Swimming rats’ model: influence of age and density on the maximal lactate steady state test

The aim of this study was to verify wether the density plays a significant role in the swimming model for rats. To verify such possibility the rats’ weight in the water was considered as an additional workload beyond the load increment. Forty Wistar rats divided in groups of 90, 120 and 210 days old were used. The animals had their hydrostatic weight and density determined by an apparatus for water weighing. Later, all the rats were evaluated at the maximal lactate steady state (MLSS) test adapted for swimming rats. Statistic Analysis was performed by Anova one-way and Scheffé post hoc test (p\u3c0.05). Results showed hydrostatic weight (g) and density (g/cm3) of 10.2 and 0.997, 16.8 and 1.011, 21.4 and 1.017 for G90, G120 and G210, respectively, with significant differences between ages. Blood lactate concentrations at the MLSS were 4.1, 4.8 and 5.5 mmol/L for G90, G120 and G210, respectively and were not significantly different; but it showed a trend to increase in agreement with the presented ages. In contrast, the workloads seemed to decrease with age in the conventional method (5.3, 4.7, 4.5% of body weight for G90, G120 and G210, respectively), however when the hydrostatic weight was considered, an increase in effort was found in agreement with age (7.9, 8.4, 8.5% of body weight for G90, G120 and G210, respectively). This fact could be an explanation for the higher lactate concentration found in older groups. So, it is possible to suggest that in the convencional workload method the 210 days group has its aerobic capacity underestimated because these rats are denser than those 90 days animals

Reproducibility of the lactate minimum test in wistar rats after training at the maximal lactate steady state intensity

The aim of this study was to verify the reproducibility of the lactate minim (LM) test after four weeks of aerobic training, as well as its validity with the maximal lactate steady state (MLSS) in Wistar rats submitted to swimming exercise. Ten rats with 90 days were used. The aerobic and anaerobic capacity was determined by the LM test before and after the training. The protocol of MLSS was also applied before and after the training. Training was accomplished for four weeks, being the first two weeks with a volume of 30 minutes and the other two weeks with a volume of 45 minutes, both in the intensity of MLSS. With the training, the intensity of LM and the concentration of LM [Lac] increased of 16.19±1.87 to 18.84 ± 0.96 g and of 3.58±1.78 to 5.42±1.13 mmol/L, respectively. The intensity of MLSS increased of 18.64±1.75 to 19.97±2.15 g. The intensity of LM and MLSS in the pre and post-training phase presented high correlations (r=0.92) and (r=0.87), respectively. It was concluded that the LM test presented sensibility to the effects of the training, as well as validity with gold standard test (MLSS) in rats submitted to swimming exercise

Determination of critical power using a straight bench press with a test protocol

The purpose of this study was to investigate the validity of critical force test from maximal lactate steady state (MLSS) during resistance test using straight bench press (SBP). Five healthy male volunteers aged (22.6 ± 2.88 years), weight (76.3 ± 11.49 kg) e height (182.6 ± 7.54 cm), trained in resistance exercise, performed four diferent tests to determine: one maximal effort (1RM), critical force using the critical power model (force vs 1/time limit – 20.25 and 30% of 1RM). The CF was the linear coefficient and the anaerobic impulse capacity (CIA) was the angular. MLSS was determined using loads of 80, 90, 100 and 110% of critical force. Blood lactate samples were abtained at each 300sec between each stage of total 1200sec. Maximal 30s test (M30) was accomplished with load of 25% of body weight in SBP. The results showed that the 1 RM was 79.4 Kgf (± 16.98), CF 10.1N (± 2.25), CIA 1756.82 N.s (± 546.96) and the R² 0.984 (± 0.02). The MLSS occurs at 100% CF load. The lactate concentration at the MLSS was 2.2 mmol/L (± 0.77). Significant correlation was observed between MLSS and CF on SBP (r = 0.88, p = 0.05). In M30 the minimum, mean and peak power were (25.0 ± 4.9, 28.0 ± 4.9, and 30.0 ± 4.6 kgf.rps, respectively). The fatigue index was 18.0% (± 6.8). The M30 was significantly correlated with Ppeak and Pmean (r = 0.98 for both, p = 0.003). The CF means has been validated to predict the resistance training and the CIA, showing to be a representative anaerobic parameter in straight bench press

Influence of the pedaling cadence in determining the critical power in the cycloergometer

The objective of this study was to determine the critical power (PCrit) using intensities of 230, 250, 270 and 300 Watts (W) under different speeds ranging from pedaling (60 and 80 rotations per minute - rpm). Two young adults, male, healthy and active, with an average age 22 years were selected. The test was conducted in cycle model Monark® ergomedic 894 E. The depth charges were chosen randomly, changing the relationship load and speed from the cadence. The exhaustion criterion was the voluntary withdrawal or failure to maintain the speed for 5 seconds. To determine the PCrit and anaerobic work capacity (CTA) the linear model of power 1/tempo x exhaustion was used. The results are expressed as mean ± standard deviation of the mean. The t Student test for independent samples for comparison PCrit CTA and the cadences of 60 and 80 rpm was used. During the tests the heart rate (bpm) every 15 seconds was recorded. The results of PCrit to 60 rpm (Pcrit60rpm) and PCrit at 80 rpm (Pcrit80rpm) were not statistically different (Pcrit60rpm=208.1±12.0 W and Pcrit80rpm=165.5±33.2 W). The average Pcrit60rpm was 25% higher than Pcrit80rpm. The absolute values of CTA were not different (CTA60rpm=10316.6±3766.7, CTA80rpm=15996.5±5247.4). The CTA80rpm was 55% higher compared to CTA60rpm. Thus, one can conclude that the cadence of pedaling at 60 rpm and 80 did not statistically influence the values of PCrit and CAT. However, the percentage of Pcrit80rpm was significantly below Pcrit60rpm

