December 19, 2007
Filed under: Aerobic, Physical — arlene @ 12:08 am
Rapid air travel across several time zones exposes the traveller to a shift in the internal biological clock. The result is a transient desynchronisation of rhythm, lasting until the biological rhythms adjust to the new environmental conditions. The subjective symptoms usually associated include sleep disorders, difficulties with concentrating, irritability, depression, disorientation, distorted estimation of time, space and distance, lightheadedness, loss of appetite, and gastrointestinal disturbances.
Air crews report sleep disturbances in about 60-70% of cases on the first night after crossing a time zone, which is reduced to 30% on the third day; loss of sleep amounts to as much as 5 or 6 hours per night flight. Moreover, female flight attendants experience more irregular menstrual cycles. It is well known that westward flights (characterised by a phase delay) are followed by faster recovery and resynchronisation than eastward flights (phase advance), and sleep quality decreases particularly after eastward flights. Klein and Wegmann calculated that 3 days were needed to resynchronise psychomotor performance rhythms after a westward flight from Germany to the United States, whereas 8 days were required for the reverse direction.
After a time zone crossing of several hours you can recover day by day. After a westward flight the mean re- entrainment shift rate is about 92/min/day, and only 57/min/day after eastward flights. However, there is a considerable variation in the rate of readaptation between individuals for a given rhythm and between rhythms in a given individual. About 30% of trans- meridian travellers have little or no difficulty adjusting to the temporary circadian desynchronisation and have no symptoms, but another 30% do not adjust well at all.
Symptoms are commonly reported during the 48 hours immediately after a flight, and the more time zones that have been traversed, the longer is the period of recovery, although the relation is not linear. Individual factors associated with widely differing rates of rhythmic readaptation are direction of flight, synchroniser strength, rhythm stability, personality chronotype, rhythm amplitude, behavioural traits, and sleep habits. Thus, for example, evening type people are less sensitive than morning types, people with low amplitudes in body temperature seem to be less resistant to phase shift than individuals with large circadian amplitudes, and older travellers suffer more than younger ones.” It has also been reported that re-entrainment after transmeridian flights is more rapid in summer than in winter, possibly because the longer day permits greater exposure to natural daylight.
Filed under: Man, Physical, Programs, Trainer — arlene @ 12:06 am
1) Ventricular fibrillation/rnyocardial infarction
The most serious complications of exercise treatment for cardiac patients are acute infarction and sudden death, usually from ventricular fibrillation. These are most likely in patients with exercise induced ischaemia and those with severe ventricular damage. Ventricular fibrillation is 100 times more likely during exercise than at other times but is still very rare during supervised exercise rehabilitation, between once per 33 000 patient hours’ and once per 112 000 patient hours of exercise.”‘ Myocardial Infarction is even rarer during the rehabilitation programme.
2) Angina pectoris (more…)
Filed under: Mental — arlene @ 12:03 am
- Chronobiology investigates the rhythmic patterns in biological phenomena. Biological rhythms are endogenous and inherited with the DNA, but can be adjusted (though not imposed) by environmental synchronising cues
- Biological rhythms may show a wide range of period. The most extensively studied are circadian rhythms (from the Latin circa diem meaning about 24 hours), but both ultradian (<24 hours) and infradian (>24 hours, for example, circaseptan, circannual) also exist
- Many physiological mechanisms, each of them contributing to overall athletic performance, show a peculiar circadian pattern. Body temperature starts rising before waking, reaches a peak in the afternoon, then falls during sleep. An afternoon peak is also shown for heart rate, stroke volume, cardiac output, blood flow, and arterial blood pressure
- As a consequence, most components of sports performance show a rhythmic variation during the day, characterised by an afternoon-early evening peak. This is true for reaction time, isometric hand grip strength, elbow flexion and back strength, and long term memory recall. However, other aspects of performance, for example, mental arithmetic and short term memory peak in the early morning, so probably favouring sports demanding accuracy
- Circadian oscillation in biological parameters may condition one’s personality “chronotype”. In fact, both morning (“larks”) and evening (“owls”) type persons exist. The former get up and perform well early but must go to bed early. The latter wake up late and can retire late. All intermediate aspects, of course, are possible
December 18, 2007
Filed under: Man, Women — arlene @ 11:59 pm
In many situations it is not uncommon to consume solid food between exercise bouts, and indeed in most situations it probably should be encouraged. We undertook a further study in which eight volunteers (five men, three women) dehydrated by 2.l% of their body mass by exercising in the heat and then, over a 60 minute period starting 30 minutes after the end of exercise, consumed either a solid meal plus virtually electrolyte free flavoured water or a commercially available sports drink; the volume of fluid contained within the meal plus water was the same as the volume of sports drink consumed. (more…)
Filed under: Diet, Physical — arlene @ 11:57 pm
Some aspects of chronobiology are important to physical performance—for example, the normal cyclic variation observed in the physiological mechanisms that contribute to overall athletic performance, the effect of abnormal rhythmicity or desynchronisation on athletic performance, and the alleviating countermeasures.
