Exercise-induced Muscle Damage Research Articles

Effects of Loaded Plyometric Exercise on Post-Activation Performance Enhancement of Countermovement Jump in Sedentary Men

ABSTRACT Purpose: Explosive performance is increased right after performing loaded resistance exercise, which is known as post-activation performance enhancement (PAPE). Method: We investigated the effects of a plyometric exercise (PLYO) consisting of five sets of six drop-jumps from a 52-cm platform with a load corresponding to 20% body mass on changes in countermovement jump (CMJ) height in sedentary young men. Eleven young nonresistance trained men (19.6 ± 1.8 y, 69 ± 9 kg, 1.76 ± 0.08 m) who showed more than 4% increase in CMJ height at 4 min after five back squats with five-repetition maximum load participated in the study. Their responses to the back squat exercise were examined before (baseline) and 15 minutes, 24 and 48 hours post-PLYO. Exercise-induced muscle damage markers (maximal voluntary contraction torque [MVC], and quadriceps muscle soreness) were assessed at baseline, 15 minutes, 24 and 48 hours following PLYO. Results: MVC torque decreased (p < .05) at 15 minutes post-PLYO (−15.1 ± 9.7%) but returned to the baseline at 24 hours post-PLYO. Muscle soreness developed (p < .05) at 48 hours (21.0 ± 20.3 mm) after PLYO, indicating minor muscle damage. CMJ height increased (p < .05) after the five squats at baseline (7.6 ± 3.8%) indicating PAPE, but no such increase was found at 15 minutes, 24 and 48 hours after PLYO. However, CMJ height before the squat exercise was greater (p < .05) at 24 (5.9 ± 7.0%) and 48 hours post-PLYO (9.1 ± 8.5%) than the baseline. Conclusions: These results showed that PAPE disappeared after PLYO that induced minor muscle damage, but CMJ height increased at 24–48 hours in the recovery from PLYO exhibiting a priming effect.

Preconditioning with whole-body or regional hyperthermia attenuates exercise-induced muscle damage in rodents.

Our aim was to investigate whether hyperthermia before exercise protects against exercise-induced skeletal muscle damage. Two hyperthermia protocols were evaluated. In the first, male ICR mice were exposed to 30 min of whole-body heat in an environmental chamber at an ambient temperature of 42 °C. Heat-exposed and non-heat-exposed mice subsequently completed 60 min of downhill running on a treadmill, 24 h after exposure. Heat exposure significantly increased HSP70 and HSP25 content in the soleus muscle compared to controls. Plasma creatine kinase, muscle beta-glucuronidase, and histochemical (hematoxylin and eosin stain) analysis demonstrated that muscle damage was lower in the heat-exposed mice than in the non-heat-exposed mice. In the second, the effect of regional heating of the legs, by microwave diathermy, on the prevention of exercise-induced muscle damage was evaluated in male Wistar rats. Microwave-treated and non-microwave-treated rats again completed the running protocol 24 h after exposure. Microwave diathermy increased the muscle temperature to 40 °C, significantly increased HSP70 and HSP25 content in the soleus muscle, and significantly attenuated exercise-induced muscle damage. Therefore, hyperthermia before exercise increases skeletal muscle HSPs and attenuates the risk of exercise-induced muscle injury.

Eccentric Exercise Causes Specific Adjustment in Pyruvate Oxidation by Mitochondria.

The impact of eccentric exercise on mitochondrial function has only been poorly investigated and remains unclear. This study aimed to identify the changes in skeletal muscle mitochondrial respiration, specifically triggered by a single bout of eccentric treadmill exercise. Male adult mice were randomly divided into eccentric (ECC; downhill running), concentric (CON; uphill running), and unexercised control groups ( n = 5/group). Running groups performed 18 bouts of 5 min at 20 cm·s -1 on an inclined treadmill (±15° to 20°). Mice were sacrificed 48 h after exercise for blood and quadriceps muscles collection. Deep proximal (red) and superficial distal (white) muscle portions were used for high-resolution respirometric measurements. Plasma creatine kinase activity was significantly higher in the ECC compared with CON group, reflecting exercise-induced muscle damage ( P < 0.01). The ECC exercise induced a significant decrease in oxidative phosphorylation capacity in both quadriceps femoris parts ( P = 0.032 in proximal portion, P = 0.010 in distal portion) in comparison with the CON group. This observation was only made for the nicotinamide adenine dinucleotide (NADH) pathway using pyruvate + malate as substrates. When expressed as a flux control ratio, indicating a change related to mitochondrial quality rather than quantity, this change seemed more prominent in distal compared with proximal portion of quadriceps muscle. No significant difference between groups was found for the NADH pathway with glutamate or glutamate + malate as substrates, for the succinate pathway or for fatty acid oxidation. Our data suggest that ECC exercise specifically affects pyruvate mitochondrial transport and/or oxidation 48 h after exercise, and this alteration mainly concerns the distal white muscle portion. This study provides new perspectives to improve our understanding of the mitochondrial adaptation associated with ECC exercise.

