Metabolic consequences of exercise-induced muscle damage

Prolonged running reduces speed at the moderate-to-heavy intensity transition without additional reductions due to increased eccentric load

AIM

To investigate the impact of prolonged running on speed at the moderate-to-heavy intensity transition, and whether increased eccentric load modifies exercise-induced shifts in the moderate-to-heavy intensity transition.

METHODS

Twelve endurance-trained runners (4 females, 8 males, peak oxygen uptake 51.5 mL kg-1 min-1 in females and 56.1 mL kg-1 min-1 in males) participated. Following trials to assess speed at the first ventilatory threshold (VT1) on a 0% gradient and -10% gradient, participants completed two trials: (i) level trial (LVL): 120-min of running at 0% gradient and (ii) downhill trial (DH): 120-min of running with 90-min at 0% gradient and 6 × 5-min intervals at -10% gradient (DH). Running was conducted at 90% of VT1 speed for respective gradients. Speed at VT1 on 0% gradient, perceived leg muscle soreness, and maximal voluntary isometric knee extensor torque were assessed pre- and post-prolonged exercise.

RESULTS

An effect of time was observed for speed at VT1 (∆-6.2 ± 3.6% in LVL and ∆-7.6 ± 3.2% in DH, P < 0.001), with no effect of condition (LVL vs. DH, P = 0.382), or time × condition interaction (P = 0.295). Reduced metabolic energy expenditure (metabolic power) significantly contributed to the reduced speed at VT1 in both trials (P < 0.001), whereas changes in running economy (energetic efficiency) did not (P = 0.228).

CONCLUSION

Prolonged moderate-intensity running reduced speed at the moderate-to-heavy intensity transition, but this was not exacerbated by increased eccentric load. Reduced speed at the moderate-to-heavy intensity transition following prolonged running was primarily attributed to decreased metabolic power.

The role of resistance exercise-induced local metabolic stress in mediating systemic health and functional adaptations: could condensed training volume unlock greater benefits beyond time efficiency?

The majority of "specialised" exercise configurations (e.g., supersets, drop sets, blood flow restriction) are being assessed as "shortcuts" to hypertrophy and strength improvements. However, these advanced training techniques may also offer significant benefits for systemic health and functional outcomes across recreational and clinical populations via locally induced metabolic responses. Stress-regulating mechanisms are known to enhance the body's resilience by facilitating allostasis, the process of coordinating adaptive processes in reaction to stressors such as physical training. Yet, the role of the local metabolic stress provoked by resistance exercise has not gained much research attention despite its wide potential. Positive effects are not only linked to improved muscular endurance, hypertrophy and strength via primary and secondary mechanisms, but also to the release of myokines, hormones, microRNAs, immune factors, inflammatory substances and other endocrine molecules that initiate numerous health-promoting modifications on a systemic level. Resistance exercise strategies that maximise the local accumulation of metabolites are not well defined, although high volume, close proximity to failure and shorter rests seem to be a necessity. Additionally, blood flow restriction training provides a potent alternative for inducing local acidosis, thereby triggering several pathways associated with improved immunity and physical function even in remote muscle tissues. Future research is warranted to further explore advanced resistance training techniques, as these approaches may offer comparable benefits for physical and mental health to those seen with other forms of exercise such as high-intensity interval training and heavy resistance training.

Polyphenols and post-exercise muscle damage: a comprehensive review of literature

Recent research highlights the significant role of polyphenols in alleviating post-exercise muscle damage, thus positioning them as a valuable nutritional strategy for athletes and fitness enthusiasts. Polyphenols, naturally occurring bioactive compounds abundant in fruits, vegetables, tea, wine, and other plant-based foods, are recognized for their potent antioxidant and anti-inflammatory properties. This dual mechanism is critical for combating oxidative stress and inflammation-two factors that intensify during vigorous physical activity and contribute to muscle soreness and damage. Among various polyphenols, compounds like quercetin have particularly emerged as effective agents for promoting muscle recovery and enhancing exercise performance. These protective effects are facilitated through several mechanisms, including the modulation of inflammatory pathways, acceleration of muscle repair processes, and enhancement of mitochondrial function, all of which bolster overall muscle health. As ongoing studies yield deeper insights, the potential of polyphenols to enhance athletic performance and overall health will become increasingly substantiated, leading towards their strategic incorporation into exercise nutrition protocols. Therefore, we reviewed relevant studies in order to show how efficient polyphenols can be in reducing muscle fatigue and damage and what are the exact mechanisms.

Recycle, repair, recover: the role of autophagy in modulating skeletal muscle repair and post-exercise recovery

Skeletal muscle is a highly plastic tissue that can adapt relatively rapidly to a range of stimuli. In response to novel mechanical loading, e.g. unaccustomed resistance exercise, myofibers are disrupted and undergo a period of ultrastructural remodeling to regain full physiological function, normally within 7 days. The mechanisms that underpin this remodeling are believed to be a combination of cellular processes including ubiquitin-proteasome/calpain-mediated degradation, immune cell infiltration, and satellite cell proliferation/differentiation. A relatively understudied system that has the potential to be a significant contributing mechanism to repair and recovery is the autophagolysosomal system, an intracellular process that degrades damaged and redundant cellular components to provide constituent metabolites for the resynthesis of new organelles and cellular structures. This review summarizes our current understanding of the autophagolysosomal system in the context of skeletal muscle repair and recovery. In addition, we also provide hypothetical models of how this system may interact with other processes involved in skeletal muscle remodeling and provide avenues for future research to improve our understanding of autophagy in human skeletal muscle.

A Multi-ingredient Supplement Reduced Markers of Muscle Damage after a Rugby Match in Collegiate Male Players

ABSTRACT

Eccentric exercise and collisions that lead to muscle damage are common place among athletes. This study aimed to investigate the effect of a multi-ingredient supplement (MIS), containing the extracts of turmeric, chicken meat, and apple and ancient peat, on markers of muscle damage in collegiate male players following a rugby match. A position-matched, double-blind, randomized, and crossover design was employed in this study. Each trial consisted of a 14-day supplementation period, followed by a 15-a-side rugby match. A total of 13 participants, eight forward and five backs, with a mean height of 1.76 ± 0.08 m and a mean weight of 86.0 ± 22.8 kg, were included. Blood samples were collected before, immediately, 24 h, and 48 h after the match. Both the MIS ( P < 0.001, d = 1.86) and placebo trials ( P = 0.002, d = 1.97) exhibited a significant increase in plasma creatine kinase and lactate dehydrogenase (LDH) concentrations from the baseline immediately after the match. However, plasma creatine kinase concentration in the MIS trial was significantly lower at 24 h postmatch compared to the placebo trial ( P = 0.029, d = 0.90). Moreover, plasma LDH concentration returned to the baseline level 24 h after the match in the MIS trial, while it remained elevated in the placebo trial ( P = 0.001, d = 1.07). In either trials, the plasma tumor necrosis factor-α and malondialdehyde concentrations were not significantly different. In conclusion, the MIS can alleviate muscle damage markers after a rugby match without changes in inflammation and oxidative stress markers.

Indices of exercise induced muscle damage following low load resistance exercise with blood flow restriction in untrained males

BACKGROUND

There is conflicting evidence regarding the presence and magnitude of exercise-induced muscle damage (EIMD) following low-load resistance training with blood flow restriction (LL+BFR), which may be related to the protocol implemented or exercise volume. Therefore, the purpose of this investigation was to examine the effects of a 75 repetition (BFR-75) (1×30, 3×15) and four sets to volitional failure (BFR-4x) protocols on indices of EIMD among untrained men.

METHODS

Twelve males with no history of lower-body resistance training during the previous six months volunteered for this investigation. One leg was randomly assigned to BFR-75, and the other to BFR-4x. Participants performed isokinetic, unilateral, concentric-eccentric, leg extension muscle actions at 30% of maximal strength with BFR. Indices of EIMD (limb circumference, perceived muscle soreness, pain pressure threshold [PPT], passive range of motion, and maximal strength [MVIC]) were recorded before exercise and 0, 24, 48, 72, and 96-hours post-exercise for each protocol.

RESULTS

There were no significant changes (P>0.05) in limb circumference, PPT, passive range of motion, or MVIC. For both BFR-75 and BFR-4x, perceived muscle soreness increased (P<0.001) similarly 24- (2.5±1.7 AU) and 48-hours (1.9±1.7 AU) post-exercise.

CONCLUSIONS

There was an increase in muscle soreness 24-48 hours post-exercise for both conditions, which may be due to metabolic stress, but this did not affect the force-generating capacity of the muscle (MVIC), suggesting minimal EIMD. The conflicting evidence of EIMD following LL+BFR may be related to differences in restriction time or overall exercise time.

Temporal tracking of cysteine 34 oxidation of plasma albumin as a biomarker of muscle damage following a bout of eccentric exercise

PURPOSE

Exercise-induced muscle damage (EIMD) results in the generation of reactive oxygen species (ROS), but little is known about the temporal profile of change in ROS post-EIMD and how ROS levels relate to the onset of and recovery from EIMD. Our primary aim was to examine the effect of EIMD on the pattern of change in the blood level of thiol-oxidised albumin, a marker of oxidative stress.

