Effect of different time intervals of light emitting diode therapy application on muscle fatigue

Este estudio tuvo como objetivo identificar el momento idóneo de aplicación del diodo emisor de luz (LED) del infrarrojo cercano (NIR) en la potencia máxima isocinética de los flexores del codo. Este fue un estudio cruzado prospectivo, aleatorizado, simple-ciego, con pre–test y post-test, y controlado con placebo. Se asignaron al azar cuarenta y cinco no deportistas sanos a 3 grupos por igual: grupos de 5 minutos, 1 hora y 5 horas. Cada grupo (n = 15) tuvo en la primera sesión NIR-LED de 890 nm de longitud de onda, en condiciones activas o placebo, antes del ejercicio que provoca fatiga (5 minutos, 1 hora o 5 horas). Después de un intervalo de 7 días, se aplicó la segunda condición NIR-LED en la segunda sesión. La evaluación de la potencia máxima isocinética se realizó antes y después del ejercicio en cada sesión utilizando un dinamómetro isocinético. No hubo diferencias significativas entre los grupos y entre las condiciones en la potencia máxima isocinética (p > 0.05). La potencia máxima isocinética disminuyó significativamente después del tratamiento en comparación con el pretratamiento (p < 0.01) en todos los grupos, pero el grupo de 5 minutos mostró el menor porcentaje de disminución. En conclusión, lo más probable es que NIR-LED pueda resistir la fatiga muscular con los parámetros utilizados en este estudio si se emplea 5 minutos antes del ejercicio. This study aimed to identify the near-infrared (NIR) light emitting diode (LED) time response on isokinetic peak torque of elbow flexors. This was a prospective, randomized, single blind, pre–test post-test, and placebo-controlled crossover study. Forty-five healthy non-athletes were assigned at random to 3 groups equally: 5 minutes, 1-hour and 5-hours groups. Each group (n=15) had at the first session 890 nm wavelength NIR-LED, either in active or placebo conditions, prior to exercise that provokes fatigue (5 minutes, 1 hour, or 5 hours). After an interval of 7 days, the second NIR-LED condition was applied at the second session. The assessment of isokinetic peak torque was done at base line and post exercise in each session using isokinetic dynamometer. There was no significant difference between groups and between conditions in isokinetic peak torque (p > 0.05). Isokinetic peak torque decreased significantly post treatment compared with pretreatment (p < 0.01) in all groups, but the 5 minutes group showed the least percent of decrease. In conclusion, NIR-LED can most probably resist muscle fatigue with the parameters used in this study if it is employed 5 minutes before exercise.

Immediate and 6-week effects of wearing a knee sleeve following anterior cruciate ligament reconstruction: a cross-over laboratory and randomised clinical trial

Background Rehabilitation following anterior cruciate ligament (ACL) reconstructions is based mainly on comprehensive progressive exercise programmes using a multi-dimensional approach. Elastic knee sleeves may be useful adjuncts to rehabilitation. The aim of this study was to determine the immediate and 6-week effects of wearing a knee sleeve on person-reported outcomes and function in participants who had undergone an ACL reconstruction and who had residual self-reported functional limitations. Methods Individuals with ACL reconstruction in the previous 6 months to 5 years were recruited. Immediate effects of a commercially-available elastic knee sleeve on single-leg horizontal hop distance were explored using a cross-over design. Following this first session, participants were randomised into a Control Group and a Sleeve Group who wore the sleeve for 6 weeks, at least 1 h daily. Outcome measures for the randomised clinical trial (RCT) were the International Knee Documentation Classification Subjective Knee Form (IKDC-SKF) score, the single-leg horizontal hop distance, and isokinetic quadriceps and hamstring peak torque. Linear mixed models were used to determine random effects. Where both limbs were measured at multiple time points, a random measurement occasion effect nested within participant was used. Results Thirty-four individuals (16 women) with ACL reconstruction completed the cross-over trial. Hop distance for the injured side during the sleeve condition increased by 3.6 % (95 % CI 0.4–6.8 %, p = 0.025). There was no evidence of differential changes between groups for the IKDC-SKF (Sleeve Group n = 15; Control Group n = 16; p = 0.327), or relative improvement in the injured side compared to the uninjured side for the physical performance measures (Sleeve Group n = 12, Control Group n = 12; three-way interaction p = 0.533 [hop distance], 0.381 [quadriceps isokinetic peak torque], and 0.592 [hamstring isokinetic peak torque]). Conclusions Single-leg hop distance of the ACL reconstructed side improved when wearing a knee sleeve. Wearing the knee sleeve over 6 weeks did not lead to enhanced improvements in self-reported knee function, hop distance and thigh muscle strength compared to the control group. Trial registration The trial was prospectively registered with the Australia New Zealand Clinical Trials Registry No: ACTRN12618001083280, 28 June 2018.

