Physiological responses in different intensities of resistance exercise - Critical load and the effects of aging process.

Aim was to identify critical load (CL) in young and elderly apparently healthy male cohorts. To contrast the metabolic, cardiovascular and perceptual responses on CL according to age. We evaluated 12 young (23 ± 3 years) and 10 elderly (70 ± 2 years) apparently healthy active males, who underwent: (1) 1 repetition maximum (1RM) test on a 45° Leg Press; (2) on different days, three high-intensity resistance exercise constant load tests (60%, 75% and 90% 1RM) until fatigue (Tlim). Absolute values of both the CL asymptote and curvature constant (kg) were significantly lower in elderly subjects (P < 0.05). In contrast, elderly subjects demonstrated a significantly higher number of repetitions at CL when compared with young subjects (P < 0.05). As expected, oxygen uptake (VO2) and heart rate (HR) during maximal aerobic exercise testing were significantly reduced in older subjects. However, percent-predicted aerobic capacity were higher in older subjects (P < 0.05). In addition, blood lactate ([La-]) corrected to Tlim and rating of perceived exertion values were greater in younger subjects at all intensities (P < 0.05). These findings, despite reduced force production in older subjects, endurance-related parameters are well preserved according to age-adjusted percent-predicted values in apparently healthy males.

Photobiomodulation increases mitochondrial citrate synthase activity in rats submitted to aerobic training.

This study investigated the effects of photobiomodulation by low-laser laser therapy (LLLT) on the activities of citrate synthase (CS) and lactate dehydrogenase (LDH) and the anaerobic threshold (AT) in rats submitted to treadmill exercise. Fifty-four rats were allocated into four groups: rest control (RCG), rest laser (RLG), exercise control (ECG), and exercise laser (ELG). The infrared LLLT was applied daily on the quadriceps, gluteus maximum, soleus, and tibialis anterior muscles. Muscle samples (soleus, tibialis anterior, and cardiac muscles) were removed 48 h after the last exercise session for spectrophotometric analysis of the CS and LDH. The CS activity (µmol/protein) in ELG (16.02 and 0.49) was significantly greater (P < 0.05) than RCG (2.34 and 0.24), RLG (6.25 and 0.17), and ECG (6.76 and 0.26) in the cardiac and soleus muscles, respectively. The LDH activity (in 1 Mm/protein) in soleus muscle was smaller (P < 0.05) for ELG (0.33) compared to ECG (0.97), RLG (0.79), and RCG (1.07). For cardiac muscle, the LDH activity was smaller (P < 0.05) in ELG (1.38) compared to ECG (1.91) and RCG (2.55). The ECG and ELG showed increases in the maximum speed and a shift of the AT to higher effort levels after the training period, but no differences occurred between the exercised groups. In conclusion, the aerobic treadmill training combined with LLLT promotes an increase of oxidative capacity in this rat model, mainly in muscles with greater aerobic capacity.

Double product break point estimates ventilatory threshold in individuals with type 2 diabetes.

[Purpose] To verify the identification of the anaerobic threshold through the double product breakpoint (DPBP) method for individuals with type 2 diabetes. [Subjects and Methods] Nine individuals with T2D (7 females; age=63.2 ± 8.9 y) and 10 non-diabetic (ND) (7 females; age=58.3 ± 7.8 y) performed an incremental exercise test on a cycle ergometer. Heart rate (HR), blood pressure (BP) and expired gas were measured at the end of each stage. The ventilatory threshold (VT) and DPBP were considered as the exercise intensities above which an over proportional increases in VE and DP were observed in relation to increasing workload. [Results] No differences were observed between the workloads, HR and VO2 corresponding to the AT identified respectively by VT and DPBP. For the T2D, strong correlations between VT and DBPB workloads (r=0.853), HR (r=0.714), and VO2 (r=0.863) were found. These relationships were similar to those found for the control group (r=0.923; r=0.881; and r=0.863, respectively). [Conclusion] These results demonstrate that the DPBP enables for the prediction of AT and correlated well the VT in both the T2D and ND participants.

Effects of low-level laser therapy (808 nm) on isokinetic muscle performance of young women submitted to endurance training: a randomized controlled clinical trial.

