Changes in Inflammatory Response and Performance to Field Tests Induced by a Concomitant Training Block in Elite Handball Players in Benin

The effects of different training methods on immune function in African elite handball players have been little evaluated. The aim of this study was to determine the effects of a six-week concomitant training (CT) block on parameters associated with the inflammatory response and performance on field tests in elite handball players in Benin. This was a controlled interventional study, undertaken with 18 international handball players (21.4 ± 3.0 years), randomized into two groups: interventional (IG) and control (CG). Players of the intervention group (IG) participated in a concomitant training block (CT) and those who served as controls (CG), followed the usual content of their training sessions (UC). Interleukins Il-6 and Il-10, tumor necrosis factor (TNF-α), as well as performance in five field tests, were determined at the be-ginning and end of the six-week of training. Changes in inflammatory response parameters recorded in IG were similar to those in CG (P > 0.05). Improvements recorded were greater in the IG group than


Introduction
In team sports, training aims to improve the performance capacity of athletes in competition. The achievement of performance requires a good interaction between training loads and recovery times, which induces the establishment of overcompensation favorable to progress (Mujika, Halson, Burke, Balagué, & Farrow, 2018). On the other hand, failure to allow adequate recovery time can lead to undesirable situations such as overtraining. Overtraining is associated with adverse effects on immunological and biochemical parameters, leading to a decrease in performance capacity and an increased risk of physical damage, including damage to muscle function (Cadegiani, da Silva, Abrao, & Kater, 2020).
Elite players often use means such as balneotherapy, physiotherapy, massage and dietary techniques to speed up recovery (Walsh, 2019;Reilly, Drust, & Clarke, 2008). Although it is often possible for them to use these techniques, training for elite handball players also includes sessions in which physical preparation sequences are integrated and especially those aimed at developing the capacity for quick recovery (Jidovtseff, 2013).
Indeed, the training time and number of sessions generally do not exceed respectively 8 hours and four per week. Strategies to accelerate recovery between training sessions, during a training camp for example, such as massages, cold baths and physiotherapy, are little accessible. It is therefore necessary to consider the use of training methods, which, while inducing the development of physical abilities, promote that of the rapid recovery capacity, because the work intensities are often close to those recorded during the matches.
These training methods promote a good stimulation of the physiological adaptation mechanisms of the players, allowing the rapid recovery of the body and more particularly that of muscle function, as well as the parameters associated with the inflammatory response (Khan, Moiz, Raza, Verma, Shareef, Anwer, & Alghadir, 2016). Indeed, when the muscles are accustomed to a high level of effort during training sessions, the risk of injury to the muscle fibers during matches and the installation of the inflammatory process during recovery is reduced (Khan et al., 2016). One training method that, has emerged as suitable for the simultaneous development of rapid recovery of immune function, muscular capacities such as explosive strength of the pelvic and thoracic limbs, repeated sprints, running speed and maximum aerobic speed, is concomitant training  (Methenitis, 2018;Sellami, Gasmi, Denham, Hayes, Stratton, Padulo, & Bragazzi, 2018;Salamat, Azarbayjani, Yusof, & Dehghan, 2016;Marin, Bolin, Campoio, Guerra, & Otton, 2013;Buchheit, 2008). This method is generally, based on high intensity exercises, aiming consecutively at the development of maximal aerobic speed (MAS) and muscular strength in the same session (Methenitis, 2018). It also favors the development of the capacity for repeated sprints (Methenitis, 2018;Buchheit, 2008), physical fitness and athletic performance in children and particularly adolescents (Hebisz, Hebisz, Borkowski, & Zatoń, 2019;Gäbler, Prieske, Hortobágyi, & Granacher, 2018) and the improvement of the fatigue index, which is fundamental for the quick recovery of the body (Buchheit, 2008). Concomitant training resulted in reduced muscle damage in cyclists (Hebisz et al., 2019) and LDL with multiple cardiometabolic benefits in adults (Da Silva, Baptista, Neves, De França, Loureiro, Lira, Caperuto, Veríssimo, & Martins, 2020).
Data on the effect of a concomitant training (CT) program on field-test performance and parameters associated with the inflammatory response of handball players in sub-Saharan Africa are rather scarce. Even in Europe, the few studies that have been conducted, using methods other than the one in this research, have explored only immune function (Sellami et al., 2018;Marin et al., 2013).
However, research on the effect of concomitant training in healthy Iranian students reported a decrease in pro-inflammatory cytokines, including IL-6 and TNF-α after 8 weeks (Salamat et al., 2016). Determining the effects of a concomitant training program on inflammatory responses and performance in field tests is also important if, maintaining good player health is a priority. This, in turn, will promote optimal performance. The aim of this study is therefore to determine the effects of a six-week concomitant training block on both parameters associated with the inflammatory response and performance in field tests in elite handball players in Benin.

