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From Reparation to Competitive Period in Soccer: Hematological Changes

Authors:
  • National and Kapodistrian University of Athens,
Article

From Reparation to Competitive Period in Soccer: Hematological Changes

Abstract

Hematological parameters affect the aerobic capacity which is considered as basic for technical and tactical development of soccer players. However, the hematological parameters such as hemoglobin (HBG), hematocrit (HCT), red blood cells (RBC), iron status and ferritin concentration, change throughout a season. Therefore, the current longitudinal study aimed to examine the changes of hematological parameters in professional soccer players throughout a 6-month period. The researchers examined 25 soccer players (25.7 ± 2.1) at the beginning of the preparation period, at the middle, and at the end of the preparation period, as well as at the competitive period. The results indicated that in the first part of the preparation period there was an increasing trend for all the hematological parameters. This trend developed significant increases at the end of the preparation period, which corresponds at the beginning of the competitive period. In summary, the current findings showed that the players improve and maintain their hematological values throughout the season because of aerobic training during preparation period.
Sport Science Review, vol. XXIV, No. 1-2, April 2015
103
From Preparation to Competitive
Period in Soccer:
Hematological Changes
Evangelos BEKRIS1 • Aristotelis GIOLDASIS1 • Ioannis GISSIS2
Konstantinos ANAGNOSTAKOS3 • Mylonis ELEFTHERIOS1
Hematological parameters affect the aerobic capacity which is
considered as basic for technical and tactical development of
soccer players. However, the hematological parameters such as hemoglobin
(HBG), hematocrit (HCT), red blood cells (RBC), iron status and ferritin
concentration, change throughout a season. Therefore, the current
longitudinal study aimed to examine the changes of hematological parameters
in professional soccer players throughout a 6-month period. The researchers
examined 25 soccer players (25.7 ± 2.1) at the beginning of the preparation
period, at the middle, and at the end of the preparation period, as well as
at the competitive period. The results indicated that in the rst part of the
preparation period there was an increasing trend for all the hematological
parameters. This trend developed signicant increases at the end of the
preparation period, which corresponds at the beginning of the competitive
period. In summary, the current ndings showed that the players improve
and maintain their hematological values throughout the season because of
aerobic training during preparation period.
Keywords: soccer players, hematological parameters
1 Department of Physical Education and Sport Science, National and Kapodistrian University of Athens,
Greece
2 Department of Physical Education and Sport Science, Serres Aristotle University of Thessaloniki,
Greece
3 A΄Orthopaedic Department, General Hospital of Athens “KAT”, Greece
ISSN: (print) 2066-8732/(online) 2069-7244
© 2015 • National Institute for Sport Research • Bucharest, Romania
Sport Science Review, vol. XXIV, no. 1-2, 2015, 103 - 114
DOI: 10.1515/ssr-2015-0011
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Introduction
Research ndings conclude that long-term regular exercise affect positively
features such as physical, physiological and psychological parameters of human
organisms (Ban et al., 2006; Fox et al., 1999; Manna et al., 2010; Schumacher
et al., 2002; Thiago Santi et al., 2013). Very important effects are observed on
hematological parameters which have been found to inuence the physical
performance of players (Manna et al., 2010; Schumacher et al., 2002; Thiago
Santi et al., 2013). A game that requires well developed physical and physiological
capacities is soccer. It is widespread called as the game of stamina and techniques.
In addition, studies conclude that both technical and tactical skills are highly
dependent on the physical capacity of the players (Hoff et al., 2002). Therefore,
it is essential to examine how these factors change throughout an entire season.
The most common hematological variables linked to the aerobic capacity are
hemoglobin (HBG), hematocrit (HCT), red blood cells (RBC), iron status and
ferritin concentration.
Hemoglobin values determine the oxygen transport and consumption
(Kanstrup & Ekblom, 1984; Kuipers et al., 2007; Martino, et al., 2002; Nielsen
& Weber, 2007; Suhr et al., 2009) which is linked to physical performance
(Saltin et al., 1992) through aerobic capacity (Śliwowski et al., 2011). Regarding
longitudinal measurements of HBG it has been found that a 3-month soccer
training program increase HBG values (Silva et al., 2008). In contrast Manna and
colleagues (2010) concluded that their 3-month soccer training program reduce
HBG values. Ban and colleagues (2006) also added that HBG is decreased
during the more intense periods of training. Moreover, it has been found
that HBG values were higher at the beginning of the competitive season, and
then declined for the well-trained soccer players (Malcovati et al., 2003). On
the other hand Ostojic and Ahmetovic (2009) found that HBG was unaltered
through the season. Concerning changes before and after a training session it
has been found that HBG levels were signicantly increased (McGuire, 2012).
