Oxygen uptake, heart rate, and blood lactate responses during and following karate training

Abstract

Oxygen uptake, heart rate, and blood lactate responses during and following karate training. Med. Sci. Sports Exerc., Vol. 31, No. 2, pp. 342-347, 1999.

Purpose: 

The purpose of this study was to examine whether each exercise and an entire karate training session can achieve: 1) accepted training intensity thresholds for effective aerobic capacity training, 2) energy expenditure (EE) thresholds for total body mass and fat weight loss, and 3) elevation in excess postexercise oxygen consumption (EPOC).

Methods: 

We investigated physiological responses during five types of karate training: basic techniques without (S-Basics) and with (M-Basics) movements, sparring techniques without (TECH I) and with (TECH II) an opponent, and kata.

Results: 

The mean percent of maximal oxygen uptake (%V̇O_2max) and HR (%HR_max) for S-Basics were below the accepted threshold (60% of HR_max or 50% of V̇O_2max) and for M-Basics, TECH I and TECH II were above the threshold for increasing V̇O_2max. For kata and the entire 70 min of karate training, the mean %HR_max were slightly above the threshold, and %V̇O_2max were slightly below the threshold. The mean EPOC measured for 5 min immediately following 70 min of karate training did not differ from the resting V̇O₂. The mean EE resulting from 70 min of karate exercise and EPOC were 2355.4 ± 316.3 kJ and 38.8 ± 32.7 kJ, respectively.

Conclusions: 

Although the training intensity of karate exercises studied was moderate and the effects of karate training on EPOC were minimal, the mean value of EE was well above the accepted threshold for total body mass and fat weight loss.

Karate training involves basics, kata, and sparring. Basic techniques such as punching, kicking, blocking, and striking are practiced either in the stationary position (S-Basics) or with body movements in various formal stances (M-Basics). Kata are set forms in pre-established sequences of defensive and offensive techniques and movements. Movements in kata are very formal, systematic, and sometimes very slow, in prescribed stances and directions. Sparring is the execution of defensive and offensive techniques while one is freely moving against an opponent. To avoid injuries, sparring is not always practiced in a regular workout. Instead, sparring techniques are performed without an opponent (TECH I) or against an opponent (TECH II). In the TECH II, there is a prearrangement between participants so that one person practices offensive and the other defensive techniques without actual contact to the body or face.

Karate training in general and karate kata in particular have been claimed to contribute to increasing general physical fitness and/or cardiovascular fitness ^(10,13,23). Some studies have reported heart rate (HR) responses, without measuring oxygen uptake (V̇O₂), of karate practitioners performing selected combination techniques in TECH I and kata ^(17,18,21) and suggested that these karate exercises can raise HR up to a level necessary for increasing cardiovascular fitness. One study measured both V̇O₂ and HR while subjects were performing advanced kata ⁽²³⁾. The results of this study suggest that advanced karate kata can be used as an effective and specific means for training aerobic capacity in karate practitioners. Shaw and Deutsch ⁽²⁰⁾, on the other hand, investigated the V̇O₂ and HR responses of beginner's kata under four different conditions: kata performed 15 times without rest at a 30- or 45-s pace or with 1 min rest between each kata at a 30- or 45-s pace. The authors reported that performing a kata at a 30-s pace without rest resulted in a V̇O₂ that was at least 50% of maximal oxygen uptake (V̇O_2max), which is the accepted threshold for increasing V̇O_2max⁽¹⁾. No other combinations of kata pace or rest time produced a V̇O₂ that was at least 50% of V̇O_2max. A review of the literature raises some arguments with the previous research. A major point of contention is that it is abnormal to perform a kata in regular practice in the same manner as was performed in these studies ^{(17,20,21,23)}. Karate practitioners usually do not perform only S-Basics, TECH I, or kata without other training exercises designed to improve V̇O_2max during a regular workout so that it is difficult to conclude that these karate exercises practiced during regular workouts can be used as an effective and specific means for training aerobic capacity in karate practitioners. Furthermore, it is noted that kata should be cautiously approached as a means to develop and maintain cardiovascular fitness because a higher HR response is elicited for a given %V̇O_2max for kata when compared with that for a cycle ergometer ⁽²³⁾ or treadmill ⁽²⁰⁾. However, none of the studies measured both V̇O₂ and HR responses in S-Basics, M-Basics, TECH I, and TECH II.

Physical exercise increases oxygen consumption during and following activity. The extra oxygen consumption following exercise has been termed "excess postexercise oxygen consumption" (EPOC). Previous studies regarding EPOC have been limited to the effects of cycle ergometer exercise ^{(2,3,9,14,15,19)}, treadmill exercise ⁽⁵⁾, or weight training ^(9,16). The effect of karate training on EPOC has never been investigated.

