Prof. Eloá Ferreira Yamada, PT., PhD.*

eloayamada@gmail.com

Prof. Renato Alves da Silva, Math, Mech. Eng., D.Sc.**

drenatoas@gmail.com

Arethuza Rodrigues Tedesco, PT.***

aretedesco@gmail.com

Jeferson Lima Barbosa Costa, PT.***

jefersonlbc@gmail.com

Mariana Schimith Pancieri, PT.***

maryschimith@hotmail.com

Samarone Nogueira Martins, PT.***

samaronenmartins@gmail.com

Vanessa Santana do Espírito Santo, PT.***

vanessaespiritosanto@gmail.com

*Physical therapist graduated from Universidade Estadual Paulista (FCT/UNESP)

Master in Biomedical Engineering from the Universidade do Vale do Paraíba (UNIVAP)

Doctor in Biochemistry from the Universidade Federal do Pampa (UNIPAMPA)

Adjunct Professor in Physiotherapy (Universidade Federal do Pampa (UNIPAMPA)

**Mathematician graduated from Universidade Estadual Paulista (FCT/UNESP)

Mechanical Engineering degree from Universidade do Norte do Paraná (UNOPAR)

Master in Science from the Instituto de Tecnológico da Aeronáutica (ITA)

Doctor in Science from the Instituto de Tecnológico da Aeronáutica (ITA)

Associate Professor at UNIPAMPA, Campus Uruguaiana

***Physical therapist graduated from Universidade Vila Velha (UVV)

(Brasil)

Reception: 02/28/2024 - Acceptance: 07/04/2024

1st Review: 04/27/2024 - 2nd Review: 06/30/2024

Accessible document. Law N° 26.653. WCAG 2.0

Suggested reference: Yamada, EF, Silva, RA, Tedesco, AR, Costa, JLB, Pancieri, MS, Martins, SN, y Santo, VSE (2024). Superficial Heat Therapy and Therapeutic Exercise in Individuals with Knee Osteoarthritis. Lecturas: Educación Física y Deportes, 29(316), 152-171. https://doi.org/10.46642/efd.v29i316.7491

 

Abstract

    Introduction: Knee Osteoarthritis is a major cause of pain and locomotor disability worldwide. Several physical therapy modalities have been recommended in reviewed clinical guidelines and systematic reviews, such as exercises, and electro and thermotherapy resources. Objective: This study evaluated the influence of the application of superficial heat therapy and/or therapeutic exercise on reducing pain and improving functional capacity in patients with knee osteoarthritis. Methods: 30 patients were divided into three groups (superficial heat, exercises, superficial heat plus exercises) and underwent 10 treatment sessions. Pain intensity was assessed using the visual analog scale; muscle flexibility with Wells’ bank test; strength gain with testing of one maximum repetition; walking time was analyzed with a walking test over a distance of 10 meters; and the Lequesne functional questionnaire was used to assess the functional activities of patients. Results: All treatments performed reduced knee pain. The exercise group showed an improvement in flexibility and quadriceps muscle strength. And the group that received superficial heat and therapeutic exercise showed better performance in time over a fixed distance covered. Conclusions: Therapeutic exercise and superficial thermotherapy performed in isolation showed beneficial effects in individuals with knee osteoarthritis. However, the therapeutic intervention carried out in combination showed better results in all parameters evaluated, suggesting that the clinical treatment can improve the quality of life of these individuals.

    Keywords: Knee. Osteoarthritis. Hyperthermia. Exercise therapy.

