Air travel across four time zones in college swimmers.

Air travel across four time zones in college swimmers PATRICK J. O’CONNOR, JOHN S. RAGLIN, JOEL

WILLIAM P. MORGAN, G. TURNER, AND NED

KELLI F. KOLTYN, H. KALIN

Exercise and Sport Research Institute, Arizona State University, Tempe, Arizona 85287-0404; Sport Psychology Laboratory, University of Wisconsin-Madison, and W. S. Middleton Memorial Veterans Administration and Department of Psychiatry, University of Wisconsin Medical School, Madison, Wisconsin 53706; and Department of Kinesiology, Indiana University, Bloomington, Indiana 47405 O'CONNOR,PATRICK J., WILLIAM P. MORGAN, KELLI F. KOLTYN,JOHNS.RAGLIN,JOELG.TURNER,ANDNED H. KALIN. Air travel across four time zones in college swimmers. J. Appl. Physiol. 70(Z): 756-763, 1991.-Eighteen female and 22 male college swimmerswere flown across four time zones in east-to-west (E-W) and west-to-east (W-E) directions. A preand postflight paced swim of 182.9m at an intensity equal to 90% of the swimmers’maximal velocity was completed, and salivary cortisol, heart rate (HR), and rated perceived exertion were measured. Blood pressure, HR, muscle soreness,and mood were also assessedat rest on the day before and on the day after travel. Becausetraining volumesfor both femalesand maleswere greater (P < 0.001) in the week before W-E than E-W travel, the W-E and E-W data were analyzed separately. Two-way repeated-measuresanalysesof variance revealedthat pre- and postexercise cortisol decreasedafter E-W travel and increasedafter W-E travel in comparison to preflight values. Resting and exercise HR responsesto air travel were small in magnitude, and their significancedependedon the direction of travel. Effort sensewasnot altered by air travel, but significant (P < 0.001) improvements in mood and reductions in muscle sorenesswere observed after E-W and W-E travel for both genders. It was concluded that 1) female and male college swimmershave similar responsesto air travel and 2) air travel across four time zones during heavy swim training does not have negative physiological, perceptual, or affective consequences. blood pressure; heart rate; mood; muscle soreness;perceived exertion; salivary cortisol

ATHLETES REGULARLY TRAVEL across multiple

time zones to participate in national or international competition, but little is known about the consequences of air travel for athletic performance. A number of reviewers (5,X&25,28) have surmised that transmeridian air travel exerts a transient detrimental effect on athletic performance. However, this position is not supported by systematic research involving athletes. The majority of related research has dealt with the effects of air travel on learning novel laboratory tasks, and this research has employed nonathletes as test subjects (8). Only a few investigators have directly examined the impact of air travel on athletic performance (1, 24), and a recent review (20) found the available research to be characterized by major methodological problems. It was concluded that 756

0161-7567191

$1.50

“no evidence exists in support of the view that rapid traversal of multiple time zones has an influence on athletic performance” (Ref. 20, p. 29). In contrast to athletic performance, physiological aspects of time zone transitions have been studied frequently. This body of research has focused primarily on assessing resting physiology (2)) and to our knowledge no published investigations have examined the effects of air travel on physiological responses to exercise in athletes. Exercise performance and performance-related cardiorespiratory variables have been assessed. before and after eastward travel across six time zones in male nonathletes (29). In this study the cardiorespiratory responses to graded treadmill running were not influenced by the flight, but significant reductions in distance and sprint running performance were observed after translocation. Even though the sample studied consisted of nonathletes, this investigation has frequently been cited inappropriately by reviewers as compelling evidence that athletic performance is reduced after air travel (5, 15, 25, 28). Empirical evidence addressing the question of whether air travel affects athletic performance to the same extent found in these nonathletes is lacking, but ample related evidence suggests caution in generalizing findings derived from nonathletes to athletes. For example, it is well established that athletes differ significantly from nonathletes in a wide variety of physiological and psychological variables measured at rest and during exercise. Similarly the responses of athletes to an environmental stressor such as air travel may differ significantly from those of nonathletes. Consequently the purpose of this investigation was to examine selected physiological and psychological parameters in a group of female and male college swimmers before and after air travel across four time zones. METHOD Subjects

