Effect of strength training versus raloxifene on bone weight, blood glucose, lipid and antioxidant profile in ovariectomized rats

We compared the effect of the treatment with strength training (ST) and raloxifene (RALOX) on bone weight, blood glucose, lipid, and antioxidant profile in ovariectomized rats. Twenty-four Wistar rats were distributed into four groups: ovariectomy + VEHICLE (control); ovariectomy + RALOX; ovariectomy + ST; ovariectomy + RALOX + ST. Thirty days after ovariectomy, the animals underwent the treatment with RALOX (750 µcg day-1) and/or ST (three sessions week-1). Thirty days after, all groups were scarified, tibia and femur were weighed, and the blood was collected for analysis of the lipid profile, glucose, and antioxidants catalase (CAT) and glutathione (GSH). The ST group showed greater femur weight (0.82 ± 0.18 g) and RALOX + ST had greater tibia weight (0.61± 0.17 g) than CONTROL with femur weight of 0.65 ± 0.08 g and tibia of 0.49 ± 0.08 g with no differences between treatments (p > 0.05). ST group showed significantly higher catalase (181.7 ± 15.4 µM g-1) compared to the other groups. In contrast, the GSH value was lower in ST group (89.2 ± 8.1 µM g-1) compared to RALOX (175.9 ± 17.1 µM g-1) and RALOX + ST (162.8 ± 12.1 µM g-1), but the values of these two groups did not differ from CONTROL(115.3 ± 21.1 µM g-1). Total cholesterol did not differ between groups (p > 0.05), but exercise alone(54.3 ± 2.5 mg dL-1) or with RALOX (53.0 ± 1.5 mg dL-1) resulted in higher HDL cholesterol than CONTROL (45.5 ± 2.5 mg dL-1). Only RALOX+ST presented lower glucose (140.3 ± 9.7 mg dL-1) values than CONTROL (201.7 ± 30.6 mg dL-1). In conclusion, ST promotes similar benefits on bone and metabolic parameters compared to pharmacological treatment in ovariectomized rats.(AU)

Influence of Alpha-Actinin-3 R577X Polymorphism on Muscle Damage and the Inflammatory Response after an Acute Strength Training Session.

The objective of this study was to verify the influence of the ACTN3 R577X polymorphism on muscle damage and the inflammatory response after an acute strength training (ST) session. Twenty-seven healthy male individuals (age: 25 ± 4.3 years) participated in the study, including 18 RR/RX and 9 XX individuals. The participants were divided into two groups (RR/RX and XX groups) and subjected to an acute ST session, which consisted of a series of leg press, leg extension machine, and seated leg curl machine. The volunteers were instructed to perform the greatest volume of work until concentric muscle failure. Each volunteer's performance was analyzed as the load and total volume of training, and the blood concentrations of C-C motif chemokine ligand 2 (CCL2), interleukin-8 (IL-8), creatine kinase (CK), lactate dehydrogenase (LDH), myoglobin, testosterone, and cortisol were measured before the ST session and 30 min and 24 h postsession. The ACTN3 R577X polymorphism effect was observed, with increased concentrations of CCL2 (p < 0.01), IL-8 (p < 0.01), and LDH (p < 0.001) in XX individuals. There was an increase in the concentration of CK in the RR/RX group compared to XX at 24 h after training (p > 0.01). The testosterone/cortisol ratio increased more markedly in the XX group (p < 0.001). Regarding performance, the RR/RX group presented higher load and total volume values in the training exercises when compared to the XX group (p < 0.05). However, the XX group presented higher values of delayed onset muscle soreness (DOMS) than the RR/RX group (p < 0.05). The influence of ACTN3 R577X polymorphism on muscle damage and the inflammatory response was observed after an acute ST session, indicating that the RR/RX genotype shows more muscle damage and a catabolic profile due to a better performance in this activity, while the XX genotype shows more DOMS.

Volume Load Rather Than Resting Interval Influences Muscle Hypertrophy During High-Intensity Resistance Training.