 

Resumo

    Introdução: A osteoartrite do joelho é uma das principais causas de dor e incapacidade locomotora em todo o mundo. Diversas modalidades fisioterapêuticas têm sido recomendadas em diretrizes clínicas revisadas e revisões sistemáticas, como exercícios e recursos de eletro e termoterapia. Objetivo: Este estudo avaliou a influência da aplicação de termoterapia superficial e/ou exercício terapêutico na redução da dor e na melhora da capacidade funcional em pacientes com osteoartrite de joelho. Métodos: 30 pacientes foram divididos em três grupos (calor superficial, exercícios, termoterapia superficial mais exercícios) e submetidos a 10 sessões de tratamento. A intensidade da dor foi avaliada por meio da escala visual analógica; flexibilidade muscular com teste de banco de Wells; ganho de força com teste de uma repetição máxima; o tempo de caminhada foi analisado com teste de caminhada de 10 metros; e o questionário funcional de Lequesne foi utilizado para avaliar as atividades funcionais. Resultados: Todos os tratamentos realizados reduziram a dor no joelho. O grupo de exercícios apresentou melhora na flexibilidade e na força muscular do quadríceps. E o grupo que recebeu termoterapia superficial e exercícios mostrou melhor desempenho no tempo numa distância percorrida fixa. Conclusões: O exercício terapêutico e a termoterapia superficial realizados isoladamente demonstraram efeitos benéficos em indivíduos com osteoartrite de joelho. Porém, a intervenção terapêutica realizada de forma combinada apresentou melhores resultados em todos os parâmetros avaliados, sugerindo que o tratamento clínico pode melhorar a qualidade de vida desses indivíduos.

    Unitermos: Joelho. Osteoartrite. Termoterapia. Exercício terapêutico.

 

Resumen

    Introducción: La osteoartritis de rodilla es una de las principales causas del dolor y discapacidad motriz. Varias modalidades de fisioterapia han sido recomendadas en las guías clínicas revisadas y revisiones sistemáticas, como ejercicios y electro y termoterapia. Objetivo: Se evaluó la influencia de la aplicación de termoterapia superficial y/o ejercicio terapéutico en la reducción del dolor y mejora de la capacidad funcional en pacientes con osteoartritis de rodilla. Métodos: 30 pacientes divididos en tres grupos (calor superficial, ejercicios, calor superficial más ejercicios) se sometieron a 10 sesiones de tratamiento. La intensidad del dolor se evaluó mediante la escala analógica visual; la flexibilidad muscular con el test de Wells; la ganancia de fuerza con la prueba de una repetición máxima; el tiempo de marcha se analizó con un test de marcha sobre una distancia de 10 metros; y el cuestionario funcional de Lequesne se utilizó para evaluar las actividades funcionales de pacientes. Resultados: Todos los tratamientos realizados redujeron el dolor de rodilla. El grupo de ejercicios mostró una mejora en la flexibilidad y la fuerza muscular de cuádriceps. Y el grupo que recibió calor superficial y ejercicio terapéutico mostró un mejor rendimiento en el tiempo sobre una distancia fija recorrida. Conclusiones: El ejercicio terapéutico y la termoterapia superficial realizados de forma aislada mostraron efectos beneficiosos en individuos con artrosis de rodilla. Sin embargo, la intervención terapéutica realizada en combinación mostró mejores resultados en todos los parámetros evaluados, sugiriendo que el tratamiento clínico puede mejorar la calidad de vida de estos individuos.

    Palabras clave: Rodilla. Artrosis. Hipertermia. Terapia con ejercicios.

 

Lecturas: Educación Física y Deportes, Vol. 29, Núm. 316, Sep. (2024)

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Introduction 

 

    Osteoarthritis (OA) of the knee is a significant cause of pain and locomotor disability globally (McAlindon et al., 2014; Bannuru et al., 2019; Long et al., 2022; Gibbs et al., 2023). This condition affects not only the joint lining but also cartilage, ligaments, and bone, characterized by the breakdown of cartilage, bone changes, deterioration of tendons and ligaments, and various degrees of inflammation of the synovium (Alshami, 2014). OA predominantly affects the middle-aged to elderly population, with almost 50% of people over 65 years old experiencing OA. As there are currently no treatments that delay or halt the progression of the disease, the prevalence of OA is expected to increase in an aging population (Carlos, Belli, & Alfredo, 2012; Davis et al., 2013). According to the Brazilian Society of Rheumatology (SBR), OA represents 30% to 40% of consultations in rheumatology outpatient clinics and accounts for 7.5% of all work absences. (SBR, 2022)

