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Skin temperature responses have been advocated to indicate exercise-induced muscle soreness and recovery status. While the evidence is contradictory, we hypothesize that the presence of muscle damage and the time window of measurement are confounding factors in the skin temperature response. The objective was to determine whether skin temperature is influenced by different workloads and the time course of temperature measurements over the following 24 h. 24 trained male military were assigned to one of three groups: GC group (n = 8) serving as control not performing exercises, GE group (n = 8) performing a simulated military combat protocol in an exercise track with different obstacles but designed not to elicit muscle damage, and the GEMD group (n = 8) performing the simulated military combat protocol plus 5 sets of 20 drop jumps, with 10-sec between repetitions and with 2-min of rest between sets aiming to induce muscle damage. Skin temperature was measured using infrared thermography before exercise (Pre) and 4 (Post4h), 8 (Post8h) and 24h (Post24h) post-exercise. Perception of pain (DOMS) was evaluated Pre, Post24h, and Post48h, and countermovement jump height was evaluated at Pre and Post24h. DOMS did not differ between groups in the Pre and Post24h measures but GEMD presented higher DOMS than the other groups at Post48h (p < 0.001 and large effect size). Jump height did not differ for GEMD and GC, and GE presented higher jump height at Post24h than GC (p = 0.02 and large effect size). Skin temperature responses of GEMD and GG were similar in all measurement moments (p > 0.22), and GE presented higher skin temperature than the GC and the GEMD groups at Post24h (p < 0.01 and large effect sizes). In conclusion, although physical exercise elicits higher skin temperature that lasts up to 24 h following the efforts, muscle soreness depresses this response.

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PURPOSE: Delayed-onset muscle soreness (DOMS) describes an entity characterized by ultrastructural muscle damage. Hesperidin methyl chalcone (HMC) is a synthetic flavonoid presenting analgesic, anti-inflammatory, and antioxidant properties. We evaluated the effects of HMC upon DOMS. METHOD: In a preventive paradigm, 31 sedentary young men were submitted to a randomized, double-blinded parallel trial and received HMC 500 mg or one placebo capsule × 3 days before an intense dynamic exercise protocol (concentric/eccentric actions) applied for lower limbs for inducing muscle damage. Assessments were conducted at baseline, and 24 and 48 h after, comprising physical performance, and post-muscle soreness and damage, inflammation, recovery of muscle strength, and postural balance associated with DOMS. HMC safety was also evaluated. Thirty participants completed the study. RESULTS: HMC improved the performance of participants during exercise (40.3 vs 51.3 repetitions to failure, p = 0.0187) and inhibited CPK levels (90.5 vs 57.9 U/L, p = 0.0391) and muscle soreness during passive quadriceps palpation (2.6 vs 1.4 VAS cm, p = 0.0439), but not during active actions, nor did it inhibit IL-1ß or IL-10 levels. HMC improved muscle strength recovery, and satisfactorily refined postural balance, without inducing injury to kidneys or liver. CONCLUSIONS: Preemptive HMC supplementation may be beneficial for boosting physical performance and for the amelioration of clinical parameters related to DOMS, including pain on muscle palpation, increased blood CPK levels, and muscle strength and proprioceptive deficits, without causing adverse effects. These data advance the understanding of the benefits provided by HMC for DOMS treatment, which supports its usefulness for such purpose.

