The effects of
conditioning on cardiorespiratory function in adolescent boys GREGORY B. SHASBY, MS AND FEDERICK C. HAGERMAN. Ph.D.
Pulse rate and oxygen consumption were measured for 19 boys (aged 12-13) assigned to either Distance, Interval, or No-Training regimens, during a 5 min. run at 6 m.p.h., zero % grade on a motor driven treadmill prior to a 12 week conditioning period, following conditioning, and after four months of deconditioning. Oxygen consumption was assessed by opencircuitry and heart rate monitored by direct electrocardiography. Both condi-
tioning
groups
significantly improved
car-
diovascular fitness (Distance group. 175-152 beats/min. and Interval group: 175-159 beats/min.) at P < .01, but no differences were noted between them. They differed significantly from the Control group (P < .05) which showed no change (172-173 beats/min.). No significant differences occurred between 2 variables, but any of the groups for Vo Within group analysis statistically favored the Distance group. Post-conditioning and -deconditioning compari-
Gregory ucation,
B.
Shasby, Department of Physical EdUniversity of Connecticut, Storrs,
Conn. Dr. Frederick C. Hagerman is Associate ProfesDepartment of Zoology and Microbiology, The Ohio University, Athens, Ohio.
indicated that deconditioning had deleterious effect on cardiorespiratory function. Cardiorespiratory fitness improved to the extent that competitive running events of 2-6 miles are suggested for this age group, but as the data indicated, only after sufficient training. Task similarity of training and standard test and running volume apparently afforded a slightly greater improvement of cardiorespiratory fitness in the Distance group. Marked deterioration of fitness during deconditioning was attributed to complete absence of a training stimulus. sons a
INTRODUCTION
Organized
sports for the pre-pubescent youngster have increased to incredible pro-
portions during the last 15 years. Age group swimming has had a significant effect on raising the competitive level of swimming in the U.S. to the highest in the world and a large proportion of our recent National and Olympic teams has been teen-agers. The current national interest in long-distance running has also affected the younger age groups and this is evident from the growing number of young people currently running
sor,
cross-country, distance track events, road
From the Exercise
performances
Physiology Laboratory,
De-
partment of Zoology and Microbiology, The Ohio
University, Athens, Ohio 45701.
and marathons and the many fine achieved by them in these activities. There has been a great deal of controversy races,
97
concerning the physiological and psychological benefits resulting from the participation of intermediate or junior high school age boys in formal endurance-type activities. Those who have opposed organized sports involving training have based their arguments on the apparent lack of physical readiness at this age, i.e., insufficient development of the respiratory and/or cardiovas11
or the idea that early systems9 lack the necessary emotional teen-age boys stability to endure the psychological stresses often encountered during training and competition.l2 However, there is also evi-
cular
dence supporting the participation of youngsters in endurance activities. Astrand, et a1.22 and Cureton4 both observed young competitive swimmers and found that they possessed very high aerobic capacities, displayed normal cardiovascular development, and showed outstanding endurance. Several earlier studies have defended the participation of healthy young boys in endurance activities without fear of injury to the normal heart.&dquo;, 11 11 More recent data have shown that maximal physical working capacity, based on body weight measured for boys, ages 7-13 years, compared favorably with figures obtained for adult men.~ Physiological responses of normal healthy boys, ages 10-17, were observed during a moderate steady state exertion and it was found that boys, ages 12-14 years, showed an elevated heart rate but deceleration after exercise was more rapid for this age group than for either younger or older subjects. 15 There is a scarcity of data regarding the effects of conditioning on respiratory and cardiovascular fitness of teen-age boys. Information regarding the acute or chronic effects of specific contemporary training methods on this age group is practically non-existent and there have been no follow-up studies to determine influences of deconditioning. Running performance and maximal and submaximal Vo2, ml./min. of 10-15 year old boys improved over a 22 month period of distance-running training. Since weight gain was noted in all subjects, significant changes were not found in Vo2 measurements, ml. /kg. /min.5Certain static respiratory function tests and cardiovascular parameters among boys, 9-10 years, signifi98