ABSTRACT: Longo, AR, Silva-Batista, C, Pedroso, K, de Salles Painelli, V, Lasevicius, T, Schoenfeld, BJ, Aihara, AY, de Almeida Peres, B, Tricoli, V, and Teixeira, EL. Volume load rather than resting interval influences muscle hypertrophy during high-intensity resistance training. J Strength Cond Res 36(6): 1554-1559, 2022-Interset rest interval has been proposed as an important variable for inducing muscle mass and strength increases during resistance training. However, its influence remains unclear, especially when protocols with differing intervals have equalized volume. We aimed to compare the effects of long (LI) vs. short rest interval (SI) on muscle strength (one repetition maximum [1RM]) and quadriceps cross-sectional area (QCSA), with or without equalized volume load (VL). Twenty-eight subjects trained twice a week for 10 weeks. Each subject's leg was allocated to 1 of 4 unilateral knee extension protocols: LI, SI, SI with VL -matched by LI (VLI-SI), and LI with VL-matched by SI (VSI-LI). A 3-minute rest interval was afforded in LI and VSI-LI protocols, while SI and VLI-SI employed a 1-minute interval. All subjects trained with a load corresponding to 80% 1RM. One repetition maximum and QCSA were measured before and after training. All protocols significantly increased 1RM values in post-training (p < 0.0001; LI: 27.6%, effect size [ES] = 0.90; VLI-SI: 31.1%, ES = 1.00; SI: 26.5%, ES = 1.11; and VSI-LI: 31.2%, ES = 1.28), with no significant differences between protocols. Quadriceps cross-sectional area increased significantly for all protocols in post-training (p < 0.0001). However, absolute changes in QCSA were significantly greater in LI and VLI-SI (13.1%, ES: 0.66 and 12.9%, ES: 0.63) than SI and VSI-LI (6.8%, ES: 0.38 and 6.6%, ES: 0.37) (both comparisons, p < 0.05). These data suggest that maintenance of high loads is more important for strength increases, while a greater VL plays a primary role for hypertrophy, regardless of interset rest interval.

Application and side effects of blood flow restriction technique: A cross-sectional questionnaire survey of professionals.

ABSTRACT: The physiological benefits of applying blood flow restriction (BFR) in isolation or in the presence of physical exercise have been widely documented in the scientific literature. Most investigations carried out under controlled laboratory conditions have found the technique to be safe. However, few studies have analyzed the use of the technique in clinical settings.To analyze how the BFR technique has been applied by professionals working in the clinical area and the prevalence of side effects (SEs) resulting from the use of this technique.This is a cross-sectional study. A total of 136 Brazilian professionals who perform some function related to physical rehabilitation, sports science, or physical conditioning participated in this study. Participants answered a self-administered online questionnaire consisting of 21 questions related to the professional profile and methodological aspects and SEs of the BFR technique.Professionals reported applying the BFR technique on individuals from different age groups from youth (≤18 years; 3.5%) to older adults (60-80 years; 30.7%), but mainly on people within the age group of 20 to 29 years (74.6%). A total of 99.1% of the professionals coupled the BFR technique with resistance exercise. Their main goals were muscle hypertrophy and physical rehabilitation. The majority (60.9%) of interviewees reported using BFR in durations of less than 5 minutes and the pressure used was mainly determined through the values of brachial blood pressure and arterial occlusion. Moreover, 92% of professionals declared observing at least 1 SE resulting from the BFR technique. Most professionals observed tingling (71.2%) and delayed onset of muscle soreness (55.8%). Rhabdomyolysis, fainting, and subcutaneous hemorrhaging were reported less frequently (1.9%, 3.8%, and 4.8%, respectively).Our findings indicate that the prescription of blood flow restriction technique results in minimal serious side effects when it is done in a proper clinical environment and follows the proposed recommendations found in relevant scientific literature.

Resistance Training Safety during and after the SARS-Cov-2 Outbreak: Practical Recommendations.

