Planned Structure Physical Activity Physical Education Essay
Exercise is a specific type of planned structure physical activity done to improve or maintain physical fitness.(2) Physical fitness is comprised of multiple attributes related to the ability to perform physical activity. Some of the attributes include as varied parameters as cardiorespiratory fitness, regional body fat distribution, body mass index, muscular strength, muscular endurance, flexibility, power, reaction time, speed, blood sugar levels and blood lipid levels.(2) Various exercise training regimens have been studied to see their effect on the various components of fitness. VO2max is the best indicator of cardiorespiratory fitness.(63) Aerobic training has been shown to improve cardiorespiratory fitness. Rather than have multiple exercise regimens targeted at improving each attribute of physical fitness, a better strategy would be to do a combination exercise that will improve as many attributes of fitness as possible. Also the types of training that have been studied extensively, often requires specialized equipment that may not be available to the general population. Martial arts are a unique exercise regimen that is generally available and does not require any specialized equipment.
Many studies have been conducted that look at the effect of Kungfu training on different components of physical fitness. This is the first study comparing cardiac autonomic parameters and physical fitness measures in Kungfu practitioners and controls of similar physical activity level who do not practice any other form of martial art. Previous studies that specifically looked at cardiorespiratory fitness have compared Kungfu subjects with controls who practiced an alternate martial art. (12,49)
Both Tsang et al and Schneider et al have compared Kungfu training with tai chi training.
Tai chi is a soft martial art which incorporates breathing exercises and meditation with less emphasis on power. (45) This may have acted as a confounder. The intensity of Kungfu sessions are higher with an oxygen consumption of 52.4% of VO2max and achieving a heart rate of 70.5 � 89 % of HRmax, while tai chi practice reaches 36.4% of VO2max and 59.8% of HRmax.(13,49). Elderly subjects who have been trained in tai chi for a year have been found to have significantly better aerobic capacity than sedentary controls while having similar aerobic capacity as brisk walking controls.
In the current study, to avoid this error all alternate martial artists, those performing other types of breathing exercise and meditation were excluded.
Tsang et al compared the effect of six months training in Kungfu in obese adolescents in a randomized control setting comparing with tai chi training assuming it to be a sham exercise.(12)
Both Kungfu and tai chi groups showed significant improvement in absolute upper and lower body strength, and upper body muscle endurance, without any difference between groups. Because of the low baseline levels in obese sedentary subjects any form of exercise may show a significant improvement. Selection of sedentary controls is a selection bias. To avoid this selection bias the current study compared subjects of similar physical activity levels.
Tsang et al showed significant improvement in submaximal fitness in Kungfu group while the peak aerobic fitness was same in Kungfu and tai chi group which is consistent with the results of the current study which shows no significant difference in physical fitness parameters between Kungfu group and controls of similar physical activity level. The peak fitness did not alter with six months martial arts training in both groups.
Tsang et al showed that the Kungfu group had significantly greater lower body muscle endurance and upper body muscle velocity than tai chi group. Also the upper body peak velocity significantly declined over six months in the tai chi group. This may be due to the focus of Kungfu on power and speed while tai chi focuses on slow meditative movements.
Schneider and Leung also studied the effect of Kungfu training on cardiorespiratory fitness by using a tai chi group as a control. There was no significant difference in VO2max and HRmax between the groups. The current study has shown that HRmax is lower in HRmax in Kungfu subjects (K = 182.8) when compared to control subjects (C = 185.6). The lack of difference in HRmax between Kungfu and tai chi subjects in study by Schneider and Leung suggest the possibility that the decrease in HRmax may be due to the components of martial arts training.
Various studies have shown that both anaerobic and aerobic exercise training can decrease maximal heart rate achieved in maximal exercise testing. (81�83) Zavorsky has shown that aerobic training and detraining can vary the HRmax by 3 � 7%.(83) The reason for this decreased HRmax is not clear but some of the proposed mechanisms are plasma volume expansion, enhanced baroreflex function, alteration of SA nodal activity and change in sympathetic receptor profile produced by regular exercise. (83)
Was the significant decrease of HRmax in Kungfu due to any underperformance by Kungfu subjects? The question is answered by the fact that the work intensity at maximal level was the same in both groups (p>0.05). The Kungfu group has reached the same work intensity with a lower HRmax. Showing better work capacity for the same level of workload. This lower heart rate for a work load may have been the reason for significantly higher submaximal fitness shown by Tsang et al in Kungfu group.
Effect of Kungfu training on the other parameters of fitness has been studied by other groups. Six month Kungfu training when compared to tai chi training in obese adolescents was found to have no significant difference in body composition parameters, bone mineral density, blood lipids, blood glucose and HbA1c between the martial arts groups. (43,44) Kungfu trained subjects had significantly better total auditory reaction times, movement time, hand speed, effective mass, leg muscle strength than sedentary controls while there was no significant difference in trunk muscle strength.(45,84) Jones and Unnithan compared experts in Kungfu to novices and found that while doing forms and punching experts, worked at a significantly lower percentage of VO2max showing a better aerobic economy. The exercise intensity elicited by Kungfu protocols were found to be in the cardiovascular training zone.
