PubMed Health⌕ Search

Biomedical subjects

V J Caiozzo

Publications and source records attributed to V J Caiozzo.

53 records · Page 3Linked to original sources
PubMed1987

Effect of high-intensity exercise on the VE-VCO2 relationship.

The intrinsic relationship between ventilation (VE) and carbon dioxide output (VCO2) is described by the modified alveolar ventilation equation VE = VCO2 k/PaCO2(1-VD/VT) where PaCO2 is the partial pressure of CO2 in the arterial blood and VD/VT is the dead space fraction of the tidal volume. Previous investigators have reported that high-intensity exercise uncouples VE from VCO2; however, they did not measure the PaCO2 and VD/VT components of the overall relationship. In an attempt to provide a more complete analysis of the effects of high-intensity exercise on the VE-VCO2 relationship, we undertook an investigation where five subjects volunteered to perform three steady-state tests (SS1, SS2, SS3) at 60 W. One week after SS1 each subject was required to perform repeated 1-min bouts of exercise corresponding to a work rate of approximately 140% of maximal oxygen uptake (VO2max). Two and 24 h later the subjects performed SS2 and SS3, respectively. This exercise intervention caused PaCO2 during SS2 and SS3 to be regulated (P less than 0.01) approximately 4 Torr below the control (SS1) value of 38.8 Torr. Additionally, significant alterations were noted for VCO2 with corresponding values of 1.15 (SS1), 1.10 (SS2), and 1.04 (SS3) l/min. No changes were noted in either VD/VT or VE. In summary, it seems reasonable to suggest that the disproportionate increase in VE with respect to VCO2 noted in earlier work does not reflect an uncoupling. Rather the slope of the VE-VCO2 relationship is increased in a predictable manner as described by the modified alveolar ventilation equation.

Carbon Dioxide↗
PubMed1986

The effect of athletic clothing aerodynamics upon running speed.

The purpose of this study was to determine the effect of the wind resistance of athletic clothing upon running speed in sprinting and in distance running. Wind tunnel tests of clothing materials, hair, and shoes show that it is possible to lower the wind resistance of a runner from about 0.5% to over 6% by improved aerodynamics. Mathematical models of sprinting and distance running are developed to predict the effect of lower wind resistance upon race times. By lowering the wind resistance of a runner 2%, the models predict the effect of lower wind resistance upon race times. By lowering the wind resistance of a runner 2%, the models predict time savings from 0.01 s in the 100-m dash to 5.7 s in the marathon. This is the equivalent of lead distances of about 0.1 to 31 m. The sprint model may be used to predict the effect of altitude upon running speed. At the altitude of Mexico City, the model predicts an improvement of 0.08 s in 100 m and 0.16 s in 200 m. This is conservative compared to actual time savings. The results show that it is possible to lower the wind resistance significantly by improving clothing or by trimming or covering the hair, and that a small aerodynamic drag reduction can result in a significant performance increase.

Air Movements↗
PubMed1985

A comparison of the effect of external loading upon power output in stair climbing and running up a ramp.

Previous studies have shown that external loading increases the power output measured during stair climbing. However, it was noted in an earlier study that stairtreads form mechanical contraints which limit the extent to which a subject can be externally loaded, and, thereby, make it impossible to observe maximal power output for this type of activity. The purpose of this study was to compare the effects of external loading upon power output when running up stairs or a ramp. Since a ramp is free of the mechanical constraints of stairtreads, it was felt that higher power output values would be achieved using the ramp, and that it would be possible to observe an asymptote in power output which could not be obtained for stair climbing. Seven male subjects performed maximal ramp and stair climbing tests under five experimental loading conditions (no external load, 10.1, 19.2, 24.2, and 29.2 kg). For the ramp, it was possible to employ a sixth loading condition of 34.2 kg. For stair climbing, the mean (+/- SD) power output values under the five experimental conditions were 16.6 +/- 0.7, 17.3 +/- 1.3, 18.5 +/- 1.0, 18.6 +/- 1.5, and 18.9 +/- 1.7 W X kg-1, respectively. In contrast, the mean (+/- SD) power output values observed while running up the ramp were 18.8 +/- 1.4, 19.9 +/- 1.6, 20.5 +/- 1.6, 20.1 +/- 2.1, 20.3 +/- 2.1, and 19.8 +/- 1.9 W X kg-1, respectively. At each experimental condition, the differences between the ramp and stairs was significant (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1983

Does the gas exchange anaerobic threshold occur at a fixed blood lactate concentration of 2 or 4 mM?