Concerning hematocrit level, it is usually associated with enhancement of the
oxygen transport capacity of the blood and the aerobic performance, while an
increase of HCT raise the values of blood viscosity (Hu et al., 2008). Soccer
players present higher levels of HCT than the non-athletes (Joksimović et al.,
2009; Nikolaidis et al., 2003). According to Silva and colleagues (2008) HCT was
signicantly increased after a 3-month training program while it is decreased
during the more intense periods of training (Ban et al., 2006). Malcovati and
colleagues (2003) expressed that HCT values were higher at the beginning of
the competitive season, and then declined for the well-trained soccer players.
Similarly, Ostojic and Ahmetovic (2009) concluded that HCT was higher at the
preparation period. The main function of red blood cells is the oxygen transport
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Sport Science Review, vol. XXIV, No. 1-2, April 2015
105
and consumption (Mairbäurl, 2013). It has been found that they are affected
by training (Joksimović et al., 2009). Research ndings in soccer have shown
that throughout a 3-months training program RBC were signicantly increased
(Mairbäurl, 2013; Silva et al., 2008). Iron through serum ferritin concentration
is also connected to physical performance and VO2max. Ostojic and Ahmetovic
(2009) after a longitudinal study concluded that iron status indicators were stable
and poorly related to training phase during sports season. Concerning changes
before and after training sessions it has been found that iron stores and serum
levels were signicantly decreased (McGuire, 2012). In contrast, other studies
indicate that exercise does not affect the hematology variables (Spiropoulos &
Trakada, 2003; Akgün, 1994).
The literature review obviously showed that although regular exercise affects
blood hematology (i.e. Koç et al., 2010) there is a conict regarding the effects
of exercise’s duration, severity and frequency (Baltacı et al., 1998; Büyükyazı &
Turgay, 2000; Shephard & Shek, 1994). Additionally, last decades the amount of
high intensity running has increased (Mohr et al., 2003) nding that probably
changes the physiological demands throughout the season. Indicatively, some
factors that affect hematological parameters are sport, sex, nutrition, training,
and age (Bezci & Kaya, 2010; Ostojic & Ahmetovic, 2009; Savucu, 2012;
Schumacher et al., 2002; Thiago Santi et al., 2013). Thus, the current longitudinal
study aimed to examine the changes of hematological parameters in professional
soccer players throughout a 6-month period.
Methods
Participants
The participants of the study were twenty ve professional soccer players
aged 25.7 ± 2.1. A weighting scale (BC1000, Tanita, Japan ) and a height cursor
were used to measure the weight 72.8 ± 2.5 and the height 176.3 ± 3.3 of
the participants at the beginning of the preparation. The participants were
nonsmokers, without any metabolic disease during the study period. The
university research ethics committee granted approval for the study before
giving the players an informed consent document to sign. The researchers also
notied the players regarding requirements, benets, and risks of the study.
Procedures
The selected hematological parameters were examined in the laboratory
with a constant temperature (23-25oC) at the beginning of the preparation pe-
riod (BP) at the middle (MP), and at the end of the preparation period (EP), as
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well as at the competitive period (CP). The periods between the measurements
were four weeks between July and September, four weeks between September
and October, ten weeks between October and December. All the measurements
were scheduled at the same time of the day (from 08:30 to 09:30 am) in line
with hygiene rules. Blood samples (10ml) were collected by venipuncture from
the forearm vein in tubes with anticoagulant (EDTA K3) incorporated in its
walls and then analyzed in blood counting device. The players did not partici-
pate in any high intensity training program 48 hours before the measurements.
Statistical analysis
All the hematological variables were expressed as mean (M) and standard
deviations (SD) for all the measurements of the study. The researchers
performed analysis of variance for repeated measures (ANOVA) to examine the
changes between the measurements and bonferroni correction tests to nd out
the signicant differences between groups. The SPSS package (v. 17) was used
to perform all the statistical analyses.
Results
The following table (Table 1) shows the descriptive statistics and bonferroni
tests of hematological parameters of all the measurements. It is obvious that
Bonferroni correction tests indicated that the mean score of hemoglobin in BP
was signicantly lower than EP (P< .5). Similarly, the mean score of hematocrit
in BP was signicantly lower than EP (P< .5). Bonferroni correction tests
indicated that the mean score of red blood cells in BP was signicantly lower
than EP (P< .05). In contrast the mean score of red blood cells in EP was
signicantly higher than CP (P< .10). Iron concentration in BP was signicantly
lower than EP (P< .05). Finally, ferritin concentration in BP was signicantly
lower than MP (P< .05), while it was signicantly lower in EP than CP (P< .05).
