Effect of Photobiomodulation Therapy in the 1500 m Run: An Analysis of Performance and Individual Responsiveness.

Objective: The aims of this study were to verify the effects of photobiomodulation therapy (PBMT) on time trial run performance over 1500 m, as well as on individual responsiveness of recreative runners. Materials and methods: Nineteen recreationally trained runners participated in a randomized, crossover, double-blind placebo-controlled trial. The study was divided in four sessions: (1) incremental maximal running test; (2) 1500 m run control (without placebo or PBMT); and (3, 4) PBMT or placebo before 1500 m run. PBMT or placebo was applied over 14 sites per lower limb immediately before time trial run using a mixed wavelength device (33 diodes: 5 LASERs of 850 nm, 12 LEDs of 670 nm, 8 LEDs of 880 nm, and 8 LEDs with 950 nm). PBMT delivered 30 J per site, with a total energy dose of 840 J. Physiological variables [maximal oxygen uptake (VO2MAX), velocity associated to VO2MAX (vVO2MAX), peak of velocity, and respiratory compensation point (RCP)] were assessed during incremental maximal test. During 1500 m races we accessed the following: time, heart rate, and lower limb rate perception exertion per lap, total time, and blood lactate concentration ([Lac]). Results: PBMT had no significant difference and likely trivial effect for performance in the total time trial run over 1500 m compared to placebo. In the responsiveness analyses, 10 participants positively responded to PBMT, whereas total time reduced for responders (-10.6 sec; -3.18%) and increased for nonresponders (+6.0 sec; +1.73%). Responders presented higher aerobic parameters (VO2MAX and RCP) than nonresponders. Moreover, responders had lower time per lap and [Lac] (1 and 3 min) when PBMT was applied. Conclusions: PBMT applied immediately before running in noncontrolled environment was not able to improve the 1500 m performance of recreationally trained runners. However, responders to PBMT presented higher aerobic capacity than nonresponders.

Dose-Response Effect of Photobiomodulation Therapy on Muscle Performance and Fatigue During a Multiple-Set Knee Extension Exercise: A Randomized, Crossover, Double-Blind Placebo-Controlled Trial.

Objective: The aim of this study was to identify the best energy dose of photobiomodulation therapy (PBMT) able to improve muscle performance and reduce fatigue during multiple-set knee extension exercise. Methods: Eighteen physically active men participated in this study. Each participant performed an isokinetic exercise protocol (5 sets of 10 knee extension repetitions, maximum contractions at 60°·s-1) in 6 sessions, 1 week apart. Control condition (no PBMT/placebo treatments) was applied at the first and sixth sessions. Placebo or PBMT with 135, 270, or 540 J/quadriceps was randomly applied from the second to fifth sessions. Placebo/PBMT treatments were always applied at two moments: 6 h before and immediately before exercise. The isometric and isokinetic concentric peak torques were assessed before and after the exercise protocol. Results: The knee extension exercise performance (total work performed during exercise) was not affected by PBMT (135, 270, and 540 J) compared with placebo treatment. However, all PBMT treatments (135, 270, and 540 J) led to lower percentage drop compared with placebo and control conditions on isometric peak torque (IPT), concentric peak torque (CPT), and concentric work (W). All PBMT doses led to possibly positive or likely positive effects on IPT, CPT, and W compared with placebo. Conclusions: Our findings demonstrate that PBMT with 135, 270, and 540 J applied at two moments (6 h before and immediately before exercise) was able to produce the same total work with lower fatigue, which may facilitate the performance of additional sets (i.e., higher training volume).

Recovery following Rugby Union matches: effects of cold water immersion on markers of fatigue and damage.

We investigated the effect of postmatch cold-water immersion (CWI) on markers of muscle damage, neuromuscular fatigue, and perceptual responses within 72 h after a rugby match. Twenty-two professional male rugby players were randomized into CWI (10 °C/10 min; n = 11) or control (CON: 30 min seated; n = 11) groups. Activity profile from Global Positioning Satellite systems and postmatch rating of perceived exertion were measured to determined match load. Biochemical (tumor necrosis factor alpha (TNF-α), interleukin-6), neuromuscular performance (squat (SJ) and countermovement jumps (CMJ), peak power output (PPO), rate of force development (RFD), stiffness, 10- and 30-m sprint time, and perceptual markers (soreness, perceived recovery) were obtained before and immediately after the match, and then at 30 min, 24 h, 48 h, and 72 h after the match. Magnitude-based inference and Cohen's effect size (ES) were used to analyze change over time and between groups. Thus, the higher/beneficial, similar/trivial, or lower/harmful differences were evaluated as follows: <1%, almost certainly not; 1% to 5%, very unlikely; 5% to 25%, unlikely; 25% to 75%, possible; 75% to 95%, likely; 95% to 99%, very likely; >99%, almost certainly. Changes were unclear for the match loads, sprint times, and perceptual markers between groups. Higher %ΔSJ at 24 h (very likely (ES = 0.75)) and in %ΔPPO_SJ at 48 h (likely (ES = 0.51)) were observed in CWI than in CON. Values in %ΔRDF_CMJ were higher immediately after (likely (ES = 0.83)), 30 min after (very likely (ES = 0.97)), and 24 h after the match (likely (ES = 0.93)) in CWI than in CON. Furthermore, %Δlog TNF-α were lower in the CWI group than in the CON group immediately after (almost certainly (ES = -0.76)), 24 h after (very likely (ES = -1.09)), and 72 h after the match (likely (ES = -0.51)), and in Δstiffness_SJ at 30 min after (likely (ES = -0.67)) and 48 h after the match (very likely (ES = -0.97)). Also, different within-groups effects throughout postmatch were reported. Implementing postmatch CWI-based strategies improved the recovery of markers of inflammation and fatigue in rugby players, despite no change in markers of speed or perceptual recovery.