Human circadian rhythms at rest
1. Body temperature
Body temperature starts to rise before waking, reaches a peak at
about 1800 hours, then falls during sleep with a nadir at around 0400 hours; an amplitude of 0.4-0.5°C is seen in young adults.” The circadian rhythm of body temperature is mainly the result of fluctuations in heat loss mechanisms rather than heat production,” maybe with the intervention of noradrenergic peaks.
2. Heart rate, blood pressure, and ventilation (more…)
Filed under: Physical — arlene @ 11:55 pm
- Exercise addiction, while not fully understood, probably depends on the complex interplay between both psychosocial and physiological factors
- While exercise regimens may be able to play a positive part in relation to certain psychological disorders, the type and duration of the most effective exercise programmes remains to be determined
- There is a need for large scale, multivariate, experimental research to clarify this relation and to begin to understand underlying psychological and physiological mechanisms
- Comprehensive theoretical explanations of the relation between exercise and psychological health must be able to accommodate multiple perspectives taken from a range of disciplines The role that general practitioners have and can have as promoters and prescribers of exercise is an issue that should be afforded immediate priority
Filed under: Aerobic, Mental, Muscle, Trainer — arlene @ 11:52 pm
For more in depth information readers should read the excellent review by Atkinson and Reilly.’ We will summarise the data from it. Although considerations such as environmental influences, temperature, meteorological conditions, and scheduled time of events make generalisation difficult, most components of sports performance exhibit a rhythmic variation during the day, with a peak in the early evening. The time of day is characterised by peaks in reaction time, isometric hand grip strength, elbow flexion strength, back strength, total work performed in high-intensity constant work-rate exercise, and lactate production” and lowest levels of joint stiffness and pain perception. When subjects are free to choose their submaximal work-rate during exercise of less than 40 minutes duration, higher work rates are achieved in the early evening without any change in the perception of effort.” Moreover, in young adults the mean work rate over 80 minutes of exercise was found to be higher in the afternoon than in the morning. Improvements in muscle strength after training sessions scheduled in the evening have been found to be 20% higher than those after training carried out in the morning. In untrained male volunteers aerobic exercise performance did not show variations during the time frame within which exercise is normally conducted, although some physiologal responses to exercise did. (more…)
Filed under: Drugs, Mental, Muscle, Physical, Trainer — arlene @ 11:51 pm
1. Increased physical fitness
Community surveys have shown that the general level of fitness in this country is ‘deplorably low’ and patients who suffer coronary problems have even lower levels. The improvements achieved by physical training as described above are of obvious benefit to the daily activities of cardiac patients. The energy costs of a wide variety of activities both at work and leisure have been estimated,”” and can theoretically allow prediction of the ability of cardiac patients to perform such tasks. In the United Kingdom the ability to regain a licence to drive a large goods or passenger carrying vehicle depends on the completion of 9 minutes of the Bruce protocol treadmill test, a feat that may only be possible after exercise training.
One group that may have most to gain is patients with cardiac failure.
Exercise in heart failure (more…)
December 7, 2007
Filed under: Man, Muscle, Physical, Trainer, Women — arlene @ 1:37 am
Examination of the way physical activity has been measured and reported in studies such as the Harvard alumni study’ and the multiple risk factor intervention trial‘ leads to the possibility that benefits were mainly linked to the total amount of energy expended. This does not preclude the possibility of additional benefit from sustained activity; indeed Paffenbarger has been quoted as saying that, among men who expended the same amount of energy weekly, those who performed some form of sustained exercise had significantly lower death and heart attack rates than those who did not’ although I am not aware of any published data on this.
It is, however, plausible that at least some of the benefit of activity is achieved through the associated increases in energy expenditure.