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Cluster sets (CS) are effective in maintaining performance and reducing perceived effort compared to traditional sets (TRD). However, little is known about these effects on adolescent athletes. The purpose of this study was to compare the effect of CS on the performance of mechanical and perceptual variables in young athletes. Eleven subjects [4 boys (age = 15.5 ± 0.8 years; body mass = 54.3 ± 7.0 kg; body height = 1.67 ± 0.04 m; Back Squat 1RM/body mass: 1.62 ± 0.19 kg; years from peak height velocity [PHV]: 0.94 ± 0.50) and 7 girls (age = 17.2 ± 1.4 years; body mass = 54.7 ± 6.3 kg; body height = 1.63 ± 0.08 m; Back Squat 1RM/body mass: 1.22 ± 0.16 kg; years from PHV: 3.33 ± 1.00)] participated in a randomized crossover design with one traditional (TRD: 3 × 8, no intra-set and 225 s interest rest) and two clusters (CS1: 3 × 2 × 4, one 30 s intra-set and 180 s inter-set rest; and CS2: 3 × 4 × 2, three 30 s intra-set and 90 s inter-set rest) protocols. The subjects were assessed for a Back Squat 1RM for the first meet, then performed the three protocols on three different days, with at least 48 h between them. During experimental sessions, a back squat exercise was performed, and mean propulsive velocity (MPV), power (MPP), and force (MPF) were collected to analyze performance between protocols, together with measures of countermovement jump (CMJ) and perceptual responses through Rating of Perceived Exertion for each set (RPE-Set) and the overall session (S-RPE), and Muscle Soreness (DOMS). The results showed that velocity and power decline (MVD and MPD) were favorable for CS2 (MVD: -5.61 ± 14.84%; MPD: -5.63 ± 14.91%) against TRD (MVD: -21.10 ± 11.88%; MPD: -20.98 ± 11.85%) (p < 0.01) and CS1 (MVD: -21.44 ± 12.13%; MPD: -21.50 ± 12.20%) (p < 0.05). For RPE-Set, the scores were smaller for CS2 (RPE8: 3.23 ± 0.61; RPE16: 4.32 ± 1.42; RPE24: 4.46 ± 1.51) compared to TRD (RPE8: 4.73 ± 1.33; RPE16: 5.46 ± 1.62; RPE24: 6.23 ± 1.97) (p = 0.008), as well as for Session RPE (CS2: 4.32 ± 1.59; TRD: 5.68 ± 1.75) (p = 0.015). There were no changes for jump height (CMJ: p = 0.985), and the difference between time points in CMJ (ΔCMJ: p = 0.213) and muscle soreness (DOMS: p = 0.437) were identified. Our findings suggest that using CS with a greater number of intra-set rests is more efficient even with the total rest interval equalized, presenting lower decreases in mechanical performance and lower perceptual effort responses.

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The "zero point" method allows for lower intensities for an exercise session without impairing the total training volume. This study aimed to compare the effects of the "zero point" versus the traditional method on muscle responses and muscle damage in trained men. Fifteen experienced men (age: 27.7 ± 6.4 years; body mass: 78.4 ± 11.4 kg; height: 174.8 ± 4.9 cm; experience: 5.86 ± 4.7 years; relative bench press strength: 1.38 ± 0.17 kg·kg-1) were subjected to two exercise protocols in a randomized order and separated by a week. The traditional and "zero point" methods were applied in the bench press, with loads of 70% and 50% of one repetition maximum (1RM), respectively, for 10 sets until concentric failure, with 3-min intervals between sets. The zero point method displayed a higher number of repetitions and time under tension than the traditional method, with no difference in the total training volume, echo intensity, algometry, lactate, and myoglobin. For the muscle thickness, no differences between the groups were presented, except for the deltoid muscle thickness, in which a higher post-training volume was observed compared to traditional training. The "zero point" method increases the demand on the deltoid muscles in the bench press exercise, but not on the pectoralis and triceps brachii.

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The effectiveness of electrical stimulation (ES) in preventing or treating delayed-onset muscle soreness (DOMS) and its effects on muscle recovery is unclear. The systematic review investigated the benefits or harms of ES on DOMS and muscle recovery. Databases (PubMed, Medline, CENTRAL, EMBASE, CINAHL, PsycINFO, PEDro, LILACS, SPORTDiscus) were searched up to March, 31st 2021 for randomized controlled trials (RCTs) of athletes or untrained adults with DOMS treated with ES and compared to placebo/sham (simulation or without ES), or control (no intervention). Data were pooled in a meta-analysis. Risk of bias (Cochrane Collaboration tool) and quality of evidence (GRADE) were analyzed. Fourteen trials (n=435) were included in this review and 12 trials (n=389) were pooled in a meta-analysis. Evidence of very low to low quality indicates that ES does not prevent or treat DOMS as well as ES does not help to promote muscle recovery immediately, 24, 48, 72, 96 hours after the intervention. Only one study monitored adverse events. There are no recommendations that support the use of ES in DOMS and muscle recovery. PERSPECTIVES: No recommendations support the use of electrical stimulation in delayed-onset muscle soreness and muscle recovery in athletes and untrained adults. This means that electrical stimulation is not fruitful for this population according those protocols used. Therefore, unlikely that further randomized controlled trials with the same approach will yield promising results.

