Mechanical Determinants of Sprinting and Change of Direction in Elite Female Field Hockey Players.

Profile determination in field hockey is critical to determining athletes' physical strengths and weaknesses, and is key in planning, programming, and monitoring training. This study pursued two primary objectives: (i) to provide descriptive data on sprinting, deceleration, and change of direction (COD) abilities and (ii) to elucidate the mechanical variables that influence sprint and COD performance in elite female field hockey players. Using radar and time-gate technology, we assessed performance and mechanical data from 30 m sprinting, deceleration, and COD tests for 26 elite female hockey players. A machine learning approach identified mechanical variables related to sprint and COD performance. Our findings offer a framework for athlete categorization and the design of performance-enhancing training strategies at the international level. Two pivotal mechanical variables-relative maximum horizontal force (F0) and maximum velocity (Vmax)-predominantly influence the times across all tested distances. However, the force-velocity profile (FVP) and horizontal deceleration do not influence the variance in the COD test outcomes. These insights can guide the design, adjustment, and monitoring of training programs, assisting coaches in decision making to optimize performance and mitigate injury risks for female hockey players.

Effects of peppermint oil inhalation on vertical jump performance in elite young professional soccer players: A double-blinded randomized crossover study.

Aims: To evaluate peppermint essential oil (PEO) inhalation's effect on young soccer athletes' motor performance. Methods: A randomized crossover design was used to test the effect of the PEO. Eleven U-17 soccer players were evaluated into two conditions (PEO and Placebo - PLA). The players were tested in squat jump and countermovement jump and inhaled PEO or PLA and 10 min later performed the physical tests again. A mixed ANOVA was performed to test the hypotheses. Results: Main effects were found for the time in jumping height in the CMJ (p = 0.037). No main and interaction effects were found in the SJ variables. Conclusion: From the results, decrease CMJ performance acutely, both conditions presented decrease in JH, but based in effect size, PLA decrease is higher (more sample size for corroborate this) possibly due to improvements in the eccentric yielding sub-phase, where mentioned phase could be reflecting neural changes (required experimental verification). The PEO could be the interest in trainers for use before of match or in the half-time for minimize the decreased of physical performance by the rest.

Corrigendum: Effects of weight divisions in time-motion of female high-level Brazilian Jiu-jitsu combat behaviors.

[This corrects the article DOI: 10.3389/fpsyg.2023.1048642.].

Behavior of female judo weight divisions on approach and grip phases in different judo rules: The top 20 athletes from the 2016 and 2020 Olympic cycles.

In judo combat, the approach and gripping phases play a crucial role in determining victory, and it is believed that they can be influenced by the current rules. The objective of this study was to compare the technical-tactical actions executed by female judokas in the approach and gripping subphases during international competitions held in the 2016 and 2020 Olympic cycles, which featured different rules. We analyzed 1332 combat videos from the top 20 female judo athletes in the world rankings. These videos were equally distributed across weight divisions in the 2016 and 2020 Olympic cycles (48 kg = 132; 52 kg = 72; 57 kg = 109; 63 kg = 96; 70 kg = 69; 78 kg = 106; >78 kg = 82; total = 666 combats per cycle). The athletes in the 2020 cycle spent more time executing approach actions without contact with the judogi (formless: 2020 = 26.9; 2016 = 21.3 s; p < 0.001) and less time attempting grips (2020 = 24.6; 2016 = 31.2 s; p < 0.001) than the 2016 athletes. Additionally, the 2020 athletes spent less time on one-handed grips (left collar: 2020 = 7.1; 2016 = 7.9 s; p = 0.017; right sleeve: 2020 = 4.6; 2016 = 5.6 s; p = 0.018; left sleeve: 2020 = 4.7; 2016 = 5.2 s; p = 0.031) compared to the 2016 athletes. In both Olympic cycles, athletes devoted the most time to traditional grips (left collar right sleeve: 2016 = 12.3 ± 19.9; 2020 = 12.2 ± 17.5; right collar left sleeve: 2016 = 11.5 ± 20.6; 2020 = 12.3 ± 19.9 s). Differences in the approach subphases between Olympic cycles had varying impacts on different weight divisions (formless = 52 kg, 57 kg, 78 kg; right anteroposterior = 52 kg, 57 kg, 70 kg; grip attempts = 57 kg, 63 kg, 70 kg, 78 kg, >78 kg; p < 0.05), as did changes in grip types (right collar; left collar; left sleeve = 70 kg; right sleeve = >78 kg; right dorsal = 63 kg; left dorsal = 63 kg, 78 kg; right collar left sleeve = 48 kg, 52 kg; right dorsal left sleeve = 78 kg; right dorsal left collar = 48 kg, 70 kg; right dorsal left dorsal = 48 kg, 63 kg; p < 0.05). There were notable technical-tactical shifts in the behavior of female athletes between the Olympic cycles with different rules, and these findings should be taken into account for specialized training in female judo.

