Local Heat Therapy Research Articles

Extending localized passive heat therapy benefits for individuals with exercise intolerance.

Extending localized passive heat therapy benefits for individuals with exercise intolerance.

Sixweeks of localized passive heat therapy elicits some exercise-like improvements in resistance artery function.

The purpose of this study was to examine the effects of 6weeks of localized, muscle-focused (quadriceps femoris) passive heat therapy (PHT) on resistance artery function, exercise haemodynamics and exercise performance relative to knee extension (KE) exercise training (EX). We randomized 34healthy adults (ages 18-36; n=17 female, 17male) to receive either PHT or sham heating sessions (120min, 3days/week), or EX (40min, 3days/week) over 6weeks. Blood flow was assessed with Doppler ultrasound of the femoral artery during both passive leg movement (PLM) and a KE graded exercise test. Muscle biopsies were taken from the vastus lateralis at baseline and after 6weeks. Peak blood flow during PLM increased to the same extent in both the EX (∼10.5% increase, P=0.009) and PHT groups (∼8.5% increase, P=0.044). Peak flow during knee extension exercise increased in EX (∼19%, P=0.005), but did not change in PHT (P=0.523) and decreased in SHAM (∼7%, P=0.020). Peak vascular conductance during KE increased by ∼25% in EX (P=0.030) and PHT (P=0.012). KE peak power increased in EX by ∼27% (P=0.001) but did not significantly change in PHT and SHAM groups. Expression of endothelial nitric oxide synthase increased significantly in both EX (P=0.028) and PHT (P=0.0095), but only EX resulted in increased angiogenesis. In conclusion, 6weeks of localized PHT improved resistance artery function at rest and during exercise to the same extent as exercise training but did not yield significant improvements in performance. KEY POINTS: Many for whom exercise would be most beneficial are either unable to exercise or have a very low exercise tolerance. In these cases, an alternative treatment to combat declines in resistance artery function is needed. We tested the hypothesis that passive heat therapy (PHT) would increase resistance artery function, improve exercise haemodynamics and enhance exercise performance compared to a sham treatment, but less than aerobic exercise training. This report shows that 6weeks of localized PHT improved resistance artery function at rest and during exercise to the same extent as exercise training but did not improve exercise performance. Additionally, muscle biopsy analyses revealed that endothelial nitric oxide synthase expression increased in both PHT and exercise training groups, but only exercise resulted in increased angiogenesis. Our data demonstrate the efficacy of applying passive heat as an alternative treatment to improve resistance artery function for those unable to receive the benefits of regular exercise.

The effect of abdominal heat therapy on constipation

Background: Constipation is one of the most common complications of the digestive system and has a significant impact on people's health and quality of life. One of the proposed non-drug interventions is the use of heat therapy. This study aimed to determine the effect of abdominal heat therapy on constipation. Aims: To identify if the use of heat therapy reduces constipation in elderly people admitted to the general internal medicine department. Methods: This study employs a triple-blind clinical trial design. A total of 92 elderly patients admitted to the internal medicine department of Sinai Hospital in Arak City in 2023 were randomly assigned to either a control or intervention group. Patients in the intervention group received local heat therapy using a standard hot water bottle with a temperature of 50°C applied to the abdomen. The control group received a hot water bottle at a temperature of 25°C. Data collection tools included the Bristol Stool Form Scale and a demographic data sheet. Analysis was conducted using SPSS 16. Results: The results showed that stool consistency was similar between the interventional and control groups before applying the hot water bag to the abdomen. A significant difference was observed on the first day (P=0.001) and the second day (P=0.005). There was a significant difference in stool consistency before the intervention, on day 1 and day 2 (P<0.001), but most people in the control group had no defecation. Conclusions: Local heat therapy improves bowel function and reduces constipation during defecation in the elderly, and its use is suggested at the same time as complementary studies.

