Concurrent resistance and aerobic training as protection against heart disease.

This study was designed to compare the effects of aerobic and concurrent aerobic and resistance training on their ability to slow the rate of development and progression of coronary heart disease (CHD) in young adult males at low risk, as determined by the Framingham risk assessment (FRA) score. Subjects were assigned to 16 weeks of three-times weekly aerobic training (AT) (n = 13), concurrent aerobic and resistance training (CART) (n = 13) or no exercise (NO) (n = 12). Both AT and CART resulted in significant (p < 0.05) changes in total cholesterol (from 173.67 ± 29.93 to 161.75 ± 26.78 mg.dl(-1) and from 190.00 ± 38.20 to 164.31 ± 28.73 mg.dl(-1), respectively), smoking status (from 12.25 ± 5.08 to 10.33 ± 5.37 cigarettes per day and 12.00 ± 4.71 to 8.77 ± 5.10 cigarettes per day, respectively), high-density lipoprotein cholesterol (from 47.00 ± 11.85 to 57.50 ± 5.99 mg.dl(-1) and 34.00 ± 8.53 to 46.77 ± 14.32 mg.dl(-1), respectively), systolic blood pressure (from 126.17 ± 7.00 to 122.33 ± 3.17 mmHg and 131.54 ± 9.28 to 121.69 ± 7.87 mmHg, respectively) and therefore FRA score (from 3.58 ± 2.19 to 1.33 ± 2.27 and 5.77 ± 3.09 to 2.46 ± 2.90, respectively). Both modes of exercise were found to be equally effective in reducing CHD risk. These findings support the inclusion of resistance training into an aerobic training programme to lower CHD risk, which will afford subjects the unique benefits of each mode of exercise.

Congenital eunuchism and Favorinus.

Ancient Hebrew literature as well as the New Testament differentiate between castrated eunuchs and congenital eunuchs. Congenital eunuchism is very rare today, and assuming that this was also the case in classical times, we investigated possible reasons why congenital eunuchs feature prominently. We discuss the probability that the concept 'congenital eunuchism' might in ancient times have included effeminate men who, according to cultural views on 'maleness' and androgyny, were almost equated with eunuchs. The causes of congenital hypogonadism are reviewed in order to attempt clarification of the condition of Favorinus, a congenital eunuch in the second century AD. We suggest that although he might have been a true hermaphrodite, as suggested by some authors, it is more likely that he had one of the following conditions: functional prepubertal castrate syndrome, testicular gonadotrophin insensitivity, selective gonadotrophin deficiency or Reifenstein's syndrome.

Effect of a high carbohydrate diet on core temperature during prolonged exercise.

This study compared the effects of a high-carbohydrate and a mixed diet on core temperature responses to prolonged exercise in six male competitive cyclists (age = 22.2 +/- 1.9 years). This study, the first to investigate the effect of a high-carbohydrate diet on exercise core temperature in humans, therefore suggests that three days of increased dietary carbohydrate intakes do not evoke any deleterious thermoregulatory responses during prolonged submaximal exercise.

Intravascular Hemolysis in Aerobic Dancing: The Role of Floor Surface and Type of Routine.

In brief: The effect of aerobic dancing on intravascular hemolysis was studied in 65 healthy women (aged 18 to 50 years) who were assigned to one of four groups according to the type of routine performed and the hardness of the floor surface. All subjects participated in a 60-minute dance session; a subgroup participated in five successive 60-minute sessions with one hour of rest between sessions. Blood was tested for both groups before and after exercise; urine was tested similarly for the subgroup only. The findings indicated that intravascular hemolysis occurred and that it was influenced by the type of routine, hardness of the surface, and duration of dancing. However, the degree of hemolysis was small and unlikely to contribute to the development of anemia.

The South African Defence Force physical training programme. Part I. Effect of 1 year's military training on endurance fitness.

The effect of the South African Defence Force's (SADF) military training on the endurance fitness of recruits was investigated. Pre-military training maximal O2 consumption (53,14 ml/kg/min) did not change significantly during the study. In contrast, lactate turnpoint (ml O2/kg/min) and treadmill performance time were moderately enhanced (7,5% and 8% respectively; P less than 0,05) by the initial 10-week basic training programme. Further analysis of the results showed this endurance-training effect to be limited to recruits of average and, in particular, below-average fitness. The salutary effect of basic training on fitness levels was, however, transient, the values on completion of 1 year's military training being unaltered from those before conscription. This preliminary assessment of the SADF physical training programme suggests a need for the introduction of changes during and, in particular, after basic training.