Subjects were recruited from the University of Wisconsin-Madison men’s and women’s swimming teams. Each volunteer reviewed and signed an informed consent document before participation and was treated in accordance with the University’s human subjects guidelines. Complete data were obtained on a total of 18 females and 22

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AIR TRAVEL

757

AND SWIMMING

males. The age, height, and 63.6 t tics for the

females were characterized by a mean t SD and weight of 18.9 + 1.3 yr, 172.0 t 5.6 cm, 5.3 kg, respectively. These same characterismales were 19.3 t 1.3 yr, 184.7 t 5.6 cm, and 79.1 t 6.6 kg. Travel

The subjects were initially flown from Madison, Wisconsin, to Honolulu, Hawaii (i.e., east-to-west; E-W). The date of departure for half of the participants was 22 December 1988, and the remaining subjects departed 2 days later. These flights left Madison at 0720 h local time, had stopovers of -45 min in Minneapolis and Los Angeles, and arrived in Honolulu at 1545 h local time. Thus the total transit time was 12 h 25 min. The return flight for all subjects left Honolulu at 1720 h local time on 16 January 1989 and arrived in Madison at 0900 h local time on 17 January. This west-to-east (W-E) flight included a 1 h 40 min layover in Minneapolis, which made the total time in transit 11 h 40 min. Training

The swimmers completed daily swim training before and after the translocations, and its intensity, frequency, and duration were regulated by the coaching staff. During the week before E-W travel, the female and male groups were swimming on average 6,750 t 430 and 8,800 t 365 m/day, respectively. Training was reduced to 3,500 m on the day before travel for both groups, and no training was performed on the day of travel. During the week preceding W-E travel, the swimmers were training significantly more than in the week before E-W travel, and the training volume before W-E travel averaged 10,880 t 460 and 12,710 t 450 m/day, respectively, for the female and male groups. On the day that W-E travel was initiated, training was reduced in both groups to 6,950 m. The swimmers did not train on the day the W-E flight arrived in Madison. On the mornings of the day following travel in either direction, regular training was resumed with a workout of 5,OOO-5,500 m. Dependent Measures

Assessments of the dependent variables were made before and after the E-W and W-E flights. Swim tests were performed during the week before and l-2 days after each flight. Variables studied during the resting state were assessed on the day before and after air travel. All measurements were made between 1300 and 1500 h local time before the onset of a scheduled swim practice. Swim test. Each swimmer performed a total of four 182.9-m swims (i.e., pre- and postflight tests in both travel directions) in his/her specialty stroke from a push-off start. The swim tests were preceded by a warmup of -1,300 m at a pace chosen by the swimmer. Microcomputer-controlled pacing lights (Pacer Products) were placed in the line of sight to ensure that the swimmers maintained a pace equal to 90% of their maximal velocity. Stroke classifications and times for one of the swim tests are presented in Table 1. Because the number of subjects in each of the four swimming stroke categories was small, the data were collapsed across the four stroke

1. Stroke classifications and times for swim test at 90% of maximum velocity performed before E-W flight TABLE

Stroke

Butterfly Backstroke Breaststroke Freestyle

Females

147.0t1.4 147.0to.o 168.7k4.9 133.0t5.5

Males

(2) (1) (5) (10)

132.6t2.2 129.8t3.9 151.9k5.2 121.3t6.4

(2) (3) (7) (10)

Values are means k SD of no. of subjs in parentheses expressed in s/182.9 m.

