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Ciências do esporte e educação física: Pesquisas científicas inovadoras, interdisciplinares e contextualizadas
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Ischemic preconditioning (IPC) involves brief, repeated bouts of limb occlusion and reperfusion capable of improving exercise performance at least partially by enhancing local skeletal muscle oxygenation. This study sought to investigate the effect of a lower limb IPC protocol, with either a 5-min or 45-min post-application delay, on vastus lateralis tissue saturation index (TSI) and systemic cardiac hemodynamics at rest and during short-duration intense cycling. Twelve young adults randomly completed four interventions: IPC (at 220 mmHg) with 5-min delay (IPC5), IPC with 45-min delay (IPC45), SHAM (at 20 mmHg) with 5-min delay (SHAM5), and SHAM with 45-min delay (SHAM45). Following IPC intervention and recovery delay, participants completed 5, 60-s high-intensity (100% Wpeak) cycle sprints separated by 120-sec of active recovery (30% Wpeak). Compared to baseline, TSI immediately following IPC5, but pre-exercise, remained lower than the equivalent for IPC45 (-5.9 ± 1.5%, p= .002). IPC, imposed at least 45-min before the completion of five 60-s sprint cycling efforts, significantly enhanced TSI during active recovery between sprint intervals compared to a 5-min delay (6.6 ± 2.4%, p= .021), and identical SHAM conditions (SHAM5: 5.8 ± 2.2%, p= .024; SHAM45: 6.2 ± 2.5%, p= .029). A 45-min delay following IPC appears to provide heightened skeletal muscle metabolic rebound prior to intense sprint cycling as compared to a 5-min delay. Furthermore, IPC followed by a 45-min delay enhanced recovery of skeletal muscle oxygenation during low intensity active sprint recovery, despite an unchanged decline in skeletal muscle oxygenation during near-maximal sprinting efforts.
This study examined the effects of a simultaneous ischemic preconditioning (IPC) and SHAM intervention to reduce the placebo effect due to a priori expectation on the performance of knee extension resistance exercise. Nine moderately trained men were tested in three different occasions. Following the baseline tests, subjects performed a first set of leg extension tests after the IPC (3 X 5 min 50 mmHg above systolic blood pressure) on right thigh and the SHAM (same as IPC, but 20 mmHg) on left thigh. After 48 hours, the subjects performed another set of tests with the opposite applications. Number of repetitions, maximal voluntary isometric contraction (MVIC) and perceptual indicators were analyzed. After IPC and SHAM intervention performed at the same time, similar results were observed for the number of repetitions, with no significant differences between conditions (baseline x IPC x SHAM) for either left (p = 0.274) or right thigh (p = 0.242). The fatigue index and volume load did not show significant effect size after IPC and SHAM maneuvers. In contrast, significant reduction on left tight MVIC was observed (p = 0.001) in SHAM and IPC compared to baseline, but not for right thigh (p = 0.106). Results from the current study may indicate that applying IPC prior to a set of leg extension does not result in ergogenic effects. The placebo effect seems to be related to this technique and its dissociation seems unlikely, therefore including a SHAM or placebo group in IPC studies is strongly recommended.
Ischemic preconditioning (IPC) has been repeatedly reported to augment maximal exercise performance over a range of exercise durations and modalities. However, an examination of the relevant literature indicates that the reproducibility and robustness of ergogenic responses to this technique are variable, confounding expectations about the magnitude of its effects. Considerable variability among study methodologies may contribute to the equivocal responses to IPC. This review focuses on the wide range of methodologies used in IPC research, and how such variability likely confounds interpretation of the interactions of IPC and exercise. Several avenues are recommended to improve IPC methodological consistency, which should facilitate a future consensus about optimizing the IPC protocol, including due consideration of factors such as: location of the stimulus, the time between treatment and exercise, individualized tourniquet pressures and standardized tourniquet physical characteristics, and the incorporation of proper placebo treatments into future study designs.