No other group has studied the effect of Kungfu training on cardiac autonomic control. The significant increase in SDNN in Kungfu subjects (K = 106.7) over controls (C = 83.4) reflects an increase in total Heart rate variability in Kungfu trained subjects when compared to subjects with same physical activity level.
RMSSD which is an index of vagal activity was significantly higher in Kungfu subjects (K = 105.5) than in controls (C = 77.2). This indicates higher parasympathetic modulations in Kungfu trained subjects. While pNN50 and HFnu both are alternate indices of parasympathetic activity, they were not significantly different between the groups. This seems contradictory but RMSSD is reported to be a better parameter than pNN50 as it is not influenced by heart rate trends and is independent of mean heart rate and has overall better statistical properties.(58,85) so the significant RMSSD change should be considered to be more valid.
Which component of Kungfu training is responsible for this significant increase in cardiac autonomic modulations?
Kungfu is a combination of aerobic and anaerobic exercise interspersed with frequent breathing exercises with a short period of meditation at the beginning and end. Meditation and breathing maneuvers have been shown to improve cardiac autonomic modulations. (22) But there is only a short period of meditation. Breathing exercise called �breath out maneuver� is done multiple times during a Kungfu class, whenever the subjects are out of breath. During the latter half of class as students are more tired, �breath out� maneuver is done once every couple of minutes.
To understand the physiological effect of �breath out� maneuver two subjects were asked to do the breath out maneuver and the heart rate and respiration changes were examined and analyzed. �Breath out� maneuver consists of a slow forced expiration in the standing position with abdominal muscles contracted. The arms move forward while air is slowly blown out forcibly against a partially closed glottis. During the expiration phase of the maneuver the heart rate was found to rise slowly. After cessation of maneuver there was a sudden bradycardia. Valsalva maneuver is forced expiration against resistance. In Valsalva maneuver also a similar reflex bradycardia is observed. The heart rate responses to �breath out� and valsalva maneuvers are compared in figure 9.
The breath out maneuver may be a modified form of Valsalva maneuver. Does this use of modified Valsalva maneuver have any positive or detrimental effect on cardiac autonomic status? This question is answered by our study. Let us look at the Valsalva maneuver.
Valsalva maneuver was originally described by Antonio Valsalva in 1704 in his Latin treatise �De aure humana tractatus�.(86) Valsalva maneuver is defined as forceful expiration against a closed glottis or with an open glottis against an expiratory pressure.(87�89) Valsalva maneuver may lead to medical complications like valsalva retinopathy and surgical emphysema.(86) Valsalva maneuvers are performed often, both voluntarily and involuntarily during daily life when coughing, straining and lifting weights. So it is essential to understand the underlying physiology.
Valsalva maneuver has four physiological phases:
Phase I - Onset of blowing. In this phase forced expiration raises intrathoracic pressure pressing on aorta leading to raised MAP. (87�89)
Phase II - Continued expiration. Due to continually raised intrathoracic pressure there is a fall in venous return and consecutively there is decreased atrial filling leading to decreased cardiac output and BP falls. Fall in BP causes unloading of the baroreceptors located in the carotid sinus and aortic arch caused decreased impulses in glossopharyngeal and vagal afferents to the nucleus of the tractus solitarius. Sympathetic outflow is stimulated via centers in the medulla leading to peripheral vasoconstriction and increase in cardiac output and hence BP. Vagal neurons of the nucleus ambiguus are inhibited leading to a rise in heart rate. (87�89)
Phase III - Release of strain. After release of expiratory pressure Intrathoracic pressure becomes negative leading to release of pressure on the arterial tree causing drop in BP and entry of blood into the pulmonary vasculature. (87�89)
Phase IV - Recovery. As cardiac output becomes normal, the persistently increased sympathetic tone and systemic vascular resistance leads to overshoot of BP. A reflex bradycardia results due to stimulation of arterial baroreceptors, and later both BP and heart rate return to baseline values. (87�89)
The tachycardia in phase II and the bradycardia in phase IV are used as indexes of cardiovagal integrity. The hypertensive response in phase IV and BP recovery in phase II and are used as indexes of baroreceptor mediated sympathetic integrity .Valsalva maneuver can be used to noninvasively assess baroreceptor sensitivity. (87�89)
What is the consequence of this repeated stimulation of baroreflex in Kungfu subjects? The breath out maneuver is done in the standing position. In standing position there is increased total peripheral resistance, heart rate and while doing valsalva there is an increased fall of BP in phase II and overshoot in phase IV.(89) Baroreflex gain is found to be reduced in standing valsalva when compared to supine position but even with lower gain the repeated �breath out� maneuvers may increase the baroreceptor sensitivity by repeated stimulation of the baroreflex. Tai Chi training has been shown to significantly improve baroreflex sensitivity. (90) Aerobic training also increases baroreflex sensitivity.(91)
This improvement in cardiac autonomic modulations and specifically vagal modulations and the lowering of HRmax caused by Kungfu training may be due to this increased baroreceptor sensitivity.
