Imersão em água fria não acelerou a recuperação após uma partida de futsal

INTRODUCCION: la inmersion en agua fria (IAF) es una estrategia de recuperacion popular, sin embargo, la evidencia de la efectividad de este metodo en el ambito deportivo es limitada.OBJETIVO: investigar el efecto de la IAF en el dolor muscular y en el rendimiento anaerobico despues de un partido de Futsal.METODOS: diez jugadores realizaron dos partidos simulados seguido de dos condiciones aleatorias de recuperacion (IAF o descanso pasivo - C) separado por siete dias. Durante las intervenciones de recuperacion, los jugadores se sentaron en una posicion comoda (C) o se sumergieron en una piscina con agua fria (condicion de la IAF; 15±1°C) durante 12 minutos. La evaluacion del dolor muscular, la prueba de salto contra movimiento (SCM), prueba de saltos repetidos (PSR) y la prueba de sprints repetidos (PSPR) se realizaron antes del partido (PRE), inmediatamente despues de la intervencion de recuperacion (P1) y 24 horas despues de la intervencion de recuperacion (P2).RESULTADOS: la sensacion de dolor muscular aumento despues de partido de Futsal para ambas intervenciones (IAF y C) (P1 y P2; p 0,05). El rendimiento anaerobico disminuyo (SCM, PSR y PSPR) inmediatamente despues de la intervencion de IAF en comparacion con C (P1, p 0,05).CONCLUSION: el IAF no ha mejorado la recuperacion relacionada con el dolor muscular y rendimiento anaerobico de los jugadores de Futsal.


INTRODUCTION
There is a growing interest on interventions to accelerate the recovery process so athletes might perform successive training sessions or competitive matches without a significant decrement of performance. Recently, cold-water immersion (CWI) has emerged as one of the most popular interventions to accelerate recovery after exercise 1,2 . However, there is limited data regarding the effectiveness of this intervention in sport-specific settings.
Research on CWI interventions to accelerate recovery show conflicting results since some studies suggest positive outcomes 3-5 while others report non-significant effects [6][7][8] . Despite this controversy, athletes has been used CWI to promote a faster recovery, to diminish muscle soreness, and to hasten a return to optimal performance 1,2,9 . As a specific example, CWI has been largely utilized by Brazilian Futsal players between successive training sessions and competitive matches. However, there is insufficient evidence to support the use of this strategy following Futsal training sessions and competitive matches.
Futsal is a high intensity intermittent sport that relies on mixed contribution of anaerobic and aerobic energy systems 10 . Barbero-Alvarez et al. 11 and Castagna et al. 10 have shown that the Futsal match demands are higher than soccer and other intermittent team sports. Futsal physical demands indicate that the competitive match might induce severe fatigue, and may require efficient recovery interventions.
To date, no previous study has been conducted to verify the impact of CWI on muscle soreness and anaerobic performance of top-level Futsal players following a match. Therefore, the purpose of the present study was to investigate the effect of CWI on muscle soreness and anaerobic performance after a simulated match. The authors hypothesized that CWI would attenuate muscle soreness and minimize performance decrement thus accelerating recovery.