METHODS

Seven male participants were subjected on separate days to eccentric muscle contraction to cause EIMD or a no-exercise condition. After each session, the participants collected daily dried blood spots to measure thiol-oxidised albumin and returned to the laboratory every 2 days for the assessment of indirect markers of EIMD, namely maximal voluntary contraction (MVC), delayed onset muscle soreness (DOMS), creatine kinase (CK), and myoglobin.

RESULTS

Eccentric exercise resulted in a significant decrease in MVC and increase in DOMS, CK, myoglobin, and thiol-oxidised albumin with the latter reaching above baseline level within 24-48 h post-exercise. All the markers of EIMD returned to baseline level within 6 days post-exercise, but not the level of thiol-oxidised albumin which remained elevated for 10 days after exercise. There was a moderate correlation between changes in thiol-oxidised albumin and DOMS, but no significant relationship between any other markers of muscle damage.

CONCLUSION

The levels of thiol-oxidised albumin increase in response to EIMD and remain elevated for several days post-exercise. The temporal pattern of change in the level of thiol-oxidised albumin suggests that this may be a useful biomarker of muscle repair post-EIMD.

Vitamin E Does not Favor Recovery After Exercises: Systematic Review and Meta-analysis

This review aimed to verify the effects of vitamin E supplementation on oxidative stress, inflammatory response, muscle damage, soreness, and strength in healthy adults after exercise. We searched the MEDLINE, EMBASE, SPORTDiscus, Cochrane CENTRAL, and Web of Science from inception to August 2023, with no language restrictions. We included randomized placebo-controlled trials evaluating the supplementation of vitamin E on the abovementioned outcomes after a bout of physical exercise in healthy participants (no restriction for publication year or language). Meta-analyses were conducted to compare vitamin E and placebo supplementations to obtain a 95% confidence interval (95%IC). Twenty studies were included (n=298 participants). The effect of supplementation was assessed between 0 h and 96 h after the exercise. Compared to placebo, vitamin E had no effects on lipid (95%IC= -0.09 to 0.42), protein (-2.44 to 3.11), SOD (-1.05 to 0.23), interleukin-6 (-0.18 to 1.16), creatine kinase (-0.33 to 0.27), muscle soreness (-1.92 to 0.69), and muscle strength (-1.07 to 0.34). Heterogeneity for the analyses on carbonyls, interleukin-6 (1 h and 3 h), and muscle soreness ranged between 70 to 94%. Supplementing with vitamin E should not be recommended to support the recovery process in healthy individuals after exercise, given the lack of efficacy in the analyzed variables following an exercise session.

Apelin regulates skeletal muscle adaptation to exercise in a high-intensity interval training model

Plasma apelin levels are reduced in aging and muscle wasting conditions. We aimed to investigate the significance of apelin signaling in cardiac and skeletal muscle responses to physiological stress. Apelin knockout (KO) and wild-type (WT) mice were subjected to high-intensity interval training (HIIT) by treadmill running. The effects of apelin on energy metabolism were studied in primary mouse skeletal muscle myotubes and cardiomyocytes. Apelin increased mitochondrial ATP production and mitochondrial coupling efficiency in myotubes and promoted the expression of mitochondrial genes both in primary myotubes and cardiomyocytes. HIIT induced mild concentric cardiac hypertrophy in WT mice, whereas eccentric growth was observed in the left ventricles of apelin KO mice. HIIT did not affect myofiber size in skeletal muscles of WT mice but decreased the myofiber size in apelin KO mice. The decrease in myofiber size resulted from a fiber type switch toward smaller slow-twitch type I fibers. The increased proportion of slow-twitch type I fibers in apelin KO mice was associated with upregulation of myosin heavy chain slow isoform expression, accompanied with upregulated expression of genes related to fatty acid transport and downregulated expression of genes related to glucose metabolism. Mechanistically, skeletal muscles of apelin KO mice showed defective induction of insulin-like growth factor-1 signaling in response to HIIT. In conclusion, apelin is required for proper skeletal and cardiac muscle adaptation to high-intensity exercise. Promoting apelinergic signaling may have benefits in aging- or disease-related muscle wasting conditions.NEW & NOTEWORTHY Apelin levels decline with age. This study demonstrates that in trained mice, apelin deficiency results in a switch from fast type II myofibers to slow oxidative type I myofibers. This is associated with a concomitant change in gene expression profile toward fatty acid utilization, indicating an aged-muscle phenotype in exercised apelin-deficient mice. These data are of importance in the design of exercise programs for aging individuals and could offer therapeutic target to maintain muscle mass.

Hydrogen-rich water supplementation promotes muscle recovery after two strenuous training sessions performed on the same day in elite fin swimmers: randomized, double-blind, placebo-controlled, crossover trial

Purpose: Molecular hydrogen has been shown to possess antioxidant, anti-inflammatory, ergogenic, and recovery-enhancing effects. This study aimed to assess the effect of molecular hydrogen administration on muscle performance, damage, and perception of soreness up to 24 h of recovery after two strenuous training sessions performed on the same day in elite fin swimmers. Methods: Eight females (mean ± SD; age 21.5 ± 5.0 years, maximal oxygen consumption 45.0 ± 2.5 mL.kg-1.min-1) and four males (age 18.9 ± 1.3 years, maximal oxygen consumption 52.2 ± 1.7 mL.kg-1.min-1) performed 12 × 50 m sprints in the morning session and a 400 m competitive performance in the afternoon session. Participants consumed hydrogen-rich water (HRW) or placebo 3 days before the sessions (1,260 mL/day) and 2,520 mL on the experimental day. Muscle performance (countermovement jump), muscle damage (creatine kinase), and muscle soreness (100 mm visual analogue scale) were measured during the experimental day and at 12 and 24 h after the afternoon session. Results: HRW compared to placebo reduced blood activity of creatine kinase (156 ± 63 vs. 190 ± 64 U.L-1, p = 0.043), muscle soreness perception (34 ± 12 vs. 42 ± 12 mm, p = 0.045), and improved countermovement jump height (30.7 ± 5.5 cm vs. 29.8 ± 5.8 cm, p = 0.014) at 12 h after the afternoon session. Conclusion: Four days of HRW supplementation is a promising hydration strategy for promoting muscle recovery after two strenuous training sessions performed on the same day in elite fin swimmers. Clinical Trial Registration: clinicaltrials.gov, identifier NCT05799911.

Age-Associated Differences in Recovery from Exercise-Induced Muscle Damage

Understanding the intricate mechanisms governing the cellular response to resistance exercise is paramount for promoting healthy aging. This narrative review explored the age-related alterations in recovery from resistance exercise, focusing on the nuanced aspects of exercise-induced muscle damage in older adults. Due to the limited number of studies in older adults that attempt to delineate age differences in muscle discovery, we delve into the multifaceted cellular influences of chronic low-grade inflammation, modifications in the extracellular matrix, and the role of lipid mediators in shaping the recovery landscape in aging skeletal muscle. From our literature search, it is evident that aged muscle displays delayed, prolonged, and inefficient recovery. These changes can be attributed to anabolic resistance, the stiffening of the extracellular matrix, mitochondrial dysfunction, and unresolved inflammation as well as alterations in satellite cell function. Collectively, these age-related impairments may impact subsequent adaptations to resistance exercise. Insights gleaned from this exploration may inform targeted interventions aimed at enhancing the efficacy of resistance training programs tailored to the specific needs of older adults, ultimately fostering healthy aging and preserving functional independence.

Effect of blood flow restriction with low-load exercise on muscle damage in healthy adults: A systematic review of randomized controlled trials

INTRODUCTION

Blood flow restriction (BFR) is a relatively new rehabilitative technique and low-load exercise combined with BFR (LL-BFR) can increase muscle strength and muscle mass. However, it is currently unknown whether LL-BFR causes muscle damage. Therefore, the aim of this study is to investigate the effects of LL-BFR on muscle damage and provide recommendations for sports training and physical exercise.

MATERIALS AND METHODS

A systematic search was conducted using PubMed, Web of Science, Medline, Cochrane Library and Physiotherapy Evidence Database (PEDro) with a cut-off of March 2022. Randomized controlled trials (RCTs) and English-language studies were selected. Two independent assessors used the PEDro scoring scale to evaluate the methodological quality and risk of bias of the included studies.

RESULTS

Of the 2935 articles identified, 15 RCTs were included in this systematic review. Two studies demonstrated that LL-BFR could induce muscle damage in healthy individuals; however, two studies presented contrasting findings in the short term. Four studies found that no muscle damage occurred after LL-BFR in the long term. The remaining seven articles showed that it was unclear if LL-BFR could cause muscle damage, regardless of whether these participants were trained or not.

CONCLUSION

Although LL-BFR may induce muscle damage within 1 week, it will help gain long-term muscle strength and muscle hypertrophy. However, the lack of sufficient evidence on the effect of LL-BFR on muscle damage in clinical practice warrants additional RCTs with large sample sizes in the future.

Assessment of selected muscle damage markers and zonulin concentration after maximum-intensity exercise in men with type 1 diabetes treated with a personal insulin pump

AIM

Exercise-induced muscle damage depends on exercise intensity and duration and on individual susceptibility. Mechanical and metabolic stress may disturb the intestinal microflora. The study evaluated selected muscle damage markers and zonulin concentration after maximum-intensity exercise in type 1 diabetes (T1D) men compared with healthy controls.

