Irisin Levels Are not Associated to Resistance Training-Induced Alterations in Body Mass Composition in Older Untrained Women with and without Obesity.

OBJECTIVE: The present study aimed to determine whether Irisin levels are correlated with body composition changes following 16 weeks of resistance training (RT) in older women with and without obesity. Design, Setting, Participants, Intervention: We recruited 49 inactive women (n = 23, non-obese: < 41.0% and n = 26, obese: ≥ 41.0% of body fat) aged 61-68 years to perform 16-week of RT consisting of 10 exercises (three sets of 10 exercises, 6-12 repetitions maximum and 1-min and 30-s rest intervals between sets and exercises, respectively) with two sessions per week. MEASUREMENTS: Before and after the intervention period, blood samples were collected to determine Irisin levels and body composition (percentage body fat and fat-free mass) was measured by dual energy x-ray absorptiometry. RESULTS: Circulating Irisin displayed a decrease for the non-obese group as compared with pre-intervention and obese group (p = 0.01 and p = 0.04, respectively), with no change for the obese group (p = 0.79). In addition, fat mass displayed a significant reduction (p < 0.05) following the training period only for the obese group. Furthermore, there was no association between changes in circulating Irisin with body mass index, body fat, fat-free mass and muscle strength. There was an increase in muscle strength (p < 0.05), regardless of obesity status. CONCLUSION: The modulation of body composition and muscle strength induced by 16-week of resistance training in older women with and without obesity is not associated with changes in circulating Irisin levels.

Inter- and Intra-Individual Analysis of Post-Exercise Hypotension Following a Single Bout of High-Intensity Interval Exercise and Continuous Exercise: A Pilot Study.

Recently, post-exercise blood pressure (BP) has been considered a predictive tool to identify individuals who are responsive or not to BP reductions with exercise training (i. e., "high" and "low responders"). This study aimed to analyze the inter- and intra-individual BP responsiveness following a single bout of high-intensity interval exercise (HIIE) and continuous exercise (CE) in normotensive men (n=14; 24.5±4.2 years). Mean change in BP during the 60 min period post-exercise was analyzed and minimal detectable change (MDC) was calculated to classify the subjects as "low" (no post-exercise hypotension [PEH]) and "high responders" (PEH occurrence) following each exercise protocol (inter-individual analysis). The MDC for systolic and diastolic BP was 5.8 and 7.0 mmHg. In addition, a difference equal/higher than MDC between the exercise protocols was used to define an occurrence of intra-individual variability in BP responsiveness. There were "low" and "high" PEH responders following both exercise protocols (inter-individual variability) as well as subjects who presented higher PEH following a specific exercise protocol (intra-individual variability between exercise protocols). These results were observed mainly for systolic BP. In summary, PEH is a heterogeneous physiological phenomenon and, for some subjects, seems to be exercise-protocol dependent. Further investigations are necessary to confirm our preliminary findings.

Similar hypotensive responses to resistance exercise with and without blood flow restriction.

Low intensity resistance exercise (RE) with blood flow restriction (BFR) has gained attention in the literature due to the beneficial effects on functional and morphological variables, similar to those observed during traditional RE without BFR, while the effects of BFR on post-exercise hypotension remain unclear. The aim of the present study was to compare the blood pressure (BP) response of trained normotensive individuals to RE with and without BFR. In this cross-over randomized trial, eight male subjects (23.8 ± 4 years, 74 ± 3 kg, 174 ± 4 cm) completed two exercise protocols: traditional RE (3 x 10 repetitions at 70% one-repetition maximum [1-RM]) and low intensity RE (3 x 15 repetitions at 20% 1-RM) with BFR. Blood pressure measurements were performed after 15 min of seated rest (0), immediately after and 10 min, 20 min, 30 min, 40 min, 50 min and 60 min after the experimental sessions. Similar hypotensive effects for systolic BP (SBP) were observed for both protocols (P < 0.05) after exercise, with no differences between groups (P > 0.05) and no statistically significant difference for diastolic BP (P > 0.05). These results suggest that in normotensive trained individuals, both traditional RE and RE with BFR induce hypotension for SBP, which is important to prevent cardiovascular disturbances.

Correlation between acute and chronic 24-hour blood pressure response to resistance training in adult women.

