Agreement between Different Methods to Measure the Active Drag Coefficient in Front-Crawl Swimming.

The aim of this study was to analyze the agreement of the active drag coefficient measured through drag and propulsion methods. The sample was composed of 18 swimmers (nine boys: 15.9 ± 0.9 years; nine girls: 15.3 ± 1.2 years) recruited from a national swimming team. The velocity perturbation method was used as the drag measurement system and the Aquanex system as the propulsion system. For both sexes combined, the frontal surface area was 0.1128 ± 0.016 m2, swim velocity 1.54 ± 0.13 m.s-1, active drag 62.81 ± 11.37 N, propulsion 68.81 ± 12.41 N. The level of the active drag coefficient agreement was calculated based on the mean values comparison, simple linear regression, and Bland Altman plots. The mean data comparison revealed non-significant differences (p > 0.05) between methods to measure the active drag coefficient. Both the linear regression (R2 = 0.82, p < 0.001) and Bland Altman plots revealed a very high agreement. The active drag coefficient should be the main outcome used in the interpretation of the swimmers' hydrodynamic profile, because it is less sensitive to swimming velocity. Coaches and researchers should be aware that the active drag coefficient can also be calculated based on propulsion methods and not just based on drag methods. Thus, the swimming community can now use different equipment to measure the hydrodynamics of their swimmers.

Physiological and Perceptual Responses to Aerobic Exercise With and Without Blood Flow Restriction.

ABSTRACT: Silva, JCG, Domingos-Gomes, JR, Freitas, EDS, Neto, GR, Aniceto, RR, Bemben, MG, Lima-dos-Santos, A, and Cirilo-Sousa, MS. Physiological and perceptual responses to aerobic exercise with and without blood flow restriction. J Strength Cond Res 35(9): 2479-2485, 2021-Although previous studies have demonstrated the potential benefits of aerobic exercise (AE) with blood flow restriction (BFR), these findings have been limited by the approaches used to determine the occlusive pressure. In addition, the physiological and perceptual responses of AE with BFR compared to high-intensity interval exercise (HIIE) remain unclear. Thus, we investigated the physiological and perceptual responses to AE with and without BFR, and HIIE. Twenty-two men were randomly assigned to 4 experimental conditions: AE (40% of maximal oxygen consumption [V˙o2peak]), AE with 50% of BFR (AE-BFR: 40% VV˙o2peak), HIIE (80% V˙o2peak), and a no exercise control condition (CON: 50% of BFR). Each exercise bout lasted 18 minutes, during which oxygen consumption (V˙o2), heart rate (HR), and ratings of perceived exertion (RPE) were measured at rest and at every 3 minutes during exercise. Ratings of discomfort before and after each trial. The HIIE condition induced the greatest increases in V˙o2 and HR (p < 0.05), whereas AE-BFR was significantly (p < 0.05) greater than AE and CON. HIIE and AE-BFR also elicited the greatest (p < 0.05), but similar (p > 0.05), increases in RPE during exercise, although AE-BFR was significantly greater than HIIE immediately after exercise (p < 0.05). AE-BFR and HIIE also induced similar levels of discomfort after exercise (p > 0.05). In conclusion, HIIE induced the greatest increases in V˙o2 and HR, although the perceptual responses were essentially the same compared with AE-BFR. However, albeit inferior to HIIE, V˙o2 was greater during AE-BFR compared with AE, indicating that this training method may be used to replace HIIE and still significantly elevate V˙o2.

Acute and Chronic Responses of Aerobic Exercise With Blood Flow Restriction: A Systematic Review.

This study systematically reviewed the available scientific evidence pertaining to the acute and chronic changes promoted by aerobic exercise (AE) combined with blood flow restriction (BFR) on neuromuscular, metabolic and hemodynamic variables. PubMed, Web of ScienceTM and Scopus databases were searched for the period from January 2000 to June 2019 and the analysis involved a critical content review. A total of 313 articles were identified, of which 271 were excluded and 35 satisfied the inclusion criteria. Twelve studies evaluated the acute effects and eight studies evaluated the chronic metabolic effects of AE + BFR. For the neuromuscular variables, three studies analyzed the acute effects of AE + BFR and nine studies analyzed the chronic effects. Only 15 studies were identified that evaluated the hemodynamic acute effects of AE + BFR. The analysis provided evidence that AE combined with BFR promotes positive acute and chronic changes in neuromuscular and metabolic variables, a greater elevation in hemodynamic variables than exercise alone, and a higher energy demand during and after exercise. Since these alterations were all well-tolerated, this method can be considered to be safe and feasible for populations of athletes, healthy young, obese, and elderly individuals.