categories for analytic purposes. The following variables were measured in association with the swim test. HEART RATE. Heart rate (HR) was assessed using Uniq HR monitors (model PE 3000 SE). Two electrodes and a waterproof transmitter were affixed to the chest of each swimmer. HRs were averaged across 15-s intervals and stored in a microcomputer placed in the swimmer’s suit. The mean HR for the final minute of the swim was employed for criterion purposes. SALIVARY CORTISOL. Fifteen to 20 min before each swim test, the subjects rinsed their mouths with water and then provided -4 ml of saliva directly into a test tube. One minute after the exercise tests, the swimmers exited the pool, rinsed their mouths with water, and gave a second 4-ml sample of saliva. All subjects provided an adequate saliva sample within 4 min. The samples collected in Madison were stored in a freezer maintained at -7O*C within 2 h of collection. The samples collected in Honolulu were frozen at -4*C within 2 h of collection for 1 wk. These samples were subsequently packed in dry ice, flown to Madison, and stored at -7O*C for 30-60 days. All the samples were thawed and then centrifuged at 4,172 g for 20 min. After centrifugation, 200-~1 saliva samples were aliquoted. These samples, from which cortisol would later be assayed, were then refrozen at -7OOC. Kahn et al. (11) have demonstrated that salivary cortisol levels are not influenced by storage of samples at room temperature, 4”C, or -7OOC. Therefore it is unlikely that the different storage protocols for the E-W vs. W-E samples have introduced systematic bias. Salivary cortisol was assessed using Rianen cortisol 1251radioimmunoassay kits (DuPont). The assay procedures followed the manufacturer’s instructions except for minor modifications to increase the sensitivity of the assay for measuring cortisol in saliva. The primary modification was that 200-~1 samples were utilized rather than the lo-p1 samples that are called for in the assay for serum cortisol. A number of investigators have employed this approach to increase assay sensitivity, because cortisol in saliva is m 10% of the concentration found in serum (11,21,27). The sensitivity, or minimum detectable dose of cortisol in saliva that could be detected at a 95% level of confidence, was 0.059 t 0.038 (SD) pg. The betweenassay coefficients of variation were 7.4 and 5.2% for the low and high reference samples, respectively. Samples were run in duplicate, and all values that were >2 SD above the mean intra-assay coefficient of variation for any single run were repeated. The resultant overall intra-assay coefficient of variation was 6.0 t 2.0%. PERCEPTION OF EFFORT. Overall and local (i.e., arm)


758

AIR

TRAVEL

AND

ratings of perceived exertion (RPE) were obtained immediately after the completion of the swim tests by use of Borg’s 6-20 scale (4) and an experimental seven-point category scale with the following verbal anchors: 1 = very very easy, 2 = very easy, 3 = easy, 4 = average, 5 = hard, 6 = very hard, and 7 = very very hard. The swimmers were given standardized instructions in the use of the perceptual scales (4). The experimental scale has been previously employed to assess perception of effort in college swimmers (18), and it was used in conjunction with the Borg scale in the present study to determine the relationship between the two instruments. SLEEP, BLOOD PRESSURE, AND HEART RATE. The previous night’s sleep onset latency and total hours slept were quantified through questions imbedded in a 24-h history. Blood pressure and HR were assessed with Marshall electronic digital blood pressure and pulse monitors (model 89) after 10 min of seated rest. This device assesses blood pressure by an oscillometric method, which has been shown to be highly correlated with both intra-arterial (t = 0.74-0.89) and sphygmomanometer (r = 0.980.99) methods (9). MUSCLE SORENESS. Muscle soreness was measured using a seven-point category scale with the following verbal anchors: 1 = very very good, 2 = very good, 3 = good, 4 = tender but not sore, 5 = sore, 6 = very sore, and 7 = very very sore. Separate ratings of muscle soreness were obtained on four upper body (i.e., chest, forearms, upper arms, and shoulders) and four lower body (i.e., quadriceps, hamstrings, calves, and shins) muscle groups. Overall ratings of muscle soreness were also made. This scale has previously been shown to be sensitive to alterations in the training volume of swimmers (18). MOOD. Mood was measured using a standard psychometric measure, the Profile of Mood States (POMS) questionnaire (16), which assesses tension, depression, anger, vigor, fatigue, and confusion. A composite measure of mood (i.e., overall mood state) was also computed by summing the five negative mood variables, subtracting the vigor score, and adding a constant of 100 to avoid negative numbers. Thus the greater the overall mood score was, the worse the mood. There are four response sets typically used with the POMS, and in this study the “today” set (i.e., “How are you feeling today?“) was employed. Response distortion, such as the tendency for certain individuals to respond to questionnaires in a socially desirable rather than a truthful way, was assessed using the “lie scale” imbedded in the Eysenck Personality Questionnaire (7). A battery of psychometric questionnaires including the Eysenck Personality Questionnaire was administered at the outset of the training season to obtain baseline psychometric data and assess response distortion. Three female and two male swimmers were deleted from the investigation before any statistical analyses were performed because of elevated lie scores. Statistical

