Serum Enzyme Monitoring in Sports Medicine

Effects of acai supplementation (Euterpe precatoria Mart) on muscle recovery markers after jump protocol

The objective was to evaluate the effects of acai supplementation (AS) on markers of muscle damage. Twelve men participated in the 21-day study. All performed the damage protocol (DP) in two moments, separated by 7 days. The DP consisted of 10 sets of 10 CMJs, with a recovery of 1 min between sets. The AS was performed for 7 days with 40 g/day of dehydrated acai (GA) or placebo (GP). Blood parameters (CK, LDH and Trolox-equivalent antioxidant capacity - TEAC) were evaluated at 0 h and 24 h. Ultrasound images (VL, RF and GM), DOMS in lower limbs and isometric peak torque (IPT) of knee extensors and flexors were evaluated at 0 h, 24 h, 48 h and 72 h after DP. A time-treatment interaction was observed for TEAC (p = 0.01), in which the GA presented increases of 11% after 24 h. Similarly, time-treatment interaction was observed for knee flexors IPT (p = 0.02), where GA showed superior recovery after 24 h (GA = 108 ± 23 vs. GP = 92 ± 24 N∙m) and 72 h (GA = 113 ± 31 vs. GP = 98 ± 26 N∙m). No significance was observed in the fatigue index for knee extensors (p = 0.75) and flexors (p = 0.89), indicating similar fatigue in both situations. We concluded that AS increased the TEAC and promoted faster recovery of the knee flexors IPT when compared to GP.

Study on Anti-Inflammatory Effects of and Muscle Recovery Associated with Transdermal Delivery of Chaenomeles speciosa Extracts Using Supersonic Atomizer on Rat Model

Repetitive motion or exercise is associated with oxidative stress and muscle inflammation, which can lead to declining grip strength and muscle damage. Oleanolic acid and ursolic acid have anti-inflammatory and antioxidant properties and can be extracted from Chaenomeles speciosa through ultrasonic sonication. We investigated the association between grip strength declines and muscle damage induced by lambda carrageenan (LC) injection and exercise exposure in rats. We also assessed the reparative effects of transdermal pretreatment and post-treatment with C. speciosa extracts (CSEs) by using a supersonic atomizer. The half-maximal inhibitory concentration (IC50) of CSEs for cells was 10.5 mg/mL. CSEs significantly reduced the generation of reactive oxygen species and inflammatory factors (interleukin [IL]-6 and IL-1β) in in vitro cell tests. Rats subjected to LC injection and 6 weeks of exercise exhibited significantly increased inflammatory cytokine levels (IL-1β, TNF-α, and IL-6). Hematoxylin and eosin staining revealed inflammatory cell infiltration and evident muscle damage in the gastrocnemius muscle, which exhibited splitting and the appearance of the endomysium and perimysium. The treated rats' grip strength significantly declined. Following treatment with CSEs, the damaged muscles exhibited decreased IL-1β, TNF-α, and IL-6 levels and normal morphologies. Moreover, grip strength significantly recovered. Pretreatment with CSEs yielded an immediate and significant increase in grip strength, with an increase of 180% and 165% occurring in the rats exposed to LC injection and exercise within the initial 12 h period, respectively, compared with the control group. Pretreatment with CSEs delivered transdermally using a supersonic atomizer may have applications in sports medicine and training or competitions.

The Influence of a Polyphenol-Rich Red Berry Fruit Juice on Recovery Process and Leg Strength Capacity after Six Days of Intensive Endurance Exercise in Recreational Endurance Athletes

BACKGROUND

Various nutritional strategies are increasingly used in sports to reduce oxidative stress and promote recovery. Chokeberry is rich in polyphenols and can reduce oxidative stress. Consequently, chokeberry juices and mixed juices with chokeberry content are increasingly used in sports. However, the data are very limited. Therefore, this study investigates the effects of the short-term supplementation of a red fruit juice drink with chokeberry content or a placebo on muscle damage, oxidative status, and leg strength during a six-day intense endurance protocol.

METHODS

Eighteen recreational endurance athletes participated in a cross-over high intensity interval training (HIIT) design, receiving either juice or a placebo. Baseline and post-exercise assessments included blood samples, anthropometric data, and leg strength measurements.

RESULTS

A significant increase was measured in muscle damage following the endurance protocol in all participants (∆ CK juice: 117.12 ± 191.75 U/L, ∆ CK placebo: 164.35 ± 267.00 U/L; p = 0.001, η2 = 0.17). No group effects were detected in exercise-induced muscle damage (p = 0.371, η2 = 0.010) and oxidative status (p = 0.632, η2 = 0.000). The reduction in strength was stronger in the placebo group, but group effects are missing statistical significance (∆ e1RM juice: 1.34 ± 9.26 kg, ∆ e1RM placebo: -3.33 ± 11.49 kg; p = 0.988, η2 = 0.000).

CONCLUSION

Although a reduction in strength can be interpreted for the placebo treatment, no statistically significant influence of chokeberry could be determined. It appears that potential effects may only occur with prolonged application and a higher content of polyphenols, but further research is needed to confirm this.

Effects of photobiomodulation applied at different times on functional performance and ergogenic response of rugby athletes: Randomized clinical trial

BACKGROUND

Photobiomodulation (PBM) is indicated to accelerate the recovery of athletes and reduce muscle damage caused by physical exercise. The objective of this study was to establish the best time to apply photobiomodulation to increase the functional performance and ergogenic response of rugby athletes.

METHODS

Randomized crossover clinical trial with 18 rugby athletes of both sexes. The interventions were carried out from January to May 2019. The blood levels of creatine kinase (CK) and lactate, and performance in the Modified Star Excursion Balance Test, Single Hop Test, Triple Hop Test, Bangsbo Sprint test (BST), and Yo-Yo intermittent recovery level 1 (YoyoIR1) were evaluated. The athletes underwent two blocks of exercises with the BST and Yoyo-IR1, as well as the random application of four interventions: without application of photobiomodulation (CO), pre-exercise photobiomodulation (PBpre), PBM during the exercise interval (PBint), or post-exercise photobiomodulation (PBpos). The photobiomodulation using light-emitting diodes (850 nm, 8 J/cm2) lasted 10 min and was applied to the quadriceps, hamstrings, and triceps surae muscles. The results were compared between groups and times, and the effect size for the interventions was established.

RESULTS

No differences were found between groups in CK, lactate, and performance in the functional tests between groups and times. Only the PBpre presented improved performance in the first Yoyo-1R1 test (p < 0.01), while the PBint improved in the second Yoyo-IR1 test and BST (p < 0.05).

CONCLUSION

The PBM did not change muscle damage markers or performance in the functional tests. For an ergogenic response, photobiomodulation applied before exercise improves performance, which can be maintained when PBM is performed in the exercise interval.

Biochemical and Hormone Markers in Firefighters: Effects of "Search, Rescue, and Survival Training" and Its Recovery

ABSTRACT

Ponce, T, Mainenti, MRM, de Barros, T, Cahuê, FLC, Fernanda, C, Piazera, BKL, Salerno, VP, and Vaisman, M. Biochemical and hormone markers in firefighters: effects of "search, rescue, and survival training" and its recovery. J Strength Cond Res 38(4): e189-e201, 2024-This study aimed to evaluate the hormonal and biochemical responses in military firefighter cadets to a search, rescue, and survival training (SRST) course. Forty-three male volunteers participated in the SRST over 15 days consisting of intense physical effort, sleep deprivation, and a survival period with food deprivation. At 3 timepoints (baseline, SRST, and 1 week rec), subjects submitted to blood collections, body composition examinations, physical performance evaluations, and cognitive function tests. After the SRST, lower values were registered for testosterone (764.0; 565.1-895.0 to 180.6; 133.6-253.5 ng·dl -1 ) and insulin-like growth factor-1 (IGF-1) (217; 180-238 to 116; 102-143 ng·ml -1 ). Increases were observed for cortisol (9.7; 8.2-11.7 to 18.3; 16.5-21,2 μg·dl -1 ), growth hormone (GH) (0.11; 0.06-0.20 to 2.17; 1.4-3.4 ng·ml -1 ), CP, GSSG, lactate dehydrogenase, alanine aminotransferase, and aspartate aminotransferase as well as the antioxidant response of superoxide dismutase and glutathione peroxidase. The values of gamma-glutamyl transferase were reduced. After 1 week of recovery, levels of GH, creatine kinase, GSH, and GSSG returned to baseline values ( p < 0.05). Vertical jump performance presented a regular positive correlation with testosterone (rho = 0.56 and p < 0.0001) and a strong negative correlation with cortisol (rho = -0.61 and p < 0.0001). Body fat showed a regular and positive correlation with both testosterone and IGF-1. We conclude that participation in the SRST caused significant hormonal and biochemical changes in individuals that correlated with a loss in physical performance. Importantly, the results suggest the need for longer recovery times before a return to normal military duties.

Effects of muscle fatigue on exercise-induced hamstring muscle damage: a three-armed randomized controlled trial

PURPOSE

Hamstring injuries in soccer reportedly increase towards the end of the matches' halves as well as with increased match frequency in combination with short rest periods, possibly due to acute or residual fatigue. Therefore, this study aimed to investigate the effects of acute and residual muscle fatigue on exercise-induced hamstring muscle damage.