Intensified training in adolescent female athletes: a crossover study of Greek yogurt effects on indices of recovery.

ABSTRACTBackgroundDuring a period of intensified exercise (e.g. training/identification camps), often undertaken by competitive youth athletes, the maintenance of muscle function and peak performance can become challenging due to an accumulation of fatigue. The provision of post-exercise dairy protein in adults has been previously shown to accelerate recovery; however, its efficacy in youth athletes is currently unknown. Therefore, the purpose of this study was to examine the effects of increased dairy protein consumption with plain Greek yogurt (GY) on performance and recovery indices during an intensified soccer training camp in adolescent female soccer players.MethodsThirteen players (14.3 ± 1.3 years) participated in a randomized, double blinded, crossover design study where they received 3 servings/day of either GY (~115 kcal, 17 g protein, ~11.5 g carbohydrates) or an isoenergetic carbohydrate control (CHO, ~115 kcal, 0.04 g protein, ~28.6 g carbohydrates) during two 5-day soccer-specific training camps. Performance was assessed before and after each training camp. Fasted, morning, creatine kinase (CK), insulin-like growth factor-1 (IGF-1), C-reactive protein (CRP), interleukin 6 (IL6), interleukin 10 (IL10) and tumor necrosis factor-α (TNFα) were measured in plasma pre- and post-training.ResultsTraining led to decrements in counter-movement jump (p = 0.01), broad jump (p = 0.04) and aerobic capacity (p = 0.006), with no effect of GY. A significant increase in anti-inflammatory cytokine IL10 was observed from pre- to post-training in GY (+26% [p = 0.008]) but not in CHO (p = 0.89). CRP and CK increased (+65% [p = 0.005] and +119% [p ≤ 0.001], respectively), while IGF-1 decreased (−34% [p ≤ 0.001]) from pre- to post-training with no difference between conditions.ConclusionsThese results demonstrate that consumption of GY did not offer any added recovery benefit with respect to measures of performance and in the attenuation of exercise-induced muscle damage above that achieved with energy-matched carbohydrate in this group of young female soccer players. However, regular consumption of GY may assist with the acute anti-inflammatory response during periods of intensified training in adolescent athletes.

Polygenic mechanisms underpinning the response to exercise-induced muscle damage in humans: In vivo and in vitro evidence.

We investigated whether 20 candidate single nucleotide polymorphisms (SNPs) were associated with in vivo exercise-induced muscle damage (EIMD), and with an in vitro skeletal muscle stem cell wound healing assay. Sixty-five young, untrained Caucasian adults performed 120 maximal eccentric knee-extensions on an isokinetic dynamometer to induce EIMD. Maximal voluntary isometric/isokinetic knee-extensor torque, knee joint range of motion (ROM), muscle soreness, serum creatine kinase activity and interleukin-6 concentration were assessed before, directly after and 48 h after EIMD. Muscle stem cells were cultured from vastus lateralis biopsies from a separate cohort (n = 12), and markers of repair were measured in vitro. Participants were genotyped for all 20 SNPs using real-time PCR. Seven SNPs were associated with the response to EIMD, and these were used to calculate a total genotype score, which enabled participants to be segregated into three polygenic groups: 'preferential' (more 'protective' alleles), 'moderate', and 'non-preferential'. The non-preferential group was consistently weaker than the preferential group (1.93 ± 0.81 vs. 2.73 ± 0.59 N ∙ m/kg; P = 9.51 × 10-4 ) and demonstrated more muscle soreness (p = 0.011) and a larger decrease in knee joint ROM (p = 0.006) following EIMD. Two TTN-AS1 SNPs in linkage disequilibrium were associated with in vivo EIMD (rs3731749, p ≤ 0.005) and accelerated muscle stem cell migration into the artificial wound in vitro (rs1001238, p ≤ 0.006). Thus, we have identified a polygenic profile, linked with both muscle weakness and poorer recovery following EIMD. Moreover, we provide evidence for a novel TTN gene-cell-skeletal muscle mechanism that may help explain some of the interindividual variability in the response to EIMD.