Low-level laser therapy (LLLT) has shown efficacy in muscle bioenergetic activation and its effects could influence the mechanical performance of this tissue during physical exercise. This study tested whether endurance training associated with LLLT could increase human muscle performance in isokinetic dynamometry when compared to the same training without LLLT. The primary objective was to determine the fatigue index of the knee extensor muscles (FIext) and the secondary objective was to determine the total work of the knee extensor muscles (TWext). Included in the study were 45 clinically healthy women (21 ± 1.78 years old) who were randomly distributed into three groups: CG (control group), TG (training group) and TLG (training with LLLT group). The training for the TG and TLG groups involved cycle ergometer exercise with load applied to the ventilatory threshold (VT) for 9 consecutive weeks. Immediately after each training session, LLLT was applied to the femoral quadriceps muscle of both lower limbs of the TLG subjects using an infrared laser device (808 nm) with six 60-mW diodes with an energy of 0.6 J per diode and a total energy applied to each limb of 18 J. VT was determined by ergospirometry during an incremental exercise test and muscle performance was evaluated using an isokinetic dynamometer at 240°/s. Only the TLG showed a decrease in FIext in the nondominant lower limb (P = 0.016) and the dominant lower limb (P = 0.006). Both the TLG and the TG showed an increase in TWext in the nondominant lower limb (P < 0.001 and P = 0.011, respectively) and in the dominant lower limb (P < 0.000 and P < 0.000, respectively). The CG showed no reduction in FIext or TWext in either lower limb. The results suggest that an endurance training program combined with LLLT leads to a greater reduction in fatigue than an endurance training program without LLLT. This is relevant to everyone involved in sport and rehabilitation.

Metabolic and cardiac autonomic effects of high-intensity resistance training protocol in Wistar rats.

The aim of this study was to assess the effects of metabolic and autonomic nervous control on high-intensity resistance training (HRT) as determined by pancreatic glucose sensitivity (GS), insulin sensitivity (IS), blood lactate ([La]), and heart rate variability (HRV) in rats. Thirty male, albino Wistar rats (292 ± 20 g) were divided into 3 groups: sedentary control (SC), low-resistance training (LRT), and HRT. The animals in the HRT group were submitted to a high-resistance protocol with a progressively increasing load relative to body weight until exhaustion, whereas the LRT group performed the same exercise regimen with no load progression. The program was conducted 3 times per week for 8 weeks. The [La], parameters related to the functionality of pancreatic tissue, and HRV were measured. There was a significant increase in peak [La] only in the HRT group, but there was a reduction in [La] when corrected to the maximal load in both trained groups (LRT and HRT, p < 0.05). Both trained groups exhibited an increase in IS; however, compared with SC and LRT, HRT demonstrated a significantly higher GS posttraining (p < 0.05). With respect to HRV, the low-frequency (LF) band, in milliseconds squared, reduced in both trained groups, but the high-frequency band, in milliseconds squared and nu, increased, and the LF in nu, decreased only in the HRT group (p < 0.05). The HRT protocol produced significant and beneficial metabolic and cardiac autonomic adaptations. These results provide evidence for the positive benefits of HRT in counteracting metabolic and cardiovascular dysfunction.

Effects of low level laser therapy (808 nm) on physical strength training in humans.

Recent studies have investigated whether low level laser therapy (LLLT) can optimize human muscle performance in physical exercise. This study tested the effect of LLLT on muscle performance in physical strength training in humans compared with strength training only. The study involved 36 men (20.8±2.2 years old), clinically healthy, with a beginner and/or moderate physical activity training pattern. The subjects were randomly distributed into three groups: TLG (training with LLLT), TG (training only) and CG (control). The training for TG and TLG subjects involved the leg-press exercise with a load equal to 80% of one repetition maximum (1RM) in the leg-press test over 12 consecutive weeks. The LLLT was applied to the quadriceps muscle of both lower limbs of the TLG subjects immediately after the end of each training session. Using an infrared laser device (808 nm) with six diodes of 60 mW each a total energy of 50.4 J of LLLT was administered over 140 s. Muscle strength was assessed using the 1RM leg-press test and the isokinetic dynamometer test. The muscle volume of the thigh of the dominant limb was assessed by thigh perimetry. The TLG subjects showed an increase of 55% in the 1RM leg-press test, which was significantly higher than the increases in the TG subjects (26%, P = 0.033) and in the CG subjects (0.27%, P < 0.001). The TLG was the only group to show an increase in muscle performance in the isokinetic dynamometry test compared with baseline. The increases in thigh perimeter in the TLG subjects and TG subjects were not significantly different (4.52% and 2.75%, respectively; P = 0.775). Strength training associated with LLLT can increase muscle performance compared with strength training only.

