Role of physical activity training in attenuation of height loss through aging.

BACKGROUND: Although the genetic contribution to variability in bone mass has been estimated to be as high as 80%, evidence continues to accumulate suggesting that factors such as physical activity can influence bone mass which may avoid compression of the vertebrae leading to slower stature decline with age. OBJECTIVES: This study examines whether regular exercise has the potential of positively affecting the aging process with regard to height loss. METHODS: The height of 957 females and 1,088 males who were 35-55 years of age in 1965 were measured again in 1995. Based on a questionnaire, the subjects were divided into four groups. Group A (80 females, aged 73. 2 +/- 6 years, and 141 males, aged 72.1 +/- 5.7 years) represented subjects who were engaged in moderate vigorous aerobic activity throughout their lives; group B (95 females, aged 73.6 +/- 5.5 years, and 207 males, aged 71.7 +/- 6.1 years) were subjects who started their moderate vigorous aerobic activity around the age of 40 and kept their activity until the present time; group C (362 females, aged 73.2 +/- 5 years, and 390 males, aged 71.1 +/- 6 years) were persons who were active as young adults, but did not continue to exercise, and group D (425 females, aged 72.8 +/- 5.3 years, and 350 males, aged 70.9 +/- 6.1 years) were subjects who had not exercised regularly throughout their lives. RESULTS: All subjects lost height due to aging. However, significant (p < 0.05) differences in rate of height loss were found among the A, B, C, and D groups: for females 3.4 +/- 0.7, 3.5 +/- 0.8, 6.0 +/- 0.5, and 6.5 +/- 0.7 cm, respectively; for males 2.6 +/- 0.5, 3.1 +/- 0.4, 5.3 +/- 0.4, and 5. 5 +/- 0.5 cm, respectively. In addition, the females' height loss rate was significantly (p < 0.05) higher than that of the males in all four activity categories. CONCLUSIONS: These data suggest that lifelong moderate endurance training, especially after the age of 40 years, is associated with attenuation of height loss in both sexes. However, the magnitude of the attenuation is significantly higher in males.

[Odor perception in relation to age, general health, nutritional status, and dental status]. / Geurperceptie in relatie tot leeftijd, algemene gezondheid, voedingstoestand en gebitsstatus.

Many studies have shown that odour perception declines with age. Considering the possible role of age-related phenomena such as general health, dental health and nutrition in such a decline, their joint effect on variability in odour perception was evaluated in the present study. 73 apparently healthy adults aged from 53 to 86 years (median age = 66), living in the community, took part in this study. The SENIEUR protocol was used to assess the general health status and anthropometric measures were obtained to assess the nutritional status. The sensory detection threshold for isoamylacetate (banana odour) was determined as the lowest detectable odour concentration. Dental status was assessed by a questionnaire on the presence of natural teeth and wearing of dentures. Those in poor general health had significantly higher mean odour thresholds (2.35, SD = 1.34), where threshold concentration was expressed as -log(mol/l), than those in good (3.47, SD = 1.46) or reasonably general health (3.75, SD = 1.02). Partial denture wearers had significantly higher odour thresholds (2.99, SD = 1.12) than those having only natural teeth (4.24, SD = 1.43). Significant correlations between age and anthropometrical values were found, indicating that with age, muscle mass particularly in women decreases (r = -0.50). Odour perception of women correlated significantly inversely with triceps skinfold thickness (r = -0.42), indicating that poor sense of small is associated with high body content of fat. Our results indicate that general health and dental state are important age-associated factors in odour perception. Since age does not show a significant independent effect, neither in an analysis of variance, nor in a multiple regression analysis, such factors tend to become more important than chronological age per se.

Odour perception in relation to age, general health, anthropometry and dental state.

Considering the possible role of age-related phenomena such as general health, dental health and nutrition in odour perception, their joint effect on variability in odour perception was evaluated in the present study. A total of 171 apparently healthy adults with a mean age of 66.0 years (S.D. 7.3), ranging between 53 and 86 years, living in the community took part in this study. The SENIEUR protocol was used to assess the general health status and anthropometric measures were obtained to assess the nutritional status of the persons. The sensory detection threshold for isoamyl acetate was determined to measure odour perception. Oral examinations were used to assess dental status. Those in poor general health had lower mean values for odour perception than those in good or reasonably general health. Complete denture wearers and those with partial dentures had significantly lower values for odour perception than those with only natural teeth. Odour perception correlated significantly with measures of body fat and muscle mass, indicating that a poor sense of smell is associated with low body fat and muscle area. Our results indicate that general health and dental state are important age-associated factors in odour perception. Since odour perception is an important determinant of food consumption, early detection of diminished odour perception might be an indication of physical deterioration.

Cardiac output variations in supine resting subjects during head-out cold water immersion.

