Latest research in football - week 24 - 2023

As previous literature updates, I have performed a PubCrawler search looking for football articles in NCBI Medline (PubMed) and GenBank databases. 


Following studies were retrieved for this week:

#1 Using the Y-balance Test as a Predictor Tool for Evaluating Non-contact Injuries in University League Football Players: A Prospective Longitudinal Study

Reference: Cureus. 2023 May 21;15(5):e39317. doi: 10.7759/cureus.39317. eCollection 2023 May.

Authors: Khalid M Alkhathami 

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Summary: Background Football is a highly competitive sport, and participants can experience various contact and non-contact sports injuries in the sporting process. In any elite sport, screening players using different scientific tools is an important injury prevention strategy. The Y- Balance test (YBT) was found to be a predictive tool for non-contact injury. However, the use of criteria from these tests to predict injuries has not been substantiated and should be further investigated. Purpose The aim of this study was to determine the predictors for injury among athletes using baseline YBT, number of matches, and minutes of physical activity; the cutoff scores for predictors of injury, including baseline YBT, number of matches, and minutes of physical activity; and the clinical prediction rules for predicting injury in this population. Methods A total of 39 young student football players were included in this study. The mean age was 20.28 years, and the mean body mass index (BMI) was 23.83 kg/m2. A baseline assessment of the participant's characteristics was taken and each participant performed the YBT once before starting the league. After the university league football players had finished their tournament, we asked them questions related to non-contact injuries. Results The results showed that the prevalence of injury was 17.95% among this population. An increase in the YBT score was significantly associated with a decrease in the odds of having an injury [odds ratio (OR) 95% confidence interval (CI): 0.94 (0.88, 0.99), p = 0.047). In addition, the number of matches was significantly associated with an increase in the odds of having an injury p = 0.012. However, the minutes of physical activity were not statistically significant p = 0.065. The highest Youden index was ≤97.89, with a sensitivity of 87.50% and specificity of 71.43%, for the posterior medial reach and ≤92.88, with a sensitivity of 90.62% and specificity of 57.14%, for the posterior lateral reach. The clinical prediction rule was an area under the curve (AUC) of 0.88. Conclusions The results of the study provide evidence for the potential utility of the YBT as a predictor tool for evaluating non-contact injuries in university league football players. By identifying players with lower YBT scores who were at higher risk for injury, targeted interventions could be implemented to address functional movement deficits and potentially reduce injury risk.



#2 "Kickstart to Recovery": An Irish Football Program for Mental Health Service Users

Reference: OTJR (Thorofare N J). 2023 Jun 23;15394492231177281. doi: 10.1177/15394492231177281.

Authors: Hannah Casey, Jenny Johnston, Maurice Dillon, Clodagh Nolan

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Summary: The "Kickstart to Recovery" program is a collaboration between Irish mental health occupational therapists and the Football Association of Ireland. This pilot study aimed to investigate whether participants experienced changes in quality of life, recovery, social gains, and the meaning of football following participation in the program. A quantitative pre-post study design was employed, with 27 participants completing a questionnaire consisting of outcome measures aimed to measure the above changes. Findings revealed statistically significant improvements in the Short Form 36 Health Survey Questionnaire (SF-36) "Energy/Fatigue" domain for the total sample and the Recovery Assessment Survey-Domains and Scales (RAS-DS) "Mastering My Illness" domain for first-time program participants. Statistically significant results were found for domains of "Social Functioning" and "Emotional Wellbeing" in groups incorporating additional social elements. The Engagement in Meaningful Activities Survey (EMAS) showed no change for the personal meaning participants attributed to football; however, high pre-test scores were noted. The "Kickstart to Recovery" program is attributed as a possible factor contributing to these results.



#3 The immediate effects of foam rolling of the hamstrings muscle group on the contractile properties of the knee muscles in football players

Reference: J Bodyw Mov Ther. 2023 Jul;35:326-331. doi: 10.1016/j.jbmt.2023.04.007. Epub 2023 Apr 20.

