Prolonged cooling for exercise recovery: A novel use for phase change material

Strenuous exercise can result in structural damage to the skeletal muscle. Muscle damage, which can be experienced by both recreational and elite athletes, is accompanied by signs and symptoms such as strength loss, and increases in soreness, oxidative stress, and inflammation. If excessive or unabated muscle damage can result in performance decrements. Hence, accelerating recovery has been the focus of much research. Cryotherapy has become an increasingly popular recovery modality for its purported ability to reduce blood flow, metabolism and the inflammatory response at the site of the muscle damage. Cold water immersion (CWI) is most commonly used following exercise for reducing muscle soreness, but evidence to support its use for accelerating recovery of strength loss, muscle damage, or inflammation remains conflicting. All cryotherapy modalities are limited in their duration of application. Phase change material (PCM), a novel cryotherapy modality, is capable of overcoming this limitation by extending the duration of treatment for longer than other more traditional cryotherapy modalities. Thus, PCM might present a practical alternative to CWI as a recovery modality. However, the application of PCM for accelerating recovery from exercise has not been examined. Therefore, this course of investigation aimed to elucidate the effects of PCM on recovery from strenuous exercise. Firstly, this research focused on determining the efficacy of prolonged PCM cooling for recovery from mechanically and metabolically stressful exercise. Secondly, the effects of prolonged PCM cooling on intramuscular, core temperature, and the cardiovascular response were determined and compared with a CWI protocol. Finally, this research investigated whether PCM cooling blunted the acute adaptive response to eccentric exercise, following a repeated bout of exercise. Study 1: This study established the proof of concept that wearing a garment fitted with PCM at a temperature of 15°C administered to the quadriceps for 6 hours could improve recovery from damaging eccentric exercise. The PCM treatment was effective in accelerating recovery of strength loss and soreness. Results also demonstrated that prolonged PCM cooling accelerated recovery of these variables in the leg that did not directly receive PCM cooling. This finding suggested that prolonged PCM cooling might deliver a systemic, and not just a local effect. Study 2: This investigation examined the efficacy of PCM as a recovery intervention following exercise with a large metabolic component (a marathon run). Unlike the results from Study 1, recovery of strength loss and perceived soreness were not accelerated from 3 hours of PCM cooling. The results also indicated that PCM cooling was not effective in accelerating recovery of vertical jump height, or blood markers of muscle damage or systemic inflammation. Study 3: This study determined the effects of 3 hours of PCM cooling and 15 minutes of CWI controlled for treatment temperature (15°C PCM and 15 ± 1°C CWI) on intramuscular-, core-, skin-temperature and cardiovascular responses. Although the magnitude of temperature reduction from both PCM and CWI was comparable, PCM maintained a reduction in intramuscular temperature throughout the duration of application. This study also confirmed that, during application, both modalities exerted a central effect on core temperature and heart rate (HR). These effects on core temperature and HR suggested that the effect observed from indirect PCM cooling in Study 1 was a true systemic effect. Study 4: The final study of this thesis expanded on the findings of the pilot study, by repeating the same exercise protocol 2 weeks later, in order to examine whether acute adaptation (the repeated bout effect; RBE) was influenced by the PCM intervention. In contrast to the first investigation, the PCM were applied to both legs in the treatment condition, and blood markers of muscle damage and inflammation were additionally measured. The results demonstrated that PCM cooling accelerated recovery of strength, soreness, and the blood marker of muscle damage, but not inflammation. Importantly, despite accelerating recovery following the first bout of exercise, PCM did not inhibit the RBE. The series of investigations encompassing this thesis have established support for the use of prolonged PCM cooling in accelerating recovery from exercise of a mechanical nature. Further, this thesis provides new additions to the literature on the novel application of PCM as a recovery modality for accelerating recovery of strength loss without inhibiting the adaptive response to exercise

The efficacy of cooling with phase change material for the treatment of exercise-induced muscle damage: pilot study