Effects of ovariectomy and resistance training on MMP-2 activity in rat calcaneal tendon.

Tendon remodeling relies on extracellular matrix (ECM) restructuring by the matrix metallopeptidases (MMPs). The aim of this study was to investigate MMP-2 activity in different regions of the calcaneal tendon (CT) after resistance training (RT) in ovariectomized rats. Wistar adult female rats were grouped into sedentary (Sed-Intact), ovariectomized sedentary (Sed-Ovx), acute exercise (AcuteEx-Intact), ovariectomized acute exercise (AcuteEx-Ovx), resistance trained (ChronicEx-Intact), and ovariectomized resistance trained (ChronicEx-Ovx) (n = 10 each group). The RT protocol required the animals to climb a 1.1-m vertical ladder with weights attached to their tail. The sessions were performed once every 3 days with 4-9 climbs and 8-12 dynamic movements per scaling. The acute groups performed one session and the chronic groups underwent 12 weeks of RT. There was an increase in total MMP-2 activity in Sed-Ovx, AcuteEx-Intact, and ChronicEx-Intact compared with that in Sed-Intact in the proximal region of CT. AcuteEx-Ovx exhibited higher total MMP-2 than Sed-Ovx and AcuteEx-Intact in the distal region of CT. Chronic-Ovx presented lower total MMP-2 activity than Sed-Ovx and Chronic-Intact in the distal region of tendon. The active MMP-2 was higher for the AcuteEx-Ovx than Sed-Ovx and AcuteEx-Intact in proximal region of tendon. There was higher active MMP-2 in the distal region of tendon in the Acute-Ovx than in the Sed-Ovx and AcuteEx-Intact. Ovariectomy and resistance exercise modulate MMP-2 activity according to specific tendon region, indicating a differentiated tissue remodeling.

Heart-rate variability and blood-lactate threshold interaction during progressive resistance exercise in healthy older men.

The objective of this study was to (a) evaluate the impact of the leg press, at variable percentages of 1 repetition maximum (1RM), on heart rate variability (HRV) and blood lactate and (b) determine the relationship between HRV with blood lactate in a healthy elderly cohort. Ten healthy men (64 +/- 4 years) participated in a progressive leg-press protocol to maximal exertion. Initially, 1RM for the leg press was determined for all subjects. The protocol then began at 10% of 1RM, with subsequent increases of 10% until 30% of 1RM, followed by incremental adjustments of 5% until exhaustion. The measurement of instantaneous R-R interval variability from Poincare plots (SD1 and SD2) and time domain indexes (RMSSD and RMSM), blood pressure, and blood lactate were obtained at rest and all leg-press loads. Significant alterations of HRV and blood lactate were observed from 30% of 1RM leg press (p < 0.05). Additionally, significant correlations were found between the lactate threshold (LT) and the RMSSD threshold (r = 0.78; p < 0.01), and between the LT and SD1 threshold (r = 0.81, p < 0.01). We conclude that metabolic and cardiovascular alterations are apparent during relatively low resistance exercise (RE) loads in apparently healthy subjects. In addition, HRV indexes were associated with blood-lactate levels during RE. The practical applications is the possibility of using HRV as a noninvasive measure obtained at a relatively low cost may be used to identify neural and metabolic alterations during RE in older subjects.

Effects of resistance training on resistin, leptin, cytokines, and muscle force in elderly post-menopausal women.