Skeletal muscle oxidative adaptations following localized heat therapy

Repeated heat treatment has been shown to induce oxidative adaptations in cell cultures and rodents, but similar work within human models is scarce. This study investigated the effects of 6 weeks of localized heat therapy on near-infrared spectroscopy-(NIRS) derived indices of muscle oxidative and microvascular function. Twelve physically active participants (8 males and 4 females, age: 34.9 ± 5.9 years, stature: 175 ± 7 cm, body mass: 76.7 ± 13.3 kg) undertook a 6-week intervention, where adhesive heat pads were applied for 8 h/day, 5 days/week, on one calf of each participant, while the contralateral leg acted as control. Prior to and following the intervention, the microvascular function was assessed using NIRS-based methods, where 5 min of popliteal artery occlusion was applied, and the reperfusion (i.e., re-saturation rate, re-saturation amplitude, and hyperemic response) was monitored for 2 min upon release. Participants also performed a 1-min isometric contraction of the plantar flexors (30% maximal voluntary contraction), following which a further 2 min interval was undertaken for the assessment of recovery kinetics. A 20-min time interval was allowed before the assessment protocol was repeated on the contralateral leg. Repeated localized heating of the gastrocnemius did not influence any of the NIRS-derive indices of microvascular or oxidative function (p > 0.05) following 6 weeks of treatment. Our findings indicate that localized heating via the use of adhesive heat pads may not be a potent stimulus for muscle adaptations in physically active humans.

Do Heat And Exercise Training Elicit Similar Adaptations In Vascular Function During Rest And Exercise?

Heat, the major byproduct of exercise, may mediate many of the vascular adaptations that come from exercise, making heat therapy a potential alternative to exercise in situations where exercise is not possible. PURPOSE: Compare the effects of 6 weeks of exercise or heat training on resistance artery function at rest and during exercise. METHODS: Thirty-five (18 female) untrained subjects completed either 6-weeks of high-intensity, single-leg, knee-extension exercise (40 mins, 3x per week, n = 11), localized heat training (pulsed short-wave diathermy for 120 minutes, 3x per week n = 13), or a sham heat training protocol (120 minutes, 3x per week, n = 11). Vascular function was measured before and after the training. Specifically, resistance artery function was assessed at rest with the passive leg movement induced hyperemia (PLM). Leg blood flow and vascular conductance were also measured with Doppler Ultrasound and finometry during submaximal, steady-state knee extension (KE) exercise at 10 W and during a maximal graded KE exercise test. RESULTS: Resistance artery function, assessed by peak blood flow during PLM, increased in the exercise (~10.5% increase, P = 0.009) and heating groups (~8.5% increase, P = 0.044) to the same extent (P = 0.625); but tended to decrease in the sham group (P = 0.087). While blood flow during submaximal KE (10 W) did not change in any group, vascular conductance at 10 W tended to increase in the exercise group (19%, P = 0.056) and the heat group (16%, P = 0.036), but did not change in the sham group (P = 0.915). Likewise, maximum vascular conductance during KE significantly increased by ~25% in the exercise (P = 0.030) and heat (P = 0.012) groups but did not change in the sham group (P = 0.699). Importantly, the magnitude of change in resistance artery function, assessed by PLM, was related to the change in maximal vascular conductance (r = 0.50, P = 0.006). Maximum power achieved during KE only increased in the exercise group (~27%, P = 0.001). CONCLUSIONS: Localized heat therapy improved resistance artery function and exercise vascular conductance to the same extent as exercise training but did not yield significant improvements in exercise performance. Thus, heat therapy may be used to achieve many of the vascular benefits of exercise.

Localized Heat Therapy Improves Mitochondrial Respiratory Capacity but Not Fatty Acid Oxidation.

AIM: Mild heat stress can improve mitochondrial respiratory capacity in skeletal muscle. However, long-term heat interventions are scarce, and the effects of heat therapy need to be understood in the context of the adaptations which follow the more complex combination of stimuli from exercise training. The purpose of this work was to compare the effects of 6 weeks of localized heat therapy on human skeletal muscle mitochondria to single-leg interval training. METHODS: Thirty-five subjects were assigned to receive sham therapy, short-wave diathermy heat therapy, or single-leg interval exercise training, localized to the quadriceps muscles of the right leg. All interventions took place 3 times per week. Muscle biopsies were performed at baseline, and after 3 and 6 weeks of intervention. Mitochondrial respiratory capacity was assessed on permeabilized muscle fibers via high-resolution respirometry. RESULTS: The primary finding of this work was that heat therapy and exercise training significantly improved mitochondrial respiratory capacity by 24.8 ± 6.2% and 27.9 ± 8.7%, respectively (p < 0.05). Fatty acid oxidation and citrate synthase activity were also increased following exercise training by 29.5 ± 6.8% and 19.0 ± 7.4%, respectively (p < 0.05). However, contrary to our hypothesis, heat therapy did not increase fatty acid oxidation or citrate synthase activity. CONCLUSION: Six weeks of muscle-localized heat therapy significantly improves mitochondrial respiratory capacity, comparable to exercise training. However, unlike exercise, heat does not improve fatty acid oxidation capacity.

