Physiologia, Volume 3, Issue 3 (September 2023) – 8 articles

Fibromyalgia (FM) is a chronic condition characterized by widespread chronic pain, muscle tenderness, chronic fatigue, and sleep disturbances. Treatment of FM focuses on the management of symptoms, often using medications, cognitive behavioral therapy, or moderate-to-high-intensity exercises (MHIE). MHIE is highly recommended by the current guidelines from the American College of Sports Medicine and the American Heart Association for people with FM to decrease comorbidities due to sedentary lifestyles. MHIE has also been shown to improve FM symptoms in individuals who can tolerate MHIE. However, individuals with FM present with one of the poorest adherences to MHIE. Most individuals with FM report symptoms worsening at the beginning of an MHIE intervention program. Objectives: This literature review aims to estimate the adherence to MHIE using dropout and compliance rates in individuals with FM who participated in studies that applied MHIE as an intervention and to examine possible reasons for high dropout rates and low compliance with MHIE programs, including psychological and physiological factors. Understanding the scope of potential dropout and compliance rates to MHIE intervention and factors that impact MHIE adherence in people with FM may help researchers and clinicians better design clinical trial studies and develop tailored exercise interventions according to individual patient characteristics. Conclusion: FM is a multi-faceted syndrome that can vary significantly in its presentation from person to person due to the complex duality of psychological and physiological factors. Consequently, clinicians should consider both components when prescribing exercises to FM patients. Full article

Low energy availability (LEA) is a complex health condition that most commonly affects female athletes. Research on LEA is weighted to quantitative approaches, and few studies have employed qualitative methods to understand the development of LEA. Current research fails to understand the complexity of LEA by largely operating within isolated research paradigms. This paper aims to demonstrate the value of integrating a mixed-methods research approach to understand the influence of sporting cultures on the physiological experiences of female athletes with LEA. The mixed-methods approach implemented the use of physiological (quantitative) and socio-psychological (qualitative) data obtained from elite female athletes in three sports: triathlons and running, (n = 11), rugby sevens (n = 9), and track cycling (n = 10). The physiological data consisted of energy availability, haematological analysis, bone health, and body composition. The socio-psychological data consisted of individual semi-structured interviews with topics covering nutrition, body image, the impact of the sporting environment, and experience with LEA. The interview data were thematically analysed. By bringing qualitative and quantitative data together, this paper illustrates the complex relationship between sporting culture and the physiology of LEA. First, endurance athletes categorised as having an LEA showed a positive correlation between the relative energy intake (EI) and serum ferritin, with the interviews revealing a focus on a low body weight and reducing the EI. Second, the interviews with the rugby players showed a strong but hierarchical team culture, with the experienced players monitoring and controlling the EI of novice players. Third, among the cyclists, the EI was reduced in those categorised as having an LEA, with the interviews revealing a coach–athlete power relationship impacting dietary behaviours. To conclude, this paper demonstrates how mixed methods are important for capturing how different sporting cultures impact athletes’ socio-psychological and physiological experiences of LEA. Full article

Chronic kidney disease (CKD) is characterised by poor physical function. Mechanical muscle properties such as tone, elasticity, and stiffness influence the functional state of the muscle. Measuring these muscle mechanical properties is difficult and data on CKD are sparse. Using a novel myotonometer device, the aims of this study were to compare the viscoelastic muscle properties in CKD patients with previously reported data and to explore the association with muscle function. Non-dialysis-dependent CKD participants were recruited into a cross-sectional study conducted between 2018 and 2020. Muscle properties (tone, stiffness, elasticity) were assessed using a myotonometer (MyotonPRO). Muscle function was assessed using physical performance tests (sit-to-stand 5 and 60, timed up and go, short physical performance battery, gait speed, incremental shuttle walk, postural sway). General linear regression models were used to explore the association between muscle properties and physical function. Thirty-nine participants were included (age 64.2 (SD: 10.4) years; 51% male; eGFR 40.9 (SD: 20.0) mL/min/1.73 m²). Participants with CKD had reduced muscle tone, stiffness, and elasticity compared to previously reported studies. Muscle tone (B = −0.567, p = 0.003) and muscle stiffness (B = −0.368, p = 0.071) were greater in males than females. Increased BMI was associated with lower muscle tone (B = −0.528, p = 0.002) and muscle stiffness (B = −0.577, p = 0.002). No meaningful nor consistent associations were found between these properties and measures of muscle function and physical performance. In conclusion, using a novel handheld myotonometer, this study found that CKD patients exhibit a reduction in muscle tone, stiffness, and elasticity. In a passive state, these viscoelastic muscle properties showed no consistent associations with physical performance. Full article

