Brain plasticity after rehabilitation in a severe case of artery of Percheron stroke assessed with multimodal MR imaging.

Artery of Percheron (AOP) stroke is a rare event. We describe an AOP stroke involving both thalami and the midbrain, resulting in a multifunctional clinical impairment. Intensive inpatient multidisciplinary rehabilitation favored the recovery of motor deficits, together with the improvement of cognitive dysfunctions. MRI assessment in the chronic post-stroke phase showed structural and functional reorganization in response to the extended thalamic tissue damage and absence of revascularization. Thalamo-cortical networks involving frontal and prefrontal regions, as well as parietal areas were disrupted, whereas increased functional thalamo-occipital connectivity was found. This report sheds light on brain reorganization following AOP stroke after rehabilitation..

Facilitators and barriers to adaptive implementation of the Meeting Centers Support Program (MCSP) in three European countries; the process evaluation within the MEETINGDEM study.

ABSTRACTBackground:In the MEETINGDEM project, the Meeting Centers Support Program (MCSP) was adaptively implemented and evaluated in three European countries: Italy, Poland, and the United Kingdom. The aim of this study was to investigate overall and country-specific facilitators and barriers to the implementation of MCSP in these European countries. METHODS: A qualitative multiple case study design was used. Based on the theoretical model of adaptive implementation, a checklist was composed of potential facilitators and barriers to the implementation of MCSP. This checklist was administered among stakeholders involved in the implementation of MCSP to trace the experienced facilitators and barriers. Twenty-eight checklists were completed. RESULTS: Main similarities between countries were related to the presence of suitable staff, management, and a project manager, and the fact that the MCSP is attuned to needs and wishes of people with dementia and informal caregivers. Main differences between countries were related to: communication with potential referrers, setting up an inter-organizational collaboration network, receiving support of national organizations, having clear discharge criteria for the MCSP and continuous PR in the region. CONCLUSION: The results of this study provide insight into generic and country specific factors that can influence the implementation of MCSP in different European countries. This study informs further implementation and dissemination of MCSP in Europe and may also serve as an example for the dissemination and implementation of other effective psychosocial support interventions for people with dementia and their informal caregivers across and beyond Europe.

Not re-inventing the wheel: the adaptive implementation of the meeting centres support programme in four European countries.

OBJECTIVES: The implementation of new health services is a complex process. This study investigated the first phase of the adaptive implementation of the Dutch Meeting Centres Support Programme (MCSP) for people with dementia and their carers in three European countries (Italy, Poland, the UK) within the JPND-MEETINGDEM project. Anticipated and experienced factors influencing the implementation, and the efficacy of the implementation process, were investigated. Findings were compared with previous research in the Netherlands. METHOD: A qualitative multiple case study design was applied. Checklist on anticipated facilitators and barriers to the implementation and semi-structured interview were completed by stakeholders, respectively at the end and at the beginning of the preparation phase. RESULTS: Overall, few differences between countries were founded. Facilitators for all countries were: added value of MCSP matching needs of the target group, evidence of effectiveness of MCSP, enthusiasm of stakeholders. General barriers were: competition with existing care and welfare organizations and scarce funding. Some countries experienced improved collaborations, others had difficulties finding a socially integrated location for MCSP. The step-by-step implementation method proved efficacious. CONCLUSION: These insights into factors influencing the implementation of MCSP in three European countries and the efficacy of the step-by-step preparation may aid further implementation of MCSP in Europe.

Technology-enhanced multi-domain at home continuum of care program with respect to usual care for people with cognitive impairment: the Ability-TelerehABILITation study protocol for a randomized controlled trial.