Post-exercise cryotherapy treatments are typically short duration interventions. This study examined the efficacy of prolonged cooling using phase change material (PCM) on strength loss and pain after eccentric exercise. Eight adults performed 120 bilateral eccentric quadriceps contractions (90% MVC). Immediately afterwards, frozen PCM packs (15°C) were placed over the quadriceps, with room temperature PCM packs on the contralateral quadriceps. Skin temperature was recorded continually (6 h PCM application). Isometric quadriceps strength and soreness were assessed before, 24, 48, 72 and 96 h post-exercise. The protocol was repeated 5 months later, with room temperature PCM applied to both legs. There were three treatments: legs treated with 15°C PCM packs (direct cooling), legs treated with room temperature PCM packs contralateral to the 15°C PCM packs (systemic cooling), and legs tested 5 months later both treated with room temperature PCM packs (control). Skin temperature was 9°C–10°C lower with direct cooling versus systemic cooling and control (P < 0.01). Strength loss and soreness were less (P < 0.05) with direct cooling versus systemic cooling and control (strength 101%, 94%, 93%, respectively; pain 1.0, 2.3, 2.7, respectively). Six hours of PCM cooling was well tolerated and reduced strength loss and pain after damaging exercise

Don't Lose Your Cool with Cryotherapy: the application of phase change material for prolonged cooling in athletic recovery and beyond

Strenuous exercise can result in muscle damage in both recreational and elite athletes, and is accompanied by strength loss, and increases in soreness, oxidative stress, and inflammation. If the aforementioned signs and symptoms associated with exercise-induced muscle damage are excessive or unabated, the recovery process becomes prolonged and can result in performance decrements; consequently, there has been a great deal of research focussing on accelerating recovery following exercise. A popular recovery modality is cryotherapy which results in a reduction of tissue temperature by the withdrawal of heat from the body. Cryotherapy is advantageous because of its ability to reduce tissue temperature at the site of muscle damage. However, there are logistical limitations to traditional cryotherapy modalities, such as cold-water immersion or whole-body cryotherapy, because they are limited by the duration for which they can be administered in a single dose. Phase change material (PCM) at a temperature of 15°C can deliver a single dose of cooling for a prolonged duration in a practical, efficacious, and safe way; hence overcoming the limitations of traditional cryotherapy modalities. Recently, 15°C PCM has been locally administered following isolated eccentric exercise, a soccer match, and baseball pitching, for durations of three to six hours with no adverse effects. These data showed that using 15°C PCM to prolong the duration of cooling successfully reduced strength loss and soreness following exercise. Extending the positive effects associated with cryotherapy by prolonging the duration of cooling can enhance recovery following exercise and give athletes a competitive advantage

Countermovement Jump Recovery in Professional Soccer Players Using an Inertial Sensor

Purpose The purpose of this study was 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 minute match. Countermovement jump (CMJ) performance was assessed simultaneously with an inertial sensor and an optoelectric system, pre match, and 12, 36 and 60 h post match. 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 effect of PCM cooling were assessed with repeated measures ANOVA. 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=0.012, effect size 1.2, for control condition) and accelerated recovery with PCM cooling (105±15% of baseline at 36 h, P=0.018 vs. control, effect size 1.1). Flight heights were strongly correlated between devices (r=0.905, P<0.001) but inertial sensor values were 1.8±1.8 cm lower (P=0.008). Low force during countermovement was increased (P=0.031) and landing force was decreased (P=0.043) after matches, but neither were 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

Accelerated muscle recovery in baseball pitchers using phase change material cooling