The purpose of this study was to investigate V̇O₂, HR, and blood lactate responses before, during, and following karate training to examine whether each exercise (S-Basics, M-Basics, TECH I, TECH II, and kata) and an entire karate training session can achieve: 1) accepted training intensity thresholds for effective aerobic capacity training, 2) energy expenditure (EE) thresholds for total body mass and fat weight loss, and 3) increased EPOC.

SUBJECTS AND METHODS

Subjects. Seven male first degree black belt practitioners who were members of the Fukuoka University Karate Club participated in this study. The mean (± SD) age, body height, weight, and karate experience of the subjects were 21.3 ± 0.5 yr, 169.9 ± 2.7 cm, 62.1 ± 5.8 kg, and 2.5 ± 0.5 yr, respectively. All subjects were smokers who smoked less than one pack a day. Karate was the only form of training at least for 2 yr for all subjects. The study protocol was approved by the Ethics Committee of the Nakamura Gakuen University and informed consent was obtained from each subject.

Maximal treadmill exercise test. Three to seven days before the experiment started each subject performed a incremental test to volitional exhaustion on a Woodway treadmill (Tokyo, Japan) using a modified Bruce protocol which consisted of 3-min work stages, starting with 1.7 mph and 0% grade, after which the treadmill speed and grade were increased according to the protocol of Bruce et al. ⁽⁷⁾. The test was conducted in air-conditioned facilities with a temperature set at 22°C. After the subjects sat comfortably for 5-10 min, resting blood lactate levels were determined. The peak values were also determined immediately after they finished the treadmill test. Shortly after 25 μL of blood was drawn from an earlobe, it was analyzed with the YSI MODEL 23 L Lactate Analyzer (Yellow Springs Instruments, Yellow Springs, OH) which was calibrated with a 5.0 mmol·L⁻¹ lactate standard (YSI 2327 Standard, Yellow Springs Instruments) between each reading. Ventilatory measurements were made by standard open-circuit calorimetry (Wyvern Software Physiologic Exercise Testing System, P.K. Morgan Instruments, Inc., Andover, MA) with 30-s sampling intervals. Subjects wore noseclips and breathed through a Hans Rudolph (Kansas, MO) low-resistance low-dead-space valve that was connected to a mixing chamber via lightweight tubing. The system was calibrated against a known mixture of gases (Sumitomo Seika, Chiba, Japan) before each experiment. The ECG, using a bipolar CM5 lead configuration, was monitored via radio telemetry (Nihon Koden, Tokyo, Japan). Exercise HR was determined during the final minute of each stage.

Testing procedure before, during, and following the karate practice. The day before each experiment breakfast and lunch were brought to each subject at 8:00 a.m. and 12:30 p.m., respectively. The subjects reported to the laboratory at 7:00 p.m. and ate supper at 8:00 p.m. The caloric content for the three meals was 12,552 kJ with 53.5%, 15.0%, and 31.5% energy derived from carbohydrate, protein, and fat, respectively. Cigarette smoking, alcohol, and beverages other than water, and physical exercise were not allowed one day before and during each experiment. The subjects slept by 11:00 p.m. and got up at 6:00 a.m. in the laboratory with the temperature set at 22°C. The subjects changed into their karate uniform after ECG surface electrodes were taped and sat quietly until 7:20 a.m. Then the subjects stretched for 10 min and practiced S-Basics for 15 min, M-Basics for 10 min, TECH I for 10 min, TECH II for 15 min, and kata for 20 min. Five minutes of rest sitting in a chair was taken between each type of exercise. Within each type of exercise, a few seconds of active standing rest was taken between executing each technique or kata.

Expired gas was collected by the Douglas bag method for the last 5 min of the rest period before exercise. During exercise, it was collected for 1 min at the 5^th and 10^th min in M-basics and TECH I, at the 5^th, 10^th, and 15^th min in S-Basics and TECH II, and at the 5^th, 10^th, 15^th, and 20^th min in kata. The average of these measurements was presented as V̇O₂ for each exercise. V̇O₂ during recovery was collected while the subject was sitting in a chair for 5 min immediately after completing the entire 70-min karate training session and 25-30 and 55-60 min during the following 4 h. The volume of gas was measured in a wet gas meter (Sinagawa Corp., Tokyo, Japan). Analyses for O₂ and CO₂ were performed on the system as described above. Total EPOC was calculated as the time integral of the difference between the resting V̇O₂ and V̇O₂ obtained during the postexercise period.

