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Biomedical subjects

F Saibene

Publications and source records attributed to F Saibene.

At least 19 recordsLinked to original sources
PubMed2005

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.

Activities of Daily Living↗
PubMed2003

The optimal locomotion on gradients: walking, running or cycling?

On level ground, cycling is more economical than running, which in turn is more economical than walking in the high speed range. This paper investigates whether this ranking still holds when moving on a gradient, where the three modes are expected to be mainly facing the same burden, i.e. to counter gravity. By using data from the literature we have built a theoretical framework to predict the optimal mode as a function of the gradient. Cycling was found to be the mode of choice only below 10-15% gradient, while above it walking was the least expensive locomotion type. Seven amateur bikers were then asked to walk, run and ride on a treadmill at different gradients. The speed was set so as to maintain almost constant the metabolic demand across the different gradients. The results indicate that the "critical slope", i.e. the one above which walking is less expensive than cycling (and running), is about 13-15%. One subject was loaded during bipedal gaits with a bicycle-equivalent mass, to simulate to cross-country cycling situation. The critical slope was close to 20%, due to the higher metabolic cost of loaded walking and running. Part of the findings can be explained by the mechanically different paradigms of the three locomotion types.

Adult↗
PubMed2000

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.

Adult↗
PubMed1999

The relationship between mechanical work and energy expenditure of locomotion in horses.

Three-dimensional motion capture and metabolic assessment were performed on four standardbred horses while walking, trotting and galloping on a motorized treadmill at different speeds. The mechanical work was partitioned into the internal work (W(INT)), due to the speed changes of body segments with respect to the body centre of mass, and the external work (W(EXT)), due to the position and speed changes of the body centre of mass with respect to the environment. The estimated total mechanical work (W(TOT)=W(INT)+W(EXT)) increased with speed, while metabolic work (C) remained rather constant. As a consequence, the 'apparent efficiency' (eff(APP)=W(TOT)/C) increased from 10 % (walking) to over 100 % (galloping), setting the highest value to date for terrestrial locomotion. The contribution of elastic structures in the horse's limbs was evaluated by calculating the elastic energy stored and released during a single bounce (W(EL,BOUNCE)), which was approximately 1.23 J kg(-)(1) for trotting and up to 6 J kg(-)(1) for galloping. When taking into account the elastic energy stored by the spine bending and released as W(INT), as suggested in the literature for galloping, W(EL,BOUNCE) was reduced by 0.88 J kg(-)(1). Indirect evidence indicates that force, in addition to mechanical work, is also a determinant of the metabolic energy expenditure in horse locomotion.

Animals↗
PubMed1999

Laryngeal movements during the respiratory cycle measured with an endoscopic imaging technique in the conscious horse at rest.

A video-laryngoscopic method, implemented with an algorithm for the correction of the deformation inherent in the endoscope optical system, has been used to measure the dorsoventral diameter (Drg) and the cross-sectional area (CSArg) of the rima glottidis in five healthy workhorses during conscious breathing at rest. Simultaneous recording of the respiratory airflow was also obtained in two horses. Drg measured 82.7 +/- 4.5 mm (mean +/- S.D.) independently of the respiratory phase, and did not differ from the measurement in post-mortem anatomical specimens of the same horses. CSArg ranged from 1130 +/- 117 mm2 (mean +/- S.D.) during the inspiratory phase to 640 +/- 242 mm2 during the expiratory phase; being always narrower than tracheal cross-sectional area, which was 1616 +/- 224 mm2, as determined from anatomical specimens. Both inspiratory and expiratory airflow waves displayed a biphasic pattern. Maximal laryngeal opening occurred in phase with the second inspiratory peak, while during expiration CSArg attained a minimum value during the first expiratory peak which was significantly smaller (P < 0.01) than the area subsequently maintained during the rest of the expiratiory phase. These quantitative measurements of equine laryngeal movements substantiate the important role played by the larynx in regulating upper airway respiratory resistance and the expiratory airflow pattern at rest.

Algorithms↗
PubMed1996

Respiratory mechanics during exhaustive submaximal exercise at high altitude in healthy humans.

1. The present investigation was conducted to test the hypothesis that the respiratory system is stressed more during exhaustive exercise in chronic hypoxia than in normoxia. 2. Four healthy male subjects (aged 33-35 years) exercised on a cycle ergometer at 75% of the local maximum oxygen consumption (Vo2,max) until exhaustion, at sea level (SL) and after a 1 month stay at 5050 m (HA). 3. Airflow at the mouth (V), oesophageal (Po) and gastric (Pg) pressures were measured at rest, during exercise and recovery. Minute ventilation (VE), respiratory power (Wresp), respiratory frequency (f) and transdiaphragmatic pressure (Pdi) were calculated from the measured variables. 4. The subjects' mechanical power output of cycling at HA was 23.7% lower than at SL. In spite of this reduction, time to exhaustion at HA was 55.3% less than at SL. VE increased slightly during exercise at SL, but showed a marked increase at HA, and at the end of exercise at HA was 47.3% higher than at SL. 5. Respiratory power increased more at HA than at SL (77.3% higher at the end of exercise) due to the increase in f needed to sustain the high VE. 6. Gastric pressure swings were negative at the end of HA exercise but always positive at SL. The Pai:Po ratio reached values below 1 at HA but never at SL. 7. These data seem to indicate that the respiratory system is stressed more during submaximal exercise at HA than at SL. We suggest that the exceedingly high VE demand, requiring an excessive Wresp, may lead to fatigue of the diaphragm.

