It has been postulated that recovery is an important factor in athletic life and that optimal recovery may prevent underperformance (14). Currently, players in elite sport cycle through habitual activity across each week of a season (6). This cycle of habitual activity includes training, game time, and recovery over each competitive week (18). In addition, the relative short turn around between games and training may lead players to accumulate fatigue as the season progresses (18).
A number of recovery modalities, including cryotherapy and contrast baths, have been adopted by sporting teams to assist player recovery. A comprehensive search through sports science and sports medicine databases found limited papers into recovery modalities and their outcomes. Additionally, the majority have used untrained subjects, with only a small number evaluating the benefits of recovery strategies with well-trained athletes.
Published papers on recovery offer conflicting results in the benefit of hydrotherapy for recovery. No significant differences were identified across 4 recovery protocols with elite junior soccer players in 10-m sprints or countermovement jumps (21). Multiple recovery protocols were used in testing Australian Rules footballers (7); dependent variables were not significantly enhanced by performing immediate postgame recovery protocols. In contrast, cold water immersion was found to promote restoration of physical performance measures over a 3-day basketball tournament (15).
It was reported that consequences of performance decrements immediately after cold whirlpool immersion needed to be considered before returning athletes to activity posttreatment (16). Additionally, ice water immersion was shown to be ineffectual in minimizing markers of delayed onset of muscle soreness (DOMS) with untrained men (20). However, ice baths were identified to delay the perception of fatigue and leg soreness in junior elite soccer players over a week of tournament play (19), although no clear beneficial effect on physical performance was identified. However, 10 minutes of ice bath identified trends in recovery through effect sizes from simulated team sport (13).
Cold water immersion was found to be effective in maintaining subsequent performances in high-intensity cycling (24) and across 5 days of cycling (23). In contrast, no effect on isokinetic strength or 1-km time trials in cycling was identified after cold water immersion (17).
Research into recovery for highly or well-trained athletes identified that return in squat-jump peak power in highly trained athletes occurred more quickly with contrast therapy than with passive recovery (22). In contrast, contrast therapy was found to offer no enhancement in recovery from simulated team sport. In addition, neither contrast baths nor compression garments showed any benefit to recovery from exercise induced muscle damage (9).
Reported mechanisms of hydrotherapy enhancing recovery include reduction in inflammation and diminishing the stretch-reflex response to elongation (5). Hydrotherapy reduces blood flow through vasoconstriction of the arterioles and venules (1). In addition, hydrotherapy has been shown to reduce tissue temperature lowering the rate of chemical reactions (12). The reduction in the rate of chemical reactions leads to a reduction in the demand for adenosine triphosphate (ATP), reducing the requirement for oxygen and reducing the adverse effects of hypoxia (12). Hydrotherapy has also been shown to aide in metabolic waste product removal via increase in circulation through vasodilatation and vasoconstriction assisting the venous pump (10).
The current research problem with team sports which consist of high levels of collisions or impacts such as rugby union, is will different recovery strategies including cryotherapy have a positive influence on anaerobic recovery, as measured by performance in anaerobic tasks dependent on anaerobic glycolysis? In this research, it was hypothesized, based on the review of the literature, that contrast baths would be superior to ice baths and passive modalities in enhancing anaerobic recovery, as measured by a phosphagen decrement test and 300-m test.
Experimental Approach to the Problem
In the present study, a random control trial research design was used. Subjects were required to undertake take four competition games of rugby union across four weeks. Subjects were also required to undertake two training sessions per week. After each game and each training session subjects underwent one of three recovery modalities (ice baths, contrast baths or passive recovery). Pre-test were conducted in the week preceeding the first game. Post-tests were conducted the week after the fourth competition game. All testing was conducted at the teams scheduled training sessions.
Subjects were members of an under 20 rugby union team (colts) competing in the Sydney Premier Rugby Competition (see Table 1). Following the Australian Catholic University's ethics committee approval, and in accordance with guidelines for the use of human subjects in research, a Premier Rugby Union club was approached to participate in a random control trial (RCT). Male players from the U/20 competition (colts) volunteered to participate in the RCT. Before commencing, players were given an information letter explaining the study and an opportunity to ask questions. Players volunteering gave written consent; players under the age of 18 provided a signed consent form from a parent or guardian.
Having previously identified the most common recovery methods in rugby (11), ice baths and contrast baths were selected for this study as the independent variable. A control group was established for comparison purposes. The participants in the control group were instructed to perform passive recovery, which involved passive rest following training sessions.
The RCT was conducted during weeks 5-9 inclusive of the 2008 rugby union competition. Players suffering an injury or illness during the period or were part of the National Training Squad were excluded from the study. Players with known allergies to cold or displayed symptoms such as rashes were withdrawn from participation in the study.
A convenient sample of Colt Rugby players (n = 26) met the inclusion criteria to participate in the study. Training was conducted as a squad including warm-up (20 minutes), fitness training (30 minutes), skill session (45 minutes), and opposed team run (20 minutes). Training loads were kept constant across all participants during the study, in line with the teams' periodized training schedule. Training loads and intensities had been previously established for each drill with data trackers (GPSpi 10, Canberra, Australia).