Effects of weight divisions in time-motion of female high-level Brazilian Jiu-jitsu combat behaviors.

Coaches and psychologists can use time-motion analysis to elaborate specific interventions for female BJJ athletes, increasing specific training context and reducing unnecessary psychological and physical demands and injuries. Therefore, the present study aimed to analyze high-level BJJ female athletes in the 2020 Pan-American Games by comparing the weight categories on the time-motion analysis. The time-motion analysis (i.e., approach, gripping, attack, defensive actions, transition, mounting, guard, side control, and submissions) of 422 high-level female BJJ combats was divided and compared by weight category as follows: Rooster (n = 8), Light Feather (n = 18), Feather (n = 122), Light (n = 84), Middle (n = 74), Medium Heavy (n = 44), Heavy (n = 36), Super Heavy (n = 36), using p ≤ 0.05. The main results indicated that the Super heavyweight category [3.1 (5.8;119.9) s] had a shorter gripping time than other weight categories, p ≤ 0.05. In contrast, roosters [7.2 (3.5;64.6) s] had longer gripping, transition [14.0 (4.8;29.6) s], and attack time [76.2 (27.7, 93.2)] than the light feather, middlers, and heavier weight categories, p ≤ 0.05. These findings should be considered for the psychological interventions and training prescription.

Dynamic Stretching Increases the Eccentric Rate of Force Development, but not Jump Height in Female Volleyball Players.

The present study aimed to analyze the effect of static and dynamic stretching exercises on the rate of force development (RFD) during the eccentric braking phase and jump height in a countermovement jump (CMJ) in female volleyball players. Thirty female volleyball players were randomly distributed in a static stretching (n = 10; SG), a dynamic stretching, and (n = 10; DG) a control group (n = 10; CG). A force plate and a 3D analysis system were employed to detect the eccentric braking phase during the CMJ. The RFD was analyzed in RFD (RFDi) intervals and the accumulated RFD (RFDa), and normalized to body mass. The SG experienced a likely small decrease in the RFDa (mean difference -17.4 N/s/kg) and a likely small decrease in the RFDi (mean difference -19.1 N/s/kg). Contrarily, the DG showed a likely small increase in the RFDa (mean difference 31.2 N/s/kg) and a most likely small increase in the RFDi (mean difference 34.8 N/s/kg). The effect of both static and dynamic stretching on jump height was trivial. Practitioners should consider utilizing dynamic stretching exercises instead of static stretching before a competition in female volleyball players. Further research is needed in order to find complementary strategies during the warm-up that could increase jump height.

Training at moderate altitude improves submaximal but not maximal performance-related parameters in elite rowers.