 

    Managing OA requires a multidisciplinary approach, including pharmacotherapy (such as oral or topical analgesic drugs e.g., NSAIDs, opioids, capsaicin), psychology, physical therapy, and occupational therapy (McAlindon et al., 2014; Bannuru et al., 2019; Gibbs et al., 2023). Treatment goals for OA patients are to control pain, address other symptoms, and improve functional capacity. Lower-risk and lower-cost interventions effective for chronic conditions like knee OA warrant further examination and attention when discussing treatment options or recommending a care plan (Denegar et al., 2010). Several physical therapy modalities, including land-based exercises (strengthening and aerobic exercises), are highly recommended by most guidelines. (McAlindon et al., 2014; Bannuru et al., 2019; Gibbs et al., 2023)

 

    Studies suggest that exercise therapy reduces pain and patient-reported disability in individuals with knee OA (Juhl et al., 2014). Land-based exercises have shown clinically relevant, short-term benefits for pain and physical function in OA management (McAlindon et al., 2014; Bannuru et al., 2019; Gibbs et al., 2023). Optimal exercise programs for knee OA should focus on improving aerobic capacity, quadriceps muscle strength, or lower extremity performance. (Juhl et al., 2014)

 

    Other treatment options for knee OA include periodic applications of superficial heat or cold, considered safe and cost-effective, either alone or combined with other treatments. Studies indicate that superficial heat alone or combined with other therapies effectively reduces OA symptoms (Denegar et al., 2010; Cameron, 2012; Shehata, & Fareed, 2013). The hydrocollator, a form of wet and superficial heat, delivers heat through units (bags) immersed in water and heated at temperatures between 45°C and 76°C. It promotes local vasodilation, accelerates cell metabolism, reduces sensory nerve thresholds, improves tissue elasticity (ligaments, capsule, and muscles), and reduces pain (Chiarello, Radl, and Driusso, 2005; Cameron, 2012; Namsawang, & Muanjai, 2020). This study evaluated the influence of the application of superficial heat therapy and/or therapeutic exercise on reducing pain and improving functional capacity in patients with knee OA.

 

Methods 

 

Sample 

 

    The study is characterized as a comparative, experimental clinical trial with a quantitative approach. Participants were verbally informed about the research and signed a consent form. This study was approved by the Ethics Committee of the University Center of Vila Velha, under number 228/2009. The research was characterized as a randomized clinical trial with a blinded evaluator.

 

Eligibility criteria 

 

    The research involved patients of both sexes, aged between 45 and 70 years, diagnosed with OA (in one or both knees) with a Kellgren-Lawrence grade of 2 or higher (grades range from 0 to 4 based on simple radiographic studies). Patients who had available time to participate in activities were included (10 sessions, 3 times a week, in the morning, each lasting 60 minutes). The exclusion criteria were: individuals whose medication dosage had been changed in the last month; those who underwent lower limb surgery in the last 6 months; those who received intra-articular injections within the last 3 months; individuals undergoing knee arthroplasty; those with artificial pacemakers; those with cognitive problems; and individuals with comorbidities such as venous thrombosis, heart disease, uncontrolled hypertension, rheumatoid arthritis and cancer.

 

Division of groups 

 

    The assessment and reassessment were conducted by a single-blind individual (without knowledge of the interventions), referred to as evaluator n. 1, who had been previously trained. Following the assessments, another evaluator (n. 2) assigned the patients to three distinct groups. Group allocation was performed randomly using the 'random function' tool in Microsoft Excel software: patients with values less than 0.3333 were assigned to group 1; patients with values greater than 0.3333 and less than 0.6666 were assigned to group 2; and patients with values from 0.6667 to 1.0000 were assigned to group 3. Evaluator n.2 then directed participants to therapists. Three therapists conducted the protocols for this research, all of whom had received prior training. Each therapist was responsible for applying the protocols in groups 1, 2, and 3, respectively.