Analyses

Descriptive statistics were computed for all the dependent variables. A series of two-way repeated-measures analyses of variance was employed for analytic purposes.

SWIMMING

Separate analyses were conducted for each travel direction because of the differences in training volume observed during the week before E-W vs. W-E travel. A Bonferroni procedure (22) was adopted to maintain the overall type I error at 0.05. Because of the large number of ANOVAs performed, this procedure resulted in a P value of 0.001 being required for any individual ANOVA to reach statistical significance. RESULTS

AND DISCUSSION

Sleep Values and F ratios for the sleep data are presented in Table 2. Female and male swimmers slept significantly (P < 0.001) longer on the night after W-E but not E-W travel. The increase in total sleep time after W-E air travel averaged 68 min for the combined female and male group (n = 40). Significant main effects for gender were not observed, nor were gender X trial interactions significant. Sleep onset latency was characterized by large variability, with the standard deviations approximately equal to the group means. This finding is consistent with previous reports of large variability in sleep onset data in studies in which sleep onset was examined using electroencephalographic criteria (10). A significant (P < 0.001) main effect for the trial factor was found in association with W-E travel, and the swimmers reported falling asleep more quickly after the W-E flight than on the night before travel. Although neither the main effect for gender nor the gender X trial interaction was statistically significant, this change was more pronounced for the females, and their sleep onset latency decreased on average by 15.4 min after the W-E flight. The findings for both total sleep and sleep onset latency are generally consistent with previous research in which the effects of air travel across time zones on sleep were examined in samples of nonathletes. This prior research has demonstrated, for example, that sleep patterns are influenced to a greater extent after air travel in a W-E direction than after E-W flights of the same distance (6). Interpretation of the sleep data was confounded because of the reduced training associated with air travel. Although the effects of short-term reductions in training on sleep have not been well studied, sleep disturbances have been found in trained subjects deprived of their usual exercise (10). Thus the current results are possibly due to reductions in training rather than air travel per se. The fact that air travel in both directions was associated with a significant reduction in training also confounds the interpretation of the results for every other variable examined in the present study. However, athletes must typically alter training schedules when flying across multiple time zones. That is, even when athletes are not engaged in heavy training immediately before translocation, disruptions in training, sleep, and dietary regimens are an integral component of lengthy flights, and these factors may have effects independent of those due to air travel per se. Thus, firm conclusions concerning the effects of air travel per se on athletes will require a systematic research effort that separates out the effects


AIR TRAVEL TABLE

759

AND SWIMMING

2. Sleep, resting heart rate, and blood pressure data Blood Sleep Sleep,

h

Onset, min

Heart Rate, beats/min

Systolic

Pressure,

mmHg Diastolic

E-W

Females Preflight Postflight Males Preflight Postflight F ratio Gender Trial Gender X trial