Recently, the concept of metabolic fitness has been introduced’ in an attempt to highlight the multiple metabolic benefits of considerable amounts of low intensity exercise taken on an almost daily basis and which have been shown experimentally to be independent of changes in cardiorespiratory fitness as assessed by VO2MAx. The metabolic variables in question include insulin sensitivity, low concentrations of plasma TAG and high plasma Concentrations of HDL cholesterol. Changes in these have been closely associated with decreases in body fatness, particularly loss of abdominal fat,’ but low intensity training in the absence of fat loss can also stimulate changes in lipoprotein metabolism and insulin sensitivity.” (more…)
Filed under: Diet, Drugs, Mental, Physical, Programs — arlene @ 1:36 am
As obligatory urine losses persist even in the dehydrated state, it is clear that any drink consumed after exercise-induced or thermal sweating must be consumed in a volume greater than the volume of sweat that has been lost. To investigate the influence of drink volume on rehydration effectiveness, 12 male volunteers performed intermittent exercise in the heat to induce a level of dehydration equivalent to a mean of 2.06% of their initial body mass. (more…)
Filed under: Aerobic, Mental, Physical — arlene @ 1:33 am
A poor competitive performance may result when an athlete does not take into consideration his or her circadian performance profile, as an athletic task undertaken several hours before or after the circadian peak “window” will potentially be performed with less than optimal efficiency. Taking circadian rhythms into consideration can produce major benefits in tasks involving endurance, mental function, physical strength, and others. Selection of the best circadian time can result in as much as a 10% increase in athletic performance. A 10% decrement in peak performance can be compared with a performance after less than 3 hours of sleep, after drinking the legal limit of alcohol, or after taking barbiturates. (more…)
Filed under: Drugs, Gym, Insurance, Man, Physical, Trainer — arlene @ 1:31 am
A study was undertaken to examine the effect of the sodium content of drinks on the rehydration process after exercise-induced dehydration equivalent to l.9% of body mass of six fasted but euhydrated men.’ After dehydration they consumed drinks with sodium concentrations of l, 25, 50, and 102 mmol/l over a 60 minute period beginning 40 minutes after the end of exercise; the volume consumed was l.5 times their mass loss by dehydration which amounted to about 2 litres in all trials.
The entire volume of urine produced over the 6 hours after the end of the drinking period was collected and measured (no other food or drink was consumed after the rehydration period). The volume of urine produced was influenced by the quantity of sodium consumed, such that it was greatest when the 1 mmol/l drink was consumed and least when the 102 mmol/l drink was consumed (fig 14.l). The sweat secreted during the exercise was collected and the sodium content measured; the mean (SD) concentration was 49.2 (18.5) mmol/1. Calculations of whole body sodium balance can be made, taking the pre-exercise values as the zero point (fig 14.2); the results clearly show that there is a strong relation between the sodium content of the ingested fluid and its ability to restore water balance. (more…)
Filed under: Aerobic, Man, Physical, Trainer — arlene @ 1:29 am
For exercise, the dose involves frequency, intensity, and duration.
1. Frequency
The American Heart Association recommends for cardiac Patients a frequency of between two and four times a week,’ although there is little evidence to support this figure. Most trials of physical training have used three or four weekly sessions. It has been shown that, for early postinfarction exercise training, a programme of two sessions a week is as effective as three. Increasing from three to five sessions does not seem to produce much further benefit for normal middle aged men. (more…)
Filed under: Aerobic, Essays, Gym, Mental, Physical, Sex, Singles — arlene @ 1:28 am
Taken as a whole, the review posits that a range of exercise regimens may have a therapeutic role in relation to a number of psychological disorders. At the same time, the research evidence to date does not provide unqualified support for the efficacy of exercise, and enthusiasm must be tempered with an acknowledgment of the dangers associated with exercise. Certainly, the literature does not indicate that exercise should be treated as a panacea or snake-oil for psychological malaise of whatever kind. Instead, it does suggest that different forms of physical exercise may be palliative in relation to particular conditions.
Whether that exercise be non-aerobic, aerobic or anaerobic, of short, medium or long term duration, competitive or non-competitive, team or individual, single or multi-session, is not always clear but there are suggestions that different psychological conditions respond differentially to alternative exercise regimens and recent attempts to develop taxonomies of physical activity and mental health may offer a realistic starting point in attempting to draw together some of the diverse recommendations. (more…)
Filed under: Family, Man, Mental, Physical, Women — arlene @ 1:27 am
This is a meditation exercise we have both found very useful. It was devised by a friend. Try it and adapt it for your own purposes, or find your own from a book, tape or seminar.