Tai chi training, similarly, has been shown to significantly increase overall cardiac autonomic modulations and specifically increase vagal tone and modulations by decreasing heart rate, increasing total variability, increasing SDNN and increasing HFnu. (92�94)
Whether modified Valsalva maneuver should be included in other fitness regimens needs more research.
In conclusion, subjects with Kungfu training had greater total heart rate variability and cardiac vagal modulations than control subjects with similar physical activity levels. This augmented cardiac autonomic control observed in Kungfu subjects may be attributable to the regular practice of �breath out maneuvers�, which form an intrinsic part of the exercise protocol of Kungfu training.
Direct Assessment of VO2max was not possible due to unavailability of breath analyzing equipment. Suitable indirect methods were used to assess it. If such equipment is available, an individualized ramp protocol targeted at 9 minutes to reach exercise time could have been used. A fixed ramp protocol was used as the treadmill time duration itself was a parameter for indirectly assessing VO2max.
SUMMARY AND CONCLUSIONS
SUMMARY AND CONCLUSIONS
Higher physical fitness appears to prolong life. (4�6) To attain, maintain and improve fitness, one mode of physical activity used is exercise. Exercise consists of planned, structured, and repetitive bodily movement. (2) Martial arts are methods of combat that have been altered into exercises. (7) Kung Fu is a generic term used for Chinese martial arts. (8) Kungfu is an unique which incorporates a mixed anaerobic and aerobic exercise regimen which is combined with breathing exercises and meditation. (8�11) No studies have been done on the effect of Kung Fu training on cardiac autonomic function. This study looked at the effect of Kungfu training on cardiac autonomic status and physical fitness.
The cardiac autonomic effects of endurance and strength training have been studied separately and documented. (15) But there are no studies on combined aerobic and anaerobic training programs on cardiac autonomic status. Further, breathing exercises and meditation have been shown to affect cardiac autonomic status by lowering heart rate, modifying heart rate variability and decreasing blood pressure. (21,22) Kung Fu involves aerobic and anaerobic training, along with meditation and breathing exercises. There are no studies reporting the combined effects of all these maneuvers on physical fitness and cardiac autonomic control.
Twenty Martial artists who have practiced Kungfu for over a year were recruited and compared with twenty normal subjects of similar age, BMI and physical activity. Cardiac autonomic status and fitness level was compared between these groups.
The cardiac autonomic function tests administered were heart rate variability analysis, deep breathing test, orthostatic challenge test, Valsalva maneuver and maximal hand grip test. The tests were conducted as per standardized published protocols. Standard indices were calculated from these tests and compared. The resting heart rate, resting blood pressure and rate pressure product were also obtained. This was followed by a maximal treadmill test.
A maximal exercise test was used to estimate VO2max indirectly. A fixed ramp protocol was used in a motor driven treadmill to administer a maximal test. Immediately after exercise, the subject rested in the supine position, during the period of recovery. The maximal heart rate achieved with maximal exercise (HRmax) and absolute heart rates at different points of recovery was obtained. The heart rate recovery (HRR) at a given point of time was computed by subtracting the absolute heart rate at that point of time from the HRmax. HRR is an index of physical fitness and a predictor of VO2max. (24) The ratio of HRmax to resting heart rate and total exercise duration was also used as predictors of VO2max. (25) The work intensity at maximal exercise was also calculated and compared. (26)
Tests revealed significantly increased SDNN and RMSSD parameters of short-term heart rate variability in Kungfu trained subjects showing improved overall autonomic modulations and vagal modulations when compared to controls,. The maximal heart rate reached with maximal exercise was significantly less in Kungfu group. Other parameters were not significantly different.
Kungfu is a unique form of exercise training which incorporates aerobic exercises, anaerobic exercises, breathing exercises and meditation. Kungfu training improved overall heart rate variability and vagal modulations and allowed the subject to do similar quantum of work at a lower heart rate than controls, as evidenced by the lower heart rate in the Kungfu group at similar maximal work intensities reached by both groups.
The breath out maneuver needs to be studied more to understand its physiological effects.
And to determine whether it needs to be added to existing sports and fitness regimens.
Effect of breathing exercise and meditation can be studied separately in a RCT setting to quantify the benefits when isolated from other forms of exercise.
The effect of combined aerobic and anaerobic exercise training on cardiac autonomic control can be studied in a randomized crossover trial setting.
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