6.5tl.l 7.1t1.2

10.9*9.1 17.5t21.3

74.8k6.5 77.1t7.7

120.5t8.9 117.827.9

68.9k6.0 64.5t7.2

6.8t1.2 7.4t0.8

17.0k16.2 12.OH1.3

68.6t8.8 71.3t8.2

132.7kl3.0 134.Od3.4

70.7t9.1 72.029.2

1.8 6.6 0.1

0.5 0.2 5.1

9.0 13.9* 0.4

19.1" 0.2 1.6

4.2 1.6 5.5

W-E


6.8t0.6 7.6t1.3

25.9t24.5 10.5tlO.O

70.6t8.5 74.2t9.1

117.2t10.4 126.5t10.3

63.9k7.1 72.6k7.6

6.6t0.8 8.0t2.2

ll.Ot11.5 9.9t8.6

7O.lk6.0 68.6k9.7

139.2kl3.9 137.2t12.7

70.2t8.6 74.0t7.9

0.2 12.3* 0.9

3.9 10.9* 8.3

2.3 0.4 4.5

27.3* 2.7 6.6

8.1 0.7 0.2

Values are means t SD. *Statistically

significant effect (P < 0.001).

of a host of variables known to change in association with translocation. Resting Heart Rate and Blood Pressure

Values and I+’ ratios for the resting HR and blood pressure data are presented in Table 2. Air travel was not associated with changes in systolic or diastolic blood pressure. However, a significant (P < 0.001) main effect for gender was found with systolic pressure regardless of travel direction. At each measurement period, systolic blood pressure was greater for the males than the females. Although both groups were normotensive, this finding is generally consistent with epidemiological reports indicating that hypertension is more prevalent in males than in females (23). Gender X trial interactions were not significant for either systolic or diastolic blood pressure. A significant (P < 0.001) main effect for the trial factor was observed with E-W but not W-E travel for resting HR. After E-W air travel, both the females and males exhibited similar elevations in resting HR, and the increase for the combined group averaged 2.5 beats/min. Neither the main effects for gender nor the gender X trial interactions were significant in the case of resting HR. A mechanism for an increased resting HR with E-W travel only cannot be determined on the basis of the results of the present study, and regardless the magnitude of the alteration was not large. Exercise Heart Rate

A main effect for the was found for exercise After W-E travel, both in exercise HR, and the

trial factor (F = 11.9, P < 0.001) HR in the W-E travel direction. sexes exhibited similar increases values for the combined group of

female and male swimmers were 160.3 t 7.1 (preflight) and 164.5 t 5.9 beats/min (postflight). The exercise HR did not change significantly after E-W travel, and the corresponding values were 167.7 t 6.8 (preflight) and 164.9 -t 6.4 beats/min (postflight). Main effects for gender and gender X trial interactions were also not significant for exercise HR in either direction. It is not clear why alterations in exercise HR were observed after the W-E flight only, and these data are inconsistent with the results of Wright et al. (29), who showed that preflight submaximal HR did not differ from postflight values. Nevertheless, as with resting HR, exercise HR responses to air travel were relatively small in magnitude. Salivary Cortisol

Values and F ratios for the cortisol data are given in Table 3. The preexercise salivary cortisol levels were found to be comparable to values reported previously for female swimmers (21) and highly fit male subjects (19). Air travel across four time zones was associated with significant (P < 0.001) changes in salivary cortisol levels, and the direction of change differed depending on the direction of travel. Compared with preflight values, preexercise salivary cortisol levels were reduced after EW travel but increased after W-E travel. The same pattern of response was also observed for postexercise salivary cortisol. Although this study was not desi gned to examine mechanisms for the changes observed after air travel, it can be bP lothesized th .at the findings for corti sol may be seco ndarY to the fact that postfligh .t saliva samples were obtained at a time representing a 4-h advance or delay in relation to the circadian phase at which the preflight samples were taken. Results from previous investigations in