cantly improved as a result of organized training. 13 Significant increases were noted in maximal Vo2 and peak pulse rate for conditioned girls and boys, ages 10 14, over a 12 month period as opposed to no change in these variables in youngsters not exposed to organized conditioning. Ekbloms investigated the effects of physical training and no training for a 32 month period on adolescent boys, age, 11years, by observing changes in certain anthropometric and cardio-respiratory function measures. Trained subjects showed greater increases in vital capacity and maximal Vo2 and a decrease in endexercise heart rate after the conditioning
period. PROCEDURES
Twenty-one untrained male subjects, ages 12-13 years, were randomly selected from physical education classes at the Athens, Ohio Middle School. Age, height, and weight were recorded for each subject prior to training, following training, and again after the deconditioning period. Individual and mean values for these parameters are shown in Table 1. Written parental permission, including a signed liability release statement, and a thorough medical examination were required of each subject. Before actual testing began, each subject was familiarized with the testing apparatus and experimental procedure on at least 3 different occasions. When the heart rate and respiratory function data began to show a high degree of consistency then it was assumed that the subject had become acquainted with the laboratory conditions and that any learning effect had been eliminated. The subjects were assigned to one of three groups; distance training, interval training, or no training (control) based on heart rate and Vo2 responses while performing a submaximal run on a motor driven treadmill. The groups were equated by using paired mean selection and verified equated by applying a t test to the group means. The results of the t test showed no significant differences among group means for heart rate or
Each
Vo2.
tested on 6 different the training program for the purpose of establishing a basic condi-
subject
was
occasions; prior to
TABLE 1
Age, Height, and Weight of Subjects
tioning level and for placement into study the end of every three weeks for a 12 week period of experimental study, and finally, after four months from the termination of formal experimentation. The testing procedure for the pre-conditioning and postdeconditioning tests dictated a 5 minute run groups, at
at 6
m.p.h.
at zero %
grade
on a
motor
driven treadmill (W. E. Collies, Inc., model P-3800). Heart rate was measured throughout the experiment by direct electrocardiography using a Hewlett-Packard, model 1500A ECG. Exercise metabolism was determined by the Douglas bag open-circuit method with gas collection carried out during the final minute of exercise. One hun-
dred-twenty liter neoprene latex collection bags, tubing and valves of 3.5 cm. internal diameter, and an Otis-McKerrow valve
modified with a central divider to reduce dead spacel4 were used for gas collection and expired ventilation volumes were measured spirometrically. Mixed expired CO2 concentrations were measured with a Beckman, model 215R, infrared analyzer. Calibration curves were constructed with four gases of known concentration before and after every analysis of an expired sample. Expired O2 concentration was measured with a Beckman, model E-2, paramagnetic meter. Oxygen uptake and CO2 output were calculated from expired gas concentrations in the usual manner. The testing technique was used in its entirety for the pre-conditioning, post-conditioning and post-deconditioning tests but only pulse rate was measured during the tests which were conducted every three weeks during the conditioning period. 99
Three matched groups of equal size (n were selected by using paired mean observations of Vo2 data, both in liters/mm. and ml./kg./min., obtained from the pretraining test. Two subjects assigned to the interval group had to drop from the study shortly after conditioning began due to personal reasons not related to the conditioning process. After an adequate warm-up time of stretching exercises and jogging, those subjects assigned to the interval group participated in a training program consisting of repeated runs of 50-200 yards with the time of each rest period determined by cardiac recovery. The boys trained three times per week under the careful supervision of a physical education undergraduate student. Since the subjects had no prior experience in a formal conditioning program, it =
7)
TABLE 2
i.e ; 10 100
x
Interval
50
Training Program
(10 repetitions
at
50
yards)
decided to begin work at a very low level. Initially it was difficult for the boys to establish a suitable running pace for repeated efforts, however as training progressed into the third week they seemed to adapt to this regimen. The interval training program is summarized in Table 2. The subjects were asked to run each interval near maximum effort but yet within their physical limits so that additional runs could be accomplished. Running times were not measured. The time of each rest period was determined by palpation of pulse rate at the carotid artery for 15seconds, then multiplied by 4 to calculate beats/min. When the rate had dropped to 120-135 beats/min., another effort was begun. At the beginning of training the 120 recovery level was used but as the subjects’ conditioning improved it was