Five men, aged 31.2 years (SD 2.3), under semi-nude conditions and resting in a dorsal reclining position, were exposed to thermoneutral air for 30 min, followed immediately by a cold water (15 degrees C) immersion for 60 min. Cardiac output was measured using a dual-beam Doppler flow meter. During immersion in cold water, cardiac frequency (fc) showed an initial bradycardia. The lowest values were reached at about 10 min after immersion, 58.3 (SD 2.5) to 48.3 (SD 7.8) beats min-1 (P < 0.05). By the 20th min of exposure, fc had gradually risen to 70.0 beats min-1 (SD 6.6, P < 0.05). This change could be due to the inhibition of the initial vagal reflex by increased catecholamine concentration. Stroke volume (Vs) was significantly increased (P < 0.05) during the whole cold immersion period. Cardiac output, increased from 3.57 (SD 0.50) to 6.26 (SD 1.33) l min-1 (P < 0.05) and its change with time was a function of both Vs and fc. On the other hand, systolic flow acceleration was unchanged during the period of immersion. The changes in the respiratory variables (ventilation, oxygen uptake, carbon dioxide output and respiratory exchange ratio) during immersion showed an initial hyperventilation followed, as immersion proceeded, by a slower metabolic increase due to shivering.

Factors enhancing cardiac output in resting subjects during cold exposure in air environment.

Six young males, in semi-nude conditions, resting in dorsal reclining position, were exposed successively to a thermoneutral environment (30 min), a cold environment (1 degree C) (Cold) or thermoneutrality (Control) (120 min), and during 60 min recovery in thermoneutral conditions. Cardiac output has been measured using a Dual Beam Doppler. During cold stress a significant increase of heart rate (66.4 +/- 6.4 to 91.0 +/- 14.9 beats.min-1), systolic blood pressure (119.5 +/- 7.8 to 218.7 +/- 18.7 mmHg), diastolic blood pressure (68.1 +/- 11.7 to 114.3 +/- 28.3 mmHg) and cardiac output (5.42 +/- 0.96 to 8.08 +/- 1.28 l.min-1) were observed. On the contrary initial systolic aorta flow acceleration is significantly lowered (1130 +/- 120 to 840 +/- 170 cm.s-2). Systolic ejection volume remained unchanged throughout the whole experiment. Increase in cardiac output during cold air (1 degree C) exposure is thus only imputed to the higher heart rate partly due to hypersecretion of catecholamines. The diminution of the blood flow acceleration could be related to a lesser arterial compliance and/or to the cold induced hemoconcentration. Enhanced heart's mechanical work due to sympathetic stimulation, seems thus to be absorbed by the increase in the peripheral resistance.

Reversal of cold induced haemoconcentration.

Classically, cold induced plasma volume reduction is explained by an increased diuresis which is generated by an inhibition of antidiuretic hormone release. However, most of the haemoconcentration appears to be reversible during rewarming. This observation weakens the former statement. The aim of this study was to clarify the mechanisms involved in the reversal of the cold induced haemoconcentration. Six young males, resting in a dorsal reclining position, were exposed successively to a thermoneutral environment (30 min), a cold environment (1 degrees C; cold) or thermoneutrality (control) for 120 min, and during a 60-min recovery period in thermoneutral conditions. During cold stress, a reduction of 15% (i.e. 510 ml) of the plasma volume was observed, and osmolality was unchanged. After the 60-min recovery under thermoneutral conditions, plasma volume variation between the Cold and the Control experiments was reduced and reached 3% (i.e. 100 ml). This volume equalled the increased amount of urine production observed during the cold stress experiment. Haemoconcentration cannot be explained by increased urinary water loss (+/- 100 ml) alone. Therefore a transient shift of plasma water from vascular to interstitial spaces, due to an increase of blood pressure, could be involved in the reduction of plasma volume.

Physiological adjustments of facial cooling during exercise.

Physiological and metabolic output responses to facial cooling during a graded maximal exercise and a prolonged submaximal exercise lasting 30 min at 65% VO2 max were investigated in five male subjects. Pedalling on a cycle ergometer was performed both with and without facial cooling (10 degrees C, 4.6 M.S-1). Facial cooling at the end of greated maximal exercise apparently had no effect on plasma lactate (LA), maximal oxygen consumption (VO2 max), maximal heart rate (HR max), rectal temperature (Tre), work load, lactate threshold (LT), ventilatory threshold (VT) and onset of blood lactate accumulation (OBLA). However, the response to facial cooling after prolonged submaximal exercise is significantly different for heart rate and work load. The results suggest that facial wind stimulation during maximal exercise does not produce a stress high enough to alter the metabolic and physiological responses.

Spectral resolution of cardio-circulatory variations in men measured by autorhythmometry over 2 years.

