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Background: Swallowing is triggered when a food bolus being prepared by mastication has reached a defined state. However, although this view is consensual and well supported, the physical properties of the swallowable bolus have been under-researched. We tested the hypothesis that measuring bolus physical changes during the masticatory sequence to deglutition would reveal the bolus properties potentially involved in swallowing initiation. Methods: Twenty normo-dentate young adults were instructed to chew portions of cereal and spit out the boluses at different times in the masticatory sequence. The mechanical properties of the collected boluses were measured by a texture profile analysis test currently used in food science. The median particle size of the boluses was evaluated by sieving. In a simultaneous sensory study, twenty-five other subjects expressed their perception of bolus texture dominating at any mastication time. Findings: Several physical changes appeared in the food bolus as it was formed during mastication: (1) in rheological terms, bolus hardness rapidly decreased as the masticatory sequence progressed, (2) by contrast, adhesiveness, springiness and cohesiveness regularly increased until the time of swallowing, (3) median particle size, indicating the bolus particle size distribution, decreased mostly during the first third of the masticatory sequence, (4) except for hardness, the rheological changes still appeared in the boluses collected just before swallowing, and (5) physical changes occurred, with sensory stickiness being described by the subjects as a dominant perception of the bolus at the end of mastication. Conclusions: Although these physical and sensory changes progressed in the course of mastication, those observed just before swallowing seem to be involved in swallowing initiation. They can be considered as strong candidates for sensory inputs from the bolus that are probably crucially involved in the triggering of swallowing, since they appeared in boluses prepared in various mastication strategies by different subjects.

The objective of the present study was to assess the impact of age and dentition status on masticatory function. A three-arm case–control study was performed. Group 1 (n 14) was composed of young fully dentate subjects (age 35·6 ± 10·6 years), group 2 (n 14) of aged fully dentate subjects (age 68·8 ± 7·0 years) and group 3 (n 14) of aged full denture wearers (age 68·1 ± 7·2 years). Mastication adaptation was assessed in the course of chewing groundnuts and carrots to swallowing threshold. Particle size distribution of the chewed food, electromyographic (EMG) activity of the masseter and temporalis muscles during chewing, and resting and stimulated whole saliva rates were measured. Aged dentate subjects used significantly more chewing strokes to reach swallowing threshold than younger dentate subjects (P < 0·05), with increased particle size reduction, longer chewing sequence duration (P < 0·05) and greater total EMG activity (P < 0·05) for both groundnuts and carrots. In addition, aged denture wearers made significantly more chewing strokes than aged dentate subjects (P < 0·001) to reach swallowing threshold for groundnuts. Particle size reduction at time of swallowing was significantly poorer for denture wearers than for their aged dentate counterparts, despite an increase in chewing strokes, sequence duration and EMG activity per sequence. Masticatory function was thus adapted to ageing, but was impaired in denture wearers, who failed to adapt fully to their deficient masticatory apparatus.

We hypothesized that interindividual differences in motor activities during chewing and/or swallowing were determining factors for the transfer of volatile aroma from the in-mouth air cavity (IMAC) toward the olfactory mucosa. In our first experiment, we looked for changes in IMAC volume after saliva deglutition in 12 healthy subjects. The mean IMAC volume was measured after empty deglutition using an acoustic pharyngometer device. Based on the time course of the IMAC volume after swallowing, we discerned two groups of subjects. The first group displayed a small, constant IMAC volume (2.26 mL ±0.62) that corresponded to a high tongue position. The second group displayed a progressive increase in IMAC (from 6.82 mL ±2.37 to 22.82 mL ±3.04) that corresponded to a progressive lowering of the tongue to its resting position. In our second experiment, we investigated the relationship between IMAC volume changes after deglutition and the level of aroma release at the nostril. For this purpose, the release of menthone was measured at the nostril level in 25 subjects who consumed similar amounts of a mint tablet. The subjects were separated into two groups corresponding to two levels of menthone release: high (H) and low (L). The mean volume of IMAC was measured during and after empty deglutition. Group H displayed a small, constant amplitude of IMAC volume change after deglutition, while Group L displayed a progressive increase in IMAC. It is likely that Group H continuously released the aroma through the veloglossal isthmus as the mint was consumed, while Group L trapped the aroma in the oral cavity and then released it into the nasal cavity upon swallowing. These results show that the in vivo aroma release profile in humans depends closely on the different motor patterns at work during empty deglutition.