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Table 1
Descriptive statistics and bonferroni tests of hematological variables
Discussion
The study examined the Greek professional soccer players because there
was a conict in the results regarding changes of hematological parameters
throughout a long-term period. The results indicated that although hemoglobin
values were increased throughout the 6-month period the only signicant change
was from BP to EP, nding that was also supported by the literature review (Silva
et al., 2008; Ünal, 1998). However, many studies suggest that hemoglobin levels
are decreased because of haemolysis and hemodilution (Böning et al., 2007;
Kargotich et al., 2007; Neumayr et al., 2005; Suhr et al., 2009). Similarly, although
hematocrit values were increased from BP to EP the only signicant change was
between BP and EP. In contrast, the value was reduced in the period EP- CP.
The literature review showed that although hematocrit values were higher at
the beginning of the season then they declined (Malcovati et al., 2003; Ostojic
& Ahmetovic, 2009). It is known that after long term exercise several factors
such as adaptation of exercise, cardiovascular, physical, physiological affect
the hematological parameters (Bijeh et al., 2013). The nding concerning the
decrease of hematocrit is probably explained by the plasma volume expansion
during the competitive season (Shaskey & Green, 2000). A possible explanation
for the current ndings is that the players were not physically exhausted whereas
several past ndings suggest that any reduction of hemoglobin and hematocrit
values is a sign of physical exertion and heavy participation (Fallon et al., 1999;
Malcovati et al., 2003; Rietjens et al., 2002). Concerning the values of red blood
cells it was found an increasing trend from BP to EP, while it was reduced from
EP to CP. However the only signicant ndings were the increase of red blood
cells between BP and EP and their reduction between EP and CP. The literature
review (Koç et al., 2012; Mairbäurl, 2013; Silva et al., 2008) supports the RBC
increase throughout a period as they are affected by training (Joksimović et al.,
Measurements Variables
Hemoglobin Hematocrit Red blood cells Iron status Ferritin
concentration
BP114.41 (.16) 43.10 (.46) 4.93 (.06) 66.05 (4.05) 45.92 (6.12)
MP214.56 (.13) 44.07 (.41) 5.06 (.08) 76.12 (4.71) 69.20 (5.99)
EP315.01 (.14) 45.17 (.42) 5.27 (.07) 93.27 (5.05) 61.52 (5.12)
CP415.07 (.15) 43.68 (.45) 5.00 (.06) 93.79 (4.98) 109.10 (12.52)
Bonferroni 1<3 1<3 1<3; 3>4 1<3 1<2; 3<4
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2009). This increase is also linked to oxygen transport as the young cells of RBC
are more efcient in this procedure (Smith, 1995). The results indicated a trend of
iron status to be increased throughout the period. However, the only signicant
increase was between BP and EP. This increase was in contrast to the literature
review that concluded a stability of iron status (Ostojic & Ahmetovic, 2009)
and even a decrease of this (McGuire, 2012). Finally, ferritin concentration was
signicantly increased from BP to MP, as well as from EP to CP. Past literature
showed that ferritin values were reduced because of training (McGuire, 2012).
However, these ndings are not about longitudinal changes but only before and
after training changes. The indicators of hematological parameters are directly
linked to the intensity and duration of training and therefore it should be deeper
considered (Schumacher et al., 2000; Thiago Santi et al., 2013). In total, any
conict in the results is probably explained by many factors such as the age, the
nutrition and the training (Bezci & Kaya, 2010; Ostojic & Ahmetovic, 2009;
Savucu, 2012; Schumacher et al., 2002; Thiago Santi et al., 2013).
Conclusion
In summary, the current study shows that in the rst part of the preparation
period there was an increasing trend for all the hematological parameters. This
trend developed signicant increases during EP, which corresponds at the
beginning of the competitive period. This is probably explained by the aim to
improve the aerobic capacity of the players throughout the training sessions
of the preparation period. It is also explained by homogeneity that the sample
developed because of the similar program which all the players followed (training
sessions, friendlies). On the other hand, the decreased volume and increased
intensity of the competitive period modied the values of hematological
parameters. In addition, a possible cause for hematological changes in CP was
probably the different playing time of each player. Therefore, it is obvious that
soccer coaches have to evaluate the effectiveness of their training plans for each
player individually during the whole season through hematological measurements
so as to achieve the best performance.
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Evangelos BEKRIS, Dr., Msc. is currently an associate professor of soccer coaching
at the Kapodistrian University of Athens. He earned his PhD in Biochemistry at the
Kapodistrian University of Athens. He began his research career examining the effect
of exercise on health of youth. His research interests include soccer coaching, match
analysis, biomechanics, fatigue and talent identication. He publishes regularly books
and papers about soccer and medical issues. He can be contacted: vag_bekris@yahoo.gr
Aristotelis GIOLDASIS is currently a PhD student at the Faculty of Human Movement
and Quality of Life Sciences, University of Peloponnese in Sparta. He earned his Master
of Science degree in Sport Psychology at the Kapodistrian University of Athens. He began
his research career examining psychological factors that inuence soccer performance.