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The effect of caffeine on mitigating exercise-induced muscle damage (EIMD) is still poorly understood, but it was hypothesized that caffeine could contribute to decreasing delayed onset muscle soreness, attenuating temporary loss of strength, and reducing circulating levels of blood markers of muscle damage. However, evidence is not conclusive and beneficial effects of caffeine ingestion on EIMD are not always observed. Factors, such as the type of exercise that induces muscle damage, supplementation protocol, and type of marker analyzed contribute to the differences between the studies. To expand knowledge on the role of caffeine supplementation in EIMD, this systematic review aimed to investigate the effect of caffeine supplementation on different markers of muscle damage. Fourteen studies were included, evaluating the effect of caffeine on indirect muscle damage markers, including blood markers (nine studies), pain perception (six studies), and MVC maximal voluntary contraction force (four studies). It was observed in four studies that repeated administration of caffeine between 24 and 72 h after muscle damage can attenuate the perception of pain in magnitudes ranging from 3.9% to 26%. The use of a single dose of caffeine pre-exercise (five studies) or post-exercise (one study) did not alter the circulating blood levels of creatine kinase (CK). Caffeine supplementation appears to attenuate pain perception, but this does not appear to be related to an attenuation of EIMD, per se. Furthermore, the effect of caffeine supplementation after muscle damage on strength recovery remains inconclusive due to the low number of studies found (four studies) and controversial results for both dynamic and isometric strength tests.

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BACKGROUND: The effects of ischemic preconditioning (IPC) versus a deceptive sham protocol on indirect markers of exercise-induced muscle damage (EIMD) after the application of individualized occlusion pressure were examined. The goal of using a sham protocol is to control for the potential effect of placebo. HYPOTHESIS: IPC would surpass the sham protocol in protecting against EIMD. STUDY DESIGN: A randomized, double-blinded, clinical trial. LEVEL OF EVIDENCE: Level 1. METHODS: Thirty healthy young men were randomly assigned to an eccentric exercise for the knee extensor muscles preceded by IPC (4 × 5 minutes of individualized total occlusion pressure) or sham protocol (4 × 5 minutes using 20 mm Hg). Maximal voluntary isometric torque (MVIT), rate of torque development, muscle soreness, pressure pain threshold, knee range of motion, thigh girth, and creatine kinase (CK) activity were assessed before IPC or sham protocol and up to 72 hours after the eccentric EIMD. Affective valence and perceived exertion were also evaluated. RESULTS: MVIT decreased 17.1% in the IPC and 18.1% in the sham groups, with no differences between groups. Differences from baseline were observed in the sham group for muscle soreness at 48 hours (P < 0.001) and 72 hours (P = 0.02), and for CK activity at 72 hours (P = 0.04). Muscle soreness was reduced in the IPC group at 48 hours compared with the sham group (∆ = 15.8 mm; P = 0.008) but without achieving the minimal clinically important difference. IPC induced a smaller perceived exertion than the sham protocol (∆ = 1.1 a.u.; P = 0.02). The remaining outcomes were not statistically different in both groups. CONCLUSION: IPC does not surpass the sham protocol to protect against mild EIMD of the knee extensors muscles. CLINICAL RELEVANCE: Although IPC is a noninvasive, low-cost, and easy-to-administer intervention, the IPC effects can, in part, be explained by the placebo effect. In addition, individualized IPC promotes attenuation in perceived exertion during eccentric exercise.

