Validity of the relative fat mass pediatric index (RFMp) for the analysis of body composition in physically active youths at different stages of biological maturation.

BACKGROUND: The paediatric relative fat mass (RFMp) index was valid for analysis of percent body fat (BF%). However, the validation did not consider biological maturation (BM) stages. The present study aimed to verify the validity of the RFMp index in the estimation of BF% in children and adolescents of both sexes at different stages of BM. METHODS: A cross-sectional study was conducted with a sample of 146 young (males: 64.5%. females: 35.5%. age: 13.0 ± 2.2 years) practising sports modalities. We tested the validity of four RFMp equations (1: for boys aged 8-14 years; 2: for girls aged 8-14 years; 3: for both sexes aged 8-14 years; and 4: for both sexes aged 15-19 years) to analyse BF% using dual-energy X-ray absorptiometry as a reference method. BM was analysed by peak height velocity (PHV). Thus, we created subgroups by BM stage (pre-PHV, circum-PHV and post-PHV). RESULTS: Analyses of agreement between methods showed that only the RFMp-3 equation was reliable to analyse BF% in subjects of both sexes aged 8-14 years at the circum-PHV BM stage (proportion bias 95% confidence interval = -0.3 to 0.5, p = 0.7. concordance correlation coefficient = 0.3; validity = 0.9). CONCLUSIONS: The RFMp equation developed for the paediatric population of both sexes aged 8-14 years was valid for predicting BF% in children and adolescents of both sexes at the Circum-PHV stage of the BM.

Reliability of biological maturation analyses performed by equations predicting skeletal age and peak height velocity with hand and wrist X-ray results.

BACKGROUND: Hand-wrist radiography is the gold standard for the assessment of skeletal age (SA) and the assignment of biological maturation (BM) status. However, its practical use in the field is questioned, prompting the development of anthropometric equations to estimate BM. However, there is no consensus on the reliability of these equations in relation to hand-wrist X-rays. OBJECTIVE: To test the reliability of the BM estimated from predictive equations with the results of hand-wrist X-rays. METHODS: One-hundred forty-four young athletes (38%-males, 62%-females; 12.3 ± 1.4 years) were recruited. SA was assessed by analyzing X-rays of the hand-wrist using the Greulich-Pyle protocol. SA was predicted using the anthropometric equations of Cabral and Macêdo. By subtracting chronological age from SA, a measure of BM or biological age (BA) was computed. In addition, a BA of years from peak height velocity (PHV) was predicted using the anthropometric equations of Mirwald and Moore. RESULTS: Relative to X-ray, Cabral's equations showed high reliability in estimating BM in both sexes (p < .0001) while Macêdo's equations showed substantial reliability or males (p < .0001) only. Mirwald and Moore's equations showed weak reliability (p < .05 and p = .043, respectively). CONCLUSION: The prediction of SA using anthropometric equations was found to be reliable in categorizing individuals as late, synchronized, and/or early maturers in both sexes. However, the predictive equations of years from PHV only reliably categorized late and synchronized maturation stages in males and the synchronized maturers in females.

Body adiposity index to analyze the percentage of fat in young men aged between 7 and 17 years.

BACKGROUND: The body adiposity index (BAI), uses anthropometry to estimate percent body fat (%F). However, previous studies have shown that the BAI has limited accuracy for children and adolescents. OBJECTIVE: We propose to develop and validate an adjusted BAI for use in male children and adolescents from 7 to 17 years of age. METHODS: The sample consisted of 141 physically active male children and adolescents (age: 12.5 ± 2.14). The %F was determined by X-ray dual energy absorptometry equipment (DXA) as the standard method and by BAI, using an equation that uses height and hip circumference. Arithmetic modeling was used to adjust the structure of the BAI mathematical model. RESULTS: The BAI arithmetic adjustment was successful, resulting in the mathematical model named in the present study of adjusted body adiposity index (BAIADJ ). BAI and BAIADJ correlated with DXA (r ≤ .70, p < .001). Regression analyzes indicate that, BAI (CI 95% ß: [1.35; 1.90], p < .0001) and BAIADJ (CI 95% ß: [1.40; 1.90], p < .0001) have the potential to estimate %F. BAI pointed out a difference in relation to DXA (p = .04). While there was no difference between BAIADJ and DXA (p = .1). There was a proportion bias of 13.2% for BAI (p < .05), but not for BAIADJ (p > .05). CONCLUSION: The adjusted model of the body adiposity index proves to be an effective tool for the analysis of the fat percentage in young males. In addition, it demonstrated significant degrees of agreement and validity in relation to DXA.