METHODS

The study involved 16 T1D participants and 28 controls matched by age (22.7 [21.3-25.1] vs. 22.6 [20.9-26.3] years), body mass index (24.2 ± 1.6 vs. 24.2 ± 1.9 kg/m2), and body fat percentage (16.1 ± 5.2 vs. 14.9 ± 4.6%). The T1D group had 11.3 ± 5.1 years of diabetes duration and a suboptimal mean glycated haemoglobin level of 7.2 ± 1.1%. The subjects underwent a graded running treadmill test until exhaustion. Lactate concentration was assessed in arterialized blood at baseline and 3 and 20 min after the test. Cortisol, testosterone, tumour necrosis factor α, myoglobin, lactate dehydrogenase, zonulin, and vitamin D levels were evaluated in cubital fossa vein blood before and 60 min after the test.

RESULTS

T1D patients presented higher baseline zonulin, myoglobin concentration, testosterone/cortisol ratio, and lower maximal oxygen uptake. On adjusting for the baseline values, the groups differed in zonulin, lactate dehydrogenase, and myoglobin levels, testosterone/cortisol ratio, and lactate concentration determined 20 min after exercise (P < 0.05).

CONCLUSION

Maximum-intensity exercise increased muscle and intestinal damage in T1D participants. In patients with lower physical activity, very-high-intensity exercise should be recommended with caution. Observing the anabolic-catabolic index may help individualize effort intensity in T1D individuals.

Exercise-Induced Muscle Damage after a High-Intensity Interval Exercise Session: Systematic Review

High-intensity interval training (HIIT) is considered an effective method to improve fitness and health indicators, but its high-intensity exercises and the mechanical and metabolic stress generated during the session can lead to the occurrence of exercise-induced muscle damage. Therefore, this study aimed to describe, by means of a systematic review, the effects of a single HIIT session on exercise-induced muscle damage. A total of 43 studies were found in the Medline/PubMed Science Direct/Embase/Scielo/CINAHL/LILACS databases; however, after applying the exclusion criteria, only 15 articles were considered eligible for this review. The total sample was 315 participants. Among them, 77.2% were men, 13.3% were women and 9.5 uninformed. Their age ranged from 20.1 ± 2 to 47.8 ± 7.5 years. HIIT protocols included running with ergometers (n = 6), CrossFit-specific exercises (n = 2), running without ergometers (n = 3), swimming (n = 1), the Wingate test on stationary bicycles (n = 2), and cycling (n = 1). The most applied intensity controls were %vVO2max, "all out", MV, MAV, Vmax, and HRreserve%. The most used markers to evaluate muscle damage were creatine kinase, myoglobin, and lactate dehydrogenase. The time for muscle damage assessment ranged from immediately post exercise to seven days. HIIT protocols were able to promote changes in markers of exercise-induced muscle damage, evidenced by increases in CK, Mb, LDH, AST, ALT, pain, and muscle circumference observed mainly immediately and 24 h after the HIIT session.

75-repetition versus sets to failure of blood flow restriction exercise on indices of muscle damage in women

ABSTRACTThere is conflicting evidence regarding the prevalence and magnitude of exercise-induced muscle damage (EIMD) following low-load resistance exercise with blood flow restriction (LL + BFR) that may be related to exercise protocols. The purpose of this investigation was to examine the effects of 75-repetition (BFR-75) (1 × 30, 3 × 15) and 4 sets to failure (BFR-4x) protocols on indices of EIMD among untrained women. Thirteen women completed this investigation. One leg was randomly assigned to BFR-75 and the other to BFR-4x. Each leg performed isokinetic, unilateral, concentric-eccentric, leg extension muscle actions at 30% of maximal strength. Indices of EIMD (muscle soreness, range of motion [ROM], limb circumference, pain pressure threshold [PPT], and maximal voluntary isometric contraction [MVIC]) were recorded before exercise, 0-, 24-, 48-, 72-, and 96-hours post-exercise. There were no changes for ROM, circumference, or PPT. Muscle soreness increased similarly in both conditions 0-, 24-, and 48-hours post-exercise and MVIC increased 24-, 48-, 72-, and 96-hours post-exercise. These findings suggested BFR-75 and BFR-4x were not associated with EIMD and elicited similar physiological responses. The increases in muscle soreness may be due to metabolic stress associated with LL + BFR protocols apart from EIMD.

Association between serum zinc levels and suicidal ideation in US adults: A population-based cross-sectional study

BACKGROUND

Evidence suggests that the homeostatic disruption of zinc, copper, and selenium might contribute to the pathophysiology of mental disorders. However, the specific relationship between the serum levels of these trace elements with suicidal ideation remains poorly understood. This study aimed to investigated the association among suicidal ideation on serum levels of zinc, copper, and selenium.

METHODS

The cross-sectional study was conducted using data from a nationally representative sample of the National Health and Nutrition Examination Survey (NHANES) 2011-2016. Suicidal ideation was assessed using Item #9 of the Patient Health Questionnaire-9 Items. Multivariate regression models and restricted cubic splines were performed and E-value was calculated.

RESULTS

A total of 4561 participants aged 20 years and older were analyzed, of whom 4.08 % had suicidal ideation. The serum zinc levels were lower in the suicidal ideation group than in the non-suicidal ideation group (P = 0.021). In Crude Model, the serum zinc levels were associated with a higher suicidal ideation risk in the second quartile compared with the highest quartile [odds ratio (OR) = 2.63; 95 % confidence interval (CI): 1.53-4.53]. The association persisted (OR = 2.35; 95 % CI: 1.20-4.58) after full adjustment, with E-value 2.44. A nonlinear relationship was observed between serum zinc levels and suicidal ideation (P = 0.028). No relationship was observed between suicidal ideation and serum copper or selenium levels (all P > 0.05).

CONCLUSIONS

Decreased serum zinc levels may increase susceptibility to suicidal ideation. Future studies are needed to validate the findings of this study.

Impact of Antarctic krill oil supplementation on skeletal muscle injury recovery after resistance exercise

BACKGROUND

Antarctic krill oil (KO) is a natural source of n-3 polyunsaturated fatty acids (n-3 PUFAs), and is rich in phospholipids, Eicosapentaenoic acid (EPA), Docosahexaenoic acid (DHA), astaxanthin, flavonoids, vitamins, trace elements, and other bioactive substances. KO has been confirmed to have anti-inflammatory and immunomodulatory effects. n-3 PUFAs also have been purported to improve the recovery of muscular performance. Moreover, the phospholipids present in KO can enhance n-3 PUFA bioavailability because of its higher absorption rate in plasma compared to fish oil. Astaxanthin, found in Antarctic KO, is a red carotenoid and powerful antioxidant that inhibits oxidative stress after intense exercise. Hence, we examined the effect of KO supplementation on the recovery of exercise by measuring muscular performance, oxidant/antioxidant and anti-inflammatory activity, and the markers of muscle damage following a rigorous bout of resistance exercise.

METHODS

30 college-aged resistance-trained males (20.4 ± 0.92 years, 74.09 ± 7.23 kg, 180.13 ± 4.72 cm) were randomly supplemented with 3 g/d KO or placebo (PL) for 3 days and continued to consume after resistance exercise for 3 days until the experiment finished. Before supplementation, pre-exercise performance assessments of knee isokinetic strength, 20 m sprint, hexagon test, and blood serum creatine kinase (CK), lactate dehydrogenase (LDH), superoxide dismutase (SOD), total antioxidant capacity (T-AOC), reactive oxygen species (ROS), malondialdehyde (MDA), interleukin-2 (IL-2), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) were completed. Then after 3 days of supplementation, participants completed a bout of muscle-damaging exercise, and subsequently, they performed and repeated the exercise performance assessments and blood-related indicators tests immediately (0 h), as well as at 6, 24, 48, and 72 h post-muscle-damaging exercise.

RESULTS

Compared to the PL group, the serum CK of KO group was significantly lower at 24 h and 48 h post-exercise; the hexagon test time of the KO group was significantly lower than that of the PL group at 6 h and 24 h post-exercise; the KO group's isokinetic muscle strength showed different degrees of recovery than that of the PL group at 24 h and 48 h, and even over-recovery at 72 h post-exercise; the SOD level of the KO group was significantly higher than that of the PL group at 0, 6, and 24 h after exercise; the T-AOC level of the KO group was significantly higher than that of the PL group at 0, 6, and 72 h after exercise; the MDA level of the KO group was significantly lower than that of the PL group at 6 h; and there was no significant difference in serum IL-2, IL-6, and TNF-α between the two groups.

CONCLUSION

Our results demonstrated that 3 g/d KO supplementation and continued supplementation after exercise can alleviate exercise-induced muscle damage (EIMD) and promote post-exercise recovery.