Dose-response effect of photobiomodulation therapy on neuromuscular economy during submaximal running.

The purpose of this study was to verify the photobiomodulation therapy (PBMT) effects with different doses on neuromuscular economy during submaximal running tests. Eighteen male recreational runners participate in a randomized, double-blind, and placebo-controlled trial, which each participant was submitted to the same testing protocol in five conditions: control, placebo, and PBMT with doses of 15, 30, and 60 J per site (14 sites in each lower limb). The submaximal running was performed at 8 and 9 km h-1 during 5 min for each velocity. Muscle activation of the vastus lateralis (VL), vastus medialis (VM), rectus femoris (RF), biceps femoris (BF), and gastrocnemius lateralis (GL) was collected during the last minute of each running test. The root mean square (RMS) was normalized by maximal isometric voluntary contraction (MIVC) performed a priori in an isokinetic dynamometer. The RMS sum of all muscles (RMSLEG) was considered as main neuromuscular economy parameter. PBMT with doses of 15, 30, and 60 J per site [33 diodes = 5 lasers (850 nm), 12 LEDs (670 nm), 8 LEDs (880 nm), and 8 LEDs (950 nm)] or placebo applications occurred before running tests. For the statistical analysis, the effect size was calculated. Moreover, a qualitative inference was used to determine the magnitude of differences between groups. Peak torque and RMS during MIVCs showed small effect sizes. According to magnitude-based inference, PBMT with dose of 15 J per site showed possibly and likely beneficial effects on neuromuscular economy during running at 8 and 9 km h-1, respectively. On other hand, PBMT with doses of 30 and 60 J per site showed possible beneficial effects only during running at 9 km h-1. We concluded that PBMT improve neuromuscular economy and the best PBMT dose was 15 J per site (total dose of 420 J).

Is respiratory exchange ratio an alternative to estimate anaerobic threshold in trained runners? / A razão de troca respiratória é uma alternativa para estimar o limiar anaeróbio em corredores treinados?

Abstract Several studies showed that respiratory exchange ratio (RER) have been used as an alternative to evaluate the aerobic capacity in a single incremental test. However, few studies have investigated trained runners. The aim of this study was to verify if the respiratory exchange ratio (RER) could be used as an alternative criterion for estimating anaerobic threshold (AT) in long-distance runners. Nineteen male long-distance runners volunteered to participate in the study. An incremental treadmill test was performed with initial speed of 10 km∙h-1 with increments of 1 km∙h-1 every 1 min until voluntary exhaustion. The variables measured were oxygen uptake (VO2), first and second ventilatory thresholds (VT1 and VT2, respectively), intensity corresponding to RER level of 1.0 (iRER1.0), peak velocity (PV), heart rate (HR), and rate of perceived exertion (RPE). One-way repeated measure analysis variance was used, following Bonferroni post hoc test. Agreement between parameters was evaluated by Pearson correlation and dispersion error. There were no significant differences between iRER1.0 and VT2 parameters. The correlations were significant between iRER1.0 and VT2 parameters for absolute and relative VO2, speed, and HR (r=0.95; r=0.60; r=0.72; r=0.81, respectively). A small mean error (-0.2 km∙h-1) was observed between iRER1.0 and VT2. However, it was also observed an overestimation trend for high speeds. In conclusion, iRER1.0 can be used as an alternative method to detect AT in long distance runners. However, its use is limited in runners with high aerobic capacity.

Resumo Diversos estudos demonstram que a razão de troca respiratória (RER) tem sido utilizada como uma alternativa para estimar a capacidade aeróbia em único teste incremental. No entanto, poucos estudos foram realizados com corredores treinados. Sendo assim, o objetivo do estudo foi avaliar a utilização do RER como uma alternativa para estimar o limiar anaeróbio (AT) em corredores de longa distância. Dezenove corredores de longa distância do sexo masculino participaram do estudo. Foi realizado um teste incremental com velocidade inicial de 10 km∙h-1 com incrementos de 1 km∙h-1 a cada minuto até a exaustão voluntária. As variáveis mensuradas foram consumo de oxigênio (VO2), limiares ventilatórios (VT1 e VT2), intensidade correspondente ao RER no valor igual a 1,0 (iRER1.0), pico de velocidade (PV), frequência cardíaca (HR) e percepção subjetiva de esforço (RPE). Foi realizada a análise de variância de medidas repetidas do tipo one-way, seguido do teste post hoc de Bonferroni. A relação entre as variáveis foi verificada pela correlação de Pearson e a concordância por meio da medida de dispersão dos erros. Não houve diferença significativa entre as variáveis iRER1.0 e VT2. Foram encontradas correlações significativas entre as variáveis iRER1.0 e VT2 para os valores absolutos e relativos de VO2, velocidade e HR (r=0,95; r=0,60; r=0,72; r=0,81, respectivamente). Um pequeno erro médio (-0,2 km∙h-1) foi observado entre iRER1.0 e VT2, bem como uma tendência de superestimação em altas velocidade. Em conclusão, iRER1.0 pode ser utilizado como um método alternativo para detectar o AT em corredores de longa distância, entretanto, seu uso é limitado em corredores com alta capacidade aeróbia.