Effects of ibuprofen during 42-km trail running on oxidative stress, muscle fatigue, muscle damage and performance: a randomized controlled trial.

Up to 75% of marathon runners ingest non-steroidal anti-inflammatory drugs (NSAIDs) during competition. Despite the doubt whether or not they contribute to performance, the effect of NSAID in endurance sports is unclear. We evaluated the effect of ibuprofen (IBU) use on oxidative stress, muscle damage, physical performance, and vertical jump of runners participating in a 42-km-trail running. The sample consisted of 12 men randomly divided into 2 groups: a placebo group (placebo) and an ibuprofen group (IBG). A 400-mg IBU capsule was administered to the IBG 15 min prior to the start of the trial and during the course after 5 h. In the intergroup analysis, placebo 70.1% increase (p < 0.0001; Cohen's d = 4.77) of the thiobarbituric acid reactive substances (TBARS); the IBG exhibited a 31.46% increase of the sulphhydryl groups (SH) (p = 0.024, Cohen's d = 0.27), 55% of squat jump (SJ) (p < 0.01; Cohen's d = 1.41) with no significant effect on creatine kinase (CK), pace, speed, and finish time. In summary, IBU had positive evidence on oxidative stress and muscle fatigue, but had no effect on physical performance and muscle damage.

Evaluation of the body adiposity index against dual-energy X-ray absorptiometry for assessing body composition in children and adolescents.

BACKGROUND: It is important to clarify the association of lean and fat mass between children and adolescents considering the rising prevalence of overweight and obesity in this age group. The aim of this study was to verify the association between the body adiposity index (BAI) and dual-energy X-ray absorptiometry (DXA) methods for analyzing body composition, as well as analyzing the validity of BAI to verify the percentage of fat in children and adolescents. METHODS: The sample was composed of 106 children and adolescents, 44 females (age: 11.5 ± 1.8 years) and 62 evils (13.6 ± 2.6 years). The body fat (%F) was measured using DXA and the doubly indirect BAI body fat estimation technique. RESULTS: The BAI and DXA estimates of %F were strongly correlated (boys: r = .71, P < .0001; girls: r = .72, P < .0001). The linear regression analyses showed that BAI is significant to estimate the %F in total sample (P < .0001). For boys, the %F analyzes performed by BAI and DXA did not show any differences when compared (P = .2). In addition, BAI pointed out a significant proportion bias for both sexes (P < .0001), which suggests its inefficiency in the analysis of %F. CONCLUSIONS: BAI and DXA correlate; however, there is low reliability and a high proportion bias for the analysis of %F by BAI.

Effect of Ibuprofen on Muscle, Hematological and Renal Function, Hydric Balance, Pain, and Performance During Intense Long-Distance Running.