760 TABLE

AIR TRAVEL

AND SWIMMING

3. Salivary cortisol data Preexercise

Postexercise

E-W


0.35t0.14 0.25t0.19

0.30t0.12 0.18~0.11

0.25t0.14 0.13*0.08

0.15t0.09 0.11t,0.08

9.9* 12.9* 0.1

30.4* 16.9* 4.5

W-E


0.2420.12 0.34t0.15

0.14t0.08 0.23t0.10

0.15kO.07 0.23kO.11

0.12kO.09 0.15t0.10

16.2* 14.8" 0.1

6.8 13.9* 4.7

Values are means f SE expressed in pg/dl. *Statistically effect (P < 0.001).

significant

which serial cortisol measures have been obtained for 24-h periods before and after E-W and W-E air travel (13) support this potential explanation for the present findings. Alternative explanations for the cortisol results appear to be less plausible. For example, because training was reduced in association with both flights, the cortisol changes are unlikely to be the result of a short-term decrease in training. Similar reasoning argues against the findings being closely linked to alterations in psychological distress. That is, even though cortisol has previously been shown to be correlated with depression in female swimmers during heavy training (Zl), depression levels decreased in association with air travel in both directions but changes in cortisol levels depended on the travel direction. Three of the four ANOVAs used to analyze the cortisol data revealed significant (P < 0.001) main effects for gender. Also, at every trial the mean salivary cortisol concentration for the females was greater than that for the males. The reason for this is not clear. Systematic changes in cortisol across the menstrual cycle have not been demonstrated in a compelling manner. It is, however, known that contraceptive medications can elevate salivary cortisol by lowering cortisol-binding proteins in the blood (27), but none of the swimmers in the present investigation reported use of oral contraceptives. Nevertheless the changes in preexercise salivary cortisol as well as the cortisol responses to exercise observed in association with air travel were similar between the females and males. Although the postexercise salivary cortisol levels were somewhat decreased compared with the preexercise values, for each of the four swim tests, the changes were not significant for any trial. Thus the cortisol response to exercise was not influenced by either W-E or E-W travel.

These findings are generally consistent with previous research in which no significant alteration in serum cortisol levels has been reported in response to a 365.8-m front crawl swim at 95% of maximal aerobic capacity in male college swimmers (12). Perception of Effort

Neither main effects nor the gender X trial interactions were significant for any of the perceived exertion variables. For the combined group of female and male swimmers the overall RPE values (6-20 scale) in association with air travel in the E-W direction were 13.5 t 1.8 (preflight) and 13.8 t 2.0 (SD) (postflight). The corresponding values for the W-E flight were 14.8 t 2.4 (preflight) and 14.7 t 1.8 (postflight). The higher RPE values before the W-E flight are consistent with the greater training load performed in the week before W-E travel. For the Borg and the experimental seven-point scales, the findings for local RPE were not significantly different from those observed for the overall assessments. The perception of effort has not heretofore been studied in competitive swimmers before and after transmeridian travel. However, the finding that air travel across four time zones was associated with no changes in RPE during paced swims is not consistent with expectations based on previous research. Wright et al. (29), for example, found that postflight RPE values (9.8 t 0.7) were lower than preflight values (11.1 t 0.7) in soldiers translocated across six time zones, and O’Connor and Morgan (20) have reported that this difference of 1.3 RPE units was statistically significant (P < 0.05). The reason for the discrepancy between the present findings and the study of Wright et al. (29) is unclear, but it may be accounted for by a number of factors including differences in subjects studied (athletes vs. nonathletes), exercise mode (swimming vs. treadmill running), exercise intensity, or the number of time zones traversed (4 vs. 6). The seven-point experimental scale yielded results comparable to those found with Borg’s 6-20 scale. Pearson correlations were computed between the two scales for the combined female and male sample. Significant (P < 0.001) correlations were found at each trial between the two scales for both overall and local RPE ratings. These correlations did not differ significantly from trial to trial and ranged from r = 0.78 to 0.94. The mean correlation across the four trials between the traditional 6-20 Borg scale and the seven-point experimental scale was found to be r = 0.89 for overall RPE and r = 0.91 for local RPE. These correlational analyses provide concurrent validity for the experimental seven-point RPE scale. This study is part of a more comprehensive effort designed to establish the construct validity of several perceived exertion scales. Although Borg’s 6-20 scale is the most widely used perceived exertion scale, its verbal anchors are less than ideal in terms of semantic consistency; they range from “light” to “hard,” rather than “light” to “heavy,” or “easy” to “hard.” The seven-point scale eliminates this semantic inconsistency, and unlike Borg’s 6-20 scale it makes no assumptions about the relationship between the physical stressor (i.e., exercise intensity) and strain