In December of 2019, there was an outbreak of a severe acute respiratory syndrome caused by the coronavirus 2 (SARS-CoV-2 or COVID-19) in China. The virus rapidly spread into the whole world causing an unprecedented pandemic and forcing governments to impose a global quarantine, entering an extreme unknown situation. The organizational consequences of quarantine/isolation are absence of organized training and competition, lack of communication among athletes and coaches, inability to move freely, lack of adequate sunlight exposure, and inappropriate training conditions. The reduction of mobility imposed to contain the advance of the SARS-Cov-2 pandemic can negatively affect the physical condition and health of individuals leading to muscle atrophy, progressive loss of muscle strength, and reductions in neuromuscular and mechanical capacities. Resistance training (RT) might be an effective tool to counteract these adverse consequences. RT is considered an essential part of an exercise program due to its numerous health and athletic benefits. However, in the face of the SARS-Cov-2 outbreak, many people might be concerned with safety issues regarding its practice, especially in indoor exercise facilities, such as gyms and fitness centers. These concerns might be associated with RT impact in the immune system, respiratory changes, and contamination due to equipment sharing and agglomeration. In this current opinion article, we provide insights to address these issues to facilitate the return of RT practices under the new logistical and health challenges. We understand that RT can be adapted to allow its performance with measures adopted to control coronavirus outbreak such that the benefits would largely overcome the potential risks. The article provides some practical information to help on its implementation.

Suspension training vs. traditional resistance training: effects on muscle mass, strength and functional performance in older adults.

PURPOSE: We compared the effects of suspension training (ST) with traditional resistance training (TRT) on muscle mass, strength and functional performance in older adults. METHODS: Forty-two untrained older adults were randomized in TRT, ST (both performed 3 sets of whole body exercises to muscle failure) or control group (CON). Muscle thickness (MT) of biceps brachii (MTBB) and vastus lateralis (MTVL), maximal dynamic strength test (1RM) for biceps curl (1RMBC) and leg extension exercises (1RMLE), and functional performance tests (chair stand [CS], timed up and go [TUG] and maximal gait speed [MGS]) were performed before and after 12 weeks of training. RESULTS: MTBB increased significantly and similarly for all training groups (TRT 23.35%; ST 21.56%). MTVL increased significantly and similarly for all training groups (TRT 13.03%; ST 14.07%). 1RMBC increased significantly and similarly for all training groups (TRT 16.06%; ST 14.33%). 1RMLE increased significantly and similarly for all training groups (TRT 14.89%; ST 18.06%). MGS increased significantly and similarly for all groups (TRT 6.26%; ST 5.99%; CON 2.87%). CS decreased significantly and similarly for all training groups (TRT - 20.80%; ST - 15.73%). TUG decreased significantly and similarly for all training groups (TRT - 8.66%; ST - 9.16%). CONCLUSION: Suspension training (ST) promotes similar muscle mass, strength and functional performance improvements compared to TRT in older adults.

Lower Cardiovascular Stress during Resistance Training Performed with Inter-Repetition Rests in Elderly Coronary Patients.

Background and Objectives: Hemodynamic stress during resistance training is often a reason why this training method is not used in cardiac patients. A lifting protocol that imposes rests between repetitions (IRRT) may provide less hemodynamic stress compared to traditional resistance training (TT). The aim of this study was to verify differences between set configurations on hemodynamic stress responses in resistance training. Materials and Methods: We compared hemodynamic (heart rate (HR), systolic blood pressure (SBP), and rate pressure product (RPP)) responses assessed with the auscultatory method in elderly (age = 75.3 ± 7.3 years) coronary male patients who were participating in a cardiac rehabilitation program allocated to either TT or IRRT with the same load (kg) and total number of repetitions (24) in the bilateral leg extension exercise. Results: IRRT resulted in significant lower values than TT for RPP at repetitions 8 (p = 0.024; G = 0.329; 95% CI: 0.061, 0.598) and 16 (p = 0.014; G = 0.483; 95% CI: 0.112, 0.854). Conclusions: IRRT appears to be a viable method of reducing the hemodynamic response (i.e., RPP) to resistance training and, thus, may contribute to the safety of cardiac rehabilitation programs. Further studies with more cardiac patients and other measurement techniques should be conducted to confirm these important findings.

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.

Retrospective Study of Risk Factors and the Prevalence of Injuries in HIFT.

The aim of this study was to investigate the risk factors and the incidence of injuries in high-intensity functional training (HIFT) practitioners. A survey was administered to 213 HIFT practitioners. Participants reported the number of injuries, the location of the injuries, and training exposure during the preceding six months and answered questions regarding potential risk factors for injury. We found there were 7.1 injuries for every 1000 hours of training. In addition, we found that individuals with experience in the modality (>2 years) were 3.77 times more likely to be affected by injury when compared with beginner individuals (<6 months) (CI95%=1.59-8.92; p=0.003). When the analysis was performed only for the competitive level, we found that practitioners competing at the national level were 5.69 times more likely to experience an injury than competitors who do not compete (CI95%=1.10-29.54; p=0.038). We also found that the injuries mainly affect the shoulder and lumbar regions. It was possible to conclude that subjects with a higher level of experience in the modality are more likely to be affected by injuries and that the shoulder and lumbar areas are most likely to be injured during HIFT.