de Souza, RF, de Matos, DG, Ferreira, ARP, Chilibeck, P, Barros, NdA, de Oliveira, AS, Cercato, LM, da Silva, DS, and Aidar, FJ. Effect of ibuprofen on muscle, hematological and renal function, hydric balance, pain, and performance during intense long-distance running. J Strength Cond Res 34(7): 2076-2083, 2020-The aim of this study was to investigate the effect of prophylactic use of nonsteroidal anti-inflammatory drugs (i.e., ibuprofen) on physical performance, vertical jump, muscle biomarkers, liver, kidney, acute pain, and hydration status of participants in the 42-km Trail Running Challenge, a long-distance race integrated over mountain routes. The sample consisted of 20 men randomly divided into 2 groups: a control group (CG) and an experimental group (EG), with 12 completing the race (41.1 ± 8.8 years; 75.7 ± 12.1 kg) and included in the final analysis. The EG were administered an ibuprofen capsule (400 mg) 15 minutes before the beginning of the race and again after 5 hours of racing if the route was not yet completed. There were significant time main effects for creatine kinase (p = 0.001; f Cohen = 0.25), lactate dehydrogenase (p < 0.001; f Cohen = 2.05), aspartate aminotransferase (p = 0.002; f Cohen = 1.53), creatinine (p = 0.002; f Cohen = 2.24), urea (p = 0.001; f Cohen = 2.25), heart rate (p < 0.001; f Cohen = 4.88), and pain scores (p < 0.001; f Cohen = 1.93) all of which increased during the race. There was a group × time interaction for squat jump, which significantly decreased only in the CG (p = 0.045; f Cohen = 2.17). This may have been related to increased frequency of pain reported after the race in the gastrocnemius of the CG compared with the EG (p ≤ 0.05). It was concluded that ibuprofen intake did not reduce muscle damage during the competition but maintained leg muscular power performance (i.e., vertical jump), possibly by reducing gastrocnemius muscle pain.

Comparison of Post-Exercise Hypotension Responses in Paralympic Powerlifting Athletes after Completing Two Bench Press Training Intensities.

Background and objective: Post-exercise hypotension, the reduction of blood pressure after a bout of exercise, is of great clinical relevance. Resistance exercise training is considered an important contribution to exercise training programs for hypertensive individuals and athletes. In this context, post-exercise hypotension could be clinically relevant because it would maintain blood pressure of hypertensive individuals transiently at lower levels during day-time intervals, when blood pressure is typically at its highest levels. The aim of this study was to compare the post-exercise cardiovascular effects on Paralympic powerlifting athletes of two typical high-intensity resistance-training sessions, using either five sets of five bench press repetitions at 90% 1 repetition maximum (1RM) or five sets of three bench press repetitions at 95% 1RM. Materials and Methods: Ten national-level Paralympic weightlifting athletes (age: 26.1 ± 6.9 years; body mass: 76.8 ± 17.4 kg) completed the two resistance-training sessions, one week apart, in a random order. Results: Compared with baseline values, a reduction of 5-9% in systolic blood pressure was observed after 90% and 95% of 1RM at 20-50 min post-exercise. Furthermore, myocardial oxygen volume and double product were only significantly increased immediately after and 5 min post-exercise, while the heart rate was significantly elevated after the resistance training but decreased to baseline level by 50 min after training for both training conditions. Conclusions: A hypotensive response can be expected in elite Paralympic powerlifting athletes after typical high-intensity type resistance-training sessions.

A Randomized Trial Investigating the Influence of Strength Training on Quality of Life in Ischemic Stroke.

BACKGROUND: Strength training post stroke is widely acknowledged as an important part of a rehabilitation program. Muscle strength has been shown to be a significant contributor to physical disability after stroke, which in turn has an immense impact on the reintegration of patients into society, affecting their quality of life. OBJECTIVE: This was a randomized intervention trial to determine the effect of a resistance training program on the quality of life in patients with stroke. METHODS: An experimental group (EG), consisting of 11 subjects aged 51.7 ± 8.0 years, and a control group (CG), consisting of 13 subjects aged 52.5 ± 7.7 years, were studied before and after 12 weeks. EG underwent 12 weeks of strength training three times a week. The CG did not undergo strength training during the 12-week study period. RESULTS: There was a significant increase in quality of life from pre-test to post-test (Δ% = 21.47%; p = 0.021) in EG. There were significant differences in all indicators of quality of life between groups at 12 weeks. There were greater gains in strength in EG than in CG (p ≤ 0.05). There was a negative correlation between the strength gains as determined with the 1RM test and the quality of life, especially in lower limb exercises. CONCLUSION: The results of this study indicate that there was an improvement in the measures of strength in EG, and that there was a correlation between improvements in strength and quality of life in these patients who had previously suffered a stroke at least one year prior to study.