METHODS

A three-armed randomized-controlled trial, including 24 resistance-trained males, was performed allocating subjects to either a training group with acute muscle fatigue + eccentric exercise (AF/ECC); residual muscle fatigue + eccentric exercise (RF/ECC) or a control group with only eccentric exercise (ECC). Muscle stiffness, thickness, contractility, peak torque, range of motion, pain perception, and creatine kinase were assessed as muscle damage markers pre, post, 1 h post, and on the consecutive three days.

RESULTS

Significant group × time interactions were revealed for muscle thickness (p = 0.02) and muscle contractility parameters radial displacement (Dm) and contraction velocity (Vc) (both p = 0.01), with larger changes in the ECC group (partial η2 = 0.4). Peak torque dropped by an average of 22% in all groups; stiffness only changed in the RF/ECC group (p = 0.04). Muscle work during the damage protocol was lower for AF/ECC than for ECC and RF/ECC (p = 0.005).

CONCLUSION

Hamstring muscle damage was comparable between the three groups. However, the AF/ECC group resulted in the same amount of muscle damage while accumulating significantly less muscle work during the protocol of the damage exercise.

TRIAL REGISTRATION

This study was preregistered in the international trial registration platform (WHO; registration number: DRKS00025243).

Can Blood Biomarkers Be Used to Assess Oxidative Stress in COPD Patients After Pulmonary Rehabilitation

Purpose

To determine the level of oxidative stress in the body due to pulmonary rehabilitation (PR) with thiols and disulfide and to investigate their relationship with indirect markers such as creatine kinase (CK), creatine kinase - MB (CK-MB), and lactate dehydrogenase (LDH), which show cell destruction.

Patients and Methods

Patients with chronic obstructive pulmonary disease (COPD) are included in inpatient and outpatient care. They were evaluated before and after for PR, and an exercise program was prescribed. In addition, native thiol (NT), total thiol (TT), disulfide (DS), LDH, CK, and CK-MB values were tested.

Results

The mean age of 21 patients was 63±7.31 years. Eleven of them were outpatients and 10 of them were inpatients. Most of the patients were male (M/F=20/1, 95.2/4.8%). There was a significant difference in pulmonary function tests (PFT), St. George Respiratory Questionnaire (SGRQ), and 1 repetition maximum (1RM) before and after the treatment (p<0.001). There was a correlation between PFT and 1RM upper extremity. While there was no significant difference between thiols and disulfide, according to GOLD scores, there was a significant difference in patients with level 3-MMRC. No correlation was found between LDH, CK, CK-MB, and thiols, DS. ΔCK was found to be associated with ΔDS, and ΔCK-MB with ΔNT, and ΔTT.

Conclusion

PR contributes to the antioxidant process by improving respiration and reducing oxidative stress. The decrease in LDH, CK with PR, increase in CK-MB, and correlation of CK with thiols and DS gave a different interpretation. In this case, it should be considered that oxidative stress may also be increased in people with high CK values.

Relationship Between Body Size and Skeletal Age with Muscle Damage in Young Soccer Players

This study verified the relationship between body size and skeletal age (SA) with the behavior of blood markers of muscle damage and delayed onset muscle soreness (DOMS) after a soccer match in the U-13 and U-15 categories. The sample consisted of 28 soccer players in the U-13 and 16 in the U-15 categories. Creatine kinase (CK), lactate dehydrogenase (LDH), and DOMS were evaluated up to 72 h after the match. Muscle damage was elevated at 0 h in U-13, and from 0 h to 24 h in U-15. DOMS increased from 0 h to 72 h in U-13 and from 0 h to 48 h in U-15. Significant associations of SA and fat-free mass (FFM) with muscle damage markers and DOMS were observed only in U-13, specifically at time 0 h, when SA explained 56% of CK and 48% of DOMS and FFM explained 48% of DOMS. We concluded that in the U-13 category, higher SA is significantly associated with muscle damage markers, and increase in FFM is associated with muscle damage markers and DOMS. Furthermore, U-13 players need 24 h to recover pre-match muscle damage markers and more than 72 h to recover DOMS. In contrast, the U-15 category needs 48 h to recover muscle damage markers and 72 h to recover DOMS.

Time Course of Performance Indexes, Oxidative Stress, Inflammation, and Muscle Damage Markers after a Female Futsal Match

BACKGROUND

Our aims were to investigate the time-course effects of a futsal match on performance, oxidative stress, and muscle damage markers, as well as inflammatory and antioxidant responses during a 6-day post-match period.

METHODS

Thirty-four female high-level futsal players were assessed on several oxidative stress, inflammation, subjective muscle soreness, subjective rate perceived exertion, and performance tests before a futsal match, immediately after, and 24 h to 144 h after.

RESULTS

Counter movement jump, 20 m, and 10 m sprints performance significantly decreased immediately after the match (p < 0.05) and returned to baseline 72 h post-match (p > 0.05). Delayed onset muscle soreness peaked 24 h post-match and rate perceived exertion peaked post-match (p < 0.05) and returned to baseline 96 h post-match (p > 0.05). Inflammatory biomarkers peaked at 24 h (p < 0.05) and remained significantly elevated for 72 h after the match (p < 0.05). Muscle damage biomarkers peaked at 24 h (p < 0.05) and remained significantly (p < 0.05) elevated for at least 72 h after the match. Oxidative stress markers peaked at 24 h-48 h (p < 0.05) and returned to baseline 120 h post-match (p > 0.05). In respect to antioxidant responses, these peaked at 24 h-48 h post-match (p < 0.05) and returned to baseline 120 h after the match (p > 0.05).

CONCLUSIONS

A single futsal match induces short/mid-term changes in performance, inflammation, oxidative stress, and muscle damage markers for about 72 h-96 h post-match.

A Single Bout of High Heels Dancing Causes an Increase in Circulating Markers of Muscle Tissue Degradation and MMP-3 in Young Healthy Women

Prolonged wearing of high heels can cause chronic injury and inflammation. Herein, we investigated the presence of muscle injury, inflammation, and neutrophil function in young women after a single bout of stiletto dance class. Sixteen volunteers (23.4 ± 3.8 years; 61.7 ± 8.1 kg; 23.4 ± 2.3 kg/m2; and 27.2 ± 3.8% body fat) participated in the study. The plasma biomarkers matrix metalloproteinase 3 (MMP-3), muscle damage (myoglobin (Mb), total creatine kinase (CK), and lactate dehydrogenase (LDH)), and inflammation (interleukin 8 (IL-8), tumour necrosis factor-alpha (TNF-α), interleukin (IL]-1β, and IL-6) were quantified before and immediately after a single stiletto class (60 min) of moderate intensity. After class, our data showed that the plasma concentration of MMP-3, Mb, and CK increased by 56% (p = 0.04; d = 0.8), 113% (p = 0.007; d = 1.1), and 21% (p < 0.001; d = 0.4), respectively. Reactive oxygen species produced by neutrophils and the plasma concentration of IL-8, TNF-α, IL-1β, and IL-6 were not affected under the study conditions. We concluded that a single bout of stiletto dance class caused muscle damage but did not alter the plasma concentration of proinflammatory cytokines. These findings are crucial in preventing the progress of chronic injuries that are often noted in dancers with synovitis and arthritis.

Effects of muscle damage indicators and antioxidant capacity after interval training on the 800-m records of adolescent middle-distance runners

To examine the effect of 10-week interval training (IT) at varying intensities on serum muscle damage indicators and antioxidant capacity and determine its effect on the 800-m records of adolescent middle-distance runners. Twenty male high-school middle-distance runners were randomized between the high-intensity IT (HIIT; n=10) and the medium-intensity IT (MIIT; n=10) groups. Three sessions/week for 10 weeks (total of 30 sessions) were performed; one session of IT was for 60 min. The high and medium exercise intensities were set at 90%-95% and 60%-70% heart rate reserve (HRR), respectively. Intensity at rest was 40% HRR for both groups. Weight training was performed at 60%-70% of one repetition maximum for two sessions/week. The changes in serum muscle damage indicators and antioxidant capacity in the two groups were measured, and their effects on the 800-m records were analyzed. The 10-week training reduced serum muscle damage indicators in middle-distance runners, but only the HIIT group displayed a decrease in creatine kinase. For the change in antioxidant capacity, the two groups demonstrated no significant change in malondialdehyde (MDA), whereas the HIIT group exhibited a significant increase in super-oxide dismutase (SOD). IT also reduced the 800-m records in middle-distance running, and the effect was stronger in the HIIT group. In conclusion, 10-week HIIT can have a positive effect on muscle damage indicators, showed a significant increase in SOD as a key indicator of anti-oxidant capacity, and improved the 800-m records in middle-distance runners.