TABLE 3
was
Distance
necessary, if
a
Training Program
training stimulus
was
to
realized, to revise this level progressively upward. The times of recovery ranged from be
45-90 sec. depending on the severity of the workout and the conditioning levels of the subjects. Heart rates taken immediately after running ranged from 160 175 beats/ min. This procedure and the results approximate those described by Gerschler and Reindell (18), however recovery heart rate levels had to be revised downward to accommodate this age group. The distance group, led by a physical education graduate student, who was an
experienced long-distance
runner, also
exer-
cised three times per week. They began training by jogging easily and continuously over the university golf course and then moved to road running after familiarization with prolonged steady state exertion. This group logged a total of 6 miles during the first week; running one mile, resting, and then running another mile during each training session. They ran a total of 17 miles during the 12th week of training with their
run being 7 miles. This program, like the interval training regimen, was designed to provide progressive resistance to the cardiorespiratory system. Each boy ran at his own pace and exercise severity was altered by changing the pace of the distance run. The distance training program is outlined in Table 3. The members of the control group participated in no organized form of training other than those activities presented to them in school physical education classes. Deconditioning as defined in this study was the period of time when no formal training regimen was pursued by any of the treated groups. All subjects abstained from any form of organized physical conditioning, other than some limited school activities, for a period of four months after the
longest
conditioning
process.
RESULTS
Pulse rates and
Vo2 measurements for the
pre-conditioning and post-conditioning tests and post-deconditioning test are summa101
TABLE 4
Comparison
rized in Table 4. The were
of
Cardiorespiratory
objectives
of the
study
to compare the effects of two different
types of running training programs and
no
performance; to determine when significant effects, if any, began to appear; and to observe any changes in test data after a prolonged period of deconditioning. A lowered pulse rate and a decrease training
on
human
Vo2 parameters for the standard exercise indicated an improvement in conditioning. This is based on the fact that as cardiorespiratory function and running efficiency improve, energy cost for a standard workload diminishes. in
Pre- and
post-conditiomng
companson
analysis of variance. ABSET6 (IBM, 360-44), statistical design was applied to the pulse rate data to determme if significant An
102
Data
differences occurred between the groups and within the groups over time. Average pulse rates for each test are displayed in Figure l. As a result of obtaining significant F’s for B factors, these data were subjected to the Duncan Multiple Range Test (DMLRT) to determme which groups differed and at what point during the conditioning process differences were noted. Summaries of these analyses are shown in Tables 5 and 6. Pulse rate data from Table 4 indicate that both conditioned groups definitely improved cardiovascular fitness (distance group: 175-153 beats/min. and interval group: 179-159 beats/min.) and Table 5 shows that they differed significantly from the controls (172 173 beats/min.) at P < .01. Since a significant F was also calculated for the within treatment effect in ABSET6
Figure TABLE 5
I-Mean end-exercise
rates
for each
test session.
Analysis of Variance (ABSET6): Heart Rate (beats/min), V02 (1/min), V02 (ml/kg/min)>
for both conditioned groups (see Table 5), it was important to find during which week the significant improvement first occurred. This would indicate the pe-
analysis
pulse
nod of greatest cardiovascular function adaptation and thus reflect the first marked effect of the training stimulus. The summary of ordered means m Table 6 shows that test 103
TABLE 6
Duncan Multiple Range Test for Ordered Means: Between and Within Group Data
the pre- and post-conditioning scores in order to clarify individual treatment effects and these data are shown in Table 7. The distance group was the only group to significantly improve in all test variables; Vo2,
I/min: (P < .05), Vo2, ml./kg./min.: (P< .05), and pulse rate: (P < .01). The interval group showed
pulse
rate
(P
a
conditioning on cardiorespiratory function in adolescent boys GREGORY B. SHASBY, MS AND FEDERICK C. HAGERMAN. Ph.D.
