Europ. J. appi. Physiol. 36, 1-6 (1976) European Journal of

Applied Physiology and Occupational Physiology �9 by Springer-Verlag 1976

Urinary Epinephrine and Norepinephrine Levels in Women Athletes during Training and Competition

D. Pierce 1., I. Kupprat 1.*, and D. Harry 2

Human Environmental Research Unit, Department of Physiology and Biophysics, University of Illinois, Urbana, Illinois, USA

Department of Health and Physical Education for Women, Miami University, Oxford, Ohio, USA

Abstract, Training and competitive epinephrine and norepinephrine levels and proportions were compared in two groups of women athletes to determine whether changes in catecholamine excretion reflect the added mental stress of athletic competition on physical effort. An intercollegiate basketball team and a group of track and field athletes volunteered as subjects. Competitive epineph- rine urinary levels were significantly (P < 0.01) higher than training levels. A concomitant rise in the norepinephrine with an increase in physical effort was observed in both groups of athletes following training sessions as well as after athletic competition. Track and field athletes trying to qualify for an internation- al team exhibited significantly (P < 0.01) higher epinephrine levels than the team members; thus suggesting that anticipation of competiton imposes a mental stress on an athlete. Constant changes in the catecholamine pattern as against a normal work load have yet to be established.

Key words: Catecholamines - Epinephrine -- Norepinephrine - Training -- Competition.

Introduction

Exercise subjects the body to physical stress; competition introduces emotional fac- tors. Adaptation to emotional stress is physical in nature and in many ways similar to that produced by stressors of a physical nature. The catecholamines exert a profound influence on the cardiovascular system and metabolism, thus enabling the body to function in a stress situation. Some of the stress responses occur prior to any actual physical involvement. Anticipatory heart rates have been shown in ski jumpers (Imhof et al., 1969) and runners (Howard et al., 1966). Catecholamine

* Present address and address for offprint requests: Westfield State College, Westfield, Massachu- setts, USA ** Present address: Institute of Environmental Stress, University of California at Santa Barbara, Santa Barbara, California, USA

2 D. Pierce et al.

changes have been reported shortly before speed skating (Ehringer and Spreitzer, 1967), ice hockey (Elmadjian et al., 1958) and exercise routines (Juchmes et al., 1971). Since adrenal medul lary involvement in emotional stress was demonstra ted by Cannon and de la Paz (1911), much work has been done to elucidate the part played by epinephrine and norepinephrine in maintaining proper circulation, metab- olism and mental alertness. There is agreement among investigators that urine cate- cholamine levels, though representing only a small port ion of the total catechol- amines released into the blood stream, are a good reflection of sympathoadrenal activity. Under normal conditions epinephrine and norepinephrine are continuously produced and released in the body. Since chromaffin cells are the sole source of epinephrine, and most chromaffin cells are in the adrenal medulla, the ur inary excre- tion of epinephrine may be associated rather specifically with adrenal medulla activ- ity. Likewise, norepinephrine values correlate with adrenergic nerve activity as some norepinephrine enters the circulatory system from the nerve endings, and little nor- epinephrine is of adrenal origin.

At tempts to correlate different types of stress reactions with differential excre- tion of epinephrine and norepinephrine have yielded varying results. Catecholamine changes m a y be found not only in persons physical ly participating, but also in individuals subjected to the mental stress of competition. Nowack i et al. (1969) found the catecholamine levels in the coxswain were higher before a race than in any of the other crew members. Epinephrine increases are generally related to emotional arousal, whereas reflexly induced norepinephrine changes are in response to active aggressive changes (Becker and Kreuzer, 1969; Bryson, 1971; Elmadj ian et al., 1958; Euler and Hellner, 1952; Goodal l and Berman, 1960; Kfirki, 1956; Lutwak et al., 1969).

The present study was designed to determine whether the epinephrine port ion of the catecholamines might indicate the added stress of athletic competi t ion of physi- cal effort.