The participants were randomly assigned to 1 of 3 groups: ice baths (11), which involved immersion in cold water for 5 minutes, above the waistline, with a temperature range of between 10 and 12° C; contrast baths (11), which involved alternating from cold water at temperature range between 10 and 12° C and warm water at a temperature range of between 38 and 40° C for 60 seconds in each cycle, through 7 cycles. Finally, those in the control group were to follow a passive recovery strategy.
It has been reported that energy contributions in intermittent team games are primarily anaerobic (8). There is also a requirement for high anaerobic capacity during sustained and repeated intense efforts in rugby union (8). Therefore, tests to be used included a phosphate decrement test, which involved 7 all out sprints for 7 seconds with 21 seconds recovery and a 300-m sprint test.
Testing was carried out after the squads' standardized warm-up, which included 2 Honan drills for 15 minutes at training. Baseline phosphate decrement was conducted on Monday of week 1 of the study; the baseline 300-m test was conducted on Wednesday of week 1 of the study. Ice baths and contrast bath treatments were applied after all training session and each competition game.
The phosphate decrement test was performed on a grass covered rugby oval with participants performing the test in 3 random groups. Standard training cones were placed across the field every 2 m for 50 m, to measure distance covered in each sprint. The 7 second time for sprints and 21-second time for recovery was monitored by the researcher, using a standard handheld stop watch. Start and end sprints were signaled by the researcher blowing a referee's whistle.
Each group lined up alongside the first cone, at the sound of a referees' whistle; each participant would sprint for 7 seconds, at 7 seconds the referees whistle would be blown again. Participants would then line up alongside the last cone at the opposite end, after 21 seconds the referee's whistle would be blown again. The cycle was repeated until the group had completed 7 sprints. Each participant was instructed to use maximal effort.
Each participant was assigned a spotter to identify which cone they had last passed at the sounding of the referees' whistle. Each cone had previously been identified with an identifying value. After the blowing of the whistle, the spotter would identify the last cone their assigned participant had passed, the identified cone would then be recorded next to the participant's name for statistical analysis.
A pilot study to test the reliability of the phosphate decrement test, which included 7 participants from the same pool of subjects, with 4 markers assigned to each, identified a coefficient of variation from between 3.2 and 4.9% across the 7 runs between subjects and across markers. A reliability statistic of Cronbach's Alpha 0.926 was also reported.
The 300-m time trial was conducted around the training oval, with the distance paced out with the use of a trundle wheel and agility posts placed every 20 m to mark the course. Participants performed the time trial in 3 random groups, running in an anticlockwise direction. Each participant was assigned an individual time keeper who recorded the time with a standard, handheld stop watch.
Subjective self-reports were also received from players. Reports included how rested they felt, how tight they felt, and whether they felt the treatment was beneficial. Retests were conducted on the fifth week of the study. The phosphate decrement test and the 300-m sprint test were conducted using the identical protocol as for baseline tests.
The statistical analyses were facilitated by SPSS version 15.0, which included between-group and within-group analyses. One-way analysis of variance (ANOVA) evaluated between groups for significant difference on the pretest scores to confirm equality of groups and group variances before posttest analyses. Initial differences at the pretest level based on participant scores were identified to adjust for any initial difference between groups analysis of covariance (ANCOVA) tests were conducted on the posttest scores as the dependent variable; the between group factor was the treatments and the pretest scores were defined as the covariate. A mixed ANOVA design was also applied to understand any changes in between group (treatment) and within group (pretest to posttest) simultaneously.
Effect size analyses (Cohen's d) were conducted to identify in detail outcomes based on treatment effects (23). Effect sizes were assessed in line with Batterhan and Hopkins (3) and included the following criteria <0.2 as trivial, 0.2-0.6 as small, 0.6-1.2 as moderate, 1.2-2.0 as large, and >2.0 as very large. It has been stated that parametric statistical tests based on statistical significant difference fail to address real-world significance of a practical treatment outcome (2,3), the concept in sport that is now referred to as performance significant outcomes. Additionally, inferences based on true effect sizes can be more important than statistical significance (2) because a nonsignificant result does not necessarily rule out a worthwhile effect (3).
Subject characteristics for age, height, and mass (mean plus ± SD) for the 3 treatment conditions are included in Table 1 (supplemental file). Mean training loads and heart rate intensities are included in graph 1 (supplemental file).
Analysis of covariance test between groups for mean base tests and mean retests did not identify a significant difference vs. treatment for mean scores for the phosphate decrement test or 300-m test. The 300-m test indicated that there was a change from the pretest to posttest stage for all groups combined and that there was no interaction effect. The statistical results are displayed in Table 2 (supplemental file).
The pretest to posttest scores for all treatment conditions are displayed in Table 3, which indicates some of the trends in treatment effects (supplemental file).