It may be that resistance exercise can be used to prevent the degenerative processes and inflammation associated with ageing. Thus, the aim of the present study was to evaluate the effects of resistance training on cytokines, leptin, resistin, and muscle strength in post-menopausal women. Thirty-five sedentary women (mean age 63.18 years, s = 4.8; height 1.64 m, s = 0.07; body mass 57.84 kg, s = 7.70) were recruited. The 16 weeks of periodized resistance training consisted of two weekly sessions of three sets of 6-14 repetition maximum. Maximal strength was tested in bench press, 45 degrees leg press, and arm curl. Plasma tumour necrosis factor-alpha, interleukin-6, interleukin-15, leptin, and resistin were determined by enzyme-linked immunosorbent assay. Maximal strength on all measures was increased after 16 weeks. There were minor or no modifications in tumour necrosis factor-alpha and interleukin-15. Interleukin-6 was decreased 48 h after compared with baseline and declined after 16 weeks. Leptin decreased 24 h after compared with baseline and was reduced at baseline and 48 h after compared with pre-training. There was a decrease in resistin after 24 and 48 h compared with baseline and a decline in baseline and immediately after levels compared with pre-training. A possible explanation of the results of the present study is a lower production of pro-inflammatory cytokines by the innate immune system. Periodized resistance training seems to be an important intervention to reduce systemic inflammation in this population.

Lactate and ventilatory thresholds in type 2 diabetic women.

Anaerobic threshold (AT) has been considered the optimal exercise intensity for type 2 diabetes mellitus (DM 2) patients, but there is little information about the comparison between lactate (LT) and ventilatory (VT) thresholds in this population, particularly during treadmill exercise. Therefore, we evaluated DM 2 women in order to compare and analyze the relationships between VT and LT intensities. Fifteen women with DM 2 without complications and comorbidities (50.7 +/- 8.0 years; 71.3 +/- 8.6 kg; 154 +/- 5 cm; 37.8 +/- 3.9% fat; 4.7 +/- 3.2 years of disease diagnose and 138 +/- 45 mg/dl fasting glucose) were subjected to a graded treadmill test-initial velocity and increments of 1 km/h every 2 min until voluntary exhaustion. VT was determined from V(E)/V(O(2)) and V(E)-V(CO(2)) ratios and LT was defined as the point at which a first increase in blood lactate occurs during incremental test. Our results showed no significant differences (p > 0.05) and significant correlations between VT and LT expressed in velocity (4.7 +/- 0.7 versus 4.6 +/- 0.7 km/h, r = 0.62), absolute V(O(2)) (1.27 +/- 0.33 versus 1.24 +/- 0.28 l min(-1), r = 0.93); relative V(O(2)) (18.3 +/- 5.7 versus 17.6 +/- 4.6 ml kg(-1) min(-1), r = 0.84) and %V(O(2)(max)) (80 +/- 12 versus 78 +/- 10%, r = 0.82). These results suggest that both VT and LT can be used to access AT in DM 2 women during graded treadmill exercise.

Isoflavone-supplemented soy yoghurt associated with resistive physical exercise increase bone mineral density of ovariectomized rats.

OBJECTIVE: To determine the effects produced by the ingestion of a fermented soy product (soy yoghurt), supplemented with isoflavones and associated with a resistive exercise program, on the bone metabolism of mature ovariectomized (Ovx) and sham-ovariectomized (sham-Ovx) rats. METHODS: A total of 56 rats were used. They were divided into 2 sedentary control groups, the Ovx control group (C-Ovx) and the sham-Ovx control group (C-Sovx), each with 7 sedentary animals, and 2 treated groups, Ovx and sham-Ovx, with 21 animals each. These two treated groups were subdivided into three subgroups of seven animals each, which received the following treatments: consuming the soy yoghurt+sedentary, only subjected to resistive exercise, and consuming the soy yoghurt+resistive exercise. Both the program of resistive exercise and the consumption of soy yoghurt (at 3 mL/(kg body weight day)) continued for 12 weeks. The soy yoghurt was supplemented with isoflavones at 50mg/100g of product. The animals were sacrificed and their right-side femurs and tibias removed and assessed for bone mineral density (BMD). The alkaline phosphatase activity (AP) was determined in the blood serum. RESULTS: There was a significant increase in both femur and tibia BMD values and in serum alkaline phosphatase activity in all the treated subgroups, compared with the control groups (p<0.05). CONCLUSION: The ingestion of the soy yoghurt supplemented with isoflavones was capable of preventing a loss of bone mass in Ovx rats and of increasing bone mass in sham rats, whilst the resistive exercise program was effective in augmenting the bone mass in sham and Ovx rats.