AIR

VI cn

TRAVEL

AND

6

W

Z

1,

w 5 DC

0 VI 4 I -I < DC

W >

SWIMMING

761

than to air travel. Second, in the study of Wright et al., subjects flew across six time zones, whereas the present study involved translocation across four time zones. It is possible that traversal of time zones does not have an effect until a specific threshold number of time zones is reached, and previous research supports this idea for a number of physiological variables (2, 13). Third, and the most likely explanation in our view, air travel in the present study was associated with a significant reduction in training, whereas the subjects in the investigation described by Wright et al. were not physically training before travel.

3 .

Mood

0 2

EAST ‘-WEST

WEST-EAST

1. Overall muscle soreness levels in female and male college swimmers (n = 40) before (Cl) and after (H) east-west and west-east air travel across 4 time zones. FIG.

(i.e., heart rate). This HR-RPE relationship on which Borg’s 6-20 scale is based is known to be low or nonexistent in certain circumstances, such as with individuals taking P-blockers. Also, in the present study, nonsignificant correlations were found between RPE and exercise HR for both the seven-point and the 6-20 scales. Muscle Soreness

Significant (P < 0.001) main effects for trials were observed with both E-W and W-E travel for the muscle soreness variables. Air travel in both directions was followed by a reduction in muscle soreness for each of the individual muscle groups as well as for overall soreness levels. Because neither the main effects for gender nor the gender X trial interactions reached significance, representative muscle soreness findings (i.e., overall soreness) for the combined group of female and male swimmers are presented in Fig. 1. The absolute magnitude of the reduction in overall soreness was significantly greater after W-E than E-W travel. This finding can be accounted for in part by preflight differences in soreness level, because, for example, the overall soreness level before the W-E flight was significantly greater than that observed on the day before the E-W trip. The higher muscle soreness values found on the day before the W-E flight, however, were consistent with the greater training volume performed during the week before travel in this direction. The finding of reduced muscle soreness with air travel is not in agreement with observations of Wright et al. (29), who reported elevated muscle soreness after W-E air travel across six time zones in military personnel. The present investigation differed from this previous study in three ways, any of which might account for the discrepant findings. First, Wright et al. required male subjects who were unaccustomed to regular exercise to perform strenuous exercise tests on 5 consecutive days before travel. Thus the increased muscle soreness levels they reported may have represented delayed-onset muscle soreness consequent to the exercise testing per se rather

