Omri Inbar

Normal cardiopulmonary responses during incremental exercise in 20- to 70-yr-old men.

Healthy men (N = 1424, age 20-70 yr) underwent a progressive incremental treadmill exercise test to volitional maximum. Cardiopulmonary variables were measured breath-by-breath. The aerobic power (VO2max) declined at an average yearly rate of 0.33 ml.kg.-1min-1, HRmax declined 0.685 beats.min-1.yr-1, and max O2 pulse declined at an annual rate of 0.115 ml.beat-1.kg-1*100. Gas exchange threshold (GET) expressed as percentage of VO2max was 58% and 69% in the youngest (20-30 yr) and oldest (61-70 yr) decades, respectively. The average decline in VE, Vt, f, and PETCO2 over the entire age range was 29%, 10%, 21%, and 7%, respectively. There were increases in VE/VO2, and VE/VECO2, from age 20-70 yr of 13% and 14%, respectively, but no changes across 5 decades in PETO2. Physical (height and weight) as well as life-style characteristics (leisure time activity, place of residency, smoking), were found to be potent predictors in most of the cardiopulmonary values at maximal exercise and therefore should be incorporated in the predictive equations for such variables. Normal response patterns of most cardiopulmonary variables throughout the range of exercise intensities were shown to be age-affected and thus should be standardized for age decades.

Comparison of thermoregulatory responses to exercise in dry heat among prepubertal boys young adults and older males

The purpose of this investigation was to compare the thermoregulatory responses during exercise in a hot climate among three age categories. Eight prepubertal (PP), eight young adult (Y) and eight elderly (O) male subjects cycled at an intensity of 50 ± 1% of their maximum oxygen uptake for 85 min (three 20 min bouts with three 7 min rest periods) in hot and dry conditions (41 ± 0.67°C, 21 ± 1% relative humidity). During the exercise‐in‐heat protocol, rectal temperature (Tre) skin temperatures (Tsk), heart rate (HR), , RER, sweat rate, and the number of heat activated sweat glands (HASG) were determined. Despite highest and lowest end‐exposure Tre in the Y and O groups, respectively, the rise in rectal temperature (accounting for differences in baseline Tre) was similar in all age groups. Changes in body heat storage (ΔS), both absolute and relative to body mass, were highest in the Y and O groups and lowest in the PP group. While end‐session as well as changes in mean skin temperature were similar in all three age groups, HR (absolute and percentage of maximum) was significantly lower for the O compared with the PP and Y groups. Total body as well as per body surface sweating rate was significantly lower for the PP group, while body mass‐related net metabolic heat production ((M−W) kg−1) and heat gained from the environment were highest in the PP and lowest in the O group. Since mass‐related evaporative cooling (Esk kg−1) and sweating efficiency (Esk/Msw kg−1) were highest in the PP and lowest in the O group, the mass‐dependent heat stored in the body (ΔS kg−1) was lowest in the PP (1.87 ± 0.03 W kg−1) and highest in Y and O groups (2.19 ± 0.08 and 1.97 ± 0.11 W kg−1, respectively). Furthermore, it was calculated that while the O group required only 4.1 ± 0.5 W of heat energy to raise their body core temperature by 1°C, and the Y group needed 6.9 ± 0.9 W (1°C)−1, the PP group required as much as 12.3 ± 0.7 W to heat up their body core temperature by 1°C. These results suggest that in conditions similar to those imposed during this study, age and age‐related characteristics affect the overall rate of heat gain as well as the mechanisms through which this heat is being dissipated. While prepubertal boys seem to be the most efficient thermoregulators, the elderly subjects appear to be the least efficient thermoregulators.

