Accelerated Muscle Recovery in Baseball Pitchers Using Phase Change Material Cooling

Investigating the effect of phase change materials on the viability of damaged tissue in disarticulated limbs

BACKGROUND

This study developed a temperature-controlled transport preservation box for severed limb tissues using phase change material (PCM) as the main source to solve the problem of inconvenient preservation of trauma and severed tissues under emergency conditions. The goal of this study is to extend the time window for treatment of severed limb casualties and reduce the rate of disability and teratogenicity.

METHODS

In this study, after successfully establishing an animal model of severed limb injury in rats, the rats were divided into experimental and control groups. The rats in the control group were given emergency bandaging of the severed limbs and then reimplanted, while the rats in the experimental group were placed in the PCM preservation box at 4℃, 8℃, 12℃, and 16℃, and then the limbs were reimplanted. The PCM was subjected to temperature control test, thermal conductivity test, and DSC test at the four test temperatures. The biochemical indices, histological HE and PTAH staining, and ultrastructural observation by transmission electron microscopy were performed at the four test temperatures to evaluate the damage and degeneration of the severed limb tissues.

RESULTS AND CONCLUSIONS

The PCM had good material and thermal properties at the four test temperatures. The control group was more damaged than the test group in terms of biochemical factor expression, histologic degeneration, and ultrastructural changes. Considering the material and thermal properties, cell structure changes, and cell physiological status, the 8℃ test group shows excellent potential for clinical application and lays a solid foundation for further clinical application in the future.

Fatigue of the Dynamic Stabilizers of the Medial Elbow in Baseball Pitchers

Background

The flexor carpi ulnaris and flexor digitorum superficialis are thought to provide dynamic stability to the medial elbow during pitching. High medial elbow stress during pitching fatigues these dynamic stabilizers of the medial elbow. This fatigue of dynamic stabilizers could leave the ulnar collateral ligament more vulnerable to the stress of pitching.

Purpose/Hypothesis

The purpose of this study was to identify the onset of fatigue in the dynamic elbow stabilizers during a pitching performance. It was hypothesized that middle finger (MF) and ring finger (RF) fatigue during a pitching performance would occur earlier and be more substantial than grip and 3 finger grip fatigue.

Study Design

Descriptive laboratory study.

Methods

Eighteen baseball pitchers (age, 17 ± 4 years) threw 4 innings of a simulated game (16 pitches per inning plus 5 warm-up pitches per inning). Before the game and after each inning, MF flexion, RF flexion, and grip strength were recorded. A standard full grip (FG) and a modified 3-finger grip (3FG) test were employed. Fatigue was classified as marked (>20% loss), moderate (10%-20% loss) or minimal (<10% loss).

Results

MF strength was greater on the dominant versus nondominant hand (7%; P = .04). There was no hand dominance effect for the other 3 tests (RF, P = .15; FG, P = .79; 3FG, P = .90). The fatigue responses differed significantly between tests (P < .001). After the fourth inning, MF fatigue (21%) was greater than RF (7%; P < .001), FG (5%; P < .002), and 3FG (5%; P < .001) fatigue. MF fatigue was evident early and was progressive. After the first inning, 4 pitchers (22%) had marked MF fatigue and 3 (17%) had moderate MF fatigue. By the end of the fourth inning, 10 pitchers (56%) had marked MF fatigue and 6 (33%) had moderate MF fatigue. By contrast, only 5 pitchers (28%) had marked RF fatigue after 4 innings, and only 3 pitchers (17%) had marked FG or 3FG fatigue. Pitchers with high valgus elbow torque during pitching had greater MF fatigue than pitchers with lower elbow valgus forces (22% vs 10%; P = .045).

Conclusion

By the end of the fourth inning, 10 pitchers (56%) had marked MF fatigue and 6 (33%) had moderate MF fatigue. MF fatigue may be indicative of medial elbow dynamic stabilizer fatigue in pitchers.

Clinical Relevance

We recommend finger flexor strength training to help support the medial stabilizers of the elbow during pitching. In the future, MF fatigue testing could be an "in-game" measure of pitcher fatigue.

Pool-Based Surfboard Elicits Activation of Posterior Shoulder Muscles During a Surfing Stroke

ABSTRACT

Pexa, BS, Johnston, CD, Elder, EE, Ford, KR, Patterson, MQ, and Myers, JB. Pool-based surfboard elicits activation of posterior shoulder muscles during a surfing stroke. J Strength Cond Res 38(7): 1300-1304, 2024-Surfboard paddling may activate posterior shoulder muscles, which are critical to baseball pitchers' injury risk and performance. The purpose of this study was to measure posterior shoulder muscle activation during different phases of the surf stroke (propulsion vs. recovery) on a pool-based surfboard. Twenty healthy active adult subjects completed a familiarization and testing session with the pool-based surfboard. During the testing session, electromyography (EMG) sensors were placed on 6 posterior shoulder muscles: latissimus dorsi, infraspinatus, posterior deltoid, upper trapezius, middle trapezius, and lower trapezius. Subjects completed 4 laps in a pool at 3 separate resistances (low, moderate, and heavy) in a randomized order. The peak EMG signal during each phase (propulsion and recovery) was recorded. A 2-way within subject ANOVA (resistance-by-phase) with post hoc Bonferroni's corrections was used to identify differences in EMG activation. There was a significant main effect of phase for the latissimus dorsi (F = 91.3, p < 0.001), upper trapezius (F = 36.5, p < 0.001), middle trapezius (F = 33.8, p < 0.001), and lower trapezius (F = 21.6, p < 0.001). The latissimus dorsi demonstrated higher activation during the propulsion phase (p < 0.001), and all trapezius muscles demonstrated higher activation during the recovery phase (p < 0.001). There was a significant main effect of resistance for the posterior deltoid (F = 3.4, p = 0.043), with higher muscle activation in the low resistance trials compared with the heavy resistance trials (p = 0.036). Recreationally active individuals demonstrate activation of the posterior shoulder when using a pool-based surfboard. This pool-based surfboard may be beneficial to activate the posterior musculature and may be more accessible than standard surfing to baseball athletes.