Maximal oxygen consumption (V̇O2max), physiological thresholds, and hemoglobin mass are strong predictors of endurance performance. High values of V̇O2max, maximal aerobic power (MAP), and power output at anaerobic thresholds are key variables in elite rowers. Endurance athletes often use altitude training as a strategy to improve performance. However, no clear evidence exists that training at natural altitude enhances sea-level performance in elite rowers. This study aimed to evaluate the effect of altitude training on rowing-performance parameters at sea level. The study was conducted on eleven rowers (Six females, five males) from the Chilean National Team during a 3-week moderate altitude training (∼2,900 m. a.s.l.) under the live high-train high (LHTH) model. It included a rowing ergometer maximal incremental test and blood analysis (pre and post-altitude). Gas exchange analysis was performed to measure V̇O2max, ventilatory thresholds (VTs) and rowing economy/efficiency (ECR/GE%). LHTL training improves performance-related variables at sea level (V̇Emax: 3.3% (95% CI, 1.2-5.5); hemoglobin concentration ([Hb]): 4.3% (95% CI, 1.7-6.9); hematocrit (%): 4.5% (95% CI, 0.9-8.2); RBC (red blood cells) count: 5.3% (95% CI, 2.3-8.2); power at VT2: 6.9% (95% CI, 1.7-12.1), V̇EVT2: 6.4% (95% CI, 0.4-12.4); power at VT1: 7.3% (95% CI, 1.3-13.3), V̇EVT1: 8.7% (95% CI, 1.6-15.8)) and economy/efficiency-related variables (ECRVT2: 5.3% (95% CI, -0.6 to -10.0); GE(%): 5.8% (95% CI, 0.8-10.7)). The LHTH training decreased breathing economy at MAP (-2.8% (95% CI, 0.1-5.6)), pVT2 (-9.3% (95% CI, -5.9 to -12.7)), and pVT1 (-9.3% (95% CI, -4.1 to -14.4)). Non-significant changes were found for V̇O2max and MAP. This study describes the effects of a 3-week moderate altitude (LHTH training) on performance and economy/efficiency-related variables in elite rowers, suggesting that it is an excellent option to induce positive adaptations related to endurance performance.

Effects of plyometric training on softer vs. Harder surfaces on jump-related performance in rugby sevens players.

This study aimed to compare jump-related performance after plyometric training on harder vs. softer surfaces in rugby sevens players. Fourteen players were randomly assigned to the harder surface group (H-G, n = 7) and softer surface group (S-G, n = 7). Three times per week, in the morning, the players performed plyometric training on different surfaces and strength training. Before and after the 4-week intervention period, squat jump (SJ), countermovement jump (CMJ), and CMJ with arms (CMJA) tests were performed to measure vertical jump displacement (d), rate of force development (r), and power (p). The main results indicated a significant improvement in S-G for CMJd (∆% = +8.2%; p = 0.029; ES = 0.59) and for CMJAp (∆% = +8.7%; p = 0.035; ES = 0.44). These improvements were significant compared to H-G for CMJAd (F1,12 = 8.50; p = 0.013; η p 2 = 0.41; ES = 0.83) and CMJAp (F1,12 = 7.69; p = 0.017; η p 2 = 0.39; ES = 0.79). This study reveals that performance related to the counter movement jump with arms on softer surfaces after 4-week plyometric training improved vertical jump displacement and lower body power in rugby sevens players.

Concussion vs. resignation by submission: Technical-tactical behavior analysis considering injury in mixed martial arts.

This research study verified the technical-tactical actions during the mixed martial arts (MMA) fights to generate serious enough injury to stop the MMA round, determining technical-tactical potential risk factors for injury in official MMA combats, according to Concussion or Resignation per Submission. A total of 990 rounds with concussions and 627 resignations per submission were considered with severe injury (i.e., a fight ended by a doctor or referee). All injuries were diagnosed and managed by attending ringside physicians during the MMA fights and rounds and had a continuous technical-tactical behavior analysis, p ≤ 0.05. The leading cause of concussion was due to head trauma (~90%), with higher dependence on head strikes scored actions. Comparisons between Concussion and Resignation per Submission combats demonstrated differences between distance head strikes actions [13(6,25) vs. 9(4,18) frequencies], clinch head strikes actions [1(0;4) vs. 1(0;3) frequencies], ground head strikes actions [1(0;8) vs. 2(0;10) frequencies] and takedowns actions [0(0;1) vs. 1(0;2) frequencies]. This information may provide significant evidence regarding the doctor stoppage in concussion combats and when it could be called by officials supervising MMA.