BACKGROUND: According to the World Alzheimer Report (Prince, The Global Impact of Dementia: an Analysis of Prevalence, Incidence, Cost and Trends, 2015), 46.8 million people worldwide are nowadays living with dementia. And this number is estimated to approximate 131.5 million by 2050, with an increasing burden on society and families. The lack of medical treatments able to stop or slow down the course of the disease has moved the focus of interest toward the nonpharmacological approach and psychosocial therapies for people with/at risk of dementia, as in the Mild Cognitive Impairment (MCI) condition. The purpose of the present study is to test an individualized home-based multidimensional program aimed at enhancing the continuum of care for MCI and outpatients with dementia in early stage using technology. METHODS: The proposed study is a single blind randomized controlled trial (RCT) involving 30 subjects with MCI and Alzheimer's disease (AD) randomly assigned to the intervention group (Ability group), who will receive the "Ability Program", or to the active control group (ACG), who will receive "Treatment As Usual" (TAU). The protocol provides for three steps of assessment: at the baseline (T_0), after treatment, (T_1) and at follow-up (T_2) with a multidimensional evaluation battery including cognitive functioning, behavioral, functional, and quality of life measures. The Ability Program lasts 6 weeks, comprises tablet-delivered cognitive (5 days/week) and physical activities (7 days/week) combined with a set of devices for the measurement and monitoring from remote of vital and physical health parameters. The TAU equally lasts 6 weeks and includes paper and pencil cognitive activities (5 days/week), with clinician's prescription to perform physical exercise every day and to monitor selected vital parameters. DISCUSSION: Results of this study will inform on the efficacy of a technology-enhanced home care service to preserve cognitive and motor levels of functioning in MCI and AD, in order to slow down their loss of autonomy in daily life. The expected outcome is to ensure the continuity of care from clinical practice to the patient's home, enabling also cost effectiveness and the empowerment of patient and caregiver in the care process, positively impacting on their quality of life. TRIAL REGISTRATION: ClinicalTrials.gov ID: NCT02746484 (registration date: 12/apr/2016 - retrospectively registered).

A prospective study of the effects of carbocysteine lysine salt on frequency of exacerbations in COPD patients treated with or without inhaled steroids.

OBJECTIVE: COPD is one of the major causes of morbidity and mortality worldwide and represents one of the most important issues for public health. Frequent exacerbations induce a faster decline in lung function and poorer quality of life, increase mortality, and have a socio-economic impact with a high burden in terms of resources and healthcare costs. The clinical trials evaluated the effect of mucolytics in COPD and showed that the long-term carbocysteine, associated with bronchodilators, anticholinergics, and steroids, reduces the frequency of exacerbations and improves the quality of life. PATIENTS AND METHODS: The aim of this prospective real-life study was to evaluate the long-term impact on exacerbations (at 1 year) in COPD patients treated with carbocysteine lysine salt (single dose of 2.7 g once a day) in addition to background therapy with or without inhaled steroids. RESULTS: In a total of 155 evaluable patients, our study showed that the addition of a single dose of carbocysteine lysine salt to background therapy determines a statistically significant reduction of the average number of exacerbations vs. the number observed in the previous year (from 1.97±0.10 to 1.03±0.11; p<0.01), irrespective of treatment with or without inhaled steroids. In particular, in patients with ≥2 exacerbations in the previous year, the addition of carbocysteine lysine salt resulted in a statistically significant reduction in the exacerbations rate from 69% to 33% and from 58% to 25%, respectively (p<0.01) in patients with or without inhaled steroids. CONCLUSIONS: In summary, our data highlighted the efficacy of long-term administration of a single daily dose of carbocysteine lysine salt (2.7 g/day) in reducing the number and rate of exacerbations in COPD patients, independently from the use of inhaled steroids.

Carbocysteine counteracts the effects of cigarette smoke on cell growth and on the SIRT1/FoxO3 axis in bronchial epithelial cells.

BACKGROUND: Cigarette smoke may accelerate cellular senescence by increasing oxidative stress. Altered proliferation and altered expression of anti-aging factors, including SIRT1 and FoxO3, characterise cellular senescence. The effects of carbocysteine on the SIRT1/FoxO3 axis and on downstream molecular mechanisms in human bronchial epithelial cells exposed to cigarette smoke are largely unknown. AIMS: Aim of this study was to explore whether carbocysteine modulated SIRT1/FoxO3 axis, and downstream molecular mechanisms associated to cellular senescence, in a bronchial epithelial cell line (16-HBE) exposed to cigarette smoke. METHODS: 16HBE cells were stimulated with/without cigarette smoke extracts (CSE) and carbocysteine. Flow cytometry and clonogenic assay were used to assess cell proliferation; western blot analysis was used for assessing nuclear expression of SIRT1 and FoxO3. The nuclear co-localization of SIRT1 and FoxO3 was assessed by fluorescence microscopy. Beta galactosidase (a senescence marker) and SIRT1 activity were assessed by specific staining and colorimetric assays, respectively. ChiP Assay and flow cytometry were used for assessing survivin gene regulation and protein expression, respectively. RESULTS: CSE decreased cell proliferation, the nuclear expression of SIRT1 and FoxO3 and increased beta galactosidase staining. CSE, reduced SIRT1 activity and FoxO3 localization on survivin promoter thus increasing survivin expression. In CSE stimulated bronchial epithelial cells carbocysteine reverted these phenomena by increasing cell proliferation, and SIRT1 and FoxO3 nuclear expression, and by reducing beta galactosidase staining and survivin expression. CONCLUSIONS: The study shows for the first time that carbocysteine may revert some senescence processes induced by oxidative stress due to cigarette smoke exposure.