Effects of mate tea consumption on muscle strength and oxidative stress markers after eccentric exercise.

Dietary phytochemical supplementation may improve muscle recovery from exercise. In this study, we investigated the effect of mate tea (MT) consumption - a phenol-rich beverage - on muscle strength and oxidative stress biomarkers after eccentric exercise. In a randomised, cross-over design, twelve men were assigned to drink either MT or water (control; CON) for 11 d. On the 8th day, subjects performed three sets of twenty maximal eccentric elbow flexion exercises. Maximal isometric elbow flexion force was measured before and at 0, 24, 48 and 72 h after exercise. Blood samples were obtained before and at 24, 48 and 72 h after exercise and analysed for total phenolics, GSH, GSSG, GSH:GSSG ratio and lipid hydroperoxides (LOOH). After eccentric exercise, muscle strength was significantly reduced over time, regardless of treatments. However, MT improved the rate of strength recovery by 8·6 % on the 1st day after exercise (P<0·05). Plasma concentration of total phenolic compounds was higher in MT than in CON at all time points (P<0·05) but decreased significantly at 72 h after exercise in both trials (P<0·05). Blood levels of GSH were significantly decreased at 48 and 72 h after exercise in CON (P<0·05) but did not change over time in MT. No significant changes were observed for GSSG, GSH:GSSG ratio and LOOH levels. MT intake did not influence muscle strength at all time points assessed but hastened the strength recovery over 24 h after exercise. MT also favoured the concentration of blood antioxidant compounds.

Utilização da distância total percorrida no teste específico de hoff como preditor da velocidade de limiar anaeróbio no futebol / Use of maximal running distance performed on hoff test for anaerobic threshold prediction in soccer

OBJETIVO: Verificar a utilização da distância total percorrida no teste de Hoff como preditor da intensidade de limiar anaeróbio em jovens futebolistas. MÉTODOS: Para isso, 10 jovens jogadores de futebol (idade de 17 ± 1 ano e massa corporal de 64,3 ± 2,1 kg) participaram do estudo. Os sujeitos foram submetidos aos testes de 12 minutos, lactato mínimo para estimar a velocidade de limiar anaeróbio (vLAn) e ao teste de Hoff específico para o de futebol. O objetivo no teste de Hoff foi percorrer a máxima distância possível em 10 minutos de exercício conduzindo a bola de futebol em um circuito composto por dribles, saltos e corridas em direções diversas. RESULTADOS: A distância total percorrida no teste de 12 minutos foi 2.673,2 ± 64,7 m, a vLAn 11,6 ± 0,3 km.h-1 e a distância percorrida no Hoff 1.458,7 ± 49,6 m. A distância total percorrida no teste de Hoff não foi significativamente correlacionada com a vLAn (r = -0,20; P < 0,05) e com a distância percorrida no teste de 12 minutos (r = -0,15; P < 0,05). No entanto, a vLAn e a velocidade correspondente a 90% da velocidade média no teste de 12 minutos (12,0 ± 0,3 km.h-1) não foram diferentes significativamente e foram significativamente correlacionadas (r = 0,65; P < 0,05). CONCLUSÃO: Assim, pode-se concluir que a distância total percorrida no teste de Hoff não pode ser utilizada para predição da velocidade de limiar anaeróbia em futebolistas.

OBJECTIVE: To verify the use of maximal running distance performed on Hoff test to predict the anaerobic threshold speed (sAnT). METHODS: Ten young soccer players (age of 17 ± 1 years and body mass of 64.3 ± 2.1 kg) were subjects of the study. The subjects performed 12-min test, lactate minimum test to estimate the anaerobic threshold speed and a field test called Hoff. The purpose of Hoff test was to cover the maximum distance during a period of 10min moving a soccer ball through the track by dribbling. RESULTS: The distance covered during 12-min was 2673.2 ± 64.7 m, the sAnT was 11.6 ± 0.3 km.h-1 and distance covered during test Hoff test was 1458.7 ± 49.6 m. The distance covered during Hoff test was not significantly correlated with sAnT (r = -0.20; P > 0.05) and distance covered during 12-min test (r = -0.15; P > 0.05). The sAnT did not differ of speed correspondent 90% at 12-min speed and they were statistically correlated (r = 0.65). CONCLUSION: Thus, we concluded that maximal distance covered during Hoff test cannot provides a valid prediction of the anaerobic threshold speed.