The Importance of Branched-chain Amino Acids and Nitrate in Sports Performance and Health

Branched-chain amino acids (BCAA) and nitrate have become increasingly popular mainly for their potential effect on individuals' health and secondary as ergogenic aids. The purpose of this narrative review was to incorporate the current scientific evidence of BCAA and nitrate supplementation on athletic performance and health. The current recommendations of BCAA and nitrate supplementation are discussed, as well as possible health complications associated with its intake. Pubmed, Scopus, and Web of Science were searched for articles on the effects of BCAA and nitrate supplementation in humans. The positive effect of BCAAs supplementation on athletic performance does not appear to be fully established. BCAAs supplementation seems to be recommended for all athletes who exercise vigorously daily, as it enhances their recovery after causing exercise-induced muscle damage. BCAAs supplementation reduces the feeling of delayed muscle pain, which follows because of muscle damage. Limited scientific data suggest a potentially beneficial effect of BCAAs on reducing central fatigue. Several clinical conditions could benefit from BCAAs' consumption. However, there are no reliable markers to evaluate or quantify their requirements. There are no exact consumption protocols and absolute recommendations, mainly because BCAAs are also obtained through the consumption of animal protein. Dietary nitrates lower blood pressure, reduce the cost of exercise oxygen, and, at least sometimes, enhance exercise capacity. Taking supplements for 2-6 days (or up to 15 days) can increase athletic performance during high-intensity exercise. The duration of continuous maximum exercise for which nitrates appear to be ergogenic is between 5-30 min. There is limited evidence that nitrates are beneficial in prolonged exercise performance (40 min), at least when administered short term. Supplementation of approximately 5-9 mmol of nitrate/day for 1-15 days may have beneficial effects on normal exercise responses, although the exact dose-response relationship has not yet been established. Five to 9 mmol of nitrates can be easily consumed in the normal diet and there is currently no evidence to adequately document that taking additional nitrates produces greater benefits. The effectiveness of acute nitrate supplementation is likely to depend on many factors, such as sex, health, hypoxia, diet, and level of fitness/training experience of the subjects. Nitrate needs are most likely met by ingesting approximately 250-500 g of leafy and root vegetables per day; however, dietary supplements might represent a more convenient and accurate way of covering an athlete's nitrate needs.

Preventive effects of Spirulina platensis on exercise-induced muscle damage, oxidative stress and inflammation in taekwondo athletes: a randomized cross-over trial

Abstract Background: Spirulina is an interesting nutritional supplement that has attracted a lot of attention. The aim of the present study was to examine the effect of spirulina supplementation on oxidative stress, inflammatory factors and plasma markers of exercise-induced muscle damage in male taekwondo athletes. Results: A total of 18 trained taekwondo male athletes took part in a double-blind, placebo-controlled crossover study. Each subject received either spirulina (8 g/day) or placebo for 3 weeks. The study had two periods separated by a 14-day washout. Blood samples were taken after finishing a training checklist program (4 times in total). There were no significant carryover effects; therefore, the two-week washout period was adequate. Compared to the placebo, a dose of 8 g / d of spirulina supplement over 21 days resulted in a significant decrease in plasma levels of lactate dehydrogenase (LDH), creatine kinase (CK) and interleukin 6 (IL6) and a significant increase in plasma levels of total antioxidant capacity (TAC), superoxide dismutase (SOD) and glutathione peroxidase (GPX) (p&lt;0.05). There was not any statistically significant change in the plasma malondialdehyde (MDA) (p&gt;0.05). Conclusion: Due to the improvement of antioxidant and anti-inflammatory conditions as well as an appropriate protein content, spirulina supplementation can produce a preventive effect on exercise-induced muscle damage in taekwondo athletes. Trial registration: Iranian Registry of Clinical Trials, IRCT20121110011421N4. Registered 12 July 2021 - Retrospectively registered, https://irct.ir/trial/11692.

The combined effects of exercise-induced muscle damage and heat stress on acute kidney stress and heat strain during subsequent endurance exercise.