Are there differences in the activation of the agonist and antagonist muscles during resistance training sessions with continuous or intermittent blood flow restriction? / Existem diferenças na ativação dos músculos agonista e antagonista durante sessões de treinamento de força com restrição de fluxo sanguíneo contínua ou intermitente?

Resistance training (RT) with blood flow restriction (BFR) has been used to increase muscle strength and hypertrophy, however, the best strategy to perform BFR (continuous or intermittent) has not yet been established. The aim of this study was to analyze the chronic effect of RT with continuous or intermittent blood flow restriction (CBFR or IBFR) on muscle activation. A total of 24 men with RT experience were randomly divided into three experimental groups: low-load exercises at 20% of one repetition maximum (1RM) combined with CBFR (LL + CBFR), low-load exercises at 20% of 1RM combined with IBFR (LL + IBFR), or low-load exercises at 20% of 1RM without BFR (LL). Twelve RT sessions were performed for 6 weeks, twice a week. A comparative analysis of the activation of the biceps and triceps brachial muscles after the bench press, triceps pulley, and biceps pulley exercises did not reveal group × evaluations × sets, group × evaluations, group × sets, or evaluations × sets interactions with regard to group, evaluation, or sets (p > 0.05). However, the evaluations showed a significant increase in the LI+IBFR group after the 1st, 2nd, and 4th sets (p < 0.05) only with regard to biceps muscle activation. It was concluded that the muscle activations of the biceps and triceps are similar with regard to the bench press, triceps pulley, and biceps pulley exercises when CBFR is compared with IBFR; however, IBFR improved the muscle activation of the biceps brachial only with regard to the front pull down exercise.se....(AU)

O treinamento de força (TF) com restrição de fluxo sanguíneo (RFS) tem sido utilizado para o aumento da força e hipertrofia muscular, entretanto, ainda não foi estabelecido a melhor estratégia para realizar a RFS (contínua ou intermitente). O objetivo do estudo foi analisar o efeito crônico do TF com a RFS, contínua ou intermitente, sobre ativação muscular. Participaram do estudo 24 homens com experiência em TF que foram divididos aleatoriamente em três grupos experimentais: a) exercícios de baixa carga a 20% de 1RM combinado com a RFS contínua (BC + RFSC), b) exercícios de baixa carga a 20% de 1RM combinado com a RFS intermitente (BC + RFSI), c) exercícios de baixa carga a 20% de 1RM sem a RFS (BC). Foram realizadas 12 sessões de TF (duração de seis semanas, sendo duas vezes por semana). Na primeira e na última sessão foi avaliada a ativação muscular do bíceps e tríceps nos quatro exercícios (supino reto, puxada frontal, rosca tríceps e rosca bíceps, respectivamente). Na análise comparativa da ativação muscular do bíceps e do tríceps braquial nos exercícios: supino reto, rosca tríceps e rosca bíceps, observou-se que não existiram interações entre grupo × avaliações × séries, grupo × avaliações, grupo × séries, avaliações × séries, no grupo, nas avaliações e nas séries (p > 0,05); entretanto, nas avaliações houve aumento significativo no grupo BC+RFSI, na 1ª, 2ª e 4ª séries (p < 0,05) apenas na ativação muscular do bíceps. Conclui-se que a ativação muscular do bíceps e tríceps parecem ser semelhantes nos exercícios supino reto, rosca tríceps e rosca bíceps quando comparada a RFS contínua vs. intermitente, porém, a RFS intermitente parece melhorar a ativação muscular do bíceps braquial apenas no exercício puxada frontal....(AU)

The Effect of Ballistic Exercise as Pre-Activation for 100 m Sprints.

The benefits of warm-up in sports performance has received a special interest in the current literature. However, there is a large gap of knowledge about the tasks to be performed, specifically in the real competitive environment. The purpose of the study was to verify the acute effects of a warm-up including ballistic exercises in 100 m running performance. In addition, a second 100 m trial was assessed to better understand the warm-up effects in training and competition. Eleven men (25.4 ± 6.2 years of age, 1.76 ± 0.08 m of height, 78.2 ± 8.6 kg of body mass) were submitted to three different protocols, in a randomized order: no warm-up (NWU), typical warm-up (WU) and WU complemented with ballistic exercises (PAP). Biomechanical, physiological and psychophysiological variables were assessed. Differences were found between the three conditions assessed in the first 100 m sprint with 7.4% and 7.6% faster performances after the WU and PAP, compared to NWU. Stride length was higher in the second part of the 100 m after PAP compared with WU. These results highlight the positive effects of warm-up for sprinting performance. The inclusion of ballistic exercises, besides being used to improve sprint performance, can increase stride length in the final of the 100 m race.