Localized Heat Therapy Improves Mitochondrial Respiratory Capacity but Not Fat Oxidation in Human Skeletal Muscle

Exercise training (EX) imposes stress on skeletal muscle, resulting in improved mitochondrial respiratory capacity and fat oxidation. Heat, which is one of the stresses of exercise, has been previously shown to increase mitochondrial respiration in human skeletal muscle. Still, it is unknown how the effects of localized heat therapy (HEAT) compare to the effects of EX, or if HEAT improves fat oxidation capacity. Therefore, the objective of this study was to determine the extent to which 6 weeks of HEAT improve mitochondrial function compared to EX. We hypothesized that HEAT would increase mitochondrial respiratory capacity, fatty acid oxidation and citrate synthase (CS) activity, but to a lesser extent than EX. Subjects were randomized into three groups: HEAT (n=11), EX (n=8), and a sham control group (CON, n=12). Subjects in the HEAT group were exposed to 2 hrs/day, 3 days/wk of short‐wave diathermy, which raised internal muscle temperature by 3.2 ± 0.33° C, while CON subjects experienced no change in muscle temperature during sham diathermy sessions. EX consisted of single‐leg extension exercise on a modified cycle ergometer for 45 min/day, 3 days/week, and resulted in a 1.8 ± 0.42° C increase in muscle temperature. Muscle biopsies were performed at baseline, and after 3 and 6 weeks of intervention. Small muscle fiber bundles (2‐4 mg wet wt.) were permeabilized, and mitochondrial respiration was assessed using high‐resolution respirometry (Oroboros O2k, Innsbruck, Austria). CS and 3‐hydroxyacyl‐CoA dehydrogenase (HAD) activity assays were performed in duplicate on supernatant from homogenized muscle samples. At 6 weeks, EX resulted in 27.9 ± 8.7% and 33.2 ± 11.7% increases in maximal coupled and uncoupled respiration, respectively, which were significantly different from baseline (p&lt;0.05). At 6 weeks, HEAT resulted in 24.8 ± 6.2% and 24.5 ± 6.2% increases in maximal coupled and uncoupled respiration, respectively, which were significantly different from baseline (p&lt;0.05), but not different from EX. Fatty acid oxidation was improved only in EX subjects after 6 weeks (29.5 ± 6.8%), compared to baseline (p&lt;0.05), with no change in HEAT or CON subjects. CS activity increased in EX subjects (25.9 ± 10.5 µmol·min‐1·mg protein‐1 or 19.0 ± 7.4%) compared to all others (p&lt;0.05), but no changes were observed in HEAT or CON subjects. Furthermore, no change in HAD activity occurred in any group. These results suggest that HEAT improves mitochondrial respiratory capacity to a similar extent as EX but does not result in other EX‐induced adaptations like increased fat oxidation and CS activity. Still, HEAT‐induced improvements in respiratory capacity may have therapeutic potential in the context of skeletal muscle disease or disuse, and further investigation is warranted.

Recurrent Botryomycosis and Management Strategy with a Follow-up of Four Years: A Case Report

Cervicofacial botryomycosis is a chronic, granulomatous suppurative infection with varied presentations in the head and neck region. Since the discovery of this entity, treatment has been elusive without evidence of complete resolution of the lesion with a long period of follow-up. Here the authors report a case of cervicofacial botryomycosis with oral manifestations in a 37-year-old male patient with a history of trauma, for whom the authors devised a treatment plan tailored to the patient's microbiological profile after culture and sensitivity testing in addition to systemic and local antibiotic therapy and heat therapy which showed drastic regression of the lesion and an improved mouth opening. The patient has been under follow-up for the past four years without signs of recurrence. Botryomycosis is an aggressive lesion where a surgery-only approach is usually futile and requires further intervention due to recurrences. The present experience suggests surgical debridement along with antibiotic and local heat therapy to be effective in managing this usually recurring lesion.

