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C Capelli

Publications and source records attributed to C Capelli.

65 records · Page 4Linked to original sources
PubMed1991

The energy cost of running increases with the distance covered.

The net energy cost of running per unit of body mass and distance (Cr, ml O2.kg-1.km-1) was determined on ten amateur runners before and immediately after running 15, 32 or 42 km on an indoor track at a constant speed. The Cr was determined on a treadmill at the same speed and each run was performed twice. The average value of Cr, as determined before the runs, amounted to 174.9 ml O2.kg-1.km-1, SD 13.7. After 15 km, Cr was not significantly different, whereas it had increased significantly after 32 or 42 km, the increase ranging from 0.20 to 0.31 ml O2.kg-1.km-1 per km of distance (D). However, Cr before the runs decreased, albeit at a progressively smaller rate, with the number of trials (N), indicating an habituation effect (H) to treadmill running. The effects of D alone were determined assuming that Cr increased linearly with D, whereas H decreased exponentially with increasing N, i.e. Cr = Cr0 + a D + He-bN. The Cr0, the "true" energy cost of running in nonfatigued subjects accustomed to treadmill running, was assumed to be equal to the average value of Cr before the run for N equal to or greater than 7 (171.1 ml O2.kg-1.km-1, SD 12.7; n = 30).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Pedalling in space as a countermeasure to microgravity deconditioning.

A system consisting of two mechanically coupled counter rotating bicycles, moving on the inner wall of a cylindrical space module, is proposed to prevent microgravity deconditioning. The two pedalling subjects generate a centrifugal acceleration vector (ac) simulating gravity. This last depends on the peripheral velocity (v) and on the radius of gyration (R): ac = v2/R. Since R is constant and equal to the inner radius of the space module, any desired value of ac can be achieved by selecting the appropriate v value. The corresponding mechanical (w) and metabolic (VO2) powers can then be calculated on the basis of the biomechanical and anthropometric characteristics of the system and subjects. It is shown that if R = 2 m, in order to attain ac = 1 g at the feet, v = 4.5 m s-1, w = 60 W and VO2 = 1.2 litres min-1. However if R = 6 m, then v = 7.8 m s-1, w = 140 W and VO2 = 3 litres min-1. The average arterial pressures prevailing at the head and feet levels in the two above conditions can also be calculated as 95, 150 and 80, 170 mmHg, respectively for a mean arterial pressure of 100 mmHg at the aortic bulbus. In conclusion, by selecting appropriately the radial dimensions of the space module in order to minimize: (1) vestibular disturbances, (2) head to feet centrifugal acceleration gradients and (3) manufacturing costs, it may be possible to combine exercise and simulated gravity, with no need for additional external power.

Aerospace Medicine↗
PubMed1991

Maximal explosive power and aerobic exercise in humans.

The maximal explosive power (wmax), i.e. the mechanical power developed over short bursts (less than 5 s) of all-out cycling, or uphill running, in humans attains 12-17 W*kg-1 in non athletics subjects. Thus, in terms of O2 consumption wmax is about four times larger than the subjects VO2max. The peak instantaneous power during a vertical jump off both feet (w) in non athletic subjects is about 50-55 W kg-1 and attains 70-75 W*kg-1 in "power" athletes. Both wmax and w decrease when the all-out efforts is performed from a priming aerobic exercise: if the intensity of this last approaches VO2max, then wmax and w are reduced to about 75% the value attained from rest. Thus, in the course of high intensity efforts, an athlete can develop a still remarkable fraction of his maximal absolute power. The decrease mentioned above is proportional, and presumably causally related, to the decrease of the high energy phosphate concentration occurring in the muscle at the onset of the exercise, and maintained throughout the effort duration.

Humans↗
PubMed1990

Energy cost and efficiency of sculling a Venetian gondola.

Oxygen uptake was measured on four male subjects during sculling gondolas at constant speeds from approximately 1 to approximately 3 m.s-1. The number of scullers on board in the different trials was one, two or four. Tractional water resistance (drag, D, N) was also measured in the same range of speeds. Energy cost of locomotion per unit of distance (C, J.m-1), as calculated from the ratio of O2 uptake above resting to, increased with v according to a power function (C = 155.2.v1.67; r = 0.88). Also D could be described as a power function of the speed: D = 12.3.v2.21; r = 0.94). The overall efficiency of motion, as obtained from the ratio of D to C, increased with speed from 9.2% at 1.41 m.s-1 to 14.5% at 3.08 m.s-1. It is concluded that, in spite of this relatively low efficiency of motion, the gondola is a very economic means. Indeed, at low speeds (approximately 1 m.s-1), the absolute amount of energy for propelling a gondola is the same as that for waking on the level at the same speed for a subject of 70 kg body mass.

Adult↗
PubMed1987

Gravity-dependent distribution of parietal subpleural interstitial pressure.