Materials and Methods

Two groups of women athletes volunteered as subjects; ranging in age from 17-26 years, in height from 155--180 cm, and in weight from 47--82 kg. The basketball players were members of intercolle- giate varsity and junior varsity teams from Miami University, Oxford, Ohio. They had practiced for 2 h-5 days a week for 4 weeks prior to testing. The track and field athletes had been selected to compete in a show meet and an international meet. This group of athletes had assembled at the University of Illinois, Urbana, Illinois, from various sectors of the country and individual training methods were continued.

Since urine epinephrine and norepinephrine levels reflect blood catecholamine levels and there is little inconvenience in collecting samples, as well as no interference with physiologic functions during collection, urine was used for the analyses. Samples were collected and stored in ice until adjusted to pH 3.5 _+ 0.2 with HC1 and stored at -5 ~ C until analyzed in random order in duplicate. Epinephrine and norepinephrine were determined on 5 ml aliquots following the method of Griffiths et al. (1970), with readings taken on the fluorescent trihydroxyindole derivatives in an Aminco-Bowman spectropho- tofluorometer at appropriate times and wavelengths. The catecholamine values were corrected for recovery (73.1% for epinephrine; 65.6% for norepinephrine). Since timed urine specimens were not obtained, the percentages of the individual catecholamines were determined in addition to the absolute epinephrine and norepinephrine values.

Urine samples, collected from women athletes during physical examinations were used as control values.

Epinephrine and Norepinephrine Levels: Training versus Competition 3

Comparisons between training and competitive epinephrine and norepinephrine levels were made separately for the intercollegiate basketball team participants and the track and field athletes. For each group of athletes significant differences were determined using a 2-factor analysis of variance with repeated measures across trials (pre and post). Mean catecholamine levels pre and post basketball practice and game were also compared using a paired t test (Huntsberger and Billingsley, 1973).

Results

Since the level, intensity, durat ion of training, and caliber of competi t ion differed between the t rack and field athletes and the intercollegiate basketbal l part icipants, they were considered two distinctly different populat ions despite the similarity of testing conditions. Therefore, each populat ion was treated separately for statistical comparisons between training and competit ive levels.

Intercollegiate Basketball Team Players

Mean levels 0xg/ml) of epinephrine and norepinephrine excreted both before and after a pract ice session and an intercollegiate basketbal l game are presented in Table 1. No statistically significant differences (paired t test) were found in pre- practice and pre-game epinephrine and norepinephrine levels between those who started the game and those who sat on the bench. Therefore, the epinephrine and

Table 1. Epinephrine and norepinephrine excretion in 2 groups of athletes during training and competition

Norepinephrine Epinephrine (~g/ml) (~g/ml)

Basketball players (N = 18)

Pre-practice 0.026 • 0.003 0.023 • 0.002 Post-practice 0.060 • 0.005 0.032 • 0.004 Pre-game 0.025 • 0.002 0.029 • 0.004 Post-game 0.070 • 0.005 0.044 • 0.006

Track and field athletes

No. 1 Post-training 0.037 0.021 Pre-international meet 0.043 0.041

No. 2 Pre-training 0.023 0.013 Post-tralning 0.046 0.060 Pre-show meet 0.023 0.010 Post-show meet 0.045 0.067 Pre-international meet 0.035 0.035

No. 3 Pre-training 0.023 0.013 Post-training 0.029 0.022 2 days pre-international meet 0.021 0.021 1 day pre-international meet 0.028 0.047

4 D. Pierce et al.

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Epinephrine excretion in basketball players during practice and game situations Epinephrine excretion in track and field team members and team aspirants

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Fig. 2

norepinephrine levels shown represent those observed for the entire team (N = 18). The univariate analysis of variance indicated that the percent epinephrine during the game situation was significantly (P < 0.01) higher than during practice (Fig. 1). Post-practice and post-game norepinephrine levels were significantly (P < 0.01) higher than the pre-practice and pre-game levels (Fig. 1).