A novel therapy for granulomatous lobular mastitis: Local heat therapy.

Granulomatous lobular mastitis (GLM) is a chronic inflammatory breast condition that is characterized by granulomatous inflammation. GLM remains a refractory disease due to its failure to respond to routine anti-inflammatory therapies and its high recurrence rate. Thus, the present study aimed to investigate the application of local heat therapy in GLM as a potential therapeutic strategy. The results revealed that the application of local heat therapy was associated with a shortened remission time for GLM, while the remission and recurrence rates were similar to those of existing therapies. The median first remission time following local heat therapy was significantly decreased compared with that following corticosteroid therapy (5.30 months vs. 11.27 months; P<0.05). The remission rates were not significantly different between the local heat therapy (76.9%), extensive excision (90.4%) and the corticosteroid therapy (85.7%) groups (P>0.05). In addition, the recurrence rates were not statistically different between the groups (local heat therapy, 8.3%; extensive excision, 10%; and corticosteroid therapy, 10%; P>0.05). The local heat therapy showed mild adverse effects and shortened healing times compared to the other therapies; however, further confirmation is required.

The Effect of Local Heat Therapy versus Cold Rub Gel on Pain and Joint Functions in Patients with Knee Osteoarthritis.

This study compared the effect of local heat therapy versus cold rub gel on pain and joint function in patients with knee osteoarthritis. One hundred seventeen patients with knee osteoarthritis were randomly assigned to cold rub gel, local heat therapy, and control group. Data were collected by knee injury and osteoarthritis outcome score at a week prior to the interventions and on weeks of 1, 2, 3, and 4 of the interventions. A significant difference was found between the three groups in terms of pain severity (p = .001), joint symptoms (p = .001), ADL function (p = .001), Sport and Recreation function (p = .001), except Knee related QOL (p = .3). Cold rub gel and heat therapy were both effective in improving pain and joint function in patients with knee osteoarthritis.

Neither Peristaltic Pulse Dynamic Compressions nor Heat Therapy Accelerate Glycogen Resynthesis after Intermittent Running.

To investigate the effects of a single session of either peristaltic pulse dynamic leg compressions (PPDC) or local heat therapy (HT) after prolonged intermittent shuttle running on skeletal muscle glycogen content, muscle function, and the expression of factors involved in skeletal muscle remodeling. Twenty-six trained individuals were randomly allocated to either a PPDC (n = 13) or a HT (n = 13) group. After completing a 90-min session of intermittent shuttle running, participants consumed 0.3 g·kg-1 protein plus 1.0 g·kg-1 carbohydrate and received either PPDC or HT for 60 min in one randomly selected leg, while the opposite leg served as control. Muscle biopsies from both legs were obtained before and after exposure to the treatments. Muscle function and soreness were also evaluated before, immediately after, and 24 h after the exercise bout. The changes in glycogen content were similar (P > 0.05) between the thigh exposed to PPDC and the control thigh ~90 min (Control: 14.9 ± 34.3 vs PPDC: 29.6 ± 34 mmol·kg-1 wet wt) and ~210 min (Control: 45.8 ± 40.7 vs PPDC: 52 ± 25.3 mmol·kg-1 wet wt) after the treatment. There were also no differences in the change in glycogen content between thighs ~90 min (Control: 35.9 ± 26.1 vs HT: 38.7 ± 21.3 mmol·kg-1 wet wt) and ~210 min (Control: 61.4 ± 50.6 vs HT: 63.4 ± 17.5 mmol·kg-1 wet wt) after local HT. The changes in peak torque and fatigue resistance of the knee extensors, muscle soreness, and the mRNA expression and protein abundance of select factors were also similar (P > 0.05) in both thighs, irrespective of the treatment. A single 1-h session of either PPDC or local HT does not accelerate glycogen resynthesis and the recovery of muscle function after prolonged intermittent shuttle running.