His current research interests include physiological, biochemical and psychological
effects on performance. He publishes regularly in international sport sciences journals.
Corresponding address:
Aristotelis Gioldasis
Lachana 14-16
11362 Athens
Greece
Email: giold_telis@yahoo.gr
Phone: +306906511661
Ioannis GISSIS, PhD is currently an assistant professor in soccer coaching/training
at Aristotle University of Thessaloniki, Greece. He earned his PhD in Social Sciences
(Sports Science) at Eberhard Karls University Tuebingen, Germany. His research
interests include analysis and training of soccer technique, evaluation and training of
soccer physical tness, evaluation and training of soccer physical tness in childhood
and adolescence, evaluation and training of physical tness. He can be contacted at:
igkisis@phed-sr.auth.gr
Konstantinos D. ANAGNOSTAKOS is a senior registrar doctor at KAT hospital
(traumatology center in Athens). Previous experience: Trainee doctor in General Hospital
of Kimi, Central Greece (2006-2007); Resident doctor of General Surgeon Practice
in General Hospital of Leros, Greece (2008-2009); Resident doctor of orthopaedics
in General Hospital of Karpenisi (2009-2012); Resident & Senior Resident doctor in
General Hospital of Athens KAT (2012 - present). His medical school was the “Grigore
T. Popa” University of Medicine & Pharmacy, Iasi, Romania (1996-2002). He has a MCs
in “Emergency medicine” at the University of Athens. His current research area and
his experience as surgeon is in sport medicine. He can be contacted at: drkostasa2002@
yahoo.gr
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Eleftherios MYLONIS, Msc is currently teacher of physical education and physical
trainer in soccer professional teams. He earned his degree within the Department of
Physical Education and Sport Science, National and Kapodistrian University of Athens
and his Msc in Physical Fitness within the Department of Physical Education and Sport
Science, National and Kapodistrian University of Athens with thesis titled “Longitudinal
Variability of Fitness Parameters of Greek Professional Soccer Players. He began his
research career examining the effect of small sided games (Supernumerary in small sided
games 3Vs3 & 4Vs4, The Physiological and Technical-Tactical Effects of an Additional
Soccer Player’s Participation in Small Sided Games Training). His current research areas
include soccer technical and fatigue subjects (the effects of practicing with a size-2 ball
on the technical skills of young soccer players of a different level; the effects of fatigue
in small-sided games work outs).
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... Besides the common influencers of aerobic fitness (e.g., ventilatory kinetics, cardiac process, neuromuscular status), other hematological and biochemical parameters assume a preponderant role in athletes' performance [22]. However, there is incongruent evidence regarding the effects of acute and/or chronic training stimulus on hematological parameters, such as hemoglobin (Hb), red blood cells (RBC), and hematocrit (Ht) [23]. It seems that there is a trend to observe increases in the above-mentioned hematological parameters after a period of soccer training, especially during the preparation phase [24]. ...
... It seems that there is a trend to observe increases in the above-mentioned hematological parameters after a period of soccer training, especially during the preparation phase [24]. The Hb, RBC, and Ht are important hematological parameters since they are linked to the player's aerobic capacity, which is one of the physical aspects most trained during the pre-season [23,25]. In the case of biochemical parameters, they represent an important role for the monitoring of an athlete's responses to the training loads imposed [26]. ...
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Citation: Clemente, F.M.; González-Fernández, F.T.; Ceylan, H.I.; Silva, R.; Younesi, S.; Chen, Y.-S.; Badicu, G.; Wolański, P.; Murawska-Ciałowicz, E. Blood Biomarkers Variations across the Pre-Season and Interactions with Training Load: A Study in Professional Soccer Players. J. Clin. Med. 2021, 10, 5576. https://doi.
... The preparation period increases the soccer player's hematological parameters because of aerobic capacity improved. Eventually, researchers recommended that to achieve the best performances of players, coaches should measure the hematology of players (Anagnostakos et al., 2015). ...
... we did not find any significant differences in those variables. According to Anagnostakos et al. (2015), hematological variables such as RBC, HGB, HCT, iron concentration, and ferritin concentration determine aerobic capacity and skill improvement of football players. The objectives of the study were to test the effects of six-month training on hematological variables of soccer players. ...