Rapid Weight Loss of Up to Five Percent of the Body Mass in Less Than 7 Days Does Not Affect Physical Performance in Official Olympic Combat Athletes With Weight Classes: A Systematic Review With Meta-Analysis.

Given the relevance of the effects that weight loss can generate on the physical performance in athletes, this study performed a systematic review with meta-analysis of the published literature on rapid weight loss (RWL) and examined its impact on the physical performance in Official Olympic combat sports athletes. The "Preferred Reporting Items for Systematic Reviews and Meta-Analysis" (PRISMA) guidelines were followed to ensure an ethical and complete reporting of the findings. PubMed, SPORT Discus, and EBSCO were the electronic databases explored for article retrieval and selection. The following string was applied: "RWL" OR "weight loss" OR "weight reduction" AND "judo" OR "wrestling" or "taekwondo" or "boxing" AND "performance." Based on the quality analysis, conducted according to the "Tool for the assessment of study quality and reporting in exercise training studies" (TESTEX), ten articles achieved a score >6 points. The meta-analysis showed a significant difference in pre- vs. post-weight loss (p = 0.003) and no effects in pre- vs. post-power and strength performance analysis (p > 0.05 for both results). Based on our systematic review and meta-analysis of the literature, RWL up to ≤5% of the body mass in less than 7 days does not influence performance outcomes in Official Olympic combat athletes with weight classes, considering the strength and power measures.

The effects of weight categories on the time-motion analysis of female high-level judo athletes between the 2016 and 2020 Olympic cycles.

This study compared the time of female judo combat phases in international competitions between two Olympic cycles (2016; 2020) according to weight divisions (48 kg = 132; 52 kg = 72; 57 kg = 109; 63 kg = 96; 70 kg = 69; 78 kg = 106; >78 kg = 82; total = 666 combats/cycle). The behaviors of 1,332 high-level female judo combats were randomly observed over two Olympic cycles (2016 = 666; 2020 = 666) from the top 20 athletes in the world ranking by weight division. We performed time-motion analysis according to the combat phase and sequential judo actions (approach, gripping, attack, defense, groundwork, pause, and effort: pause ratio) considering the moment when the combat ended (Regular time = RT; Golden score = GS). The weight division groups were compared between Olympic cycles (2016; 2020), and p < 0.05 was defined as significant. The main results showed that 2020 athletes spent less time in the gripping (p = 0.005), attack (p < 0.001), defense (p < 0.001), groundwork (p<0.001) and pause (p = 0.002) phases than 2016 athletes. However, compared by the end-of-combat, 2020 female athletes spent less time in all combat phases for RT combats (p < 0.001), and more time in the approach phase for GS combats (p < 0.05) than in 2016. The 2016 weight divisions showed a higher diversity in the effort: pause ratio (2.5:1-3.4:1), whereas the 2020 weight divisions had values closer to each other (2.8,1-3:1). Analyzing each weight division separately and by the end-of-combat, the main results showed that (p < 0.05): 48, 63, 70, and 78 kg reduced the time in almost every phase of RT combat (except for: 63 kg = gripping and attack; 70 kg = approach and groundwork; 78 kg = approach); 48 and 57 kg increased the groundwork time in GS combats whereas 78 kg decreased; 52 kg and 78 kg increased the GS approach time. The temporal behavior of the combats changed between the Olympic cycles with different rules. These data must be considered to understand the characteristics of each group and to prescribe specialized training in female judo.

Effect of a Six Week In-Season Training Program on Wrestling-Specific Competitive Performance.