Relative age effect in elite Brazilian athletes in different combat sports: an observational study.

Background: The relative age effect (RAE) suggests that, due to maturity, young athletes born in the first quartiles of the year may have advantages over those born in the last quartiles of the year. Thus, it is important to evaluate the RAE in different sports and to consider the particularities of the subdivisions of the sports categories. Objective: To analyze the RAE in the top 20 of the Brazilian rankings in different combat sports. Methods: Observational study that analyzed the national databases for the year 2019 (from categories U-11 to U-18) made publicly available by the Brazilian confederations of karate, taekwondo and fencing. We obtained data on date of birth, age category and body weight of all modalities, type of fencing competition weapon (Epee, Foie and Saber) and type of karate modality (kumite and kata) from the top 20 places in each ranking. The final sample consisted of 1,486 athletes (Age: 14.2 ± 2.3. Male-53.2%. Female-46.8%). To identify the RAE, we performed a contingency analysis and compared the results between the sexes within the same sport. Results: There was RAE in the U-11, U-12, U-15 and U-17 fencing categories (p < 0.05), being higher in the female categories (p < 0.05). The RAE was higher for males in the Epee test, and similar between the sexes for the Saber and Foie tests. In karate, RAE occurred in categories U-14 and U-16 (p < 0.05), being higher in males (p < 0.05). The RAE was similar between the sexes in the kumite modality (p < 0.05). There was no RAE for the kata modality in karate (p > 0.05) and for the Taekwondo categories (p > 0.05). Conclusion: The results showed the existence of a relative age effect in elite athletes ranked (top 20 places in each ranking) only for the sport of fencing and karate kumite.

Relative age effects on speed trials in Brazilian athletics.

BACKGROUND: Relative age effect (RAE) is a concept related to the possible advantage that older athletes would have over younger ones within the same category. Although many studies have approached this subject in individual sports, there are few clippings by events within the sport. More detailed analyses are necessary for a better understanding of how RAE behaves in sports, especially in athletics, the subject of this study. The objective of this study was to analyze the RAE on speed in track and field events as a whole, separating the flat races from the hurdles races. METHODS: The Brazilian Ranking of Brazilian Athletics Confederation was used for data analysis, and the sample was composed of the 50 best-placed marks in the ranking of speed events in athletics in the categories Under(U)-16 and U-18 (female and male). Statistical analysis was calculated by chi-square, and the effect size was checked by Cramer's V. Likelihood-ratio test (L-Ratio) assessed the probability of the RAE occurring in the total sample and by age groups. RESULTS: In the total sample the results pointed to the emergence of RAE in males in both categories (U-16: p < 0.001; V: 0.13; L-Ratio: 3.64, U-18: p < 0.001; V: 0.13; L-Ratio: 3.80), whereas in females no such effect was found in any category (U-16: p = 0.6; V: 0.09; L-Ratio: 0.09, U-18: p = 0.6; V: 0.07; L-Ratio: 0.12). When the results were separated by type of event, there was only a RAE in the shallow event in the U-18 female category (p = 0.3; V: 0.11; L-Ratio: 8.72). CONCLUSION: The results allow us to conclude that there is a RAE in the speed trials of Brazilian athletics in the U16 and U18 categories for men, while this effect appears only in the shallow trials of the U18 category for women, indicating that the RAE has incidence when there is more participation and competition in the sport.

Evaluating the Asymmetry of Muscle Activation and Strength in Paralympic Powerlifting Athletes.