Biomarkers of post-match recovery in semi-professional and professional football (soccer)

High-level football (soccer) players face intense physical demands that result in acute and residual fatigue, impairing their physical performance in subsequent matches. Further, top-class players are frequently exposed to match-congested periods where sufficient recovery times are not achievable. To evaluate training and recovery strategies, the monitoring of players' recovery profiles is crucial. Along with performance and neuro-mechanical impairments, match-induced fatigue causes metabolic disturbances denoted by changes in chemical analytes that can be quantified in different body fluids such as blood, saliva, and urine, thus acting as biomarkers. The monitoring of these molecules might supplement performance, neuromuscular and cognitive measurements to guide coaches and trainers during the recovery period. The present narrative review aims to comprehensively review the scientific literature on biomarkers of post-match recovery in semi-professional and professional football players as well as provide an outlook on the role that metabolomic studies might play in this field of research. Overall, no single gold-standard biomarker of match-induced fatigue exists, and a range of metabolites are available to assess different aspects of post-match recovery. The use of biomarker panels might be suitable to simultaneously monitoring these broad physiological processes, yet further research on fluctuations of different analytes throughout post-match recovery is warranted. Although important efforts have been made to address the high interindividual heterogeneity of available markers, limitations inherent to these markers might compromise the information they provide to guide recovery protocols. Further research on metabolomics might benefit from evaluating the long-term recovery period from a high-level football match to shed light upon new biomarkers of post-match recovery.

Effect of 8-week high-intensity intermittent running exercise and weight training on muscle and DNA damage in male and female ski major college students

This study assessed changes in blood muscle damage indicators and DNA damage indicators in lymph and urine after 8 weeks of high-intensity intermittent running and weight training in male and female college students majoring in skiing. This study aimed to find an effective training method by investigating differences in the effectiveness between men and women. A total of 20 male and female ski major college students conducted short-term high-intensity intermittent running and weight training in the morning and afternoon, respectively, 3 days a week for 8 weeks for 24 times in total. After 8 weeks of high-intensity intermittent running and weight training, changes in DNA damage indicators in the lymph and urine and muscle damage indicators in the blood were analyzed. The creatine kinase level significantly differed at rest pre-graded exercise testing (GXT) and 60 min of recovery post-GXT after training from that before training between the male and female groups. Although lactate dehydrogenase (LDH) levels decreased in both groups over time, no significant differences in LDH were found between the two groups. Second, DNA 8-hydroxydeoxyguanosine (8-OHdG) in the lymph was significantly different between the two groups at rest pre-GXT and 60 min of recovery post-GXT. 8-OHdG in the urine was significantly lower in the female group only at 60 min of recovery post-GXT. Partial sex differences were found in the reduction of muscle damage and DNA damage after 8 weeks of high-intensity intermittent running and weight training.

The Effect of 13 Weeks Long-Distance Bicycle Riding on Inflammatory Response Indicators Related to Joint Cartilage and Muscle Damage

This study was to investigate the effects of 13 weeks of long-distance cycling on biomarkers of joint cartilage, muscle damage and inflammation. All subjects in this study were seven participants of the “One Korea New-Eurasia Peace Cycle Expedition”, in which they rode cycles from Berlin, Germany to Seoul, Korea for thirteen weeks. The total course of the expedition was divided into three sub-courses: course 1 (from Berlin to Moscow), course 2 (from Moscow to Ulaanbaatar) and course 3 (from Ulaanbaatar to Seoul). All the selected participants rode 87.4 km/day (course 1), 70.4 km/day (course 2) and 57.6 km/day (course 3) on average, respectively. We collected their blood samples before the expedition in Seoul (S1), after course 1 in Moscow (M), after course 2 in Ulaanbaatar (U) and after the expedition in Seoul (S2), to analyze biomarkers of joint cartilage damage (Cartilage Oligomeric Matrix Protein; COMP), muscle damage (Creatine Phosphokinase; CPK, Lactate Dehydrogenase; LDH, Myoglobin), inflammation (Interleukin-6; IL-6, Interleukin-1β; IL-1β, Tumor Necrosis Factor-α; TNF-α, C-Reactive Protein; CRP) and stress hormone (Cortisol). According to this result, COMP (S1; 188.37 ± 46.68 ng/mL) showed a significant increase after the expedition course 1 (M; 246.69 ± 51.69 ng/mL, p = 0.012) and course 2 (U; 237.09 ± 62.57 ng/mL, p = 0.047), and recovered to the stable state after expedition course 3 (S2; 218.46 ± 34.78. p = 0.047). Biomarkers of muscle damage (CPK, LDH and Myoglobin) and inflammation (IL-6, IL-1β, TNF-α and CRP) were not significantly changed in all courses, but CRP (S1; 1.07 ± 0.76 ng/mL) showed a tendency to decrease after the expedition course 1 (M; 0.3 ± 0.1 mg/mL, p = 0.044). Lastly, the Cortisol level significantly increased in all courses (per p < 0.05), but the Cortisol level after expedition course 3 (S2; 21.00 ± 3.65 mg/mL) was lower than that of after the expedition course 1 (M; 24.23 ± 2.47 mg/mL, p = 0.028). In summary, it seems that repetitive and continuous 50−90 km/day of cycling can increase joint cartilage damage risk and stress hormone temporarily. However, this result suggests that the appropriate intensity of cycling for thirteen weeks does not increase physical damage, and rather enhances the human body to adapt to exercise training.

Effect of curcumin supplementation on exercise-induced muscle damage: a narrative review

Curcumin, a natural polyphenol extracted from turmeric, is a potent antioxidant and anti-inflammatory agent. In the past few decades, curcumin's ability to impact chronic inflammatory conditions such as metabolic syndrome, arthritis, and cancer has been widely researched, along with growing interest in understanding its role in exercise-induced muscle damage (EIMD). EIMD impacts individuals differently depending on the type (resistance exercise, high-intensity interval training, and running), intensity, and duration of the exercise. Exercise disrupts the muscles' ultrastructure, raises inflammatory cytokine levels, and can cause swelling in the affected limb, a reduction in range of motion (ROM), and a reduction in muscular force-producing capacity. This review focuses on the metabolism, pharmacokinetics of various brands of curcumin supplements, and the effect of curcumin supplementation on EIMD regarding muscle soreness, activity of creatine kinase (CK), and production of inflammatory markers. Curcumin supplementation in the dose range of 90-5000 mg/day can decrease the subjective perception of muscle pain intensity, increase antioxidant capacity, and reduce CK activity, which reduces muscle damage when consumed close to exercise. Consumption of curcumin also improves muscle performance and has an anti-inflammatory effect, downregulating the production of pro-inflammatory cytokines, including TNF-α, IL-6, and IL-8. Curcumin may also improve oxidative capacity without hampering training adaptations in untrained and recreationally active individuals. The optimal curcumin dose to ameliorate EIMD is challenging to assess as its effect depends on the curcumin concentration in the supplement and its bioavailability.

Capillary Blood Recovery Variables in Young Swimmers: An Observational Case Study

Sport diagnostics is still in pursuit of the optimal combination of biochemical and hematological markers to assess training loads and the effectiveness of recovery. The biochemical and hematological markers selected for a panel should be specific to the sport and training program. Therefore, the aim of this study was to evaluate the usefulness of selected biochemical and hematological variables in professional long-distance and sprint swimming. Twenty-seven participants aged 15–18 years took part in the study. Alanine aminotransferase (ALT), aspartate aminotransferase (AST), lactate dehydrogenase (LDH) and alkaline phosphatase (ALP) activities and creatinine (Cr), C-reactive protein (CRP), ferritin, total bilirubin (TB), direct bilirubin (DB) and iron concentrations were measured for 10 weeks and compared with the traditional sport diagnostic markers of creatine kinase (CK) activity and urea (U) concentration. Additionally, capillary blood morphology was analyzed. An effective panel should consist of measurements of CK and AST activities and urea, TB, DB and ferritin concentrations. These markers provide a good overview of athletes’ post-training effort changes, can help assess the effectiveness of their recovery regardless of sex or competitive distance and are affordable. Moreover, changes in ferritin concentration can indicate inflammation status and, when combined with iron concentration and blood morphology, can help to avoid iron deficiencies, anemia and adverse inflammatory states in swimmers.

Effect of 3 vs. 3 Soccer Small-Sided Game on Various Performance, Inflammatory, Muscle Damage and Hormonal Indicators in Semi-Professional Players

The purpose of this study was to examine the effect of a soccer small-sided game (SSG) on performance, inflammatory, muscle damage and hormonal indicators. Twenty-two male soccer players participated and were assigned to either experimental (EXP = 12) or control (CON = 10) groups. Subjective fatigue (RPE) and lactate (La¯) were measured during the SSG; vertical squat jump (SJ), 20-m sprint, creatine kinase (CK), interleukin-6 (IL-6), cortisol (C), and testosterone (T) were measured before (PRE), after (POST), 24 h, 48 h, and 72 h after the SSG in the EXP group. The heart rate during the SSG reached 92 ± 3% of their HRmax, whereas La¯ and RPE reached 13.02 ± 1.60 mmol·L−1 and 15 ± 1 after SSG, respectively. The IL-6, different among measurements (F (1.04, 11.50) = 504.82, p < 0.001), peaked (3.52 ± 0.43 pg·mL−1 [95%CI; 3.28−3.77]) after the SSG and returned to baseline 24 h later. The CK, different among measurements (F (1.76, 19.32) = 93.96, p < 0.001), peaked (536.58 ± 124.73U·L−1 [95%CI; 466.01−607.15]) 24 h after the SSG and remained significantly higher than PRE condition in POST and up to 72 h later. The T/C ratio, significantly different among measurements (F (1.73, 19.05) = 12.12, p < 0.001), was at its lowest (0.44 ± 0.16 [95%CI; 0.35−0.54]) immediately after the SSG (p < 0.05) and returned to baseline after 24 h. It seems that 48 h (at the most) after an SSG is adequate time for players to recover, and a high training load should be avoided sooner than 24 h after an SSG.

