A total of 111 individuals participated in the study, which was male dominated [n = 96, 86%; X2(1, N=111) = 59.11, p < 0.001]. Respondent age differed significantly from randomness with the greatest response frequency in the 31–35 (n = 28, 25%) and 36–40 (n = 24, 22%) age groups [X2(7, N=111) = 36.39, p < 0.001]. Frequency of response from Performance Support personnel (Medical Staff, S&C, Sport Science) (n = 72, 65%) differed significantly from athlete/player (n = 28, 25%), coach (n = 9, 8%) and research (n = 1, < 1%), indicating that respondents were more likely to be performance support personnel [X2(4, N=110) = 158.55, p < 0.001]. Respondents most frequently reported having spent 0–3 years (n = 25, 23%) and > 15 years (n = 22, 20%) in their current/similar role [X2(5, N=110) = 10.66, p = 0.059].
The majority of respondents declared their role within a sport was in soccer (association football) (n = 44, 41%), with other notable frequencies for rugby/American football (n = 9, 8%), triathlon (n = 9, 8%), combat sports (n = 6, 5%), and seven respondents declaring involvement in multiple sports (6.5%) [X2(20, N=107) = 339.10, p < 0.001] (Fig. 1a). Most participants reported being involved in national (n = 33, 30%) and international (n = 31, 28%) competition, suggesting that 58% of participants were involved in elite level sport. The frequency of response for participant level of competition differed significantly from randomness, participants were more likely to be involved in international (n = 31), national (n = 33) and club (n = 22) than university (n = 1), county (n = 4), academy (n = 3) or non-competitive (n = 15) sport [X2(7, N=110) = 92.62, p < 0.001] (Fig. 1b).
Current use/prescription of CWI (Q8–18)
Of the entire sample, significantly more participants (n = 94, 86%) had used or prescribed the use of CWI for post-exercise recovery at some point during their career [X2(1, N=109) = 57.28, p < 0.001]. Respondents were significantly more likely to use pool/spa (specialised CWI system) (n = 32, 34%), bath tubs (n = 27, 29%) and makeshift tubs (wheelie bin or similar) (n = 23, 24%) than inflatable systems (n = 8, 9%), “cryotherapy chambers”, “chest freezer filled with water”, “cold shower/ocean” or “none” (all n = 1, 1%) [X2(7, N=94) = 106.00, p < 0.001]. When asked if they attempt to control the temperature of the water used, only 15 (16%) replied ‘No’. Most attempted to control the water temperature with the addition of ice/cold water (without monitoring for a particular temperature) (n = 34, 36%), whilst others added ice/cold water whilst monitoring for a particular target temperature (n = 16, 17%). 29 respondents (31%) utilised a temperature-controlled system/pump [X2(3, N=94) = 11.45, p = 0.010].
A target temperature for CWI of 9–11 °C was the most popular (n = 30, 32%), significantly more popular than other temperature ranges [X2(9, N=93) = 106.89, p < 0.001] (Fig. 2a). The next most common response was “no target temperature” (n = 23, 25%), followed by 12–15 °C (n = 15, 16%) and < 5 °C (n = 13, 14%). Immersion depth was varied within the sample: 33% (n = 31) reported using “whole body (i.e. head out)” immersion, while 43% (n = 40) immersed waist deep only; 24% (n = 23) did not control for immersion depth [X2(2, N=94) = 4.62, p = 0.099] (Fig. 2c). A single-immersion protocol was favoured (n = 69, 75%) over a two immersion period separated by a short break (n = 18, 20%) or varied (n = 5, 5%) protocol [X2(2, N=92) = 74.63, p < 0.001], with the highest number of responses indicating a cumulative immersion time per CWI session of 2.5–5 min (n = 30, 32%); followed by 7.5–10 min (n = 22, 24%) and 5–7.5 min (n = 19, 20%) and 10–12.5 min (n = 10, 11%) (X2(6, N=93) = 50.84, p < 0.001) (Fig. 2b). The time at which CWI was first completed following competition/training tended to be 15–30 min (n = 42, 46%) or 0–15 min (n = 26, 28%) (X2(8, N=92) = 161.96, p < 0.001) (Fig. 2d). Other responses included 45–60 min (n = 9, 10%), 30–45 min (n = 8, 9%), 24 h or “it depends” (n = 2, 2% each) with 3 h, 1 h and “0–30 min” reporting one count each.