The purpose of the study was to investigate the combined effect of downhill running and heat stress on muscle damage, as well as on heat strain and kidney stress during subsequent running in the heat. In a randomized cross-over study, ten non-heat-acclimated, physically active males completed downhill running in temperate (EIMD in Temp) and hot (EIMD in Hot) conditions followed by an exercise-heat stress (HS) test after 3-h seated rest. Blood and urine samples were collected immediately pre- and post-EIMD and HS, and 24h post-EIMD (post-24h). Core temperature and thermal sensation were measured to evaluate heat strain. Serum creatine kinase (CK), maximal voluntary isometric contraction of the quadriceps (MVC) and perceived muscle soreness were measured to evaluate muscle damage. Urinary neutrophil gelatinase-associated lipocalin (NGAL) and kidney injury molecule-1 (KIM-1) levels were measured to indicate acute kidney stress. CK, MVC and perceived soreness were not different between conditions at any timepoints. In the EIMD in Hot condition, urinary NGAL was significantly elevated from pre- to post-HS (pre-HS: 6.56 {1.53-12.24}ng/min, post-HS: 13.72 {7.67-21.46}ng/min, p = 0.034). Such elevation of NGAL or KIM-1 was not found in the EIMD in Temp condition. As compared with downhill running in a temperate environment, downhill running in a hot environment does not appear to aggravate muscle damage. However, elevated NGAL levels following EIMD in a hot environment suggest such exercise may increase risk of mild acute kidney injury during subsequent endurance exercise in the heat.

Effect of Velocity-Based Heavy Resistance Exercise on Exercise-Induced Muscle Damage

&lt;p&gt;目的：探討動作速度流失率達20%即停止的速度依循高強度阻力運動對運動後之血液肌酸激酶 (CK) 活性、肌肉痠痛之視覺類比量表 (VAS) 分數、關節活動角度 (ROM) 與推動槓鈴速度為每秒1公尺的負荷重量 (V1 load) 之動作速度等運動誘發肌肉損傷 (EIMD) 指標之影響。方法：十二位大專男性柔道運動員採交叉、平衡次序的方式，執行3組、負荷為85% 1-RM、反覆至動作速度流失率達20%即停止 (VL20) 與反覆至力竭 (RF) 的臥推與深蹲運動；於運動前、運動後立即、運動後24與48小時量測各項EIMD指標，並紀錄運動執行情形。所測得數據以相依樣本t檢定及重複量數二因子變異數分析比較各項數值之差異。結果：VL20試驗執行第3組深蹲之動作速度流失率顯著低於RF試驗，並在運動後24小時之CK活性即與運動前無顯著差異，而RF試驗在運動後24小時之CK活性仍顯著高於運動後48小時；且VL20試驗在運動後各時間點的VAS分數皆顯著低於RF試驗、運動後24小時臥推V1 load之速度顯著高於RF試驗。結論：執行3組、85% 1-RM、控制動作速度流失率為20%的高強度阻力運動時，在執行深蹲後段會有較小的動作速度流失率，且在運動後立即至運動後48小時都有較低的痠痛感覺；即此方式能降低運動誘發肌肉損傷與加速運動後的恢復。&lt;/p&gt; &lt;p&gt;&amp;nbsp;&lt;/p&gt;&lt;p&gt;Purpose: To investigate the effect of velocity based heavy resistance exercise with 20% velocity loss on plasma creatine kinase (CK) activity, visual analog scale (VAS) of muscle soreness, range of motion (ROM), and against velocity 1 m/s load (V1 load) which commonly used as the indicators of exercise-induced muscle damage (EIMD). Methods: Twelve male collegiate judokas were recruited into the study. Participants performed 3 sets of heavy resistance exercise of bench press and squat at 85% of 1-RM, with the repetitions to 20% velocity loss (VL20) or failure (RF) in a counterbalanced crossover manner. The variables of EIMD and exercise load were measured at the time points of before exercise, immediately after exercise, 24 and 48 hr after exercise. Paired t-test and two-way ANOVA with repeated measurement were used to analyze the variables. Results: The velocity loss for the third set of squats in VL20 trail was significantly lower than in RF trail. The CK activity at 24 hours after exercise in VL20 trail was no significant difference as compared to before exercise. However, the CK activity at 24-hr after exercise in RF trail was significantly higher than 48-hr after exercise. The VAS scores at each time point after exercise in VL20 trail were significantly lower than in RF trail. Moreover, the velocity against the V1 load in bench press at 24-hr after exercise in VL20 trail was significantly higher than in RF trail. Conclusion: Controlling the repetition to 20% velocity loss during heavy resistance exercise for 3 sets of 85% of 1-RM enabled lower velocity loss in squat and lower muscle pain after exercise. It can minimize exercise-induced muscle damage and speed up recovery following resistance training.&lt;/p&gt; &lt;p&gt;&amp;nbsp;&lt;/p&gt;

Effects of compression garment on muscular efficacy, proprioception, and recovery after exercise-induced muscle fatigue onset for people who exercise regularly.