METHODS
The present study was conducted at the beginning of the competitive season (State Championship). The Futsal team involved in this study finished the season in the second position. All players were familiar with testing procedures used in the investigation. Players performed two highly competitive simulated matches (four quarters of 10 min with 5-min recovery period) separated by seven days in an ecological setting, using procedures previously described 10,12 . It is important to highlight that verbal encouragement was provided by the coaches during both matches. Each match was followed by one of two recovery interventions, a passive recovery (Control -C) or a CWI intervention. The respective interventions were randomized and performed at the same time of day to avoid diurnal variation. Thus, the order of recovery intervention (CWI and C) was individually counterbalanced. The recovery interval from the last bout of exercise was more than 48 h. To assess match intensity, a rating of perceived exertion (RPE) was recorded for all players after each match using Borg's CR-10 scale 13 . The players were familiarized with this procedure during prior training sessions.
To determine the effect of CWI on muscle soreness and anaerobic performance, the assessments were conducted prior to the match (Pre), immediately after the recovery intervention (P1) and 24h after the recovery intervention (P2). During the recovery intervention, the players remained seated in a comfortable position (control condition; C) or were seated (immersed) in a plunge pool set at 15 ± 1 o C for 12 min (CWI condition). The experimental design is illustrated by figure 1.
Ten male professional Futsal players (age: 24 ± 3 years, height: 174 ± 5 cm, body mass: 73 ± 9 kg) volunteered to participate in this study. The athletes belonged to a team from the Professional National Brazilian Futsal League. Players trained five days per week and played one match per week. All the participants were volunteers and took part in the present study after giving their signed consent. All procedures received Institution Ethics Committee approval.
Muscle soreness was assessed using a visual analog scale (VAS) of 100 mm line with "no pain" on one side and "extremely sore" on the other 14,15 . The athletes recorded the magnitude of muscle soreness during the stretching of biceps femuralis muscle 14 .
The performance tests were conducted at the three time points: before the match (Pre), 10 min after the recovery intervention (P1), and 24h after the recovery intervention (P2). All players were assessed in the same order in all time points. The counter movement jump (CMJ) was performed according to subject's own preferred style as suggested by Bobbert et al. 16 . Subjects performed three CMJ trials on a jump mat (Jump System Pro ® -Cefise ® , Brazil), and the best result was recorded. The repeated jump ability test (RJA) and the repeated sprint running test (rRST) were performed in this sequence. The RJA test was conducted according previous procedure 17 . In the RJA test, the players had just 1 attempt on a continuous countermovement rebound jump for 15 seconds without any recovery between jumps on a jump mat (Jump System Pro ® -Cefise ® , Brazil) 17 . The average of height of all jumps was considered for analysis. The players were instructed to jump as high as possible with their hands on their hips and to keep foot contact on the mat as short as possible. The RJA showed an ICC of 0.79. The rRST consisted of five 30-m sprints, each separated by a 25-s period of active recovery (jogging) 18 . Infrared light sensors with a precision of 0.01 s recorded the sprint times (Cefise ® , Brazil). The mean sprint time was considered for analysis. The rRST showed an intraclass correlation coefficient (ICC) of 0.93.

Statistical Analyses
The distribution of the data was analyzed by the Shapiro-Wilk test. The Mauchly's Test of Sphericity was performed to test the null hypothesis that the error covariance matrix of the orthonormalized-transformed dependent variables was proportional to an identity matrix. Two-way ANOVA with repeated measures was used to compare the two recovery procedures on three time points (Pre, P1 and P2). Tukey HSD post hoc test was utilized when necessary. In the case of violation of the assumption of sphericity, the significance was established by utilizing the Greenhouse-Geisser correction.

RESULTS
A similar session rating of perceived exertion (RPE) was observed for the two simulated matches (1 st match: 6.8 ± 1.4, "hard" to "very hard"; 2 nd match: 6.7 ± 1.2, "hard" to "very hard"). Figure 2 shows the muscle soreness of Futsal players. A significant increase in muscle soreness after the Futsal match was observed for both interventions during all time points (P1 and P2); however, no significant difference (p>0.05) was detected between CWI and C interventions. The results of the anaerobic performance tests (CMJ, RJA and rRST) are shown in figures 3, 4 and 5. There was a significant decrease in anaerobic performance (CMJ, RJA and rRST) immediately following  the CWI intervention when compared to C intervention (P1, p<0.05). No significant difference in anaerobic performance was detected between CWI and C at P2 (p>0.05).  Pre=pre-match; P1=immediately after the recovery intervention (control or CWI); P2 = 24h after the recovery intervention; C=control; CWI=cold-water immersion; a =Different from pre-match for both groups (p < 0.05); b =Different from control group (p < 0.05).