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.

Plasma lactate dehydrogenase and pyruvate kinase activity changes with body mass and age across birds and mammals

Birds and mammals produce most adenosine triphosphate (ATP) through mitochondrial oxidative phosphorylation, but when oxygen is not present in sufficient levels, ATP can be produced through anaerobic glycolysis. Pyruvate kinase (PK) catalyzes the final step of glycolysis by converting phosphoenolpyruvate and adenosine diphosphate (ADP) into pyruvate and ATP. Lactate dehydrogenase (LDH) is important for anaerobic glycolysis by catalyzing the conversion of pyruvate into lactate. In this study, we measured LDH and PK activities in plasma from birds and mammals in order to determine the relationship between LDH and PK with respect to body mass and age. Our results show that birds had a higher LDH and PK activity compared with mammals. There is a positive relationship between body mass and plasma LDH activity in birds only. However, this relationship disappears when the data are phylogenetically corrected. We did not observe a significant relationship between plasma LDH and age in birds or mammals. Plasma PK activity was negatively correlated with body mass in birds but not in mammals and positively associated with age in both birds and mammals. The relationship between LDH and PK with respect to body mass and age may be complex due to differences in metabolism in birds and mammals. Increases in LDH and PK activity with body mass in birds may be linked to anaerobic demands of flight, especially in larger birds. A decrease in LDH activity with age/MLSP (maximum lifespan) in mammals may reflect a differing metabolic shift as compared with birds. Increases in PK with age in both mammals and birds may help them cope with greater energetic needs as cells age.

Proposal of New Safety Limits for In Vivo Experiments of Magnetic Hyperthermia Antitumor Therapy

Simple Summary

Magnetic hyperthermia is a promising therapy for the treatment of certain types of tumors. However, it is not clear what the maximum limit of the magnetic field to which the organism can be subjected without severe and/or irreversible pathophysiological consequences is. This study aims to study the alterations at the physiological level that may occur after exposure to different combinations of frequency and intensity of the applied alternating magnetic field. Understanding the response to alternating magnetic field exposure will allow us to apply this type of antitumor treatment in a safer way for the patient, while achieving an optimal therapeutic result.

Abstract

Background: Lately, major advances in crucial aspects of magnetic hyperthermia (MH) therapy have been made (nanoparticle synthesis, biosafety, etc.). However, there is one key point still lacking improvement: the magnetic field-frequency product (H × f = 4.85 × 10⁸ Am⁻¹s⁻¹) proposed by Atkinson–Brezovich as a limit for MH therapies. Herein, we analyze both local and systemic physiological effects of overpassing this limit. Methods: Different combinations of field frequency and intensity exceeding the Atkinson–Brezovich limit (591–920 kHz, and 10.3–18 kA/m) have been applied for 21 min to WAG/RijHsd male rats, randomly distributed to groups of 12 animals; half of them were sacrificed after 12 h, and the others 10 days later. Biochemical serum analyses were performed to assess the general, hepatic, renal and/or pancreatic function. Results: MH raised liver temperature to 42.8 ± 0.4 °C. Although in five of the groups the exposure was relatively well tolerated, in the two of highest frequency (928 kHz) and intensity (18 kA/m), more than 50% of the animals died. A striking elevation in liver and systemic markers was observed after 12 h in the surviving animals, independently of the frequency and intensity used. Ten days later, liver markers were almost recovered in all of the animals. However, in those groups exposed to 591 kHz and 16 kA/m, and 700 kHz and 13.7 kA/m systemic markers remained altered. Conclusions: Exceeding the Atkinson–Brezovich limit up to 9.59 × 10⁹ Am⁻¹s⁻¹ seems to be safe, though further research is needed to understand the impact of intensity and/or frequency on physiological conditions following MH.

Coenzyme Q10 Supplementation and Its Impact on Exercise and Sport Performance in Humans: A Recovery or a Performance-Enhancing Molecule?

Evidence exists to suggest that ROS induce muscular injury with a subsequent decrease in physical performance. Supplementation with certain antioxidants is important for physically active individuals to hasten recovery from fatigue and to prevent exercise damage. The use of nutritional supplements associated with exercise, with the aim of improving health, optimizing training or improving sports performance, is a scientific concern that not only drives many research projects but also generates great expectations in the field of their application in pathology. Since its discovery in the 1970s, coenzyme Q10 (CoQ10) has been one of the most controversial molecules. The interest in determining its true value as a bioenergetic supplement in muscle contraction, antioxidant or in the inflammatory process as a muscle protector in relation to exercise has been studied at different population levels of age, level of physical fitness or sporting aptitude, using different methodologies of effort and with the contribution of data corresponding to very diverse variables. Overall, in the papers reviewed, although the data are inconclusive, they suggest that CoQ10 supplementation may be an interesting molecule in health or disease in individuals without a pathological deficiency and when used for optimising exercise performance. Considering the results observed in the literature, and as a conclusion of this systematic review, we could say that it is an interesting molecule in sports performance. However, clear approaches should be considered when conducting future research.

Plyometric training effects on physical fitness and muscle damage in high school baseball players

[Purpose]

The objective of this study was to investigate the effects of plyometric training on physical fitness and muscle damage in high school baseball players.

[Methods]

The participants in the study included 21 high school baseball players who are healthy and well-training. The participants were randomly allocated to the plyometric training (n=11) and control (n=10) groups. The plyometric training was applied 3 times a week for a total of 8 weeks and the control group took part in only regular baseball skills training without plyometric training. For physical fitness, measures included maximal strength (left and right hand-grip strength), muscle endurance (sit-up), agility (side-step), power (standing long jump), and balance (left and right Rhomberg test). For muscle damage, creatine kinase (CK) and lactate dehydrogenase (LDH) levels were measured.

[Results]

The results showed a significant interaction effect between time and groups in left hand-grip strength (P = 0.022), side-step (P = 0.004), and standing long jump (P < 0.001) after the 8-week plyometric training, with greater improvement in the plyometric training group than the control group. On the other hand, there was no significant interaction effect between time and groups in right hand-grip strength, situp, left and right Rhomberg test, CK level, and LDH level (P > 0.05).

[Conclusion]

In conclusion, 8-week plyometric training had a positive effect on improving physical fitness, such as maximal strength, agility, and power, in high school baseball players without causing additional muscle damage.

Basal Values of Biochemical and Hematological Parameters in Elite Athletes

The purpose of this study was to show how continuous exercise affects the basal values of biochemical and hematological parameters in elite athletes. A total of 14,010 samples (male = 8452 and female = 5558 (March 2011–March 2020)) from 3588 elite athletes (male = 2258 and female = 1330, mean age 24.9 ± 6.9 vs. 24.1 ± 5.5 years, respectively) from 32 sport modalities, were studied over 9 years to check the variation of basal biochemical and hematological parameter values. There were differences seen in the basal values of creatine kinase (CK), urea, creatinine, aspartate transaminase (AST), alanine aminotransferase (ALT), lactate dehydrogenase (LDH), potassium, total bilirubin, and eosinophil percentage compared to reference population data. However, other analytes showed narrow ranges of variation like glucose, total protein, albumin, sodium, hemoglobin, mean cell volume (MCV), and platelet count. Exercise produces changes in biochemical and hematological basal values of athletes compared to the general population, with the greatest variation in CK, but AST, ALT, LDH, potassium, and total bilirubin (TBil) show high values in serum, only with a wider distribution of values. The data here reflects the effect of exercise on biochemical and hematological parameter baseline ranges in elite athletes. As clinical laboratories use reference intervals to validate clinical reports, these “pseudo” reference intervals should be used when validating laboratory reports.

Effects of Eccentric vs. Concentric Sports on Blood Muscular Damage Markers in Male Professional Players

Simple Summary

Muscle eccentric contractions produce a higher degree of damage compared to concentric contractions. However, during sport practice (training and competition), eccentric as well as concentric actions appear at different levels. The presence of muscle-specific proteins in circulation is indicative of damage. The present report compares three sport disciplines: cycling, mainly concentric, volleyball, mainly eccentric in the legs and concentric in the arms, and basketball, mainly eccentric. The aim was to analyze the pattern of muscular injury blood markers in professional players in two moments of the season: after a training period and after a competition period. Results show that after a training period, muscle damage blood markers are higher in basketball and volleyball players, as expected due to their dominant eccentric component. However, during competition, these markers are higher in cyclists as a result of frequent eccentric actions. Therefore, the component eccentric–concentric is not defined exclusively by the sport discipline. The moment of the season (training vs. competition) has to be considered as well. This information could help sport professional to planify more specific training programs, preparations for competition, as well as post-exercise recovery.