Fatigue is a major cause of exercise-induced muscle damage (EIMD). Compression garments (CGs) can aid post-exercise recovery, therefore, this study explored the effects of CGs on muscular efficacy, proprioception, and recovery after exercise-induced muscle fatigue in people who exercise regularly. Twelve healthy participants who exercised regularly were enrolled in this study. Each participant completed an exercise-induced muscle fatigue test while wearing a randomly assigned lower-body CG or sports pants (SP); after at least 7 days, the participant repeated the test while wearing the other garment. The dependent variables were muscle efficacy, proprioception (displacements of center of pressure/COP, and absolute error), and fatigue recovery (muscle oxygen saturation/SmO2, deoxygenation and reoxygenation rate, and subjective muscle soreness). A two-way repeated measure analysis of variance was conducted to determine the effect of garment type. The results indicated that relative to SP use, CG use can promote muscle efficacy, proprioception in ML displacement of COP, and fatigue recovery. Higher deoxygenation and reoxygenation rates were observed with CG use than with SP use. For CG use, SmO2 quickly returned to baseline value after 10 min of rest and was maintained at a high level until after 1 h of rest, whereas for SP use, SmO2 increased with time after fatigue onset. ML displacement of COP quickly returned to baseline value after 10 min of rest and subsequently decreased until after 1 hour of rest. Relative to SP use, CG use was associated with a significantly lower ML displacement after 20 min of rest. In conclusion, proprioception and SmO2 recovery was achieved after 10 min of rest; however, at least 24 h may be required for recovery pertaining to muscle efficacy and soreness regardless of CG or SP use.

Genetic polymorphisms in CYP19A1 and ESR1 are associated with serum CK activity after prolonged running in men.

This study aimed to clarify 1) the influence of genetic polymorphisms in the cytochrome P450 aromatase gene (CYP19A1) on circulating estradiol levels in men and 2) whether estrogen-related genetic polymorphisms, such as the CYP19A1 rs936306 and estrogen receptor-α (ESR1) rs2234693 polymorphisms, predict exercise-induced serum creatine kinase (CK) activity, which is an index of skeletal muscle membrane disruption. Serum estradiol levels were examined in young men (n = 167). In a different cohort, serum CK activity was analyzed in a 2-day ultramarathon race: baseline, after the first day, and after the second day (114 males and 25 females). Genetic polymorphisms in CYP19A1 rs936306 C/T and ESR1 rs2234693 T/C were analyzed using the TaqMan SNP Genotyping Assay. Male subjects with the TT genotype of the CYP19A1 polymorphism exhibited significantly higher serum estradiol levels than the C allele carriers. Male runners had significantly higher postrace serum CK activity than female runners. The change in the CK activity during the ultramarathon race was significantly lower in male subjects with the CYP19A1 TT genotype than in those with the CC+CT genotypes and was correlated with the number of C alleles in ESR1 rs2234693 in male subjects. Furthermore, the genotype scores of these two polymorphisms were significantly correlated with changes in serum CK activity during race (r = -0.279, P = 0.003). The results of this study suggest that genetic polymorphisms in CYP19A1 rs936306 influence serum estradiol levels in men, and genetic polymorphisms in CYP19A1 and ESR1 are associated with serum CK activity in men.NEW & NOTEWORTHY Men with the TT genotype of the CYP19A1 polymorphism exhibited higher circulating estradiol levels than the TC+CC genotype. The TT genotype in the CYP19A1 polymorphism and the C allele of the ESR1 polymorphism, an allele increasing ESR1 expression, were associated with low serum CK activity after the ultramarathon. A combination of these polymorphisms was correlated with changes in the serum CK activity. Therefore, estrogen-related genetic polymorphisms partially predict exercise-induced muscle damage, that is, skeletal muscle membrane disruption.