Acute Hemodynamic Responses to Repetitions to Failure Using Different Resistance Exercises and Protocols in Normotensive Men: A crossover study.

The present crossover design study investigated acute hemodynamic responses to two sets of leg press (LP) and bench press (BeP) at 10 and 20 repetition maximum (RM) in ten normotensive young men. At the end of each set, an increase in systolic blood pressure (SBP), heart rate (HR), and rate pressure product (RPP) was observed (p < .01), with no differences between intensities, but SBP was greater during the LP exercise (p < .01). Lower resting values of diastolic blood pressure (DBP) were observed in the post-BeP exercise period (p < .05), suggesting that DBP post-exercise hypotension may be more evident after upper-limb exercise.

Non-Uniformity of Elbow Flexors Damage Induced by an Eccentric Protocol in Untrained Men.

Muscle structure disorganization is a consequence of intense eccentric contractions, with symptoms that characterize exercise-induced muscle damage (EIMD). To date, few studies have described EIMD parameters at different muscle sites. The aim of the present study was to analyse indirect markers of EIMD at two elbow flexors sites over three days. Eleven healthy untrained men were submitted to a session of three sets of 10 eccentric elbow flexion repetitions on an isokinetic dynamometer. The isometric peak torque (PT), muscle soreness, elbow flexors oedema, (normalized muscle thickness [MT]) and echo-intensity (EI) were measured. There was a significant decrease in PT immediately after (Post) and 10 min, 24 h, 48 h and 72 h after intervention compared to that at baseline (p < 0 .05). MT% increased after 72 h compared with that immediately, 10 min and 24 h after intervention (p < 0.05). No statistical changes were observed in muscle soreness and oedema between the two muscle sites. With respect to EI%, significant differences were observed for the 24 h, 48 h and 72 h measures compared with those of the Post, 10 min and 24 h measures for both muscle sites; at the distal site, EI% was significantly higher than at the proximal site for measures after 24 h (p < 0.05). The presence of differences in EI% 24 h after eccentric training on distal sites of elbow flexors indicates non-uniform EIMD in this region.

Intradialytic resistance training: an effective and easy-to-execute strategy / Treinamento resistido intradialítico: uma estratégia eficaz e de fácil execução

Abstract Chronic kidney disease (CKD) alters the morphology and function of skeletal muscles, thereby decreasing patient physical capacity (PC) and quality of life (QoL). Intradialytic resistance training (IRT) is a pragmatic tool used to attenuate these complications. However, IRT has not been strongly adopted in nephrology care centers. This study aimed to assess the efficacy and safety of a low-cost, easy-to-use IRT protocol. Methods: The study enrolled 43 patients (52.8 ± 13.85 years) on HD for five to 300 months followed from April 2014 to July 2017. The efficacy of IRT was assessed based on PC - derived from muscle strength (MS) and preferred walking speed (PWS) - and QoL. The occurrence of adverse events was used as a measure of safety. The IRT protocol consisted of exercises of moderate to high intensity for the main muscle groups performed three times a week. Results: The mean follow-up time was 9.3 ± 3.24 months, for a total of 4,374 sessions of IRT. Compliance to the protocol was 96.5 ± 2.90%, and patients presented significant improvements in MS (from 27.3 ± 11.58 Kgf to 34.8 ± 10.77 Kgf) and PWS (from 0.99 ± 0.29 m/s to 1.26 ± 0.22 m/s). Physical and emotional components of QoL also increased significantly. Conclusion: IRT led to significant increases in PC and higher scores in all domains of QoL. Important adverse events were not observed during intradialytic resistance training.