Does High Medial Elbow Stress During Pitching Compromise the Dynamic Stabilizers of The Elbow?

Background

The flexor carpi ulnaris (FCU) and flexor digitorum superficialis (FDS) are thought to provide dynamic stability to the medial elbow, with a lesser contribution from the pronator teres (PT).

Hypothesis/Purpose

The purpose of this study was to determine if baseball pitchers with higher valgus elbow torque experience greater FCU and FDS strength loss.

Study Design

Controlled Laboratory Study.

Methods

A pilot study was performed to determine if middle and ring finger flexion strength tests preferentially activated the FCU and FDS versus the PT (10 men age 36±12 yr). EMG amplitudes, expressed as percent of maximal voluntary contraction (MVC) were compared between tests and muscles. In a field study of college baseball pitchers, middle finger, ring finger and grip strength were tested prior to, immediately after, and one day after 14 pitching performances in 10 pitchers (21±2 yr). Elbow valgus torque was measured from an inertial measurement unit, housed in a compression sleeve and pitchers were categorized as having high or low valgus torque.

Results

For the pilot study EMG activations were 74% FDS, 66% FCU and 35% PT for the middle finger test (muscle effect p=0.032) and 93% FCU, 61% FDS and 23% PT for the ring finger test (muscle effect p=0.005). In the field study, pitchers with high valgus torque showed marked post-game middle finger fatigue (88% of baseline) and incomplete recovery the following day (95%), while pitchers with low valgus torque showed no strength loss (107% post game, 106% a day later; group x time p=0.022). Results were similar for ring finger strength (high torque: 94% post game 96% a day later; low torque: 114% post game 107% a day later; group x time p=0.048). By contrast, grip strength was not different between pitchers with high versus low valgus torque (p=0.143).

Conclusion

High medial elbow stress during pitching fatigues the dynamic stabilizers of the medial elbow.

Level of Evidence

Level 3©The Author(s).

Phase-change material cooling blanket: A feasible cooling choice during transport after exercise-induced hyperthermia

BACKGROUND

Exercise-induced hyperthermia preceding the onset of exertional heatstroke requires a rapid reduction in the body core temperature (T_core) to ensure safety. In recent years, phase-change material (PCM) cooling devices have been increasingly used for rapid cooling after hyperthermia due to their superior capacity for heat absorption.

OBJECTIVES

This study aimed to evaluate the cooling performance and effectiveness of a PCM cooling blanket on heart rate (HR) and heart rate variability (HRV) recovery after exercise-induced hyperthermia.

DESIGN

Randomized cross-over.

METHODS

The study participants were 12 male volunteers who were engaged in professional training and completed an endurance exercise for approximately 30 min in a hot and humid environment (temperature ≈ 30 °C; relative humidity ≈ 66%). The participants underwent a 30-min cooling trial after exercise, receiving either treatment with a PCM cooling blanket (PCM group) or natural cooling (CON group). The T_core, HR, and HRV time-domain indices were used for analysis.

RESULTS

The T_core values were significantly lower in the PCM group during cooling. Reductions in the T_core from precooling to 20 min of cooling were significantly greater in the PCM group than in the CON group. The HR in the PCM group was lower than that recorded in the CON group at 10 and 20 min of cooling. The reduction in HR during cooling from precooling was also significantly greater in the PCM group. HRV time-domain indices during cooling in the PCM group were significantly lower compared with the CON group while elevations in some HRV time-domain indices from precooling to postcooling were significantly greater in the PCM group than in the CON group.

CONCLUSIONS

The PCM cooling blanket had good cooling performance and the ability to hasten recovery of both HR and HRV. It may serve as a feasible cooling choice during transport after exercise-induced hyperthermia.

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 that this might be due to the notion of progress being defined as change over time from lower to higher states of knowledge. 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. 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. We conclude by discussing what lies ahead in the future for cold-application techniques.

The cold truth: the role of cryotherapy in the treatment of injury and recovery from exercise

Cryotherapy is utilized as a physical intervention in the treatment of injury and exercise recovery. Traditionally, ice is used in the treatment of musculoskeletal injury while cold water immersion or whole-body cryotherapy is used for recovery from exercise. In humans, the primary benefit of traditional cryotherapy is reduced pain following injury or soreness following exercise. Cryotherapy-induced reductions in metabolism, inflammation, and tissue damage have been demonstrated in animal models of muscle injury; however, comparable evidence in humans is lacking. This absence is likely due to the inadequate duration of application of traditional cryotherapy modalities. Traditional cryotherapy application must be repeated to overcome this limitation. Recently, the novel application of cooling with 15 °C phase change material (PCM), has been administered for 3-6 h with success following exercise. Although evidence suggests that chronic use of cryotherapy during resistance training blunts the anabolic training effect, recovery using PCM does not compromise acute adaptation. Therefore, following exercise, cryotherapy is indicated when rapid recovery is required between exercise bouts, as opposed to after routine training. Ultimately, the effectiveness of cryotherapy as a recovery modality is dependent upon its ability to maintain a reduction in muscle temperature and on the timing of treatment with respect to when the injury occurred, or the exercise ceased. Therefore, to limit the proliferation of secondary tissue damage that occurs in the hours after an injury or a strenuous exercise bout, it is imperative that cryotherapy be applied in abundance within the first few hours of structural damage.

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 3-6 h 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.