Purpose: The purpose of this study was to document recovery following a pitching performance and determine if prolonged post-game phase change material (PCM) cooling of the shoulder and forearm accelerates recovery. Methods: Strength, soreness and serum creatine kinase (CK) activity were assessed prior to, and on the two days following pitching performances in 16 college pitchers. Pitchers were randomized to receive either post-game PCM cooling packs on the shoulder and forearm, or no cooling (control). PCM packs were applied inside compression shirts and delivered cooling at a constant temperature of 15°C for 3 hours. Strength was assessed for shoulder internal rotation (IR), external rotation (ER), empty can test (EC) and grip. Results: Total pitch count was 60±16 for 23 PCM cooling games and 62±17 for 24 control games (P=.679). On the days following pitching IR strength (P=.006) and grip strength (P=.036) were higher in the PCM cooling group versus control. One day after pitching IR strength was 95±14 of baseline with PCM cooling versus 83±13 for control (P=.008, effect size d 0.91) and 107±9 versus 95±10 for grip strength (P=.022, effect size d 1.29). There was a trend for greater ER strength with PCM cooling (P=.091, effect size d 0.51). The EC strength was not impaired after pitching (P=.147) and was therefore unaffected by PCM cooling (P=.168). Elevations in soreness and CK were not different between treatments (Treatment by Time CK P=.139, shoulder soreness P=.885, forearm soreness P=.206). Conclusion: This is one of the first studies to document impairments in muscle function on the days following baseball pitching, and the first study showing a novel cryotherapy intervention that accelerates recovery of muscle function in baseball pitchers following a game

Cold for centuries: a brief history of cryotherapies to improve health, injury and post-exercise recovery

For centuries, cold temperatures have been used by humans for therapeutic, health and sporting recovery purposes. This application of cold for therapeutic purposes is regularly referred to as cryotherapy. Cryotherapies including ice, cold-water and cold air have been popularised by an ability to remove heat, reduce core and tissue temperatures, and alter blood flow in humans. The resulting downstream effects upon human physiologies providing benefits that include a reduced perception of pain, or analgesia, and an improved sensation of well-being. Ultimately, such benefits have been translated into therapies that may assist in improving post-exercise recovery, with further investigations assessing the role that cryotherapies can play in attenuating the ensuing post-exercise inflammatory response. Whilst considerable progress has been made in our understanding of the mechanistic changes associated with adopting cryotherapies, research focus tends to look towards the future rather than to the past. It has been suggested this might be due to the notion of progress being defined as change over time from lower to higher states of knowledge (Lawrence, 1984). However, a historical perspective, studying a subject in light of its earliest phase and subsequent evolution, could help sharpen one’s vision of the present; helping to generate new research questions as well as look at old questions in new ways (Lawrence, 1984). Therefore, the aim of this brief historical perspective is to highlight the origins of the many arms of this popular recovery and treatment technique, whilst further assessing the changing face of cryotherapy

Is it the End of the Ice Age?

The use of the RICE (Rest, Ice, Compression, Elevation) protocol has been the preferred method of treatment for acute musculoskeletal injuries for decades. However, the efficacy of using ice as a recovery strategy following injury in humans remains uncertain, and there is a growing trend recommending against icing following injury. Animal models suggest that while ice can help to accelerate the recovery process, extreme muscle cooling might delay repair and increase muscle scarring. Despite the conflicting evidence, ice should not be dismissed as a potential treatment option. When considering what is known about the injury cascade, the optimal application window for ice is in the immediate acute stage following injury to reduce the proliferation of secondary tissue damage that occurs in the hours after the initial injury. Practitioners should tailor the application of ice based on the injury timeline and repair process, consistent with applications in 20-30 minute intervals within the first 12 hours post-injury. Until the evidence unanimously proves otherwise, the culture of icing injuries should remain a staple in sports medicine

Cryotherapy re-invented: application of phase change material for recovery in elite soccer