Participants
The study was undertaken with 18 international handball players, 9 juniors and 9 seniors. To be included in the study sample, the following inclusion criteria had to be met: playing in the Republic of Benin Division 1 Championship and be a member of this nation under-21 (U21) or senior team of the current year and having played in international competition during the past season; giving their informed free consent form to participate in the study. The 18 players were randomly divided into two equal groups, i.e. an interventional group (IG) and a control group (CG). The IG group participated in some concomitant training (CT) sessions and the CG followed the usual content of their training sessions (UC). Players who were injured and/or ill were not included in the sample.
Participants who were retained but subsequently missed more than 3 training sessions should be excluded.

Blood Tests
Each player had their last meal more than 3 hours before the start of their blood samples and each time five milliliters (5 mL) of blood was taken from each player by venipuncture from the left elbow into dry tubes. Blood in the dry tubes was centrifuged in the laboratory at 3000 tr/min for 10 min within one hour of collection to recover the serums, which were stored at −80˚C and then used for the determination of IL-6, IL-10 and TNF-α cytokines. Ready-Set-to-Go ELISA kits (Invitrogen ® ) with microplates were used, to determine the serum concentrations of each cytokine according to the protocol proposed by the fabricant.
The "Sandwich" ELISA technique has been used, for the more sensitive cytokines assay. The detection limits of the cytokines were 2 pg/mL for IL-6 and IL-10 and 4 pg/mL for TNF-α.
A Thermo Scientific TM WellwashTM versa microplate washer was used for plates washing after each step. At the end of the reaction, the optical densities of the product obtained for each cytokine were measured at 450 nm according to the supplier's recommendations, using a Tecan plate reader Infinite (200Pro ® ) photometer and Tecan ® i-control software version 1.12.4.0. Concentration curves obtained from the standards provided by the manufacturer (IL-6 from 2 to 200 pg/mL, IL-10 from 2 to 300 pg/mL and TNF-α from 4 to 500 pg/mL) were used to determine the concentration of each cytokine using Excel ® software (Excel, An OptoJump Next device (Microgate, Italy) was used to perform the counter-movement jump (CMJ) test. The height (in cm) of the best trial out of the five performed was used. The strength of the thoracic limbs was assessed with 3 kg medicine balls, according to the protocol proposed in the literature (Palao & Valdes, 2013). Of the three tests in this protocol, the eccentric-contraction throw (ECT) which appears, to be the closest to the specific actions of handball, was chosen. It consisted of performing the throw in three attempts, each time with both arms moving from the front to the back. During the throws, the players were not allowed to change their starting position. A DVD/CD tape player and a pre-recorded USB key of the 30 -15 IFT test (Buchheit, 2005)  and Trec representing rectal temperature before and after the test respectively, HR 0 and HR t , heart rate before and at the end of the training session (Moran, Shitzer, & Pandolf, 1998). The PSI rating scale proposed by the authors was used to determine the level of heat stress experienced by the athletes during the training sessions. At the end of each training session, the players individually expressed their perception of the effort made on the Borg scale (Borg, 1970 The training sessions focused on improving technical and tactical skills in attack and defense. The usual training session consisted of three parts. a) The first 30 min session consisted of sprints sequences over 5 m, 10 m and 30 m, to maintain the ability of reaction, start and race speeds. These sequences were performed in 3 series of 5 to 8 repetitions each. The passive recovery time between two repetitions of sprints was 30 s to 60 s and the rest between two series was 2 to 3 min.
b) The second part, lasting 55 minutes and organized after 5 minutes of stretching, was reserved for the development of technical and tactical attacking skills over three weeks, and then defense over the following three weeks. In attack, the players first carried out sequences to improve the quality of mid-distance shots (suspension shot from 9 m, change of direction with a series of 6 shots on each side, i.e. at the right and left fullback positions). Then they performed a series of 6 passes at the fullback position and give-and-go with shooting, in 2-on-0 and 2-on-1 situations. In defense, the players first executed 1-on-1 sequences at the back posts, carried out in a series of 6 series per back post and per defender.
Then they played man-to-man defense over the whole field, half the field, and then a third of the field, in a 3-on-3, 4-on-4, 5-on-5 game situations respectively for the sessions: • N˚ 1 to 3 (6 series of 1-minute, with 3 minutes of active rest between series); • No. 4 to 6 (4 series of 1 minute 30 s, with 4 minutes 30 s of active rest between series); • N˚ 7 to 9 (3 series of 2-minute, with 5 minutes of active rest between series).
c) The third part, which lasted 15 minutes, was reserved the implementation of the day's learnings on full court.