Mechanical and metabolic profile of locomotion in adults with childhood-onset GH deficiency.

OBJECTIVE: The aim of the present study was to evaluate the energy cost and the mechanical work of locomotion in a group of adults with childhood-onset GH deficiency (GHD). SUBJECTS: Eight males with childhood-onset GHD (mean age+/-s.d.: 31.7+/-3.6 years; mean height: 145.1+/-6.7cm) and six age-, sex- and exercise-matched normal subjects were studied. DESIGN: GHD patients and healthy controls were requested to walk and run in the speed range of 2-11km h(-1). For each condition, simultaneous mechanical and metabolic measurements were taken. METHODS: Oxygen consumption, and mechanical internal and external work of locomotion were evaluated with standard open-circuit respirometry and three-dimensional motion analysis respectively. RESULTS: External work was not significantly different between GHD patients and healthy controls, while internal work was higher for patients at all speeds. In walking, the relationships between both the mechanical energy recovery and the metabolic cost with speed were shifted towards lower speeds in patients. As a consequence, the optimal speed of walking, i.e. the speed at which the cost of locomotion is minimum, was lower for GHD patients. Stride frequency was significantly higher (11.2-11.3%) for GHD patients at all speeds of walking and running. GHD patients were unable to run at speeds higher than 8km h(-1) for the time needed to reach a metabolic steady state. CONCLUSION: It appears that both the mechanics and energetics of locomotion in short-statured adults with childhood-onset GHD are not strikingly different from those of healthy controls, thus demonstrating a substantial 'normality' in this group of GHD patients at metabolically attainable speeds. The 'harmonic' body structure and the adherence to allometric transformations in these patients do not exclude the possibility of a different metabolic role of GH in normally statured adults with childhood-onset GHD and in those with acquired GHD, taking into account the well recognized heterogeneity of the adult GHD syndrome.

Effects of stride frequency on mechanical power and energy expenditure of walking.

The energetics and mechanics of walking were investigated at different speeds, both at the freely chosen stride frequency (FCSF) and at imposed ones (up to +/- 40% of FCSF). Metabolic energy expenditure was minimized at FCSF for each speed. Motion analysis allowed to calculate: the mechanical internal work rate (Wint), needed to move the segments with respect to the body center of mass (bcm); the external work rate (Wext), necessary to move bcm in the environment; and the total work rate (Wtot), equal to Wint+Wext. Wtot explains the metabolic optimization only at high speeds, while Wext, differently from previously reported, displays minima which better predict FCSF at all speeds (exception made for 1.39 m.s-1). This is probably caused by an overestimation of Wint due to a more ballistic movement of the limbs at low speeds (and low frequencies). The tendency of Wext to increase at high frequencies is due to a persistent minimal vertical excursion of bcm (about 0.02 m, the "locomotory dead space"). While the match between mechanics and energetics (at FCSF and imposed frequencies) occurs to a certain extent, it could be improved by removing the methodological assumptions about the energy transfer between segments and by the possibility to account for the coactivation of antagonist muscles.

The mechanisms for minimizing energy expenditure in human locomotion.

In walking and in running the progression of the body involves at each step changes in kinetic energy, Ek, due to acceleration and deceleration, and changes of potential energy, Ep, due to vertical displacement. The energy costs of walking and running are minimized by two different mechanisms. In walking an alternate exchange of Ek and Ep takes place at each step, so that the muscles have only to restore the small part of the energy that is not recovered. The most economical speed of walking is that at which this recovery is maximal. In addition, at each speed there is an optimal frequency at which the total (external plus internal) mechanical power, and hence the metabolic cost, is minimal. In running the changes of Ek and Ep are almost completely in phase, implying a greater energy dissipation than in walking: part of this energy is stored by stretching the elastic elements of the previously contracted muscles and recovered during the following cycle, increasing the overall efficiency of the progression. The energy cost of walking with a load increases proportionally with the load. However, walking at low speed with a load not exceeding 5-10 per cent of the body weight is not more expensive than unloaded walking. Moreover, it has been observed that African women walking at their optimal speed can carry on their heads loads of up to 20 per cent of their body weight without any extra cost. A possible explanation of this finding could be that a different distribution of the body mass, with a higher position of the centre of gravity of the body, further increases the recovery of energy at each step.