Specific inspiratory muscle training in well-trained endurance athletes

PURPOSE It has been reported that arterial O2 desaturation occurs during maximal aerobic exercise in elite endurance athletes and that it might be associated with respiratory muscle fatigue and relative hypoventilation. We hypothesized that specific inspiratory muscle training (SIMT) will result in improvement in respiratory muscle function and thereupon in aerobic capacity in well-trained endurance athletes. METHODS Twenty well-trained endurance athletes volunteered to the study and were randomized into two groups: 10 athletes comprised the training group and received SIMT, and 10 athletes were assigned to a control group and received sham training. Inspiratory training was performed using a threshold inspiratory muscle trainer, for 0.5 h x d(-1) six times a week for 10 wk. Subjects in the control group received sham training with the same device, but with no resistance. RESULTS Inspiratory muscle strength (PImax) increased significantly from 142.2 +/- 24.8 to 177.2 +/- 32.9 cm H2O (P < 0.005) in the training but remained unchanged in the control group. Inspiratory muscle endurance (PmPeak) also increased significantly, from 121.6 +/- 13.7 to 154.4 +/- 22.1 cm H2O (P < 0.005), in the training group, but not in the control group. The improvement in the inspiratory muscle performance in the training group was not associated with improvement in peak VEmax, VO2max breathing reserve (BR). or arterial O2 saturation (%SaO2), measured during or at the peak of the exercise test. CONCLUSIONS It may be concluded that 10 wk of SIMT can increase the inspiratory muscle performance in well-trained athletes. However, this increase was not associated with improvement in aerobic capacity, as determined by VO2max, or in arterial O2 desaturation during maximal graded exercise challenge. The significance of such results is uncertain and further studies are needed to elucidate the role of respiratory muscle training in the improvement of aerobic-type exercise capacity.

Swimming and asthma. Benefits and deleterious effects.

SummarySwimming is a common pastime activity and competitive sport for patients with asthma. One reason for such popularity may be the low asthmogenicity of swimming compared with land-based activities. Review of available evidence suggests that swimming induces less severe bronchoconstriction than other sports. The mechanisms for this protective effect of swimming are not clear, but there is some experimental evidence intimating that it results in part from the high humidity of inspired air at water level, which reduces respiratory heat loss (and possibly osmolality of airways mucus). Beneficial roles of horizontal posture and of water immersion have been tested but not confirmed. Swimming poses two potentially deleterious effects to the patient with asthma. One is the exaggerated parasympathetic tone due to the ‘diving reflex’, that has been shown to trigger bronchoconstriction. The other is airway irritation because of chlorine and its derivatives. Swimming as a training modality has definite benefits for the patient with asthma. These include an increase in aerobic fitness and a decrease in asthma morbidity. There is no conclusive evidence, however, that swim training causes a decrease in the severity or frequency of exercise-induced bronchoconstriction.

Changes in muscle metabolites in females with 30-s exhaustive exercise.

The purpose of this study was to quantify the changes in selected intramuscular metabolites associated with non-oxidative energy metabolism after performance of the Wingate Test (WT), a widely used, exhaustive, 30-s cycle test of short-time muscular power. Muscle biopsies were taken from the m. vastus lateralis of nine female physical education students at rest and immediately after performance of the WT. The concentrations of adenosine triphosphate (ATP), creatine phosphate (CP), lactate, and glycogen were determined. The ATP decreased from 20.9 to 13.8; CP decreased from 62.7 to 25.1; lactate increased from 9.0 to 60.5; and glycogen decreased from 360 to 278 (all concentrations are mmol X kg-1 dry muscle). The absolute changes in CP and lactate were not as large as those reported in other exercise studies. Based on the metabolite changes, it was concluded that the WT is a satisfactory test of the maximal muscular power that can be generated from non-oxidative metabolism, but that the 30-s duration of the test probably does not tax the maximal capacity of such energy metabolism.

Physiological responses to incremental exercise in patients with chronic fatigue syndrome.

PURPOSE The purpose of this investigation was to characterize the physiological response profiles of patients with chronic fatigue syndrome (CFS), to an incremental exercise test, performed to the limit of tolerance. METHODS Fifteen patients (12 women and three men) who fulfilled the case definition for chronic fatigue syndrome, and 15 healthy, sedentary, age- and sex-matched controls, performed an incremental progressive all-out treadmill test (cardiopulmonary exercise test). RESULTS As a group, the CFS patients demonstrated significantly lower cardiovascular as well as ventilatory values at peak exercise, compared with the control group. At similar relative submaximal exercise levels (% peak VO(2)), the CFS patients portrayed response patterns (trending phenomenon) characterized, in most parameters, by similar intercepts, but either lower (VCO(2), HR, O(2pulse), V(E), V(T), PETCO(2)) or higher (B(f), V(E)/VCO(2)) trending kinetics in the CFS compared with the control group. It was found that the primary exercise-related physiological difference between the CFS and the control group was their significantly lower heart rate at any equal relative and at maximal work level. Assuming maximal effort by all (indicated by RER, PETCO(2), and subjective exhaustion), these results could indicate either cardiac or peripheral insufficiency embedded in the pathology of CFS patients. CONCLUSION We conclude that indexes from cardiopulmonary exercise testing may be used as objective discriminatory indicators for evaluation of patients complaining of chronic fatigue syndrome.