The anaerobic threshold (theta an) is defined as the VO2 at which blood lactate concentration [lactate] begins to systematically increase (lactate "break point") during incremental exercise. Numerous studies have shown that gas exchange break points at the anaerobic threshold correlate highly (r congruent to 0.90) with the lactate break point. Recently, it has been suggested that the anaerobic threshold occurs at a fixed [lactate] of 2 mM or 4 mM. We therefore compared the gas exchange theta an to the three lactate criteria (break point, 2 mM, and 4 mM) for theta an estimation. Fourteen subjects performed an incremental cycle ergometer test. Ventilation and gas exchange were computed every 30 s. During the same 30-s intervals, venous blood was sampled for [lactate]. Four criteria were used for theta an determination: (1) systematic increase in VE/VO2, without a concomitant increase in VE/VCO2; (2) lactate break point; (3) 2 mM [lactate]; and (4) 4 mM [lactate]. Relative to the gas exchange criterion (i.e., #1), theta an was higher by 44, 280, and 1028 ml X min-1 for the three lactate criteria, respectively; the last two being significantly different (P less than 0.05). Thus, the anaerobic threshold discerned from gas exchange or the lactate break point does not correspond with a fixed, absolute [lactate] of 2 mM or 4 mM.

Adult↗
PubMed1982

A comparison of gas exchange indices used to detect the anaerobic threshold.

This study was undertaken to determine which of four commonly used ventilatory or gas exchange indices provides the most accurate and reliable detection of the anaerobic threshold (AT). Sixteen subjects performed two cycle ergometer tests to volitional fatigue. After 4 min of unloaded cycling, the work rate was increased 20 W/min. Ventilatory and gas exchange measurements were made every 30 s throughout each test. During one of the two tests (randomly assigned), venous blood was also sampled every 30 s for subsequent determinations of blood lactate (HLa) concentration. Four ventilatory and gas exchange indices (VE, VCO2, R, VE/VO2) were used separately to detect the AT. The AT determined from systematic increases in HLa concentration was used as the criterion measure. AT values (means +/- SE) (VO2, l/min) using VE, VCO2, R, VE/VO2, and HLa were 1.79 +/- 0.11, 1.74 +/- 0.11, 1.58 +/- 0.06, 1.84 +/- 0.11, and 1.85 +/- 0.11 l/min, respectively. The highest correlation between a ventilatory or gas exchange AT and ATHLa (i.e., criterion measure) was found for VE/VO2 (r=0.93, P less than 0.001). The VE/VO2 also provided the highest test-retest correlation for detection of the AT (r = 0.93, P less than 0.001). Multiple correlational analyses did not significantly enhance detection of the AT. These results favor the use of VE/VO2 for noninvasive detection of the AT because it proved to be the most sensitive and reliable ventilatory or gas exchange index studied.

Adult↗
PubMed1981

Training-induced alterations of the in vivo force-velocity relationship of human muscle.

Seventeen male and female subjects (ages 20-38 yr) were tested pre- and posttraining for maximal knee extension torque at seven specific velocities (0, 0.84, 1.68, 2.51, 3.35, 4.19, and 5.03 rad . s-1) with an isokinetic dynamometer. Maximal knee extension torques were recorded at a specific joint angle (0.52 rad below the horizontal plane) for all test speeds. Subjects were randomly assigned to one of three experimental groups: group A, control, n = 7; group B, training at 1.68 rad . s-1, n = 5; or group C, training at 4.19 rad . s-1, n = 5. Subjects trained the knee extensors by performing two sets of 10 single maximal voluntary efforts three times a week for 4 wk. Before training, each training group exhibited a leveling-off of muscular tension in the slow velocity-high force region of the in vivo force-velocity relationship. Training at 1.68 rad . s-1 resulted in significant (P less than 0.05) improvements at all velocities except for 5.03 rad . s-1 and markedly affected the leveling-off in the slow velocity-high force region. Training at 4.19 rad . s-1 did not affect the leveling-off phenomenon but brought about significant improvements (P less than 0.05) at velocities of 2.51, 3.35, and 4.19 rad . s-1. The changes seen in the leveling-off phenomenon suggest that training at 1.68 rad . s-1 might have brought about an enhancement of motoneuron activation.