 

    The patients with knee OA were randomly divided into three groups:

• Group 1 (n=10): Superficial heat. The treatment consisted of applying hydrocollator hot packs. The bags were submerged in water in a stainless steel vessel at a temperature of approximately 76 °C. They were subsequently applied to the OA knee (patient in supine position), which was previously dried with six layers of towels. The skin knee temperature was maintained around 40°C to 45°C and applied for 20 minutes (Chiarello, Radl, & Driusso, 2005; Cameron, 2012; Namsawang, & Muanjai, 2020; Artuç et al., 2023) (Figure 1A).

• Group 2 (n=10): Therapeutic exercise. Passive stretching of the lower limbs was initially performed on individuals. The patient remained in the supine position, where the therapist performed full knee extension (respecting the physical limits of each patient) and dorsiflexion of the foot bilaterally for ischiotibial and sural triceps stretching, lasting 30 seconds. Then, the individual assumed a prone position, and the therapist performed total knee bending (up to the limit of each individual) for quadriceps stretching, also lasting 30 seconds, bilaterally. The exercises consisted of using the ergometer bike (20 minutes) and 8 repetitions of knee extension in 3 sets on the extension table (with 60% of the value obtained for each knee in the one maximal repetition (1MR) test) for quadriceps fortification. All stretches were repeated at the end of the exercises (Yamada et al., 2019; Holden et al., 2021) (Figure 1B and 1C).

• Group 3 (n=10): Superficial heat and therapeutic exercise. Individuals with OA underwent a combination of both techniques. The use of superficial heat was followed by therapeutic exercise, as previously described. The exercises were performed bilaterally, and the application of superficial heat was performed only on the affected knee (Figure 1).

Figure 1. (A) shows the hydrocollator hot pack. (B) and (C) represent parts of therapeutic exercises

Source: Authors' personal archives

 

Procedures 

 

    The evaluation of the participants was performed by a previously trained physiotherapist who was blind to the study, and it lasted for 60 minutes. All participants were assessed individually, and each testing session followed the same sequence.

 

Assessment of Pain 

 

    To assess pain, the visual analogue scale (VAS) was used, with 0 indicating no pain and 10 representing maximum pain. The scale was performed for each OA knee (right or left or both sites), at the beginning and the end of each treatment. (Tonella, Araújo, & Silva, 2006)

 

Sit and Reach with Well’s Bank Test 

 

    In order to analyze posterior muscle flexibility, the sit and reach test was performed with the Wells Bank. In this test, the patient was positioned sitting on a mat with their feet in full contact with the front edge of the seat, with knee extension and hip flexion. After accurate positioning, individuals were instructed to move the bank's scale to the maximum they could, performing a body flexion. The value obtained for each trial was expressed in centimeters (cm) and was immediately recorded by the evaluator. Three attempts were made, and only the highest value was considered in the data analysis. (Bertolla et al., 2007; Lutut, 2019)

 

Muscle Strength Test 

 

    The muscle strength test used was the one maximal repetition (1MR), which determines the maximum load that the individual can lift for one repetition and then works with 60% of that maximum load (1MR test). The test was performed on the leg extension chair, with the subject seated comfortably and the column adjusted to the patient's height. After performing a full knee extension without compensating the column and pelvis, starting with 1 kg and gradually increasing until the patient completed all movements correctly with the highest weight possible. This test was performed bilaterally for the quadriceps muscle group. (Mazini Filho et al., 2010)

 

Walking Test 

 

    The patients were instructed to walk naturally (at a comfortable pace) over a distance of 10 meters. One or two steps for walking acceleration and deceleration were allowed between the 8 central meters, a process for which reliability has been demonstrated. Three replicates were performed, timing the time required to complete the distance traveled (McCarthy et al., 2004). For data analysis, the average value of the times obtained was used.