Effect of cadence to determine critical power using non- exhaustive protocol in cycle ergometer

In cycling the exercise power (w) is a product of cadence (rpm) and kilopounds (kp). The purpose of this study was to check the pedaling frequency influence on critical power (CP) determined using non-exhaustive aerobic capacity test (Chassain, 1986). Adult men (n=2) were submitted to four powers (100, 120, 130 and 150 w) in two different cadences (40 and 70 rpm) in cycloergometer (Monark 894 E). Two exercise bouts lasting 180 seconds by 90 seconds of interval were performed at an equal intensity. For each intensity, delta heart rate (ΔHR) was determined by subtraction of the maximum heart rate (MHR) at the end of the first effort from the MHR at the end of the second effort (ΔHR= MHR 2 – MHR 1). Individual linear interpolation of ΔHR enabled determination of a null Δ equivalent to the CP. The mean value of CP at 70 rpm was 83.8 ± 22.5 W while the CP at 40 rpm was 100.2 ± 8.4 Watts. The mean value of CP at 40 rpm was 17% higher than at 70 rpm. The cadence can be decisive to determine the CP using non-exhaustive protocol

Short and long term effects of high-intensity interval training on hormones, metabolites, antioxidant system, glycogen concentration, and aerobic performance adaptations in rats

The purpose of the study was to investigate the effects of short and long term High-Intensity Interval Training (HIIT) on anaerobic and aerobic performance, creatinine, uric acid, urea, creatine kinase, lactate dehydrogenase, catalase, superoxide dismutase, testosterone, corticosterone, and glycogen concentration (liver, soleus, and gastrocnemius). The Wistar rats were separated in two groups: HIIT and sedentary/control (CT). The lactate minimum (LM) was used to evaluate the aerobic and anaerobic performance (AP) (Baseline, 6, and 12 weeks). The lactate peak determination consisted of two swim bouts at 13% of body weight (bw): (1) 30 s of effort; (2) 30 s of passive recovery; (3) exercise until exhaustion (AP). Tethered loads equivalent to 3.5, 4.0, 4.5, 5.0, 5.5, and 6.5% bw were performed in incremental phase. The aerobic capacity in HIIT group increased after 12 weeks (5.2 +/- 0.2% bw) in relation to Baseline (4.4 +/- 0.2% low), but not after 6 weeks (4.5 +/- 0.3% bw). The exhaustion time in HIIT group showed higher values than CT after 6 (HIIT = 58 +/- 5 s; CT = 40 +/- 7 s) and 12 weeks (HIIT = 62 +/- 7 s; CT = 49 +/- 3 s). Glycogen (mg/100 mg) increased in gastrocnemius for HIIT group after 6 weeks (0.757 +/- 0.076) and 12 weeks (1.014 +/- 0.157) in comparison to Baseline (0.358 +/- 0.024). In soleus, the HIIT increased glycogen after 6 weeks (0.738 +/- 0.057) and 12 weeks (0.709 +/- 0.085) in comparison to Baseline (0.417 +/- 0.035). The glycogen in liver increased after HIIT 12 weeks (4.079 +/- 0.319) in relation to Baseline (2.400 +/- 0.416). The corticosterone (ng/mL) in HIIT increased after 6 weeks (529.0 +/- 30.5) and reduced after 12 weeks (153.6 +/- 14.5) in comparison to Baseline (370.0 +/- 18.3). In conclusion, long term HIIT enhanced the aerobic capacity, but short term was not enough to cause aerobic adaptations. The anaerobic performance increased in HIIT short and long term compared with CT, without differences between HIIT short and long term. Furthermore, the glycogen super-compensation increased after short and long term HIIT in comparison to Baseline and CT group. The corticosterone increased after 6 weeks, but reduces after 12 weeks. No significant alterations were observed in urea, uric acid, testosterone, catalase, superoxide dismutase, sulfhydryl groups, and creatine kinase in HIIT group in relation to Baseline and CT7FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP04/01205-6; 06/58411-

Acute effect of exercise in the maximal lactate steady state intensity on protein and mRNA expressions of HIF-1a, MCTs 1 and 4, PGC-1a, in heart, liver and skeletal muscle of swimming rats