Authors: Globokar E, Ipavec M, Vreček N, Vauhnik R

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Summary: Excessive amounts of intense training, without adequate recovery time, can overload the musculoskeletal, immune, and metabolic systems, resulting in a potentially negative effects on later exercise performance. During the competitive period, the ability to recover after intense training and competition is an important factor of success in soccer. The purpose of this study was to determine the effect of hamstring foam rolling on the knee muscle contractile properties in soccer players, after a sports-specific load. 20 male professional soccer players were included and contractile properties of the biceps femoris, rectus femoris, vastus medialis and vastus lateralis muscles were measured with tensiomyography, before and after a Yo-Yo interval test and after 5 × 45 s of hamstring foam rolling. Additionally, active and passive knee extensibility before and after the intervention were measured. A mixed linear model was performed to determine the differences between the mean values of the groups. The experimental group performed foam rolling, while the control was resting. Five repetitions of 45 s of hamstring foam rolling had no statistically significant effect (p > 0.05) on any of the measured muscles following the Yo-Yo interval test or foam rolling intervention. There were no statistically significant differences in delay time, contraction time and maximum muscle amplitude between groups. Active and passive knee extensibility did not differ between groups. It seems that foam rolling does not affect mechanical properties of the knee muscles or hamstring extensibility in soccer players, after a sports-specific load.



#4 Exploring the impact of athletic identity on gender role conflict and athlete injury fear avoidance in male English professional academy football players

Reference: Sci Med Footb. 2023 Jun 18;1-9. doi: 10.1080/24733938.2023.2224293. Online ahead of print.

Authors: I Cranswick, D Tod, P Clarke, A Jones

Summary: Men's academy football can encourage a commitment to the athletic role and masculine norms. When injured, the ability to fulfil an athletic masculine identity is threatened and athletes may experience injury fear-avoidance behaviours as part of a negative injury appraisal. The aim of the study was to explore whether higher athletic identity (AI) was associated with higher gender role conflict and injury-related fear-avoidance. Seventy-two male English academy footballers completed an Athletic Identity Measurement Scale (AIMS), Gender Role Conflict Scale (GRCS), and Athlete Fear Avoidance Questionnaire (AFAQ) based on self-reported historical injuries. Correlational analyses were conducted for all variables, and a one-way ANOVA was used to compare high, moderate, and low AI. AIMS was significantly positively correlated with two GRCS subscales: success, power, and competition (SPC) and restricted affectionate behaviour between men (RAM). AIMS exclusivity also positively correlated with SPC and AIMS negative affectivity positively correlated with GRCS total and RAM. Additionally, the current study showed that high and moderate levels of AI had significantly higher levels of total GRCS than those with low AI. No significant results were found for AIMS, GRCS, and AFAQ. Results suggest that players with higher and more exclusive AI may be susceptible to masculine role conflicts, specifically, SPC and RAM, especially when there is a risk to their athletic role. The current study informs sport and health professionals of the need to monitor AI and masculine conformity in academy-level footballers to minimise gender-role conflict and potential maladaptive rehabilitation responses when their identities are threatened.



#5 Match running performance profiles of amputee football players at the national level

Reference: Sci Rep. 2023 Jun 19;13(1):9882. doi: 10.1038/s41598-023-36856-0.

Authors: Jarosław Muracki, Michał Nowak, Adam Kawczyński, Ana Filipa Silva, Filipe Manuel Clemente

Summary: Even though running performance and positional profiles in football are well described, amputee football (AF) has different characteristics of the movement, pitch dimensions, and time played. There is a gap in the scientific literature about positional profiles based on running performance in AF. This study aimed to investigate the differences between positions, the influence of the amputation level or defect of the lower limb (LD), the differences in running performance between halves, and the relationship with the final match result. Thirteen AF National Team players were monitored by Global Navigation Satellite System (GNSS), tracking 24 official international matches for 17 months. Values of top speed, peak acceleration, peak deceleration, average distance per minute, sprint mean speed, GPS load per minute, inertial load per minute (Gs load/min), number of sprints per minute, and a number of impacts per minute were analyzed for defenders (DEF), midfielders (MID) and forwards (FOR). Additional factors analyzed were amputation level (below the knee, low amputation-LA or over the knee, high amputation-HA or defect of the lower limb-LD) and the match's final result. Midfielders had significantly higher running performance parameters compared to other positions (greater top speed than DEF (+ 0.3 m/s; p < 0.001) and FOR (+ 0.2 m/s; p = 0.045), greater peak acceleration and deceleration than DEF (+ 0.5 m/s2 for both measures; p < 0.001) and FOR (+ 0.4 and + 0.3 m/s2; p < 0.001 and p = 0.036, respectively), greater GPS load/minute than DEF (+ 0.2 load/min; p = 0.001) and FOR (+ 0.3 load/min; p < 0.001), greater Gs load per minute than DEF (+ 2.7 load/min; p < 0.001) and FOR (+ 1.8 load/min; p < 0.001), greater number of impacts per minute than DEF (+ 0.2 n/min; p < 0.001) and FOR (+ 0.2 n/min; p < 0.001). Players with LD had significantly higher running performance than those with LA or HA. In the match's second half, a decrease in running performance was registered. The trend of running more when losing could be observed-AF players had higher running parameters in lost matches, but the differences were not statistically significant. Further research complied with contextual game analysis is needed to assess the running performance of AF players deeply.