Concomitant Training Block (CT)
The aim was to develop physical and technical skills in defense and then in attack. The sessions were composed of three parts: a) The first 30 minutes, i.e. 25% of the total training time, was reserved for b) The second part had the same content as the regular training program. It lasted 55 minutes (45% of the total time) and included after 5 minutes of stretching, sequences to improve the technico-tactical abilities of attack, then defense.
c) The third part, which lasting 15 minutes (12.5% of the total time), was reserved for the global implementation of the day's learnings in full court game.

Statistical Analysis
The data were processed with the Satistica software (Stat Soft Inc., version 12).
Descriptive results are presented as mean (m) ± standard deviation (s) for the characteristics of the handball players studied and mean (m) ± Standard Error of the Mean (SEM) for the variables studied. The normality of the distribution of variables was checked using the Kolmogorov-Smirnov test. As the distribution was non-normal, the Wilcoxon rank test was used to make the comparisons within the groups, and then the U of Mann-Whitney test was used to compare the IG and CG groups. The significance level of the statistical tests was set at p < 0.05.

Results
Regardless of the characteristic considered (Table 1), the differences observed between the two groups of handball players studied were non-significant (P > 0.05).
In the IG group, the IL-6 and TNF-α means decreased by 65.3% (P = 0.007) and 47.9% (P = 0.007) respectively at the end of the CT block ( Table 2). The same was true for the CG group at the end of the UC program for IL-6 (44.9%; P = 0.007) and TNF-α (54.2%; P = 0.007). In contrast, IL-10 increased by 190.4% (P = 0.01) in IG and 162.9% (P = 0.01) in CG. Changes in IL-6, TNF-α and IL-10 recorded in GI did not show significant differences (P > 0.05) with those observed in CG.
production of pro-and anti-inflammatory cytokines in a similar way to that induced by the usual content of their training sessions, but improves performance in physical field tests to a greater extent. Elite handball players were chosen because of the high physical and psychological loads of training and competitions suspected of affecting the immune system if fatigue and stress are persistent. In effect, psychological stress associated with training and competition at the elite DOI: 10.4236/ape.2021.114040 498 Advances in Physical Education level may be an additive factor to the effects of intensive exercise on immune function, as well as lake of rest and good food intake (Gleeson, 2006;Nieman, 1997). The results obtained are valid only for the handball players included in the study sample since the non-random sample does not allow the generalization of the conclusions to all handball players in Benin. Players selected to undertake this study have a good level of practice, since the resting heart rate values recorded, lower than 60 bpm and those of 2 VO max  , between 50 and 60 mL/min/kg, correspond to the data reported in well-trained athletes (Kenney, Wilmore, & Costill, 2017;Sporis, Vuleta, Vuleta Jr, & Milanović, 2010).
At the end of the six weeks of training, the difference between the modifications recorded in the intervention group and those observed in the control group was not significant for any of the parameters associated with the inflammatory response. However, significant variations were recorded in each group considered separately. Thus, it appeared that both training contents had a positive (anti-inflammatory) effect on the organism of the handball players studied. In both groups, the means of IL-10, cytokine with the strongest anti-inflammatory effect of the selected ones, were increased, thus protecting the players against inflammation (Sellami et al., 2018). This positive effect of both training contents is reinforced by the decrease in IL-6. This cytokine is pro-inflammatory (Cantagrel, Degboé, Constantin, & Davignon, 2017) but also has anti-inflammatory effects, because it activates the production of classical anti-inflammatory cytokines such as the interleukin-1 antagonist (IL-1ra) and IL-10 (Pedersen & Febbraio, 2008).
The protective effect of these two contents was also enhanced by reducing the concentration of TNF-α, an exclusively pro-inflammatory cytokine (Cantagrel et al., 2017).