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Unaccustomed exercise involving eccentric contractions, high intensity, or long duration are recognized to induce delayed-onset muscle soreness (DOMS). Myocyte damage and inflammation in affected peripheral tissues contribute to sensitize muscle nociceptors leading to muscle pain. However, despite the essential role of the spinal cord in the regulation of pain, spinal cord neuroinflammatory mechanisms in intense swimming-induced DOMS remain to be investigated. We hypothesized that spinal cord neuroinflammation contributes to DOMS. C57BL/6 mice swam for 2 h to induce DOMS, and nociceptive spinal cord mechanisms were evaluated. DOMS triggered the activation of astrocytes and microglia in the spinal cord 24 h after exercise compared to the sham group. DOMS and DOMS-induced spinal cord nuclear factor κB (NFκB) activation were reduced by intrathecal treatments with glial inhibitors (fluorocitrate, α-aminoadipate, and minocycline) and NFκB inhibitor [pyrrolidine dithiocarbamate (PDTC)]. Moreover, DOMS was also reduced by intrathecal treatments targeting C-X3-C motif chemokine ligand 1 (CX3CL1), tumor necrosis factor (TNF)-α, and interleukin (IL)-1ß or with recombinant IL-10. In agreement, DOMS induced the mRNA and protein expressions of CX3CR1, TNF-α, IL-1ß, IL-10, c-Fos, and oxidative stress in the spinal cord. All these immune and cellular alterations triggered by DOMS were amenable by intrathecal treatments with glial and NFκB inhibitors. These results support a role for spinal cord glial cells, via NFκB, cytokines/chemokines, and oxidative stress, in DOMS. Thus, unveiling neuroinflammatory mechanisms by which unaccustomed exercise induces central sensitization and consequently DOMS.

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We investigated if the same isometric preconditioning protocol (IPP) attenuates the magnitude of muscle damage induced by different maximal eccentric exercise protocols in the elbow flexors. Sixty-four untrained men were assigned to either two experimental or two control groups. Participants in the experimental groups performed an IPP prior to either slow (60°·s-1 - ISO + ECC-S) or fast (180°·s-1 - ISO + ECC-F) maximal eccentric contractions (MaxECC). Subjects in the control groups performed slow (ECC-S) or fast (ECC-F) MaxECC without IPP. Maximal isokinetic concentric torque (MVC), muscle soreness (SOR), and muscle thickness (MT) were assessed before, immediately after, and 1-4 days following the MaxECC. Significant (p < 0.05) group vs. time interactions were found for MVC (F = 4,517), SOR (F = 6,318), and MT (F = 1,863). The ECC-S group presented faster (p < 0.05) recovery of MVC and MT and less (p < 0.05) SOR at 96 h post-MaxECC compared with ECC-F group. No significant differences in MVC and MT were found between ECC-S and ECC-F groups following MaxECC. The ISO + ECC-S group showed faster (p < 0.05) recovery of MVC and SOR compared to the ECC-S group. No significant differences were evident between ISO + ECC-S and ECC-S in any variable. The ISO + ECC-F group showed faster (p < 0.05) recovery of all assessed variables compared with the ECC-F group. MVC was greater (p < 0.05) at 48-72 h, and SOR was less (p < 0.05) at 48-96 h in the ISO + ECC-F compared to the ECC-F group. No significant differences were evident between ISO + ECC-S and ISO + ECC-F for any variable. These results show that the IPP accelerated recovery of MVC and SOR for the slow-eccentric exercise condition and attenuated strength loss and SOR in addition to faster recovery of all assessed variables for the fast-eccentric exercise condition. Therefore, the IPP can be used as a strategy to attenuate and accelerate recovery of muscle damage induced by different-velocity eccentric exercises, resulting in greater protection against muscle damage induced by faster velocity.