Resumo A doença renal crônica (DRC) promove alterações morfofuncionais dos músculos esqueléticos, gerando redução da capacidade físico-funcional (CF) e pior qualidade de vida (QV). O treinamento resistido intradialítico (TRI) é considerado uma ação pragmática para atenuar tais complicações. Contudo, nota-se baixa inserção do TRI nos centros de tratamento em nefrologia. O objetivo deste estudo foi avaliar a eficácia e a segurança de uma proposta metodológica de TRI de fácil execução e de baixo custo. Métodos: 43 pacientes (52,8±13,85 anos), com tempo em HD entre cinco e 300 meses, foram acompanhados entre abril de 2014 e julho de 2017. A eficácia do TRI foi mensurada pela CF, avaliada pela força muscular (FM) e pela velocidade de caminhada usual (VCU) e pela QV. Como critério de segurança adotou-se a ocorrência de intercorrências clínicas. O protocolo de TRI consistiu em exercícios de moderada a alta intensidade para os principais grupos musculares, realizados três vezes por semana. Resultados: o tempo médio de acompanhamento foi de 9,3 ± 3,24 meses, totalizando 4.374 sessões de TRI. A aderência ao protocolo foi de 96,5 ± 2,90, e os pacientes apresentaram melhora significativa da FM (de 27,3±11,58 Kgf para 34,8±10,77 Kgf) e da VCU (de 0,99 ± 0,29 m/s para 1,26 ± 0,22 m/s). Quanto à QV, tanto os domínios do componente físico quanto do emocional aumentaram significativamente. Conclusão: o TRI promoveu aumento significativo da CF e melhora de todos os domínios da QV, e não foram observadas intercorrências importantes com a realização dos exercícios intradialíticos.

Humeral stress fracture in a female CrossFit athlete: a case report.

BACKGROUND: Humeral stress fractures are rare injuries usually related to sports practice and joint overload without a direct trauma. A proximal humeral stress fracture has never been reported in a CrossFit athlete. CASE PRESENTATION: We report a stress fracture in the humerus of a 22-year-old woman after intense CrossFit training. Patient's previous medical history included amenorrhea and reduced Vitamin D levels. The patient was treated conservatively and resumed CrossFit training after she was advised not to until follow up imaging. CONCLUSIONS: We present the MRI features of the case and emphasize the difficulties in diagnosis due to multiple possible causes of shoulder pain in a CrossFit athlete and by negative findings on early radiographs. Hormonal variations, Vitamin D insufficiency and the patient's attitude towards exercise were important factors that contributed for the stress injury after weight-lifting in CrossFit.

Postexercise Hypotension and Heart Rate Variability Responses Subsequent to Traditional, Paired Set, and Superset Resistance Training Methods.

Paz, GA, Iglesias-Soler, E, Willardson, JM, Maia, MdF, and Miranda, H. Postexercise hypotension and heart rate variability responses subsequent to traditional, paired set, and superset resistance training methods. J Strength Cond Res 33(9): 2433-2442, 2019-The purpose of this study was to compare training volume, postexercise hypotension (PEH), and heart rate variability (HRV) responses to different strength training methods. Thirteen trained men volunteered for this study. Three training methods were completed in a randomized design, which included: Traditional Set (TS)-3 successive sets for the lying bench press (LBP), lat pulldown (LPD), incline 45° bench press (BP45), seated close-grip row (SCR), triceps extension (TE), and biceps curl (BC), with a 90-second rest interval between sets and exercises; Paired Set (PS)-3 paired sets for the LBP-LPD, BP45-SCR, and TE-BC, with a 90-second rest interval between sets and exercises; and superset (SS)-3 supersets for the LBP-LPD, BP45-SCR, and TE-BC. During the SS session, no rest was permitted between PSs, followed by 180 seconds of rest after each SS. Ten repetition-maximum (RM) loads were adopted for all exercises. Blood pressure (BP) and HRV were measured at baseline, immediately aftersession, and at 10-minute intervals until 60 minutes after session. Significantly greater training volume was noted under the SS method (8,608.6 ± 2,062.2 kg) vs. the TS method (7,527.5 ± 2,365.1 kg), respectively. Significantly greater training volume was also observed under the PS method (8,262.3 ± 2,491.2 kg) vs. the TS method (p ≤ 0.05). No main effects for HRV and PEH were noted between protocols (p > 0.05). However, similar PEH response intraprotocols were observed for the TS, PS, and SS methods (p ≤ 0.05). Considering the duration of the PEH intraprotocol, large effect sizes were noted for the SS and PS methods vs. the TS method in diastolic and mean BP. Therefore, both the PS and SS methods may be an alternative to the TS method to achieve greater total repetitions and training volume with a tendency toward a longer PEH response.

