Purpose: To evaluate the effectiveness between cold-water immersion (CWI) and phase-change-material (PCM) cooling on intramuscular, core, and skin-temperature and cardiovascular responses. Methods: In a randomized, crossover design, 11 men completed 15 min of 15°C CWI to the umbilicus and 2-h recovery or 3 h of 15°C PCM covering the quadriceps and 1 h of recovery, separated by 24 h. Vastus lateralis intramuscular temperature at 1 and 3 cm, core and skin temperature, heart-rate variability, and thermal comfort were recorded at baseline and 15-min intervals throughout treatment and recovery. Results: Intramuscular temperature decreased (P < .001) during and after both treatments. A faster initial effect was observed from 15 min of CWI (Δ: 4.3°C [1.7°C] 1 cm; 5.5°C [2.1°C] 3 cm; P = .01). However, over time (2 h 15 min), greater effects were observed from prolonged PCM treatment (Δ: 4.2°C [1.9°C] 1 cm; 2.2°C [2.2°C] 3 cm; treatment × time, P = .0001). During the first hour of recovery from both treatments, intramuscular temperature was higher from CWI at 1 cm (P = .013) but not 3 cm. Core temperature deceased 0.25° (0.32°) from CWI (P = .001) and 0.28°C (0.27°C) from PCM (P = .0001), whereas heart-rate variability increased during both treatments (P = .001), with no differences between treatments. Conclusions: The magnitude of temperature reduction from CWI was comparable with PCM, but intramuscular temperature was decreased for longer during PCM. PCM cooling packs offer an alternative for delivering prolonged cooling whenever application of CWI is impractical while also exerting a central effect on core temperature and heart rate.
Susan Y. Kwiecien, Malachy P. McHugh, Stuart Goodall, Kirsty M. Hicks, Angus M. Hunter, and Glyn Howatson
Tom Clifford, Will Abbott, Susan Y. Kwiecien, Glyn Howatson, and Malachy P. McHugh
Purpose : To examine whether donning lower-body garments fitted with cooled phase change material (PCM) would enhance recovery after a soccer match. Methods : In a randomized, crossover design, 11 elite soccer players from the reserve squad of a team in the second-highest league in England wore PCM cooled to 15°C (PCMcold) or left at ambient temperature (PCMamb; sham control) for 3 h after a soccer match. To assess recovery, countermovement jump height, maximal isometric voluntary contraction (MIVC), muscle soreness, and the adapted Brief Assessment of Mood Questionnaire (BAM+) were measured before 12, 36, and 60 h after each match. A belief questionnaire was completed preintervention and postintervention to determine the perceived effectiveness of each garment. Results : Results are comparisons between the 2 conditions at each time point postmatch. MIVC at 36 h postmatch was greater with PCMcold versus PCMwarm (P = .01; ES = 1.59; 95% CI, 3.9–17.1%). MIVC also tended to be higher at 60 h postmatch (P = .05; ES = 0.85; 95% CI, −0.4% to 11.1%). Muscle soreness was 26.5% lower in PCMcold versus PCMwarm at 36 h (P = .02; ES = 1.7; 95% CI, −50.4 to −16.1 mm) and 24.3% lower at 60 h (P = .04; ES = 1.1; 95% CI, −26.9 to −0.874 mm). There were no between-conditions differences in postmatch countermovement jump height or BAM+ (P > .05). The belief questionnaire revealed that players felt the PCMcold was more effective than the PCMamb after the intervention (P = .004). Conclusions : PCM cooling garments provide a practical means of delivering prolonged postexercise cooling and thereby accelerate recovery in elite soccer players.
Malachy P. McHugh, Tom Clifford, Will Abbott, Susan Y. Kwiecien, Ian J. Kremenic, Joseph J. DeVita, and Glyn Howatson
Purpose: To assess the utility of an inertial sensor for assessing recovery in professional soccer players. Methods: In a randomized, crossover design, 11 professional soccer players wore shorts fitted with phase change material (PCM) cooling packs or uncooled packs (control) for 3 h after a 90-min match. Countermovement jump (CMJ) performance was assessed simultaneously with an inertial sensor and an optoelectric system: prematch and 12, 36, and 60 h postmatch. Inertial sensor metrics were flight height, jump height, low force, countermovement distance, force at low point, rate of eccentric force development, peak propulsive force, maximum power, and peak landing force. The only optoelectric metric was flight height. CMJ decrements and the effect of PCM cooling were assessed with repeated-measures analysis of variance. Jump heights were also compared between devices. Results: For the inertial sensor data, there were decrements in CMJ height on the days after matches (88% [10%] of baseline at 36 h, P = .012, effect size = 1.2, for control condition) and accelerated recovery with PCM cooling (105% [15%] of baseline at 36 h, P = .018 vs control, effect size = 1.1). Flight heights were strongly correlated between devices (r = .905, P < .001), but inertial sensor values were 1.8 [1.8] cm lower (P = .008). Low force during countermovement was increased (P = .031) and landing force was decreased (P = .043) after matches, but neither was affected by the PCM cooling intervention. Other CMJ metrics were unchanged after matches. Conclusions: This small portable inertial sensor provides a practical means of assessing recovery in soccer players.