We studied the effects of a specific cardio training program lasting 5 years on pain and quality of life in fibromyalgia patients. Method: An observational longitudinal pilot study was conducted in 138 fibromyalgia women. Fibromyalgia women recruited were asked to carry out three sessions per week, each lasting 45 min, of moderate-intensity continuous training (64%–75% Maximal Heart rate [HRmax]). During the first year, the patients progressively increased their training intensity. During the last 2 years, the patients were asked to associate moderate-intensity continuous training and high-intensity interval training (85%–90% HRmax). Pain on a visual analog scale, anxiety and depression state on the Hospital Anxiety and Depression Scale, impact of fibromyalgia on daily life using the Fibromyalgia Impact Questionnaire, heart rate and sleep quality (visual analog scale) were assessed at baseline and each year for 5 years. Results: Forty-nine patients dropped out in the first year. Depending on their training status, the remaining 89 patients were retrospectively assigned to one of the three groups: Active (moderate-intensity continuous training), Semi-Active (one or two sessions, low-intensity continuous training <60% HRmax) and Passive (non-completion of training), based on their ability to comply with the program. Alleviation of all symptoms (p < 0.0001) was observed in the Active group. Increasing exercise intensity enhanced the effects obtained with moderate-intensity continuous training. Significant change in the Fibromyalgia Impact Questionnaire (p < 0.0001) and depression (Hospital Anxiety and Depression Scale; p < 0.0001), and no significant decrease in pain were noted in the Semi-Active group. No effect of the training was observed in the Passive group. Conclusion: The study intervention associated with multidisciplinary care alleviated pain, anxiety and depression, and improved both quality of life and quality of sleep, in fibromyalgia patients.

The main function of mastication is to transform a solid food into a bolus that can be swallowed safely. The bolus characteristics such as particles size or cohesiveness, are continuously sensed during mastication and they are important in initiating deglutition. This study examined the following question: What is the condition of the bolus just before swallowing? Ten subjects with normal dentition aged 37.5 +/- 3.7 years were asked to chew without swallowing six different foods (three nuts and three vegetables) while the number of cycles and the duration of the sequence were recorded. The particle size distribution shown by the expectorated food bolus just before swallowing was examined by image analysis. The results showed that, for a given food, the sizes of the bolus particles just before swallowing were comparable in all subjects. However, the number of cycles and duration of the sequence varied between subjects. Taken together these data strongly suggest that the granularity of the bolus before swallowing has to reach a predetermined state which is obtained by using an individual chewing strategy. This suggests that the bolus structure reflects a key factor for homeostasis and explains the large interindividual variability of the mastication physiologic parameters.

Objectives The tongue-to-palate distance influences the volume of the in-mouth air cavity (IMAC), thus condition- ing the entry of aromatic compounds to the olfactory mucosa site. This study was set out to record the IMAC volume by measuring tongue-to-palate distance at rest. Materials and methods Twelve young adults in good general health were tested -- lips contacting, with at-rest posture of the tongue and jaw during a silent reading task. Observations in this study were limited to pre- and post-swallowing sequences. The tongue-to-palate distance was measured using three electromagnetic sensors placed on the tongue upper surface. IMAC volume was evaluated from a geometrical model, taking into account the tongue-to-palate distance, the IMAC transversal distance measured from dental casts and historic data giving the anterior - posterior distance of the oral cavity. Results (1) In the at-rest posture, the tongue-to-palate distance was significantly greater at the posterior sensor level. (2) A vertical shift in tongue posture at rest frequently appeared following deglutition. The upward shifts were of larger amplitude and more frequent than the downward shifts. (3) Evaluation of the IMAC volume gave an approximate value of 12 ml at rest. (4) The chin sensor at rest was 2.8±0.8 mm below its position when in occlusion