Effect size calculations within the confidence interval of 95% identified a medium to large effect size (d = 0.72) for 300-m tests for contrast baths. A less than small effect size was identified for ice baths (d = 0.17) in the 300-m test. Effect size calculations within the confidence interval of 95% identified a small effect size (d = 0.18) for phosphate decrement scores for contrast baths. A negative medium effect size was identified for ice baths (d = 0.62) for phosphate decrement scores.
Further effect size analysis to compare treatment against treatment identified a greater than large effect size (d = 0.99) of contrast against ice treatment in the phosphate decrement scores. A medium effect size (d = 0.53) for contrast against ice treatment in the 300-m test was also identified.
From subjective reports, 5 of 7 participants from the ice bath group reported feeling more tight 2 days after games than when previously adopting no recovery strategies. All 7 participants in the ice bath group had a negative feeling toward the baths. Participants from the contrast group reported having a more positive feeling after the treatment: a feeling of being more relaxed and finding it easier to rest and sleep, postgame and posttraining.
Statistical analysis of baseline testing indicated there was no difference between groups, allowing assumptions that groups had similar anaerobic glycolytic fitness levels across tests at the start of the RCT. It is important to emphasize that no significant treatment or interaction effects were identified with mixed ANOVA repeated-measures analysis or with ANCOVA.
Results from effect size calculations identified a trend toward the use of contrast baths in recovery from team sports, when anaerobic performance is measured. Relating effect sizes through percentile standings (4) may indicate important sporting performance outcomes.
In team sports with well-trained and elite athletes, during a long competitive season, maintaining competitive performance and fitness is critical to success. In an environment where coaches and athletes are looking for every advantage over opponents, percentile ranking may partially support the strategies that are in use.
Medium to large effect sizes in the 300-m test for contrast baths indicate participants undergoing contrast treatment had mean scores at approximately the 76th percentile of mean scores for the control group. The trivial effect size in the 300-m test between ice bath and control group indicates little difference in outcomes between ice treatment and passive recovery.
Evaluation of ice baths against both the contrast bath group and the control group brings into question the use of ice baths in recovery. Effect size comparisons between the 2 treatments groups may indicate contrast baths may be of more benefit when compared to ice baths. Medium effect size indicates the contrast bath group would be at the 69th percentile of the ice bath in the 300-m tests. A large effect occurred in the phosphate decrement score for contrast baths over ice baths, which had participants at the 82nd percentile of ice baths. The trend for the phosphate decrement score is displayed in Figure 1 (supplemental file).
A negative medium effect with ice baths compared with control group questions ice baths for recovery, when tests relying on the phosphagen and anaerobic glycolysis energy system are measured.
In team sport, recovery from both training and competition is essential for the maintenance of performance across the season (14). During competition, turnaround times between training and games can be short. Recovery strategies that are employed need to provide benefits in physiological recovery. Additionally, in professional sport, there is a greater demand on athletes' time; necessitating the requirement of any training and recovery protocol implemented to be a proven benefit to the athlete.
It may be argued that employing protocols without significant support may merely add to athletes' restricted time burdens without providing benefit. Evidence has already established the importance of athletes recovering mentally from sport and its demands (14). Coaching staff need to assess whether the differences between contrast baths and passive recovery will be of a sufficient benefit. If athletes are showing signs of mental fatigue, any physiological advantage supported by effect sizes may be negated by additional time burden presented by scheduled recovery sessions.
With long seasons in professional competitions, players may develop psychological stresses leading to poorer performances (14). Extending game days or training sessions with recovery treatments that do not provide a significant difference may add to mental stressors, further diminishing performance.
Although 5-minute ice baths appear to have a wide use in sport, results of this study would indicate that their use is not warranted. Results may indicate that ice baths, of 5 minutes, have a detrimental effect on players' performance recovering from competition and training. The detrimental effect may be found when players are required to perform short, intense activities that rely on anaerobic energy systems.
The reason supporting 5 minutes for ice baths is unclear, because published research on timeframes of 5 minute appears scarce. In addition, Arnheim and Prentice (1) state that 15 minutes of immersion is required for vasoconstriction to occur. It may be that 5 minutes is insufficient time to lower tissue temperature enough to deliver benefits associated with cryotherapy as mentioned previously.
Reported purposes of contrast baths are enhancing circulation via aiding venous return through vasoconstriction and vasodilatation. Mechanisms aiding recovery may be via circulatory responses, including removal of metabolic wastes, reduction in edema and aiding delivery of oxygen to muscles.
In the sport of rugby, trends toward contrast baths benefiting recovery have been identified. The continued use of 5-minute ice baths should be reconsidered based on the findings of this research because there may be a detrimental effect, in particular when high intermittent, repeat performance, commonly found in team field sports, is required. In addition, coaches and trainers need to consider the benefit of recovery protocols established and examine if physiological benefits achieved justify the additional time burden placed on players who may have limited free time away from sport and consequences toward mental fatigue.
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