Very little is known about the physical demands of boxing and the energy expended during a typical boxing training session. Rather, most research in boxing has been concerned with diagnosis and description of acute and chronic damage to the brain tissue as a result of blows to the head(1,6,8,10,12,13). As a result of the concern about the risk of head injuries associated with full contact boxing, there has been a move toward a form of training that retains many aspects of boxing training as far as exercise benefits and skill acquisition are concerned, but eliminates any body contact and blows to the head (11).
The noncontact boxing training session was developed by former boxers and personal trainers in the United States, as a high intensity exercise modality(4,11). The training session consists of either an hour of “shadow” boxing using various combinations of punches and skipping or a circuit-type program with participants spending a set time at each exercise station. At each of these exercise stations a variety of combinations of punches and defensive moves are performed repetitively.
However, while the number of participants in this type of exercise training has increased, little is known about the energy expenditure of the training and hence the specificity and effectiveness of the sport as a form of physical exercise. Although one previous study examined the effect of a 2-wk boxing training protocol on punch velocity, punch endurance, and 800-m running speed, no effort was made to quantify the energy expenditure during a routine training session (3). Therefore, the aim of this study was to quantify the energy expenditure of a 1-h noncontact boxing training session and to compare these results with the energy expenditure of a more conventional recreational activity such as running.
Subjects. Eight, healthy males accustomed to noncontact boxing training and performing at least one boxing training session per week, were recruited for the study. All subjects signed an informed consent after risks and procedures involved in the study were explained. The study was approved by the Ethics and Research Committee of the Faculty of Medicine of the University of Cape Town.
Study design. Before the trials all subjects reported to the laboratory for anthropometrical assessment of muscle mass(7) and body fat content (5). The subjects were randomly assigned to begin testing either with a 1-h boxing training session in the laboratory (BOXL) or the treadmill run in the laboratory (TREAD). A week later the subjects who started with BOXL underwent TREAD and vice versa. Between these sessions another boxing training session was performed at a boxing studio (BOXS). All boxing workouts were directed by the same professional boxing trainer.
Laboratory boxing training session (BOXL). The exercises used for this session were designed to be as similar as possible to the exercises used for structured boxing training in the studio. Subjects performed BOXL individually under the supervision of an instructor. The same instructor was used to regulate exercise intensity in the laboratory and studio exercise sessions. During this test the subject wore an air-tight mask (100 g) covering both his nose and mouth, and expired air was analyzed using an Oxycon system(Oxyconsigma, Mijhnardt, Bunnik, Netherlands). The tube connecting the mask to the analyzers was supported from above, minimizing its mass. Before each test, flow meters were calibrated with a 3-L syringe (Hans Rudolf 5530, Kansas City, MO), and the O2 and CO2 analyzers were calibrated with a gas mixture containing 4.5% CO2 with the remainder made up of an N2 mixture and room air. Oxygen consumption (˙VO2) and respiratory exchange ratio (RER) were measured continuously for the hour of the boxing training session. The ˙VO2 and RER data were used to predict energy expenditure during the 1-h workout (14). The measurement error using this procedure is less than 4% (9). Heart rate was recorded continuously during each test (Polar Vantage XL, Polar Electro, Kempele, Finland).
The boxing training session was performed using the following boxing equipment: 700-g focus pads, a 60-kg heavy bag, a 38-kg medium bag, and boxing gloves weighing 310 g, which the subjects wore after having their hands wrapped. The training session was divided into a 5-min warm-up, 50-min workout, and 5-min cooldown. The subject was given water to drink at 20, 40, and 50 min during the trial. The air-tight mask was removed for about 30 s during this period. Table 1 describes the total time of the training session and the total time on each exercise. The training session intensity was to a large degree determined by the boxing trainer as the workout was performed on a “one-on-one” basis.
Studio boxing training session (BOXS). This training session took place in a boxing studio and lasted 1 h. The subjects participated in a class of four to six individuals under the supervision of the same instructor who controlled BOXL. The format and time spent at each station was similar to that described in Table 1 except that the intensity of BOXS was determined by the subject to a greater degree than during BOXL which was conducted on a “one-on-one” format. Heart rate was measured continuously during the workout.
Treadmill session (TREAD). After warming up for 5 min the treadmill speed was set at 10 km·h-1. Every 5 min thereafter the speed of the treadmill was increased by 1 km·h-1 until the subject was unable to maintain the pace of the treadmill. During the treadmill test the subjects' ˙VO2, RER, and heart rate were measured continuously using the same equipment described above. This data was used to predict the subject's energy expenditure at each treadmill speed(14).
Statistics. Total area under the curve for ˙VO2, RER, and heart rate was analyzed using GraphPad Prism software (GraphPad Software, Inc., San Diego, CA). A paired t-test was used to compare heart rate results for BOXL and BOXS. A linear regression analysis was used to determine the relationship between running speed and energy expenditure in TREAD. Using this equation the running speed was determined at which the energy expenditure was similar to the energy expended during BOXL. Statistical significance was accepted when P < 0.05. All values are expressed as mean ± SD.