An analogue of the periodogram method for unequally spaced data is presented with a view to resolving the frequency structure of the observations. The algorithm is explicitly based on the sequential least squares procedure. In particular, the key concept is that the within-plot spectral analysis can be augmented by the between-plot information to make inferences about common characteristics. It is also shown how the between-plot random variations can be incorporated into the multiple harmonic regression model. A detailed spectral analysis investigates the periodic fluctuations in four cardio-circulatory variables, measured by autorhythmometric observation by eight men at rest and extending over a time span of 2 years. The spectral curves show the existence of circadian and circaseptan rhythmicities. The amplitude modulation of the dian rhythm by circaseptan variation is assimilated with the rhythmicity of work during the week. The blood-pressure variables situate their maximum annual peak in the winter period. These quasi-periodic fluctuations appear to be related to the amount of physical activity performed in time by the subjects.

Rheological modelling of physiological variables during temperature variations at rest.

The evolution with time of cardio-respiratory variables, blood pressure and body temperature has been studied on six males, resting in semi-nude conditions during short (30 min) cold stress exposure (0 degree C) and during passive recovery (60 min) at 20 degrees C. Passive cold exposure does not induce a change in HR but increases VO2, VCO2, Ve and core temperature Tre, whereas peripheral temperature is significantly lowered. The kinetic evolution of the studied variables was investigated using a Kelvin-Voigt rheological model. The results suggest that the human body, and by extension the measured physiological variables of its functioning, does not react as a perfect viscoelastic system. Cold exposure induces a more rapid adaptation for heart rate, blood pressure and skin temperatures than that observed during the rewarming period (20 degrees C), whereas respiratory adjustments show an opposite evolution. During the cooling period of the experiment the adaptative mechanisms, taking effect to preserve core homeothermy and to obtain a higher oxygen supply, increase the energy loss of the body.

Hematological variations at rest and during maximal and submaximal exercise in a cold (0 degree C) environment.

The affect of negative thermal stress on hematological variables at rest, and during submaximal (sub ex) and maximal exercise (max ex) were observed for young males who volunteered in two experimental sessions, performed in cold (0 degree C) and in normal room temperature (20 degrees C). At rest, hematological variables such as RBC and derivates Hb and Hct were significantly increased (P less than 0.05) during cold stress exposure, while plasma volume decreased. The findings of this study suggest that the major factor inducing hypovolemia during low thermal stress can be imputed to local plasma water-shift mechanisms and especially to a transient shift of plasma water from intra- to extravascular compartments. Rest values for WBC and platelets (Pla) were also slightly increased during cold stress exposure. However this increase can partly be related to hemoconcentration but also to the cold induced hyperventilation activating the lung circulation. Maximal exhaustive exercise induced, in both experimental temperatures, significant (P less than 0.05) increments of RBC, Hb, Hct, and WBC while plasma volume decreased. However, Pla increase was less marked. On the other hand, cold stress raised slightly the observed variations of the different hematological variables. Submaximal exercise induced a similar, though non-significant, pattern for the different hematological variables in both experimental conditions. Observed plasma volume (delta PV%) reduction appears during exercise. However cold stress induced resting plasma volume variations that are transferred at every exercise level. Neither exercise nor cold inducement significantly modified the hematological indices (MCH, MCV, MCHC). In conclusion hematological variables are affected by cold stress exposure, even when subjects perform a physical activity.

Metabolic and hormonal responses during exercise at 20 degrees, 0 degrees and -20 degrees C.

This study was designed to clarify the effects of cold air exposure on metabolic and hormonal responses during progressive incremental exercise. Eight healthy males volunteered for the study. Informed consent was obtained from every participant. The following protocol was administered to each subject on three occasions in a climatic chamber in which the temperature was 20 degrees, 0 degree or -20 degrees C with relative humidity at 60% +/- 1%. Exercise tests were conducted on an electrically braked ergocycle, and consisted of a progressive incremental maximal exercise. Respiratory parameters were continuously monitored by an automated open-circuit sampling system. Exercise blood lactate (LA), free fatty acids (FFA), glucose levels, bicarbonate concentration (HCO-3), acid-base balance, plasma epinephrine (E) and norepinephrine (NE) were determined from venous blood samples obtained through an indwelling brachial catheter. Maximal oxygen uptake was significantly different between conditions: 72.0 +/- 5.4 ml kg-1 min-1 at 20 degrees C; 68.9 +/- 5.1 ml kg-1 min-1 at 0 degree C and 68.5 +/- 4.6 ml kg-1 min-1 at -20 degrees C. Workload, time to exhaustion, glucose levels and rectal temperature decreased significantly at -20 degrees C. Catecholamines and lactate values were not significantly altered by thermal conditions after maximal exercise but the catecholamines were decreased during rest. Bicarbonate, respiratory quotient, lactate and ventilatory thresholds increased significantly at -20 degrees C. The data support the contention that metabolic and hormonal responses following progressive incremental exercise are altered by cold exposure and they indicate a marked decrease in maximal oxygen uptake, time to exhaustion and workload.