The effect of multi-component training on specific performance is under-researched in wrestlers. The aim of this study was to determine the effect of six weeks of multi-component training on The Special Wrestling Fitness Test (SWFT) performances of wrestlers who were preparing for an international championship, and to, additionally, determine their inter-individual adaptive variability. The wrestlers (n = 13; 7 females; all international level) underwent technical-tactical and physical fitness training for the six weeks before the championship, 12 sessions per week (i.e., 36 h per week). Before and after the intervention the athletes were assessed with the SWFT, a wrestling-specific competitive performance test that includes measurements for throws, heart rate response to the SWFT, and the SWFT index. Significant pre-post intervention improvements were noted for throws (pre = 23.5 ± 2.9; post = 24.9 ± 3.6; p = 0.022) and SWFTindex (pre = 14.9 ± 2.2; post = 14.1 ± 2.2; p = 0.013. In conclusion, six weeks of multi-component training improved wrestling-specific competitive performances in highly-trained wrestlers, although with a meaningful inter-subject variability.

Changes in the Mechanical Properties of the Horizontal Force-Velocity Profile during a Repeated Sprint Test in Professional Soccer Players.

The objective was to analyze the changes in the horizontal force-velocity profile (HFVP) during the execution of repeated sprinting. Methods: Seventeen first-division Chilean soccer players completed a repeated sprint protocol consisting of eight sprints of 30 m with 25-s pauses between repetitions. The behavior of HFVP variables in each attempt was recorded from video recordings and analysis in the MySprint® application. Results: Differences (p < 0.05) were found between sprints in the following: time (T), starting from sprint 5 (F = 35.6; η2p = 0.69); theoretical maximum speed (V0), starting from sprint 4 (F = 29.3; η2p = 0.51); maximum power (PM), starting from sprint 5 (F = 17; η2p = 0.52); rate of decrease in force index produced at each step (DRF), starting from sprint 1 (F = 3.20; η2p = 0.17); and RF10, starting from sprint 1 (F = 15.5; η2p = 0.49). In comparison, F0 and RFpeak did not present any differences (p > 0.05). Conclusion: The HFVP variables more sensitive to the effects of fatigue induced by an RSA protocol are those associated with the production of force at high speeds, being V0, DRF, and Pmax, while those that contribute to the generation of force at the beginning of the sprint, F0 and RFpeak, do not present essential variations.

Effects of Olympic Combat Sports on Older Adults' Health Status: A Systematic Review.

The aim of this systematic review was to analyse the studies centered on the effects of Olympic combat sports (OCS [i.e., boxing, fencing, judo, karate, taekwondo, wrestling]) on older adults' physical-functional, physiological, and psychoemotional health status. The review comprised randomised-controlled trials with OCS interventions, including older adults (≥60 years), and measures of physical-functional, physiological, and/or psychoemotional health. The studies were searched through SCOPUS, PubMed/MEDLINE, Web of Science, PsycINFO, and EBSCO databases until 5 January 2021. The PRISMA-P and TESTEX scales were used to assess the quality of the selected studies. The protocol was registered in PROSPERO (code: CRD42020204034). Twelve OCS intervention studies were found (scored ≥ 60% for methodological quality), comprising 392 females and 343 males (mean age: 69.6 years), participating in boxing, judo, karate, and taekwondo. The qualitative analysis revealed that compared to controls, OCS training improved muscle strength, cardiorespiratory capacity, agility, balance, movement, attention, memory, mental health, anxiety, and stress tolerance. Meta-analysis was available only for the chair stand test, and an improvement was noted after OCS training compared to control. In conclusion, OCS interventions improves older adults' physical-functional, physiological, and psychoemotional health. Our systematic review confirms that OCS training has high adherence (greater than 80%) in older adults.

Caffeine improves biochemical and specific performance after judo training: a double-blind crossover study in a real judo training situation.