Are there differences in auscultatory pulse in total blood flow restriction between positions, limbs and body segments? / Existem diferenças no pulso auscultatório da restrição total de fluxo sanguíneo entre as posições, membros e segmentos corporais?

Verification of the auscultatory pulse in total blood flow restriction (BFR) has been a limiting factor in studies due to the way in which it is evaluated and prescribed, as hemodynamic measurements can be directly affected by gravity. The aim of the present study was to compare the auscultatory pulse in BFR between positions, genders, limbs and body segments in healthy young individuals. A total of 156 subjects participated in the study, 76 of whom were male and 80 of whom were female (23.9±3.7 years, 66.5±11.5 kg, 1.67±0.07 m). After filling in registration data, anthropometry was evaluated, and BFR pressure was determined. BFR was evaluated in a randomized manner in both limbs (upper and lower) and in both segments (right and left) in the following positions: a) lying in the supine position; B) sitting with knees and trunk at 90°; and c) standing in the anatomical position. Significant differences were observed between the lying, sitting and standing positions (p<0.05), between genders (p<0.05), between limbs (p<0.05) and between the right and left segments in the lower limb in both genders [males (p=0.014) and females (p=0.009)] in the lying position. However, no significant differences were observed between the right and left segments in the upper limbs (p>0.05). The BFR point appears to differ between positions, genders, lower limbs and segments. Therefore, it is recommended that health professionals should check the BFR point in the position relating to the exercise that will be performed, taking into account gender, lower limbs and body segments.

A verificação do pulso auscultatório da restrição de fluxo sanguíneo (RFS) total tem sido fator limitante dos estudos devido à forma de avaliação e prescrição, já que as medidas hemodinâmicas podem sofrer influência direta da gravidade. O objetivo do presente estudo foi comparar o pulso auscultatório da RFS entre as posições, sexo, membros e segmentos corporais em jovens saudáveis. Participaram do estudo 156 sujeitos, sendo 76 homens e 80 mulheres (23,9±3,7 anos, 66,5±11,5 kg, 1,67±0,07 m). Após o preenchimento da ficha cadastral, foram avaliadas a antropometria e em seguida houve a determinação da pressão de RFS. A RFS foi avaliada de forma randomizada em ambos os membros (superiores e inferiores) e ambos os segmentos (direito e esquerdo) nas posições: a) deitada em decúbito dorsal; b) sentada com joelhos e tronco em 90°; e c) em pé na posição anatômica. Observaram-se diferenças significativas entre as posições deitado, sentado e em pé (p<0,05), entre os sexos (p<0,05), entre os membros (p<0,05) e entre os segmentos direito vs. esquerdo no membro inferior em ambos os sexos [homem (p=0,014) e mulher (p=0,009)] na posição deitada. Entretanto, observou-se não existir diferenças significativas entre os segmentos direito vs. esquerdo no membro superior (p>0,05). O ponto da RFS parece diferir entre as posições, sexo, membros inferiores e segmentos. Portanto, recomenda-se que os profissionais da área da saúde devam verificar o ponto da RFS na posição referente ao exercício que será realizado, levando em consideração o sexo, membros inferiores e segmentos corporais.

Mood Effects of Blood Flow Restriction Resistance Exercise Among Basketball Players.

This study compared the acute effects of resistance exercise with and without blood flow restriction (BFR) on basketball players' mood states. A total of 11 male basketball players (M age = 19.9, SD = 2.8 years; M height = 180.8, SD = 7.8 cm; M weight = 71.1, SD = 9.1 kg; M body mass index = 22.1, SD = 1.9 kg/m2) were randomly assigned to two experimental conditions: (a) low-load resistance exercise with BFR (LLRE + BFR) and high-load resistance exercise (HLRE) without BFR. We measured mood state with the Brunel Mood Scale before and after each session. There was a significant interaction effect such that there was increased fatigue over time with LLRE + BFR ( p = .001, Δ% = 169.2). Regarding total mood disorder, there were significant pre and postexercise differences between athletes exposed to both the LLRE + BFR and HLRE conditions ( p = .048) and a decharacterization of the iceberg mood profile in the post-training LLRE + BFR condition. LLRE + BFR, compared to HLRE, promoted an acute negative effect on mood state, decharacterization of the iceberg profile, total mood disturbance, and increased participant fatigue, suggesting that this method of strength training should be avoided before sports competitions.