Strength development according with age and position: a 10-year study of 570 soccer players

Background/aimThe purpose of this study was to compare the isokinetic peak torque profiles from the quadriceps and hamstrings muscles during concentric and eccentric contractions in elite Brazilian soccer players across different field positions and age categories. Our hypothesis was that soccer players from different field positions are subjected to different ageing-related effects on their isokinetic peak torque.MethodsThis is a retrospective study based on professional elite-level soccer players between the years 2009 and 2019. It included 570 adult males who played for at least 5 years on first or second Brazilian divisions. Playing positions were divided as: goalkeepers, defenders, sidebacks, midfielders and forwards. Age categories were also divided as: G1 (17–20 years old), G2 (21–24 years old), G3 (25–28 years old), G4 (29–32 years old) and G5 (33 years old or more).ResultsThe results indicate a moderate effect of age (F(4545)=8.197; p<0.001; η2=0.057) and a small effect of playing position (F(4545)=2.993; p<0.05; η2=0.021) on torque of concentric extensors; mainly from midfielders and goalkeepers with 29 years or more.ConclusionsSoccer players from different field positions are subjected to different ageing related effects on their muscular performance during their career special attention should be given to these players to avoid reduction in physical performance.

Ipsilateral and Contralateral Torque Responses to Bilateral and Unilateral Maximal, Fatiguing, Isokinetic Leg Extensions

Background: Few studies have compared performance fatigability (PF) for bilateral versus unilateral isokinetic tasks. Objectives: The purpose of this study was to examine: Mode-specific testing responses to isokinetic fatigue, differences in PF between bilateral and unilateral leg extensions, and the effects of fatiguing, unilateral, dynamic leg extensions on contralateral isokinetic peak torque (PT) and maximal voluntary isometric contraction (MVIC). Methods: Eight men (mean ± SD: age= 22.5 ± 2.5 yr.) completed pre- and post-testing for PT and MVIC following 50 bilateral, unilateral right or left leg maximal, isokinetic leg extensions at 180°·s-1, on three separate days. Fatigue-induced decreases in PT and MVIC were used to quantify PF. The data were analyzed with a 4-way repeated measures ANOVA, follow up, and post-hoc analyses. Results: The results indicated that there were no differences (p > 0.05) in PF for the bilateral versus unilateral fatiguing tasks, decreases in PT (p < 0.001 - 0.016; d = 0.54 - 2.58) and MVIC (p < 0.001 - 0.006; η2p = 0.682 - 0.962) for the exercised legs during unilateral fatigue, and a contralateral increase (p = 0.007) in PT following the right leg fatiguing task. Conclusion: The results indicated that PT was more sensitive to fatiguing isokinetic tasks than was MVIC. In addition, there was a facilitation of PT in the contralateral leg following unilateral right leg fatigue. The differences in PT and MVIC testing may be attributable to the timing and/or relative contributions of peripheral and central fatigue.

The Effect of Dietary Nitrate Supplementation on Isokinetic Torque in Adults: A Systematic Review and Meta-Analysis

Dietary nitrate (NO3−) supplementation, which can enhance performance in exercise settings involving repeated high-intensity efforts, has been linked to improved skeletal muscle contractile function. Although muscular strength is an important component of explosive movements and sport-specific skills, few studies have quantified indices of muscular strength following NO3− supplementation, particularly isokinetic assessments at different angular velocities. We performed a systematic review and meta-analysis to determine whether dietary NO3− supplementation improves peak torque, as assessed by the gold standard method of isokinetic dynamometry, and if this effect was linked to the angular velocity imposed during the assessment. Dialnet, Directory of Open Access Journals, MEDLINE, PubMed, SciELO, Scopus, and SPORTDiscus were searched for articles using the following search strategy: (nitrate OR beet*) AND (supplement* OR nutr* OR diet*) AND (isokinetic OR strength OR “resistance exercise” OR “resistance training” OR “muscular power”). The meta-analysis of data from 5 studies with 60 participants revealed an overall effect size of −0.01 for the effect of nitrate supplementation on isokinetic peak torque, whereas trivial effect sizes ranging from −0.11 to 0.16 were observed for independent velocity-specific (90°/s, 180°/s, 270°/s, and 360°/s) isokinetic peak torque. Four of the five studies indicated that dietary NO3− supplementation is not likely to influence voluntary knee extensor isokinetic torque across a variety of angular velocities. These results suggest that NO3− supplementation does not influence isokinetic peak torque, but further work is required to elucidate the potential of NO3− supplementation to influence other indices of muscular strength, given the dearth of experimental evidence on this topic.