BACKGROUND: Nutritional ergogenic aids are foods or nutrients that can improve physical performance. Among these foods with ergogenic properties, caffeine has shown that it can increase the fat catabolism, strength, and improve the cognition and time reaction of an athlete, therefore, it is hoped that it can improve the performance of judokas. This study through a double-blind crossover (supplement X placebo) protocol, investigated the effects caffeine supplementation (single capsule containing 5 mg/kg body mass intake 60 min before the session) on biochemical, anthropometrical, physical, subjective and hemodynamic variables measured before, during and after two typical judo trainingcxs sessions (120-min: 40-min of gymnastics; 40-min of specific technics and; 40-min of judo combat). METHODS: 8 high-level athletes (21.4 ± 2.0 years; 83.6 ± 15.2 kg; 1.8 ± 0.1 m; 17.9 ± 7.0 Fat%) were evaluated before and after each training for body mass, hydration, upper and lower limb power, performance in the special judo fitness test (SJFT), free fatty acids (FFA) in plasma, uric acid, glucose, lactate, heart rate, and pain. In addition, heart rate, FFA in plasma, uric acid, glucose, lactate, rating of perceived exertion and pain were assessed during the training. RESULTS: At 120 min, supplementation resulted in a higher concentration of plasma FFA (1.5 ± 0.5 vs. 1.0 ± 0.3 mmol/L; p = 0.047) and lactate (4.9 ± 1.8 vs. 3.0 ± 1.2 mmol/L; p = 0.047), and a lower concentration of uric acid (5.4 ± 0.9 vs. 7.0 ± 1.5 mg/dL; p = 0.04). Supplementation also resulted in performance maintenance (fatigue index) in the SJFT (Δ0.3 ± 2.0 vs Δ1.7 ± 2.5, for caffeine and placebo respectively, p = 0.046). No adverse effects were observed. CONCLUSION: Based on the applied dose, intake time, and sample of this study, we can conclude that caffeine produces an ergogenic biochemical effect, and improves performance in judo athletes.

Comparisons of Motor Actions and Biomechanical Assessments of Judo Techniques Between Female Weight Categories.

This study aimed to perform motor action and biomechanical analysis of techniques in female judo athletes separated by weight categories of 638 female bouts (103 extra lightweight <48 kg, 140 half lightweight 48>52 kg, 65 lightweight 52>57 kg, 73 half middleweight 57>63 kg, 77 middleweight 63>70 kg, 80 half heavyweight 70>78 kg and 60 heavyweight >78 kg). All bouts were analyzed following the phases of approach, gripping, defensive action, attack, also biomechanical analysis of techniques and groundwork was performed (p ≤ .05). Results indicated that lightweight athletes presented lower attempts to grip, right collar grip and left collar grip frequencies than other categories. Extra lightweight judokas presented lower right back grip and left back and sleeve grip frequencies as well as lower occurrence of techniques with arm and leg lever scored than half lightweight athletes, while half lightweight athletes demonstrated higher frequency of techniques with waist lever variable scored than lightweight ones. These findings should be considered for training prescription.

Making Decisions and Motor Actions with Technical Biomechanical Classifications in Male Judo Weight Categories.

The aim of the study was to compare motor action variables of judo combat phases and technical biomechanical assessment of the seven weight categories. The sample was composed of 638 bouts (176 of extra lightweight <66 kg, 289 of half lightweight 66 > 73 kg, 180 of lightweight 73 > 81 kg, 244 of half middleweight 81 > 90 kg, 174 of middleweight 81 > 90 kg, 151 of half heavyweight 90 > 100 kg and 142 of heavyweight >100 kg) during motor actions of approach, gripping, attack, defense and groundwork combat phases, verifying the interactions between them by Markov chains and comparisons by Kruskall-Wallis and Dunn post hoc tests (p ≤ .05). The results demonstrated that lighter weight categories showed higher approach phases than the heavyweight category, and the lightweight group demonstrated higher defensive action frequencies than the half lightweight category and heavyweight athletes. Heavyweight and middleweight categories demonstrated higher groundwork combat frequencies than lighter weights, and the heavyweight category showed higher pause frequencies than the lightweight category. Regarding the decision-making model, the main transitions presented by the Markov chains showed higher prevalence of the following combinations: gripping occurring before the lever and length attacks, lever attack followed by the length attack, and length attack occurring earlier than the groundwork phase.

Technical-Tactical Behaviors Analysis of Male and Female Judo Cadets' Combats.