 

Lequesne Functional Questionnaire (LFQ) 

 

    This index consists of eleven questions, six of which are about pain and discomfort, one about walking ability, and four on activities of daily living. The scores range from 0 to 24, indicating no impairment to very severe impairment, respectively. This questionnaire is recommended by the World Health Organization (WHO) for evaluating OA, which influenced its selection for use in this study. (Marx et al., 2006)

 

Statistical analysis 

 

    The sample calculation was based on the number of inhabitants of the municipality over the age of 60. For the sample size calculation, a confidence level of 90% and a maximum error of 10% were set, resulting in a total of 68 participants.

 

    The simple size, n, was determined by the following expression:

 

    Where E  the margin of error is, p is proportional of individuals with OA in the elderly population, Z is the critical value from the confidence level table. For an assumed proportion of OA persons,

 

    thus:

 

 

    The Kolmogorov-Smirnov test confirmed the normality of the data. The statistical analysis utilized the paired Student t-test to compare before and after values within each group, with significance set at p<0.05, very significance for p<0.01, and highly significant for p<0.001. For intergroup analysis, ANOVA with Tukey post-test was employed to compare the means of each group after treatment and to evaluate differences in values.

 

    The effect sizes of superficial heat, therapeutic exercises, and the combination of superficial heat and therapeutic exercises on pain, muscle flexibility, strength, walking distance, and quality of life were estimated using Hedge’s g. Effect sizes were interpreted as negligible (0 ≤ g < 0.2), small (0.2 ≤ g < 0.5), medium (0.5 ≤ g < 0.8), or large (g ≥ 0.8)

 

Results 

 

Characteristics of individuals 

 

    The participants were selected using convenience sampling method. Seventy individuals were evaluated, of whom 30 did not meet the inclusion criteria for this study. Additionally, 10 individuals discontinued treatment (9 due to personal reasons), and one person passed away before completing the treatment. Therefore, only 30 individuals successfully completed all treatment sessions (Figure 2). The characteristics of all individuals are summarized in Table 1.

 

Source: Research data

 

Groups	Age	OA knee (%)	Sex (%)
Group 1 (n=10)	65,30 ± 7,42	90% Bilateral 10% Left	100% Female
Group 2 (n=10)	63,20 ± 6,46	50% Bilateral 40% Right 10% Left	80% Female 20% Male
Group 3 (n=10)	64,10 ± 6,40	100% Bilateral	90% Female 10% Male

Source: Research data

 

Reduction in knee pain 

 

    Participants reported their pain levels using the visual analogue scale (VAS) before and after ten treatments of each therapy. As illustrated in Figure 2 (A), a reduction in pain was observed in all experimental groups. In the superficial heat group (G1), subjects initially reported a mean VAS pain level of 5.75 (± 0.47), which decreased to 0.90 (± 0.30) after treatment. In the therapeutic exercise group (G2), the mean pain intensity was 4.40 (± 0.45), and after treatment, it reduced to 1.25 (± 0.32). In the superficial heat plus therapeutic exercise group (G3), the mean pain level was 6.10 (± 0.46), and subsequently, it was 0.95 (± 0.38). All treatments significantly (p < 0.001) reduced the VAS scores for ipsilateral OA knee (Figure 3A), indicating a reduction in knee pain levels. There were no statistical differences observed between groups after treatment. The Hedge's g effect sizes for pain were 2.64, 1.72, and 2.60 for G1, G2, and G3, respectively.

