High-intensity interval training for chronic pain conditions: a narrative review

How Do Peripheral Neurons and Glial Cells Participate in Pain Alleviation by Physical Activity?

Chronic pain is a global health problem with major socioeconomic implications. Drug therapy for chronic pain is limited, prompting search for non-pharmacological treatments. One such approach is physical exercise, which has been found to be beneficial for numerous health issues. Research in recent years has yielded considerable evidence for the analgesic actions of exercise in humans and experimental animals, but the underlying mechanisms are far from clear. It was proposed that exercise influences the pain pathways by interacting with the immune system, mainly by reducing inflammatory responses, but the release of endogenous analgesic mediators is another possibility. Exercise acts on neurons and glial cells in both the central and peripheral nervous systems. This review focuses on the periphery, with emphasis on possible glia-neuron interactions. Key topics include interactions of Schwann cells with axons (myelinated and unmyelinated), satellite glial cells in sensory ganglia, enteric glial cells, and the sympathetic nervous system. An attempt is made to highlight several neurological diseases that are associated with pain and the roles that glial cells may play in exercise-induced pain alleviation. Among the diseases are fibromyalgia and Charcot-Marie-Tooth disease. The hypothesis that active skeletal muscles exert their effects on the nervous system by releasing myokines is discussed.

Exploring the impact of vitamin D on tendon health: a comprehensive review

Tendons are vital components of the musculoskeletal system, facilitating movement and supporting mechanical loads. Emerging evidence suggests that vitamin D, beyond its well-established role in bone health, exerts significant effects on tendon physiology. The aim of this manuscript is to review the impact of vitamin D on tendons, focusing on its mechanisms of action, clinical implications, and therapeutic applications. A comprehensive search of scientific electronic databases was conducted to identify articles on the effects of vitamin D on tendon health. Fourteen studies were included in this review. Five studies were performed in vitro, and nine studies were conducted in vivo. Despite some conflicting results, the included studies showed that vitamin D regulates collagen synthesis, inflammation, and mineralization within tendons through its interaction with vitamin D receptors. Epidemiological studies link vitamin D deficiency with tendon disorders, including tendinopathy and impaired healing. Supplementation with vitamin D shows promise in improving tendon strength and function, particularly in at-risk populations such as athletes and the elderly. Future research should address optimal supplementation strategies and explore the interplay between vitamin D and other factors influencing tendon health. Integrating vitamin D optimization into clinical practice could enhance tendon integrity and reduce the burden of tendon-related pathologies.

Changes in pain perception during pregnancy after one-time maximal physical exertion and an 8-week high-intensity interval training

Background: Pain, a subjective sensation, poses a great challenge to the human body as a stressor. There is empirical evidence that moderate to intense physical activity increases pain tolerance and this may be critical during pregnancy for optimal pregnancy, fetal development, and delivery. To the best of our knowledge, it is the first study examining the changes in pain perception in pregnant women after a maximal progressive exercise test and after 8 weeks of high-intensity interval training (HIIT). Methods: Thirty-five women with uncomplicated singleton pregnancies between 13 and 28 weeks of gestation participated in the study. The HIIT intervention was developed in accordance with the recommendations and available data on HIIT during pregnancy. The maximal progressive cardiopulmonary exercise test was performed on a cycle ergometer with an electronically controlled load. Pressure pain threshold and pressure pain tolerance were measured with an algometer. Results: We found significant effects of the maximal exercise test and high-intensity interval training, such that the pregnant women had higher pain tolerance after the maximal exercise test than before and after the high-intensity interval training than the baseline. Conclusion: Our results suggest that post-exercise analgesia may be important in pregnant women and that high-intensity interval training appears to be beneficial for pregnant women to improve their pain tolerance while being obstetrically safe. Increased pain tolerance before labor could lead to better management of pain during labor and in the postpartum and lactation periods. Increasing pregnant women's awareness of this issue can improve their wellbeing and provide more comfort during labor.

Analysis of Japanese nationwide health datasets: association between lifestyle habits and prevalence of neuropathic pain and fibromyalgia with reference to dementia-related diseases and Parkinson's disease

OBJECTIVES

Chronic pain is defined as pain that persists or recurs for more than 3 months. This study focuses on neuropathic pain (NP) and fibromyalgia (FM) which are chronic pain states, and aims to identify lifestyle habits associated with their prevalence. Other neurological disorders are also analyzed as references.

METHODS

Association between the variable referring to disease prevalence (number of claims for reimbursement of marker drugs) and the variable for lifestyle habits/health examination results (collected from insured individuals aged 40-74 years) was determined by analyzing Japanese nationwide datasets, which were collected in 2018 and aggregated by prefecture. Pregabalin, donepezil, and levodopa were used as marker drugs for the chronic pain states, dementia-related diseases (Alzheimer's disease and Lewy body dementia) and Parkinson's disease (PD), respectively. Pearson's correlation analysis and multiple linear regression analysis were conducted.