Does a resistance exercise session with continuous or intermittent blood flow restriction promote muscle damage and increase oxidative stress?

The aim of this study was to compare the effect of low-load resistance exercise (LLRE) with continuous and intermittent blood flow restriction (BFR) on the creatine kinase (CK), lactate dehydrogenase (LDH), protein carbonyl (PC), thiobarbituric acid-reactive substance (TBARS) and uric acid (UA) levels in military men. The study included 10 recreationally trained men aged 19 ± 0.82 years who underwent the following experimental protocols in random order on separate days (72-96 h): 4 LLRE sessions at a 20% 1RM (one-repetition maximum [1RM]) with continuous BFR (LLRE + CBFR); 4 LLRE sessions at 20% 1RM with intermittent BFR (LLRE + IBFR) and 4 high-intensity resistance exercise (HIRE) sessions at 80% 1RM. The CK and LDH (markers of muscle damage) levels were measured before exercise (BE), 24 h post-exercise and 48 h post-exercise, and the PC, TBARS and UA (markers of oxidative stress) levels were measured BE and immediately after each exercise session. There was a significant increase in CK in the HIRE 24 post-exercise samples compared with the LLRE + CBFR and LLRE + IBFR (P = 0.035, P = 0.036, respectively), as well as between HIRE 48 post-exercise and LLRE + CBFR (P = 0.049). Additionally, there was a significant increase in CK in the LLRE + CBFR samples BE and immediately after each exercise (Δ = 21.9%) and in the HIRE samples BE and immediately after each exercise, BE and 24 post-exercise, and BE and 48 post-exercise (Δ values of 35%, 177.6%, and 177.6%, respectively). However, there were no significant changes in LDH, PC, TBARS, and UA between the protocols (P > 0.05). Therefore, a physical exercise session with continuous or intermittent BFR did not promote muscle damage; moreover, neither protocol seemed to affect the oxidative stress markers.

Acute Effects of Resistance Exercise With Continuous and Intermittent Blood Flow Restriction on Hemodynamic Measurements and Perceived Exertion.

This study compared the acute effects of low-intensity resistance exercise (RE) sessions for the upper limb with continuous and intermittent blood flow restriction (BFR) and high-intensity RE with no BFR on lactate, heart rate, double product (DP; heart rate times systolic blood pressure), and perceived exertion (RPE). Ten recreationally trained men (1-5 years strength training; age mean = 19 ± 0.82 years) performed three experimental protocols in random order: (a) low-intensity RE at 20% one-repetition maximum (1RM) with intermittent BFR (LI + IBFR), (b) low-intensity RE at 20% 1RM with continuous BFR (LI + CBFR), and (c) high-intensity RE at 80% 1RM. The three RE protocols increased lactate and DP at the end of the session ( p < .05) and increased heart rate at the end of each exercise ( p < .05). However, greater local and general RPE was observed in the high-intensity protocol compared with LI + IBFR and LI + CBFR in the lat pull-down, triceps curl, and biceps curl exercises ( p < .05). A greater percentage change in DP and lactate was observed for continuous BFR compared with intermittent BFR; however, RPE was lower for intermittent BFR. In conclusion, intermittent BFR appears to be an excellent option for physical training because it did not differ significantly from continuous BFR in any variable and promoted a lower percentage change in DP and RPE.

Effects of resistance training with blood flow restriction on haemodynamics: a systematic review.

This study systematically reviewed the available scientific evidence on the changes promoted by low-intensity (LI) resistance training (RT) combined with blood flow restriction (BFR) on blood pressure (BP), heart rate (HR) and rate-pressure product (RPP). Searches were performed in databases (PubMed, Web of Science™ , Scopus and Google Scholar), for the period from January 1990 to May 2015. The study analysis was conducted through a critical review of contents. Of the 1 112 articles identified, 1 091 were excluded and 21 met the selection criteria, including 16 articles evaluating BP, 19 articles evaluating HR and four articles evaluating RPP. Divergent results were found when comparing the LI protocols with BFR versus LI versus high intensity (HI) on BP, HR and RPP. The evidence shows that the protocols using continuous BFR following a LIRT session apparently raise HR, BP and RPP compared with LI protocols without BFR, although increases significantly in BP seem to exist between the HI protocols when compared to LI protocols. Haemodynamic changes (HR, SBP, DBP, MBP, RPP) promoted by LIRT with BFR do not seem to differ between ages and body segments (upper or lower), although they are apparently affected by the width of the cuff and are higher with continuous BFR. However, these changes are within the normal range, rendering this method safe and feasible for special populations.