Screening for breast cancer: report of a population-based experience in the city of Milan, Italy.

AIMS AND BACKGROUND: Mammographic screening is recommended as a current health practice. The aim of the present study is to report the results of a new program which started in the city of Milan in 1989. METHODS: A total of 4882 women aged 50 to 61 years and resident in quarter no. 16 of Milan were invited by mail to attend the screening at the San Paolo Hospital based on two-view mammography and physical examination. RESULTS: A total of 2953 (60.5%) women attended the first screening round, and 18 cancers were detected (1 Tis, 8 T1, 9 T2). The detection rate was 6.9 x 1000, and the prevalence/incidence ratio was around 3.5. CONCLUSIONS: The study confirms the feasibility of breast cancer screening in an urban setting by using the existing general hospital facilities and should be considered as a possible model for other urban experiences.

Maximal anaerobic (lactic) capacity and power of the horse.

Blood lactate concentrations were determined in 16 horses (three Thoroughbreds, seven Standardbreds and six polo ponies) before and 5 mins after they galloped over distances of 200, 300 and 400 m at maximal speed. The highest net lactate concentration (delta Lamax) of 14 to 15 mmol/litre was attained by the polo ponies and the highest speed by the Thoroughbreds. The maximal rate of lactate production (delta Låmax) was about 35 mmol/litre X min for the polo ponies and 20 to 25 mmol/litre X min for the Standardbreds and the Thoroughbreds. Values for delta Lamax and delta Låmax were similar to those measured in human athletes after exhaustive work. delta Låmax increases with the speed (v) and can be described by the equation delta Lå = a (v-v1), where a is a proportionality constant representing the amount of lactate needed to cover a unit distance and v1 the theoretical speed at which delta Lå = 0 X v1 was highest for the Thoroughbreds and lowest for the polo ponies; this difference could be caused by the effect of training and/or to genetic differences among the different breeds of horses X v1 could be a useful index of the fitness of a horse following a training programme.

[Clinical and mammographic screening in a district of Milan: organization, social influence and results]. / Screening clinico-mammografico in una circoscrizione di Milano: aspetti organizzativi, impatto sociale e risultati.

A reduction in the mortality rate for breast cancer in women over 50 years undergoing mammographic screening has been reported in many studies. Since the first experience in Florence in 1970, mammographic screenings on a population from different areas of Italy began. We report the experience carried out in the 16th District of Milan among women from 50 to 60 years of age. A promotional activity with the use of local media supported the program. The screening was based on two-view conventional mammography and clinical examination. Immediate response was given to the women. The compliance was 60%. Mainly immigrants, with only primary school education, mothers of several children and freelancers seem to be the main features of the women in the non-attenders group.

Muscle function and functional ability improves more in community-dwelling older women with a mixed-strength training programme.

BACKGROUND: Supervised training can reach a limited number of elderly people. OBJECTIVE: To determine the impact of a 1-year mixed-strength training programme on muscle function (MF), functional ability (FA) and physical activity (PA). SETTING: Twice-a-week hospital-based exercise classes and a once-a-week home session. PARTICIPANTS: twenty-eight healthy community-dwelling men and women on the training programme and 20 controls aged over 75 years. METHODS: Training with two multi-gym machines for the lower limbs at 60% of the repetition maximum (1RM). At-home subjects used elastic bands. MEASUREMENTS: Maximum isometric strength of knee extensors (KE), ankle plantar flexors (PF), leg extensor power (LEP), functional reach (FR), chair rise 1 (CR1) and 10 times (CR10), bed rise (BR), six-minute walking test (6MWT), stair climbing (SC), get-up-and-go (GU&G), one-leg standing (1LS). PA was assessed with the Paqap questionnaire. RESULTS: Women were significantly weaker than men at baseline: -47% for KE and -59% for PF. Training induced significant gains in MF and FA in the training females; males improved significantly only in FA. PA levels increased non-significantly (2%) in all of the training group. CONCLUSIONS: Long-term mixed-strength programmes can improve MF and FA in elderly females, and FA in elderly males.