BACKGROUND: Strength training is a complex task, as it requires a combination of many variables. In paralympic powerlifting (PP) asymmetries for the evaluation of activation, and static force indicators have been increasingly studied. OBJECTIVE: To investigate the asymmetries in the strength and muscle activation indicators, before and after a training session of PP athletes. METHODOLOGY: Twelve elite athletes from the PP participated in the study, and asymmetry was evaluated through surface electromyography (sEMG) and static strength indicators. Evaluations were made before and after a protocol of five series of five repetitions (5 × 5), with 80% of 1-Maximum Repetition (1RM). RESULTS: In the pectoral muscles, there were differences in the non-dominant limbs between the before and after in the sEMG. There were differences in the pectoralis muscle in the non-dominant limb between moments before (110.75 ± 59.52%) and after (130.53 ± 98.48%, p < 0.001), and there was no difference in triceps activation. In the Maximum Isometric Strength (MIF), there was a difference in the non-dominant limb between before (710.36 ± 129.36) and after (620.27 ± 69.73; p < 0.030). There was a difference before in the dominant (626.89 ± 120.16; 95% CI 550.55-703.24) and non-dominant (710.36 ± 129.36; p = 0.011) limbs. There was no difference in time to MIF. CONCLUSION: PP athletes showed small levels of asymmetry before and after training, and adaptation to training tends to promote fewer asymmetries.

Integrated Dynamic Autonomic and Cardiovascular Regulation during Postural Transitions in Older Adults Living with Frailty: A Systematic Review Protocol.

Older adults often experience episodes of a sudden drop in blood pressure when standing, known as orthostatic hypotension (OH). OH is associated with an increased risk of life-threatening health problems, falls, and death. Although OH has been studied in older adults, the integrated dynamic autonomic and cardiovascular regulation during postural transitions in older adults with frailty remains scarce and poorly understood. The primary aim of this systematic review is to determine the association between how active (e.g., lie-to-stand) and passive (head-up tilt) postural transitions affect the dynamic integrated autonomic and cardiovascular regulatory responses, comparing older adults with different levels of frailty (non-frail, pre-frail, or frail). A second aim is to perform a meta-analysis to compare autonomic and cardiovascular responses during active postural transitions in non-frail, pre-frail, and frail older adults. The systematic review will be outlined according to the Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols. The meta-analysis will generate estimates of the comparative autonomic and cardiovascular responses after active postural transitions in adults who are non-frail, pre-frail, and frail. This systematic review will provide critical information on how integrated dynamic autonomic and cardiovascular regulation occurs during postural transitions in older adults with different frailty statuses.

Force-velocity relationship in Paralympic powerlifting: two or multiple-point methods to determine a maximum repetition.

BACKGROUND: Due to the absence of evidence in the literature on Paralympic Powerlifting the present study investigated various methods to assess bench press maximum repetition and the way each method influences the measurement of minimum velocity limit (MVT), load at zero velocity (LD0), and force-velocity (FV). OBJECTIVE: To evaluate the precision of the multi-point method using proximal loads (40, 50, 60, 70, 80, and 90% of one repetition maximum; 1RM) compared to the four-point method (50, 60, 70, and 80% of 1RM) and the two-point method using distant loads (40 and 80% and 50 and 80% of 1RM) in in the MVT, LD0, and FV, in bench press performed by Paralympic Powerlifters (PP). METHODS: To accomplish this, 15 male elite PP athletes participated in the study (age: 27.7 ± 5.7 years; BM: 74.0 ± 19.5 kg). All participants performed an adapted bench press test (free weight) with 6 loads (40, 50, 60, 70, 80, and 90% 1RM), 4 loads (50, 60, 70, and 80% 1RM), and 2 loads (40-80% and 50-80% 1RM). The 1RM predictions were made by MVT, LD0, and FV. RESULTS: The main results indicated that the multiple (4 and 6) pointsmethod provides good results in the MVT (R2 = 0.482), the LD0 (R2 = 0.614), and the FV (R2 = 0.508). The two-point method (50-80%) showed a higher mean in MVT [1268.2 ± 502.0 N; ICC95% 0.76 (0.31-0.92)], in LD0 [1504.1 ± 597.3 N; 0.63 (0.17-0.86)], and in FV [1479.2 ± 636.0 N; 0.60 (0.10-0.86)]. CONCLUSION: The multiple-point method (4 and 6 points) and the two-point method (40-80%) using the MVT, LD0, and FV all showed a good ability to predict bench press 1RM in PP.