Purpose: This study examined 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, eleven elite soccer players from the reserve squad of a team in the 2nd highest league in England wore PCM cooled to 15°C (PCMcold) or left at ambient temperature (PCMamb) for 3 h after a soccer match. To assess recovery, countermovement jump (CMJ) height, maximal isometric voluntary contraction (MIVC), muscle soreness (MS), and the adapted Brief Assessment of Mood Questionnaire (BAM+) were measured before, 12, 36 and 60 h after each match. Pre and post intervention, a belief questionnaire (BFQ) was completed to determine perceived effectiveness of each garment. Results: Results are comparisons between the two conditions at each time point post-match. MIVC at 36 h post was greater with PCMcold vs. PCMwarm (P=0.005; ES=1.59; 95% CI=3.9 to 17.1%). MIVC also tended to be higher at 60 h post (P=0.051; ES=0.85; 95% CI= −0.4 to 11.1%). MS was 26.5% lower in PCMcold vs. PCMwarm at 36 h (P=0.02; ES=1.7; 95% CI= −50.4 mm to −16.1 mm) and 24.3% lower at 60 h (P=0.039; ES=1.1; 95% CI= −26.9 mm to −0.874 mm). There were no between condition differences in post-match CMJ height or BAM+ (P>0.05). The BFQ revealed that players felt the PCMcold was more effective than the PCMamb after the intervention (P=0.004). Conclusions: PCM cooling garments provide a practical means of delivering prolonged post exercise cooling and thereby accelerating recovery in elite soccer players

Prolonged cooling with phase change material enhances recovery and does not affect the subsequent repeated bout effect following exercise

PURPOSE: The aim of this investigation was two-fold: (1) to examine the effect of prolonged phase change material(PCM) cooling following eccentric exercise of the quadriceps on indices of muscle damage, and (2) to elucidatewhether application of PCM cooling blunted the acute adaptive response to eccentric exercise, known as therepeated bout effect (RBE).METHODS: Twenty-six males (25±6 years) performed an initial bout (B1) of 120 eccentric quadriceps contractionson each leg at 90% of their isometric strength and were then randomized to receive PCM packs frozen at 15°C(treatment) or melted packs (control) worn directly on the skin under shorts for 6 h. The protocol was repeated 14days later (B2) with all participants receiving the control condition.RESULTS: PCM cooling provided protection against strength loss in B1 (P=0.005) with no difference in strengthbetween treatment groups in B2 (P=0.172; bout by treatment by time P=0.008). PCM cooling reduced soreness inB1 (P=0.009) with no difference between treatment groups in B2 (P=0.061). Soreness was overall lower followingB2 than B1 (P<0.001). CK was elevated in B1 (P<0.0001) and reduced in B2 (P<0.001) with no difference betweentreatments. The damage protocol did not elevate hsCRP in B1, with no difference between treatments or betweenbouts.CONCLUSIONS: This work provides further evidence that PCM cooling enhances recovery of strength and reducessoreness following eccentric exercise. Importantly, these data show for the first time that prolonged PCM coolingdoes not compromise the adaptive response associated with the RBE

Primo Levi: l’eroe e i mostri dell’immaginario tecnologico,

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 males 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<0.001) during and after both treatments. A faster initial effect was observed from 15 min of CWI (Δ: 4.3±1.7°C 1 cm; 5.5±2.1°C 3 cm; P=0.01). However, over time (2 h 15 min), greater effects were observed from prolonged PCM treatment (Δ: 4.2±1.9°C 1 cm; 2.2±2.2°C 3 cm; treatment × time P=0.0001). During the first hour of recovery from both treatments, intramuscular temperature was higher from CWI at 1 cm (P=0.013) but not 3 cm. Core temperature deceased 0.25±0.32 from CWI (P=0.001) and 0.28±0.27°C from PCM (P=0.0001) while heart rate variability increased during both treatments (P=0.001), with no differences between treatments. Conclusions: The magnitude of temperature reduction from CWI was comparable to PCM but intramuscular temperature was decreased for longer during PCM. Utilizing PCM cooling packs offers an alternative for delivering prolonged cooling whenever application of CWI is impractical while also exerting a central effect on core temperature and heart rate