Intradialytic resistance training: an effective and easy-to-execute strategy.

Chronic kidney disease (CKD) alters the morphology and function of skeletal muscles, thereby decreasing patient physical capacity (PC) and quality of life (QoL). Intradialytic resistance training (IRT) is a pragmatic tool used to attenuate these complications. However, IRT has not been strongly adopted in nephrology care centers. This study aimed to assess the efficacy and safety of a low-cost, easy-to-use IRT protocol. METHODS: The study enrolled 43 patients (52.8 ± 13.85 years) on HD for five to 300 months followed from April 2014 to July 2017. The efficacy of IRT was assessed based on PC - derived from muscle strength (MS) and preferred walking speed (PWS) - and QoL. The occurrence of adverse events was used as a measure of safety. The IRT protocol consisted of exercises of moderate to high intensity for the main muscle groups performed three times a week. RESULTS: The mean follow-up time was 9.3 ± 3.24 months, for a total of 4,374 sessions of IRT. Compliance to the protocol was 96.5 ± 2.90%, and patients presented significant improvements in MS (from 27.3 ± 11.58 Kgf to 34.8 ± 10.77 Kgf) and PWS (from 0.99 ± 0.29 m/s to 1.26 ± 0.22 m/s). Physical and emotional components of QoL also increased significantly. CONCLUSION: IRT led to significant increases in PC and higher scores in all domains of QoL. Important adverse events were not observed during intradialytic resistance training.

Intermittent resistance exercise and obesity, considered separately or combined, impair spermatic parameters in adult male Wistar rats.

Obesity and absence of physical exercise are global problems that affect concentration and sperm quality in the male reproductive system. The purpose of this study was to examine the effect of obesity and resistance training, considered separately or in association, on testicular function and reproductive capacity. Twenty pubertal male Wistar rats were distributed into four groups: control (C) and exercise (E) groups that received standard rat chow; and obese (O) and obese with exercise (OE) groups that received a high-fat diet. All the groups received filtered water during the experimental conditions. Groups E and OE were submitted to 8 weeks of high-intensity intermittent training. Afterwards, testes were collected for sperm count, spermatogenic kinetics, histopathology, morphometry and immunodetection of androgen receptors (AR). The vas deferens was collected for sperm morphology. The results showed that obesity increased body weight, naso-anal length, liver and epididymal fat weight, abnormal spermatozoa and immunodetectable AR. Intermittent exercise decreased daily sperm production (DSP), sperm count and normal spermatozoa, whereas the number of tubules with immunodetectable AR increased. The combination of obesity and intermittent training led to reduced sperm count and DSP, although abnormal spermatozoa and the number of tubules with immunodetectable AR increased. Thus, in conclusion, both obesity and resistance training impaired testicular function during puberty in rats; and this type of exercise has also been shown to be detrimental to testicular physiology.

Protective effects of photobiomodulation against resistance exercise-induced muscle damage and inflammation in rats.

We investigated whether low-level laser therapy (LLLT) prior to or post resistance exercise could attenuate muscle damage and inflammation. Female Wistar rats were assigned to non-LLLT or LLLT groups. An 830-nm DMC Laser Photon III was used to irradiate their hind legs with 2J, 4J, and 8J doses. Irradiations were performed prior to or post (4J) resistance exercise bouts. Resistance exercise consisted of four maximum load climbs. The load work during a resistance exercise bout was similar between Control (non-LLLT, 225 ± 10 g), 2J (215 ± 8 g), 4J (210 ± 9 g), and 8J (226 ± 9 g) groups. Prior LLLT did not induce climbing performance improvement, but exposure to 4J irradiation resulted in lower blood lactate levels post-exercise. The 4J dose decreased creatine kinase and lactic dehydrogenase levels post-exercise regardless of the time of application. Moreover, 4-J irradiation exposure significantly attenuated tumor necrosis factor alpha, interleukin-6, interleukin-1ß, cytokine-induced neutrophil chemoattractant-1, and monocyte chemoattractant protein-1. There was minor macrophage muscle infiltration in 4J-exposed rats. These data indicate that LLLT prior to or post resistance exercise can reduce muscle damage and inflammation, resulting in muscle recovery improvement. We attempted to determine an ideal LLLT dose for suitable results, wherein 4J irradiation exposure showed a significant protective role.