Compression Garments for Recovery from Muscle Damage: Evidence and Implications of Dose Responses.

The use of compression garments (CG) has been associated with improved recovery following exercise-induced muscle damage. The mechanisms responsible are not well established, and no consensus exists regarding the effects of compression pressure (i.e., the "dose"), which until recently was seldom reported. With the increasing prevalence of studies reporting directly measured pressures, the present review aims to consolidate current evidence on optimal pressures for recovery from exercise-induced muscle damage. In addition, recent findings suggesting that custom-fitted garments provide greater precision and experimental control are discussed. Finally, biochemical data from human trials are presented to support a theoretical mechanism by which CG enhance recovery, with recommendations for future research. The effects of compression on adaptation remain unexplored. More studies are required to investigate the relationship between compression pressure and the recovery of performance and physiological outcomes. Furthermore, improved mechanistic understanding may help elucidate the optimal conditions by which CG enhance recovery.

Resveratrol administration reduces pain perception but does not attenuate force loss following exercise-induced muscle damage

Resveratrol administration reduces pain perception but does not attenuate force loss following exercise-induced muscle damage

Long-Term Combined Effects of Citrulline and Nitrate-Rich Beetroot Extract Supplementation on Recovery Status in Trained Male Triathletes: A Randomized, Double-Blind, Placebo-Controlled Trial.

Simple SummaryRecovery is one of the main elements in achieving adequate athletic performance. Various supplements have been used for this purpose. Citrulline (CIT) and Nitrate-Rich Beetroot Extract (BR) are so-called nitric oxide precursor supplements that have shown an ergogenic effect on sports performance when used on a short-term, individual basis. These supplements appear to have other pathways that may promote athletic performance. The purpose of this study was to assess the effect of a co-supplementation for 9 weeks of 3 g/day of CIT plus 2.1 g/day of BR (300 mg/day of nitrates) on recovery by exercise-induced muscle damage markers (EIMD), anabolic/catabolic hormones and distance covered in the Cooper test (CP). Thirty-two male triathletes were randomized into 4 groups of 8 in this double-blind, placebo-controlled trial: placebo group, CIT group, BR group and CIT-BR group. Blood samples and CP were collected at baseline and after 9 weeks. The main conclusions were the combination of 3 g/day of CIT plus 2.1 g/day of BR (300 mg/day of NO3−) supplementation for 9 weeks did not present any benefit for EIMD. However, CIT-BR improved recovery status by preventing an increase in cortisol and showing an increase in Testosterone/Cortisol ratio and distance covered in the CP.Citrulline (CIT) and nitrate-rich beetroot extract (BR) are widely studied ergogenic aids. Nevertheless, both supplements have been studied in short-term trials and separately. To the best of the authors’ knowledge, the effects of combining CIT and BR supplementation on recovery status observed by distance covered in the Cooper test, exercise-induced muscle damage (EIMD) and anabolic/catabolic hormone status have not been investigated to date. Therefore, the main purpose of this research was to assess the effect of the long-term (9 weeks) mixture of 3 g/day of CIT plus 2.1 g/day of BR (300 mg/day of nitrates (NO3−)) supplementation on recovery by distance covered in the Cooper test, EIMD markers (urea, creatinine, AST, ALT, GGT, LDH and CK) and anabolic/catabolic hormones (testosterone, cortisol and testosterone/cortisol ratio (T/C)) in male trained triathletes. Thirty-two triathletes were randomized into four different groups of eight triathletes in this double-blind, placebo-controlled trial: placebo group (PLG), CIT group (CITG; 3 g/day of CIT), BR group (BRG; 2.1 g/day of BR (300 mg/day of NO3−)) and CIT-BR group (CIT-BRG; 3 g/day of CIT plus 2.1 g/day of BR (300 mg/day of NO3−)). Distance covered in the Cooper test and blood samples were collected from all participants at baseline (T1) and after 9 weeks of supplementation (T2). There were no significant differences in the interaction between group and time in EIMD markers (urea, creatinine, AST, ALT, GGT, LDH and CK) (p > 0.05). However, significant differences were observed in the group-by-time interaction in distance covered in the Cooper test (p = 0.002; η2p = 0.418), cortisol (p = 0.044; η2p = 0.247) and T/C (p = 0.005; η2p = 0.359). Concretely, significant differences were observed in distance covered in the Cooper test percentage of change (p = 0.002; η2p = 0.418) between CIT-BRG and PLG and CITG, in cortisol percentage change (p = 0.049; η2p = 0.257) and in T/C percentage change (p = 0.018; η2p = 0.297) between CIT-BRG and PLG. In conclusion, the combination of 3 g/day of CIT plus 2.1 g/day of BR (300 mg/day of NO3−) supplementation for 9 weeks did not present any benefit for EIMD. However, CIT + BR improved recovery status by preventing an increase in cortisol and showing an increase in distance covered in the Cooper test and T/C.