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The purpose of this study was to determine whether Far-Infrared Emitting Ceramic Materials worn as Bioceramic pants would improve neuromuscular performance, biochemical and perceptual markers in healthy individuals after maximal eccentric exercise. Twenty-two moderately active men were randomized into Bioceramic (n = 11) or Placebo (n = 11) groups. To induce muscle damage, three sets of 30 maximal isokinetic eccentric contractions of the quadriceps were performed at 60°·s-1. Participants wore the bioceramic or placebo pants for 2 hours immediately following the protocol, and then again for 2 hours prior to each subsequent testing session at 24, 48 and 72 hours post. Plasma creatine kinase and lactate dehydrogenase activity, delayed-onset muscle soreness, perceived recovery status, and maximal voluntary contraction were measured pre-exercise and 2, 24, 48, and 72 hours post-exercise. Eccentric exercise induced muscle damage as evident in significant increases in delayed-onset muscle soreness at 24 - 72 hours (p < 0.05) and creatine kinase between Pre to 2, 24, 48 and 72 hours (p < 0.05). Despite the increased delayed-onset muscle soreness and creatine kinase values, no effect of Bioceramic was evident (p > 0.05). Furthermore, decreases in maximal voluntary contraction between Pre and immediately, 2, 24, 48 and 72 hours post (p < 0.05) were reported. However, the standardized difference was moderate lower for lactate dehydrogenase at 24 h (ES = 0.50), but higher at 48 h (ES = -0.58) in the Bioceramic compared to the Placebo group. Despite inducing muscle damage, the daily use of Far-Infrared Emitting Ceramic Materials clothing over 72 hours did not facilitate recovery after maximal eccentric exercise.

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The aim was to investigate the effects of far infrared (FIR) ray emitting clothes on indirect markers of exercise-induced muscle damage and physical performance recovery after a plyometric bout applied to soccer players. Twenty-one male players (18.9±0.6 years; 70.8±5.01 kg; 178.3±0.06 cm) performed 100 drop-jumps. Six hours after the bout, athletes put on FIR clothes (FIR) (density of 225 g·m(-2), 88% far infrared rays emitting polyamide 66 Emana yarn (PA66) fibre, 12% Spandex, emissivity of 0.88 and power emitted of 341 W/m2µm at 37°C in the 5-20 µm wavelength range, patent WO 2009/077834 A2) (N = 10) or placebo clothes (PLA) (N = 11). Mid-thigh circumferences, creatine kinase (CK), and delayed-onset muscle soreness (DOMS) were assessed before, immediately after and 24, 48, and 72 h after the bout. Squat (SJ) and countermovement jump (CMJ) heights were measured before and at 24, 48, and 72 h after, while 1RM leg press (maximum strength) was measured before and at 72 h after the plyometrics. No differences between groups were found in mid-thigh circumferences, SJ, CMJ or 1RM. CK increased significantly 24 h after the plyometrics in comparison to before (p < 0.05) in both groups. PLA showed significant DOMS increases at 24, 48, and 72 h, while FIR showed significant increases at 24 and 48 h (p < 0.05). DOMS effect sizes were greater in FIR (moderate at 48 h, ES = 0.737 and large at 72 h, ES = 0.844), suggesting that FIR clothes may reduce perceived DOMS after an intense plyometric session performed by soccer players.

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OBJECTIVE: To identify effects of shortening and lengthening low-intensity resistance exercise together with aerobic exercise on physical fitness and muscular strength in senior adults. METHOD: Seventeen males (58-72yrs) and sixteen females (58-68yrs) participated in this study: seven male and six female as control subjects, ten male and ten female as exercise subjects: these subjects completed an 8-week training program (two times/week) consisting of 15 minutes of aerobike exercise at 50% of VO2max and six shortening-lengthening resistance exercises (3 exercises for upper body and 3 exercises for lower body). The subjects exercised resistance training (5 sec for shortening, 5 sec for lengthening) at 50% of one repetition maximum. Primary outcome measures included physical fitness tests (grip strength, sit-ups, sit-and-reach, 6 minutes of walking, single-leg balance test with open eyes), timed up-and-go test (UP&GO), and one repetition maximum of the same six exercises. This study examined joint angle of knee flexion and elbow flexion, visual analog scale, and muscular strength test to identify delayed onset muscle soreness. RESULTS: The resting blood pressures in both exercising groups were significantly decreased after 16 sessions of exercise intervention (p < 0.05). The training group significantly increased muscular strength and improved physical fitness, UP&GO, and one repetition maximum of 6 resistance exercises (p < 0.05). The combined exercise did not induce delayed onset muscle soreness. CONCLUSION: The present study showed that the combined shortening and lengthening resistance training with aerobic exercise in senior male and female adults was effective in decreasing blood pressure and increasing muscular strength and physical fitness.