... It is well known that most common hematological measurements (e.g., plasma volume [PV], hemoglobin [Hb], hematocrit [Ht], and red blood cells [RBC] count) are linked to the development of aerobic capacity [7]. Previous research suggested that intensive physical stress affects PV and hematological parameters, which may negatively influence players' physical performance [8,9]. ...
... Thus, it seems beneficial to monitor soccer players' Hb and Ht parameters. Several studies showed decreases in Hb and Ht values after periods of intense training or competition [6,7,26]. These declines are known as an adaptation to training and called sports pseudo-anemia [29,6]. ...
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Objectives: The aims of this study were to investigate the effects of a six-week in-season period of soccer training and games (congested period) on plasma volume variations (PV), hematological parameters, and physical fitness in elite players. In addition, we analyzed relationships between training load, hematological parameters and players' physical fitness. Methods: Eighteen elite players were evaluated before (T1) and after (T2) a six-week in-season period interspersed with 10 soccer matches. At T1 and T2, players performed the Yo-Yo intermittent recovery test level 1 (YYIR1), the repeated shuttle sprint ability test (RSSA), the countermovement jump test (CMJ), and the squat jump test (SJ). In addition, PV and hematological parameters (erythrocytes [M/mm3], hematocrit [%], hemoglobin [g/dl], mean corpuscular volume [fl], mean corpuscular hemoglobin content [pg], and mean hemoglobin concentration [%]) were assessed. Daily ratings of perceived exertion (RPE) were monitored in order to quantify the internal training load. Results: From T1 to T2, significant performance declines were found for the YYIR1 (p<0.001, effect size [ES] = 0.5), RSSA (p<0.01, ES = 0.6) and SJ tests (p< 0.046, ES = 0.7). However, no significant changes were found for the CMJ (p = 0.86, ES = 0.1). Post-exercise, RSSA blood lactate (p<0.012, ES = 0.2) and PV (p<0.01, ES = 0.7) increased significantly from T1 to T2. A significant decrease was found from T1 to T2 for the erythrocyte value (p<0.002, ES = 0.5) and the hemoglobin concentration (p<0.018, ES = 0.8). The hematocrit percentage rate was also significantly lower (p<0.001, ES = 0.6) at T2. The mean corpuscular volume, mean corpuscular hemoglobin content and the mean hemoglobin content values were not statistically different from T1 to T2. No significant relationships were detected between training load parameters and percentage changes of hematological parameters. However, a significant relationship was observed between training load and changes in RSSA performance (r = -0.60; p<0.003). Conclusions: An intensive period of "congested match play" over 6 weeks significantly compromised players' physical fitness. These changes were not related to hematological parameters, even though significant alterations were detected for selected measures.
... Hematological parameters (e.g. hemoglobin and hematocrit) and plasma volume variation (PVV) may be considered as a valuable marker in the evaluation of aerobic capacity development [17][18][19]. Indeed, the increase of PVV is associated with an increase of aerobic performances (e.g. ...
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Aim To evaluate the effects of eight weeks of mat Pilates training on selected hematological parameters, i . e . white blood cell, neutrophils, monocyte, lymphocyte, hematocrit, hemoglobin as well as plasma volume variations in healthy, active women. Methods Twenty-eight women physical education students volunteered to participate in the present investigation. They were assigned to two groups: a Pilates training group (n = 14) that followed an 8-week Pilates training program, and a control group (n = 14). Blood samples were collected at rest at two separate occasions before and after Pilates training. Results The Pilates training group had higher values of plasma volume variations and lower values of white blood cell (19.4%), neutrophils (32%), hematocrit (4.3%) and hemoglobin (4.6%) compared to control group (p<0.05). Conclusion The results of the present study suggested that Pilates training could be an effective strategy for increasing plasma volume variations and boosting immune system in healthy active women.
... For instance, the reduced aerobic performance might be partly caused by an increased Ht and Hb concentration, showing a blood hemoconcentration adaptation [19]. ose measures may assume an even important role regarding their changes during the PS phase, as the aerobic capacity is intended to positively improve [20]. As in high-performance context, the athletes are subjected to tight schedules, coaches and practitioners have to plan recovery strategies to prevent injury or illness [21]. ...