Passive music listening has shown its capacity to soothe pain in several clinical and experimental studies. This phenomenon—known as music-induced analgesia—could partly be explained by the modulation of pain signals in response to the stimulation of brain and brainstem centers. We hypothesized that music-induced analgesia may involve inhibitory descending pain systems. We assessed pain-related responses to endogenous pain control mechanisms known to depend on descending pain modulation: peak of first pain (PP), temporal summation (TS), and diffuse noxious inhibitory control (DNIC). Twenty-seven healthy participants (14 men, 13 women) were exposed to a conditioned pain modulation paradigm during a 20-minute relaxing music session and a silence condition. Pain was continually measured with a visual analogue scale. Pain ratings were significantly lower with music listening (p < .02). Repeated measures ANOVA indicated significant differences between conditions within PP and TS (p < .05) but not in DNIC. Those findings suggested that music listening could strengthen components of the inhibitory descending pain pathways operating at the dorsal spinal cord level.

Passive music listening has shown its capacity to soothe pain in several clinical and experimental studies. This phenomenon—known as music-induced analgesia—could partly be explained by the modulation of pain signals in response to the stimulation of brain and brainstem centers. We hypothesized that music-induced analgesia may involve inhibitory descending pain systems. We assessed pain-related responses to endogenous pain control mechanisms known to depend on descending pain modulation: peak of first pain (PP), temporal summation (TS), and diffuse noxious inhibitory control (DNIC). Twenty-seven healthy participants (14 men, 13 women) were exposed to a conditioned pain modulation paradigm during a 20-minute relaxing music session and a silence condition. Pain was continually measured with a visual analogue scale. Pain ratings were significantly lower with music listening (p < .02). Repeated measures ANOVA indicated significant differences between conditions within PP and TS (p < .05) but not in DNIC. Those findings suggested that music listening could strengthen components of the inhibitory descending pain pathways operating at the dorsal spinal cord level.

IntroductionThe main symptom of fibromyalgia (FM) is diffuse pain. There is currently no aetiological treatment for FM. However, all pain associations and best practice guidelines strongly advocate the practice of aerobic physical activity to improve the symptoms of FM subjects. The mechanisms of dysfunctional pain are mostly central and related to stress axis dysfunction (autonomic nervous system and corticotropic axis). Our main objective is to assess the efficacy of a specific training programme on endogenous pain control mechanisms in female patients with FM. Further aims include rebalancing the autonomic neurovegetative system, improving quality of life and sleep quality, and reintegrating patients into society and work.Methods and analysis110 female patients with FM diagnosed on American College of Rheumatology 2010 criteria, aged 18–65 years and meeting inclusion conditions will be recruited and randomised into two groups (active and semiactive). The training programme will consist of three 45 min sessions per week of supervised, individualised physical activity over 2 years. Only the intensity of the exercises will differ between the two groups (moderate intensity vs low intensity).All outcome measures will be conducted at baseline (T0), after 6–9 months of training (T6–9) and after 24 months of training (T24). The primary endpoint will be an improvement of pain modulation (activation of diffuse noxious inhibitory control) evaluated by the stimulation test. The secondary endpoint will be relief of pain, anxiety, depression, stress, sleep disorders, pain impact on life quality, and improved heart rate, blood pressure and salivary cortisol.Ethics and disseminationThis study is approved by the Committee for the Protection of Persons West VI. The results will be published in specialised scientific journals and will be presented at scientific meetings on pain and/or physical activity.Trial registration number NCT02486965; Pre-results.

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