OBJETIVO: Identificar os efeitos de encurtamento e alongamento através de exercício resistivo de baixa intensidade, juntamente com exercício aeróbico sobre a aptidão física e força muscular em idosos. MÉTODO: Dezessete homens (58-72 anos) e dezesseis mulheres (58-68 anos) participaram deste estudo: 7 homens e 6 mulheres como controles, 10 homens e 10 mulheres submetidos aos exercícios: um programa de treinamento bissemanal de 8 semanas, consistindo em dez minutos de aerobike a 50% do VO2max e seis exercícios de alongamento/encurtamento (três para membros superiores e três para membros inferiores). Cada exercido foi repetido quinze vezes (50% de Uma-Repetição-Máxima - 1RM) com 5 seg para encurtamento e 5 seg para alongamento). Foram medidos: força de preensão, sit-ups, sentar-e-alcançar, 6 minutos de caminhada, teste de equilíbrio de single-leg com os olhos abertos), teste up-and-go (UP & GO), 1RM dos mesmos seis exercícios, ângulo articular de flexão do joelho e flexão de cotovelo, escala analógica visual, e teste de força muscular para identificar dor muscular tardia. RESULTADOS: A pressão arterial em repouso do grupo exercício apresentou diminuição significativa após as 16 sessões de exercício. O grupo de treinamento aumentou significativamente a força muscular com melhoria da aptidão física, UP & GO, e uma repetição máxima de 6 exercícios de resistência. O exercício combinado não induziu dor muscular tardia. CONCLUSÃO: O presente estudo mostrou que o encurtamento/alongamento combinado com o exercício aeróbico em adultos idosos do sexo masculino e feminino foi eficaz para a diminuição da pressão arterial e aumento de força muscular e aptidão física.

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A recuperação pós-exercício é de extrema relevância dentro de todo programa de condicionamento físico, tanto para praticantes e atletas, como para técnicos e diversos profissionais ligados à área da saúde. Nesse sentido, o conhecimento a respeito da recuperação pós-exercício e dos vários métodos utilizados com intuito de acelerar o processo de recuperação (para suportar mais frequentes e/ou maiores cargas de treinamento com mais qualidade) torna-se essencial. Dessa forma, as intervenções utilizadas de forma profilática e/ou terapêutica com o intuito de amenizar os efeitos negativos das lesões musculares causadas pelo exercício físico e, assim, otimizar a recuperação são de grande interesse para pesquisadores, técnicos e atletas. Em vista disso, o objetivo da presente revisão de literatura é reunir informações que permitam descrever as respostas fisiológicas frente aos métodos de recuperação pós-exercícios, com a finalidade de melhorar tanto o processo de treinamento físico como o rendimento.

Post-exercise recovery is a key factor within every physical training program for athletes and non-athletes alike, as well as coaches and health professionals. Thus, knowledge on the post-exercise recovery process and the efficacy of the recovery modalities in enhancing between-training session (to increase training frequency and/or training loads qualitatively) is essential. Therefore, prophylactic or therapeutic interventions that might reduce the negative effects of exercise-induced muscle damage, thereby speeding recovery, are of great interest to researchers, coaches and athletes. As such, the purpose of this review was to describe the physiological responses to post-exercise recovery modalities currently used to aid athlete recovery during the training process, and consequently enhance performance.