Rev Bras Fisiol Exerc 2020;19(4):283-91

doi: 10.33233/rbfex.v19i4.3925

ORIGINAL ARTICLE

The effects of immersion cryotherapy on levels of muscle strength and power

Efeito da crioterapia de imersão sobre níveis de força e potência muscular

 

Júlia da Silveira Gross1, André Luiz Lopes1,2, Renata Lopes Krüger1, Gustavo dos Santos Ribeiro2,3, Régis Radaelli1, Randhall Bruce Kreismann Carteri1, Bruno Costa Teixeira1,4, Álvaro Reischak-Oliveira1

 

1Programa de Pós-Graduação em Ciências do Movimento Humano, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brasil

2Instituto Sul-Brasileiro de Curso e Qualificações, Faculdades QI, Porto Alegre, RS, Brasil

3Programa de Pós-Graduação em Ciências da Reabilitação, Universidade Federal de Ciências da Saúde de Porto Alegre, Porto Alegre, RS, Brasil

4Universidade Regional Integrada do Alto Uruguai e das Missões, São Luiz Gonzaga, RS, Brasil

 

Received on: February 6, 2020; Accepted on: July 27, 2020.

Corresponding author: André Luiz Lopes, Laboratório de Pesquisa do Exercício (LAPEX), Rua Felizardo, 750 Jardim Botânico 90035-003 Porto Alegre RS, Brasil

 

Júlia da Silveira Gross: juliasgross@hotmail.com

André Luiz Lopes: andregym23@gmail.com

Renata Lopes Krüger: renatalkruger@gmail.com

Gustavo dos Santos Ribeiro: gustavosr@ufcspa1.onmicrosoft

Régis Radaelli: regis.radaelli@hotmail.com

Randhall Bruce Kreismann Carteri: rcarteri@outlook.com

Bruno Costa Teixeira: brunoct100@hotmail.com

Álvaro Reischak-Oliveira: alvaro.oliveira@ufrgs.br

 

Abstract

Aims: To verify the influence of immersion cryotherapy on isometric strength and lower limb power of athletes. Methods: Using a cross-sectional crossover design, 14 rugby athletes underwent three laboratory visits. The first visit was composed of anthropometric (mass, height, and body composition), aerobic capacity (cardiopulmonary exercise test), and dietary assessments. On the second and third visits, vertical jump and isometric peak torque of the knee extensors were assessed in three moments: 1) at baseline; 2) after fatigue protocol; and 3) after recovery protocol: active rest or immersion cryotherapy. Fatigue protocol was composed by running at a speed corresponding to 120% of VO2MAX until voluntary fatigue. To immersion cryotherapy, all subjects had their lower limbs immersed in a tank with ice and water (10 ± 1°C), remaining in the standing position for 10 minutes. For active recovery, subjects were standing in an empty tank. Data were analyzed on GraphPAD Prism (p < 0.05). Results: Fourteen rugby athletes (age 22 ± 2 years; fat mass 27.8 ± 4.4%; VO2MAX 44.1 ± 6.7 ml.kg-1.min-1) were evaluated. There was no difference in caloric intake among the evaluation days (2,893 ± 802 versus 2,915 ± 746 kcal; p = 0.949). Jump height reduced 18% after fatigue and immersion cryotherapy protocols (33.0 ± 2.8 versus 27.0 ± 2.8 cm; p < 0.05) and a 7.1% increase after fatigue and active rest (32.5 ± 6.4 versus 34.8 ± 2.1 cm; p < 0.05). Regarding the isometric peak torque, it was reduced by 3.7% after immersion cryotherapy (295 ± 71 versus 285 ± 68 Nm; p<0.05) and 9.6% after active rest (297 ± 73 versus 268 ± 72 Nm; p < 0.05). Conclusion: Immersion cryotherapy seems to affect lower limb power albeit could assist in the recovery of isometric strength compared to passive recovery. This information is important to compose recovery protocols for specific tasks.

Keywords: physical therapy specialty; cryotherapy; recovery of function; regeneration; muscle strength; athletic performance; exercise.