Orientador: Claudio Alexandre GobattoTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Educação FísicaResumo: Sabe-se que o estresse físico exerce uma função moduladora na expressão gênica dos MCTs 1 e 4 por meio de vias de sinalização moleculares aparentemente distintas envolvendo o co-ativador-1 'alfa' do receptor gama ativado por proliferador do peroxissomo (PGC-1?) e subunidade 1 'alfa' do fator induzível por hipóxia (HIF-1?) respectivamente. Apenas uma única sessão de exercício de resistência (endurance) está associada ao aumento na expressão do MCT1 e PGC-1?, mas não do MCT4, no músculo esquelético vasto lateral de humanos, enquanto o exercício intermitente de alta intensidade parece afetar ambos MCTs 1 e 4 além do PGC-1?. No entanto pouco se conhece sobre o efeito simultâneo do estresse físico sobre o HIF-1?, MCts 1 e 4 e PGC-1? em diferentes tecidos e tipos de fibra. É provável que tanto a expressão quanto a transcrição dos co-ativadores e fatores de transcrição envolvidos na modulação dos MCTs 1 e 4 frente ao estresse físico sejam afetadas pelas características da atividade e ainda variem de acordo com o tipo e especificidade do tecido analisado. Dessa forma, o objetivo desse estudo foi verificar o efeito agudo de uma única sessão de natação até exaustão ou de 30 minutos contínuos ou 25 minutos acumulados intermitentemente, em uma intensidade equivalente ou 20% superior a máxima fase estável de lactato, sobre a expressão gênica e conteúdo protéico dos HIF-1?, MCTs 1 e 4, PGC-1?, imediatamente, 2, 4 e 8 horas após a sessão de exercício, em tecidos chaves para metabolismo do lactato (fibras esqueléticas I e II, fígado, coração) de ratos. O exercício físico aumenta a expressão proteica e mRNA em relação ao grupo controle para maior parte dos genes que foram analisados, porém, não há diferenças entre os grupos exercitados independente do tecido e do protocolo utilizado. Com exceção do tecido hepático cuja apenas a expressão de PGC-1? mRNA é estimulada, uma única sessão de exercício induz diferentes respostas ao longo de 8 horas na expressão mRNA e conteúdo de HIF-1?, MCTs 1 e 4, PGC-1?. Uma sessão contínua de volume reduzido ou uma sessão intermitente em intensidade 20% superior a MFEL, resultam nas mesmas adaptações de uma sessão contínua de 30 minutos de duração em intensidade equivalente a MFELAbstract: It is known that physical stress plays a role on regulating the gene expression of MCTs 1 and 4 by distinct molecular signaling pathways involving the peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PGC-1?) and hypoxia inducible factor 1 alpha subunit (HIF-1?) respectively. Only a single endurance session is associated with increased expression of both PGC-1? and MCT1, but not of the MCT4 in the muscle vastus lateralis of humans, while the intermittent exercise of high intensity seems to affect, besides the PGC-1?, both MCTs 1 and 4. However, the knowledge about the simultaneously effect of the exercise stress on the HIF-1?, MCTs 1 and 4 and PGC-1? in different types of tissues and skeletal muscles is unknow. Probably, the transcription factors and the coativators involved in the exercise induced modulation of MCTs 1 and 4 can being differently affected by the exercise intensity and may vary according to the type and metabolic specificity of the tissue. Thus, the aim of this study was to investigate the acute effect of a single swimming session of 30 continuous minutes or 25 minutes accumulated intermittently or until exhaustion in the intensity equivalent or 20% higher than the maximum lactate steady state (MLSS), on the gene expression and protein content of HIF-1?, MCTs 1 and 4, PGC-1?, immediately, 2, 4 and 8 hours after, in key tissues to the lactate metabolism (skeletal muscle of type I and II, liver, heart) of rats. Physical exercise increased protein content and mRNA expression for most of the analyzed genes, however, there are no differences between the exercised groups independently of the tissue or protocol used. With the exception to liver, where only PGC-1? mRNA was stimulated, a single exercise bout induced different responses throughout 8 hours on mRNA expression and content of HIF-1?, MCTs 1 and 4, PGC-1?. Both, continuous or intermittent exercise, of reduced volume and in higher intensity (20%) results in similar responses of a continuous session of 30 minutes duration in the MLSS intensityDoutoradoBiodinamica do Movimento e EsporteDoutor em Educação Físic

Physiological, psychological and biomechanical parameters applied in canoe slalom training: a review

Canoe slalom is an Olympic sport held in natural and artificial rivers, with peculiar characteristics as compared to other sports. This sport is divided into the subdisciplines of kayak single (K1), canoe single (C1) and canoe double (C2), which also have specific characteristics. As with many other Olympic sports still on the rise, which lack expressive media recognition, few scientific studies have investigated canoe slalom. This information gap minimises possible similarities between theory and practice and advances in the preparation of teams (i.e., coaches, physical trainers and athletes). It is well established that for athletic development, several areas of knowledge must be integrated and applied to the specific nature of the sport, optimising sports training and athletic performance. Accordingly, this review aims to bring together studies on the physiological, psychological and biomechanical parameters, sports strategies and periodisation training applied to canoe slalom, explaining the need for increased knowledge in each of these areas of the practice of this sport1412441CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP472277/2011-12012/06355-2; 2009/08535-