Evaluation of Ibuprofen Use on the Immune System Indicators and Force in Disabled Paralympic Powerlifters of Different Sport Levels.

Background: Paralympic powerlifting (PP) training is typically intense and causes fatigue and alterations in the immune system. Objective: To analyze whether IBU would affect performance and the immune system after training in PP. Methodology: 10 athletes at the national level (NL) and 10 at the regional level (RL) participated in the study, where force and blood indicators were evaluated after training. The study took place over three weeks: (1) familiarization and (2 and 3) comparison between recovery methods, with ibuprofen or placebo (IBU vs. PLA), 800 mg. In the evaluation of the force, the peak torque (PT), fatigue index (FI), and blood immune system biomarkers were analyzed. The training consisted of five sets of five repetitions with 80% of one maximum repetition (5 × 5, 80% 1RM) on the bench press. Results: The PT at the national level using IBU was higher than with PLA (p = 0.007, η2p = 0.347), and the FI in the NL was lower with IBU than with PLA (p = 0.002, η2p = 0.635), and when comparing the use of IBU, the NL showed less fatigue than the regional level (p = 0.004, η2p = 0.414). Leukocytes, with the use of IBU in the NL group, were greater than in the RL (p = 0.001, η2p = 0.329). Neutrophils, in the NL with IBU, were greater than in the RL with IBU and PLA (p = 0.025, η2p = 0.444). Lymphocytes, in NL with IBU were lower than in RL with IBU and PLA (p = 0.001, η2p = 0.491). Monocytes, in the NL with IBU and PLA, were lower than in the RL with IBU (p = 0.049, η2p = 0.344). For hemoglobin, hematocrit, and erythrocyte, the NL with IBU and PLA were higher than the RL with IBU and PLA (p < 0.05). Ammonia, with the use of IBU in the NL, obtained values higher than in the RL (p = 0.007), and with the use of PLA, the NL was higher than the RL (p = 0.038, η2p = 0.570). Conclusion: The training level tends to influence the immune system and, combined with the use of the IBU, it tends to improve recovery and the immune system.

Comparison of the Local Temperature, Lactate and Glucose After Three Different Strength Training Methods.

This study aimed to evaluate the local temperature, lactate, and blood glucose in three strength training methods. The study included 12 male subjects; (22.15 ± 5.77 years, 76.85 ± 9.15 kg, 1.72 ± 0.09 m), with minimum of 12 months of strength training experience, and all participated in the three training methods: the occlusion training (Kaatsu); the tension training (Tension); and the traditional training (Traditional). The Kaatsu training consisted in 3 sets of 10RM with occlusion device in both arms inflated to a 130% occlusion pressure. In addition, the tension method was performed with 30% of 1RM and the traditional training, consisted in 10 repetitions with 80% RM. Regarding the temperature variation, differences were observed between the Kaatsu and Traditional methods in relation to Tension (p = .049, η 2 p = 0.187). While for blood glucose (p = .351, η 2 p = 0.075) and lactate (p = .722, η 2 p = 0.022) there were no differences between the methods. Regarding the temperature (°C) measured by thermography and asymmetry, the right side showed a decrease in the post-test, in relation to the pre-test, in all methods (p < .05, η 2 p > 0.150). The left (p = .035, η 2 p = 0.301) and right (p = .012, η 2 p = 0.324) sides showed a decrease in temperature, in the post-test in relation to the pre-test, in the Kaatsu and traditional method. In asymmetry, the three methods showed an increase in the post-test in relation to the pre-test (p = .042, η 2 p = 0.158). In conclusion, tension method seems to stimulate greater heat production than the other methods. This information can help coaches to choose among these training methods according to the desired physiological response.

