is considered a new member of the exercise-related molecules. The high-intensity interval training (HIIT) is an exercise protocol characterized by low work volume performed at a high intensity i.e., ≥80% of maximal heart rate (HRmax). Recent evidence supports the contention that HIIT elicits higher fat oxidation in skeletal muscle than other forms of exercise. Similarly, HIIT is a good stimulus to increase maximal oxygen uptake (VO
max). Few studies have investigated the impact of HIIT on the BDNF response. The present work summarizes the effects of acute and long-term HIIT on BDNF.
Briceño-Torres, JM, Carpio-Rivera, E, Solera-Herrera, A, Forsse, J, Grandjean, PW, and Moncada-Jiménez, J. Low-intensity resistance training improves flow-mediated dilation in young hispanic adults. ...J Strength Cond Res 37(2): 298-304, 2023-The purpose of this study was to compare the effects of 2 resistance exercise training (RET) intensities on brachial artery flow-mediated dilatation (FMD) in sedentary males. Thirty-four men (age = 20.6 ± 1.8 years, height = 171.3 ± 5.2 cm, body mass = 65.2 ± 10.6 kg, and DXA fat mass = 22.3 ± 7.4%) were randomly assigned to a control group (no exercise CTRL, n = 12), RET at 50% of 1 repetition maximum (1RM) (RET50%, n = 12), and RET at 80% 1RM (RET80%, n = 10). The RET program was performed twice per week for 8 weeks; subjects performed the same RET exercises at similar total workloads (1920 arbitrary units AUs for the RET80% and 1950 AUs for the RET50%). The FMD% was measured before and after 8 weeks by ultrasound. Mixed factorial analysis of variance (3 groups × 2 measurements), effect size (ES), and 95% confidence intervals (95% CIs) were computed for FMD%. The level of significance was set at p ≤ 0.05. A significant increase ( p = 0.001) was found on post-test FMD% in RET50% (mean = 9.9 ± 3.7%, ES = 1.9, and 95% CIs = 2.8-0.9) compared with CTRL (mean = 5.7 ± 1.7%, ES = 0.2, and 95% CIs = -0.4 to 0.8), and there were no significant differences found between RET50% and RET80% and between RET80% and CTRL. Results support the concept of training specificity and provide preliminary evidence that lower resistance and higher repetition RET elicit greater short-term reduced endothelium dysfunction than higher intensity RET at similar training volume.
We studied the effect of exercise-induced body fluid redistribution on dual-energy x-ray absorptiometry (DXA) body composition scores. Thirty males completed 30-min of upper-body exercise (UBE), ...lower-body exercise, and seated non-exercise control (NEC). ANOVA determined interactions between experimental conditions and measurements on body composition variables. For UBE, mean pre to post differences were found on tissue fat (M = 0.35 ± 0.12%; CI95%diff = 0.10 to 0.59%; p = 0.007), region fat (M = 0.32 ± 0.11%; CI95%diff = 0.09 to 0.55%; p = 0.008), lean mass (M = 0.27 ± 0.01 kg; CI95%diff = 0.18 to 0.37 kg; p ≤ 0.0001), and total mass (M = 0.27 ± 0.05 kg; CI95%diff = 0.17 to 0.36 kg; p ≤ 0.0001). Mean tissue pre to post differences were found for the total body in the NEC (M = 0.10 ± 0.04 kg; CI95%diff = 0.03 to 0.18 kg; p = 0.008), UBE (M = 0.19 ± 0.03 kg; CI95%diff = 0.14 to 0.24 kg; p ≤ 0.0001), and LBE (M = 0.31 ± 0.04 kg; CI95%diff = 0.24 to 0.39 kg; p ≤ 0.0001) conditions. High absolute reliability was found within experimental conditions. These findings have practical implications for technicians, since acute exercise elicited small changes in body composition scores using DXA.
Glycemic control is essential to reduce the risk of complications associated with metabolic syndrome (MetS) and type 2 diabetes (T2D). Aerobic and resistance exercise performed alone or in ...combination improve glycemic control in both conditions. However, perceived lack of time and commitment are considered principal barriers to performing exercise regularly. High intensity interval training (HIIT) and sprint interval training (SIT) can be performed in a fraction of the time required for continuous aerobic exercise. A substantial scientific evidence indicates that HIIT/SIT improve glycemic control to a similar or greater extent than aerobic exercise in populations without MetS or T2D. Likewise, growing evidence suggest that HIIT/SIT improve the glycemic control during MetS and T2D. The aim of this review is to discuss the effects of interval training protocols on peripheral markers of glucose metabolism in patients with MetS and T2D.