This study investigated the efficacy of ischemic preconditioning (IPC) on the recovery of maximal aerobic performance and physiological responses compared with commonly used techniques. Nine endurance athletes performed two 5-km cycling time trials (TT) interspersed by 45 minutes of recovery that included either IPC, active recovery (AR) or neuromuscular electrical stimulation (NMES) in a randomized crossover design. Performance, blood markers, arterial O2 saturation (SpO2), heart rate (HR), near-infrared spectroscopy-derived muscle oxygenation parameters and perceptual measures were recorded throughout TTs and recovery. Differences were analyzed using repeated-measures ANOVAs and Cohen's effect size (ES). The decrement in chronometric performance from TT1 to TT2 was similar between recovery modalities (IPC: -6.1 sec, AR: -7.9 sec, NMES: -5.4 sec, p = 0.84, ES 0.05). The modalities induced similar increases in blood volume before the start of TT2 (IPC: 13.3%, AR: 14.6%, NMES: 15.0%, p = 0.79, ES 0.06) and similar changes in lactate concentration and pH. There were negligible differences between conditions in bicarbonate concentration, base excess of blood and total concentration of carbon dioxide, and no difference in SpO2, HR and muscle O2 extraction during exercise (all p > 0.05). We interpreted these findings to suggest that IPC is as effective as AR and NMES to enhance muscle blood volume, metabolic by-products clearance and maximal endurance performance. IPC could therefore complement the athlete's toolbox to promote recovery.
A seriedade da proposta de um Curso de Graduação no Ensino Superior se revela na qualidade dos profissionais que ela coloca no mercado de trabalho, fruto da dedicação e competência dos professores que compõe o quadro docente dessa IES. Para que isso ocorra, é necessário que haja uma cumplicidade entre todos os envolvidos no processo diante dos desafios comuns que se enfrentam nas mais diversas histórias e trajetórias de cada um envolvido nesse processo todo, porém, mais ainda, das grandes possibilidades vislumbradas em cada segmento de atuação escolhido, e, nesse caso específico da coletânea que se apresenta nesse momento, a nossa amada Educação Física. Os textos contidos nessa Coletânea são o resultado dos Trabalhos de Conclusão de Curso de diversos ex-alunos que tive a felicidade de tê-los, uma hora ou outra, em minha sala de aula, nas diversas disciplinas que há 26 anos eu trabalho no Curso de Educação Física, exclusivamente no Ensino Superior. Os temas aqui abordados situam-se nas mais diversas áreas de abrangência e atuação da Educação Física e correspondem à preocupação de seus respectivos autores e orientadores em buscar resposta ao problema que outrora lhes serviram de “start” para os textos que hoje fazem parte desta obra. Entendo que a “sala de aula” se trata de um universo amplo e diversificado de incontável variáveis, porém, o somatório de experiências que nesse espaço confluem, têm se revelado serem elementos essenciais no estabelecimento de diretrizes pedagógicas que só enaltecem o processo de ensino-aprendizagem. Me sinto realizado como Organizador dessa Coletânea por dois motivos: o primeiro deles se deve à publicação de um texto em parceria com meu filho Luiz Guilherme, hoje, acadêmico do Curso de Bacharelado em Educação Física e, o segundo, por ter como parceiro de organização dessa obra, um ex-acadêmico da Graduação em Licenciatura e Bacharelado em Educação Física e ex-aluno da Pós-Graduação, hoje, meu amigo e colega de profissão na mesma IES, Prof. Walderson Nunes de Freitas. Essa Coletânea está dividida, contextualmente, em seis seções distintas que fazem parte intrinsecamente da Educação Física, sendo estas (a) Esporte, Cultura e Sociedade; (b) Exercício Físico, Qualidade de Vida e Melhor Idade; (c) Esportes e Treinamento Desportivo; (d) Educação Física Escolar; (e) Academia, Fitness e Wellness; (f) Exercício Físico, Qualidade de Vida e Saúde.
Background
The effects of ischemic preconditioning (IPC) versus a deceptive sham protocol on indirect markers of exercise-induced muscle damage (EIMD) after the application of individualized occlusion pressure were examined. The goal of using a sham protocol is to control for the potential effect of placebo.
Hypothesis
IPC would surpass the sham protocol in protecting against EIMD.
Study Design
A randomized, double-blinded, clinical trial.
Level of Evidence
Level 1.