The purpose of the present study was to correlate the acute and chronic decrease in blood pressure (BP) following resistance training (RT). 13 normotensive women (18-49 years) completed an acute whole body RT session with 3 sets of 10 repetitions at 60% 1RM and then 8 weeks of RT as follows: 3/week, 3 sets of 8-12 repetitions maximum. Systolic (SBP) and diastolic BP (DBP) were measured up to 60 min and 24 h following RT (acute and chronic). The greatest acute decrease of SBP (108.5±7.0 mmHg) and DBP (71.5±6.4 mmHg) values over the 60-min period were reduced compared to pre-exercise (117.3±11.7 and 79.3±8.2 mmHg, respectively; p<0.05). The chronic effect on resting BP was observed only for those presenting acute post-exercise hypotension (PEH). The change in both SBP and DBP following acute RT was correlated with the chronic change in resting SBP and DBP (r>0.5; p≤0.05). The change in 24 h BP after acute RT was correlated with the chronic reduction in SBP (r=0.74) and DBP (r=0.80). The magnitude of PEH is a promising candidate for the prediction of individual BP-related training efficacy.

The acute response of apoptosis and migration to resistance exercise is protocol-dependent.

The aim of the present study was to compare the acute effects of resistance exercise (RE) designed for hypertrophy or local muscle endurance (LME) on CD4+ and CD8+ T cell apoptosis and migration. 14 untrained subjects (age 20.5±0.8 years, body mass 70.0±12.8 kg, body mass index 24.0±3.2 kg/m(2)), women (N=11) and men (N=3) completed 2 RE sessions (3 sets of 9 exercises) designed for hypertrophy at 10 repetitions maximum (RM) and LME at 60% of 10RM with 1-min rest-intervals between sets and exercises. The investigated lymphocytes were: CD4+, CD4+/CD69RA+, CD8+ and CD8+/CD69RA+ with cell surface markers annexin V and CX3CR1 analyzed by flow cytometry. Percentage of CD4+ positive for annexin V+ were higher immediately following and 24 h after the hypertrophy protocol as compared with LME, while CD4+ positive for CX3CR1 were higher immediately after and lower at the 24 h time point after LME as compared with the hypertrophy session. CD8+ lymphocytes responded similarly to the hypertrophy and LME protocols with elevations in both cellular migration and cell death immediately following and 24 h after the bouts (p≤0.05). Considering that the acute response of CD4+ lymphocytes to RE is protocol-dependent, a gradual adaptation to a hypertrophy program could minimize the effect on CD4+ lymphocytes and reduce the potential susceptibility to antigens during this timeframe. This would also be interesting for a RE program designed for LME based on the observed CD8+ lymphocyte response.

Acute effects of resistance exercise on 24-h blood pressure in middle aged overweight and obese women.

This investigation was designed to evaluate responses of blood pressure (BP) following an acute resistance exercise (RE) session. Middle-aged women (N=13) who were classified as overweight (N=8) or obese (N=5) according to body mass index (BMI) participated in the investigation. Participants were randomly submitted to a control session (30-min seated rest) and a exercise session (3 sets, 10 repetitions at 60% 1RM of exercises for the upper and lower body) with systolic (SBP), diastolic (DBP) and mean blood pressure (MBP) obtained at rest and 10, 20, 30, 40, 50, and 60-min following exercise, and through 24 h. Acute RE decreased SBP at 10, 30, and 40-min compared with pre-exercise and control (P<0.05). DBP decreased at 10 and 40-min post-exercise compared with the control trial (P<0.05). Both SBP and DBP decreased in the nighttime period (-4.2 mmHg and -4.1 mmHg, respectively) and in the overall 24 h period (-3.6 mmHg and -4.5 mmHg, respectively) following the acute RE session when compared with the control trial. These findings indicate important benefits of acute RE on BP circadian rhythm, particularly at night as well as in the morning, which are critical periods associated with increased risk for cardiovascular events.

Acute resistance training affects cell surface markers for apoptosis and migration in CD4⁺ and CD8⁺ lymphocytes.

The purpose of the present study was to examine the acute effects of resistance training (RT) on CD4⁺ and CD8⁺ T lymphocytes apoptosis (annexin V⁺) and migration (CX3CR1). Twelve subjects performed two RT sessions (3 sets of 9 exercises) with 1 min (Hyper-1) and 3 min (Hyper-3) of rest-interval length between sets and exercises. CD4⁺ and CD8⁺ cells count displayed no change following Hyper-1 and Hyper-3. There was an increase in the percentage of CD4⁺ positive for annexin V⁺ and CX3CR1⁺ immediately after and 24 h post Hyper-1. Percentage of CD4⁺ positive for annexin V⁺ increased 2 and 24 h post Hyper-3, and decreased after CXCR1⁺ for the same time-points. There was an increase in CD8⁺ positive for annexin V⁺ and CX3CR1⁺ immediately after, 2 and 24 h post Hyper-1 and Hyper-3, while no differences were found between Hyper-1 and Hyper-3. Acute RT increase the apoptosis and migration of CD4⁺ and CD8⁺ lymphocytes even 24h after exercise, with minimal effects of rest-interval length.