•Either form of interval training (HIIT or SIT) using a treadmill or cycle ergometer improves insulin sensitivity (IS) in skeletal muscle.•Interval training does not appear to modify the insulin sensitivity (IS) in liver during MetS and T2D.•Long-term interval training reduces HbA1c levels during MetS or T2D.
Brain-derived neurotrophic factor (BDNF) increases neuronal viability and cognitive function, peripheral lipid metabolism and skeletal muscle repair. The primary purpose of this study was to ...determine the effect of short-term high-intensity interval training (HIIT) on serum BDNF concentrations in healthy young women.
Seventeen women (age:22 ± 1 years); body mass index (BMI:24.2 ± 2.2 kg/m²), body fat percentage (% fat:25.8 ± 4.7) participated in the study. Participants were randomly assigned to a control (
= 8) or HIIT group (
= 9). All participants performed a graded exercise test (GXT) on an electronically-braked cycle ergometer to determine maximal aerobic power (MAP, Watts). HIIT was performed three days per week for four weeks. Each HIIT session consisted of three to five cycling bouts of 30 s each at 80% MAP, followed by four-minutes of recovery at 40% MAP. Forty-eight hours after the last bout of exercise, both groups performed a follow-up GXT. Non-fasting blood samples were collected before and immediately after each GXT. Mixed factorial (2 groups x 4 measures, and 2 groups x 2 measures) ANOVA was used to assess BDNF concentrations, performance and anthropometric variables.
Serum BDNF concentrations in the HIIT group (21.9 ± 1.3 ng/mL) increased compared to control (19.2 ± 2.8 ng/mL) (∼12%,
< 0.05) following HIIT. In contrast, circulating BDNF concentrations were reduced following the GXT (
< 0.05). The MAP and % Fat did not change with HIIT.
Twelve sessions of HIIT increases circulating BDNF concentrations in healthy young women despite no change in physical performance or % fat.
•International Simple Glass (ISG) made by Mo-SCI Corporation subjected to γ-irradiation.•Thermal bleaching evaluated in real-time by in situ UV/Vis optical microspectroscopy.•Non-isothermal ...methodology for kinetic analysis coined temperature scanning bleaching spectroscopy proposed.
The thermal bleaching of γ-irradiated (0.83 and 1.99 MGy) nuclear waste glass simulant known as International Simple Glass (ISG, made by Mo-SCI Corporation, Rolla, MO) was studied in real time by non-isothermal in situ UV/Vis optical microspectroscopy. The method follows the Urbach energy temperature/time evolution for three constant heating rates. A novel opto-thermal technique for kinetic analysis, coined temperature scanning bleaching spectroscopy (TSBS) is proposed. The applicability of the Kissinger equation is extended by synergistic inflection point analysis of the Urbach energy time/temperature sigmoid. The sigmoidal behavior is discussed in the context of polaron time/temperature trends of the main factors of thermally generated polaron flux. The overall activation energy of the non-isothermal thermal bleaching is evaluated at 1.6 (±0.1) and 1.3 (±0.2) eV, for 0.83 and 1.99 MGy, respectively. The proposed TSBS methodology is applicable for real-time monitoring and robust quantitative comparison of non-isothermal thermal bleaching of any glassy material.
Acute bouts of intense exercise increase lactate concentration, which in turn stimulates brain-derived neurotrophic factor (BDNF) production. Cortisol released during intense exercise might inhibit ...BDNF synthesis. This study examined the acute effects of 2 protocols of strenuous exercise on serum BDNF. Seventeen physically-active healthy females (Age = 20.0 ± 0.9 yr., BMI = 23.0 ± 2.6 kg/m2) performed a strenuous cycle-ergometer graded exercise test (GXT) and a high-intensity interval training session (HIIT). Serum BDNF, serum cortisol, cortisol: BDNF ratio and blood lactate (BLa) were recorded at baseline and immediately following exercise. Although non-statistically significant, the HIIT session elicited a higher magnitude of change from baseline for BDNF (d = 0.17) and cortisol (d = 1.18) than after the GXT (d = -0.26, and d = 0.82, respectively). An interaction was found between GXT and HIIT trials and measurements on BLa levels, with higher post-exertion values after HIIT than after GXT (p < 0.0001, η2 = 0.650, 95%CI = 2.2, 5.2). The higher BLa levels did not raise circulating BDNF. The elevated cortisol levels may have overcome the effects of lactate on BDNF. However, the higher BLa induced by HIIT suggest that interval exercise modality on the long-term could be a feasible intervention to increase circulating peripheral BDNF, at least in untrained healthy women.
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