The effect of local heat therapy on fatigue among patients with chronic obstructive pulmonary disease: A randomized controlled clinical trial

Background &amp; Aim: Fatigue is one of the most prevalent symptoms among people with chronic obstructive pulmonary disease (COPD). Heat therapy is considered as one of the proposed methods to relieve the symptoms in these patients. Therefore, the aim of this study was to determine the effect of local heat therapy on fatigue among patients with COPD. Methods &amp; Materials: This randomized controlled clinical trial study was conducted on 46 patients with chronic obstructive pulmonary disease referred to Allameh Bohlool Hospital in Gonabad, Iran in 2019. The participants were selected according to the inclusion criteria and were then randomly assigned to the two groups of intervention and placebo. Local packs were placed on the anterior of the chest twice a day for 23 minutes and for five days among the participants of both groups. The hot pack was 50ºC for the patients in the intervention group, but it was equal to body temperature in the placebo group. The severity of fatigue was once measured before the intervention and then one day after the final intervention in both groups. The demographic information form and Krupp fatigue severity scale were used to collect the data. Descriptive statistics and chi-square, MannWhitney, and Wilcoxon tests were used to analyze the data. Besides, the level of significance was considered at least 0.05. Results: The results indicated that the two groups were homogenous in terms of demographic information and the type of disease (P&gt;0.05). There was no statistically significant difference between the mean score of fatigue before the intervention in the experimental and placebo groups (P=0.9). However, the mean score of fatigue decreased significantly among the intervention group patients compared to those in the placebo group (P&lt;0.001) after the intervention. There was also a significant difference between the two groups in the mean score of fatigue before and after the intervention (P&lt;0.01). Conclusion: According to the results, topical heat therapy is effective in reducing fatigue among patients with COPD, but it is recommended to conduct further studies before the implementation of this approach.

Six weeks of localized heat therapy does not affect muscle mass, strength and contractile properties in healthy active humans.

Animal and human studies have shown that repeated heating may induce skeletal muscle adaptations, increasing muscle strength. The aim of this study is to investigate the effect of 6weeks of localized heating on skeletal muscle strength, volume and contractile properties in healthy humans. Fifteen active participants (8 males/7 females, 35 ± 6 years, 70 ± 14kg, 173 ± 7cm, average training of 87min per week) were subjected to 6weeks of single-leg heat therapy. Heat pads were applied for 8h/day, 5days/week, on one randomly selected calf of each participant, while the contralateral leg acted as control. The heat pads increased muscle temperature by 4.6 ± 1.2°C (p < 0.001). Every 2weeks, participants were tested for morphological (MRI), architectural (ultrasound), contractile (electrically evoked twitch), and force (isometric and isokinetic) adaptations. Repeated localized heating did not affect the cross-sectional area (p = 0.873) or pennation angle (p = 0.345) of the gastrocnemius muscles; did not change the evoked peak twitch amplitude (p = 0.574) or rate of torque development (p = 0.770) of the plantar flexors; and did not change maximal voluntary isometric (p = 0.214) or isokinetic (p = 0.973) plantar flexor torque. Whereas previous studies have observed improved skeletal muscle function following whole-body and localized heating in active and immobilized humans, respectively, the current data suggested that localized heating may not be a potent stimulus for muscle adaptations in active humans.

Local Heat Therapy to Accelerate Recovery After Exercise-Induced Muscle Damage.

The prolonged impairment in muscle strength, power, and fatigue resistance after eccentric exercise has been ascribed to a plethora of mechanisms, including delayed muscle refueling and microvascular and mitochondrial dysfunction. This review explores the hypothesis that local heat therapy hastens functional recovery after strenuous eccentric exercise by facilitating glycogen resynthesis, reversing vascular derangements, augmenting mitochondrial function, and stimulating muscle protein synthesis.

Skeletal muscle adaptations to heat therapy.

The therapeutic effects of heat have been harnessed for centuries to treat skeletal muscle disorders and other pathologies. However, the fundamental mechanisms underlying the well-documented clinical benefits associated with heat therapy (HT) remain poorly defined. Foundational studies in cultured skeletal muscle and endothelial cells, as well as in rodents, revealed that episodic exposure to heat stress activates a number of intracellular signaling networks and promotes skeletal muscle remodeling. Renewed interest in the physiology of HT in recent years has provided greater understanding of the signals and molecular players involved in the skeletal muscle adaptations to episodic exposures to HT. It is increasingly clear that heat stress promotes signaling mechanisms involved in angiogenesis, muscle hypertrophy, mitochondrial biogenesis, and glucose metabolism through not only elevations in tissue temperature but also other perturbations, including increased intramyocellular calcium and enhanced energy turnover. The few available translational studies seem to indicate that the earlier observations in rodents also apply to human skeletal muscle. Indeed, recent findings revealed that both local and whole-body HT may promote capillary growth, enhance mitochondrial content and function, improve insulin sensitivity and attenuate disuse-induced muscle wasting. This accumulating body of work implies that HT may be a practical treatment to combat skeletal abnormalities in individuals with chronic disease who are unwilling or cannot participate in traditional exercise-training regimens.