- Begin by becoming aware of your breathing.
- Do not interfere with your breath, just watch it – the rise and fall, the ebb and flow…
- Listen to the sounds near and far; become aware of the traffic noise, birds calling, wind in the trees, a dog barking in the distance…
- Then move outside yourself; look back at yourself sitting there.
- Gradually move your awareness outside your home, so you can see your house, your street, your town or city.
- Keep moving your awareness so that you are now looking down on your province, your state, your country.
- Now visualise your country as part of the Earth as you travel towards the stars.
- Once you are able to ’see’ the Earth as part of the solar system and look down on the Earth, send love from your heart back to it.
- Feel the love pouring through you like the golden rays of the sun.
- Allow yourself to dissolve and rest in the warmth of the sun.
11. Be still. Just be.
December 4, 2007
Filed under: Man, Physical, Women — arlene @ 12:58 am
Some investigators have boldly claimed that hypertrophic cardiomyopathy is the commonest cause of death in young athletes. In fact, extreme forms of “athletes heart” are quite uncommon, even in highly conditioned athletes, and the total number of exercise related deaths is very low (for example, around 100 per year in the United States). Most incidents occur in the coronary-prone age range and are probably due to coronary atherosclerosis rather than ventricular hypertrophy. A computerised search of the literature covering a 50 year period unearthed a total of four likely cases of hypertrophic cardiomyopathy in athletes who were under the age of 40 years! (more…)
Filed under: Essays, Man, Physical, Women — arlene @ 12:54 am
Ilk Mechanical loading is an important determinant of bone mass and architecture’ and the influence of increased physical activity on bone has been much studied. This is one area where the accumulation of exercise throughout the day must, theoretically, be an effective pattern. An osteogenic stimulus arises when bone is exposed to unusual dynamic strain distribution. This effect is quickly “saturated”, however, so that there is little extra stimulus to bone formation from high numbers of load cycles. The relevance of this finding is that the structural competence of bone can be maintained by comparatively infrequent loading events and does not require long periods of repetitive activity.’ This thinking fits well with findings of increased bone mineral density in premenopausal women after a daily exercise regimen of 50 vertical jumps.’ If strain magnitude and strain nature are the determinants of the osteogenic response to exercise, then several brief periods during a day of high impact exercises will in fact be more effective than long periods of endurance-type exercise where the applied loads are typically low. (more…)
Filed under: Muscle, Trainer — arlene @ 12:51 am
One of the main reasons for fear of hypertrophic cardiomyopathy is that occasionally a young endurance athlete dies on the sports.
It is reasoned that cardiac hypertrophy provides an explanation of such deaths, and that the condition should have been detected by a careful preparticipation examination, despite growing evidence that attempts at preparticipation screening are not cost-effective. (more…)
Filed under: Physical — arlene @ 12:50 am
- There is controversy in the literature about the effects of exercise on testosterone concentrations. Conflicting results may be explained by differences in the intensity and duration of the activity and physical characteristics of the individual including age and fitness level. Methodology issues including the study design and sampling, and analysing techniques for testosterone concentrations may also influence the results. (more…)
Filed under: Aerobic, Man, Physical, Trainer, Women — arlene @ 12:48 am
The idea that sporadic bouts of activity will be an adequate stimulus to health benefits comes also from studies that have systematically compared the effects of shorter bouts of activity spread throughout the day with those of longer bouts. Two studies are consistently cited in the statements of expert panels’ -namely those of deBusk and colleagues’ and Ebisu. In the former, 36 sedentary middle aged men performed either one 30 minute session of jogging or three 10 minute sessions on 5 days a week for 8 weeks; the intensity of exercise was 65% to 75% of maximum heart rate (equivalent to 55% to 65% of VO2MAx). Men were allocated randomly to the different patterns of exercise but there was no control group. Although both groups of joggers showed similar decreases in heart rate during a standard submaximal treadmill test, the increase in VO2MAx was significantly greater for the long bout group (4.4 ml/kg/min, 13.9%) than for the short bout similar group (2.5 ml/kg/min, 7.6%). Decreases in body mass were (l.75 kg and l.79 kg, respectively). (more…)