The impact of noninvasive ventilation during the physical training in patients with moderate-to-severe chronic obstructive pulmonary disease (COPD).

OBJECTIVE: To evaluate the influence of physical training with or without noninvasive ventilation at 2 levels of pressure in the airways (BiPAP) in patients with chronic obstructive pulmonary disease. METHODS: Eighteen patients with FEV(1) = 34 +/- 8% of predicted values, mean age of 68 +/- 9 years were randomly distributed into 2 groups, one group performing physical training on a treadmill and the other group performing physical training associated with BiPAP (physical training+B), for 30 minutes, 3 times a week for 12 weeks. The training velocity was based on a test of cardiopulmonary force performed pre- and postintervention, which registered the values for heart rate, systolic blood pressure, diastolic blood pressure, peripheral oxygen saturation, blood lactate, sensation of dyspnea, respiratory muscle strength, and analysis of gases expired such as oxygen consumption and the production of carbon dioxide. RESULTS: For both groups, there was a significant improvement in dyspnea and peripheral oxygen saturation at identical levels of physical exercise, in distance walked during the physical training, and in respiratory muscle strength (P < 0.05). Only the physical training+B group had a significant improvement in heart rate, systolic blood pressure, and oxygen consumption after training (P < 0.05). Significant reductions of blood lactate were observed at identical levels of exercise in physical training+B when compared to isolated physical training (from 1.3 +/- 0.7 mMol/L versus 2.5 +/- 0.9 mMol/L, (P < 0.05), respectively). CONCLUSION: Physical training associated with BiPAP enhanced the oxidative muscular capacity and could be an adjunctive recourse for physical rehabilitation in patients with chronic obstructive pulmonary disease.

Determination of judo endurance performance using the uchi - komi technique and an adapted lactate minimum test.

This study aimed to evaluate the viability to use Uchi-komi (UK) in the evaluation of the judo endurance performance and using lactate threshold the analysis of the blood lactate ([Lac]) and heart rate (HR) determined through a lactate minimum test. The subjects were a group of 6 male, volunteer judokas, from 25.17 ± 5.76 years old, weight 84.50 ± 23.78 kg and height 1.78 ± 0.10 m, competitors of different levels of performance (from regional to international competitions) and match experience of (11 ± 6) years old. Three tests were performed: a) 3000 m dash in track, b) the adapted test of lactate minimum for running and c) for UK, with execution of the blow ippon-seoi-nague. No significant difference was evident for the track tests and UK in relation to blood lactate and heart rate (p > 0.05) (3.87 ± 0.38 vs 4.17 ± 0.54 mmol·L(-1) and 167 ± 2 vs 152 ± 7 b·min(-1), respectively). In conclusion it is stressed that: 1) The specific test for lactate minimum in judo sport is a promising possibility of aerobic capacity evaluation and a instrument of intensity training control; 2) The metabolic profile in Vlm and UKlm is similar, because there are not differences in the [Lac] and in the HR at this intensity; 3) It is possible to estimate the training intensity through the determination of the lactate minimum intensity in running (Vlm) and the Heart Rate associated (HR) from the execution of ippon-seoi- nague (uchi-komi) in judo training; 4) The Vlm for judo athletes is approximately 88% of the V3000. Key pointsThe specific test for lactate minimum in judo sport is a promising possibility of aerobic capacity evaluation;This is a instrument for intensity training control for judo players;The metabolic profile is similar between running and uki-komi (ippon-seoi-nague techniques) at lactate minimum intensity.

Critical load: a novel approach to determining a sustainable intensity during resistance exercise.