Abstract

Background: Repetitive eccentric contractions can lead to higher degree of damage compared to repetitive concentric contractions. However, this type of exercise does not reproduce the real situations during the season in competitive sport disciplines. Methods: We analyzed the pattern of muscle damage blood markers in male professionals from three disciplines: cycling (n = 18), mainly concentric, vs. basketball (n = 12) and volleyball (n = 14), both mainly eccentric. Circulating muscle markers were analyzed in two moments of the regular season: after a 20-day training (no competition) period (T1) and after a 20-day period of high demanding competition (T2). Results: Blood levels of creatine kinase and myoglobin (muscle markers) increased in all groups at T2 compared to T1 as a result of competition intensity. The lower increases were noticed in cyclists at the end of both periods. Testosterone levels decreased at T2 compared to T1 in all disciplines, with lower levels found in cyclists. However, cortisol plasma levels decreased in basketball and volleyball players at T2, but increased significantly in cyclists, suggesting a limited adaptation to the effort. Conclusions: The pattern of circulating muscle markers is different depending of the demanding efforts (training vs. competition) of each particular discipline.

Rhabdomyolysis: A syndrome to be considered

Rhabdomyolysis is characterized by the release of intracellular elements after the destruction of skeletal muscle. Is characterized by the presence of muscle pain, weakness, and dark urine, associated with elevated creatine kinase (CK). The causes related to this syndrome are varied, being traumatic etiology, immobilization, sepsis, drugs and alcohol the most frequent. CK values are used for diagnosis and prognosis, being renal dysfunction the most serious complication. Treatment is based on early and intensive fluid therapy to avoid kidney complications.

Ankle muscle fatigability impairs body sway for more than 24 h

This study aimed to investigate if the impairing in postural control, induced by ankle fatiguing exercise, remains after 24/48 h in young adults. Center of Pressure (CoP) was assessed in 16 participants (23 ± 3 years old) before, immediately after an ankle fatigability induction protocol (FI) and after 24 or 48 h of recovery using two 60-s trials with eyes open (EO) and closed (EC). The FI consisted of performing the ankle plantar flexion and dorsiflexion movement repeatedly (0.5 Hz). Ankle muscle fatigability increased CoP anterior-posterior (AP - p < 0.02) and medial-lateral (ML - p < 0.009) root mean square (RMS), and AP (p < 0.01) mean velocity immediately after compared to before FI. These effects remained after 24/48 h of recovery: higher CoP AP (p < 0.03) and ML (p < 0.009) RMS. No significant effects for detrend fluctuation analysis and entropy analysis among periods of postural evaluations was found. Fatigue*visual condition interaction revealed an increased AP median frequency (p < 0.001) during EC compared to EO only immediately after FI. Young adults' body sway remains impaired until 48 h, but not the postural control adaptability and complexity. Visual information may not attenuate the late deleterious ankle muscle fatigability effects. Individuals should be cautious during balance tasks and exercise after fatiguing exercise in the next 24/48 h, therefore avoiding unbalances and falls.

Effects of Vitamin D in Post-Exercise Muscle Recovery. A Systematic Review and Meta-Analysis

Vitamin D is a key micronutrient modulating function and health in skeletal muscle. Therefore, we sought to systematically review the role of vitamin D in muscle recovery. A search in different databases (PubMed/MEDLINE, WOS, Google Scholar, and Scopus) was carried out following PRISMA^® and PICOS. The search period was from inception to April 2020. Changes in post-exercise muscle damage were quantified comparing experimental group vs. placebo in each study by using number of participants, standardized mean difference (SMD), and standard error of the SMD. Hedges’s g was used to calculate the SMDs for each study group and biased by the inverse of variance that allows calculating an overall effect and the 95% confidence interval (CI). The net vitamin D supplementation effect was calculated by subtracting the placebo SMD from SMD of the experimental group. The DerSimonian and Laird method was used as a random effect model, taking into account that the effect of vitamin D on muscular damage may vary according to the dose administered and additional moderators. Six studies were selected. In conclusion, regarding circulating levels of muscle biomarkers and additional limitations of the studies, it cannot be concluded that vitamin D supplementation exerts an effect in post-exercise muscle recovery. Likely, the anti-inflammatory action of vitamin D is quicker than the recovery of tissue structure and function. This aspect is pending verification in future research.

Biological Responses to Short-Term Maximal Exercise in Male Police Officers

The specifics of short-term physical exercise are similar to the immediate reaction demands placed on police officers. Identifying the physiological predisposition to short-term high-intensity exercise in male law enforcement officers will assist in understanding their metabolism and make a significant contribution to a much more personal and individualized workout program. This will improve physical fitness of individual officers, improving their preparedness for such times of emergency. This cross-sectional study was conducted to investigate the responses of hematological (erythrocytes, hemoglobin, hematocrit, leucocytes, monocytes, neutrophils, lymphocytes), hormonal (testosterone, cortisol, melatonin), biochemical (glucose, uric-acid, lactate, creatine-phosphokinase) data to short-term maximal exercise in male police officers (n = 20). Blood samples were collected before- and after- the running-based anaerobic sprint test (RAST), and biological values were corrected for fluid shifts. Data were mean ± standard deviation of differences (= after minus before RAST). After the RAST, values of cortisol, lactate, neutrophils, lymphocytes, and monocytes increased significantly by 7.01 ± 37.36 mmol/l, 7.55 ± 1.67 mmol/l, 0.17 ± 0.26 103/µl, 0.61 ± 0.28 103/µl, and 0.10 ± 0.13 103/µl, respectively. After the RAST, values of melatonin, uric-acid, creatine-phosphokinase, hemoglobin, and hematocrit decreased significantly by -13.24 ± 4.60 pg/ml, -13.28 ± 14.35 µmol/l, -10.23 ± 10.13 IU/l, -2.01 ± 0.81 g/dl, and -4.46 ± 0.59%, respectively. Biological data of male police officers were affected by sprint test. Understanding changes in biological data following short-term maximal exercise can further assist in a better understanding of anaerobic metabolism, which will be helpful to find available methods for coaches to quantify training loads.

Neospora caninum and/or Toxoplasma gondii Seroprevalence: Vaccination against PCV2 and Muscle Enzyme Activity in Seropositive and Seronegative Pigs

Neospora caninum and Toxoplasma gondii affect both humans and animals worldwide. To investigate their seroprevalence and differences in seropositivity between pigs vaccinated and unvaccinated against porcine circovirus 2 (PCV2), as well as differences in muscle enzyme activity between seropositive and seronegative pigs, blood samples were collected from 380 sows. Antibodies against T. gondii and N. caninum were detected by an indirect immunofluorescence antibody (IFA) assay, while the activities of creatine kinase (CK) and aspartate aminotransferase (AST) were biochemically assessed. Out of the 364 sows finally included in the study, 4.4%, 3.5%, and 0.5% were seropositive to T. gondii, N. caninum, or both. A significantly higher percentage of seropositivity against T. gondii and/or N. caninum in PCV2 unvaccinated pigs compared with vaccinated pigs was observed. Increased serum activities of CK and AST were detected in 71.43% and 100% of only against T. gondii (T+) and 63.64% and 90.91% of only against N. caninum (N+) seropositive sows, respectively, and were significantly higher compared to seronegative animals. T. gondii and N. caninum seropositivity, especially in presumed immunocompromised pigs, and the evidence of muscle damage highlight their importance as a zoonotic pathogen and animal model of human infection, respectively.

Effects of different ischemic preconditioning occlusion pressures on muscle damage induced by eccentric exercise: a study protocol for a randomized controlled placebo clinical trial

Introduction

Due to its greater generation of muscle strength and less metabolic demand, eccentric exercise has been widely used in rehabilitation and for improving physical fitness. However, eccentric exercise can induce muscle damage by providing structural changes and reduced muscle function, so even with the protection caused by the repeated bout effect from eccentric exercise, it is necessary to seek alternatives to reduce this damage caused by stress. Thus, ischemic preconditioning could represent an aid to reduce the damage muscle or increase the protective effect caused by eccentric exercise.

Objectives

To compare the effects of ischemic preconditioning, using different occlusion pressures, on acute and delayed responses to perceptual outcomes, markers of muscle damage, and performance in post-eccentric exercise recovery.

Methods

A randomized controlled placebo clinical trial will be carried out with 80 healthy men aged 18 to 35 years who will be randomly divided into four groups: ischemic preconditioning using total occlusion pressure, ischemic preconditoning with 40% more than total occlusion pressure, placebo (10 mmHg), and control. The ischemic preconditioning protocol will consist of four cycles of ischemia and reperfusion of five minutes each. All groups will perform an eccentric exercise protocol, and assessments will be carried out before, immediately after, and 24, 48, 72, and 96 h after the end of the eccentric exercise to evaluate creatine kinase, blood lactate, perception of recovery using the Likert scale, being sequentially evaluated, pain by the visual analog scale, pain threshold using a pressure algometer, muscle thickness by ultrasound, muscle tone, stiffness and elasticity by myotonometry, vectors of cell integrity through electrical bioimpedance, and maximal voluntary isometric contraction using the isokinetic dynamometer. The trial was registered at ClinicalTrials.gov (NCT04420819).

Discussion

The present study aims to present an alternative technique to reduce muscle damage caused by eccentric exercise, which is easy to apply and low cost. If the benefits are proven, ischemic preconditioning could be used in any clinical practice that aims to minimize the damage caused by exercise, presenting an advance in the prescription of eccentric exercise and directly impacting on the results of post-exercise recovery.

Trial registration

ClinicalTrials.gov NCT04420819. Registered on 19 May 2020; Last update 24 March 2021.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13063-021-05285-7.