#6 Older adults' and service providers' experiences of a settings-based health promotion initiative in English football

Reference: Health Promot Int. 2023 Jun 1;38(3):daad027. doi: 10.1093/heapro/daad027.

Authors: Patricia C Jackman, Aoife Lane, Jacquelyn Allen-Collinson, Hannah Henderson

Summary: The study was undertaken to explore the experiences of older adults and service providers in a settings-based health promotion initiative in a football club. We conducted semi-structured interviews with 10 older adults attending an 'Extra Time Hub' (ETH) and two staff delivering the initiative. Our reflexive thematic analysis generated six themes. Findings revealed the brand of the sports club attracted some to join the ETH, but through partnerships with local agencies, the initiative was also successful in widening participation beyond older adults with an interest in football. Participants perceived that the ETH was beneficial for their mental health, helped them develop social connections, and promoted positive physical activity experiences. Moreover, the variety of pleasures derived from participation were also discussed. Our findings also illustrate the central role of staff in older adults' experiences of this form of health promotion. Overall, this study contributes to understandings of settings-based health promotion activities in sports clubs, and also demonstrates the potential for sports clubs to widen engagement with the local community through health promotion for older adults.



#7 Leveraging football accelerometer data to quantify associations between repetitive head impacts and chronic traumatic encephalopathy in males

Reference: Nat Commun. 2023 Jun 20;14(1):3470. doi: 10.1038/s41467-023-39183-0.

Authors: Daniel H Daneshvar, Evan S Nair, Zachary H Baucom, Abigail Rasch, Bobak Abdolmohammadi, Madeline Uretsky, Nicole Saltiel, Arsal Shah, Johnny Jarnagin, Christine M Baugh, Brett M Martin, Joseph N Palmisano, Jonathan D Cherry, Victor E Alvarez, Bertrand R Huber, Jennifer Weuve, Christopher J Nowinski, Robert C Cantu, Ross D Zafonte, Brigid Dwyer, John F Crary, Lee E Goldstein, Neil W Kowall, Douglas I Katz, Robert A Stern, Yorghos Tripodis, Thor D Stein, Michael D McClean, Michael L Alosco, Ann C McKee, Jesse Mez

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Summary: Chronic traumatic encephalopathy (CTE) is a neurodegenerative tauopathy associated with repetitive head impacts (RHI), but the components of RHI exposure underlying this relationship are unclear. We create a position exposure matrix (PEM), composed of American football helmet sensor data, summarized from literature review by player position and level of play. Using this PEM, we estimate measures of lifetime RHI exposure for a separate cohort of 631 football playing brain donors. Separate models examine the relationship between CTE pathology and players' concussion count, athletic positions, years of football, and PEM-derived measures, including estimated cumulative head impacts, linear accelerations, and rotational accelerations. Only duration of play and PEM-derived measures are significantly associated with CTE pathology. Models incorporating cumulative linear or rotational acceleration have better model fit and are better predictors of CTE pathology than duration of play or cumulative head impacts alone. These findings implicate cumulative head impact intensity in CTE pathogenesis.



#8 Anticipatory effects on side-step cutting biomechanics in Women's Australian Football League players

Reference: BMJ Open Sport Exerc Med. 2023 Jun 14;9(2):e001587. doi: 10. 1136/bmjsem-2023-001587. eCollection 2023.