Perceptions of CWI (Q.19–26)
The majority of participants (n = 79, 85%) reported having a positive perception of CWI, with only 2 (2%) expressing a negative perception; 12 (13%) responded with “don’t know” regarding their perception of CWI [X2(2, N=93) = 113.10, p < 0.001] (Fig. 3a). Of the respondents who reported having a positive perception of CWI, 72 provided details as to why. Their responses varied in detail; however, some themes were apparent in the responses. The most common was that players/athletes felt “fresher/refreshed” following CWI. Another common theme was that of enhanced recovery with several respondents mentioning improved time to recovery, a heightened sense of recovery and reduced sensations of DOMS and inflammation. A less common theme within the responses was that of psychological effects of CWI, participants mentioned: “feel good factor”; “psychological benefit for majority of athletes”; “mind–body connection”. A final theme, presumably from coaches and performance support practitioners, was that of receiving positive feedback from players/athletes on CWI, e.g. “best feedback”, “players get immediately relieved from fatigue”, “based on players’ positive feedback and short recovery duration”, “positive feedback from players”, “most players ask for it”. The two participants who reported a negative perception of CWI gave the following justifications: “Benefits muscles, particularly quads and hamstrings but found tightens Achilles”; and “Research, experience”.
When asked “can CWI help in the prevention and treatment of injury?”, response frequency differed significantly from randomness [X2(4, N=92) = 11.15, p = 0.025] (Fig. 3b). The most frequent response was “helps with the prevention and treatment of injury” (n = 25, 27%). Other responses included “helps with the treatment but not prevention of injuries” (n = 22, 24%) and “don’t know” (n = 22, 24%) and “helps with the prevention but not treatment of injuries” (n = 7, 8%). Sixteen participants (17%) had the perception that CWI could not help with the prevention and/or treatment of injury.
The significant majority (n = 71, 78%) of participants thought that CWI enhanced recovery post-exercise, 14% (n = 13) said they “don’t know” and 8% (n = 7) reported that they found no enhanced recovery following CWI [X2(2, N=91) = 82.37, p < 0.001] (Fig. 3c). With regard to CWI being able to enhance performance following recovery, participants who responded “yes” (CWI does enhance performance following recovery) had the highest response rate (n = 33, 36%), followed by “decrease in performance immediately post-CWI but improved performance several hours later or on subsequent days” (n = 26, 28%). Nineteen respondents (21%) stated that they did not know whether CWI enhanced subsequent performance, with the remaining respondents stating they believed it “depends” (n = 1, 1%), it could temporarily (n = 5, 5%) or did not enhance subsequent performance (n = 8, 9%) [X2(5, N=92) = 52.52, p < 0.001]. Respondents were significantly more likely to believe that most athletes/players/coaches/practitioners were aware of CWI and its associated benefits (n = 49, 53%) [X2(3, N=92) = 36.44, p < 0.001] with others either disagreeing (n = 13, 14%) or remaining neutral (n = 30, 33%). Respondents reported first becoming aware of the benefits of CWI through “scientific literature” (n = 46, 50%) and “fellow athlete/coach/practitioner” (n = 40, 43%).
Knowledge of CWI associated benefits and mechanisms (Q.27–30)
When assessing respondents understanding of the benefits associated with CWI, Question 27 asked participants what the benefits of CWI included, providing the opportunity to select all answers that they felt applied. Several participants (n = 19) left this question blank. The remaining participants displayed varied perceptions on the benefits of CWI; the majority expressed the belief that CWI reduced inflammation (76%) reduced pain sensations (74%), and reduced sensations of DOMS (74%). Respondents also reported psychological benefits (68%) and enhanced recovery time/return to play (65%) (Table 1). Question 28 asked participants to identify the physiological mechanisms behind CWI and the benefits it provides. Multiple answers were permitted with frequencies of choices identified in Table 2. More than 50% of respondents selected constriction of blood vessels, alterations in blood flow, and reductions in core, skin and muscle temperature alongside alterations in inflammatory biomarkers, as a mechanisms of CWI action.
If CWI is applied following strength/speed/power training, 19 (21%) of respondents agree or strongly agree that CWI would enhance adaptations to the training stimulus, while 44 (47%) disagreed or strongly disagreed and 29 (32%) had a neutral opinion [X2(4, N=92) = 22.78, p < 0.001] (Fig. 4a). Conversely, when asked if CWI enhanced adaptation to the training stimulus following endurance/high intensity intermittent training, the results again differed significantly from randomness [X2(4, N=92) = 23.33, p < 0.001] (Fig. 4b), displaying the opposite trend: 50% (n = 46) strongly agreed or agreed, 26% (n = 24) disagreed or strongly disagreed, with 24% (n = 22) of participants reported not knowing.
When respondents were asked when they would recommend the use of CWI for recovery more opted for “in-season” (n = 48) over “pre-season” (n = 20) and “immediately post-competition” (n = 52) over “immediately post-training” (n = 31). Respondents also highlighted that they would recommend CWI be used “after some competitions” (n = 35) more than “after all competitions” (n = 15), suggesting a periodised and tailored use. When asked when they thought CWI should be avoided the most popular answers were “immediately prior to competition” (n = 22) and “pre-season” (n = 15).