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Background: Physical conditions are recognized to be optimal after the pre-season (PS) phase in professional sports. Given that blood measures may also reveal variations, which in turn, may present associations with fitness changes. Objective: The aim of this study is to test the changes of blood markers and physical fitness outcomes at the beginning and following the PS phase. Additionally, we aimed also to analyze the associations of training adaptations between blood markers and the physical fitness measures. Methodology. 25 professional male soccer players (28.1 ± 4.6 years old, 2.0 ± 7.8 kg, and 176.7 ± 4.9 cm) were assessed for hematological and biochemical parameters, and physical fitness measures in the baseline and after the phase of PS. Results: Increases in platelets were observed after the PS phase (p = 0.001, η2 = 0.39). Regarding the biochemical parameters, significant increases between PS were found for creatinine (Cre) (p = 0.001, η2 = 0.66), alkaline phosphatase (ALP) (p = 0.001, η2 = 0.79), C-Reactive Protein (CRP) (p = 0.001, η2 = 0.74), cortisol (C) (p = 0.001, η2 = 0.63), and testosterone (T) (p = 0.001, η2 = 0.76), whereas significant decreases were found for albumin (Alb) (p = 0.004, η2 = 0.29), and calcium corrected (Ca Corr.) (p = 0.002, η2 = 0.32). Moderate correlations were found between albumin and the 5-meter linear sprint split (r = -0.44 (95%CI: -0.71; -0.05)) and CRP (r = -0.48 (95%CI: -0.74; -0.10)). Moderate correlations were found between VAMEVAL and hemoglobin (r = 0.44 (95%CI: 0.05; 0.71)). Conclusions: The overall physical fitness measures improved after the PS phase. Also, significant variations (decreases/increases) were observed for the case of biomchemical and hematological outcomes. Coaches should carefully consider the adaptative changes observed in blood parameters as the changes in whole organism and metabolism after specific critical phases as the PS in professional players. Thus, optimal management of stimulus/recovery can be warranted to minimize illness and injury rate and to follow the direction and dynamics of adaptative changes.
... Thus, it seems beneficial to monitor football players' Hb and Ht parameters. Several studies showed decreases in Hb and HT values after periods of intense training or competition [25]. These declines are known as an adaptation to training [26]: erythrocytosis during exercise induces an increase in the absolute concentration of Hb [16], but this mechanism is masked by a rise in plasma volume (PV) [27]. ...
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This prospective cohort study aimed to evaluate whether COVID-19 lockdown caused biological, psychological, and/or physical performance variations in footballers. We compared the 2018/2019 and 2019/2020 seasons evaluating the plasma volume, hematological parameters, iron/ferritin, creatine kinase, vitamin D, cortisol, testosterone, and physiological state of players of the Italian football major league (Serie A). Measurements were performed before the preparatory period (T0), at the beginning (T1) and in the middle (T2) of the championship, and in March (T3) and at the end of season (T4). The results showed that in the 2019/2020 season affected by the lockdown, the weight, BMI, and fat mass percentage were higher than in the previous season. Hematocrit, hemoglobin, red blood cells, and ferritin decreased during both seasons, more significantly than in the regular season. During both seasons, creatine kinase increased from T2 whilst iron concentrations decreased in T3. Testosterone increased in both seasons from T0 to T3 and returned to initial levels at T4; cortisol increased in T2 and T3 during the 2018/2019 season but not during the COVID-19 season. Physical performance tests revealed differences associated with lockdown. Thus, although from a medical point of view, none of the evaluated changes between the two seasons were clinically relevant, training at home during lockdown did not allow the players to maintain the jumping power levels typical of a competitive period.
... In fact, increases in hemoglobin levels are related to a greater aerobic performance due to the better oxygen transport capacity (Otto et al., 2013). Several studies reported declines in hemoglobin levels in professional soccer players after periods of high-intensity activity (Silva et al., 2008;Bekris et al., 2015). Given that, monitoring hemoglobin levels can be useful for assessing SSGs intensity. ...
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The purposes of this study were (1) to analyze between-session variations of external and internal load measures during small-sided games (SSGs) and (2) to test the relationships between the maximum speed reached (V IFT) during the last stage of the 30-15 Intermittent Fitness Test, hemoglobin levels, and training load measures during SSG intervals among professional soccer players. Sixteen professional soccer players (mean ± SD; age 27.2 ± 3.4 years, height 174.2 ± 3.6 cm, body mass 69.1 ± 6.4 kg, and body fat 10.4 ± 4.1%) participated in this study. Hemoglobin and aerobic performance were first tested, and then a 3-week SSG program was applied using a 3 vs. 3 format. During those 3 weeks, internal and external load of entire sessions were also monitored for all training sessions. Trivial-to-small, standardized differences were observed between sessions for external and internal measures during SSGs. Total distance (TD) and mechanical work (MW) were the only variables that indicated small changes. Large-to-very-large relationships were found between V IFT and external loads: TD (r range: 0.69; 0.87), high-intensity running (HIR; r range: 0.66; 0.75), and MW (r range: 0.56; 0.68). Moderate-to-large negative relationships were found between hemoglobin levels and internal loads: Edwards' TRIMP (r range: −0.36; −0.63), %HR max (r range: −0.50; −0.61), and red zone (r range: −0.50; −0.61). V IFT had unclear relationships with overall internal loads, while hemoglobin levels presented unclear relationships with overall external loads. In conclusion, no meaningful changes were found between sessions considering the format of play used. Additionally, the detected relationships indicate that V IFT and hemoglobin levels are good indicators of the performance capacity and physiological profile of players during SSGs. Also, the use of SSGs protocols as a monitoring complement of the 30-15 IFT is suggested.