This brief research report showed technical-tactical behaviors of male and female judo cadets during combats, comparing the frequency and time of judo combat actions, techniques and penalties. The data was composed for 3,240 sequential technical-tactical behavior analysis from 108 female and 300 male cadet combats recorded of public judo championships. Combat, standing combat moments, approach action, gripping action, attack, groundwork actions and pause moment were observed and determinant technical-tactical behaviors (frequencies of actions, penalties and type of attacks) analysis were done with FRAMI software, followed by Mann-Whitney and Student's t-test, p ≤ 0.05. Our main results indicated that male cadets with 58.66s ± 50.26s demonstrated longer gripping action than female with 38.44s ± 30.44s, as standing combat (tachi-waza) had differences between male with 96.8s ± 72s and female athletes with 75.85s ± 56.97s. Moreover, male cadets had higher sacrifice techniques (sutemi-waza) actions than female athletes. This information could be used to a best performance associated with "psyching-up" as much as it could be used on physical training and technical-tactical ability of female and male cadets.

COVID-19-Related Restrictions and Quarantine COVID-19: Effects on Cardiovascular and Yo-Yo Test Performance in Professional Soccer Players.

The present study aimed to verify the quarantine's effects during a serious viral outbreak on the cardiovascular and performance associated with the Yo-Yo test in a sample of professional soccer players. 20 high-level soccer players (n = 20; age: 26 ± 4 years-old; weight: 76.85 ± 6.7 kg; height: 179 ± 6 cm) participated in this study. The intermittent Yo-Yo test was performed pre- and post- COVID-19 quarantine in a random order. During each test, the soccer players' running performance outcomes were monitored using a portable 5-Hz GPS with a 100 Hz accelerometer and a paired t-test was conducted at a p-value of ≤ 0.05. The main results demonstrated significant differences between pre- versus post-COVID-19 quarantine in the following variables: relative distance (161.7 ± 5.9 > 141.1 ± 33.8 m/min), maximal speed (18.7 ± 0.9 > 18.2 ± 0.6 km/h), acceleration (60 ± 20 frequency > 52 ± 16 frequency), deceleration (34 ± 13 frequency > 27 ± 6 frequency), sprints > 19 km/h [0.8 (0.2;3)% >0.5 (0;0.5)%], and in high intensity running distance [16.48 (2.68;41.64)m > 0.827 (0.164;3.0)m]. We concluded that COVID-19-related restrictions and quarantine COVID-19 demonstrated adverse effects on professional soccer players' Yo-Yo tests performance.

Instrumental validity and intra/inter-rater reliability of a novel low-cost digital pressure algometer.

BACKGROUND: Pain assessment is a key measure that accompanies treatments in a wide range of clinical settings. A low-cost valid and reliable pressure algometer would allow objective assessment of pressure pain to assist a variety of health professionals. However, the pressure algometer is often expensive, which limits its daily use in both clinical and research settings. OBJECTIVES: This study aimed to assess the instrumental validity, and the intra- and inter-rater reliability of an inexpensive digital adapted pressure algometer. METHODS: A single rater applied 60 random compressions on a force platform. The pressure pain thresholds of 20 volunteers were collected twice (3 days apart) by two raters. The main outcome measurements were as follows: the maximal peak force (in kPa) and the pressure pain threshold (adapted pressure algometer vs. force platform). Cronbach's α test was used to assess internal consistency. The standard error of measurement provided estimates of measurement error, and the measurement bias was estimated with the Bland-Altman method, with lower and upper limits of agreement. RESULTS: No differences were observed when comparing the compression results (P = 0.51). The validity and internal intra-rater consistencies ranged from 0.84 to 0.99, and the standard error of measurement from 0.005 to 0.04 kPa. Very strong (r = 0.73-0.74) to near-perfect (r = 0.99) correlations were found, with a low risk of bias for all measurements. The results demonstrated the validity and intra-rater reliability of the digitally adapted pressure algometer. Inter-rater reliability results were moderate (r = 0.55-0.60; Cronbach's α = 0.71-0.75). CONCLUSION: The adapted pressure algometer provide valid and reliable measurements of pressure pain threshold. The results support more widespread use of the pressure pain threshold method among clinicians.