Pulse rate and oxygen consumption were measured for 19 boys (aged 12-13) assigned to either Distance, Interval, or No-Training regimens, during a 5 min. run at 6 m.p.h., zero % grade on a motor driven treadmill prior to a 12 week conditioning period, following conditioning, and after four months of deconditioning. Oxygen consumption was assessed by opencircuitry and heart rate monitored by direct electrocardiography. Both condi-
tioning
groups
significantly improved
car-
diovascular fitness (Distance group. 175-152 beats/min. and Interval group: 175-159 beats/min.) at P < .01, but no differences were noted between them. They differed significantly from the Control group (P < .05) which showed no change (172-173 beats/min.). No significant differences occurred between 2 variables, but any of the groups for Vo Within group analysis statistically favored the Distance group. Post-conditioning and -deconditioning compari-
Gregory ucation,
B.
Shasby, Department of Physical EdUniversity of Connecticut, Storrs,
Conn. Dr. Frederick C. Hagerman is Associate ProfesDepartment of Zoology and Microbiology, The Ohio University, Athens, Ohio.
indicated that deconditioning had deleterious effect on cardiorespiratory function. Cardiorespiratory fitness improved to the extent that competitive running events of 2-6 miles are suggested for this age group, but as the data indicated, only after sufficient training. Task similarity of training and standard test and running volume apparently afforded a slightly greater improvement of cardiorespiratory fitness in the Distance group. Marked deterioration of fitness during deconditioning was attributed to complete absence of a training stimulus. sons a
INTRODUCTION
Organized
sports for the pre-pubescent youngster have increased to incredible pro-
portions during the last 15 years. Age group swimming has had a significant effect on raising the competitive level of swimming in the U.S. to the highest in the world and a large proportion of our recent National and Olympic teams has been teen-agers. The current national interest in long-distance running has also affected the younger age groups and this is evident from the growing number of young people currently running
sor,
cross-country, distance track events, road
From the Exercise
performances
Physiology Laboratory,
De-
partment of Zoology and Microbiology, The Ohio
University, Athens, Ohio 45701.
and marathons and the many fine achieved by them in these activities. There has been a great deal of controversy races,
97
concerning the physiological and psychological benefits resulting from the participation of intermediate or junior high school age boys in formal endurance-type activities. Those who have opposed organized sports involving training have based their arguments on the apparent lack of physical readiness at this age, i.e., insufficient development of the respiratory and/or cardiovas11
or the idea that early systems9 lack the necessary emotional teen-age boys stability to endure the psychological stresses often encountered during training and competition.l2 However, there is also evi-
cular
dence supporting the participation of youngsters in endurance activities. Astrand, et a1.22 and Cureton4 both observed young competitive swimmers and found that they possessed very high aerobic capacities, displayed normal cardiovascular development, and showed outstanding endurance. Several earlier studies have defended the participation of healthy young boys in endurance activities without fear of injury to the normal heart.&dquo;, 11 11 More recent data have shown that maximal physical working capacity, based on body weight measured for boys, ages 7-13 years, compared favorably with figures obtained for adult men.~ Physiological responses of normal healthy boys, ages 10-17, were observed during a moderate steady state exertion and it was found that boys, ages 12-14 years, showed an elevated heart rate but deceleration after exercise was more rapid for this age group than for either younger or older subjects. 15 There is a scarcity of data regarding the effects of conditioning on respiratory and cardiovascular fitness of teen-age boys. Information regarding the acute or chronic effects of specific contemporary training methods on this age group is practically non-existent and there have been no follow-up studies to determine influences of deconditioning. Running performance and maximal and submaximal Vo2, ml./min. of 10-15 year old boys improved over a 22 month period of distance-running training. Since weight gain was noted in all subjects, significant changes were not found in Vo2 measurements, ml. /kg. /min.5Certain static respiratory function tests and cardiovascular parameters among boys, 9-10 years, signifi98