The purpose of this research was two-fold: (a) to observe whether highly trained adolescent swimmers abide to vitamin D supplement recommendations; and (b) to monitor changes in circulating 25-hydroxyvitamin D (25(OH)D) that occur between the autumn and winter months. Twenty swimmers (age: 17 ± 2 years) from a UK high-performance swimming club volunteered to complete two blood spot cards to determine their 25(OH)D concentration: the first in an autumn training phase (October) and the second during winter training (January). All swimmers were advised to consume vitamin D₃ supplements across the assessment period; however, only 50% of swimmers adhered to this recommendation. Resultantly, a winter decline in 25(OH)D was observed in non-supplementing swimmers (79.6 ± 25.2 to 52.6 ± 15.1 nmol·L⁻¹, p = 0.005), with swimmers either displaying an ‘insufficient’ (60%) or ‘deficient’ (40%) vitamin D status. In comparison, a greater maintenance of 25(OH)D occurred in supplementing swimmers (92.0 ± 25.5 to 97.2 ± 38.3 nmol·L⁻¹, p = 0.544), although variable outcomes occurred at the individual level (four increased, three maintained, three declined). These findings highlight the possible risks of vitamin D insufficiency during the winter for swimmers in the UK, possibly requiring standardised supplement practices. Moreover, alternative educational strategies may be required for swimmers to transfer knowledge to practice in order to improve supplement adherence in future. Full article

Lavender essential oil (EO) is widely used for medicinal purposes. The significant monoterpenes’ abundance of linalool and linalool acetate accounts for more than 50% of lavender EO compounds. Monoterpenes synthesis differs throughout plant development as a result of the differential gene expression patterns in distinct cell types. Previously, we have reported that the chemical composition of Lavandula angustifolia cv. etherio EO was affected by diurnal harvest time. The aim of this was to evaluate if the gene expression of lavender monoterpenes synthases is altered during the day length and correlated with the accumulation of the major components of lavender EO. The relative expression of linalool synthase (LaLINS), limonene synthase (LaLIMS) and terpene synthase-like (LaTPS-l) was recorded in flowers at the 3rd to 5th stage every 3 h during two consecutive days using quantitative real-time PCR. The composition of the lavender EO was also monitored during the day length using GC-MS analysis. Our results indicate that the expression of genes involved in the synthesis of lavender EO, including linalool and limonene synthases, is accompanied by oscillations, picking at mid-day and leading to linalool acetate accumulation in the afternoon. In conclusion, the monoterpenes synthase expression in lavender flowers is rhythmically affected during the day, leading to a higher accumulation of EO compounds in the afternoon. These results will be helpful to monitor the biosynthesis of lavender EO to ensure a high-quality product. Furthermore, the outcome of this study will be useful for breeding programs in the lavender field to modulate the biosynthesis of linalool and linalool acetate during the flowering harvest period. Full article