Adult↗
PubMed1980

The effect of external loading upon power output in stair climbing.

Previous studies have examined man's ability to produce external power output during maximal repetitive work cycles of short duration. It appears, however, that there were methodological limitations which would inherently mask man's true capacities. Consequently, we examined the effect of variable external loads upon external power output as measured by running upstairs. Fourteen male subjects (16-31 years of age) who regularly participated in competitive sports performed maximal stair step tests under five experimental loading conditions (no external load, 10.1, 19.2, 24.2, and 29.2 kg). Significant increases (P < 0.05) in external power output were found. External power output increased from a mean of 15.9 W x kg-1 +/- 1.0 (unloaded condition) to 18.5 W x kg-1 +/- 1.5 (external load of 29.2 kg). This is the first modern investigation demonstrating that external loads effect external power output as measured by this technique.

Adolescent↗
PubMedDate not supplied

Effects of short-term exposure to carbon monoxide in subjects with coronary artery disease.

Twenty-four male subjects with stable angina pectoris performed graded exercise tests after being exposed to either carbon monoxide (CO) or clean air in a randomized crossover double-blind experiment in which each subject acted as his own control. Subject's blood carboxyhemoglobin levels were increased from a baseline level of approximately 1.5% to 3% of saturation, post-CO exposure. Cardiographic and respiratory gas exchange data were obtained during the tests in which the subjects exercised to the point of onset of anginal pain. The goal of the study was to determine if low-level CO exposure compromised the ability of these individuals to perform work. Data were evaluated statistically using a two-factor analysis of variance with repeated measures; the factors were exposure ATMOSPHERE (clean air vs. CO) and ORDER of exposure (clean air first, CO second vs. CO first, clean air second). One-tailed tests were used, and differences were considered significant at the p less than .05 level. The time to onset of angina was reduced 6% (p = .046) after CO exposure relative to clean air. Oxygen uptake (VO2) at angina was reduced by approximately 3% (p = .04). A subgroup of individuals who exhibited depression in the ST segment of their electrocardiograph tracings showed a 12% reduction in time to onset of angina and a 20% reduction in the time to onset of 0.1 mV ST segment depression; both of these findings were also statistically significant.

Aged↗
PubMedDate not supplied

Contractile properties of slow and fast muscle following tourniquet ischemia.

Tourniquet application is commonly used during surgery on an extremity to create a bloodless field. Investigations have focused on the ultrastructural, histochemical, and biochemical effects of tourniquet ischemia on muscle. Few studies, however, have examined the influence of tourniquet ischemia on the contractile properties of muscle. The purpose of this study was not only to examine this latter consideration, but also to determine whether slow and fast muscles exhibit a differential response. In adult male guinea pigs, the plantaris and soleus muscles of control (N = 5) and experimental legs (N = 5) were tested for time-peak-tension (TPT), one-half relaxation time (1/2RT), maximal twitch tension (Pt), and maximal tetanic tension (Po). The experimental leg was subjected to a 2 hour tourniquet which was placed around the thigh. Muscles of this leg were tested following a 2 hour recovery period. In three of the five animals, no response could be elicited from either the plantaris or soleus muscles of the experimental leg. In those instances where the experimental muscles were capable of generating force, the plantaris was clearly more effected. While tension production in the soleus was reduced by approximately 55%, the plantaris exhibited approximately a 90% decrease in tension output. Furthermore, both TPT and 1/2RT demonstrated consistent changes. These results indicate that the contractile properties of both the soleus and plantaris are dramatically effected by a 2 hour tourniquet. They further suggest that there may be a differential response based upon fiber type.

Animals↗
PubMedDate not supplied

Skeletal muscle profiles among elite long, middle, and short distance swimmers.