Questions 33 and 34 asked participants “For whom is CWI suitable?” and then asked for explanation of their previous answer. Several themes were identified in the explanation’s respondents provided. Several stated that CWI was suitable for all athletes; some provided greater clarity with the addition of words to the effect of “dependent on training/competition schedule” or “under appropriate circumstances”. Others identified a need to carefully plan when to utilise CWI with strength/speed/power athletes “so as not to negatively impact adaptation to training”. Many participants felt that there were clear benefits of CWI on endurance performance, but more information was required on its appropriate use for strength/speed/power.
Reasons for not using CWI
A total of 15 respondents reported not using CWI. When asked what their preferred method of recovery was, the most popular response was “massage” (n = 5, 33%), followed by “hot-water therapy” (n = 3, 20%). After being asked for their reasons for not using CWI, 47% (n = 7) reported not having access to facilities as the main reason whilst 20% (n = 3) reported not knowing CWI could be utilised for recovery.
The likelihood of respondents using or advocating the use of CWI currently or at any point previously did not differ between roles [X2(4, N=109) = 1.58, p = 0.81]. For questions seeking to determine current uses of CWI, when opting to control for a certain temperature of CWI significant differences existed between participants in different roles [X2(12, N=93) = 29.36, p = 0.003], with the majority of performance support practitioners (n = 25, 40%) utilising a temperature-controlled system/pump, with athletes (n = 11, 50%) and coaches (n = 4, 57%) more likely to use the addition of ice and cold water without monitoring for a certain temperature. Performance support practitioners were most likely to desire a water temperature of 9–11 °C (n = 26, 43%), athletes/players were most likely to report having no target temperature (n = 11, 50%), whilst coaches were most likely to report a target temperature of < 5 °C (n = 3, 43%) or have no target temperature (n = 2, 29%) [X2(36, N=92) = 162.35, p = 0.004]. Total immersion time per CWI session differed significantly based on respondent role [X2(24, N=92) = 37.55, p = 0.039]. Performance support practitioners most frequently reported an ideal total immersion time of 7.5–10 min (N = 17, 27%), with 2.5–5 min (n = 15, 24%) and 5–7.5 min (n = 16, 26%) also popular choices. The most frequent immersion duration among athletes/players (n = 11, 50%) and coaches (n = 3, 50%) was shorter, at 2.5–5 min. No differences were noted between the different roles for depth of immersion, number of immersions used and time until immersion after exercise (p > 0.05).
When asked if CWI enhanced subsequent performance following recovery, response frequency differed significantly between respondent roles [X2(20, N=91) = 108.13, p < 0.001]. Performance support practitioners were most likely to respond “yes” (n = 22, 36%) or “decrease performance immediately post-CWI but increased performance several hours later or on subsequent days” (n = 21, 34%). Athletes/players most frequently responded “don’t know” (n = 8, 38%) or ‘Yes’ (n = 7, 33%), with coaches most frequently responding ‘yes’ (n = 3, 43%). No differences were noted between the different roles for perception of CWI for recovery, if it is useful for the prevention/treatment of injury, or if it enhances performance (p > 0.05).
Inter-sport and experience analysis
Participants from all sports were equally likely to use/advocate the use of CWI, with chi-square cross tabulation of sport and CWI advocation/use insignificant [X2(20, N=107) = 24.04, p = 0.241]. The most commonly used method of CWI [X2(140, N=92) = 245.91, p < 0.001], choice to control for temperature or not [X2(60, N=92) = 91.57, p = 0.005], and target temperature of CWI [X2(180, N=91) = 246.27, p = 0.001], differed significantly between sports.
Analysis by level of competition
A significant difference was identified between the level of competition a participant was involved in and their likelihood of using/advocating the use of CWI [X2(7, N=110) = 15.26, p = 0.033]. CWI use tended to be more frequent in elite level of competition (i.e. international 97%, national 88%, non-competitive 67%). The controlling of CWI temperature [X2(18, N=94) = 32.66, p = 0.018] and target immersion temperature [X2(54, N=93) = 80.75, p = 0.011] differed significantly between levels of competition. The most popular target temperature was 9–11 °C (international, national, academy level) or no target temperature (county, club, university and non-competitive), suggesting more elite level sports adopt greater control over their recovery practices. Responses to the question “do you find CWI enhances performance following recovery?” differed significantly between level of competition groups [X2(30, N=92) = 53.30, p = 0.006]. The most frequent response for those involved in international level competition was “decrease performance immediately post-CWI, but increased performance several hours later or on subsequent days” (n = 12, 40%); while those in the national group were more likely to respond “yes” (n = 11, 38%), the most common response from the non-competitive group was “don’t know” (n = 5, 56%).