 

Resumo

Objetivos: Verificar a influência da crioterapia de imersão na força isométrica e potência de membros inferiores de atletas. Métodos: Neste estudo transversal do tipo crossover, 14 sujeitos foram avaliados em três momentos. Primeiro realizaram os testes de caracterização: antropometria (massa, estatura e composição corporal), capacidade aeróbia (teste de esforço cardiopulmonar) e recordatório alimentar. Na segunda e na terceira visita foram ministrados os testes de impulsão vertical em tapete de contato e o pico de torque isométrico da musculatura extensora de joelhos no CYBEX isocinético. Estes testes foram realizados em três momentos: 1) em situação basal; 2) após o protocolo de fadiga; e 3) após o protocolo de recuperação: repouso ativo ou crioterapia de imersão. O protocolo de fadiga incidia em correr na velocidade correspondente a 120% do VO2MAX até a falha motora. Para a crioterapia de imersão, os sujeitos submergiram os membros inferiores até o nível das gônadas em um tanque contendo gelo e água, permanecendo na posição ortostática por 10 minutos. A temperatura da água foi monitorada utilizando um termômetro subaquático (10 ± 1°c). Para recuperação ativa, os sujeitos repetiram o procedimento em um tanque vazio. Os dados foram analisados no GraphPAD Prism (p < 0,05). Resultados: Foram avaliados 14 atletas de rúgbi (idade 22 ± 2 anos; massa adiposa 27,8 ± 4,4%; VO2MAX 44,1 ± 6,7 ml.kg-1.min-1). Não houve diferença no consumo calórico entre os dias de avaliação (2.893 ± 802 versus 2.915 ± 746 kcal; p = 0,949). Nossos dados indicam redução de 18% na altura do salto após os protocolos de fadiga e crioterapia (33,0 ± 2,8 versus 27,0 ± 2,8 cm; p < 0,05) e incremento de 7,1% após os protocolos de fadiga e repouso (32,5 ± 6,4 versus 34,8 ± 2,1 cm; p < 0,05). Em relação ao pico de torque isométrico, observou-se redução de 3,7% após a crioterapia (295 ± 71 versus 285 ± 68 Nm; p < 0,05) e de 9,6% após o repouso ativo (297 ± 73 versus 268 ± 72 Nm; p < 0,05). Conclusão: A crioterapia de imersão parece afetar a potência de membros inferiores e auxiliar na recuperação da força isométrica quando comparada a recuperação passiva.

Palavras-chave: Fisioterapia; crioterapia; recuperação de função fisiológica; regeneração; força muscular; desempenho atlético; exercício.

 

 

Introduction

 

Cryotherapy is a technique often used in sports medicine to treat musculoskeletal injuries or accelerate the athletes' recovery [1]. Immersion cryotherapy consists of submerging the whole body or body segment in a container with combined water and ice for a predetermined time. Bleakley et al. [2] mention that the temperature resulting from this combination can vary from 10 to 15ºC, although some studies have used colder temperatures [3]. Regarding the exposure time, continuous (5 to 24 minutes) or intermittent (2 to 15 minutes) protocols are used to cool body tissues aiming to minimize inflammation in muscles and joints [1].

From a physiological point of view, the application of cold stimulates skin receptors causing the sympathetic activation of muscle fibers, reducing the hemorrhagic condition when reaching 13.8ºC. The lower local blood flow stimulates the metabolic rate reduction and, consequently, the oxygen demand and cell death risk due to secondary necrosis [1,4]. Besides, Herrera et al. [5] hypothesized a relationship between temperature and nerve conduction, mainly in the more superficial nerves. These authors argue that the conduction speed of motor nerves has a direct relationship with tissue temperature reduction, affecting muscle strength and power production.

In this sense, Pritchard & Saliba [6] showed cryotherapy applied by small intervals does not interfere negatively in the performance of vertical jump, agility tests, and sprints. Contrarily, Douris et al. [7], Howatson et al. [8] and Sellwood et al. [9] observed that cryotherapy applied before strength training can decrease muscle performance and potentially increase injury risks due to longer duration of the action potential and lower impulse transmission speed, causing a reduction in muscle contraction speed. Thus, there is no consensus on whether cryotherapy before a training session would be beneficial to the athlete's performance. Therefore, this study aims to verify whether immersion cryotherapy impacts the muscle strength and power of athletes' lower limbs.

 

Methods

 

Subjects

 

Eighteen healthy male rugby athletes aged between 20-40 years old, with at least two years of experience in the sport were recruited. These athletes were intentionally selected by explaining the research objectives and procedures. The athletes could not be or have been injured in the six months preceding the evaluations and should be training regularly in their team.

