Gustavo Soares Pereira

The time dependence of the effect of ischemic preconditioning on successive sprint swimming performance

OBJECTIVES The present study aimed to determine the effects of ischemic preconditioning on performance in three successive 50-m swimming trials and to measure stroke rate, stroke length and blood lactate accumulation. DESIGN Counterbalanced, repeated-measures cross-over study. METHODS On two separate days, eleven competitive male swimmers (20±3 years, 182±5cm, 77±5kg) performed three successive 50-m trials in a 50-m swimming pool, preceded by intermittent bilateral cuff inflation (4× 5-min of blood flow restriction+5-min of cuff deflation) at either 220 for thighs and 180mmHg for arms (ischemic preconditioning) or 20mmHg for both limbs (control-treatment). The 50-m trials were conducted 1-, 2-, and 8-h after the procedure. RESULTS While no ergogenic effect of ischemic preconditioning was observed for 1-h (0.4%, 95% confidence limits of ±0.6%, p=0.215), there were clear beneficial effects of ischemic preconditioning on 2- and 8-h (1.0% and 1.2%, respectively; 95% confidence limits of ±0.6% in both cases, p≤0.002). Furthermore, ischemic preconditioning increased blood lactate accumulation in 2-(p<0.001) and 8-h (p=0.010) and stroke rate for 2- and 8-h in specific 10-m segments (p<0.05). CONCLUSIONS These findings suggest a time-dependent effect of ischemic preconditioning on 50-m swimming performance for competitive athletes, with the time window of the beneficial effect starting after about 2-h and lasting for at least 8-h after ischemic preconditioning. This change in performance was accompanied by an increase in blood lactate accumulation and faster strokes in front crawl.

ATIVIDADE FÍSICA E QUALIDADE DE VIDA EM MULHERES COM CÂNCER DE MAMA - UM ESTUDO TRANSVERSAL

Rev Bras Med Esporte – Vol. 24, No 5 – Set/Out, 2018 ABSTRACT Introduction: Breast cancer treatment can cause different side effects on the quality of life of women. Physical activity, in turn, can reduce these side effects. Objective: To investigate the physical activity and quality of life of women during and after breast cancer treatment. Methods: Sample of 174 women (57.0±9.5 years) during or after clinical treatment for breast cancer. Interview questionnaire composed of general information, physical activity (IPAQ short version) and quality of life (EORTC QLQ-C30 and BR23). For statistical analysis chi-squared test or Fisher’s exact test, student’s t-test for independent samples, Mann-Whitney U test and multiple logistic regression analyses (p <0.05). Results: Most women did not achieve the physical activity guidelines, particularly those undergoing clinical treatment. Results showed longer walking time, moderate physical activity, vigorous physical activity, moderate + vigorous physical activity, and total physical activity among the women following completion of treatment. The quality of life scores were also higher among women after clinical treatment. Logistic regression indicated that every 10-minute increment to walking time results in a 19% decrease in the probability of worse functional capacity and a 26% decrease in the probability of worse symptoms associated with treatment side effects. Conclusion: During treatment, women with breast cancer undertake less physical activity and have worse quality of life. Walking appears to be an effective type of physical activity for these women, improving quality of life during and after breast cancer treatment. Level of evidence II; Prognostic studies Investigation of the effect of patient characteristics on the disease outcome.

Vertical ground reaction force in stationary running in water and on land: A study with a wide range of cadences

PURPOSE The aim of this study was to analyze the effect of cadence, immersion level as well as body density on the vertical component (Fymax) of ground reaction force (GRF) during stationary running (SR). METHODS In a controlled, laboratory study, thirty-two subjects ran at a wide range of cadences (85-210 steps/min) in water, immersed to the hip and to the chest, and on dry land. Fymax. was verified by a waterproof force measurement system and predicted based on a statistical model including cadence, immersion ratio and body density. RESULTS The effect of cadence was shown to depend on the environment: while Fymax increases linearly with increasing cadence on land; in water, Fymax reaches a plateau at both hip and chest immersions. All factors analyzed, cadence, immersion level and body density affected Fymax significantly, with immersion (aquatic × land environment) showing the greatest effect. In water, different cadences may lead to bigger changes in Fymax than the changes obtained by moving subjects from hip to chest immersion. A regression model able to predict 69% of Fymax variability in water was proposed and validated. CONCLUSION Cadence, Immersion and body density affect Fymax in a significant and non-independent way. Besides a model of potential use in the prescription of stationary running in water, our analysis provides insights into the different responses of GRF to changes in exercise parameters between land and aquatic environment.

Hand force symmetry during breaststroke swimming

Hand force symmetry during breaststroke swimming The aim of this study was to analyze the hand force symmetry during the breaststroke and its relationship with swimmers’ performance. Seventeen breaststroke and/or medley specialists participated (12 men and 5 women, 19.5 ± 5.2 years and average performance of 73.4 ± 7% of the 50 m breaststroke world record). Each swimmer performed three repetitions of 25 m breaststroke swimming at maximal speed. Pressure sensors from Aquanex acquisition system were placed in both swimmers’ hands and Mean Force (Fmean) and Maximal Force (Fmax) were measured. The symmetry index proposed by Sanders was calculated and the time of a 50-m breaststroke trial at maximum speed (T50m) was used as a performance indicator. The variables were compared between hands using tests for dependent samples, and the relationship between variables were investigated using Spearman correlation test. The Fmean applied was 47.9 ± 16.7 N and 47.9 ± 14.5 N for right and left hands, respectively. The Fmean corresponded to 120.7 ± 43.6 N e 112.8 ± 35.7 N for right and left hand, respectively. No signifi cant differences were observed for none of the variables between right and left hands. Analyzing the subjects individually, it was possible to observe asymmetries levels up to 30.6% for Fmean and 35.9% for Fmax, however the relationship between symmetry indexes and the 50 m breaststroke performance was not statistically signifi cant.