The South African Defence Force physical training programme. Part II. Effect of 1 year's military training on muscular strength, power, power-endurance, speed and flexibility.

The effect of the South African Defence Force (SADF) military training on recruits' muscular strength, power, power-endurance, speed and flexibility was investigated. In the entire study group, a significant enhancement by basic training was observed for the isokinetic muscular strength of the right elbow extensors alone (17% increase; P less than 0,05). Stratification of training responses on the basis of initial fitness levels revealed significant improvements with basic training for all measures of muscular strength, power, power-endurance and speed, but not flexibility, in the below-average fitness recruit. For all variables the training effect was transient and values documented on completion of 1 year's military training differed insignificantly from those recorded before conscription. In contrast, with the exception of elbow extensor muscular strength, fitness levels of the average and above-average recruits were not increased by basic training. While further research to assess physical requirements of various military work and emergency situations is needed to evaluate the desirability of this observed selective enhancement of recruit fitness levels during basic training, it is evident that greater emphasis should be placed on flexibility training, and physical conditioning after basic training.

The South African Defence Force physical training programme. Part III. Exertion-related injuries sustained at an SADF basic training centre.

The incidence and nature of exertion-related injuries were studied at a South African Defence Force basic training centre. A total of 404 separate injuries were sustained by 359 of 947 recruits during the 10-week basic training cycle. Of these injuries, 18,3% were sustained with (group 1) and 81,7% without (group 2) an obvious sudden precipitating event. Exertion-related injuries were responsible for a loss of 2711 recruit-days of basic training. While the knee sustained the largest number of group 2 injuries, lower leg trauma resulted in the greatest loss of basic training time. Forty-two separate radio-graphically confirmed stress fractures were incurred by 39 recruits, an incidence of 4,12%, which is considerably higher than that in the US Army. These data leave little doubt that the present training programme is costly in terms of training-time lost and may prevent large numbers of recruits from deriving the optimum conditioning benefits.

Effect of beta1 selective adrenoceptor blockade on physiological response to exercise.

The effect of the beta1 selective adrenoceptor blocker, atenolol, on the physiological response to exercise was studied in 12 healthy young men. Oral atenolol (100 mg) and placebo were administered in a randomised double blind crossover fashion an hour and a half before an intermittent multistage cycle ergometer exercise test. At maximal effort oxygen consumption, pulmonary ventilation, carbon dioxide output, and respiratory exchange ratio were not modified by atenolol. In contrast, maximal heart rate and performance time were significantly reduced after atenolol. Nevertheless, because the relation of percentage of maximal oxygen consumption to percentage of maximal heart rate was not changed by atenolol both the absolute and relative oxygen consumption corresponding to 70% and 85% of the maximal heart rate remained unaltered. These data suggest that recommendations of exercise intensity may be determined on the basis of a calculated percentage of the predetermined maximal heart rate in persons without symptomatic coronary heart disease receiving beta1 selective adrenoceptor blockers.

Thermoregulatory responses to weight training.

Thermoregulatory responses of eight healthy males (age 25.5 +/- 4.5 yrs) were studied during weight training comprising 3 sets of 15 repetitions of 9 exercises performed at a work cadence of 15 repetitions.min-1 with 1-min recovery intervals. The load for each exercise was increased from 50% of the 15-repetition maximum for the first set to 75% and 100% for the second and third sets, respectively. The thermoregulatory response was characterized by only moderate sweat rates (0.69 +/- 0.18 l.h-1) and rectal temperature rises (1.3 degree +/- 0.4 degree C, P less than 0.001), suggesting that dehydration and hyperthermia are unlikely to complicate weight training of the format used in this study. Despite a considerable lactic acidosis, small elevations in serum levels of aspartate aminotransferase and lactate dehydrogenase occurred, the core temperature rise being inadequate for significant cellular damage to ensue. Serum electrolyte levels measured immediately and 24 h post-exercise indicated that electrolyte supplementation is unlikely to be of benefit. Weight training induced a marked reduction of plasma volume (11.8% +/- 3.7%, P less than 0.001) in the presence of a minor water deficit (0.8% +/- 0.23%) and an O2 consumption of 32% +/- 8% of the predetermined treadmill exercise maximal O2 consumption. This finding suggests that exercise intensity as assessed by percentage maximal voluntary contraction rather than percentage maximal O2 consumption might determine the degree of hemoconcentration encountered during exercise.