All procedures were previously approved by the research ethics committee of the Federal University of Rio Grande do Sul (nº 21.708/2011), respecting the recommendations of Resolution 466/12 of the National Health Council. All participants received the guidelines relevant to the procedures of the research and signed the free and informed consent form.

Although our sample was selected intentionally, we use the data published by Rowsell et al. [10], when investigating the impact of immersion cryotherapy on the power of lower limbs in soccer players, to calculate the sample size necessary to satisfy a statistical power of 90% with 95% confidence (BioEstat 5.0, Instituto Mamirauá, Brazil). According to the sample size, the mean difference and standard deviation of lower limb power identified the minimum need for 12 subjects.

 

Methodological procedures

 

The present study is characterized as cross-sectional crossover research, using a comparative model of randomized and crossed intervention. To minimize the effects of learning in the assessments, athletes were randomized in blocks using opaque envelopes to define the order of the procedures: control or intervention (cryotherapy). All participants performed both procedures, being their control. The study design consisted of three visits to the laboratory separated for five and seven days, respectively. On the first visit, sample characterization tests were administered: anthropometric assessment, cardiopulmonary test, and food recall, in addition to the randomization process.

On the second and third visits, vertical thrust and isokinetic dynamometry tests were performed to assess the power and strength of the lower limbs in three moments: 1) in a baseline situation - before the fatigue protocol - PE; 2) after the fatigue protocol - PF; and 3) after the recovery protocol - PT: active rest (control) or immersion cryotherapy. All tests were performed in the morning by the same researcher, with a standardized interval time between the assessment procedures. Figure 1 illustrates the methodological design of the study.

 


Figure 1 - Experimental session design. A: Warm-up. B: Power and strength of lower limb assessments. C: fatigue protocol. D: recovery protocol: immersion cryotherapy or active rest (control). 1min 30sec: waiting period between procedures

 

Anthropometric assessment

 

To estimate body composition, skinfolds, bone diameters, body lengths, and perimeters were measured. For this purpose, a Harpenden scientific plicometer, a short and long caliper, a segmometer (Cescorf, Brazil), and a metal measuring tape (Sanny, Brazil), respectively, were used. All techniques followed the recommendations of the International Society for the Advancement of Kinanthropometry - ISAK [11]. An experienced anthropometrist (ISAK Level II) performed all measurements. Body mass and height were measured on a mechanical scale with a coupled stadiometer (Tânita, Brazil). Body composition was predicted by the five-component methodology [12,13].

 

Cardiopulmonary test

 

To analyze the cardiorespiratory capacity and determine the intensity of effort for the fatigue protocol, the incremental test on a treadmill (Ibramed, Brazil) with gas analysis (CPX-D, MedGraphics, Minnesota, USA) was used. The protocol started at 6 km/h, with increments of 1 km/h every minute until the participant's exhaustion or identification of the interruption criteria: 1) respiratory quotient ≥ 1.15; 2) heart rate ≥ 95% of the predicted heart rate; or 3) presence of a plateau in oxygen consumption - VO2MAX [14]. Throughout the test, the slope remained fixed at 1%. Data were collected using the breath by breath method and analyzed by two experienced evaluators. Before carrying out the tests, the gas analyzer was calibrated according to the manufacturer's recommendations.

 

Food recall

 

To avoid bias caused by caloric consumption variations in the analysis, each participant was instructed to register all drinks and food consumed in the 24 hours before the tests. Meals were described with food consumed, times, quantities in homemade measures and, when necessary, the brand of the product. For proper completion, a photographic album of homemade measures was delivered, consisting of a compilation of utensils and food portions photos, based on the Photographic Album of Portions of Food [15,16].

The 24-hour recall (R24) of the first session was returned to the participants, who were instructed to repeat the same food consumption in the 24 hours prior to the second and third sessions. Participants were instructed not to consume alcoholic beverages and/or those containing caffeine in the 24 hours prior to the tests. For the analysis of R24, the software Dietwin® (Brubins, Brazil) was used.