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Workplace stress can be defined as the change in an individual's physical or mental state in response to workplaces that pose a challenge or threat to that employee (Colligan & Higgins, 2006). Teacher well-being has become increasingly important in understanding the contextual variables related to learners' academic, social-emotional, and behavioral growth (Von der Embse, 2021). Among teachers, physical education and sports teachers may suffer from stress due to high workloads. The purpose of the present study was to initially validate a stress measurement scale for physical education teachers in Tunisia.
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Short-duration pre-tournament training (SDPT) is a common training technique used to prepare for major competitive football tournament. There is scarcity of report on the effects of SDPT on the cardiovascular parameters of university footballers in Ghana. This study examined the changes in cardiovascular parameters of a-university footballers due to SDPT. Thirteen male footballers (mean age 21.23 ±1.73 years) who represented the Kwame Nkrumah University of Science and Technology in the Ghana University Sports Association’s competition in 2016 participated in the study. The players engaged in SDPT of moderate to high intensity training for 2 weeks. Blood pressure, heart rate, fasting plasma glucose, haemoglobin, red blood cells, haematocrit, mean cell volume, mean cell haemoglobin, mean cell haemoglobin concentration, white blood cells, neutrophils, lymphocytes, absolute content of leucocyte, erythrocyte and platelets were measured pre and post training. There were significance decreases in body mass index ( P = 0.002), haemoglobin ( P = 0.042), haematocrit ( P = 0.003) and white blood cells ( P = 0.017), while fasting plasma glucose ( P = 0.017) and platelets ( P = 0.004) increased significantly. SDPT predisposes a-university footballers to acute inflammatory responses. Appropriately designed training duration and intensity would prevent increase in fasting plasma glucose and improve cardiorespiratory performance in university footballers. Keywords: Cardiovascular, Body composition, Resistance, University Footballers
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The purpose of this study was to describe and compare hematologically elite football players during the competitive period according to playing positions and determines the prevalence of anemia. The subjects consisted of 38 professional footballers from a professional club in the National Football League First Division of Brazil. Six groups were formed for hematological comparison: (a) goalkeepers; (b) side defenders; (c) central defenders; (d) central midfielders; (e) side midfielders; and (f) attackers. Data collection began at the start of competition. The anthropometric, hematological, and VO2 max measures were carried out on the first day. To determine hematological parameters, fasting blood samples were taken from the cubital vein. The One-Way analysis of variance and the Bonferroni adjustment for multiple comparisons were used for statistical comparison between the footballers of different playing positions. No statistically significant differences were found among the playing positions in all three hematological parameters (red blood cell count, hematocrit, and hemoglobin). All players maintained strict compliance of balanced diets.
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This study was conducted in order to determine the influence of five-day handball competitions on hematological levels of male handball players. 12 elite male handball players with an average age of 22.16 +/- 1.85 years participated in this study on voluntary basis. Physical measurements including body height, body weight, body-mass index and body fat percentages and hematological levels of the handball players were analyzed before (BC) and after the competitions (AC). In order to determine hematological levels, blood samples with 5 ml EDTA (Ethylenediaminetetraacetic acid) were taken from the forearm ante-cubital area in line with hygiene rules before and after competitions, and erythrocyte, leucocytes and blood platelet parameters were analyzed in laboratory with using auto-analyzers. Measurement results were presented as average and standard deviation. Student T-test for dependant samples was used in order to make a comparison between BC and AC values. SPSS 13.0 Package software was used for data evaluation. P<0.05 value was considered to be significant. As a result of the study, the decrease in BC and AC values for body weight, body-mass index, body fat percentages, MCV, MCH, CH and LY and the increase in RBC and NE values were found significant. Conclusively, erythrocyte, leucocytes and blood platelet levels display different behaviors vis-a-vis acute competition-like exercises.