The effect of dietary anthocyanins on biochemical, physiological, and subjective exercise recovery: a systematic review and meta-analysis

Anthocyanins (ACN), the sub-class of (poly)phenols responsible for the red-blue-purple pigmentation of fruit and vegetables, have gained considerable interest in sport and exercise research due to their potential to facilitate exercise recovery. A systematic literature search was performed using PubMed, The Cochrane Library, MEDLINE, SPORTDiscus and CINAHL. Thirty nine studies were included and the standardized mean difference (Hedges g) for creatine kinase (CK), anti-oxidative and inflammatory markers, strength, power and delayed onset muscle soreness (DOMS) indices were pooled in separate meta-analyses; meta-regression was also performed on reported ACN dose. Immediately post-exercise there was an increase in antioxidant capacity (g: 0.56) and reduced C reactive protein (g: -0.24) and tumor necrosis factor α (g: -40); p ≤ 0.02. Strength was improved with ACN at all time points (g: 0.45-0.67). DOMS (g: -0.23) was lower 24 hours post-exercise and power was improved 24 hours (g: 0.62) and 48 hours (g: 0.57) post exercise. The CK was lower 48 hours post-exercise (g: -0.31) and there was a trend for a positive association with ACN dose (p = 0.057). This systematic review provides new data showing ACN-rich foods promote functional and subjective recovery likely due to the antioxidant and anti-inflammatory properties of ACN.

Impact of cancer cachexia on respiratory muscle function and the therapeutic potential of exercise

Cancer cachexia is defined as a multi-factorial syndrome characterised by an ongoing loss of skeletal muscle mass and progressive functional impairment, estimated to affect 50-80% of patients and responsible for 20% of cancer deaths. Elevations in the morbidity and mortality rates of cachectic cancer patients has been linked to respiratory failure due to atrophy and dysfunction of the ventilatory muscles. Despite this, there is a distinct scarcity of research investigating the structural and functional condition of the respiratory musculature in cancer, with the majority of studies exclusively focusing on limb muscle. Treatment strategies are largely ineffective in mitigating the cachectic state. It is now widely accepted that an efficacious intervention will likely combine elements of pharmacology, nutrition and exercise. However, of these approaches, exercise has received comparatively little attention. Therefore, it is unlikely to be implemented optimally, whether in isolation or combination. In consideration of these limitations, the current review describes the mechanistic basis of cancer cachexia and subsequently explores the available respiratory- and exercise-focused literature within this context. The molecular basis of cachexia is thoroughly reviewed. The pivotal role of inflammatory mediators is described. Unravelling the mechanisms of exercise-induced support of muscle via antioxidant and anti-inflammatory effects in addition to promoting efficient energy metabolism via increased mitochondrial biogenesis, mitochondrial function and muscle glucose uptake provide avenues for interventional studies. Currently available pre-clinical mouse models including novel transgenic animals provide a platform for the development of multi-modal therapeutic strategies to protect respiratory muscles in people with cancer.

A combination of cherry juice and cold water immersion does not enhance marathon recovery compared to either treatment in isolation: A randomized placebo-controlled trial

Purpose

Cherry juice (CJ) and cold water immersion (CWI) are both effective recovery strategies following strenuous endurance exercise. However, athletes routinely combine recovery interventions and less is known about the impact of a combined CJ and CWI protocol. Therefore, this study investigated the effects of combining CWI and CJ (a “cocktail” (CT)) on inflammation and muscle damage following a marathon.

Methods

A total 39 endurance trained males were randomly assigned to a placebo (PL), CWI, CJ, or CT group before completing a trail marathon run. Muscle damage (creatine kinase (CK)), muscle function (maximal voluntary isometric contraction (MVIC)), and inflammation (interleukin-6 (IL-6); C-reactive protein (CRP)) were measured at baseline, immediately after marathon (only IL-6), 24 h, and 48 h after marathon.

Results

There were no statistically significant differences between groups and no group × time interaction effects for any of the dependent variables. Confidence intervals (CI) illustrated that CT had unclear effects on inflammation (IL-6; CRP) and MVIC, but may have increased CK to a greater extent than PL and CJ conditions.

Conclusion

There is no evidence of an additive effect of CJ and CWI when the treatments are used in conjunction with each other. On the contrary, combining CJ and CWI may result in slightly increased circulating CK.

Effect of Sodium Bicarbonate Supplementation on Muscle Performance and Muscle Damage: A Double Blind, Randomized Crossover Study

Sodium bicarbonate (NaHCO3) has been used as an ergogenic substance during high-intensity exercises. Therefore, the aim of the present study was to investigate the effects of NaHCO3 supplementation on external and internal load parameters during isokinetic exercise in trained subjects. Ten subjects were tested on two occasions: after ingesting 0.3 g.kg-1 of body mass of NaHCO3 or placebo. Maximum voluntary isometric contraction was performed before and after a dynamic protocol consisting of 10 series of 10 movements of flexion/extension of the knee extensors at 120° s-1 at an interval of 60 s between series. Outcomes considered were: peak torque (isokinetic dynamometry), blood lactate and creatine concentration (CK), analysis of perceptions of effort (OMNI scale), pain (visual analog scale) and recovery (scale raging 6 to 20). Performance was assessed using peak torque values. Muscle damage was assessed prior and 24 h post exercise. The subjective perceptions of effort, pain and recovery were assessed at different times and the internal load of the session was assessed 30 min post-effort. Although significant reductions in peak torque were noted both in isometric (NaHCO3:-29.11 ± 22.95%, Placebo: -23.51 ± 15.23%; p = 0.38) and isokinetic strength (NaHCO3:-23.0 ± 13.9%, Placebo:-19.6 ± 9.1%; p = 0.09), there was no effect of supplementation on performance (p > 0.05). The blood CK concentrations (NaHCO3: pre:225.3 ± 135.9 U/L, post: 418.4 ± 318.4 U/L; Placebo: pre:238 ± 94.03 U/L, post:486 ± 336.6 U/L) increased after protocol (p = 0.005), however, without differences between conditions. In conclusion, the NaHCO3 did not attribute benefits in performance or in parameters related to the internal load of exercise.

Comparison of total cold-water immersion's effects to ice massage on recovery from exercise-induced muscle damage

Purpose

The purpose of the study is to compare the effects of total cold-water immersion to ice massage on muscle damage, performance, and delayed onset of muscle soreness.

Methods

Sixty participants were randomized into two groups where they completed a muscle damage protocol. Afterward, muscle damage, muscle performance, and delayed onset muscle soreness were respectively measured by serum Creatine Kinase (CK) test, one-repetition maximum (1-RM) test, countermovement jump (CMJ) test, and visual analog scale (VAS). The measurements were taken at five different timelines (Baseline, 2 H, 24 H, 48 H, and 72 H).

Results

Data showed that values of all within-group measures of the dependent variables had extremely significant statistical differences (p < 0.001) for both intervention groups. Serum CK values peaked at 24 H for both groups. At 72 H, serum CK values dropped to baseline values in the total cold-water immersion group, while remaining high in the ice massage group. At 72 H, the values of the 1-RM test, CMJ test, and VAS approximated baseline values only in the total cold-water immersion group (p < 0.001).

Conclusions

Total cold-water immersion (TCWI) was more effective when compared to ice massage (IM) on improving values of recovery from exercise-induced muscle damage (EIMD). Hence, this modality may be considered during athletic recovery to maximize athletic performance.

Clinical trial registration

This trial was registered in ClinicalTrials.gov under the trial registration number (NCT04183816).

Acute Supplementation with Cannabidiol Does Not Attenuate Inflammation or Improve Measures of Performance following Strenuous Exercise

Supplementation with cannabidiol (CBD) may expedite recovery when consumed after exercise. The purpose of this study was to determine if supplementation with CBD reduces inflammation and enhances performance following strenuous eccentric exercise in collegiate athletes. Twenty-four well-trained females (age = 21.2 ± 1.8 years, height = 166.4 ± 8 cm, weight = 64.9 ± 9.1 kg) completed 100 repetitions of unilateral eccentric leg extension to induce muscle damage. In this crossover design, participants were randomized to receive 5 mg/kg of CBD in pill form or a placebo 2 h prior to, immediately following, and 10 h following muscle damage. Blood was collected, and performance and fatigue were measured prior to, and 4 h, 24 h, and 48 h following the muscle damage. Approximately 28 days separated treatment administration to control for the menstrual cycle. No significant differences were observed between the treatments for inflammation, muscle damage, or subjective fatigue. Peak torque at 60°/s (p = 0.001) and peak isometric torque (p = 0.02) were significantly lower 24 h following muscle damage, but no difference in performance was observed between treatments at any timepoint. Cannabidiol supplementation was unable to reduce fatigue, limit inflammation, or restore performance in well-trained female athletes.

Age Differences in Recovery Rate Following an Aerobic-Based Exercise Protocol Inducing Muscle Damage Among Amateur, Male Athletes

Purpose: Compare recovery rates between active young (Y) and middle-aged (MA) males up to 48H post aerobically based, exercise-induced muscle damage (EIMD) protocol. A secondary aim was to explore the relationships between changes in indices associated with EIMD and recovery throughout this timeframe.

Methods: Twenty-eight Y (n = 14, 26.1 ± 2.9y, 74.5 ± 9.3 kg) and MA (n = 14, 43.6 ± 4.1y, 77.3 ± 12.9 kg) physically active males, completed a 60-min downhill running (DHR) on a treadmill at −10% incline and at 65% of maximal heart rate (HR). Biochemical, biomechanical, psychological, force production and muscle integrity (using MRI diffusion tensor imaging) markers were measured at baseline, immediately-post, and up to 48H post DHR.