 

Therapeutic exercise alone or combined with superficial heat increased the flexibility of individuals with knee OA 

 

    The influence of treatments (superficial heat, therapeutic exercise, or the combination of both therapies) on muscle flexibility was verified through the "sit and reach test" using Well's Bank. Prior to treatment, Group 1 (G1) had an average of 28.20 (± 2.35) cm, which increased to 29.51 (± 2.47) cm after the procedures. Group 2 (G2) started with an average of 22.32 (± 2.65) cm, which improved to 24.41 (± 2.38) cm post-treatment. In Group 3 (G3), the initial average was 25.55 (± 2.78) cm, increasing to 29.22 (± 2.34) cm. Therapeutic exercise significantly increased body flexibility (p < 0.01) (Figure 2B). Similar effects were observed in the superficial heat plus therapeutic exercise group (p < 0.01), showing an increase in the reach distance on the Wells' Bank (Figure 3B). No significant effects of superficial heat treatment alone were observed on body flexibility. There were no statistical differences among groups after treatments. The Hedge's g effect sizes for flexibility were 0.16, 0.25, and 0.43 for G1, G2, and G3, respectively.

 

Therapeutic exercise alone or combined with superficial heat increased the quadriceps muscle strength 

 

    It was tested whether superficial heat or/and therapeutic exercise had any effect on muscle strength by measuring the one maximal repetition (1MR) of the right and left knee. The one maximal repetition (1MR) results showed significantly greater muscle strength in groups treated with therapeutic exercise. The initial mean 1MR for G1 was 1.35 ± 0.29, which increased to 1.70 ± 0.20 by the end. In G2, the initial mean was 2.05 ± 0.35, and after treatment, it was 3.65 ± 0.42. In G3, the initial mean was 2.23 ± 0.26, and after the procedures, it was 3.95 ± 0.36, as depicted in Figure 3C. The participant groups with therapeutic exercise or therapeutic exercise plus superficial heat significantly increased muscle strength (p < 0.0001 in both groups). When comparing groups after treatment, G2 and G3 showed no statistical differences. Therefore, therapeutic exercise alone or combined with superficial heat was able to increase muscle strength in individuals with knee OA. The Hedge's g effect sizes of the pain were 0.30, 0.88 and 1.17 for G1, G2 and G3, respectively.

 

Therapeutic exercise combined with superficial heat increased the distance walk 

 

    To examine whether individuals could walk faster over a 10 meters distance after our treatments, the walk test was utilized. It was observed that superficial heat was not able to make the participants walk faster than before the therapy was applied to the OA knee (mean before 9.98 seconds ± 1.14, mean after 7.87 ± 0.48 seconds). Similarly, therapeutic exercise alone (G2) also did not decrease the time in the walk test (mean before 7.58 ± 0.65 s, mean after 6.37 ± 0.28 s). Interestingly, only group 3 (therapeutic exercise plus superficial heat) reduced the time individuals took to complete the test (mean before 8.64 ± 0.55 s, mean after 7.47 ± 0.52 s) (Figure 3D). No statistical differences were observed among the experimental groups. The Hedge's g effect sizes of the pain were 0.73, 0.73 and 0.66 for G1, G2 and G3, respectively.

 

Source: Research data

 

Therapeutic exercise, superficial heat or both therapies together improved quality of life in individuals with knee OA 

 

    OA patients showed a reduction in functional capacity after being treated with superficial heat, therapeutic exercise, or both therapies combined. The LFQ includes questions about pain and discomfort, walking distance, and activities of daily living. In the initial evaluation (before treatments), the mean in G1 was 9.55 (± 0.85), and in the final evaluation, it was 3.20 (± 0.85). In G2, the initial mean was 8.25 (± 0.73), and at the end, it was 2.85 (± 0.64). In G3, the initial average was 11.15 (± 1.30), and the final average was 2.25 (± 0.71).

 

    All treatments in our three experimental groups significantly (p < 0.001) decreased the LFQ score (Figure 4). There was no statistically significant difference between our three experimental groups in LFQ after the procedures. The Hedge's g effect sizes of the pain were 2.26, 2.37 and 2.57 for G1, G2 and G3, respectively.