Strength training in children and adolescents: benefits, risks and recommendations / Entrenamiento de la fuerza en niños y adolescentes: beneficios, riesgos y recomendaciones

In the last decade, there has been a notable increase in the implementation of strength training programs in sports for children and adolescents. This review of strength training includes potential health benefits, fitness, risks and recommendations for the healthy, overweight, obese, or sedentary population in children 7-19 years of age. The general guidelines include supervision, planning and proper learning of the technique. Scientific evidence and clinical experience of strength training in children and adolescents as part of a training program demonstrate that it is useful, effective and safe if properly prescribed and supervised, with potential health benefits on a physical, social and psychological level

En la última década, se ha observado un notable incremento de la implementación de programas de entrenamiento de la fuerza en la práctica deportiva en niños y adolescentes. En esta revisión del entrenamiento de la fuerza, se incluyen los potenciales beneficios en la salud, en el acondicionamiento físico, los riesgos y recomendaciones para la población sana, con sobrepeso, obesidad o sedentaria en niños de 7 a 19 años. Las pautas generales incluyen la supervisión, la planificación y el correcto aprendizaje de la técnica. La evidencia científica y la experiencia clínica del entrenamiento de la fuerza en niños y adolescentes, como parte de un programa de entrenamiento, demuestran que es útil, eficaz y seguro si está prescrito y supervisado adecuadamente, con beneficios potenciales para la salud a nivel físico, psicológico y social.

Blood flow restriction attenuates eccentric exercise-induced muscle damage without perceptual and cardiovascular overload.

The aim of this study was to evaluate the acute effects of high-intensity eccentric exercise (HI-ECC) combined with blood flow restriction (BFR) on muscle damage markers, and perceptual and cardiovascular responses. Nine healthy men (26 ± 1 years, BMI 24 ± 1 kg m- ²) underwent unilateral elbow extension in two conditions: without (HI-ECC) and with BFR (HI-ECC+BFR). The HI-ECC protocol corresponded to three sets of 10 repetitions with 130% of maximal strength (1RM). The ratings of perceived exertion (RPE) and pain (RPP) were measured after each set. Muscle damage was evaluated by range of motion (ROM), upper arm circumference (CIR) and muscle soreness using a visual analogue scale at different moments (pre-exercise, immediately after, 24 and 48 h postexercise). Systolic (SBP), diastolic (DBP), mean blood pressure (MBP) and heart rate (HR) were measured before exercise and after each set. RPP was higher in HI-ECC+BFR than in HI-ECC after each set. Range of motion decreased postexercise in both conditions; however, in HI-ECC+BFR group, it returned to pre-exercise condition earlier (post-24 h) than HI-ECC (post-48 h). CIR increased only in HI-ECC, while no difference was observed in HI-ECC+BFR condition. Regarding cardiovascular responses, MBP and SBP did not change at any moment. HR showed similar increases in both conditions during exercise while DBP decreased only in HI-ECC condition. Thus, BFR attenuated HI-ECC-induced muscle damage and there was no increase in cardiovascular responses.

Texture analysis of ultrasound images is a sensitive method to follow-up muscle damage induced by eccentric exercise.

The grey level of co-occurrence matrix (GLCM) is a texture analysis approach accounting for spatial distribution of the pixels from an image and can be a promising method for exercise-induced muscle damage (EIMD) studies. We followed up the time changes of two GLCM texture parameters and echo intensity (EI) on ultrasound images after eccentric contractions. Thirteen untrained women performed two sets of ten elbow flexions eccentric contractions. Ultrasound images were acquired at baseline and 24 h, 48 h, 72 h and 96 h after exercise. Two GLCM texture parameters were calculated for the brachialis muscle: contrast (CON) and correlation (COR). Peak torque, EI, muscle thickness (MT) and soreness were measured. The peak torque and soreness decreased immediately after the intervention in comparison with all the measures. MT increased immediately after the intervention remaining for 72 h (P<0·05). Significant increases (P<0·05) were observed for COR (48, 72 and 96 h) and EI only at 72 and 96 h. The increasing COR represents high similarity between grey levels, which could be observed on US images after few days on eccentric training for elbow flexors.