Using liquid-filled catheters, we recorded, in 30 anesthetized, spontaneously breathing supine rabbits, the hydraulic pressure from the parietal subpleural interstitial space (Pspl). Through a small exposed area of parietal pleura a plastic catheter (1 mm ED), with a closed and smooth tip and several holes on the last centimeter, was carefully advanced between the muscular layer and the parietal pleura, tangentially to the pleural surface to reach the submesothelial layer. Simultaneous measurements of pleural liquid pressure (Pliq) were obtained from intrapleurally placed cannulas. End-expiratory Pspl decreased (became more negative) with increasing height (LH) according to the following: Pspl (cmH2O) = -1 - 0.4 LH (cm), the corresponding equation for Pliq being Pliq (cmH2O) = -1.5 - 0.7 LH (cm). Thus at end expiration a transpleural hydraulic pressure difference (Pliq-Pspl) developed at any height, increasing from the bottom to the top of the cavity as Pliq - Pspl (cmH2O) = -0.5 - 0.3 LH (cm). The Pliq-Pspl difference increased during inspiration due to the much smaller tidal change in Pspl than in Pliq. By considering the gravity-dependent distribution of the functional hydrostatic pressure in the systemic capillaries of the pleura (Pc) and the Pspl and Pliq values integrated over the respiratory cycle we estimated that on the average, the Pc-Pspl difference is sevenfold larger than the Pspl-Pliq difference.

Animals↗
PubMedDate not supplied

Energetics of kayaking at submaximal and maximal speeds.

The energy cost of kayaking per unit distance (C(k), kJ x m(-1)) was assessed in eight middle- to high-class athletes (three males and five females; 45-76 kg body mass; 1.50-1.88 m height; 15-32 years of age) at submaximal and maximal speeds. At submaximal speeds, C(k) was measured by dividing the steady-state oxygen consumption (VO(2), l x s(-1)) by the speed (v, m x s(-1)), assuming an energy equivalent of 20.9 kJ x l O(-1)(2). At maximal speeds, C(k) was calculated from the ratio of the total metabolic energy expenditure (E, kJ) to the distance (d, m). E was assumed to be the sum of three terms, as originally proposed by Wilkie (1980): E = AnS + alphaVO(2max) x t-alphaVO(2max) x tau(1-e(-t x tau(-1))), were alpha is the energy equivalent of O(2) (20.9 kJ x l O(2)(-1)), tau is the time constant with which VO(2max) is attained at the onset of exercise at the muscular level, AnS is the amount of energy derived from anaerobic energy utilization, t is the performance time, and VO(2max) is the net maximal VO(2). Individual VO(2max) was obtained from the VO(2) measured during the last minute of the 1000-m or 2000-m maximal run. The average metabolic power output (E, kW) amounted to 141% and 102% of the individual maximal aerobic power (VO(2max)) from the shortest (250 m) to the longest (2000 m) distance, respectively. The average (SD) power provided by oxidative processes increased with the distance covered [from 0.64 (0.14) kW at 250 m to 1.02 (0.31) kW at 2000 m], whereas that provided by anaerobic sources showed the opposite trend. The net C(k) was a continuous power function of the speed over the entire range of velocities from 2.88 to 4.45 m x s(-1): C(k) = 0.02 x v(2.26) (r = 0.937, n = 32).

Adolescent↗
PubMedDate not supplied

Effects of microgravity on muscular explosive power of the lower limbs in humans.

The maximal explosive power of the lower limbs of one astronaut has been measured before launch, and 2, 6 and 11 days after re-entry from 31 days on the MIR Station (EUROMIR '94). The subject, sitting on the carriage-seat of a Multipurpose Ergometer-Dynamometer (MED) constructed ad hoc in our laboratory, pushed maximally with both feet on two force platforms (knees angle 110 degrees). The carriage was free to move backwards on two rails inclined 20 degrees upwards. The force (F) of the lower limbs and the speed of the carriage (v) were recorded and the instantaneous mechanical power (w) was calculated as w = F * v. The average value of the mechanical power (w max) throughout the explosive effort was then obtained. The overall duration of the push was on the average about 0.3 s. It was observed that, at day R+2, mean force, maximal velocity, maximal power (mean and peak), maximal acceleration and overall mechanical work, were all reduced between 60 and 80% of pre-flight values. However, the recovery was remarkably fast, since all these parameters attained about 90% of pre-flight values by day R+11.

Biomechanical Phenomena↗
PubMedDate not supplied

Asymptomatic hepatitis G virus infection in blood donors.

BACKGROUND: Hepatitis G virus (HGV) has been reported in patients with fulminant hepatitis and aplastic anemia, but HGV RNA has also been found in healthy individuals. The possible associations of HGV with liver function and hematologic abnormalities in asymptomatic blood donors were investigated. STUDY DESIGN AND METHODS: Serum HGV RNA was determined in 200 repeat donors (Group A), 44 subjects with elevated alanine aminotransferase (Group B), and 54 hepatitis C virus carriers (Group C). Liver histology was evaluated in Group C by using the histologic activity index. RESULTS: HGV RNA was detected in three subjects of Group A (1.5%; 95% CI: 0.3-4.3), two of Group B (4.5%; 95% CI: 0.6-15.5%), and six of Group C (11.1%; 95% CI: 4.2-22.6). The prevalence of leukopenia and elevated gamma-glutamyl transpeptidase was higher in the 11 viremic donors than in 88 nonviremic subjects (36% vs. 2.3%, and 55% vs. 22%, respectively; p < 0.05), matched for clinical and demographic characteristics. The mean histologic activity index score +/- standard error was 4 +/- 0.7 in the HGV RNA-positive donors and 3.4 +/- 0.3 in the HGV RNA-negative donors. CONCLUSION: HGV is endemic in Italian blood donors, although it has a limited role in causing liver damage. Further studies are needed to clarify its role in inducing transfusion-associated disease in myelosuppression.

Adult↗