Moderate intensity cycling is better than running on recovery of eccentric exercise-induced muscle damage

OBJECTIVE

To compare the effects of moderate intensity running and cycling on markers of exercise-induced muscle damage in men.

STUDY DESIGN

Randomized controlled trial.

SETTING

Laboratory.

PARTICIPANTS

Thirty volunteers were randomized in three groups [running (RG; n = 10), cycling (CG; n = 10) and control (CON; n = 10)] and were evaluated at baseline, post 24, 48 and 72 h of knee extensors' muscle damage protocol. CON performed passive recovery, while RG and CG performed active recovery immediately after the protocol, as well as 24 h and 48 h afterwards.

MAIN OUTCOMES

(i) maximal voluntary isometric contraction (MVIC); (ii) delayed-onset muscle soreness (DOMS); (iii) plasma creatine kinase (CK) and lactate dehydrogenase (LDH) levels.

RESULTS

No group-by-time interaction was found in any outcome evaluated (p > 0.05). All groups presented decreases in MVIC and increases in DOMS (p < 0.001), without differences in CK and LDH. Compared with CON, exercise groups presented likely beneficial effects for LDH, while only CG had a likely beneficial effect for DOMS. Lastly, CG presented likely/very likely beneficial effects for MVIC and DOMS compared to RG.

CONCLUSION

Although the null hypothesis analysis did not find differences, the magnitude-based inference analysis suggested that moderate intensity cycling have likely beneficial effects on knee extensor muscle recovery after eccentric exercise protocol.

The Intake of Kiwifruits Improve the Potential Antioxidant Capacity in Male Middle- and Long-Distance Runners Routinely Exposed to Oxidative Stress in Japan

Oxidation damages cells and muscles, and thus, causes injuries and fatigue, which negatively affect the conditioning of athletes. Thus, in this study, we aimed to investigate the effects of high-antioxidant fruits (kiwifruit) intake on oxidative stress level (d-ROMs) and antioxidant activity (BAP) in male middle- and long-distance runners routinely exposed to oxidative stress. This study was performed from May to July 2017 (Study 1) and October to December 2018 (Study 2). The subjects in Study 1 were 30 male runners, of which 15 consumed two yellow kiwifruits (Zespri^® SunGold Kiwifruit) per day for one month of the survey period (Intake group). The subjects of Study 2 were 20 male runners who had high d-ROMs from preliminary testing. These runners consumed two yellow kiwifruits (Zespri^® SunGold Kiwifruit) per day for two months. d-ROMs and BAP were measured using a free radical analyzer. In study 1, the d-ROMs decreased while the potential antioxidant capacity (BAP/d-ROMs ratio) increased in the Intake group. In study 2, BAP/d-ROMs ratio was higher after one and two months compared to that at pre-intervention. Study findings suggested that consumption of kiwifruits may reduce oxidative stress levels and increase antioxidant activity, resulting in improved potential antioxidant capacity.

Muscle damage in response to a single bout of high intensity concentric exercise in patients with Pompe disease

Background

In Pompe disease, resistance exercise could be an effective treatment to delay motor function impairment, however, the acute effects of this exercise modality are unclear.

Methods

In a prospective cohort study, we compared responses to a single bout of resistance exercise by serum markers of muscle damage and quantitative muscle magnetic resonance imaging (MRI) in patients (n=12) and age- and gender-matched healthy controls (n=12). Participants performed 50 maximal effort concentric knee flexions on a dynamometer.

Results

Twenty-four hours after exercise, levels of serum creatine kinase, lactate dehydrogenase and myoglobin increased in controls. In contrast, only myoglobin level increased in patients. All elevated serum markers declined by 48 hours after exercise in both groups. Mild soreness developed at 24 hours, which disappeared at 48 hours in both groups. In controls, MRI R2* relaxation rate reduced immediately and 24 hours after exercise, indicating increased water content and muscle perfusion. In patients, exercise had no effect on R2* values. The resistance exercise did not induce acute strength deficit in patients, rather, patients increased their strength by 24 hours. When serum marker changes were normalized to the magnitude of knee flexor tension developed during exercise, lactate dehydrogenase response was greater in patients.

Conclusions

Late-onset Pompe disease did not exacerbate exercise-induced muscle damage, however, lactate dehydrogenase may be monitored to screen high responders during high intensity resistance exercise interventions.

[Musculoskeletal laboratory diagnostics in competitive sport]

Hintergrund

Die labordiagnostische Untersuchung stellt eine wichtige Möglichkeit zur Beurteilung und Optimierung der Leistungs- und Regenerationsfähigkeit professioneller Athleten dar. Ferner ist sie für die Prävention, Diagnostik und Rehabilitation von Verletzungen und Überbelastungen von Bedeutung.

Fragestellung

Ziel dieser Arbeit ist die Darstellung muskuloskelettaler laborchemischer Parameter, die relevante Erkenntnisse für die medizinische Betreuung von Leistungssportlern liefern.

Material und Methoden

Literaturrecherche und narratives Review.

Ergebnisse

Die Bestimmung des Vitamin-D-, Calcium- und Knochenstoffwechsels stellt die laborchemische Basisdiagnostik im Rahmen der Beurteilung des Skelettstatus mit zusätzlichem präventivem Nutzen bezüglich muskuloskelettaler Verletzungen dar. Ferner können muskuläre Serummarker, z. B. Laktatdehydrogenase (LDH), Kreatinkinase (CK), Myoglobin und Aspartat-Aminotransferase (ASAT), helfen, eine metabolische Adaptation an das physische Training festzustellen und Aussagen über die muskuläre Arbeitslast und mögliche Schädigungen zu gewinnen. Die Energieverfügbarkeit kann durch eine entsprechende Bilanzierung sowie die laborchemische Bestimmung der Makro- und Mikronährstoffe eingeschätzt und optimiert werden.

Schlussfolgerungen

Die labordiagnostische Untersuchung besitzt in der Betreuung von Athleten eine sportartenübergreifende klinische Relevanz. Sie dient der Erreichung einer höchstmöglichen Leistungsfähigkeit sowie optimalen Prävention von Knochen- und Muskelverletzungen, wobei sämtliche Mangelzustände (z. B. Vitamin D) ausgeglichen werden sollten. Durch eine Periodisierung der laborchemischen Untersuchungen, mit zumindest zwei Labordiagnostiken im Jahr, und Aufstellung individueller Variabilitäts- und Referenzbereiche kann ferner eine bessere Beurteilbarkeit erreicht werden.

Safety evaluation of high-dose intake of casein-derived peptide Met-Lys-Pro in healthy adults: A randomized, double-blind, placebo-controlled trial

Met-Lys-Pro (MKP) is a casein-derived angiotensin I-converting enzyme inhibitory peptide with the potential to cross the blood-brain barrier. It has shown preventive effects against high blood pressure (BP) and cognitive decline in animal models and human studies. MKP shows good water solubility and can be blended into a variety of foods. However, its ease of intake may contribute to the possibility of overdose. Therefore, we aimed to evaluate the safety of high-dose intake of MKP in healthy adults by conducting a randomized controlled trial with 30 subjects. Participants were randomly allocated to the MKP (n = 15) or placebo (n = 15) group. Over 4 weeks, the MKP group received test powder containing a daily dose of 1,000 μg of MKP, five times the minimum effective dose for cognitive improvement, whereas the placebo group received dextrin powder containing no detectable MKP. No clinical problems were observed in anthropometric and BP measurements or in blood and urine parameters. No adverse events owing to MKP intake were observed. These findings suggest that consumption of MKP is safe, and that it may be applicable as a safe preventive measure against hypertension and cognitive decline in future.

An acute eccentric exercise increases circulating myomesin 3 fragments

Discovery of blood biomarkers to evaluate exercise-induced muscle damage have attracted many researchers and coaches. This study aimed to determine changes in circulating myomesin 3 fragments as a novel biomarker for exercise-induced muscle damage. Nine healthy males performed 10 sets of 40 repetitions of one-leg calf-raise exercise by the load corresponding to the half of their body weight. Muscle symptoms were evaluated by a visual analog scale (VAS). Blood samples were collected before and 2, 4, 24, 48, 72, and 96 h post-exercise. Plasma myomesin 3 fragments levels were significantly increased at 96 h after the eccentric exercise. The myomesin 3 fragments levels were correlated with other biomarkers of muscle damage and the muscle symptoms. These results suggest that the circulating myomesin 3 fragments levels are potential biomarkers reflecting eccentric exercise-induced muscle damage.

Markers of muscle damage and strength performance in professional football (soccer) players during the competitive period

Background

The present study investigated the impact of competitive soccer on the short-term changes in isometric strength of the adductor muscle group during the competitive season.

Methods

In this cohort study we evaluated the association between a serum marker of muscle damage [creatine phosphokinase (CPK)] and isometric strength of the adductor muscles of the hip in 30 professional football players (age: 26.7±2.9 years) during two seasons of the national top-level championship. Serum CPK level was determined the day before the match, 12–20, 36–48, 60–72 h after the match. The maximum voluntary isometric contraction force of the adductor muscles complex was determined immediately after having taken blood samples.