Adult↗
PubMed1996

The effects of locomotor-respiratory coupling on the pattern of breathing in horses.

1. To investigate the effect of locomotor activity on the pattern of breathing in quadrupeds, ventilatory response was studied in four healthy horses during horizontal and inclined (7%) treadmill exercise at different velocities (1.4-6.9 m s(-1)) and during chemical stimulation with a rebreathing method. Stride frequency (f(s)) and locomotor-respiratory coupling (LRC) were also simultaneously determined by means of video recordings synchronized with respiratory events. 2. Tidal volume (V(T)) was positively correlated with pulmonary ventilation (V(E)) but significantly different linear regression equations were found between the experimental conditions (P < 0.0001), since the chemical hyperventilation was mainly due to increases in V(T), whereas the major contribution to exercise hyperpnoea came from changes in respiratory frequency (f(R)). 3. The average f(R) at each exercise level was not significantly different from f(S), although there was not always a tight 1:1 LRC. At constant speeds, f(S) was independent of the treadmill slope and hence the greater V(E) during inclined exercise was due to increased V(T). 4. At any ventilatory level, the differences in breathing patterns between locomotion and rebreathing or locomotion at different slopes derived from different set points of the inspiratory off-switch mechanism. 5. The percentage of single breaths entrained with locomotor rhythm rose progressively and significantly with treadmill speed (P < 0.0001) up to a 1:1 LRC and was significantly affected by treadmill slope (P < 0.001). 6. A LRC of 1:1 was systematically observed at canter (10 out of 10 trials) and sometimes at trot (5 out of 14) and it entailed (i) a 4- to 5-fold reduction in both V(T) and f(R) variability, and (ii) a gait-specific phase locking of inspiratory onset during the locomotor cycle. 7. It is concluded that different patterns of breathing are employed during locomotion and rebreathing due to the interference between locomotor and respiratory functions, which may play a role in the optimization and control of exercise ventilation in horses.

Animals↗
PubMed1996

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.

Adult↗
PubMed1995

Metabolic and mechanical aspects of foot landing type, forefoot and rearfoot strike, in human running.

The study was undertaken to assess the metabolic and the mechanical aspects of two different foot strike patterns in running, i.e. forefoot and rearfoot striking (FFS and RFS), and to understand whether there is some advantage for a runner to use one or the other of the two landing styles. Eight subjects performed two series of runs (FFS and RFS) on a treadmill at an average speed of 2.50, 2.78, 3.06, 3.33, 3.61, 3.89, 4.17 m s-1. Step frequency, oxygen uptake, mechanical work, and its two components, external and internal, were measured. No differences were found for step frequency, mechanical internal work per unit time and oxygen uptake, while external and total mechanical work per unit time were significantly higher, 7-12%, for FFS. The higher external work was the result of an increase of the work performed against both gravitational and inertial forces. As the energy expenditure was the same it has been speculated that a higher storage and release of energy takes place in the elastic structures of the lower leg with FFS. In a different series of experiments on six subjects contact time, time of deceleration and time of acceleration were measured by means of a video camera while running on the treadmill at 2.50, 3.33 and 4.17 m s-1, both FFS and RFS. Time of deceleration is similar for FFS and RFS, but contact time and time of acceleration are shorter, respectively 12 and 25%, for FFS.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

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.

Adult↗
PubMed1994

Pygmy locomotion.

The hypothesis that Pygmies may differ from Caucasians in some aspects of the mechanics of locomotion was tested. A total of 13 Pygmies and 7 Caucasians were asked to walk and run on a treadmill at 4-12 km.h-1. Simultaneous metabolic measurements and three-dimensional motion analysis were performed allowing the energy expenditure and the mechanical external and internal work to be calculated. In Pygmies the metabolic energy cost was higher during walking at all speeds (P < 0.05), but tended to be lower during running (NS). The stride frequency and the internal mechanical work were higher for Pygmies at all walking (P < 0.05) and running (NS) speeds although the external mechanical work was similar. The total mechanical work for Pygmies was higher during walking (P < 0.05), but not during running and the efficiency of locomotion was similar in all subjects and speeds. The higher cost of walking in Pygmies is consistent with the allometric prediction for smaller subjects. The major determinants of the higher cost of walking was the difference in stride frequency (+9.45, SD 0.44% for Pygmies), which affected the mechanical internal work. This explains the observed higher total mechanical work of walking in Pygmies, even when the external component was the same. Most of the differences between Pygmies and Caucasians, observed during walking, tended to disappear when the speed was normalized as the Froude number. However, this was not the case for running. Thus, whereas the tested hypothesis must be rejected for walking, the data from running, do indeed suggest that Pygmies may differ in some aspects of the mechanics of locomotion.

Adult↗
PubMed1994

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)

Adult↗
PubMed1994

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%.

Adult↗
PubMed1993

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.

Aged↗
PubMed1993

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%.

Adult↗
PubMed1993

[Clinical and mammographic screening in a district of Milan: organization, social influence and results].

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.

Breast Neoplasms↗
PubMed1992

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.

Biomechanical Phenomena↗