Results: During the DHR, HR was lower (p < 0.05) in MA compared to Y, but running pace and distance covered were comparable between groups. No statistical or meaningful differences were observed between groups for any of the outcomes. Yet, Significant (p < 0.05) time-effects within each group were observed: markers of muscle damage, cadence and perception of pain increased, while TNF-a, isometric and dynamic force production and stride-length decreased. Creatine-kinase at 24H-post and 48H-post were correlated (p < 0.05, r range = −0.57 to 0.55) with pain perception, stride-length, and cadence at 24H-post and 48H-post. Significant (p < 0.05) correlations were observed between isometric force production at all time-points and IL-6 at 48H-post DHR (r range = −0.62 to (−0.74).

Conclusion: Y and MA active male amateur athletes recover in a comparable manner following an EIMD downhill protocol. These results indicate that similar recovery strategies can be used by trainees from both age groups following an aerobic-based EIMD protocol.

The Influence of Phototherapy on Recovery From Exercise-Induced Muscle Damage

Background

Intense physical activity can result in exercise-induced muscle damage, delayed-onset muscle soreness, and decrements in performance. Phototherapy (PhT), sometimes referred to as photobiomodulation or low-level laser therapy, may enhance recovery from vigorous exercise.

Purpose

The purpose of this study was to assess the influence of phototherapy on functional movements (vertical jump, agility), and perceptions of muscle soreness following exercise-induced muscle damage caused by high volume sprinting and decelerations.

Methods

In a between-group design, 33 participants performed 40x15m sprints, a protocol intended to cause muscle damage. Immediately following sprinting and in the four days following, vertical jump and agility were assessed, as well as calf, hamstring, quadriceps, and overall perceptions of soreness. Sixteen subjects (age 20.6±1.6 yrs; BMI 25.8±4.6 kg.m-2) received PhT prior to testing each day, while 17 (age 20.8±1.3 yrs; BMI 26.2±4.5 kg.m-2) received sham PhT and served as a control (CON). Measurements were recorded during five days of recovery from the repeated sprint protocol, then compared to those recorded during three baseline days of familiarization. Area under the curve was calculated by summing all five scores, and comparing those values by condition via a two-tailed unpaired t-test for normally distributed data, and a two-tailed Mann-Whitney U test for nonparametric data (alpha level = 0.05).

Results

Calf soreness was lower in PhT compared to CON (p = 0.02), but no other significant differences were observed between groups for vertical jump, agility, quadriceps, hamstring, and overall soreness (p > 0.05).

Discussion

Phototherapy may attenuate soreness in some muscle groups following exercise-induced muscle damage, but may not enhance recovery after explosive, short-duration activities.

Conclusion

Phototherapy may not be a useful recovery tool for those participating in explosive, short-duration activities.

Level of evidence

2c.

Effects of the combination of vitamins C and E supplementation on oxidative stress, inflammation, muscle soreness, and muscle strength following acute physical exercise: meta-analyses of randomized controlled trials

Background:The combined supplementation of vitamins C and E potentially can mitigate oxidative stress (OS) and accelerate recovery following exercise. However, there is little evidence and a lack of consensus on the effects of these vitamins for this purpose. The objective of this systematic review was to summarize the evidence on the effects of the combined supplementation of vitamins C and E in OS, inflammatory markers, muscle damage, muscle soreness, and musculoskeletal functionality following acute exercise. Methods: The search was carried out from inception until March 2021, on MEDLINE, EMBASE, Cochrane CENTRAL, Web of Science, and SPORT Discus. We included placebo-controlled randomized clinical trials (RCTs) that evaluated the effects of combined supplementation of vitamins C and E in OS, inflammatory markers, muscle damage, muscle soreness, and muscle strength following a single bout of exercise. Random-effect meta-analyses were used to compare pre to post-exercise mean changes in subjects who received supplementation with vitamins C and E or placebo versus controls. Data are presented as standard mean difference (SMD) and 95% confidence interval (95% CI). Results: Eighteen RCTs, accounting for data from 322 individuals, were included. The use of vitamins attenuated lipid peroxidation (SMD= -0.703; 95% CI= -1.035 to -0.372; p < 0.001), IL-6 (SMD= -0.576; 95%CI= -1.036 to -0.117; p = 0.014), and cortisol levels (SMD= -0.918; 95%CI= -1.475 to -0.361; p = 0.001) immediately, and creatine kinase levels 48 h following exercise (SMD= -0.991; 95%CI= -1.611 to -0.372; p = 0.002). Supplementing the combination of vitamins had no effects on protein carbonyls, reduced/oxidized glutathione ratio, catalase, interleukin-1Ra, C-reactive protein, lactate dehydrogenase, muscle soreness, and muscle strength. Conclusion: Prior supplementation of the combination of vitamins C and E attenuates OS (lipid peroxidation), the inflammatory response (interleukin-6), cortisol levels, and muscle damage (creatine kinase) following a session of exercise.

Visualization of Human Skeletal Muscle Anisotropy by Using Dual-Direction Shear Wave Imaging

OBJECTIVE

Ultrasound (US) shear wave elasticity imaging (SWEI) is a mature technique for diagnosing the elasticity of isotropic tissues. However, the elasticity of anisotropic tissues, such as muscle and tendon, cannot be diagnosed correctly using SWEI because the shear wave velocity (SWV) varies with tissue fiber orientations. Recently, SWEI has been studied for measuring the anisotropic properties of muscles by rotating the transducer; however, this is difficult for clinical practice.

METHODS

In this study, a novel dual-direction shear wave imaging (DDSWI) technique was proposed for visualizing the mechanical anisotropy of muscles without rotation. Longitudinal and transverse shear waves were created by a specially designed external vibrator and supersonic pushing beam, respectively; the SWVs were then tracked using ultrafast US imaging. Subsequently, the SWV maps of two directions were obtained at the same scanning cross section, and the mechanical anisotropy was represented as the ratio between them at each pixel.

RESULTS

The performance of DDSWI was verified using a standard phantom, and human experiments were performed on the gastrocnemius and biceps brachii. Experimental results of phantom revealed DDSWI exhibited a high precision of <0.81 % and a low bias of <3.88 % in SWV measurements. The distribution of anisotropic properties in muscle was visualized with the anisotropic ratios of 1.54 and 2.27 for the gastrocnemius and biceps brachii, respectively.

CONCLUSION

The results highlight the potential of this novel anisotropic imaging in clinical applications because the conditions of musculoskeletal fiber orientation can be easily and accurately evaluated in real time by DDSWI.

Highly Cushioned Shoes Improve Running Performance in Both the Absence and Presence of Muscle Damage

PURPOSE

We tested the hypotheses that a highly cushioned running shoe (HCS) would: 1) improve incremental exercise performance and reduce the oxygen cost (Oc) of submaximal running; and 2) attenuate the deterioration in Oc elicited by muscle damage consequent to a downhill run.

METHODS

Thirty-two recreationally-active participants completed an incremental treadmill test in a HCS and a control running shoe (CON) for the determination of Oc and maximal performance. Subsequently, participants were pair-matched and randomly assigned to one of the two footwear conditions to perform a moderate-intensity running bout pre- and 48 h post a 30-min downhill run designed to elicit muscle damage.

RESULTS

Incremental treadmill test performance was improved (+5.7%; +1:16 min:ss; P < 0.01) in the HCS when assessed in the non-damaged state, relative to CON. This coincided with a significantly lower Oc (-3.2%; -6 ml·kg-1·km-1; P < 0.001) at a range of running speeds and an increase in the speed corresponding to 3 mM blood lactate (+3.2%; +0.4 km·h-1; P < 0.05). As anticipated, the downhill run resulted in significant changes in biochemical, histological, and perceptual markers of muscle damage, and a significant increase in Oc (+5.2%; 10.1 ml·kg-1·km-1) was observed 48 h post. In the presence of muscle damage, Oc was significantly lower in HCS (-4.6%; -10 ml·kg-1·km-1) compared to CON.

CONCLUSIONS

These results indicate that HCS improved incremental exercise performance and Oc in the absence of muscle damage and show, for the first time, that despite worsening of Oc consequent to muscle damage, improved Oc in HCS is maintained.

Thirty minutes of moderate-intensity downhill or level running has no effect on postprandial lipemia: A randomized controlled trial

Elevated postprandial triglyceride (TG) concentrations are linked to a relatively high risk of cardiovascular disease. Eccentric endurance exercise, such as downhill walking and running, can provide metabolic benefits similar to concentric exercise. However, whether eccentric exercise affects postprandial lipemia remains unknown. Nine healthy young men performed level running (trial) or downhill running (DR trial, -15% slope) at 60% [INSIDE:1]O_2max or rest (CON trial) for 30 min in a randomized crossover design. The participants were fed a high-fat meal the next day. Blood and expired gas samples were collected before and 0.5, 1, 2, 3, 4, 5, and 6 h after the meal. Muscle soreness was measured using a visual analog scale. The DR trial induced mild muscle damage. During the 6-h postprandial period, serum TG concentrations and area under the curve (AUC) were similar across the three trials. The DR trial had a significantly higher AUC of nonesterified fatty acid concentrations and a significantly lower AUC of glucose concentrations than the CON trial. The results suggested that neither moderate-intensity DR nor running a level surface had a significant effect on lipemia after a high-fat meal. However, DR improved the postprandial glycemic response.