IL-6 therefore probably contributed to the elevation of IL-10 in both groups at the end of the six weeks of training. IL-10 in turn would have inhibited the production of IL-6 and TNF-α (Cantagrel et al., 2017). Thus, it is possible to deduce that the increase in IL-10 and subsequent decreases in IL-6 and TNF-α are related to the fact that the anti-inflammatory effects induced by the two training contents are higher than those associated with the pro-inflammatory process, over the six-week period. This anti-inflammatory mechanism is probably related to the adaptation of skeletal muscles to training, which is responsible for the increase in levels of expression of the sensitivity of the receptors of the skeletal muscles to pro-inflammatory cytokines (Pedersen & Febbraio, 2008). Training has therefore most likely made the muscles more resistant to the inflammatory process, as evidenced by the decrease in these two cytokines IL-6 and TNF-α. In a study that investigated the effect of concomitant training on pro-inflammatory cytokines, a decrease in IL-6 and TNF-α was also reported after eight weeks (Salamat et al., 2016). The increase in IL-10, as well as the decreases in IL-6 and TNF-α levels in both groups in the present study can therefore be considered positive for the immune system. It was also found that in the handball players studied, the concomitant training did not stress the body more than the usual  (Methenitis, 2018).
The plyometric exercises practiced by the players in the intervention group certainly caused the improvements in performance recorded in counter-movement jump and then in eccentric-contraction throwing. These are indeed flexion-extension exercises, commonly called push-ups, for the thoracic limbs, and bench and multi-jump exercises for the pelvic limbs. All of these exercises involve contractions that place significant demands on the elastic elements of the muscles (Castagna & Castellini, 2013). The increase in performance in eccentric-contraction throwing and counter-movement jump in the intervention group may also be partly associated with the effects of the joint work sequences, devoted to learning the techniques of shooting, counter-shooting and one-on-one attack.
In each group, similar improvements in the 30 m sprint time and in the mean time of the six sprints in the repeated sprint capacity test were recorded. These improvements in each group can be attributed to the combined effects of sprints aimed at developing 2 VO max  in players assigned to the concomitant training and the sprints at maintaining running speed in the control group. It has been reported that, sprint repetition training improves the best single sprint time (Mohr, Krustrup, Nielsen, Nybo, Rasmussen, Juel, & Bangsbo, 2007), as well as the mean time over several consecutive sprints more than interval training (Buchheit, Mendez-Villanueva, Quod, Quesnel, & Ahmaidi, 2010). Other authors, however, believe that intermittent training is better than the sprint repetition method because it improves not only running speed but also the fatigue index (Buchheit, 2008).
In this study, concomitant training showed its potential to improve maximal aerobic speed in the short term, followed by explosive strength of the thoracic and pelvic limbs. It didn't, therefore, further improve the starting and running speed capabilities of the handball players studied. Under this study conditions, in relation to immune function, the handball players studied can use both training contents since they did not negatively affect the parameters associated with the inflammatory response. However, if they wish to improve physical capabilities, concomitant training is preferable to develop 2 VO max  and explosive strength capabilities. Therefore, they will need to use other methods such as combined training to develop the starting and running speed abilities, which are considered to be, determinants of handball performance (Dawson, 2012).

Conclusion
The objective of this study was to determine the effects of a six-week block of concomitant training on parameters associated with the inflammatory response and performance in field tests in elite handball players in Benin. The results confirm the research hypothesis that concomitant training induces pro-and antiinflammatory cytokine production in Beninese elite handball players over six weeks in a similar way to that induced by the usual content of their training sessions, but further improves performance in physical field tests. However, this improvement in performance was limited to tests of explosive strength capacity and maximal aerobic power. These results suggest that coaches can use this method to develop these physical abilities in their players without affecting their immune function. However, a more effective method of improving sprinting and repeated sprinting skills in this category of handball players will need to be sought.