Two Weekly Sessions of High-Intensity Interval Training Improve Metabolic Syndrome and Hypertriglyceridemic Waist Phenotype in Older Adults: A Randomized Controlled Trial.

Background: Exercise training provides physiological benefits for maintaining good health. A common exercise strategy is high-intensity interval training (HIIT). HIIT may alleviate metabolic syndrome (MetS) and hypertriglyceridemic waist (HTGW) phenotype, but remains largely unstudied in ageing participants. The aim of this research was to investigate the impact of 2 weekly HIIT sessions on MetS markers and HTGW-related factors in older adults. Methods: In this randomized controlled trial, 140 older men and women were randomized into two groups, the experimental group (EG), and the control group (CG). The EG performed 2 weekly sessions of HIIT during 12 weeks. HIIT sessions consisted of 40 min treadmill running/walking: a 10 min warm-up at 50%-60% of maximum heart rate (HRmax), followed by 10 sets of 1 min bouts at 85%-90% of HRmax interspersed with 1 min walking at self-selected pace (totaling 20 min), and 10 min cool-down walking at self-selected pace. The CG did not perform any type of intense exercise during the intervention period. Results: Participants in the EG of both sexes decreased MetS, HTGW, blood pressure, cholesterol, and glycemia (P < 0.05). After training, the number of hypertensive men decreased by 100% and women by 70%. There was a 75% reduction in women with diabetes, a 100% reduction in MetS indicators and over 80% reduction in HTGW in participants of both sexes. Conclusion: Two weekly sessions of HIIT proved to be feasible and effective to induce clinically relevant improvements in MetS and HTGW indicators.

The 6-week Effects of HIIT on Biomarkers of Tissue and Oxidative Damage in Wistar Rats Previously Supplemented with Pyridoxine.

We aimed to analyze the effects of long high-intensity interval training (HIIT) associated with pyridoxin supplementation on tissue and oxidative injury markers in animals. Male Wistar rats were divided into three groups (n = 8): sedentary (GS), HIIT (GH), and HIIT + pyridoxine (GHP). The HIIT comprised 18 sessions of 7 repetitions of 2min × 2min rest, 3 times per week. Pyridoxine was administered to the GHP group 1h before the exercise. The Thiobarbituric acid reactive substances (TBARS) and sulfhydryl group (SH) were analyzed as markers of oxidative stress and CK, LDH, ALT and AST as tissue lesions. There was an increase in the correlation between CK and LDH of 172.86% and 268.83% in the GH group compared with the GS group, respectively. There was a reduction in CK (34.37%) and LDH (34.74%) compared with the GH group, which had an increase of 229.03% in ALT. Pyridoxine supplementation reduced ALT by 80.62% in the GHP group compared with no-supplementation GH group. In addition, there was a reduction in plasma MDA (52.92%), liver (20.30%) and cardiac (22.06%) tissues in GHP compared to GH. It was possible to conclude that administration of pyridoxine attenuated oxidative stress, and tissue injuries induced by HIIT.

The 6-week Effects of HIIT on Biomarkers of Tissue and Oxidative Damage in Wistar Rats Previously Supplemented with Pyridoxine.