Effect of beta-adrenoceptor blockade on thermoregulation during prolonged exercise.

The effect of clinically used equipotent doses of nonselective (beta 1/beta 2; propranolol) and selective (beta 1; atenolol) beta-adrenoceptor blockers on thermoregulation was studied during prolonged exercise in the heat. Oral propranolol (160 mg/day), atenolol (100 mg/day) or matching placebo were taken for 6 days each by 11 healthy young adult caucasian males. Subjects participated in 2 h of block-stepping at a work rate of 54 W in an environmental chamber with a temperature of 33.2 +/- 0.3 degree C dry bulb and 31.7 /+- 0.3 degree C wet bulb, 2 h after ingestion of the final dose of each drug. Both active agents produced similar marked (P less than 0.001) increases in subjective perception of effort, the mechanism of which was not immediately evident from changes in serum electrolytes, blood glucose, blood lactate, or ventilatory parameters. Propranolol did, however, cause a greater rise in serum K+ than placebo (P less than 0.02) and atenolol (P = NS) after exercise. Although rectal and mean skin temperatures were insignificantly altered by beta-adrenoceptor blockade, an increased total sweat production was noted with propranolol (P less than 0.01 vs. placebo) and to a lesser degree atenolol (P = NS vs. placebo) therapy. Analysis of the time course of sweat production showed the propranolol-mediated enhancement of sweating to ensue largely during the initial hour of block-stepping and to be transient in nature. The scientific and clinical implications of this observation will be dependent upon the precise underlying mechanism, a factor not identified by the present study.

Assessment of a geriatric exercise programme using ambulatory electrocardiography.

The purpose of this study was to assess the efficacy as well as the immediate possible cardiovascular risk of a geriatric exercise programme, administered without prior medical screening or evaluation of the exercise capacity of the participants, in improving cardiorespiratory fitness. Ambulatory electrocardiography performed during exercise on 6 randomly selected male participants in a physiotherapist-controlled geriatric exercise programme revealed heart rates of 72-97/min, values unlikely to produce significant improvements in cardiorespiratory fitness. This low-intensity exercise session did not induce any ischaemic ST-segment displacements, or arrhythmias displaying the generally accepted criteria for premonitory arrhythmias known to precede the development of ventricular fibrillation. However, subsequent stress testing, performed at the lower threshold intensity of exercise needed to elicit a significant physiological training effect, resulted in an adverse cardiac response in 3 subjects, of whom 2 were asymptomatic. We conclude that the geriatric exercise programme under investigation would be unlikely to result in improved cardiorespiratory fitness in the majority of participants, but if such a programme is to be implemented in a safe manner in a geriatric population, prior medical screening including exercise testing is mandatory.

Improved exercise ventilatory responses after training in coronary heart disease during long-term beta-adrenergic blockade.

Exercise ventilatory responses of 7 men with well-documented myocardial infarction receiving long-term beta-adrenergic blockade were studied before and after 4 months of endurance training. Observations were obtained during graded levels of upright treadmill exercise continued until 85% of the predetermined symptom-limited heart rate (working heart frequency limit). This submaximal testing procedure revealed a significant slowing of the heart rate (p less than 0.005) together with an increased oxygen pulse (p less than 0.05) after training, for what was previously a maximal work load for the working heart frequency limit. In addition, all patients achieved an increased exercise duration and work load, accompanied by significant increases in maximal oxygen uptake (p less than 0.01), oxygen pulse (p less than 0.025), and respiratory exchange ratio, for their working heart frequency limit after exercise conditioning. These results show that prolonged physical training results in physiologic adaptations to cardiac rehabilitation in the presence of long-term beta-adrenergic blockade.

Effects of caffeine ingestion on thermoregulatory and myocardial function during endurance performance.

The effect of caffeine administration on thermoregulatory and myocardial function during endurance performance was studied. A caffeine solution (250 ml; 5 mg caffeine/kg body weight) ingested 1 hour prior to 2 hours of running by 5 subjects was shown to have no significant effect on sweat loss, water deficit, percentage change in plasma volume, final rectal temperature and serum electrolyte levels, as compared with a similar control group who were given a caffeine-free drink. The rectal temperatures in both groups did, however, reach levels known to be associated with heatstroke despite a recommended regimen of fluid replacement. No pathological electrocardiographic changes occurred in either group. It is therefore concluded that the use of caffeine for ergogenic purposes by young athletes is a relatively safe procedure.