Effects of repeated local heat therapy on skeletal muscle structure and function in humans.

The purpose of the present study was to examine the effects of repeated exposure to local heat therapy (HT) on skeletal muscle function, myofiber morphology, capillarization, and mitochondrial content in humans. Twelve young adults (23.6 ± 4.8 yr, body mass index 24.9 ± 3.0 kg/m2) had one randomly selected thigh treated with HT (garment perfused with water at ~52°C) for 8 consecutive weeks (90 min, 5 days/wk) while the opposite thigh served as a control. Biopsies were obtained from the vastus lateralis muscle before and after 4 and 8 wk of treatment. Knee extensor strength and fatigue resistance were also assessed using isokinetic dynamometry. The changes in peak isokinetic torque were higher (P = 0.007) in the thigh exposed to HT than in the control thigh at weeks 4 (control 4.2 ± 13.1 Nm vs. HT 9.1 ± 16.1 Nm) and 8 (control 1.8 ± 9.7 Nm vs. HT 7.8 ± 10.2 Nm). Exposure to HT averted a temporal decline in capillarization around type II fibers (P < 0.05), but had no effect on capillarization indexes in type I fibers. The content of endothelial nitric oxide synthase was ~18% and 35% higher in the thigh exposed to HT at 4 and 8 wk, respectively (P = 0.003). Similarly, HT increased the content of small heat shock proteins HSPB5 (P = 0.007) and HSPB1 (P = 0.009). There were no differences between thighs for the changes in fiber cross-sectional area and mitochondrial content. These results indicate that exposure to local HT for 8 wk promotes a proangiogenic environment and enhances muscle strength but does not affect mitochondrial content in humans.NEW & NOTEWORTHY We demonstrate that repeated application of heat therapy to the thigh with a garment perfused with warm water enhances the strength of knee extensors and influences muscle capillarization in parallel with increases in the content of endothelial nitric oxide synthase and small heat shock proteins. This practical method of passive heat stress may be a feasible tool to treat conditions associated with capillary rarefaction and muscle weakness.

Abstract 043: Local Passive Heat in the Treatment of Nocturnal Supine Hypertension in Autonomic Failure

Supine hypertension affects about half of patients with primary autonomic failure (AF), complicates the treatment of orthostatic hypotension (OH) and induces nocturnal polyuria, resulting in worsening of morning OH. We previously showed that short exposure to local passive heat (40-42°C applied for ≤2 hours over abdomen and pelvis with a heating pad) acutely decreased systolic blood pressure (BP) by -25±5 mmHg in AF patients with supine hypertension due to decreases in stroke volume (-29±5%) and cardiac output (-30±5%). In this study, we hypothesized that local passive heat therapy applied overnight would lower nocturnal BP and polyuria, and improve early morning OH in these patients. Ten AF patients with supine hypertension (age 76±2 years, 6 men, supine systolic BP 168±3 mmHg) received passive heat (38°C with a water-perfused heating pad placed under the torso) or placebo, in a 2-night crossover study. Supine BP was monitored every 2 hr from 8pm-8am. Heat therapy was applied from 10pm-6am. Morning orthostatic tolerance was assessed at 8 am. Systolic BP significantly decreased during overnight heat therapy compared to placebo (Figure; P&lt;0.01 by mixed-effects model) with a maximal reduction of 30±6 mmHg at 4 hours of heat. Despite lowering nighttime BP, heat therapy did not decrease nocturnal diuresis or improve morning OH. In conclusion, low levels of local heat therapy applied overnight effectively lowers BP in AF patients with nocturnal supine hypertension. Thus, local heat therapy offers a novel non-pharmacologic approach to treat this condition, but future studies are needed to assess the long-term safety of this approach.