 

Vertical jump test

 

The power of the lower limbs related to the elastic force was evaluated by the countermovement jump (CMJ) using a contact mat that recorded the flight time of each jump (Jump Test, Hidrofit, Brazil), following the protocol of Bosco et al. [17,18]. In short, the participants were positioned standing, with their hands on their hips and their feet parallel, shoulder-width apart. At the software signal, the subjects quickly flexed their hip, knee, and ankle joints (movement like the 90° squat) to jump as high as possible. At this time, they were asked not to raise their knees or bring their legs forward. The hands should remain at the waist. Each participant performed three to five jumps, with a 30-second interval. The highest value was used for analysis.

 

Isokinetic dynamometry

 

The strength of the lower limbs was assessed by the knee extensors' isometric torque peak during the maximum test, performed on the isokinetic dynamometer positioned in the extensor chair function (CYBEX 7000, Ronkonkoma, USA) [19]. Briefly, the participants were positioned seated on the equipment (85° of hip flexion and 60° of knee flexion), stabilized by belts and bands. The lateral epicondyle of the femur was aligned with the rotation axis of the dynamometer and the mechanical arm of the equipment was adjusted for each subject, to obtain the adequate distance between the knee and the lever arm. Five maximal isometric contractions of knee extension were performed to determine the maximum strength of the athletes at an angle of 60°. Standardized verbal incentives and an interval of one minute between each attempt were provided. The highest value of the peak torque was recorded.

 

Fatigue protocol

 

The protocol for fatigue induction was performed on the same treadmill used in the cardiopulmonary test. Briefly, athletes were submitted to running at an intensity 20% higher above their maximum aerobic capacity tested, that is, they needed to run at a speed related to 120% of VO2MAX (maintaining the treadmill at 1 % inclination). The protocol ended when the athlete requested or when the researcher noticed motor failure.

 

Recovery protocol

 

Immersion cryotherapy was performed in a tank with a capacity of 100 liters, filled with 70% of its capacity with a combination of water and ice. The water temperature was monitored using an underwater thermometer (10 ± 1°C). Participants entered the tank by submerging their lower limbs to the level of the gonads, remaining in the standing position for 10 minutes [20]. A similar procedure was adopted for passive recovery (placebo), inside the tank without adding water and ice.

 

Statistical analysis

 

For data analysis, GraphPAD Prism 5 (GraphPad Inc, San Diego, USA) was used. To verify the normality of the data, the Shapiro-Wilk test was performed. Analysis of variance (ANOVA) for repeated measures, followed by the Bonferroni post hoc test, was used to the assessment of differences between groups at different moments (pre and post-fatigue protocol, and post-therapy). Finally, the Mann-Whitney test was performed to compare the energy value of R24 between the test days. Data are expressed as mean ± standard deviation or percentage values. The level of significance adopted was 5% (p < 0.05).

 

Results

 

The final study sample was composed of 14 young adults (22 ± 2 years), with good cardiorespiratory capacity (VO2MAX 44,1 ± 6,7 ml.kg-1.min-1) and a high percentage of fat (27. 8 ± 4.4%) for high-performance sports. Four athletes had their data excluded because they were in the process of recovery (injury not resulting from the research protocol). There was no difference in caloric intake between the two evaluation days (2,893 ± 802 versus 2,915 ± 746 kcal; p = 0.949).

 

Vertical jump test

 

Our data indicate a 10.9% reduction in the height of the CMJ between the PE and PF moments, approximately 8.2% between the PF and PT moments, and about 18.2% between the PE and PT moments (p < 0.05). Regarding active rest, a reduction of 2.2% in the height of the CMJ was observed between the PE and PF moments, an increase of 9.4% between the PF and PT moments, and a 7.1% increase between the PE moments and PT (p < 0.05). Figure 2 shows the performance of the CMJ in both interventions: immersion cryotherapy and active rest (control).

 

 

Figure 2 - Power of lower limbs after immersion cryotherapy and active rest; PE = pre-exercise; PF = post-fatigue protocol; PT = post-recovery protocol. *p<0.05 versus PE (cryotherapy protocol). †p<0.05 versus PE and PT (rest protocol). Bonferroni test

 

Isokinetic dynamometry

 

Our data indicate a 7.4% reduction in the isometric torque peak between PE and PF moments, an increase of approximately 4.0% between PF and PT moments, totaling a 3.7% reduction between PE and PT moments after immersion cryotherapy (p < 0.05). For the active rest, a reduction of 5.9% was observed in the peak of isometric torque between the PE and PF moments, a further reduction of 3.9% between the PF and PT moments, totaling a 9.6% lower performance between the PE and PT moments (p < 0.05). Figure 3 illustrates the performance of the isometric torque peak in both interventions: immersion cryotherapy and active rest (control).