Authors: Tess Rolley, Stephen D Gill, Meghan Keast, Tom Reade, Richard Page, Jason Bonacci, Julian Stella, Brett Johnson, Aaron Fox

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Summary: Reactive side-step cutting manoeuvres are linked to anterior cruciate ligament (ACL) injuries in Women's Australian Football League (AFLW) matches. We explored knee joint moments and ground reaction forces (GRFs) in AFLW players when performing anticipated and unanticipated side-stepping. Sixteen AFLW players (age=25.3±4.2 years; height=1.71±0.06 m; mass=68.4±4.7 kg) completed anticipated and unanticipated side-stepping trials during which full-body three-dimensional kinematics and kinetics were recorded. One-dimensional statistical parametric mapping paired t-tests were used to compare three-dimensional knee moments during weight acceptance and GRFs during the stance phase between anticipated and unanticipated conditions. Unanticipated side-stepping incurred lower knee flexion (18%-39% of stance, p<0.01) and abduction (11%-24% of stance, p<0.01) moments. Braking and propulsive GRFs were lower and higher, respectively, across the majority of stance phase (6%-90% of stance, p<0.01) in unanticipated side-stepping. Vertical GRFs were lower in unanticipated side-stepping in the early stance phase (14%-29% of stance, p<0.01). Contrary to existing literature, AFLW players exhibited knee joint moments associated with reduced ACL loading when performing unanticipated side-stepping. Players appeared to adopt a 'cautious' approach to the unanticipated side-step (ie, decelerating at the change of direction), by reducing braking and vertical GRFs in the early stance phase of cutting. This approach may be implausible to employ or detrimental to performance during matches. AFLW ACL injury prevention programmes may be enhanced with greater exposure to scenarios that replicate reactive match-play demands when aiming to improve side-stepping biomechanics.



#9 The effect of match location and travel modality on physical performance in A-League association football matches

Reference: J Sports Sci. 2023 Jun 21;1-8. doi: 10.1080/02640414.2023.2227831. Online ahead of print.

Authors: Darryl E Hands, Xanne A K Janse de Jonge, G C Livingston, Nattai R Borges

Summary: This study investigated the impact of match location and travel modality on physical performance of an Australian A-League association football team. Match location comprised of a home vs away comparison; while travel modality compared home matches, road travel, short-flight travel, and long-flight travel. Both models accounted for match result, opposition quality and total distance covered. Physical performance was defined as average running intensity (m.min-1), low-speed activity (LSA), high-speed activity (HSA), very high-speed activity (VHSA), high-intensity efforts (HIE) and sprint efforts. Statistical significance was accepted at p < 0.05. Match location results demonstrated significantly greater average running intensity and LSA for away matches and significantly greater HSA for home matches. Travel modality results demonstrated significantly greater LSA for road travel compared to home matches and long-flight travel, while HSA was significantly greater for home matches and long-flight travel than for road travel. Additionally, home matches demonstrated significantly greater VHSA than road travel. Assessing the impact of travel modality on physical performance provides more contextual information than solely home vs away. Coaches may use this information to plan travel to mitigate detrimental effects on physical performance, particularly concerning road travel on matchdays.



#10 In-season autoregulation of one weekly strength training session maintains physical and external load match performance in professional male football players

Reference: J Sports Sci. 2023 Jun 21;1-11. doi: 10.1080/02640414.2023.2227536. Online ahead of print.

Authors: Per Thomas Byrkjedal, Atle Thunshelle, Matt Spencer, Live Steinnes Luteberget, Andreas Ivarsson, Fredrik Tonstad Vårvik, Koldbjørn Lindberg, Thomas Bjørnsen

Summary: The aim of this study was to compare the effects of autoregulating strength training volume based on an objective (external load match performance) versus a subjective (self-selected) method in professional male football players. Sixteen players completed a 10-week strength training programme where the number of sets was regulated based on football match high-intensity running distance (HIR >19.8 km/h, AUTO, n = 7), or self-selected (SELF, n = 9). In addition to traditional physical performance assessments (30-m sprint, countermovement jump, leg-strength, and body composition), external load match performance was assessed with five matches in the beginning and in the end of the study period. Both groups performed ~ 1 weekly bout of ~ 6 sets in leg extensor exercises during the 10-week period, and maintained physical performance during the competitive season, with no group differences detected after the training period. Non-overlap of all pairs (NAP) analysis showed weak-to-moderate effects in external load match performance from before to after the study period, suggesting that players maintained or improved their performance. In conclusion, no group differences were observed, suggesting that both external load autoregulated and self-selected, low-volume in-season strength training maintained physical, and external load match performance in professional male football players.



#11 The effect of progressive and individualised sport-specific training on the prevalence of injury in football and handball student athletes: a randomised controlled trial

Reference: Front Sports Act Living. 2023 Jun 6;5:1106404. doi: 10.3389/fspor.2023.1106404. eCollection 2023.