Effects of Curcumin Supplementation on Inflammatory Markers, Muscle Damage, and Sports Performance during Acute Physical Exercise in Sedentary Individuals

Exhaustive and acute unusual physical exercise leads to muscle damage. Curcumin has been widely studied due to the variety of its biological activities, attributed to its antioxidant and anti-inflammatory properties. Furthermore, it has shown positive effects on physical exercise practitioners. However, there is no literature consensus on the beneficial effects of curcumin in acute physical activities performed by sedentary individuals. Therefore, we systematically reviewed evidence from clinical trials on the main effects of curcumin supplementation on inflammatory markers, sports performance, and muscle damage during acute physical exercises in these individuals. We searched PubMed/MEDLINE, Scopus, Web of Science, and Embase databases, and only original studies were analyzed according to the PRISMA guidelines. The included studies were limited to supplementation of curcumin during acute exercise. A total of 5 studies were selected. Methodological quality assessments were examined using the SYRCLE's risk-of-bias tool. Most studies have shown positive effects of curcumin supplementation in sedentary individuals undergoing acute physical exercise. Overall, participants supplemented with curcumin showed less muscle damage, reduced inflammation, and better muscle performance. The studies showed heterogeneous data and exhibited methodological limitations; therefore, further research is necessary to ensure curcumin supplementation benefits during acute and high-intensity physical exercises. Additionally, mechanistic and highly controlled studies are required to improve the quality of the evidence and to elucidate other possible mechanisms. This study is registered with Prospero number CRD42021262718.

Optimizing the Explosive Force of the Elite Level Football-Tennis Players through Plyometric and Specific Exercises

The aim of the research was to implement an athletic program to improve the explosive force in order to optimize physical fitness at the level of elite football-tennis players and evaluate the progress made through specific tests using the Opto Jump. The research included 10 elite European and world-class players, on whom an experimental program was applied in order to improve the explosive force of the limbs in conditions of speed, endurance, and dynamic balance. Study tests: five vertical jumps on the spot, on the left/right leg; five back and forth jumps on the left/right leg; five left/right side jumps on the left/right leg; vertical jumps on both legs 60 s; BFS vertical jumps. For each test, the following parameters specific to the explosive force were statistically analyzed: contact time (s); flight time (s); jump height (cm), jump power (w/kg); RSI—Reactive Strength Index, defined as Height (m/s). In the study, the average value of the parameters specific to the jumps performed in each test was taken into account. During the study, the tests were performed and processed on the Opto Jump device and software. In all tests of the experiment monitored through Opto Jump, significant progress was made in the final test compared to the initial one, which demonstrates the efficiency of the physical training program implemented for the development of explosive force, with an impact on the sports performance of elite players. The most relevant results obtained for the left leg regarding the improvement of the explosive force of the lower limbs materialized in the jump height parameter was in the test of five vertical jumps on one leg on the spot, and for the right leg in the tests of: five back and forth jumps and five left/right side jumps. The most significant advances in the study were in the tests, in descending order of their weight: 60 s vertical jumps on both legs; five back-and-forth jumps and five left/right side jumps, five vertical jumps on one leg standing, and BFS vertical jumps.

The effect of active vs passive recovery and use of compression garments following a single bout of muscle-damaging exercise

BACKGROUND: Some recovery strategies are needed to reduce or eliminate the effect of negative symptoms caused by exercise. OBJECTIVE: The aim of this study was to determine the effect of different types of recovery after single-bout strength exercises on biomarkers of muscle damage, cytokine release and lactate elimination. METHODS: Following familiarization, 10 male volunteers performed four randomized recovery protocols (passive or active recovery with or without compression garments) following a single bout of resistance exercise (squat and deadlift exercises). The blood creatine kinase (CK), lactate dehydrogenase (LDH), interleukine-6 (IL-6), and tumor necrosis factor-alfa (TNF-α) values were measured before and after exercise, and after 24, 48, 72 hours. RESULTS: The CK analysis showed that all protocols significantly increased (p< 0.05) CK activity compared to the pre and 24 h post time points. Interestingly, protocol 3 and 4 significantly decreased (p< 0.05) CK activity compared 24 and 72 h post-exercise. LDH, IL-6, and TNF values did not show significant difference (p> 0.05) at the time points tested. CONCLUSIONS: Active recovery is an effective method for reducing the severity and duration of muscle damage and for accelerating the clearance of blood lactate (BLa) following a single bout of strength training. There is no added benefit of using compression garments.

Peak week recommendations for bodybuilders: an evidence based approach

Bodybuilding is a competitive endeavor where a combination of muscle size, symmetry, "conditioning" (low body fat levels), and stage presentation are judged. Success in bodybuilding requires that competitors achieve their peak physique during the day of competition. To this end, competitors have been reported to employ various peaking interventions during the final days leading to competition. Commonly reported peaking strategies include altering exercise and nutritional regimens, including manipulation of macronutrient, water, and electrolyte intake, as well as consumption of various dietary supplements. The primary goals for these interventions are to maximize muscle glycogen content, minimize subcutaneous water, and reduce the risk abdominal bloating to bring about a more aesthetically pleasing physique. Unfortunately, there is a dearth of evidence to support the commonly reported practices employed by bodybuilders during peak week. Hence, the purpose of this article is to critically review the current literature as to the scientific support for pre-contest peaking protocols most commonly employed by bodybuilders and provide evidence-based recommendations as safe and effective strategies on the topic.

Recommendations for Plyometric Training after ACL Reconstruction - A Clinical Commentary

This paper presents a four-stage plyometric program to be undertaken as part of criterion-based rehabilitation for athletes with anterior cruciate ligament reconstruction (ACLR). After ACLR, the patient experiences alterations of joint mobility, gait and movement patterns, neuromuscular function and general physical fitness. Plyometric training is an important component for neuromuscular and movement re-conditioning after ACLR. Effective use of plyometrics can support enhancements in explosive sporting performance, movement quality and lower risk of injury. Plyometric training, as a component of the ACL functional recovery process, can aid in restoring function and supporting timely return to sport. However, few patients undertake or complete a plyometric program prior to return-to-sport. To truly impact individual patients, a stronger focus on research implementation is needed from researchers to translate efficacious interventions into practice. In designing a plyometric program, it is important to match the specific plyometric tasks to the functional recovery status of the ACLR patient. To do this, it is important to understand the relative intensity of plyometrics tasks, align these tasks to the ACL functional recovery process and monitor the athlete as part of criterion based rehabilitation. Plyometric intensity is based on the intensity of efforts, the vertical and/or horizontal momentum prior to ground contact, the ground contact time and the surface or environment on which they are performed on/in. Furthermore, how the person technically performs the task will influence joint loading. There should be a gradual increase in task intensity and specificity throughout the program, with all tasks used for both neuromuscular and motor control re-conditioning. The aim of this paper is to provide recommendations to clinicians on how to design and implement plyometric training programs for the ACLR patient, as part of the functional recovery process.

LEVEL OF EVIDENCE

5.

Effects of Kinesio Tape on Delayed Onset Muscle Soreness: A Systematic Review and Meta-analysis

Background

Kinesio tape (KT) may be useful for the treatment of delayed onset muscle soreness (DOMS), but there has been no systematic review assessing their efficacy.

Objectives

We conducted a systematic review and meta-analysis to evaluate the efficacy of KT on DOMS.

Methods

We searched seven databases for randomized controlled trials (RCTs) and crossover randomized trials of KT in DOMS, from the earliest date available to December 31, 2019. The primary outcome was muscle soreness. The secondary outcome was muscle strength and serum creatine kinase (CK) level. The risk of bias was evaluated based on the Cochrane criteria. Data were analyzed using RevMan version 5.3.0 software. P values < 0.05 were considered statistically significant. Systematic review registration number is CRD42020157052.

Results

Eight trials (six RCTs and two crossover randomized trials) with 289 participants were included. KT use significantly reduced muscle soreness at 48 h (mean difference (MD): -0.67, 95% confidence interval (CI): -1.10 to 0.24, P = 0.002) and 72 h postexercise (MD: -0.81, 95% CI: -1.45 to -0.17, P = 0.01) but not at 24 h. KT use improved muscle strength at 72 h postexercise (standardized mean difference: 0.35, 95% CI: 0.02 to 0.69, P = 0.04) but not at 24 or 48 h. However, the serum CK level at 24, 48, and 72 h postexercise was not better in the KT group relative to the control group.

Conclusions

Current evidence suggests that KT might help to alleviate DOMS after strenuous exercise to improve muscle strength. Thus, using KT on the skin for more than 48 hours postexercise, but not for 24 h, appears more effective at relieving pain and improving muscle strength.

The cold truth: the role of cryotherapy in the treatment of injury and recovery from exercise

Cryotherapy is utilized as a physical intervention in the treatment of injury and exercise recovery. Traditionally, ice is used in the treatment of musculoskeletal injury while cold water immersion or whole-body cryotherapy is used for recovery from exercise. In humans, the primary benefit of traditional cryotherapy is reduced pain following injury or soreness following exercise. Cryotherapy-induced reductions in metabolism, inflammation, and tissue damage have been demonstrated in animal models of muscle injury; however, comparable evidence in humans is lacking. This absence is likely due to the inadequate duration of application of traditional cryotherapy modalities. Traditional cryotherapy application must be repeated to overcome this limitation. Recently, the novel application of cooling with 15 °C phase change material (PCM), has been administered for 3-6 h with success following exercise. Although evidence suggests that chronic use of cryotherapy during resistance training blunts the anabolic training effect, recovery using PCM does not compromise acute adaptation. Therefore, following exercise, cryotherapy is indicated when rapid recovery is required between exercise bouts, as opposed to after routine training. Ultimately, the effectiveness of cryotherapy as a recovery modality is dependent upon its ability to maintain a reduction in muscle temperature and on the timing of treatment with respect to when the injury occurred, or the exercise ceased. Therefore, to limit the proliferation of secondary tissue damage that occurs in the hours after an injury or a strenuous exercise bout, it is imperative that cryotherapy be applied in abundance within the first few hours of structural damage.