cantly improved as a result of organized training. 13 Significant increases were noted in maximal Vo2 and peak pulse rate for conditioned girls and boys, ages 10 14, over a 12 month period as opposed to no change in these variables in youngsters not exposed to organized conditioning. Ekbloms investigated the effects of physical training and no training for a 32 month period on adolescent boys, age, 11years, by observing changes in certain anthropometric and cardio-respiratory function measures. Trained subjects showed greater increases in vital capacity and maximal Vo2 and a decrease in endexercise heart rate after the conditioning
period. PROCEDURES
Twenty-one untrained male subjects, ages 12-13 years, were randomly selected from physical education classes at the Athens, Ohio Middle School. Age, height, and weight were recorded for each subject prior to training, following training, and again after the deconditioning period. Individual and mean values for these parameters are shown in Table 1. Written parental permission, including a signed liability release statement, and a thorough medical examination were required of each subject. Before actual testing began, each subject was familiarized with the testing apparatus and experimental procedure on at least 3 different occasions. When the heart rate and respiratory function data began to show a high degree of consistency then it was assumed that the subject had become acquainted with the laboratory conditions and that any learning effect had been eliminated. The subjects were assigned to one of three groups; distance training, interval training, or no training (control) based on heart rate and Vo2 responses while performing a submaximal run on a motor driven treadmill. The groups were equated by using paired mean selection and verified equated by applying a t test to the group means. The results of the t test showed no significant differences among group means for heart rate or
Each
Vo2.
tested on 6 different the training program for the purpose of establishing a basic condi-
subject
was
occasions; prior to
TABLE 1
Age, Height, and Weight of Subjects
tioning level and for placement into study the end of every three weeks for a 12 week period of experimental study, and finally, after four months from the termination of formal experimentation. The testing procedure for the pre-conditioning and postdeconditioning tests dictated a 5 minute run groups, at
at 6
m.p.h.
at zero %
grade
on a
motor
driven treadmill (W. E. Collies, Inc., model P-3800). Heart rate was measured throughout the experiment by direct electrocardiography using a Hewlett-Packard, model 1500A ECG. Exercise metabolism was determined by the Douglas bag open-circuit method with gas collection carried out during the final minute of exercise. One hun-
dred-twenty liter neoprene latex collection bags, tubing and valves of 3.5 cm. internal diameter, and an Otis-McKerrow valve
modified with a central divider to reduce dead spacel4 were used for gas collection and expired ventilation volumes were measured spirometrically. Mixed expired CO2 concentrations were measured with a Beckman, model 215R, infrared analyzer. Calibration curves were constructed with four gases of known concentration before and after every analysis of an expired sample. Expired O2 concentration was measured with a Beckman, model E-2, paramagnetic meter. Oxygen uptake and CO2 output were calculated from expired gas concentrations in the usual manner. The testing technique was used in its entirety for the pre-conditioning, post-conditioning and post-deconditioning tests but only pulse rate was measured during the tests which were conducted every three weeks during the conditioning period. 99
Three matched groups of equal size (n were selected by using paired mean observations of Vo2 data, both in liters/mm. and ml./kg./min., obtained from the pretraining test. Two subjects assigned to the interval group had to drop from the study shortly after conditioning began due to personal reasons not related to the conditioning process. After an adequate warm-up time of stretching exercises and jogging, those subjects assigned to the interval group participated in a training program consisting of repeated runs of 50-200 yards with the time of each rest period determined by cardiac recovery. The boys trained three times per week under the careful supervision of a physical education undergraduate student. Since the subjects had no prior experience in a formal conditioning program, it =
7)
TABLE 2
i.e ; 10 100
x
Interval
50
Training Program
(10 repetitions
at
50
yards)
decided to begin work at a very low level. Initially it was difficult for the boys to establish a suitable running pace for repeated efforts, however as training progressed into the third week they seemed to adapt to this regimen. The interval training program is summarized in Table 2. The subjects were asked to run each interval near maximum effort but yet within their physical limits so that additional runs could be accomplished. Running times were not measured. The time of each rest period was determined by palpation of pulse rate at the carotid artery for 15seconds, then multiplied by 4 to calculate beats/min. When the rate had dropped to 120-135 beats/min., another effort was begun. At the beginning of training the 120 recovery level was used but as the subjects’ conditioning improved it was