Methods
Thirty healthy young men were randomly assigned to an eccentric exercise for the knee extensor muscles preceded by IPC (4 × 5 minutes of individualized total occlusion pressure) or sham protocol (4 × 5 minutes using 20 mm Hg). Maximal voluntary isometric torque (MVIT), rate of torque development, muscle soreness, pressure pain threshold, knee range of motion, thigh girth, and creatine kinase (CK) activity were assessed before IPC or sham protocol and up to 72 hours after the eccentric EIMD. Affective valence and perceived exertion were also evaluated.
Results
MVIT decreased 17.1% in the IPC and 18.1% in the sham groups, with no differences between groups. Differences from baseline were observed in the sham group for muscle soreness at 48 hours ( P < 0.001) and 72 hours ( P = 0.02), and for CK activity at 72 hours ( P = 0.04). Muscle soreness was reduced in the IPC group at 48 hours compared with the sham group (∆ = 15.8 mm; P = 0.008) but without achieving the minimal clinically important difference. IPC induced a smaller perceived exertion than the sham protocol (∆ = 1.1 a.u.; P = 0.02). The remaining outcomes were not statistically different in both groups.
Conclusion
IPC does not surpass the sham protocol to protect against mild EIMD of the knee extensors muscles.
Clinical Relevance
Although IPC is a noninvasive, low-cost, and easy-to-administer intervention, the IPC effects can, in part, be explained by the placebo effect. In addition, individualized IPC promotes attenuation in perceived exertion during eccentric exercise.
Psychological responses are important considerations for exercise adherence. A large body of evidence indicates that exercise intensity is a controllable variable capable of increasing positive feelings. Investigations thus far, however, have not considered that the higher incidence of negative psychological responses, physical inactivity and dropout rates in women could be due to physiological particularities of the menstrual cycle (MC). This project investigates the effect of MC phases and exercise intensity on psychophysiological responses in fourteen healthy, eumenorrheic and physically active women. Measuring psychophysiological responses before, during and after exercise, participants completed two exercise bouts of 15 minutes above and below the anaerobic threshold in the follicular phase (FP) and the luteal phase (LP) of the MC. Lower levels of depression and hostility and higher levels of vigor, affect and motivation were observed during exercise in the FP. Exercise at moderate intensity elicited better psychological responses compared to high intensity exercise, highlighted by findings that affect and rating of perceived exertion were worse in the LP without changes in physiological responses. These findings suggest no effect of MC on physiological responses, but psychological responses are impaired in the LP, worsening particularly during exercise at high intensity.
Halley, SL, Peeling, P, Brown, H, Sim, M, Mallabone, J, Dawson, B, and Binnie, MJ. Repeat application of ischemic preconditioning improves maximal 1,000-m kayak ergometer performance in a simulated competition format. J Strength Cond Res XX(X): 000-000, 2020-This study examined the effects of ischemic preconditioning (IPC) on repeat 1,000-m kayak ergometer time-trial (TT) performance, completed in a simulated competition format. Eight well-trained male kayak athletes performed 3 experimental trials, each consisting of two 1,000-m TTs separated by 80 minutes (TT 1 and TT 2). Trials included; (a) IPC (4 × 5 minutes 220 mm Hg alternating bilateral leg occlusion) 40 minutes before TT 1 only (IPC1); (b) IPC 40 minutes before TT 1 and 20 minutes before TT 2 (IPC2); and (c) no IPC (CON). Time, power, stroke rate, and expired gas variables (V[Combining Dot Above]O2 and accumulated oxygen deficit) were measured throughout each TT; blood gas variables (blood lactate, partial pressure of oxygen and blood pH) and rating of perceived exertion were measured before and after each effort. Physiological, perceptual, and physical measures were analyzed via a repeated measures analysis of variance with the level of significance set at p ≤ 0.05. There were large improvements in completion time for TT 1 in IPC1 (d = 1.24 ± 0.68, p < 0.05) and IPC2 (d = 1.53 ± 0.99, p < 0.05) versus CON. There was also a large improvement in TT 2 completion time in IPC2 versus CON (d = 1.26 ± 1.13, p = 0.03) whereas, IPC1 and CON were indifferent (d = 0.3 ± 0.54, p = 0.23). This study showed that a repeat application of IPC in a simulated competition format may offer further benefit in comparison to a single pre-exercise application of IPC.