RESULTS

Variables showing correlation coefficient (|r|)>0.5 were put into the multiple linear regression. Exercise habits (ꞵ=-0.3182), smoking habits (0.3218), daily drinking (0.2683), and alanine aminotransferase>51 U/L (0.2309) were finally incorporated in the equation for pregabalin (R 2=0.7268). Walking speed (-0.4543) and daily drinking (0.5077) were incorporated in the equation for donepezil (R 2=0.5718).

CONCLUSIONS

The prevalence of chronic pain states is associated with lifestyle habits, just like the dementia-related diseases. Exercise in daily life is negatively associated with the prevalence of the chronic pain states, although excessive alcohol drinking, smoking, and high serum ALT are positively associated with it. The prevalence of PD seems less associated with lifestyle habits.

Therapeutic Exercise Parameters, Considerations and Recommendations for the Treatment of Non-Specific Low Back Pain: International DELPHI Study

BACKGROUND

Therapeutic exercise (TE) recommendations for non-specific low back pain (LBP) are meant to support therapy choices for people who suffer from this condition. The aim of this study was to reach an agreement on the definition and use of TE in the care of people with LBP.

METHODS

A Delphi study was carried out with a formal consensus procedure and sufficient scientific evidence, using an established methodology. Four rounds of anonymous questionnaires were administered to create useful suggestions and instructions in terms of the therapeutic activity for patients with LBP, and a group consensus conference.

RESULTS

A consensus was reached on most of the questions after 35 physiotherapists completed the questionnaires. Participants agreed that proper TE requires correct posture, body awareness, breathing, movement control, and instruction. Patients with LBP were advised to participate in supervised sessions twice a week for 30 to 60 min for a period of 3 to 6 months. Participants added that tailored evaluation and exercise prescription, monitoring, and functional integration of exercise, as well as using specific equipment, would benefit patients with LBP.

CONCLUSIONS

TE recommendations for patients with LBP should be dosed and customized based on their personal psychological needs, level of fitness, and kinesiophobia.

High-Intensity Training for Knee Osteoarthritis: A Narrative Review

Knee osteoarthritis (OA) is the most common joint disease worldwide. Exercise therapy has been identified as a first-line treatment option in patients suffering from knee OA. High-intensity training (HIT) is an innovative exercise modality with potential in improving various disease-related outcomes. The purpose of this review is to explore the impact of HIT on knee OA symptoms and physical functioning. A comprehensive search of scientific electronic databases was conducted to identify articles on the effects of HIT on knee OA. Thirteen studies were included in this review. Ten compared the effects of HIT with those of low-intensity training, moderate-intensity continuous training, or a control group. Three evaluated the effects of HIT alone. Eight reported a decrease in knee OA symptoms (especially pain), and eight reported an increase in physical functioning. HIT was shown to improve knee OA symptoms and physical functioning, but also aerobic capacity, muscle strength, and quality of life with minimal or no adverse events. However, compared with other exercise modalities, no clear superiority of HIT was found. HIT is a promising exercise strategy in patients with knee OA; nonetheless, the actual quality of evidence remains very low, and more high-quality studies are needed to confirm these promising outcomes.

Effects of weight-bearing vs. non-weight-bearing endurance exercise on reducing body fat and inflammatory markers in obese females

OBJECTIVES

Endurance exercise is an effective strategy for maintaining an anti-inflammatory environment and weight management. However, the effect of this type of exercise on decreasing body fat and TNF-α levels and increasing adiponectin levels is controversial. The aims of this study was to prove the effects of weight-bearing vs. non-weight-bearing endurance exercise on reducing body fat and inflammatory markers in obese females.

METHODS

24 obese adolescents were recruited from female students from the State University of Malang. The interventions given in this study were weight-bearing endurance exercise (WBEE), and non-weight-bearing endurance exercise (NWBEE). Serum TNF-α levels and serum adiponectin levels were evaluated using enzyme-linked immunosorbent assay (ELISA). Statistical analysis techniques use paired sample T-test with a significant level of 5%.

RESULTS

Results of the statistical analysis show that the average body fat (PBF, FM, FFM) and TNF-α levels before endurance exercise vs. after endurance exercise in both types of exercise experienced a significant decrease (p≤0.05), while average adiponectin levels in both types of exercise experienced a significant increase before endurance exercise vs. after endurance exercise (p≤0.001).

CONCLUSIONS

In general, it can be concluded that weight-bearing and non-weight-bearing endurance exercise with moderate-intensity for 40 min/exercise session reduce body fat and TNF-α levels and increase adiponectin levels as a marker of inflammation in obese female.

Physiological response of endurance exercise as a growth hormone mediator in adolescent women's

OBJECTIVES

Overweight status decreases the growth hormone (GH) secretion, thus, increasing the risk factors for medical complications. However, proper exercise is reported to enhance GH and affect the energy balance. Therefore, exercise is proclaimed to be an accurate and engaging therapy to increase GH in preventing overweight. This study aims to investigate the physiological response of exercise in mediating the increase of GH secretion in female adolescents.