Effect of Boards in Small-Sided Street Soccer Games on Movement Pattern and Physiological Response in Recreationally Active Young Men

Randers, MB, Brix, J, Hagman, M, Nielsen, JJ, and Krustrup, P. Effect of boards in small-sided street soccer games on movement pattern and physiological response in recreationally active young men. J Strength Cond Res 34(12): 3530-3537, 2020-This study investigated whether street soccer might be proposed as an alternative to recreational small-sided games on grass as a health-enhancing activity and, specifically, the effects of the boards surrounding the pitch. Eleven recreationally active young men (28.4 ± 4.2 SD years, 19.9 ± 4.2% body fat, and 47.7 ± 6.0 ml·min·kg), after familiarization, completed one to 2 sessions of 20 × 13-m 3v3 street soccer games with boards (WBs) and one to 2 sessions without boards (WOBs) in a randomized order. Movement pattern was measured using global positioning system, and heart rate recordings, blood sampling, and rating of perceived exertion (RPE) scales were used to evaluate exercise intensity and physiological strain. Total number of accelerations (19%) and player load (18%) were higher (p ≤ 0.005) in WB than in WOB, whereas total distance covered (12%), high-speed running (59%), and peak speed (11%) were lower (p ≤ 0.003) in WB than in WOB. Moreover, HRmean was higher in WB than in WOB (85.7 ± 5.4 vs. 81.3 ± 8.2% HRmax, p = 0.012, ES = 0.64), whereas time with HR > 90% HRmax did not differ between WB and WOB (42 ± 34 vs. 32 ± 30%, p = 0.243, ES = 0.32). Plasma ammonia increased more in WB than in WOB, with no differences found in mean and peak blood lactate. Rating of perceived exertion was higher after WB than after WOB (7.1 ± 1.0 vs. 5.5 ± 1.2, p < 0.001, ES = 1.39). In conclusion, intensity was sufficiently high in both game formats to expect short- and long-term health improvements as a result of regular participation. Boards affected movement pattern and physiological demands, producing higher number of accelerations, player load, average heart rate, plasma ammonia, and RPE but lower total distance, number of intense runs, and peak speed.

Resistance Training Affects Neuromuscular Fatigue But Not Efficiency in Elite Rowers

PURPOSE

To investigate how resistance training (RT) in a regular training program affects neuromuscular fatigue (NMF) and gross efficiency (EGROSS) in elite rowers.

METHODS

Twenty-six elite male rowers performed 4 RT sessions within 10 days. At baseline and after the first and fourth RT, EGROSS and NMF were established. From breathing gas, EGROSS was determined during submaximal rowing tests. Using a countermovement jump test, NMF was assessed by jump height, flight time, flight-to-contraction-time ratio, peak power, and time to peak power. Muscle soreness was assessed using a 10-cm-long visual analog scale.

RESULTS

No significant differences were found for EGROSS (P = .565, ω2 = .032). Muscle soreness (P = .00, ω2 = .500) and time to peak power (P = .08, ω2 = 0.238) were higher compared with baseline at all test moments. Flight-to-contraction-time ratio, jump height, and peak power after the fourth RT differed from baseline (P < .05, ω2 = .36, ω2 = .38, and ω2 = .31) and from results obtained after the first RT (P < .05, ω2 = .36, ω2 = .47, and ω2 = .22).

CONCLUSIONS

RT in general does not influence EGROSS, but large individual differences (4.1%-14.8%) were observed. NMF is affected by RT, particularly after multiple sessions. During periods of intensified RT, imposed external load for low-intensity endurance training need not be altered, but rowers are recommended to abstain from intensive endurance training. Individual monitoring is strongly recommended.

The Effects of Age and Body Fat Content on Post-Downhill Run Recovery Following Whole Body Cryotherapy

This study explored the effects of age and body fat content on responses to whole body cryotherapy (WBC) following a downhill running bout. Forty-one male participants (mean ± SD age 42.0 ± 13.7 years, body mass 75.2 ± 10.8 kg) were allocated into WBC (n = 26) and control (CON, n = 15) groups. WBC participants were divided into old (OLD, ≥45 years, n = 10) and young (YNG, <40 years, n = 13), as well as high fat (HFAT, ≥20%, n = 10) and low fat (LFAT ≤ 15%, n = 8) groups. Participants completed a 30 min downhill run (15% gradient) at 60% VO2 max. The WBC group underwent cryotherapy (3 min, -120 °C) 1 h post-run and CON participants passively recovered in a controlled environment (20 °C). Maximal isometric leg muscle torque was assessed pre and 24 h post-run. Blood creatine kinase (CK) and muscle soreness were assessed pre, post, one hour and 24 h post-run. Muscle torque significantly decreased in both groups post-downhill run (WBC: 220.6 ± 61.4 Nm vs. 208.3 ± 67.6 Nm, p = 0.02; CON: 239.7 ± 51.1 Nm vs. 212.1 ± 46.3 Nm, p = 0.00). The mean decrease in WBC was significantly less than in CON (p = 0.04). Soreness and CK increased 24 h post for WBC and CON (p < 0.01) with no difference between groups. Muscle torque significantly decreased in OLD participants (p = 0.04) but not in YNG (p = 0.55). There were no differences between HFAT and LFAT (all p values > 0.05). WBC may attenuate muscle damage and benefit muscle strength recovery following eccentrically biased exercises, particularly for young males.

Exercise-induced muscle damage: mechanism, assessment and nutritional factors to accelerate recovery

There have been a multitude of reviews written on exercise-induced muscle damage (EIMD) and recovery. EIMD is a complex area of study as there are a host of factors such as sex, age, nutrition, fitness level, genetics and familiarity with exercise task, which influence the magnitude of performance decrement and the time course of recovery following EIMD. In addition, many reviews on recovery from exercise have ranged from the impact of nutritional strategies and recovery modalities, to complex mechanistic examination of various immune and endocrine signaling molecules. No one review can adequately address this broad array of study. Thus, in this present review, we aim to examine EIMD emanating from both endurance exercise and resistance exercise training in recreational and competitive athletes and shed light on nutritional strategies that can enhance and accelerate recovery following EIMD. In addition, the evaluation of EIMD and recovery from exercise is often complicated and conclusions often depend of the specific mode of assessment. As such, the focus of this review is also directed at the available techniques used to assess EIMD.

Can Exercise-Induced Muscle Damage Be a Good Model for the Investigation of the Anti-Inflammatory Properties of Diet in Humans?

Subclinical, low-grade, inflammation is one of the main pathophysiological mechanisms underlying the majority of chronic and non-communicable diseases. Several methodological approaches have been applied for the assessment of the anti-inflammatory properties of nutrition, however, their impact in human body remains uncertain, because of the fact that the majority of the studies reporting anti-inflammatory effect of dietary patterns, have been performed under laboratory settings and/or in animal models. Thus, the extrapolation of these results to humans is risky. It is therefore obvious that the development of an inflammatory model in humans, by which we could induce inflammatory responses to humans in a regulated, specific, and non-harmful way, could greatly facilitate the estimation of the anti-inflammatory properties of diet in a more physiological way and mechanistically relevant way. We believe that exercise-induced muscle damage (EIMD) could serve as such a model, either in studies investigating the homeostatic responses of individuals under inflammatory stimuli or for the estimation of the anti-inflammatory or pro-inflammatory potential of dietary patterns, foods, supplements, nutrients, or phytochemicals. Thus, in this review we discuss the possibility of exercise-induced muscle damage being an inflammation model suitable for the assessment of the anti-inflammatory properties of diet in humans.

Don't Lose Your Cool With Cryotherapy: The Application of Phase Change Material for Prolonged Cooling in Athletic Recovery and Beyond

Strenuous exercise can result in muscle damage in both recreational and elite athletes, and is accompanied by strength loss, and increases in soreness, oxidative stress, and inflammation. If the aforementioned signs and symptoms associated with exercise-induced muscle damage are excessive or unabated, the recovery process becomes prolonged and can result in performance decrements; consequently, there has been a great deal of research focussing on accelerating recovery following exercise. A popular recovery modality is cryotherapy which results in a reduction of tissue temperature by the withdrawal of heat from the body. Cryotherapy is advantageous because of its ability to reduce tissue temperature at the site of muscle damage. However, there are logistical limitations to traditional cryotherapy modalities, such as cold-water immersion or whole-body cryotherapy, because they are limited by the duration for which they can be administered in a single dose. Phase change material (PCM) at a temperature of 15°C can deliver a single dose of cooling for a prolonged duration in a practical, efficacious, and safe way; hence overcoming the limitations of traditional cryotherapy modalities. Recently, 15°C PCM has been locally administered following isolated eccentric exercise, a soccer match, and baseball pitching, for durations of 3-6 h with no adverse effects. These data showed that using 15°C PCM to prolong the duration of cooling successfully reduced strength loss and soreness following exercise. Extending the positive effects associated with cryotherapy by prolonging the duration of cooling can enhance recovery following exercise and give athletes a competitive advantage.