We aimed to analyze the effects of long high-intensity interval training (HIIT) associated with pyridoxin supplementation on tissue and oxidative injury markers in animals. Male Wistar rats were divided into three groups (n = 8): sedentary (GS), HIIT (GH), and HIIT + pyridoxine (GHP). The HIIT comprised 18 sessions of 7 repetitions of 2min × 2min rest, 3 times per week. Pyridoxine was administered to the GHP group 1h before the exercise. The Thiobarbituric acid reactive substances (TBARS) and sulfhydryl group (SH) were analyzed as markers of oxidative stress and CK, LDH, ALT and AST as tissue lesions. There was an increase in the correlation between CK and LDH of 172.86% and 268.83% in the GH group compared with the GS group, respectively. There was a reduction in CK (34.37%) and LDH (34.74%) compared with the GH group, which had an increase of 229.03% in ALT. Pyridoxine supplementation reduced ALT by 80.62% in the GHP group compared with no-supplementation GH group. In addition, there was a reduction in plasma MDA (52.92%), liver (20.30%) and cardiac (22.06%) tissues in GHP compared to GH. It was possible to conclude that administration of pyridoxine attenuated oxidative stress, and tissue injuries induced by HIIT.

Relationship of Biological Maturation with Muscle Power in Young Female Athletes.

There is still no consensus on how biological maturation (BM) affects the muscle power of upper and lower limbs in young people. The objective was to verify associations between BM and muscle power, as well as to compare the muscle power of upper (ULP) and lower limbs (LLP) among young athletes in different stages of BM. The sample consisted of 79 female athletes (10.9 ± 1.11 years old). Regarding BM, the sample was divided into three groups: delayed BM, synchronized BM, and accelerated BM. BM was identified by subtracting chronological age from bone age (BA). BA was measured by a mathematical model based on anthropometry. The muscular power of the upper limbs was analyzed by the medicine ball launch test, and that of the lower limbs was analyzed by the countermovement jump on a force platform. BM and BA correlated with ULP (BA: r =0.74; BM: r =0.65) and LLP (BA: r = 0.50; BM: r =0.41). In the comparisons of the tests of ULP and LLP, the groups with synchronized and accelerated BM were superior to the group with delayed BM. The advance of BM is associated with the ULP and LLP, as well as the advance of the BM affects muscle power in young female athletes. This occurs due to the increase in body mass resulting from the advancement of BM, which may favor the predominance of lean body mass, assisting in the production of muscle strength.

Lean mass and biological maturation as predictors of muscle power and strength performance in young athletes.

BACKGROUND: The biological maturation (BM) analyzed by peak height velocity (PHV) and bone age (BA), and lean body mass has been associated with the strength and muscle power of young athletes. However, the ability of BM (PHV and BA) and LM markers to predict muscle strength and power in young athletes remains uncertain. OBJECTIVE: The Aim was determine the predicting power of BM markers (PHV and BA) and LM in relation to muscle power of upper and lower limbs and muscle strength of upper limbs in adolescent athletes at puberty. METHODS: Ninety-two adolescent athletes (both sexes; age 12.4 ± 1.02 years) were assessed for body composition by dual-energy X-ray absorptiometry (DXA). Power of upper limbs (ULP), force handgrip (HG), vertical jump (VJ) and countermovement jump (CMJ) were recorded. BM was predicted by mathematical models to estimate PHV and BA. Multilayer artificial neural network analyses (MLP's) were used to determine the power of prediction of LM, PHV and BA on muscle power and strength of upper- and lower-limbs of the athletes. RESULTS: LM, BA and PHV were associated with HG (r>0.74, p<0.05) and ULS (r>0.60, p<0.05) in both sexes. In both sexes BA was associated with VJ (r>0.55, p<0.05) and CMJ (r>0.53, p<0.05). LM indicated associations (r>0.60, p<0.05) with BA and with PHV (r<0.83, p<0.05) in both sexes. MLP's analysis revealed that the LM provides > 72% of probability to predict the muscle power of upper- and lower-limbs, and the strength of the upper limbs; whereas PHV provides > 43% and bone age >64% in both female and male adolescent athletes. CONCLUSION: We identified that, like PHV and BA, LM is a strong predictor of low cost of both upper limbs muscle strength and upper and lower limbs power in adolescent athletes.