Ventilatory work during exercise at high altitude.

Oxygen consumption, ventilation, and dynamic respiratory work were measured in three male subjects during cycling at 122 and 3500 m above sea level (ASL). At a given ventilation the dynamic respiratory work was 20% less at 3500 m ASL; this change was due to a decrease of airway resistance. At a given submaximal exercise intensity, the respiratory work was significantly higher at 3500 m ASL (+ 140%-180%); hence, the increase of ventilation was not compensated for by the decrease of airway resistance. At VO2max the respiratory work was predicted to reach its maximal value at 5800 m ASL where it was 30% higher than at sea level.

Mechanical work rate minimization and freely chosen stride frequency of human walking: a mathematical model.

The interplay between the work done to move the body centre of mass with respect to the environment (external work) and the work done to move the limbs with respect to the body (internal work) has been shown experimentally partially to determine the freely chosen stride frequency during walking. A mathematical model that estimates the two components of the mechanical work is proposed. The model, according to the criterion of work rate minimization (both positive and positive plus negative), is able to predict the natural stride frequency as a function of the average progression speed. The adequacy of the model and the validity of the assumptions have been checked against measurements of natural stride frequency in 11 subjects walking on a treadmill at several speeds (range 1-3 m s-1). Comparison with theoretical predictions shows good agreement with the minimization of positive work rate at low speeds, while at high speeds the stride frequency is better explained by the model for minimum positive plus negative work rate.

Work tolerance and physiological responses to thermal environment wearing protective NBC clothing.

Six young, healthy male subjects performed a series of experiments in a climatic chamber in different environmental conditions wearing protective ventilated NBC clothing. Ambient temperature, TA, ranged from -20 to 35 degrees C, relative humidity, RH, from 20 to 85%, and air velocity, VA, from 0 center dot 1 to 5 center dot 0 ms-1. In addition, thermal radiation, measured by the temperature of the globothermometer, TG, was artificially increased in some experiments. A total of 32 experiments were performed. The subject had to exercise on a bicycle ergometer at a mechanical power of 60 W for 120 min. Heart rate, HR, oxygen uptake, VO2, skin temperature, Tsk, and rectal temperature, Tre, were measured during the experiments together with the temperature of the space between skin and garment, Tmu. Sweat loss was determined as the difference of the body weight before and after the experiment. Tmu was well correlated with the chamber environmental parameters. During heat exposure work duration began to decrease progressively from a Tmu > 30 degrees C, reducing to 40 min at the highest thermal load. About the same value of Tmu marked the departure of HR, VO2, Tsk and Tre from the values measured during the same work load in neutral conditions. Also, during cold exposure at -20 degrees C work duration was reduced below 1 h, but the limit appeared to be the cold at the extremities. From these findings it appears that Tmu is a good indicator of the thermal load and is related to the environmental condition by the equation: Tmu = 9 center dot 93 + 0 center dot 56 TA + 0 center dot 023 TG + 0 center dot 14 RH (T in degrees C, RH in %). For better comfort and performance Tmu should be monitored whenever a subject has to work wearing an NBC garment and the ventilating system must be adequate to fulfil the needs imposed on the subject by an adverse environment, in particular a high relative humidity.

Mechanical determinants of gradient walking energetics in man.

1. The metabolic cost and the mechanical work at different speeds during uphill, level and downhill walking have been measured in four subjects. 2. The mechanical work has been partitioned into the internal work (W(int)), due to the speed changes of body segment with respect to the body centre of mass (BCM), and the external work (W(ext)), related to the position and speed changes of the BCM in the environment. 3. W(ext) has been further divided into a positive part W+ext) and a negative one (W-(ext)), associated with the energy increases and decreases, respectively, over the stride period. 4. For all constant speeds the most economical gradient has been found to be -10.2% (+/- 0.8 S.D.). 5. At each gradient there is a unique W+ext/W-ext ratio (= 1 in level walking), regardless of speed, with a tendency for W-ext and W+ext to vanish above +15% and below -15% gradient, respectively. 6. W(int) is constant at each speed regardless of gradient. This is partly explained by an only slight decrease in stride frequency at increasing gradient. W(int) constancy implies that it has no role in determining the optimum gradient. 7. A linear multiple regression relating W+ext and W-ext to the metabolic cost at different gradients showed that negative (eff-) and positive (eff+) efficiencies decrease with increasing speed (from 0.912 to 0.726, and from 0.182 to 0.146, respectively). The eff-/eff+ ratio, however, remains rather constant (4.995 +/- 0.125 S.D.). 8. We conclude that the measured W(ext), the W+ext/W-ext partitioning and eff-/eff+ ratio, i.e. the different efficiency of the muscles used as force and brake generators, can explain the metabolic optimum gradient at about -10%.