DISCUSSION
The present study aimed to compare the effect of two recovery methods (passive and CWI) performed after a simulated Futsal match. This is the first study that analyzed the effect of CWI on muscle soreness and anaerobic performance after a Futsal match in top-level Brazilian professional players. The major findings of the present study were as follows: 1) CWI did not attenuate the magnitude of muscle soreness induced by a simulated Futsal match, 2) A significant decrease in the post-match anaerobic performance was observed immediately after the CWI intervention and 3) no difference in anaerobic performance was observed between both interventions after 24h.
The mean RPE score for both matches was similar (~7.0), indicating a perceived exertion between "hard" and "very hard". Tessitore et al. 19 showed that young Futsal players perceived the mean intensity from four friendly matches as "somewhat hard" using the Borg´s 6-20 Scale. These findings highlight that players attained a high-intensity effort during both matches. Previous studies confirm the high physiological demands of Futsal matches 10,11,20 .
Nowadays many athletes and coaches habitually use CWI after intense training sessions or competitive matches expecting that this intervention will accelerate recovery 1,2 . To date, only one study has investigated recovery procedures in Futsal players 19 , but the sample were composed by young players, members of college Futsal teams. Furthermore, Tessitore et al. 19 did not evaluate the impact of CWI as a recovery strategy.
In the present study, CWI intervention did not decrease the magnitude of muscle soreness after the match (24h post-intervention) when compared to the passive recovery (C). In agreement with the findings of the present study, Jakeman et al. 21 also showed that a single bout of CWI (10 min at 10 o C) following a damaging exercise (10 sets of 10 counter--movement jumps) has no beneficial effect on perceived muscle soreness during recovery (1,24,48,72, and 96h after the exercise). Yanagisawa et al. 22  However, other investigations showed that CWI attenuates muscle soreness 4,5 . The recent meta-analyses conducted by Leeder et al. 1 and Bleakley et al. 2 showed that CWI is effective to alleviating muscle sore-ness after damaging exercise between 24h up to 96 h of its application. One mechanism that has been proposed to explain the attenuation of muscle soreness is that CWI causes reduction in muscle blood flow and tissue temperature, lowering the inflammation induced by high-intensity damaging exercise. This intentional reduction of inflammation might be related to attenuation of DOMS 1 .
Regarding to the effect of CWI on physical performance the results are also diverse and inconsistent 1,2 . The results of the present study indicated that CWI may impact negatively in anaerobic performance assessed immediately after the intervention. A significant decrease in CMJ, RJA and rRST performance was observed immediately after the CWI. In line with these results, Crowe et al. 8 observed a decrease in anaerobic performance (30-s "all out" maximal cycling test) after CWI (15 min at 13-14 o C). In this study, peak power, total work and post-exercise blood lactate were significantly reduced following CWI compared to the first exercise test and the control condition 8 . Buchheit et al. 24 did not show a significant difference in mean power output and completion time during 1-km cycling time trials between the CWI (5 min at 14 o C) and passive recovery in male cyclists, despite the improvement of perceived rating of recovery after the CWI. Likewise, Jakeman et al. 21 showed that after a damaging exercise, the CWI did not show a positive effect from recovery of maximal voluntary contraction of the quadriceps up to 96h after its application when compared to the passive recovery.
In the present study, the decrease in anaerobic performance immediately after the CWI could be explained by the lower muscle temperature. The possible mechanisms involved in the performance deterioration include decreased stiffness of muscle and joints, increased transmission rate of nerve impulses, altered force-velocity relationship and increased glycogenolysis, glycolysis, and high-energy phosphate degradation 25 . Therefore, a lower muscle temperature immediately after the CWI might have impaired muscle contractile ability and exercise performance. García-Manso et al. 26 showed that CWI may modify skeletal muscle physiology of professional soccer players, increasing stiffness and decreasing muscle contraction velocity. On the other hand, the benefits of warm-up on the short-term neuro-muscular performance appear to be largely, although not entirely, attributable to the increase in muscle temperature 25 .
More recently, Stanley et al. 27 investigated the effects of CWI on both central (i.e., cardiac output) and peripheral (i.e., muscle oxygenation) facilitators of O 2 delivery to exercising muscle. In addition, these researchers also assessed the influence of CWI on the anaerobic contribution during subsequent high-intensity interval training (HIIT) 27 . Interestingly, they showed that using CWI prior to a subsequent HIIT led to increased cardiac parasympathetic activity, slowed VO 2 on-kinetics and reduced muscle O 2 utilization, probably due to the reduced muscle blood flow 27 . In addition, CWI increased anaerobic contribution during HIIT 27 . These central and peripheral responses seem to persist up to 45 min. From the practical point of view, the authors suggest that athletes should be advised to not use CWI if high-intensity events are separated by 45 min or less.

CONCLUSION
In summary, the results of the current study indicate that a single bout of CWI after a simulated Futsal match had no beneficial effect on perceived muscle soreness and anaerobic performance during a short-term recovery period. However, additional studies are necessary to analyze the effect of different CWI protocols on recovery of Futsal players during tournaments with subsequent matches in a short period of time.