Results

There was evidence of a statistically significant positive association between age, body mass index (BMI), percentage of body fat, and muscle strength, and between weight and muscle strength. There was evidence of a statistically significant negative association between the level of CPK and the maximum isometric strength of the adductors of soccer players. Changes in CPK levels were associated with the muscle strength recovery trend (P<0.001). The strength/CPK ratio at different time points had a U-shaped curve.

Conclusions

Exercise induced muscle damage significantly affects the strength of the adductor muscle group of professional soccer players during the competitive period. The lower the CPK level, the greater the athletes' strength at a given time point. Also, the greater the decrease in CPK level, the greater the rate of strength restoration.

Mortality-and Health-Related Factors in a Community-Dwelling of Oldest-Older Adults at the Age of 90: A 10-Year Follow-Up Study

Mortality is obviously intended for epidemiological studies of community-dwelling older adults. There are several health-related factors associated with nutritional status and mortality. The aim of this study was to elucidate the risk factor for mortality in community-dwelling oldest-older adults at the age of 90 and clarify the structure of health-related factors associated with mortality. A 10-year follow-up study was performed for 93 subjects at the age of 90. The mean and median of their survival days were 2373 and 2581 days for women, and 1694 and 1793 days for men. By Cox's proportional hazards model, health-related factors associated with mortality were self-assessed for chewing ability, activities of daily living (ADLs), serum albumin, total cholesterol, serum creatinine, and gripping power for women but not for men. These factors interacted with each other, and the association of these factors was different in women and men. Self-assessed chewing ability was a powerful risk factor for mortality in women at the age of 90. It acted independently from nutritional status. For older adults, addressing healthy food choices together with improved oral functions is useful. However, risk factors for mortality may depend on the life stage of subjects. To investigate the risk factor for the mortality, the life course approach is necessary.

Effect of citrulline on post-exercise rating of perceived exertion, muscle soreness, and blood lactate levels: A systematic review and meta-analysis

BACKGROUND

Citrulline is one of the non-essential amino acids that is thought to improve exercise performance and reduce post-exercise muscle soreness. We conducted a systematic review and meta-analysis to determine the effect of citrulline supplements on the post-exercise rating of perceived exertion (RPE), muscle soreness, and blood lactate levels.

METHODS

A random effects model was used to calculate the effect sizes due to the high variability in the study design and study populations of the articles included. A systematic search of PubMed, Web of Science, and ClinicalTrials.gov was performed. Eligibility for study inclusion was limited to studies that were randomized controlled trials involving healthy individuals and that investigated the acute effect of citrulline supplements on RPE, muscle soreness, and blood lactate levels. The supplementation time frame was limited to 2 h before exercise. The types and number of participants, types of exercise tests performed, supplementation protocols for L-citrulline or citrulline malate, and primary (RPE and muscle soreness) and secondary (blood lactate level) study outcomes were extracted from the identified studies.

RESULTS

The analysis included 13 eligible articles including a total of 206 participants. The most frequent dosage used in the studies was 8 g of citrulline malate. Citrulline supplementation significantly reduced RPE (n = 7, p = 0.03) and muscle soreness 24-h and 48-h after post-exercise (n = 7, p = 0.04; n = 6, p = 0.25, respectively). However, citrulline supplementation did not significantly reduce muscle soreness 72-h post-exercise (n = 4, p = 0.62) or lower blood lactate levels (n = 8, p = 0.17).

CONCLUSION

Citrulline supplements significantly reduced post-exercise RPE and muscle soreness without affecting blood lactate levels.

Changes in Fatigue Recovery and Muscle Damage Enzymes after Deep-Sea Water Thalassotherapy

The purpose of this study was to verify the effect of deep-sea water thalassotherapy (DSWTT) on recovery from fatigue and muscle damage. The same exercise program is conducted in general underwater and deep-sea water to confirm the characteristics of deep-sea water through fatigue recovery and muscle damage enzymes. A total of 30 male college students were studied, including 10 belonging to the control group (CG), 10 in the water exercise group (WEG), and 10 in the deep-sea water exercise group (DSWEG). The DSWTT treatment consists of three components—preheating, treatment, and cooling—and the DSWTT program stretches and massages the entire upper body, lower body, back, and the entire body for a total of 25 min in a deep-sea tank. After the DSWTT program, blood tests were conducted to confirm the level of fatigue-related parameters and muscle damage enzymes. Fatigue-related parameters including glucose, lactate, ammonia, and lactate dehydrogenase (LDH), and the levels of muscle damage enzymes such as creatinine kinase (CK) and aspartate aminotransferase (AST) were measured. The results revealed that fatigue had a primary effect (p < 0.001) and exhibited strongly significant interaction (p < 0.001) with lactate, ammonia, and LDH levels, whereas the glucose level remained unchanged. The post hoc results showed a significant decrease in these parameters among DSWEG compared to CG and WEG (p < 0.01). Muscle damage enzymes showed a main effect (p < 0.001) and significant interaction (p < 0.001) with CK and AST (p < 0.001). The post hoc results showed a significant decrease in DSWEG compared with CG and WEG (p < 0.01). In conclusion, the DSWTT program applied to this study showed significant effects on muscle fatigue and muscle damage recovery. When the DSWTT program is applied in hot springs, it can have a positive effect on muscle fatigue and muscle damage recovery and can contribute to improving national health and quality of life. Further studies are needed to investigate DSWTT programs with various research subjects at different program temperatures, exercise times, and frequencies of treatment and exercise.

Physiological and Performance Impacts After Field Supramaximal High-Intensity Interval Training With Different Work-Recovery Duration

High-intensity interval training (HIIT) has numerous external load control variables. The management of these variables makes the physiological responses and performance presented by athletes also modify. The present study aimed to assess the activity of CK and LDH enzymes, performance and metabolic responses caused by two HIIT protocols above the maximum in male recreational runners. Fifteen recreational male runners performed two HIIT protocols in randomized order with multiple conditions: 1) H15 (n = 15), with a HIIT protocol of 15:15 work-recovery duration, and 2) H30 (n = 15) with a HIIT protocol of 30:30 work-recovery duration. Both protocols were performed at similar intensity (130% vV̇O_2max), one set until voluntary exhaustion. Blood samples were collected and used to capture the levels and activities of blood lactate (BLac: mmol⋅L^–1), glucose (GLU: mg⋅dL^–1), creatine kinase (CK: U⋅L^–1), and lactate dehydrogenase (LDH: U⋅L^–1). BLac and GLU were collected at pre, five, and ten minutes after the H15 and H30 protocols were performed. Blood samples were used to measure the activities of CK and LDH enzymes, which were verified 24 h before and 48 h after the protocols. The distance traveled (m), total time (s), and bouts performed (rep) were also registered. Significant differences between conditions H15 and H30 were observed in the bouts performed (p = 0.001; ES = 1.19). Several statistical differences were found over time for BLac [pre vs. post 5 (both conditions: p = 0.001), pre vs. post 10 (both conditions: p = 0.001), and post 5 vs. post 10 (H30: p = 0.004)], CK [pre vs. post 24 (H15: p < 0.001; ES = 0.97 and H30: p = 0.001; ES = 0.74) post 24 vs. post 48 (H30: p = 0.03; ES = 0.56)], and LDH [pre vs. post24 (H15: p = 0.008; ES = 1.07 and H30: p = 0.022; ES = 0.85). No statistical differences between conditions were observed for any blood parameter. Thus, the volunteers exhibited equal performance in both protocols, which resulted in a similar physiological response. Despite this similarity, in comparison to H15, the H30 protocol presented lower CK activity post 48 and lactate levels after 10 min post protocol.

Changes in Salivary Levels of Creatine Kinase, Lactate Dehydrogenase, and Aspartate Aminotransferase after Playing Rugby Sevens: The Influence of Gender

Rugby sevens is characterised by continuous exertion and great physical contact per unit of time, leading to muscle damage. It is important to identify markers that can quantify muscle damage in order to improve recovery strategies. The objective of this study was to evaluate the release dynamics of muscle damage markers creatine kinase (CK), lactate dehydrogenase (LDH), and aspartate aminotransferase (AST) in saliva samples when playing rugby sevens, analysing the influence of gender, during the rugby sevens university championship of Spain. The total sample included 27 athletes, divided into two teams of 14 men and 13 women between 18 and 31 years of age. CK, LDH, and AST were quantified from salivary samples collected from each athlete before and after three rugby sevens matches. The modified Borg scale of perceived exertion was also used after each match. When the results were analysed globally, there were no differences in CK and LDH before and after any match, but AST did show differences after two days of completing all matches. In terms of gender, the three enzymes showed different responses in men and women. Regarding the Borg scale, there were only significant differences between men and women after completing all mataches, with a greater perceived exertion in women. Based on our results, it can be stated that that serial matches of rugby sevens can cause changes of different magnitude in AST, CK and LDH activities in saliva, with AST showing the most significant variations and these changes are more pronounced in men than in women.