METHODS

22 overweight women aged 19-20 years old, with maximal oxygen consumption of 27-35 mL/kg/min, were selected as sample size. They were divided into three groups, namely (CONT, n=7) Control, (MIEE, n=7) Moderate-intensity interval endurance exercise, and (MCEE, n=8) Moderate-intensity continuous endurance exercise. The exercise was carried out by running for 30-35 min using treadmills with an intensity of 60-70% HR_max. The blood sampling for GH examination was carried out four times before exercise, 10 min, 6 h, and 24 h after exercise. The enzyme-linked immunosorbent assay (ELISA) was used to measure the GH and IGF-1 levels. The data analysis was carried out using a one-way ANOVA test, with a significance level of 5%.

RESULTS

The results of the one-Way ANOVA test suggested a significantly different average GH and IGF-1 before and after the exercise between the three groups (CON, MIEE, and MCEE) (p≤0.05).

CONCLUSIONS

MCEE increases the GH and IGF-1 levels more considerably than MIEE. Therefore, exercise is a mediator to increase GH and IGF-1 secretion in overweight individuals. Exercise could be a viable therapy for overweight people.

Aerobic and Anaerobic Fitness according to High-Intensity Interval Training Frequency in Youth Soccer Players in the Last Stage of Rehabilitation

In the last stage of rehabilitation, high-intensity interval training (HIIT) for improving physical fitness is appropriate for return-to-play; however, some youth athletes visit the rehabilitation center less frequently due to conflict with their distance to center, and academic schedule. We tested the effects of short-term low-frequency HIIT in 54 youth male soccer players, after dividing them into a low-frequency group (LFG, n = 27 players) and a high-frequency group (HFG, n = 27 players). Muscle mass and body fat were measured using a body composition test, and VO₂peak and exercise duration were measured using a treadmill. Five sets of anaerobic peak power and fatigue were measured repeatedly using the Wingate test. To evaluate knee joint muscle function, 60°/s, 180°/s, and 240°/s were measured using the isokinetic muscle function equipment. HIIT sessions were conducted twice a week for LFG and five times a week for HFG for 4 weeks. In this study, Wilcoxon signed-rank test and Mann-Whitney U test were mainly used for analysis. Significant improvements in VO₂peak, anaerobic peak power, and knee strength were observed after intervention in both groups (p < 0.05). In the post test, there were significant differences between groups in VO₂peak (LFG, 56.4 vs. HFG, 57.1 mL/kg/min; p = 0.035), exercise duration (LFG, 972.3 vs. HFG, 990.4 s; p = 0.041), Wingate anaerobic peak power 5 sets (LFG, 606.3 vs. HFG, 629.3 Watt; p = 0.039), and muscle function test 240°/s (LFG, 68.5 vs. HFG, 70.2 Jouls; p = 0.010). However, neither group showed significant changes in body composition, such as muscle mass or body fat (p > 0.05). In conclusion, although it is a short-term training, the effect of HIIT was shown in the HFG as well as LFG. Although HFG improved physical fitness, significant improvement was also achieved in LFG. Therefore, in the last stage of rehabilitation, low frequency as well as high frequency HIIT would be an appropriate training method to improve physical fitness for youth soccer players.

The impact of high-intensity interval training on vascular function in adults: A systematic review and meta-analysis

Aim

We performed a systematic review and meta-analysis to investigate the effects of high-intensity interval training (HIIT) compared with moderate-intensity continuous training (MICT) or with no exercise (CON) on vascular function in adults who were free of cardiometabolic diseases and those with cardiometabolic diseases.

Methods

A search across three electronic databases including Scopus, PubMed, and Web of Science was conducted through February 2022 to identify the randomized trials evaluating HIIT vs. MICT and/or CON on vascular function as measured using brachial artery flow-mediated dilation (FMD) in adults. Separate analyses were conducted for HIIT vs. MICT and/or CON to calculate weighted mean differences (WMD) and 95% confidence intervals (95% CIs) using random or fixed models.

Results

A total of 36 studies involving 1,437 participants who were either free of cardiometabolic diseases or had cardiometabolic diseases were included in the meta-analysis. HIIT effectively increased FMD when compared with MICT [1.59% (95% CI 0.87-2.31), p = 0.001] or CON [3.80% (95% CI 2.58-5.01), p = 0.001]. Subgroup analysis showed that HIIT increased FMD in participants with cardiovascular and metabolic diseases, but not in participants who were free of cardiometabolic diseases. In addition, HIIT effectively increased FMD regardless of age and body mass index.

Conclusion

We confirm that HIIT is effective for improving vascular function in individuals with metabolic disorders and cardiovascular diseases and has a superior effect compared to MICT, demonstrating time efficiency.

Systematic review registration

[https://www.crd.york.ac.uk/prospero], identifier [CRD42022320863].