Background: Lumbar spinal stenosis causes considerable disability in everyday life; its incidence is increasing due to aging in the world population. First-line treatment is generally conservative, but rehabilitation outcome is still unclear; the aim of this systematic review was to define which domains need to be evaluated for the lumbar stenosis physiotherapy approach, further specifying if the literature suggests patient-centred or objective measures. Methods: A systematic review of the literature according to the PRISMA statement was carried out; the PICO model was used to draw research questions. RCTs about the rehabilitation of lumbar spinal stenosis conducted in the last five years were considered includible, with no difference in terms of stenosis location. The following databases were screened through specific search strings: PubMed, EBSCO, PEDro, Cochrane Database, Scopus, and Google Scholar; two independent researchers assessed results and a third opinion was requested to solve conflicts. Critical appraisal of the included studies was conducted through Pedro Jadad scores. The following data were extracted: author and year, country, sample, intervention, outcome domains, and tools. Results: From 10,069 records, three RCTs were included in the final review stage; they all showed high methodological quality. It is recommended for physiotherapists dealing with lumbar spinal stenosis to assess five main domains: disability, pain, clinical tests, mental wellbeing and kynesiophobia, and quality of life. Domains were mainly assessed through self-reported questionnaires/scales, while objective tests evaluate general lower limb movements, the active range of motion, or the muscles’ endurance. Conclusion: This five-domain evaluation model is reliable and can be practised in each rehabilitation setting (home, outpatient, and hospital); sustainability is guaranteed by the prevalent employment of self-reported tools. Future studies should evaluate the best questionnaire/scale for each domain, especially the definition of a gold standard for pain assessment in patients with lumbar stenosis as this is a challenge for the future. Full article

We examined sex differences in behavioral responses to fear-related learning through ultrasonic vocalization. Adult male and female rats of two inbred rat strains (WAG/Rij rats with genetic predisposition absence epilepsy, n = 25; and the minor substrain NEW with non-epileptic phenotype, n = 32) were examined in the two-way active avoidance task (50 trials). Three behavioral responses were defined: successful learning, unsuccessful learning, and freezing (motionless behavior). We found that males were more likely to experience freezing (40%) than females (3.7%). Females performed significantly better than males: 93% of females showed “successful learning”, while only 43.2% of males did. Long-lasting 22 kHz ultrasonic calls, so-called aversive ultrasonic vocalizations aUSVs, were recorded in 26% of females (only successful learners) and in 50% of males. The density of aUSVs in females was lower than in males. WAG/Rij males performed much poorer than the NEW males. In general, males, in contrast to females, showed significantly poorer avoidance learning, more frequently experienced freezing, and produced more aversive USVs. Males thus experienced a negative emotional state, rather than exhibiting poor cognitive abilities. Perhaps, WAG/Rij rats and a minor NEW substrain showed an increased emotionally in fear-related tasks, because they are prone to emotional disorders or emotional exhaustion. Sex differences in freezing and in aUSVs might result from the poorly understood neuromodulatory effects of the cholinergic system. Full article

The purpose of the present study was to investigate the effect of ischemic preconditioning (IPC) on the recovery of exercise performance following maximal, incremental exercise. A total of 13 healthy males volunteered to participate, undertaking three experimental trials involving a constant work-rate bout of severe intensity exercise undertaken to the limit of tolerance that was preceded by a 40-min recovery period consequent to a maximal, incremental exercise test. During the recovery period, participants underwent IPC at 220 mmHg, sham IPC (SHAM; 20 mmHg), and passive rest (CON). Exercise tolerance time was higher following IPC as compared to SHAM and CON {199 ± 36 (CON) vs. 203 ± 35 (SHAM) vs. 219 ± 34 (IPC), p = 0.03}. This effect was accompanied by a tendency toward an augmented increase in blood lactate from rest to exercise in IPC compared to SHAM and CON (p = 0.08). There was no effect of IPC on oxygen uptake kinetics or muscle oxygenation as indicated via near-infrared spectroscopy. IPC may therefore have the capacity to augment recovery from prior maximal exercise, but this does not appear to be due to enhancements to oxygen uptake kinetics or muscle oxygenation. Full article