Blood lactate samples were taken in the sitting position in a chair as described above at the end of the rest period before exercise, immediately after the performance of each exercise, at the 5^th, 30^th, and 60^th min during the first hour of recovery, and at the 30^th and 60^th min during the following 3 h. The ECG as described above was monitored with a four-channel radio telemetry (Fukuda Denshi). The subjects' HR was recorded for 10 s at the end of the 10-min sitting rest and every minute thereafter. The average of HR from the 5^th to 10^th min in M-basics and TECH I (Tokyo, Japan), from the 5^th to 15^th min in S-Basics and TECH II, and from the 5^th to 20^th min in kata were presented as HR for each exercise. The percent of maximal HR (%HR_max) was calculated by dividing exercise HR by HR_max obtained from maximal treadmill exercise. RPE, using the Borg scale ⁽⁴⁾, was obtained immediately after the performance of each exercise. The EE in kilojoules was calculated from V̇O₂ and respiratory exchange ratio (RER) according to the following formula ⁽⁸⁾: EE = V̇O₂(15.480 + 5.550 RER).

Karate exercises. The series of S-Basics consisted of lower block, middle inside and outside blocks, and upper block, a middle punch, two-punch and three-punch combinations, back fist strike and swing strike performed 20 times with alternating arms; middle reverse punch performed 20 times with each arm, each leg swinging straight up as high as possible 10 times continuously; and middle front kick and roundhouse kick performed 20 times with alternating legs.

The series of M-Basics consisted of lunge punch, reverse punch, lower block-reverse punch, middle inside block-reverse punch, middle outside block-reverse punch, and upper block-reverse punch, performed 20 times with alternating sides and middle front kick, upper front kick, middle roundhouse kick, upper roundhouse kick, middle front kick-reverse punch and upper roundhouse kick-reverse punch performed 10 times with alternating sides.

The series of TECH I consisted of upper punch, middle punch, two punches, three punches, middle front kick, middle roundhouse kick, upper roundhouse kick, upper hook kick, punch-kick combinations performed 10 times with alternating sides except punch-kick combinations which were performed six times with alternating sides.

The series of TECH II consisted of 3 min of practicing favorite offensive combination techniques and defensive techniques. In the offensive combination techniques practice, the offensive side continuously executed techniques, and the other side stood still for 3 min. After 3 min, the offensive and defensive sides were changed. In the defensive combination techniques practice, the offensive side continuously attacked with upper punch, and the defensive side counter attacked or blocked and attacked with favorite techniques for 1 min. After 1 min, the offensive and defensive sides were changed. The same practice was repeated with middle punches and kicks for 1 min each.

Kata exercises consisted of five elementary kata, two advanced kata, and free practice. Five elementary kata (one to five) and two advanced kata (Saifa and Seipai) were each practiced twice, first by the leader's count and second by each subject's own speed. Each subject's favorite kata was practiced in the free practice which lasted 3 to 5 min depending on the duration of the previous kata.

The subjects were asked to practice as usual without any other directions or encouragement. This was done to avoid possible interference with their normal practice. This program was similar to the typical karate training session used at some of the civic karate schools in Japan.

Statistical analysis. Descriptive statistics included means and SD. All data were analyzed by an ANOVA with repeated measures and subsequent Scheffe test for post-hoc analysis. A P value of less than 0.05 was considered to be statistically significant.

RESULTS

The mean V̇O_2max, HR_max, peak blood lactate, and RER measured by the treadmill run were 58.6 ± 6.8 mL·kg⁻¹·min⁻¹, 198.1 ± 8.3 beats·min⁻¹, 7.9 ± 1.3 mmol·L⁻¹ and 1.10 ± 0.04, respectively.

The mean V̇O₂, %V̇O_2max, HR, and %HR_max before, during, and following karate exercises are shown in Figures 1 and 2, respectively. The mean %V̇O_2max and %HR_max for S-Basics were below the accepted threshold, and for M-Basics, TECH I and TECH II were above the threshold for increasing V̇O_2max. For kata, the mean %HR_max was slightly above the threshold, and %V̇O_2max was slightly below the threshold. Mean %V̇O_2max and %HR_max to the entire 70-min practice were 47.4 ± 5.9% and 72.6 ± 9.2%, respectively (data not shown). Although the mean EPOC measured for 5 min immediately following the entire 70-min karate training was approximately twofold higher than the resting V̇O₂, the difference was not significant.

Figure 1: -Time plot of (a) mean oxygen uptake and (b) percent of maximal oxygen uptake before, during, and following karate training. *P < 0.05 when compared with the rest.