Prolonging the duration of cooling does not enhance recovery following a marathon

Runners commonly utilize cryotherapy as part of their recovery strategy. Cryotherapy has been ineffective in mitigating signs and symptoms of muscle damage following marathon running and is limited by its duration of application. Phase change material (PCM) packs can prolong the duration of cooling. This study aimed to test the efficacy of prolonging the duration of cooling using PCM on perceptual recovery, neuromuscular function, and blood markers following a marathon run. Thirty participants completed a marathon run and were randomized to receive three hours of 15°C PCM treatment covering the quadriceps or recover without an intervention (control). Quadriceps soreness, strength, countermovement jump (CMJ) height, creatine kinase (CK), and high sensitivity C-reactive protein (hsCRP) were recorded at baseline, 24, 48, and 72 hours after the marathon. Following the marathon, strength decreased in both groups (P < .0001), with no difference between groups. Compared to baseline, strength was reduced 24 (P = .004) and 48 hours after the marathon (P = .008) in the control group, but only 24 hours (P = .028) in the PCM group. Soreness increased (P < .0001) and CMJ height decreased (P < .0001) in both groups, with no difference between groups. Compared to baseline, CMJ height was not reduced on any days in the PCM group but was reduced in the control group 24 (P < .0001) and 48 hours (P = .003) after the marathon. CK and hsCRP increased in both groups (P < .0001). Although the marathon run induced significant muscle damage, prolonging the duration of cooling using PCM did not accelerate the resolution of any dependent variables.

Pathophysiology of exercise-induced muscle damage and its structural, functional, metabolic, and clinical consequences

Extreme or unaccustomed eccentric exercise can cause exercise-induced muscle damage, characterized by structural changes involving sarcomere, cytoskeletal, and membrane damage, with an increased permeability of sarcolemma for proteins. From a functional point of view, disrupted force transmission, altered calcium homeostasis, disruption of excitation-contraction coupling, as well as metabolic changes bring about loss of strength. Importantly, the trauma also invokes an inflammatory response and clinically presents itself by swelling, decreased range of motion, increased passive tension, soreness, and a transient decrease in insulin sensitivity. While being damaging and influencing heavily the ability to perform repeated bouts of exercise, changes produced by exercise-induced muscle damage seem to play a crucial role in myofibrillar adaptation. Additionally, eccentric exercise yields greater hypertrophy than isometric or concentric contractions and requires less in terms of metabolic energy and cardiovascular stress, making it especially suitable for the elderly and people with chronic diseases. This review focuses on our current knowledge of the mechanisms underlying exercise-induced muscle damage, their dependence on genetic background, as well as their consequences at the structural, functional, metabolic, and clinical level. A comprehensive understanding of these is a prerequisite for proper inclusion of eccentric training in health promotion, rehabilitation, and performance enhancement.

Local Heat Therapy to Accelerate Recovery After Exercise-Induced Muscle Damage

The prolonged impairment in muscle strength, power, and fatigue resistance after eccentric exercise has been ascribed to a plethora of mechanisms, including delayed muscle refueling and microvascular and mitochondrial dysfunction. This review explores the hypothesis that local heat therapy hastens functional recovery after strenuous eccentric exercise by facilitating glycogen resynthesis, reversing vascular derangements, augmenting mitochondrial function, and stimulating muscle protein synthesis.

Effects of Pre-Sleep Whey vs. Plant-Based Protein Consumption on Muscle Recovery Following Damaging Morning Exercise

Pre-sleep whey protein intake has been shown to improve overnight muscle protein synthesis, muscle size and strength, and muscle recovery. Despite a growing interest in alternative protein sources, such as plant-based protein, there is no evidence regarding the efficacy of plant-based proteins consumed pre-sleep. Therefore, we aimed to compare whey vs. plant-based pre-sleep protein dietary supplementation on muscle recovery in middle-aged men. Twenty-seven recreationally active, middle-aged men performed 5 sets of 15 repetitions of maximal eccentric voluntary contractions (ECC) for the knee extensors (ext) and flexors (flex), respectively, in the morning. Participants consumed 40 g of either whey hydrolysate (WH, n = 9), whey isolate (WI, n = 6), rice and pea combination (RP, n = 6), or placebo (PL, n = 6) 30 min pre-sleep on the day of ECC and the following two nights. Catered meals (15% PRO, 55% CHO, 30% Fat) were provided to participants for 5 days to standardize nutrition. Plasma creatine kinase (CK), interleukin-6 (IL-6), and interleukin-10 (IL-10) were measured at pre, immediately post (+0), +4, +6, +24, +48, and +72 h post-ECC. Isometric (ISOM) and isokinetic (ISOK) maximal voluntary contraction force were measured at pre, immediately post (+0), +24, +48, and +72 h post-ECC. Muscle soreness, thigh circumference, and HOMA-IR were measured at pre, +24, +48, and +72 h post-ECC. CK was increased at +4 h post-ECC, remained elevated at all time points compared to baseline (p < 0.001), and was significantly greater at +72 h compared to all other time points (p < 0.001). IL-6 was increased at +6 h (p = 0.002) with no other time differing from baseline. ISOMext was reduced after ECC (p = 0.001) and remained reduced until returning to baseline at +72 h. ISOMflex, ISOKext, and ISOKflex were reduced after ECC and remained reduced at +72 h (p < 0.001). Muscle soreness increased post-ECC (p < 0.001) and did not return to baseline. Thigh circumference (p = 0.456) and HOMA-IR (p = 0.396) did not change post-ECC. There were no significant differences between groups for any outcome measure. These data suggest that middle-aged men consuming 1.08 ± 0.02 g/kg/day PRO did not recover from damaging eccentric exercise at +72 h and that pre-sleep protein ingestion, regardless of protein source, did not aid in muscle recovery when damaging eccentric exercise was performed in the morning.

Effects of 120 g/h of Carbohydrates Intake during a Mountain Marathon on Exercise-Induced Muscle Damage in Elite Runners

Background-exercise-induced muscle damage (EIMD) and internal exercise load are increased after competing in ultraendurance events such as mountain marathons. Adequate carbohydrate (CHO) intake during exercise optimizes athletic performance and could limit EIMD, reduce internal exercise load and, thus, improve recovery. Therefore, the aim of this study was to research into and compare the effects of high CHO intake (120 g/h) in terms of CHO intake recommendation (90 g/h) and regular CHO intake performed by ultraendurance athletes (60 g/h) during a mountain marathon, on exercise load and EIMD markers (creatine kinase (CK), lactate dehydrogenase (LDH), glutamic oxaloacetic transaminase (GOT), urea and creatinine). Materials and Methods-a randomized trial was carried out on 20 male elite runners who had previously undertaken nutritional and gut training, and who consumed different CHO dosages according to experimental (EXP-120 g/h), control (CON-90 g/h) and low CHO intake (LOW-60 g/h) groups during a ~4000 m cumulative slope mountain marathon. EIMD markers were analyzed before the race and 24 h afterwards. Internal exercise load was calculated based on rate of perceived exertion (RPE) during and after the marathon event. Results-internal exercise load during the mountain marathon was significantly lower (p = 0.019; η2p = 0.471) in EXP (3805 ± 281 AU) compared to LOW (4688 ± 705 AU) and CON (4692 ± 716 AU). Moreover, results revealed that the EXP group evidenced significantly lower CK (p = 0.019; η2p = 0.373), LDH (p < 0.001; η2p = 0.615) and GOT (p = 0.003; η2p = 0.500) values 24 h after the mountain marathon race compared to LOW and CON. Along these lines, EIMD and exercise load evidenced a close correlation (R = 0.742; p < 0.001). Conclusion: High CHO intake (120 g/h) during a mountain marathon could limit the EIMD observed by CK, LDH and GOT and internal exercise load compared to CHO ingestion of 60 and 90 g/h.

Regulation of Circulatory Muscle-specific MicroRNA during 8 km Run

Acute prolonged endurance running has been shown to alter muscle-specific circulating microRNA (miRNA) levels. Here, eighteen participants completed an 8 km run. We assessed the levels of hsa-miR-1-3p, -133a-3p, -133b, and -206 and their correlation with conventional biomarkers following exercise. Compared to before exercise (Pre), 8 km run significantly increased the lactate level immediately after exercise (0 h). Myoglobin (Mb) level increased at 0 h while creatine kinase (CK) level increased 24 h after exercise (24 h). The levels of creatine kinase MB isoenzyme (CK-MB) and cardiac troponin I (cTnI) were all elevated at 24 h and within the normal physiological range; The levels of hsa-miR-1-3p, -133a-3p, -133b significantly increased at 0 h but only hsa-miR-133a-3p still elevated at 24 h. Only hsa-miR-206 level decreased at 24 h; Additionally, the changes of hsa-miR-1-3p and hsa-miR-133a-3p were correlated with Mb at 24 h. These findings suggest that muscle-specific miRNA elevation in plasma is likely physiological and that these miRNA may be used as potential biomarkers for load monitoring in individuals.