BACKGROUND: A hyperbolic function as well as a linear relationship between power output and time to exhaustion (Tlim) has been consistently observed during dynamic non-resistive exercises. However, little is known about its concept to resistance exercises (RE), which could be defined as critical load (CL). This study aimed to verify the existence of CL during dynamic RE and to verify the number of workbouts necessary to determine the optimal modeling to achieve it. METHODS: Fifteen healthy men (23±2.5 yrs) completed 1 repetition maximum test (1RM) on a leg press and 3 (60%, 75% and 90% of 1RM) or 4 (+ 30% of 1RM) workbouts protocols to obtain the CL by hyperbolic and linear regression models between Tlim and load performed. Blood lactate and leg fatigue were also measured. RESULTS: CL was obtained during RE and 3 workbouts protocol estimate it at 53% while 4 tests at 38% of 1 RM. However, based on coefficients of determination, 3 protocols provided a better fit than the 4-parameter model, respectively (R2>0.95 vs. >0.77). Moreover, all intensities increased blood lactate and leg fatigue, however, when corrected by Tlim, were significantly lower at CL. CONCLUSIONS: It was possible to determinate CL during dynamic lower limbs RE and that 3 exhaustive workbouts can be used to better estimate the CL, constituting a new concept of determining this threshold during dynamic RE and reducing the physically demanding nature of the protocol. These findings may have important applications for functional performance evaluation and prescription of RE programs.

Circuit resistance training in women with normal weight obesity syndrome: body composition, cardiometabolic and echocardiographic parameters, and cardiovascular and skeletal muscle fitness.

BACKGROUND: Normal weight obesity (NWO) syndrome has been characterized in subjects with normal Body Mass Index (BMI) and high body fat mass percentage (BF%>30 for women) being a risk factor for cardiometabolic dysregulation and cardiovascular mortality. This study evaluated whether circuit resistance training (CRT) improves body composition, heart size and function, cardiometabolic parameters, and cardiorespiratory, cardiovascular and skeletal muscle fitness in women with NWO. METHODS: Data are means (95% Confidence Interval). Twenty-three women participated: 10 NWO-CRT (baseline: BMI=22.4 [21.4-23.3] kg/m2; BF%=44.5 [41.0-48.0]%) performed CRT; and 13 untrained NWO-control (baseline: BMI=21.7 [20.8-22.7] kg/m2; BF%=37.8 [34.6-41.1]%). At baseline and after 10 weeks were performed/measured dual-energy X-ray absorptiometry, echocardiography, blood tests, arterial pressure, exercise testing, and total-overload-by-training-session (TOL). RESULTS: At baseline, the NWO-CRT exhibited larger BF (27.28 [23.9-30.6] kg) than NWO-control (22.41 [19.5-25.3] kg) (P=0.0227). After training, NWO-CRT: reduced 8 kg of BF (P=0.000002); became BF% lower than NWO-control (33.1 [30.1-36.0] <37.0 [34.3-39.6]%, P=0.0423), with 30% of NWO-CRT subjects becoming without-obesity; reduced 3 kg in trunk fat mass (P=0.000005); showed fasting glucose (72.8 [69.4-76.2] mg/dL) smaller than NWO-control (81.7 [78.6-84.8] mg/dL) (P=0.004); increased TOL (5087.5 [4142.5-6032.5] to 6963.3 [6226.4-7700.2] rep.kg, P=0.0004); increased load at VO2peak (122.5 [106.8-138.2] to 137.5 [118.18-156.82] W, P=0.0051); reduced double product/load at VO2peak ratio (277.4 [222.1-332.8] to 237.7 [194.2-281.2] mmHg.bpm/W, P=0.0015); and increased left ventricular mass/body surface area ratio (84.29 [78.98-89.6] to 90.29 [81.45-99.12] g/m2, P=0.0215). CONCLUSIONS: CRT reduced BF% and generated cardiometabolic, cardiac, skeletal muscle and cardiovascular benefits, being a useful strategy to combat the normal weight obesity syndrome in women.

Continuous blood pressure response at different intensities in leg press exercise.

BACKGROUND: Generally, the evaluation of the blood pressure response to resistance exercise has been limited to the evaluation of discontinuous casual blood pressure monitoring, often measured at the end of the exercise. DESIGN: To continuously evaluate the blood pressure response at different intensities of leg press exercise with the same duration and number of repetitions. METHODS: Seven normotensive healthy men performed an incremental test on the leg press machine at relative intensities of one repetition maximum (1RM). The blood pressure and heart rate were measured simultaneously to the incremental exercise by a photoplethysmographic method. RESULTS: The mean ± SD peak values of the heart rate, diastolic blood pressure (DBP) and systolic blood pressure (SBP) were obtained on 70% of 1RM and were 145 ± 20 bpm, 113.1 ± 15.4 mmHg, and 192.4 ± 20.0 mmHg, respectively. The SBP was characterized by a decrease followed by an increase during the sets of exercise. The decrease in the SBP was 12-22 mmHg and took approximately 25 seconds to reach the minimum value before the increase. It was observed for all participants in most of the intensities. The rate of increase in the SBP was not statistically different between the intensities. CONCLUSIONS: Both duration and intensity of exercise have an impact on the blood pressure response. Above 30% of 1RM, the SBP decreases in approximately 20 seconds and starts to increase until the end of the set of leg press exercise.