Authors: Cathrine Nyhus Hagum, Espen Tønnessen, Jonny Hisdal, Shaher A I Shalfawi

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Summary: The aim was to evaluate the effectiveness of communication and coordination combined with designing a progressive and individualised sport-specific training program for reducing injury prevalence in youth female and male football and handball players transitioning to a sports academy high school. An additional aim was to investigate the characteristics of the reported injuries. Forty-two Norwegian athletes were randomised into an intervention or control group. Mean age, height, weight and BMI was 15.5 ± 0.5 years, 178.6 cm ± 6.3 cm, 71.3 ± 9.8 kg, 22.3 ± 2.7 BMI for the intervention group (IG) (n = 23), and 15.4 ± 0.5 years, 175.6 cm ± 6.6 cm, 67.1 ± 9.8 kg, 21.7 ± 2.4 BMI for the control group (CG) (n = 19). During the summer holiday, the intervention group received weekly progressive, individualised sport-specific training programs and weekly follow-up telephone calls from the researchers. All athletes completed a baseline questionnaire and a physical test battery. Training data and injuries were recorded prospectively for 22 weeks using the Oslo Sports Trauma Research Center Questionnaire on Health Problems (OSTRC-H2). A two-way chi-square (χ2) test of independence was conducted to examine the relationship between groups and injury. Average weekly prevalence of all injuries was 11% (95% CI: 8%-14%) in IG and 19% (95% CI: 13%-26%) in CG. Average weekly prevalence of substantial injuries was 7% (95% CI: 3%-10%) in IG and 10% (95% CI: 6%-13%) in CG. The between-group difference in injuries was significant: χ2 (1, N = 375) = 4.865, p = .031, φ = .114, with 1.8 times higher injury risk in CG vs. IG during the first 12 weeks after enrolment. For student athletes transitioning to a sports academy high school, progressive individualised, sport-specific training programs reduced the prevalence of all-complaint injuries following enrolment. Clubs and schools should prioritise time and resources to implement similar interventions in periods where student athletes have less supervision, such as the summer holidays, to facilitate an optimal transition to a sports academy high school.



#12 Insurance cost and injury characteristics of anterior cruciate ligament injuries in sub-elite football: A population analysis involving 3 years of Australian insurance data

Reference: J Sci Med Sport. 2023 Jun 9;S1440-2440(23)00129-9. doi: 10.1016/j.jsams.2023.06.003.

Authors: Andrew G Ross, Marnee J McKay, Evangelos Pappas, Kerry Peek

Summary: The aim was to investigate the injury characteristics and insurance cost of anterior cruciate ligament injuries in sub-elite football players in New South Wales, Australia. Three years of insurance records (2018-2020) was used to describe anterior cruciate ligament injury costs and characteristics. Concomitant injuries and the mechanism of injury were determined by analysing the injury descriptions. Claim characteristics and costs are presented by age group (junior = 7-17 years, senior = 18-34 years, and veteran = 35 + years) and sex. Categorical data (including age-groups and sex) are presented as counts and percentages and analysed using a Chi squared or Fisher's exact test. Cost data are reported as means ± standard deviation with 95 % confidence intervals. Over the course of three football seasons (2018-2020), 786 anterior cruciate ligament injuries were reported to the injury insurance company. The total insurance cost was AU$3,614,742 with direct injury insurance costs accounting for 36.3 % of the total costs. The mean indirect insurance costs were six-fold higher than direct insurance costs (AU$11,458 vs AU$1914). Isolated injuries had an average cost of $4466 whilst concomitant injuries had an average cost of $4951. Surgical costs are excluded from direct cost calculations. The peak injury count occurred in the first month of all three football seasons, immediately after the pre-season. Anterior cruciate ligament injuries represent a substantial economic burden to the insurer and individual. The cost data provided can be used for future economic and modelling studies.



#13 Are Metabolic Power Distribution and Accelerometer-Based Global Positioning System Variables Associated With Odds Ratios of Noncontact Injuries in Professional Soccer Players?

Reference: J Strength Cond Res. 2023 Jun 29. doi: 10.1519/JSC.0000000000004475. Online ahead of print.