 

Source: Research data

 

Discussion 

 

    The ineffective management of pain and the increasing rates of disability associated with OA demand a change in our treatment paradigm, as new therapies or protocols must be developed. (Dimitroulas et al., 2014)

 

    The present study demonstrates that superficial heat and therapeutic exercise could be used alone or combined with superficial heat to relieve pain, increase flexibility, and improve muscle strength with the aim of promoting a better quality of life for individuals with knee OA. Previous studies show that the common practice of superficial heat and cold for pain relief is limited, but there is moderate evidence that heat wrap therapy provides a small short-term reduction in pain and disability in a population with low back pain, and that the addition of exercise further reduces pain and improves function (French et al., 2006). A study comparing the use of a thermal rice bag and the hydrocollator found reduced pain and increased functional independence in individuals with knee OA (Namsawang, & Muanjai, 2020). Although both treatments, used alone, have reduced knee OA pain in this work, it was not able to observe a cumulative effect in reducing pain when combined the two therapies. Therapeutic exercise combined with superficial heat decreased the pain of the participants as well as the techniques used alone (superficial heat or therapeutic exercise).Thermotherapy increases blood flow in the soft tissues of the medial and lateral compartments of the knee, promotes the release of growth factors and cytokines that favor the repair process, and increases the supply of oxygen, which in turn promotes the reduction of local pain and inflammation. (Rodríguez-Grande et al., 2017)

 

    A deeper understanding of the multiple mechanisms of OA pain has led to the use of centrally acting medicines that may benefit in alleviating osteoarthritic pain (Dimitroulas et al., 2014). Pain pathways are different in OA disease, and some authors reported the targeting of inflammation in bone, nerves, and central pain (Wenham, & Conaghan, 2013). Both clinical and experimental studies have provided evidence for the sensitization of pain pathways during OA, involving pronounced changes in joint nociceptors and changes in the nociceptive process in the spinal cord, brainstem, and thalamocortical system (Schaible, 2012; Johnson et al., 2022). Additionally, a growing amount of evidence suggests that the pain in OA has a neuropathic component in some patients (Dimitroulas et al., 2014). Artuç et al. (2023) found that the use of a hydrocollator reduced pain sensitivity in patients with knee OA, in addition to obtaining better scores on the Western Ontario and McMaster Universities Osteoarthritis Index, Timed Up and Go Test, Pain Catastrophizing Scale, Beck Depression Inventory, and Tampa Scale of Kinesiophobia. Johnson et al. (2022) state that using therapies involving heating or cooling the skin to relieve pain provides attenuation of intensity and quality, and reduces the perceived bodily threat. The results of this work seem to indicate that superficial heat and therapeutic exercise could act on the central aspect of pain, but mainly on peripheral pathways, reducing central sensitization and thus pain perception by individuals affected with OA.

 

    In the study, it is shown that only individuals with OA knee treated with therapeutic exercise increased flexibility and muscular strength. Contributing to the reduction of pain, stretching reduces myofascial retractions, decompressing joints, ensuring cartilage nutrition, and preventing joint wear. Muscle stretching increases muscle flexibility and improves periarticular tissues, ensuring amplitudes of joint movements compatible with activities of daily living (Chiarello, Radl, & Driusso, 2005; Starkey, 2013). Furthermore, as pain intensity decreases, input from Paccini's mechanoreceptors and free nerve endings decreases, inhibition of the Ib pathway decreases, which would facilitate the activation of MNα and consequently the recruitment of muscle fibers, thus increasing strength. (Rodríguez-Grande et al., 2017)

 