Does aerobic exercise intensity affect health-related parameters in overweight women?

The aim of this study was to compare the effect of a cycling training programme performed at intensity corresponding to the lowest value of the respiratory quotient (RQ) versus at intensity corresponding to the ventilatory threshold (VT), on body composition and health-related parameters in overweight women. Thirty-two sedentary obese women (27-42 years old) were studied in a randomized trial of either RQ (n = 17) or VT (n = 15). RQ and VT training sessions were equalized by time (60 min) and performed in a cycloergometer. Anthropometry, body composition, lipid profile, glucose, basal metabolic rate (BMR) and fitness (maximal oxygen uptake) were evaluated before and after 12 weeks of intervention. Body weight, body mass index, fatness and fitness were improved in both groups (P<0·001). Triglycerides (TG) levels decreased only in response to RQ (P<0·001) and fat-free mass (FFM) to VT (P = 0·002). No differences were observed between groups. Both exercise intensities seem to be effective for improving health in overweight women. However, low-intensity compared with the high-intensity exercise training appears to have additional benefits on TG levels and to maintenance of FFM.

Cardiopulmonary exercise test in type 2 diabetes mellitus in absence of chronic heart failure: reduced lung and heart function / Avaliação cardiopulmonar em portadores de diabetes melitus tipo 2 sem doença cardíaca: redução da função caridorespiratória

Was compared exercise tolerance, respiratory and cardiovascular functions between non--diabetics and type 2 diabetics individuals (T2DM) without chronic heart failure. Thirteen normaglycemic men (non-diabetic group ­ NDG) and eight T2DM (diabetic group ­ DG) performed a cardiopulmonary exercise test (CPX) on motor treadmill (test initiated at 3 km.h-1 with an increment of 1 km.h-1 every two minutes) to evaluate respiratory function, cardiovascular parameters and exercise tolerance. Workload and oxygen uptake ( O2) values at ventilatory threshold were signifi cantly lower for DG (DG: 5.6 ± 0.5 km/h and 13.1 ± 3.8 mL.(kg.min)-1; NDG: 6.5 ± 0.5 km/h and 16.4 ± 2.8 mL.(kg.min)-1; p < 0.05). Peak O2 and workload were signifi cantly lower for DG (22.7 ± 5.7 mL.(kg.min)-1;8.2 ± 0.7 km/h) when compared with NDG (30.8 ± 5.4 mL.(kg.min)-1; 11.6 ± 1.5 km/h). Oxygen uptake effi ciency slope (OUES) and circulatory power were signifi cantly lower (p < 0.05) in DG, although no signifi cant alterations were found in functional capacity and ventilatory effi ciency. T2DM in absence of chronic heart failure presented exercise intolerance and lower cardiorespiratory fi tness. Peak circulatory power and OUES were also reduced in these individuals....(AU)