Authors: Hadi Nobari, Ana Ruivo Alves, Hamed Abbasi, Davood Khezri, Angel Denche Zamorano, Thomas G Bowman

Summary: The present study was intended to i) investigate the relationship between metabolic power average (MPA), acceleration (AcZ) and deceleration (DcZ) zones, and their differences (Δ) on 3 load levels with noncontact injuries in professional players throughout a full soccer season and ii) to analyze the injury risk associated between high-load versus low-load levels for each of the aforementioned parameters with odds ratios (OR) and relative risk (RR), respectively. Twenty-one professional soccer players (age = 28.3 ± 3.9 years) were monitored during a full season (48 weeks) through global positioning system (GPS). A relationship between MPA and accelerometer-based GPS, mainly in explosive actions (i.e., AcZs and DcZs), was found. A higher incidence of injuries in the high-load weeks compared with the low-load weeks were reported (mainly in MPA, AcZ1, AcZ2, and DcZ3 variables). Moreover, significant means of OR (mean = 4.3) and RR (mean = 2.6) of noncontact injuries were established in intense periods with higher metabolic load (i.e., power accelerations, AcZ1, x2 = 0.022). Our results may be useful for coaches, sports scientists, and researchers regarding the optimization of the athletes' performance, as well as providing insights about the impact of intense exercise.



#14 Reduction in Substance-Related Composite Harm Scores Through Street Soccer

Reference: Cureus. 2023 May 29;15(5):e39650. doi: 10.7759/cureus.39650. eCollection 2023 May.

Authors: Alan T Bates, Lurdes Tse-Agha, Arun Agha, John-Jose Nunez, Heidi N Boyda, Andrea A Jones, Alasdair M Barr, William G Honer, Fidel Vila-Rodriguez

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Summary: Introduction Street soccer makes the sport accessible to people affected by homelessness or precarious housing. There is overwhelming evidence that exercise improves physical and mental health. In addition, sport facilitates positive peer pressure that leads to beneficial life changes. Method To examine participants' accounts of the effects of street soccer in a sample of socially disadvantaged players from Western Canada, we collected 73 cross-sectional self-reports of life changes via a questionnaire. The questionnaire included questions on social, mental, and physical health, including substance use. This allowed the calculation of a modified composite harm score. Results Participants reported improved physical (46% of participants) and mental (43% of participants) health, reduced cigarette (50% of smokers), alcohol (45% of users), cannabis (42% of users), and other non-prescribed drug use, increased number of friends (88% of participants), improved housing (60% of participants), increased income (19% of participants), increased community medical supports (40% of participants), and decreased conflicts with police (47% of those with prior recent conflict). Perceived reductions in substance use were supported by significant changes in composite harm score. Conclusion Street soccer appears to promote improved physical, mental, and social health among people affected by homelessness or precarious housing, with reduction in substance use likely to be a key factor. This work builds upon past qualitative research showing the benefits of street soccer and supports future research which may help elucidate the mechanisms by which street soccer has beneficial effects.



#15 Assessment of stress response and its interrelationship with external load in female soccer players

Reference: Ann Agric Environ Med. 2023 Jun 26;30(2):348-351. doi: 10.26444/aaem/163631. Epub 2023 May 10.

Authors: Yang Xing, Tailai Zhang, Andriy V Gorkovenko, Tetiana Abramovych, Andriy Maznychenko, Inna Sokolowska

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Summary: The study aimed to evaluate the physiological stress response, i.e. internal load to intermittent and continuous exercise performed during the treadmill running in professional female soccer players, and additionally to determine the most appropriate method for assessing load in the athletes. Six professional female athletes (age 25.3±1.8 years, height 168.4±2.7 cm, weight 64.8±5.8 kg, maximal oxygen consumption (V˙ O2max) 64±4.1 ml۰kg-1۰min-1, and heart rate (HRmax) 195±1.8 b.p.m.) performed a series of preseason treadmill tests. HR and V˙ O2max were measured in the athletes during intermittent load (increase and decrease of running time and treadmill speed) and an incremental load (gradual increases running time, treadmill speed and a treadmill incline angle). Banister's, Edwards', Stagno's and Lucia's training impulse (TRIMP) quantification methods were used to assess internal load. The relationships between V˙ O2max and above-mentioned TRIMPs load indicators were calculated using Pearson's correlation coefficient. Large, very large and near perfect correlations between TRIMP and V˙ O2max were observed during intermittent and incremental load (range r = 0.712 - 0.852 and r =563 - 930; p < 0.05, respectively). Correlations between other TRIMPs and V˙ O2max demonstrated moderate, small and negative small relationships. Changes in HR and oxygen consumption registered during intermittent or gradually increasing load conditions could be evaluated using the TRIMP method for both types of activities, and this method could potentially be useful for the testing of high-intensity intermittent physical fitness of players before the soccer season.


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