Recovery from resistance exercise in older adults: a protocol for a scoping review

IntroductionResistance exercise has been shown to improve muscle health in older adults and is recommended as a front-line treatment for many health conditions, including sarcopenia and frailty. However, despite considerable...

American Ginseng Attenuates Eccentric Exercise-Induced Muscle Damage via the Modulation of Lipid Peroxidation and Inflammatory Adaptation in Males

Exercise-induced muscle damage (EIMD) is characterized by a reduction in functional performance, disruption of muscle structure, production of reactive oxygen species, and inflammatory reactions. Ginseng, along with its major bioactive component ginsenosides, has been widely employed in traditional Chinese medicine. The protective potential of American ginseng (AG) for eccentric EIMD remains unclear. Twelve physically active males (age: 22.4 ± 1.7 years; height: 175.1 ± 5.7 cm; weight: 70.8 ± 8.0 kg; peak oxygen consumption [peak] 54.1 ± 4.3 mL/kg/min) were administrated by AG extract (1.6 g/day) or placebo (P) for 28 days and subsequently challenged by downhill (DH) running (−10% gradient and 60% peak). The levels of circulating 8-iso-prostaglandin F 2α (PGF2α), creatine kinase (CK), interleukin (IL)-1β, IL-4, IL-10, and TNF-α, and the graphic pain rating scale (GPRS) were measured before and after supplementation and DH running. The results showed that the increases in plasma CK activity induced by DH running were eliminated by AG supplementation at 48 and 72 h after DH running. The level of plasma 8-iso-PGF2α was attenuated by AG supplementation immediately (p = 0.01 and r = 0.53), 2 h (p = 0.01 and r = 0.53) and 24 h (p = 0.028 and r = 0.45) after DH running compared with that by P supplementation. Moreover, our results showed an attenuation in the plasma IL-4 levels between AG and P supplementation before (p = 0.011 and r = 0.52) and 72 h (p = 0.028 and r = 0.45) following DH running. Our findings suggest that short-term supplementation with AG alleviates eccentric EIMD by decreasing lipid peroxidation and promoting inflammatory adaptation.

Dietary Supplementation for Attenuating Exercise-Induced Muscle Damage and Delayed-Onset Muscle Soreness in Humans.

Dietary supplements are widely used as a nutritional strategy to improve and maintain performance and achieve faster recovery in sports and exercise. Exercise-induced muscle damage (EIMD) is caused by mechanical stress and subsequent inflammatory responses including reactive oxygen species and cytokine production. Therefore, dietary supplements with anti-inflammatory and antioxidant properties have the potential to prevent and reduce muscle damage and symptoms characterized by loss of muscle strength and delayed-onset muscle soreness (DOMS). However, only a few supplements are considered to be effective at present. This review focuses on the effects of dietary supplements derived from phytochemicals and listed in the International Olympic Committee consensus statement on muscle damage evaluated by blood myofiber damage markers, muscle soreness, performance, and inflammatory and oxidative stress markers. In this review, the effects of dietary supplements are also discussed in terms of study design (i.e., parallel and crossover studies), exercise model, and such subject characteristics as physical fitness level. Future perspectives and considerations for the use of dietary supplements to alleviate EIMD and DOMS are also discussed.

The influence of muscle strength and aerobic fitness on functional recovery in professional soccer players.