 

 

 

Figure 3 - Isometric torque peak after immersion cryotherapy and active rest. PE: pre-exercise. PF: post-fatigue protocol. PT: post-recovery protocol. *p<0.01 versus PE (cryotherapy protocol). †p<0.01 versus PE (rest protocol). ††p<0.05 versus PF and PE (rest protocol). Bonferroni test

 

Discussion

 

Our objective was to verify if immersion cryotherapy could negatively impact lower limb isometric strength or power production of athletes submitted to a muscle fatigue protocol. Interestingly, our data indicated an antagonistic behavior of these variables. Immersed cryotherapy proved to be more efficient than active rest to recover isometric strength. However, for muscle power, active rest showed better results when compared to cryotherapy. Two factors can justify these findings: 1) the lower elastic capacity in cold environments, impairing muscle power; and 2) the unintended effect of the CMJ as a warm-up for dynamometry may have helped in the re-establishment of the participants' contractile capacity.

Indeed, Pritchard & Saliba [6] had argued that there is variability in the experimental design of studies that investigated the effect of cryotherapy, generating an interpretive bias, especially regarding the waiting period for testing. Kinzey et al. [21] state that it is necessary to wait 15 minutes after the application of cryotherapy to produce strength and / or muscle power to return to baseline levels. Although the waiting period for the present study was standardized and monitored (180 sec), randomization of the dependent variables was not performed, that is, the CMJ was performed before the strength test. This may partially justify the observed divergences. The unintended effect of jumping as a warm-up may have positively influenced the production of isometric strength after cryotherapy. Rhodes & Alexander [22] support this hypothesis by demonstrating a detrimental effect on test performance immediately after cryotherapy.

Similarly, Tassignon et al. [23] observed a reduction in the jump distance in participants who were exposed to the cryotherapy protocol at 10°C. This was not observed in the performance of the same participants when the technique was applied at a temperature of 18°C, suggesting that the treatment temperature is decisive for the desired response. Additionally, the authors observed a reduction in electromyographic activity during the isokinetic dynamometer test, which suggests lower recruitment of muscle fibers (lower speed of motor nerve conduction). Besides, Haupenthal et al. [24] observed that the application of ice reduced the proprioceptive capacity of the ankle dorsiflexor muscles, inhibiting isometric strength production. All these factors corroborate the result found in the present study. Nevertheless, the mechanism responsible for the performance impairments when the muscle is subjected to low temperatures is not yet fully understood. However, in 2019, Fuchs et al. [25] verified the effects of immersion baths with ice on skeletal muscle protein synthesis responses related to physical exercises and protein intake through food. Using stable isotopic markers and muscle biopsies, they evaluated a group of participants who did strength exercises on both legs for two weeks. After each exercise session, participants were exposed for 20 minutes with one leg in cold water (8°C) and the other in the water at neutral temperature (30°C). They reported a decrease in protein synthesis in the limb that received cryotherapy. According to the authors, immersion in cold water during recovery from strength exercises decreases the muscle's ability to absorb and / or direct dietary amino acids for synthesis and recovery of myofibrils.

The present study's methodology limits greater inferences for lacking deeper analyzes of physiological mechanisms and focusing on dynamic responses of muscle fatigue. We speculate that the application of cold may induce vasoconstriction, reducing the metabolic rate and, consequently, the demand for cellular oxygen, corroborating findings from Fuchs et al. [25]. These processes reduce cell death from secondary necrosis, decreasing damage to the contractile properties of the muscle. Interestingly, the lower performance in the isometric strength after active rest could be linked to the “muscle fatigue” state, since the jump test was performed before the dynamometer.

This study has some limitations such as not having randomized the evaluation process (jumping test versus dynamometer), having used only one temperature in the cryotherapy protocol, and evaluating a population of amateur athletes, limiting extrapolation of the results to other populations.

 

Conclusion

 

Based on the results found, it can be concluded that immersion cryotherapy has a negative impact on the production of explosive strength in the lower limbs, albeit it seems to assist in the recovery of the athletes' isometric strength. Thus, immersion cryotherapy needs to be applied with caution to accelerate recovery in short intervals, such as between combat rounds and/or game intervals, as it may not improve the athlete's performance.

 

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