Figure 2: -Time plot of (a) mean HR and (b) percent of maximal HR before, during, and following karate training. S-B, basic techniques practiced in the stationary position; M-B, basic techniques practiced with body movements; T-1, sparring techniques performed without an opponent; T-2, sparring techniques performed against an opponent. *P < 0.05 when compared with the rest.

The mean blood lactate, RPE, RER, and EE before, during, and following karate exercises are shown in Table 1. The blood lactate responses to the five types of karate exercises were moderate, ranging from 1.4 ± 0.4 mmol·L⁻¹ to 3.0 ± 1.2 mmol·L⁻¹. The mean EE for each karate exercise ranged from 322.7 ± 76.4 kJ to 636.7 ± 69.9 kJ. The mean EE for the entire 70-min practice and EPOC were 2355.4 ± 316.3 kJ and 38.8 ± 32.7 kJ, respectively (data not shown).

TABLE 1: Blood lactate, RPE, RER, and energy expenditure (EE) before, during, and following karate training.

Relationship between %HR_max and %V̇O_2max are shown in Figure 3. Higher HR responses were elicited during all types of karate exercises studied for given %V̇O_2max than during the treadmill run.

Figure 3: -Relationship between percent maximal HR and percent maximal oxygen uptake during karate exercises. S-B, basic techniques practiced in the stationary position; M-B, basic techniques practiced with body movements; T-1, sparring techniques performed without an opponent; T-2, sparring techniques performed against an opponent.

DISCUSSION

The American College of Sports Medicine (ACSM) ⁽¹⁾ recommended the following quantity and quality of training to develop and maintain cardiorespiratory fitness and body composition in healthy adults: frequency: 3 to 5 d·wk⁻¹; intensity: 60-90%HR_max, or 50-85% of V̇O_2max; duration: 20-60 min of continuous aerobic activity; and mode: any rhythmical and aerobic activity that uses large muscle groups and can be maintained continuously. Also, according to the ACSM ⁽¹⁾, the minimal training intensity threshold for improvement in V̇O_2max is approximately 60% of the HR_max (50% of V̇O_2max) which represents a HR of approximately 130-135 beats·min⁻¹ for young persons. The studies, which only reported HR responses without measuring V̇O₂, of selected combination techniques in TECH I and kata ^(17,18,21) suggested that these karate exercises can raise HR up to a level necessary for increasing cardiovascular fitness. However, these results need to be cautiously approached because in the present study higher HR responses were elicited during all types of karate exercises studied (S-Basics, M-Basics, TECH I, TECH II, and kata) for given %V̇O_2max than during the treadmill run. Similar results were reported during the kata performance ^(20,23). This could result from the static nature of the arm movements involved in these activities, the arm movements themselves, or the combined effects of this type of exercise performed by the arms ⁽²⁰⁾. Upper body exercises have been shown to induce a greater HR at a given V̇O₂ than lower body exercises ^(12,22).

Regarding training intensity of S-Basics, M-Basics, TECH I, and Tech II, there is no research that measured both V̇O₂ and HR responses of these karate exercises, so that we could not make any valid comparison. In the present study, the mean %V̇O_2max and %HR_max for S-Basics were below the accepted threshold and for M-Basics, TECH I, and TECH II were above the threshold for increasing V̇O_2max.

The V̇O₂ and HR responses of performing karate kata have been reported ^(20,23), but no consistent results have been obtained. Zehr and Sale ⁽²³⁾ investigated the V̇O₂ and HR of the kata performed for 8-10 min under two different conditions: performing each kata in approximately 1 min (PACE) and in 30 s (FAST). The mean %V̇O_2max for PACE and FAST kata were 73 ± 3% and 94 ± 2% of leg cycling V̇O_2max, respectively. The corresponding %HR_max were 93 ± 6% and 101 ± 3%, respectively. The authors concluded that karate kata can be used as an effective and specific means for training aerobic capacity in karate practitioners. Shaw and Deutsch ⁽²⁰⁾, on the other hand, investigated the V̇O₂ and HR responses of beginner's kata under four different conditions: kata performed 15 times without rest at 30- or 45-s pace or with a 1-min rest between each kata at 30- or 45-s pace. The authors reported that performing a kata at a 30-s pace without rest resulted in a V̇O₂ that was at least 50% of V̇O_2max, which is the accepted threshold for increasing V̇O_2max⁽¹⁾. No other combinations of kata pace or rest time produced a V̇O₂ that was at least 50% of V̇O_2max. In the present study, the mean %HR_max for performing kata was slightly above the accepted threshold, and the mean %V̇O_2max was slightly below the accepted threshold for increasing V̇O_2max.