Well-developed physical qualities may protect athletes from exercise-induced muscle damage and accelerate recovery following exercise. This study examined the influence of muscle strength and aerobic fitness on recovery from competitive soccer matches. Fourteen players from the English Premier League 2 (age 18±1 years; height 1.78±0.54 m; mass 73.8±6.3 kg) were equally divided (median split) into a higher or lower group for muscle strength and aerobic fitness, according to their isometric mid-thigh pull (IMPT) and maximal aerobic speed test (MAST) scores, respectively. The following markers of recovery were assessed before (48-h prematch), 12 h (M+1), 36 h (M+2) and 60 h (M+3) after ~3 matches: countermovement jump height (CMJ), reactive strength index (RSI), muscle soreness (DOMS) and wellbeing. IMTP was positively correlated with the recovery of CMJ, RSI and DOMS following matches (P<0.05). In the high IMTP group, DOMS was lower at M+1 to M+3 (all P≤0.002; ES≥2.10), CMJ was ≥4% greater at M+1 to M+3 (all P≤0.001; ES≥2.21) and RSI was ≥3% higher at M+2 and M+3 (all P≤0037; ES≥1.25). Players in the H-MAST group did not recover quicker for any variable (all P>0.05). This study showed that stronger players recovered quicker after matches and highlights the importance of lower-body strength training for soccer players.

Effect of a sulforaphane supplement on muscle soreness and damage induced by eccentric exercise in young adults: A pilot study.

ObjectiveExcessive exercise increases the production of reactive oxygen species in skeletal muscles. Sulforaphane activates nuclear factor erythroid 2‐related factor 2 (Nrf2) and induces a protective effect against oxidative stress. In a recent report, sulforaphane intake suppressed exercise‐induced oxidative stress and muscle damage in mice. However, the effect of sulforaphane intake on delayed onset muscle soreness after eccentric exercise in humans is unknown. We evaluated the effect of sulforaphane supplement intake in humans regarding the delayed onset muscle soreness (DOMS) after eccentric exercise.Research Methods & ProceduresTo determine the duration of sulforaphane supplementation, continuous blood sampling was performed and NQO1 mRNA expression levels were analyzed. Sixteen young men were randomly divided into sulforaphane and control groups. The sulforaphane group received sulforaphane supplements. Each group performed six set of five eccentric exercise with the nondominant arm in elbow flexion with 70% maximum voluntary contraction. We assessed muscle soreness in the biceps using the visual analog scale, range of motion (ROM), muscle damage markers, and oxidative stress marker (malondialdehyde; MDA).ResultsSulforaphane supplement intake for 2 weeks increased NQO1 mRNA expression in peripheral blood mononuclear cells (PBMCs). Muscle soreness on palpation and ROM were significantly lower 2 days after exercise in the sulforaphane group compared with the control group. Serum MDA showed significantly lower levels 2 days after exercise in the sulforaphane group compared with the control group.ConclusionOur findings suggest that sulforaphane intake from 2 weeks before to 4 days after the exercise increased NQO1, a target gene of Nrf2, and suppressed DOMS after 2 days of eccentric exercise.

Differential Autophagy Response in Men and Women After Muscle Damage.

Following muscle damage, autophagy is crucial for muscle regeneration. Hormones (e.g., testosterone, cortisol) regulate this process and sex differences in autophagic flux exist in the basal state. However, to date, no study has examined the effect of a transient hormonal response following eccentric exercise-induced muscle damage (EE) between untrained young men and women. Untrained men (n = 8, 22 ± 3 years) and women (n = 8, 19 ± 1 year) completed two sessions of 80 unilateral maximal eccentric knee extensions followed by either upper body resistance exercise (RE; designed to induce a hormonal response; EE + RE) or a time-matched rest period (20 min; EE + REST). Vastus lateralis biopsy samples were collected before (BL), and 12 h, and 24 h after RE/REST. Gene and protein expression levels of selective markers for autophagic initiation signaling, phagophore initiation, and elongation/sequestration were determined. Basal markers of autophagy were not different between sexes. For EE + RE, although initiation signaling (FOXO3) and autophagy-promoting (BECN1) genes were greater (p < 0.0001; 12.4-fold, p = 0.0010; 10.5-fold, respectively) for women than men, autophagic flux (LC3-II/LC3-I protein ratio) did not change for women and was lower (p < 0.0001 3.0-fold) than men. Furthermore, regardless of hormonal changes, LC3-I and LC3-II protein content decreased (p = 0.0090; 0.547-fold, p = 0.0410; 0.307-fold, respectively) for men suggesting increased LC3-I lipidation and autophagosome degradation whereas LC3-I protein content increased (p = 0.0360; 1.485-fold) for women suggesting decreased LC3-I lipidation. Collectively, our findings demonstrated basal autophagy was not different between men and women, did not change after EE alone, and was promoted with the acute hormonal increase after RE only in men but not in women. Thus, the autophagy response to moderate muscle damage is promoted by RE-induced hormonal changes in men only.