Foi comparar a tolerância ao exercício, funções respiratória e cardiovascular entre indivíduos não diabéticos e diabéticos tipo 2 sem doenças crônicas cardíacas. Treze homens normoglicêmicos (NDG) e oito homens diabéticos tipo 2 (DG) que realizaram um teste cardiopulmonar de esforço (TCPE) em uma esteira motorizada (o teste iniciou-se em 3km.h-1 com incremento de 1km.h-1 a cada dois minutos) que avaliou a função respiratória, parâmetros cardiovasculares e tolerância ao exercício. Valores de consumo de oxigênio e intensidades na intensidade do limiar ventilatório foram signifi cativamente menores para o DG (DG: 5,6 ± 0,5 km/h-1 e 13,1 ± 3,8 ml.(kg.min)-1; NDG: 6,5 ± 0,5 km/h-1 e 16,4 ± 2,8 ml.(kg.min)-1; p < 0,05). Consumo de oxigênio pico e intensidade associada foram signifi cativamente menores para o DG (DG: 22,7 ± 5,7 ml.(kg.min)-1; 8,2 km/h-1 ± 0,7 km/h-1) quando comparado com o NDG (30,8 ± 5,4 ml.(kg.min)-1; 11,6 ± 1,5 km/h). Oxygen uptake effi ciency slope (OUES) e circulatory power foram signifi cativamente menores para o DG (p < 0,05) embora não foram encontradas diferenças signifi cativas na efi ciência ventilatória. Em indivíduos portadores de diabetes tipo 2, mesmo sem a presença conhecida de doenças cardiovasculares, apresentaram menores níveis de condicionamento cardiorrespiratório e tolerância ao exercício. Circulatory power pico e OUES também foram reduzidos nesses indivíduos....(AU)

Exercise tolerance in rats with aortic stenosis and ventricular diastolic and/or systolic dysfunction.

BACKGROUND: Physical stress tolerance (ST) is a measurement of cardiorespiratory fitness. Aerobic capacity is reduced in heart failure (HF) although there is no data available on this parameter in animals with ventricular dysfunction and no signs of HF. OBJECTIVE: Evaluate ST in rats with ventricular diastolic dysfunction isolated or associated with systolic dysfunction induced by ascending aortic stenosis (AoS). METHODS: Young male Wistar rats (20-30 days old), divided in: control group (CG, n=11) and AoSG group, (n=12). Animals were assessed at 6 and 18 weeks after AoS surgery. Treadmill exercise test was until exhaustion and evaluated treadmill speed and lactate concentration [LAC] at lactate threshold, treadmill speed and [LAC] at exhaustion, and total testing time. RESULTS: Echocardiography data revealed remodeling of the left atrium and left ventricular concentric hypertrophy at 6 and 18 weeks. Endocardial fractional shortening was greater in AoSG than CG at 6 and 18 weeks. Midwall fractional shortening was greater in AoSG than in CG only 6 week. Cardiac index was similar in CG and AoSG at 6 and 18 weeks and decreased between from 6 to 18 weeks in both groups. The E wave to A wave ratio was greater in CG than in AoSG at both periods and did not change in both groups between week 6 and 18. Treadmill stress testing parameters were similar in both groups at 6 or 18 weeks. CONCLUSION: Although AoS promotes isolated diastolic dysfunction or associated with systolic dysfunction at 6 or 18 weeks, it is not sufficient to modify physical stress tolerance.

Effects of ovariectomy and resistance training on oxidative stress markers in the rat liver.

OBJECTIVE: The objective of this study was to assess the effects of resistance training on oxidative stress markers in the livers of ovariectomized rats. METHOD: Adult Sprague-Dawley rats were divided into the following four groups (n = 8 per group): sham-operated sedentary, ovariectomized sedentary, sham-operated resistance training, and ovariectomized resistance training. During the resistance training period, the animals climbed a 1.1-m vertical ladder with weights attached to their tails; the sessions were conducted 3 times per week, with 4-9 climbs and 8-12 dynamic movements per climb. The oxidative stress was assessed by measuring the levels of reduced glutathione and oxidized glutathione, the enzymatic activity of catalase and superoxide dismutase, lipid peroxidation, vitamin E concentrations, and the gene expression of glutathione peroxidase. RESULTS: The results showed significant reductions in the reduced glutathione/oxidized glutathione ratio (4.11±0.65 nmol/g tec), vitamin E concentration (55.36±11.11 nmol/g), and gene expression of glutathione peroxidase (0.49±0.16 arbitrary units) in the livers of ovariectomized rats compared with the livers of unovariectomized animals (5.71±0.71 nmol/g tec, 100.14±10.99 nmol/g, and 1.09±0.54 arbitrary units, respectively). Moreover, resistance training for 10 weeks was not able to reduce the oxidative stress in the livers of ovariectomized rats and induced negative changes in the hepatic anti-oxidative/oxidative balance. CONCLUSION: Our findings indicate that the resistance training program used in this study was not able to attenuate the hepatic oxidative damage caused by ovariectomy and increased the hepatic oxidative stress.