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Hematological Profile of Serbian Youth National Soccer Teams Soccer is one of the most widely played and complex sports in the world, where players need technical, tactical, and physical skills to succeed. Technical and tactical skills in soccer are highly dependent on the player's physical capacity. The selection, development and professional guidance of young players is a priority for many top soccer clubs in order to maintain their sporting and financial status. The aim of the present study was to determine hematological profile of youth national soccer teams and to compare the values of fifteen hematological parameters between 3 Serbian youth national teams (under 14, 15 and 16 years old), as well as between soccer players and nonathletes. 80 young soccer players and 30 non-athletes participated in the study. 15 hematologic parameters (WBC, RBC, HGB, HCT, PLT, MCV, MCH, MCHC, PDW, LYM%, MON%, GRAN%, LYM, MON, GRAN) were measured. In order to determine the significance of differences between the groups on a multivariate level a multivariate analysis of variance (MANOVA) was administered, and to test the differences between the groups on an univariate level a univariate analysis of variance (ANOVA) was applied. It was concluded that there is no significant difference in all the variables (WBC, Ly, Mo, Gr, PLT, HGB, HCT, etc), except RBC, probably due to age, androgen affection on erythropoesis, field positoning and diet. From a practical point of view, the clinician has to take into account not only age, but also training status of individuals when evaluating their blood tests.
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Hematological Parameters of Elite Soccer Players during the Competitive Period. JEPonline 2013;16(5):68-76. The purpose of this study was to describe and compare hematologically elite football players during the competitive period according to playing positions and determines the prevalence of anemia. The subjects consisted of 38 professional footballers from a professional club in the National Football League First Division of Brazil. Six groups were formed for hematological comparison: (a) goalkeepers; (b) side defenders; (c) central defenders; (d) central midfielders; (e) side midfielders; and (f) attackers. Data collection began at the start of competition. The anthropometric, hematological, and VO 2 max measures were carried out on the first day. To determine hematological parameters, fasting blood samples were taken from the cubital vein. The One-Way analysis of variance and the Bonferroni adjustment for multiple comparisons were used for statistical comparison between the footballers of different playing positions. No statistically significant differences were found among the playing positions in all three hematological parameters (red blood cell count, hematocrit, and hemoglobin). All players maintained strict compliance of balanced diets.
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MARTINO, M., N. GLEDHILL, and V. JAMNIK. High VO2max with history of training is primarily due to high blood volume. Med. Sci. Sports Everc., Vol. 34, No. 6, pp. 966-971, 2002. Purpose: To investigate the high VO2max observed occasionally in young men who have no history of training. Methods: blood volume (BV). maximal stroke volume (SVmax), maximal cardiac output (Q(max)), and related measurements (reported as mean +/-SEM) were studied in six men (mean age 20.0 +/- 0.5 yr) with no history of training, who all had a VO2max below 49 mL.kg(-1).min(-1) (LO group) and six age- and weight-matched men (mean age 19.5 +/- 0.5 yr) with no history of training, who all had a VO2max above 62.5 mL.kg(-1).min(-1) (HI group). Results: Compared with the LO groups the HI group had a higher SVmax (149 +/- 5 vs 102 +/- 5 mL), higher (28.9 +/- 0.9 vs 20.0 +/- 1.0 L.min(-1)) and higher BV (88.1 +/- 3.8 vs 76.7 +/- 0.9 mL.kg(-1)). The BV of four participants in the HI group (mean = 92.3 +/- 4.3 mL.kg(-1)) was substantially higher than the BV of all participants in the LO group, but two participants in the HI group had a BV (mean = 79.7 +/- 0.8 mL.kg(-1)) that was similar to the mean BV of the LO group. Conclusion: The primary explanation for the high VO2max observed occasionally in young men who have no history of training is a naturally occurring (perhaps genetically determined) high BV that brings about a high SVmax and Q(max). However, some young men with no history of training have a high VO2max, and Q(max) possibly because a greater portion of their BV is hemodynamically active.
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This study aimed to quantify the hemolytic responses of elite female football (soccer) players during a typical weekly training session. Ten elite female football players (7 field players [FPs] and 3 goalkeepers [GKs]) were recruited from the Australian National Women's Premier League and asked to provide a venous blood sample 30 min before and at the immediate conclusion of a typical weekly training session. During this training session, the players' movement patterns were monitored via a 5-Hz global positioning system. The blood samples collected during the training session were analyzed for iron status via serum ferritin (SF) analysis, and the hemolytic response to training, via serum free hemoglobin (Hb) and haptoglobin (Hp) measurement. 50% of the participants screened were found to have a compromised iron stores (SF<35 μg/L). Furthermore, the posttraining serum free Hb levels were significantly elevated (P=.011), and the serum Hp levels were significantly decreased (P=.005), with no significant differences recorded between the FPs and GKs. However, the overall distance covered and the movement speed were significantly greater in the FPs. The increases in free Hb and decreases in Hp levels provide evidence that a typical team-sport training session may result in significant hemolysis. This hemolysis may primarily be a result of running-based movements in FPs and/or the plyometric movements in GKs, such as diving and tackling.