TABLE 3
was
Distance
necessary, if
a
Training Program
training stimulus
was
to
realized, to revise this level progressively upward. The times of recovery ranged from be
45-90 sec. depending on the severity of the workout and the conditioning levels of the subjects. Heart rates taken immediately after running ranged from 160 175 beats/ min. This procedure and the results approximate those described by Gerschler and Reindell (18), however recovery heart rate levels had to be revised downward to accommodate this age group. The distance group, led by a physical education graduate student, who was an
experienced long-distance
runner, also
exer-
cised three times per week. They began training by jogging easily and continuously over the university golf course and then moved to road running after familiarization with prolonged steady state exertion. This group logged a total of 6 miles during the first week; running one mile, resting, and then running another mile during each training session. They ran a total of 17 miles during the 12th week of training with their
run being 7 miles. This program, like the interval training regimen, was designed to provide progressive resistance to the cardiorespiratory system. Each boy ran at his own pace and exercise severity was altered by changing the pace of the distance run. The distance training program is outlined in Table 3. The members of the control group participated in no organized form of training other than those activities presented to them in school physical education classes. Deconditioning as defined in this study was the period of time when no formal training regimen was pursued by any of the treated groups. All subjects abstained from any form of organized physical conditioning, other than some limited school activities, for a period of four months after the
longest
conditioning
process.
RESULTS
Pulse rates and
Vo2 measurements for the
pre-conditioning and post-conditioning tests and post-deconditioning test are summa101
TABLE 4
Comparison
rized in Table 4. The were
of
Cardiorespiratory
objectives
of the
study
to compare the effects of two different
types of running training programs and
no
performance; to determine when significant effects, if any, began to appear; and to observe any changes in test data after a prolonged period of deconditioning. A lowered pulse rate and a decrease training
on
human
Vo2 parameters for the standard exercise indicated an improvement in conditioning. This is based on the fact that as cardiorespiratory function and running efficiency improve, energy cost for a standard workload diminishes. in
Pre- and
post-conditiomng
companson
analysis of variance. ABSET6 (IBM, 360-44), statistical design was applied to the pulse rate data to determme if significant An
102
Data
differences occurred between the groups and within the groups over time. Average pulse rates for each test are displayed in Figure l. As a result of obtaining significant F’s for B factors, these data were subjected to the Duncan Multiple Range Test (DMLRT) to determme which groups differed and at what point during the conditioning process differences were noted. Summaries of these analyses are shown in Tables 5 and 6. Pulse rate data from Table 4 indicate that both conditioned groups definitely improved cardiovascular fitness (distance group: 175-153 beats/min. and interval group: 179-159 beats/min.) and Table 5 shows that they differed significantly from the controls (172 173 beats/min.) at P < .01. Since a significant F was also calculated for the within treatment effect in ABSET6
Figure TABLE 5
I-Mean end-exercise
rates
for each
test session.
Analysis of Variance (ABSET6): Heart Rate (beats/min), V02 (1/min), V02 (ml/kg/min)>
for both conditioned groups (see Table 5), it was important to find during which week the significant improvement first occurred. This would indicate the pe-
analysis
pulse
nod of greatest cardiovascular function adaptation and thus reflect the first marked effect of the training stimulus. The summary of ordered means m Table 6 shows that test 103
TABLE 6
Duncan Multiple Range Test for Ordered Means: Between and Within Group Data
the pre- and post-conditioning scores in order to clarify individual treatment effects and these data are shown in Table 7. The distance group was the only group to significantly improve in all test variables; Vo2,
I/min: (P < .05), Vo2, ml./kg./min.: (P< .05), and pulse rate: (P < .01). The interval group showed
pulse
rate
(P
a