Track and Field Athletes

Epinephrine and norepinephrine levels of three athletes during training and competi- tion are presented in Table 1. Although epinephrine levels during training were similar, the increment in percent epinephrine excretion during international competi- tion differed considerably among the three individuals (Table 1). Analysis of vari- ance revealed the mean epinephrine levels during competition increased significantly (P < 0.01) over training levels.

Comparisons of epinephrine levels during training among individuals (N = 11) who were trying to qualify for the international team during the training camp and those who had already qualified were made (Fig. 2). For the individuals trying to qualify for the team, the epinephrine levels were significantly (P < 0.01) higher than those of the team members. Those who made the team during the training period had significantly higher epinephrine values than those who failed to qualify.

Discuss ion and Conc lus ions

Despite differences in the level and duration of training, and the caliber of competi- tion between the intercollegiate basketball team players and the track and field ath- letes, similar catecholamine changes were observed in both groups of athletes. An

Epinephrine and Norepinephrine Levels: Training versus Competition 5

increase in the percent epinephrine (of the epinephrine plus norepinephrine) can mean that epinephrine increases relatively more than the norepinephrine, the epi- nephrine increases while the norepinephrine remained relatively constant, the norepi- nephrine decreases while the epinephrine remains the same, or the epinephrine in- creases as the norepinephrine decreases.

The higher pre-game catecholamines, as compared to the pre-practice levels, was due to an increased epinephrine excretion among the basketball players. The greater amount of catecholamines excreted after a game as compared to before a game or after practice is due to an increase in both the epinephrine and norepinephrine. It is normal for an athlete to exert more physically in a competitive situation than during a routine practice. Thus, the higher norepinephrine excretion observed in the post- game situation is to be expected. Although the percent epinephrine pattern is similar before and after the practice and game period, it can be noted that, whereas the norepinephrine excretion was 32.2% higher after the game than after practice, (0.070 ~g/ml versus 0.060 ~g/ml), there was an 88.8% epinephrine increment (0.044 ~g/ml versus 0.032 ~g/ml), which could be interpreted as a reflection of the emotion- al stress of the game.

Among the track and field athletes, the percent epinephrine and norepinephrine during training were similar despite large differences in the excretion concentrations. However, the increment in percent epinephrine excreted during competition (as com- pared to training) differed considerably among the three individuals. One individual (subject No. 2, Table 1) who had previously qualified for the international team, participated in a show meet just prior to departure for international competition. The similar catecholamine patterns before and after a training session and the show meet could be indicative of the absence of serious competition in her speciality, or due to the mental security of being a member of the team.

The smaller pre to post increase in norepinephrine excretion levels of the track and field athletes during the training session as compared to the basketball players before to after a practice session might be attributed to less physical exertion, or indicate a greater physiological efficiency in the more highly trained individuals. Large catecholamine differences have been reported in fit individuals under normal conditions and while engaged in similar tasks (Lutwak et al., 1969).

The observed higher epinephrine levels prior to, and during competition, suggest that anticipation of a competitive event results in emotional arousal. However, no constant changes in the proportion of epinephrine and norepinephrine excreted when compared against a normal work load, as measured by O z consumption, heart rate, or blood pressure has been shown (Euler and Hellner, 1952; Howard et al., 1966; Imhof et al., 1969). Therefore, the degree of additional stress (as reflected in changes in the epinephrine excretion) that a specific task imposes during competition is not consistent within a group.

Mental and physical stresses of athletic competition are translated biochemically in terms of increases in epinephrine and norepinephrine excretion. However, the wide range of individual epinephrine excretion increments in the track and field athletes between training and competition, and among the basketball players between prac- tice and a game situation, have not demonstrated that the additional stress which emotional arousal imposes on the physical effort during athletic competition can be quantified.

6 D. Pierce et al.

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Received March 16, 1976