The subject characteristics are described in Table 2. Typical responses for a subject's heart rate, ˙VO2, and RER recorded during BOXL is shown in Figure 1 (subject 3). The variations in the responses can be compared with those from the training session described in Table 1. In this example the subject's energy expenditure was 3015 kJ·h-1. The energy expenditure of all the subjects during BOXL are shown inTable 3. The values ranged from 2519 to 3079 kJ for the training session. This value represents energy expenditure for the complete training session, including warm up and warm down periods. The average energy expenditure for the group was 2821 ± 190 kJ·h-1.
Seven of the eight subjects had higher heart rates during BOXL than during BOXS (Fig. 2). The average heart rate achieved for the group during BOXL was 7% higher than their average heart rate during BOXS (147± 12 vs 138 ± 19 beats·min-1; P < 0.05). The correlation coefficient between heart rates in BOXL and BOXS was r= 0.89, as shown in Figure 2.
The correlation coefficient between running speed and energy expenditure for the entire group during the TREAD protocol was r = 0.99. The predicted running speed at which each subject expended an amount of energy similar to that expended in BOXL is shown in Table 3. The average running speed of the group was 9.2 km·h-1 ± 0.8 km·h-1 (Table 3).
This study showed that the average energy expenditure during a typical boxing training session in the laboratory was 2821 ± 190 kJ·h-1. But the average heart rate was about 7% higher in BOXL compared with that in BOXS. Assuming this increase in heart rate was a true reflection of an increased energy expenditure, then the energy expenditure in this training session was about 7% higher than the energy expenditure during a similar training session in a boxing studio. It might be argued that the subjects' higher heart rate in BOXL was the result of an increased sympathetic arousal and therefore did not accurately reflect an increased energy expenditure. However, this is unlikely to have been the explanation in this study as all the subjects were familiarized with the testing procedures and were accustomed to the exercise protocol. It may also be argued that the increased mass of the equipment attached to the subjects during BOXL increased their workload. But the mask only weighed 100 g and the tubes connecting the mask to the analyzers were suspended, making this mass negligible. Therefore, it is unlikely that the mass of the equipment accounted for an increased workload and increased heart rate during BOXL. Rather, this difference in exercise intensity can be explained because during BOXL the subjects' intensity was regulated by the trainer, whereas during BOXS the subject was part of a class in which the exercises were similar but the subject was more able to regulate his own exercise intensity.
The next part of the study was to compare the energy expenditure during BOXL with that during a more conventional mode of exercise such as running on the treadmill. This part of the experiment showed that the energy expended during BOXL was equivalent to running at 9.2 ± 0.8 km·h-1 for 1 h on a horizontal treadmill. This predicted speed was derived by substituting energy expenditure into the linear regression equation of energy expenditure versus running speed. The predicted running speed (9.2 km·h-1) is slightly lower than the running speed (10 km·h-1) of the protocol used to establish the relationship between energy expenditure and running speed. But we believe it is acceptable to use the regression equation established for each individual because the relationship between energy expenditure and running speed is linear (r = 0.99) and extends to slower speeds. Davies (2) has shown that the energy cost of running on a treadmill is less than running at similar speeds on a running track. Therefore, this value of 9.2 km·h-1 is an overestimation of the speed for subjects running on a track.
Energy expenditure during BOXL was expected to be higher than the 2821± 190 kJ·h-1 measured in this study. This was based on the observation that during the training session the subjects appeared exhausted at certain stages. But the oxygen consumption and heart rate data were collected for the complete 60 min and included the warm-up, recovery, and warm-down exercises, all which consumed little energy compared to the high-intensity phases of the training session.
In conclusion, noncontact boxing training is becoming more popular as a form of exercise training and as a form of cross-training for a variety of sports. But little is known about the physical demands of this mode of exercise, and it is therefore difficult to prescribe this mode of exercise precisely. This study shows that a typical training session lasting 60 min causes a person to expend 2821 ± 190 kJ·h-1, the same amount of energy as someone running about 9 km in 60 min on the treadmill.
The authors wish to thank E. V. Lambert and J.H. Goedecke for assistance rendered during the completion of the study.
Address for correspondence: Dr. A. St. Clair Gibson, MRC/UCT Bioenergetics of Exercise Research Unit, Department of Physiology, University of Cape Town Medical School, Observatory, 7925 RSA, Cape Town, South Africa. E-mail:AGIBSON@SPORTS.UCT.AC.ZA
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Keywords:©1997The American College of Sports Medicine
ENERGY EXPENDITURE; BOXING; INDIRECT CALORIMETRY; HEART RATE; RUNNING