Skeletal muscle profiles of fiber composition and leg power and strength were obtained in 30 national caliber swimmers (20 males, 10 females). Subjects were classified into three groups based upon the distance of their primary events [long distance (LDS), middle distance (MDS), and short distance (SDS) swimmers]. Intergroup analyses showed that the LDS group had the highest values of percent Type I muscle fiber composition (percent Type I and percent Type I area), and the lowest values of leg power and strength values (vertical jump and torque-velocity relationships). In addition, when grouped by Type I fiber composition, subjects having greater than or equal to 50% Type I fibers had significantly lower vertical jump and torque values than those having less than 50% Type I fibers. Overall, the compositional and functional measurements were consistent with the specific metabolic and contractile demands of the different swim groups.

Adolescent↗
PubMedDate not supplied

Skeletal muscle profiles in elite springboard and platform divers.

This investigation determined the vastus lateralis muscle fiber composition, as well as leg power and strength, in a group of 10 world class divers. Male divers had a low mean percentage of Type I fibers (36%), which was consistent with the functional demands of their sport, whereas females had a mean value of 61%. The ratio of Type I/Type II cross-sectional fiber area was 0.95 in females and 0.82 in males. Angle-specific torque-velocity relationships, derived from Cybex testing of the knee extensors, revealed high torque values in males but not in females. The observed male-female differences have no clear explanation, unless muscle fiber composition has greater importance in the more difficult dives executed by men.

Adolescent↗
PubMedDate not supplied

The in vivo force-velocity relationship of the knee flexors and extensors.

Previous studies have compared the torque production of the knee flexors and extensors and developed a "hamstring-quadricep" ratio. Collectively, these studies indicate that the ratio of strength between the knee flexors and extensors is a function of test speed, with the ratio increasing at the faster test speeds. Unfortunately, these studies have employed the peak torque isokinetic method for making measurements. This technique suffers from a number of problems that are biomechanical and physiological in nature. Consequently, in this study, we employed comparison of the in vivo force-velocity relationship using an angle-specific method and a gravitational correction factor to more accurately determine flexor-extensor ratios and to better describe any variations occurring as a function of test speed. Nine male subjects volunteered to participate in this study. Each of the subjects participated in two test sessions. Subjects were tested at six angular velocities of 0, 48, 96, 144, 192, 240 deg/sec. At these respective test speeds, the mean flexor torques were 95.0, 94.8, 84.1, 66.2, 56.2, and 49.2 Nm, respectively. The corresponding values for the knee extensors were 252.2, 246.5, 220.7, 184.5, 161.9, and 146.4 Nm. Normalization of these torque-velocity relationships demonstrated that the in vivo force-velocity relationships of the two muscle groups are similar at slow speeds, but become disparate at higher velocities. When examining flexor-extensor torque ratios at the various test speeds, it was found that there were significant differences (P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

Isokinetic torque imbalances in the rotator cuff of the elite water polo player.

The specific repetitive activity of water polo, like baseball pitching, emphasizes adduction and internal rotation. This study used the Cybex II to evaluate the isokinetic strength of the rotator cuff in elite water polo players and in a group of control subjects. The water polo players were significantly stronger than the controls. Of greater importance was the confirmation of imbalances in the rotator cuff force couples of adduction/abduction and external/internal rotation. These changes are similar to those reported for pitchers. The adductors in the water polo group had gained in relative strength resulting in an increase in the adduction/abduction ratio to about 2:1. The internal rotators had gained in relative strength resulting in a decrease in the external/internal ratio to about 0.6:1. For both force couples the differences are more apparent at a slow speed. Side-to-side differences were not significant.

Biomechanical Phenomena↗
PubMedDate not supplied

Shoulder torque changes in the swimming athlete.

Torque production was assessed in the shoulders of competitive men and women swimmers for the motions of abduction, adduction, and external and internal rotation. Testing was performed on the Cybex II dynamometer and the results were compared to controls. In addition, the ratios of torque development for adduction:abduction and external rotation:internal rotation were evaluated. The results demonstrated a statistically significant increase in torque production in swimmers for most motions tested. Statistically significant ratio shifts were also noted. The ratio of adduction:abduction increased and that for external rotation:internal rotation decreased. We think these shifts in the torque ratios in swimmers' shoulders resulted from sport-specific repetitive activity that emphasizes adduction and internal rotation.

Adolescent↗