The effects of alkaline treatment on short‐term maximal exercise

Abstract The effects of alkalosis on submaximal and maximal exercise performance of a relatively long duration have been investigated previously. The present study examined the effects of sodium bicarbonate ingestion on cycling performance of the 30 s Wingate Anaerobic Test using 13 male physical education students. Three hours prior to exercise, subjects ingested either table salt (control) or sodium bicarbonate (alkalosis) of equimolar dosage (10 and 13 g, respectively) in capsule form. Biopsies were taken from the m. vastus lateralis for determination of muscle fibre composition. Resting blood pH was 7.43±0.01 (mean±s.e.) for the alkaline condition versus 7.37 + 0.01 for the control condition (P < 0.01). Mean power output increased significantly (P<0.05) following alkaline treatment. Peak power output was not affected. No relationship was found between fibre type distribution and sensitivity to the alkaline treatment. The increased alkali reserve reduced mean post‐exercise acidosis by 0.05 pH units (P<...

Differences between swimming and running as stimuli for exercise-induced asthma

SummaryThirteen children each exercised for 6 min by running on a treadmill and by tethered swimming, breathing air at room temperature and either 8% or 99% relative humidity continuously. Ventilation, gas exchange and heart rate were closely matched in all four tests in each child, with a mean oxygen consumption of 32.3±1.7ml·min−1·kg−1. The post-exercise fall in FEV1 expressed as a percentage of the baseline FEV1 (δFEV1) was significantly greater after running compared with swimming breathing either humid or dry air. The δFEV1 was also related to respiratory heat loss (RHL) calculated from measurements of inspired and expired gas temperature and humidity. At a standardised RHL, the difference between running and swimming was highly significant [δFEV1 (%) ± SE=39±5 and 28±4 respectively, p<0.01]. These experiments suggest that the type of exercise influences the severity of exercise-induced asthma even under conditions of the same metabolic stress and respiratory heat loss.

Physiological effects of a sports rehabilitation program on cerebral palsied and post-poliomyelitic adolescents.

Thirty-four spastic cerebral palsied (CP) post-poliomyelitic (P) adolescents (mean age--17.9 years) participated in a twice-a-week mild conditioning program, lasting 12 months. Nine CP adolescents served as a control inactive group. The post-conditioning submaximal heart rates of the CP active group were significantly lower during 75 and 150 kpm/min work loads on an arm ergometer, compared with the respective values at the beginning of the program. Peak O2 uptake values, directly measured during an all-out arm pedalling test, were improved by some 8% in the CP active group. Neither CP inactive nor P active showed any significant changes attributable to conditioning in physiological variables obtained during the submaximal or maximal tests. Adiposity level of each of the three groups remained unchanged. The mechanical efficiency of all subjects was low (16.2%) and remained so following conditioning.

The effect of bicycle crank-length variation upon power performance

The purpose of the present study was to define the optimal bicycle crank length (CL) for eliciting maximal leg power output during a 30 s power test (Wingate Anaerobic Test). Thirteen male students 22-27 years old served as subjects for this study. In each of the five sessions the test was administered on a mechanically braked cycle-ergometer modified by a crank slider-assembly which permitted continuous crank-length adjustment. Five evenly spaced CLs, centred around the conventional 17.5 cm crank, ranging from 12.5 to 22.5 cm, were used. The measured variables were mean (MP) and peak (PP) power output. A parabola-fitting technique was employed to define the optimal CL from the MP and PP data. The resulting optimal CL was 16.4 and 16.6 cm for MP and PP, respectively. Optimal CL was shown to depend on leg length. However, within a two crank length span (± 5 cm) about the optimal crank length MP and PP did not vary by more than 0.77 and 1.24% respectively. It is suggested that for a homogenous population, s...