Effects of selective cooling of the facial area on physiological and metabolic output during graded maximal or prolonged submaximal exercise.

Physiological and metabolic output responses to facial cooling during a graded maximal exercise and a prolonged submaximal exercise lasting 30 min at 65% VO2 max were investigated in five male subjects. Pedalling on a cycle ergometer was performed both with and without facial cooling (10 degrees C, 4.6 m s-1). Facial cooling at the end of graded maximal exercise apparently had no effect on plasma lactate (LA), maximal oxygen consumption (VO2 max), maximal heart rate (HR max), rectal temperature (Tre), work-load, lactate threshold (LT), ventilatory threshold (VT) and onset of blood lactate accumulation (OBLA). However, the response to facial cooling after prolonged submaximal exercise is significantly different for heart rate and work-load. The results suggest that facial wind stimulation during maximal exercise does not produce a stress high enough to alter the metabolic and physiological responses.

[Hematological variations with submaximal long-term physical exercise]. / Variations hematologiques à l'exercice physique sous maximal de longue durée.

The purpose of this study was to determine the effects of cold stress on routine hematologic parameters when subjects are submitted on long-lasting exercise. Eight male subjects, aged 22.7 +/- 1.3 years with a peak oxygen consumption of 54.3 +/- 5.2 mL/kg/min performed, respectively at 20 degrees C and 0 degrees C, a two-hour submaximal cyclergometry at an intensity of 40% of that performed during a previous exhaustive test. A 21-gauge catheter was inserted into an ante cubital vein for collection of the blood samples. Platelets and WBC count was significantly (p less than 0.05) increased during exercise in both 20 degrees C and 0 degrees C environmental temperatures. A slight but not statistically significant increase of RBC, Hb and Hct and a plasma concentration during cold exposure was observed. Indices are unchanged in both experiments. The findings of this study suggest that physical exercise is a major factor inducing hypervolemia and that low thermal environment does not appear to be an effective factor influencing hematologic variables during exercise.

Lactate threshold and onset of blood lactate accumulation during incremental exercise after dietary modifications.

This study was designed to clarify the effects of dietary modifications on the lactate threshold (LT) and on the onset of blood lactate accumulation (OBLA) during progressive incremental exercise. Six healthy males volunteered for the study. Informed consent was obtained from every participant. The following protocol was administered to each subject on three occasions: a 48-h period of mixed dieting (53% carbohydrates, 30% lipids, 17% proteins) preceding the first exercise test, immediately followed by a 48-h period of either a carbohydrate-rich (68% CHO, 23% lipids, 9% proteins) or a fat-rich (19% CHO, 57% lipids, 26% proteins) iso-caloric diet leading to the second exercise and separated from the third test by a 12-days period. Exercise tests were conducted on an electrically-braked ergocycle, and consisted of a progressive incremental maximal exercise. Respiratory parameters were continuously monitored by an automated open circuit sampling system. Exercise blood lactate (LA), free fatty acids (FFA), glucose levels and acid-base balance were determined from venous blood samples obtained through an indwelling brachial catheter. Peak lactate values, workload and performance time were not significantly altered by imposed diets. Furthermore, dietary modifications had no significant effect on LT, OBLA fixed at 4 mmol and ventilatory threshold. Increased pH and FFA mobilization were observed with fat-rich diet, while CHO-rich diet markedly increased the respiratory exchange ratio (R). It is concluded that LT and OBLA are not significantly altered by fat or CHO enrichment of diets.

[Endurance bicycle ergometry at 0 degrees C: cardio-respiratory and metabolic course]. / Cyclergométrie épuisante à 0 degr'es C: evolution cardio-respiratoire et métabolique.

The purpose of the present study is to determine the physiological and metabolic variations during and after an exhaustive exercise in different thermal conditions (0 degree C and 20 degrees C). For the eleven experimental subjects, the maximal power output is the same at 0 degrees C and 20 degrees C: 330 +/- 30 W (Mean +/- s). The heart rate is lower (bradycardia) at rest, exhaustion, and recovery. However, these differences are only significant (p less than 0.05) at exhaustion. The oxygen consumption and pulmonary ventilation is higher at 0 degree C in comparison with the measurements at 20 degrees C. The blood lactate concentrations are significantly lower at 0 degree C and we observe the inverse phenomenon for the bicarbonates. The bases excess was significant at 4, 6 and 10th minute of recovery time. These values are higher for the measurements taken at 0 degree C. The results have shown that the cold stress after an exhaustive exercise and during recovery, can induce a physiological and metabolic response unlike of those at 20 degrees C.