Correlation between bone mineral density, isokinetic peak torque and postural balance in postmenopausal women

Background: Postmenopausal women typically present loss of bone mineral density (BMD), muscular strength, and postural balance. However, there is no consensus in the literature on the correlation between these variables. Objectives: Our objective was to verify the correlation between BMD, isokinetic peak torque of knee extensors and flexors, and static postural balance in postmenopausal women. Methods: Fifty-one postmenopausal women underwent BMD evaluation through dual-energy X-ray absorptiometry (DXA) for four bone regions (lumbar spine, femoral neck, total hip, and trochanter). Muscular strength of knee extensors and flexors was evaluated in an isokinetic dynamometer at 60 and 180 degrees per second in the dominant lower limb. Static postural balance was evaluated on a force platform during five different tasks (bipodal eyes open, bipodal eyes closed, semi-tandem eyes open, semi-tandem eyes closed, and unipodal). Statistical analysis involved Spearman’s correlation coefficient (rho). Results: There was no significant correlation between BMD and isokinetic peak torque of knee extensors and flexors. Approximately half (27 of 60) of the postural balance variables presented significant inverse correlations (p < 0.05) with BMD and of these, the majority (22 of 27) presented moderate correlation (rho between -0.49 and -0.30). Most correlations were for bipodal support tasks with eyes open and eyes closed. Conclusion: Greater postural oscillation in different balance tasks was correlated with lower BMD in postmenopausal women. Therefore, it is suggested that intervention protocols for women with impaired BMD, especially osteoporotic, consider balance training as part of rehabilitation.

Physical, physiological and psychological profiles of elite Turkish taekwondo athletes

SummaryStudy aim: To identify the physical, physiological and psychological profiles of elite Turkish taekwondo athletes.Material and methods: Twelve players of the Turkish national taekwondo team (age = 22.7 ± 2.8 years, BMI = 22.2 ± 1.4 kg/m2, body fat = 12.8 ± 3.4%) participated in the study. Anthropometric measurements including leg length and foot size were assessed. Maximal oxygen uptake, explosive power of leg extensors, isokinetic peak torque, muscular endurance, anaerobic power, agility, flexibility, maximal speed, reaction time, and postural balance were examined by incremental treadmill running, vertical jump, isokinetic strength, sit-ups and push-ups, Wingate, shuttle run, sit-and-reach, 30-meter sprint, multiple-choice reaction time, and General Postural Stability and Athlete Single Leg stability tests, respectively. Psychological characteristics including mental skills and mood states were evaluated using OMSAT-3 and POMS tests.Results: VO2max, isokinetic peak torque and Wingate test mean power values were 54.1 ± 4.4 mL ∙ kg−1 ∙ min−1, 191.7 ± 19.2 N ∙ m, and 9 ± 0.7 W/kg, respectively. Postural stability index 0.18 ± 0.06, single leg stability index 0.82 ± 0.11, reaction time 0.344 ± 0.032 s, 10 × 5-m shuttle run 17.09 ± 0.68 s, 30-meter sprint 4.60 ± 0.23 s, and vertical jump 43.5 ± 6.1 cm were the other values reported. The highest scores for the 12 mental skills in OMSAT-3 were for goal setting (6.25 ± 0.45) and self-confidence (6.16 ± 0.45). The lowest score was for Imagery (5.64 ± 0.36). The results of six mood states of POMS showed higher scores on the Vigor-activity, Anger-Hostility and Tension-Anxiety scales and lower scores on Depression-Dejection, Fatigue-Inertia and Confusion-Bewilderment than norms.Conclusions: The findings of this study revealed the physical, physiological, and psychological characteristics in taekwondo. The results of the tests could be useful for performance assessment of taekwondo players.