The transition between walking and running in humans: metabolic and mechanical aspects at different gradients.

Five subjects walked and ran at overlapping speeds and different gradients on a motorized treadmill. At each gradient the speed was obtained at which walking and running have the same metabolic cost (Sm) and the speed of spontaneous (Ss) transition between the two gaits was measured. Ss was found to be statistically lower than Sm at all gradients, the difference being in the range of 0.5-0.9 km h-1. The motion analysis of walking reveals that at all gradients and at increasing speed: (1) the percentage of recovery, an index of mechanical energy saving related to the pendulum-like characteristic of walking, decreases; (2) the lower limb spread reaches a limit in walking; and consequently (3) both the stride frequency and the internal mechanical work, due to limb acceleration in relation to the body centre of mass, increase much more in walking than in running. Switching to a run, although implying a higher frequency, makes the internal work decrease as a result of the lower limb spread. In this paper several influences, such as the 'ratings of perceived exertion' (RPE), on the choice of beginning to run when it is more economical to walk, are discussed. A tentative hypothesis on the determinants of Ss, which is emphasized to be a speed which has to be studied in detail but is generally avoided in locomotion, is based on a comfort criterion from peripheric afferences and is reflected by the fact that at Ss a running stride costs as much as a walking stride.(ABSTRACT TRUNCATED AT 250 WORDS)

Mechanical determinants of the minimum energy cost of gradient running in humans.

The metabolic cost and the mechanical work of running at different speeds and gradients were measured on five human subjects. The mechanical work was partitioned into the internal work (Wint) due to the speed changes of body segments with respect to the body centre of mass and the external work (Wext) due to the position and speed changes of the body centre of mass in the environment. Wext was further divided into a positive part (W+ext) and a negative part (W-ext), associated with the energy increases and decreases, respectively, over the stride period. For all constant speeds, the most economical gradient was -10.6 +/-0.5% (S.D., N = 5) with a metabolic cost of 146.8 +/- 3.8 ml O2 kg-1 km-1. At each gradient, there was a unique W+ext/W-ext ratio (which was 1 in level running), irrespective of speed, with a tendency for W-ext and W+ext to disappear above a gradient of +30% and below a gradient of -30%, respectively. Wint was constant within each speed from a gradient of -15% to level running. This was the result of a nearly constant stride frequency at all negative gradients. The constancy of Wint within this gradient range implies that Wint has no role in determining the optimum gradient. The metabolic cost C was predicted from the mechanical experimental data according to the following equation: [formula: see text] where eff- (0.80), eff+ (0.18) and effi (0.30) are the efficiencies of W-ext, W+ext and Wint, respectively, and el- and el+ represent the amounts of stored and released elastic energy, which are assumed to be 55J step-1. The predicted C versus gradient curve coincides with the curve obtained from metabolic measurements. We conclude that W+ext/W-ext partitioning and the eff+/eff- ratio, i.e. the different efficiency of the muscles during acceleration and braking, explain the metabolic optimum gradient for running of about -10%.

Work of breathing in dog during exercise.

In six dogs trained to wear a mask and to swallow an esophageal balloon, the dynamic work of breathing (Wdyn) was measured while the animals ran on a treadmill at different intensities (7-13 km.h-1,+10%). Wydn (kg.m.min-1) increased with ventilation (VE, 1.min-1) according to Wdyn = 0.308.10(-2) VE2 + 0.0098.10(-2).VE3. However, if the exercise was prolonged so that the body temperature rose above approximately 39 degrees C, Wdyn, for a given ventilation, decreased; and hence Wdyn = 0.253.10(-2).VE2 -- 0.0011.10(-2).VE3. Similar observations have been made on another dog heated from an external source. From this finding it seems that during exercise, when the temperature rises and the ventilation increases to dissipate heat, the airway size, at least in some portion of the respiratory tract, increases markedly and therefore the cost of breathing is greatly diminished. This mechanism would save oxygen for the exercising limb muscles when exercise has to be continued for an extended time.