The disparities in findings may reflect differences in the cardiorespiratory fitness levels, karate experience, and skill levels of the subjects and/or levels of kata studied (beginner or advanced). Zehr and Sale ⁽²³⁾ investigated the advanced kata in highly skilled karate practitioners with mean experience of 14.3 yr. Their subjects had approximately 10 mL·kg⁻¹·min⁻¹ lower V̇O_2max than the subjects in the present study. Shaw and Deutsch ⁽²⁰⁾ investigated the beginner's kata. Their subjects had the mean V̇O_2max in mL·kg⁻¹·min⁻¹ very similar to the subjects in the present study. However, their subjects had wide range of karate experience, from 4 months to 120 months. Thus, it is difficult to interpret how representative the results are for skilled or novice karate practitioners. In contrast to these reports, in the present study each subject performed each of five beginner's kata and two advanced kata first by the leader's count and second by each subject's own speed and then freely practiced favorite kata for few minutes, which is similar to kata practice during a regular workout.

Regarding the entire 70-min practice, the mean %HR_max (72.6 ± 9.2%) was slightly above the accepted threshold, and the mean %V̇O_2max (47.4 ± 5.9%) was slightly below the accepted threshold for increasing V̇O_2max. RPE ranged from 12.6 ± 0.8 to 14.3 ± 1.4, which corresponds to a perception of effort as moderate to somewhat hard ⁽⁴⁾.

ACSM ⁽¹⁾ suggested exercising at least 3 d·wk⁻¹ for at least 20 min and with sufficient intensity to expend approximately 1255.2 kJ (300 kcal) per exercise session as a threshold for total body mass and fat mass loss. During exercise, when V̇O₂ is submaximal and constant and when blood lactate concentration is constant, a steady rate of V̇O₂ exists, which can be used to represent the caloric cost of exercise. In hard-intensity exercise, lactate is produced and appears in the blood. However, because most (about 75%) lactate formed in some sites (e.g., in contracting fast-glycolytic fibers) as the result of anaerobic glycolysis is removed by oxidation at other sites (e.g., in heart and oxidative fibers), the V̇O₂ still provides a valid measure of the energy flux. In terms of net energy production, the anaerobic component from accumulated lactate is small (only a few percent) compared with that from oxidative metabolism ⁽⁶⁾. In the present study, the mean blood lactate responses to the five types of karate exercises were moderate, ranging from 1.4 ± 0.4 mmol·L⁻¹ to 3.0 ± 1.2 mmol·L⁻¹.

When calculating EE, the conversion factor for 1 L of oxygen when RER is one or 0.7 is 21.1 kJ or 19.7 kJ, respectively. The calculated EE resulting from the entire 70-min karate practice equals 2464.4 kJ when assuming RER is one and equals 2292.8 kJ when assuming RER is 0.7 ⁽⁶⁾. Because the mean values of RER obtained during the five types of exercises ranged from 0.81 ± 0.04 to 0.89 ± 0.07, the mean EE resulting from the entire 70-min karate practice was in between these values (2355.4 ± 316.3 kJ). Thus, even if the data in the present study should be regarded with some caution in view of the many approximations and assumptions involved in the indirect calorimetry ⁽⁶⁾, the mean value of EE resulting from the entire 70-min karate practice was well above the accepted threshold for total body mass and fat weight loss.

The results of the present study showed no evidence of a prolonged EPOC following karate training. These results are in agreement with previous studies that failed to show a prolonged EPOC following weight training, bicycle, and/or treadmill exercises ^{(5,9,15,16,19)} but conflict with others ^(2,3,14). These disparities in findings may reflect a myriad of mechanisms of which we have no data ⁽¹¹⁾. However, the present study controlled food intake 1 d before each experiment, and the subjects performed the experiment following a 10-h fast. Cigarette smoking, alcohol or beverages other than water, and physical exercise were not allowed 1 d before and during each experiment. The subjects slept in the laboratory with a temperature set at 22°C before the experiment and reported that they had had a normal night of sleep. The subjects were all first degree black belt with 2.5 ± 0.5 yr of karate experience and were familiar with all types of karate exercises studied in the present study.

In conclusion, the mean %V̇O_2max and %HR_max for S-Basics were below the accepted threshold, and for M-Basics, TECH I, and TECH II they were above the threshold for increasing V̇O_2max. For kata, the mean %HR_max was slightly above the threshold, and %V̇O_2max was slightly below the threshold for increasing V̇O_2max. The training intensity of karate exercises studied was moderate and effects of karate training on EPOC were minimal; however, the mean EE resulting from the entire 70-min karate training session was well above the accepted threshold for total body mass and fat weight loss.