Effects of Hyperbaric Oxygen Therapy on Inflammation, Oxidative/Antioxidant Balance, and Muscle Damage after Acute Exercise in Normobaric, Normoxic and Hypobaric, Hypoxic Environments: A Pilot Study

The purpose of this study was to investigate the effects of hyperbaric oxygen therapy (HBOT) on inflammation, the oxidative/antioxidant balance, and muscle damage after acute exercise in normobaric, normoxic (NN) and hypobaric, hypoxic (HH) environments. Eighteen healthy males were selected and randomly assigned to three groups: exercise in NN conditions (NN group, n = 6), HBOT treatment after exercise in NN conditions (HNN group, n = 6), and HBOT treatment after exercise in HH conditions (HHH group, n = 6). All subjects performed treadmill running for 60 min at 75–80% maximum heart rate (HRmax) exercise intensity under each condition. The HBOT treatments consisted of breathing 100% oxygen at 2.5 atmosphere absolute (ATA) for 60 min. Blood samples were collected before exercise (BE), after exercise (AE), and after HBOT (AH) to examine inflammation (fibrinogen, interleukin-6 [IL-6], and tumor necrosis factor-α (TNF-α)), the oxidative/antioxidant balance (derivatives of reactive oxygen metabolites (d-ROMs) and the biological antioxidant potential (BAP)), and muscle damage (creatine kinase (CK) and lactate dehydrogenase (LDH)). Plasma fibrinogen, serum IL-6, CK, and LDH levels were significantly increased AE compared to BE in all groups (p < 0.05). Plasma fibrinogen levels were significantly decreased AH compared to AE in all groups (p < 0.05), and the HNN group had a significantly lower AH compared to BE (p < 0.05). Serum IL-6 levels were significantly decreased AH compared to AE in the HNN and HHH groups (p < 0.05). Serum CK levels were significantly decreased AH compared to AE in the HHH group (p < 0.05). Serum LDH levels were significantly decreased AH compared to AE in the HNN and HHH groups (p < 0.05), and the NN and HNN groups had significantly higher AH serum LDH levels compared to BE (p < 0.05). These results suggest that acute exercise in both the NN and HH environments could induce temporary inflammatory responses and muscle damage, whereas HBOT treatment may be effective in alleviating exercise-induced inflammatory responses and muscle damage.

Impact of hydrogen-rich gas mixture inhalation through nasal cannula during post-exercise recovery period on subsequent oxidative stress, muscle damage, and exercise performances in men

Molecular hydrogen has been suggested to have a cytoprotective effect on the whole body and to enhance exercise performances. However, the effect of hydrogen-rich gas mixture (HG) inhalation on physiological responses has been poorly investigated. We examined the impact of acute HG inhalation on subsequent oxidative stress, muscle damage, and exercise performances during the recovery period after a strenuous exercise. This is a two-trial, double-blind, crossover, repeated measures study. Eight physically active male volunteers inhaled HG (estimated fraction of inspired oxygen and hydrogen were 21.57 and 4.08% at most, respectively) or normal gas (placebo, ambient air 400 m above sea level) during a 60-minute recovery phase after oxidative stress-inducing exercise) completion comprising 30-minute treadmill running at an intensity corresponding to 75% of maximal oxygen uptake and squat jumps (5 sets × 10 repetitions). Before oxidative stress-inducing exercise and 10 minutes after the post-exercise gas inhalation, blood and urine samples were obtained and exercise performances (jumping ability; pedaling power output; muscle strength) were evaluated. Post-exercise HG inhalation attenuated the increase in urinary 8-hydroxydeoxyguanosine excretion rate (P < 0.05), a DNA oxidation marker, and the reduction in the countermovement jump height (P < 0.05), compared with Placebo inhalation. Other exercise performances and blood oxidative stress and muscle damage markers did not differ between HG and Placebo inhalation. Moreover, the increase in urinary 8-hydroxydeoxyguanosine excretion rate was significantly associated with countermovement jump performance reduction (r = -0.78, P < 0.01). These findings suggested that HG inhalation during post-exercise recovery period might improve exercise performance via reducing systemic oxidative damage. The study was approved by the Human Research Ethics Committee of the University of Yamanashi (approval No. H29-006) on June 28, 2017.

Effects of the 5-m Shuttle Run Test on Markers of Muscle Damage, Inflammation, and Fatigue in Healthy Male Athletes

Physical exercise is often associated with increases in muscle damage markers and inflammation. However, biomarkers of muscle damage and inflammation responses to the 5-m shuttle run test (5mSRT) have not yet been evaluated. The aim of the present study was to investigate effects of the 5mSRT on muscle damage markers, inflammation, and perception of fatigue and recovery in healthy male athletes. Fifteen male amateur team sports players (age: 20 ± 3 yrs, height: 173 ± 7 cm, body-mass: 67 ± 7 kg) participated in this study. Blood biomarkers were collected at rest, 5 min after, and 72 h after the 5mSRT to measure muscle damage (i.e., creatinine kinase (CK), lactate dehydrogenase (LDH), aspartate aminotransferase (ASAT), and alanine aminotransferase (ALAT)) and inflammation (i.e., C-reactive protein (CRP)). Best distance (BD), total distance (TD), fatigue index (FI), and percentage decrement (PD) during the 5mSRT were assessed. Perceived recovery (PRS) and delayed onset muscle soreness (DOMS) were recorded before, 5 min after, and 72 h after the 5mSRT; perceived exertion (RPE) was recorded before, during, and 72 h after the 5mSRT. Muscle damage biomarkers post 5mSRT showed a significant increase compared to pre 5mSRT (p < 0.001) levels ((i.e., CK (190.6 ± 109.1 IU/L vs. 234.6 ± 113.7 IU/L), LDH (163.6 ± 35.1 IU/L vs. 209.9 ± 50.8 IU/L), ASAT (18.0 ± 4.4 IU/L vs. 21.7 ± 6.2 IU/L), and ALAT (10.2 ± 3.4 IU/L vs. 12.7 ± 3.8 IU/L)) and 72 h post 5mSRT (p < 0.001) levels ((CK (125.3 ± 80.5 IU/L vs. 234.6 ± 113.7 IU/L), LDH (143.9 ± 36.6 IU/L vs. 209.9 ± 50.8 IU/L), ASAT (15.0 ± 4.7 IU/L vs. 21.7 ± 6.2 IU/L), and ALAT (8.6 ± 2.4 IU/L vs. 12.7 ± 3.8 IU/L)). CRP was also significantly higher post 5mSRT compared to pre 5mSRT (2.1 ± 2.5 mg/L vs. 2.8 ± 3.3 mg/L, p < 0.001) and 72 h post 5mSRT (1.4 ± 2.3 mg/L vs. 2.8 ± 3.3 mg/L, p < 0.001). Significant correlations were reported between (i) physical performance parameters (i.e., PD, FI, TD, and BD), and (ii) markers of muscle damage (i.e., CK, LDH, ASAT, and ALAT) and inflammation (i.e., CRP). Similarly, DOMS and RPE scores were significantly higher post 5mSRT compared to pre 5mSRT (2.4 ± 1.0UA vs. 6.7 ± 1.1UA and 2.1 ± 0.6 UA vs. 8.1 ± 0.6 UA, respectively p < 0.001) and 72 h post 5mSRT (1.9 ± 0.7 UA vs. 6.7 ± 1.1 UA and 1.5 ± 0.6 UA vs. 8.1 ± 0.6 UA, respectively p < 0.001). PRS scores were significantly lower post 5mSRT as compared to pre 5mSRT (6 ± 1 UA vs. 3 ± 1 UA, p < 0.001) and 72 h post 5mSRT (7 ± 1 UA vs. 3 ± 1 UA, p < 0.001). Significant correlations existed between (i) performance parameters (PD, FI, TD, and BD) and (ii) RPE, PRS, and DOMS. The 5mSRT increased biomarkers of muscle damage and inflammation, as well as the DOMS and RPE and reduced the PRS. Seventy-two hours was sufficient for fatigue recovery induced by the 5mSRT. PD is better than FI for the calculation of performance decrements during the 5mSRT to represent fatigue.

Effects of a Futsal Game on Metabolic, Hormonal, and Muscle Damage Indicators of Male Futsal Players

Bekris, E, Gioldasis, A, Gissis, I, Katis, A, Mitrousis, I, and Mylonis, E. Effects of a futsal game on metabolic, hormonal and muscle damage indicators of male futsal players. J Strength Cond Res XX(X): 000-000, 2020-The aim of this study was to examine the effects of a futsal game on several metabolic, hormonal, and muscle damage indicators. Twenty-one male top-level futsal players participated in the study. Players were divided into 2 groups according to playing time: the long playing time (LPT) group and the short playing time (SPT) group. Game intensity parameters such as percentage of the HRmax and blood lactate concentration, as well as metabolic, hormonal, and muscle damage indicators were examined before and after a futsal game. The results showed that during the game, the intensity was up to 93% of HRmax and lactate concentrations ranged from 5.8 to 21.8 mmol·L. The LPT group showed an increased lactate dehydrogenase level compared with the SPT group (p < 0.05). Similarly, creatine kinase was significantly increased in the LPT group (p < 0.05) after the game. By contrast, nonsignificant differences were observed between groups for alanine transaminase (ALT-SGPT), aspartate transaminase (AST-SGOT), and gamma-glutamyl transferase enzymes (p > 0.05). The testosterone/cortisol ratio (T/C) reduced for both groups after the game (p < 0.05). The results of this study indicated that a futsal game have a significantly effect on several hormonal, metabolic, and muscle damage indicators for players who participate for a longer playing time in the game. Therefore, the evaluation of these volumes could assist coaches to organize specific, effective, and individualized training programs.