Impact of repeated local heat stress on skeletal muscle structure and function in humans

IntroductionShort‐term exposure to heat stress has been shown to enhance muscle strength and elicit mitochondrial adaptations in human skeletal muscle. We recently documented that exposure to five sessions of heat therapy (HT) accelerates the recovery of fatigue resistance following exercise‐induced muscle damage in humans. However, the long‐term impact of repeated exposure to local heat stress on contractile function and skeletal muscle structure remains unknown. The purpose of the present study was to examine the effects of 8 weeks of daily treatment with local HT on muscle strength, fatigability, fiber size and mitochondrial content in humans.MethodsTwelve healthy young adults (23.6±1.4 years, BMI 24.9±0.9 kg/m2) had one randomly selected thigh treated with daily HT for 8 consecutive weeks while the opposite thigh served as a control. A water‐circulating garment perfused with water at ~52ºC was used to apply HT for 90 min daily. Knee extensor strength (single peak torque during 3 repetition maximums at 180°/s and 60°/s) and fatigue resistance (total work during 40 repetition maximums at 180°/s) were assessed using isokinetic dynamometry before and after 4 and 8 weeks of treatment. Biopsies were obtained from the vastus lateralis muscle for the determination of myofiber cross‐sectional area and maximal citrate synthase activity.ResultsTreatment with HT elicited an increase in thigh skin temperature (39.8±0.1ºC), while skin temperature remained at baseline levels in the control thigh (32.4± 0.1ºC). A significant treatment effect was observed for the changes from baseline in peak isokinetic torque at 180º/s (p=0.04). On average, the changes in peak isokinetic torque from baseline for HT were ~2 fold higher than control at week 4 (Control: 4.1±3.7 Nm vs. HT: 9±4.6 Nm) and ~4 fold higher at week 8 (Control: 1.7±2.7 Nm vs. HT: 7.7±2.9 Nm). There were no differences between treatments for peak isokinetic torque at 60º/s, myofiber cross‐sectional area and citrate synthase activity.ConclusionThese results indicate that daily exposure to HT for 8 weeks enhances muscle strength in humans. Local HT may be a practical therapeutic approach to improve muscle function in individuals with limited mobility and skeletal muscle weakness.Support or Funding InformationSupport: American College of Sports Medicine Research EndowmentThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Impact of heat therapy on recovery after eccentric exercise in humans.

The purpose of this study was to investigate the effects of heat therapy (HT) on functional recovery, the skeletal muscle expression of angiogenic factors, macrophage content, and capillarization after eccentric exercise in humans. Eleven untrained individuals (23.8 ± 0.6 yr) performed 300 bilateral maximal eccentric contractions of the knee extensors. One randomly selected thigh was treated with five daily 90-min sessions of HT, whereas the opposite thigh received a thermoneutral intervention. Peak isokinetic torque of the knee extensors was assessed at baseline and daily for 4 days and fatigue resistance was assessed at baseline and 1 and 4 days after the eccentric exercise session. Muscle biopsies were obtained 2 wk before and 1 and 5 days after the eccentric exercise bout. There were no differences between thighs in the overall recovery profile of peak torque. However, the thigh exposed to HT had greater fatigue resistance than the thigh exposed to the thermoneutral intervention. The change from baseline in mRNA expression of vascular endothelial growth factor (VEGF) was higher at day 1 in the thigh exposed to HT. Protein levels of VEGF and angiopoietin 1 were also significantly higher in the thigh treated with HT. The number of capillaries around type II fibers decreased similarly in both thighs at day 5. Exposure to HT had no impact on macrophage content. These results suggest that HT accelerates the recovery of fatigue resistance after eccentric exercise and promotes the expression of angiogenic factors in human skeletal muscle. NEW & NOTEWORTHY We investigated whether exposure to local heat therapy (HT) accelerates recovery after a bout of eccentric exercise in humans. Compared with a thermoneutral control intervention, HT improved fatigue resistance of the knee extensors and enhanced the expression of the angiogenic mediators vascular endothelial growth factor and angiopoietin 1. These results suggest that HT hastens functional recovery and enhances the expression of regulatory factors involved in muscle repair after eccentric exercise in humans.

The Effect of Local Heat Therapy Method on Pain, Childbirth’s Outcomes, and Rate of Satisfaction in Primiparous Women: Randomize Clinical Trial

The Effect of Local Heat Therapy Method on Pain, Childbirth’s Outcomes, and Rate of Satisfaction in Primiparous Women: Randomize Clinical Trial