    Patients with knee OA have a reduced ability to contract quadriceps (reduced strength), which may be due to muscle atrophy and muscle inhibition, which is the inability to fully and voluntarily activate the muscle (Alnahdi, Zeni, & Snyder-Mackler, 2012). Some authors show that adults with end-stage hip OA were 10-38% weaker in their arthritic lower extremity, performed 28-50% poorer on functional tests, and were less physically active than healthy adults (Judd et al., 2014). In another study, authors found that the efficiency for maximum muscle strengthening is possible when combined with strength, flexibility, and functional exercises, which was confirmed in this study (Bennell, Dobson, & Hinman, 2014). In fact, various types of exercise are recommended for the management of knee OA in all clinical guidelines irrespective of disease severity, pain levels, and functional status because exercise improves pain and function in the short term. (Bennell, Dobson, & Hinman, 2014)

 

    Quadriceps muscle weakness may contribute to worsening knee pain. Yet, pain inhibits reflex muscular activity, causing atrophy and muscle weakness. The painful process could cause muscular weakness. Exercise may reduce pain and knee function, providing indirect evidence for a relationship between quadriceps muscle strength and knee pain (Glass et al., 2013). Muscle training reduces pain symptoms being held in cyclical and originally with light loads, stimulating the synthesis of cartilage matrix, accelerating the process of remodeling the cartilage. Exercise increases the joint space, improving lubrication and reducing joint pain (Chiarello, Radl, & Driusso, 2005). In this study, it was demonstrated that therapeutic exercise alone or combined with superficial heat was able to increase flexibility and the muscle strength of the quadriceps muscle and reduce knee pain in individuals with OA.

 

    Therapeutic exercises have been recommended because they improve aerobic capacity, muscle strength, endurance, flexibility, and help the person achieve specific functional goals, such as increasing walking capacity. In addition, combined programs on land or in water, aimed at developing variable maximum strength and aerobic fitness in the same session, seem to be more effective at improving strength and aerobic fitness. (Sbardelotto et al., 2019)

 

    Stationary cycling exercise was able to relieve pain and improve function in individuals with knee osteoarthritis, compared to wait-and-see and education alone, but it was not as clinically effective for improving stiffness, daily activity, and quality of life (Luan et al., 2021). In the present study, the stationary bike exercise for a period of 20 minutes was used, and similarly here, individuals who exercised were associated.

 

    It is not known how superficial heat could add benefits in this group; however, the influence of heat on muscle strength and gain can be explained by sensory stimulation of A-beta fibers (large diameter), inhibiting the transmission of painful stimuli in the spinal cord. The application of heat reduces stimuli of muscle spindles and the amount of metabolites, reducing joint stiffness and breaking the pain-spasm-pain cycle. Therefore, the improvement in recruitment of muscle fibers optimizes muscle contraction, thereby increasing strength. (Cameron, 2012; Starkey, 2013; Prentice, 2014)

 

    Karadağ et al. (2019) studied the effect of applying superficial local heat and a home exercise program in patients with bilateral knee osteoarthritis and observed that patients showed a decrease in pain and joint stiffness, as well as improved function.

 

    The application of local heat has been widely used as a non-pharmacological treatment modality for managing knee OA (Shen et al., 2021). The current study demonstrated the effectiveness of applying heat combined with performing therapeutic exercises for managing pain as well as overcoming functional disabilities, providing improvements in the quality of life of these individuals.

 

    The small number of individuals per experimental group can be considered a limitation of the study, as well as the utilization of only three experimental groups. Further investigation could explore the use of superficial thermotherapy and/or the combination of other exercises to alleviate the signs and symptoms of knee OA and enhance the quality of life of individuals in greater detail.

 

Conclusion 

 

    Therapeutic exercise and superficial thermotherapy performed individually demonstrated beneficial effects in individuals with knee OA. However, the combination of therapeutic interventions showed even better results in reducing walking time over the same distance, suggesting that this clinical treatment can improve the quality of life for these individuals.

 

References 

 

Alnahdi, A.H., Zeni, J.A., & Snyder-Mackler, L. (2012). Muscle impairments in patients with knee osteoarthritis. Sports Health, 4(4), 284-292. https://doi.org/10.1177/1941738112445726

 

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Lecturas: Educación Física y Deportes, Vol. 29, Núm. 316, Sep. (2024)