Values and F ratios for the mood states are presented in Table 4, and the overall mood data for the combined female and male group are displayed in Fig. 2. For each of the six specific mood states measured by the POMS as well as for overall mood, significant (P < 0.001) main effects were found for the trial factor. Mood states improved after air travel in either W-E or E-W direction. Main effects for gender and gender X trial interactions were not significant except for tension. The females were characterized by significantly greater tension levels than the males before E-W travel (gender F = 11.3,P < 0.001). Despite this difference in tension, the genders responded to air travel in a similar fashion for each mood variable. The preflight mood state of the swimmers was significantly disturbed compared with a baseline measure of mood obtained at the outset of the training season. Before travel in either direction the overall mood of the swimmers was elevated by >l SD compared with the baseline values, which were 128.5 t 26.4 for the females and 118.7 t 25.4 for the males. Baseline data were obtained when the training volume for both female and male swimmers was +OOO m/day. Because the presence of mood disturbances during heavy training in college swimmers has been well established (17), the elevated preflight mood values are not surprising, given the training load endured by the swimmers in the week before travel. A number of explanations are possible for the large mood shifts observed in association with air travel. One might argue, for example, that mood improvements are to be expected with wintertime travel to a desirable destination such as Honolulu. However, this reasoning fails to account for the similar mood improvements exhibited after travel away from Hawaii. The mood results of the return trip from Honolulu to Madison might be accounted for by a second separate hypothesis, such as the idea that mood improved because the swimmers were homeward bound. However, previous research does not support this reasoning, because it has been demonstrated empirically that the origin and destination (i.e., outward vs. homeward bound) of flights have little bearing on the consequences of air travel (14). In our view, the most plausible explanation for the mood improvements observed after air travel is the fact that travel was associated with a reduction in training. That is, the flights provided the swimmers with a respite from heavy training. This view is consistent with previous reports of mood


762

AIR TRAVEL AND SWIMMING

TABLE 4. Profile of Mood States Data Tension

Depression

Anger

Vigor

Fatigue

Confusion

Overall

E-W

Females Preflight Postflight Males Preflight Postflight F ratios Gender Trial Gender X trial

19.129.2

9.7k4.5 12.4k5.4

5.9k3.4 11.3* 58.5* 1.9

15.1t9.2 7.1k6.7

12.2k9.0 5.924.8

10.8t5.4 16.2t6.3

15.4t7.0 9.3k4.9

11.7t5.0 6.1t3.5

164.4k33.3 119.3t24.3

12.3t6.5 6.126.0

12.9tlO.l 4.9t3.9

10.4t5.1 14.7t6.5

13.7t6.2 7.8t4.7

10.7t3.3 6.9t2.7

151.6k29.6 114.5k18.2

0.1 25.8* 0.4

0.5 15.1* 0.2

1.4 23.3* 0.1

0.1 57.0* 2.2

2.1 47.5* 0.5

162.2t32.1 130.6+_30.0

1.1 23.1* 0.4

W-E


13.9t6.3 9.926.2

10.2t7.8

8.9t9.2

1 l.Ot4.9 15.1t5.2

16.4t6.0 8.9t5.3

9.5t4.4 7.6k4.8

10.125.2 5.5k4.0

11.7t9.5 5.6k7.2

ll.lt8.4 4.Ok5.0

9.Ok4.0 12.8k5.9

15.6k5.7 8.7t5.2

10.4k4.2 6.2t4.4

2.3 18.0* 0.6

5.7 33.7* 0.2

2.5 23.0* 0.1

0.1 72.4* 0.1

0.4 25.4* 3.7

7.3

26.9* 0.1

14.3t8.9

17.3+ 10.8

Values are means +, SD expressed in raw score units. *Statistically

improvements after reductions in training (N), and it accounts for the results observed for both travel directions. Furthermore the differences in training can also reconcile the finding of mood improvements associated with air travel in this study and reports of mood disturbances following air travel across 6-11 time zones in nonathlete test subjects (3, 28). Thus the present findings are contrary to the view expressed by a number of previous authors that transmeridian translocation results in negative mood shifts (1, 3, 28) and demonstrate that air travel is not necessarily associated with mood disturbances. Indeed, the athletes in this study experienced positive changes in mood state with air travel across four time zones. This finding, how-

(f) z

180

0 CL

170

-

160 n 0

150

02

140

T

EAST-WEST

WEST-EAST

2. Overall mood state levels evaluated by Profile of Mood States (POMS) in female and male college swimmers (n = 40) before (Cl) and after (m) east-west and west-east air travel across 4 time zones. FIG.

149.5t25.5 117.5k21.7 2.7 74.1* 0.1

significant effect (P 5 0.001).

ever, may be specific only to athletes who travel during a period of intense training. Conclusions. On the basis of the results of this study, it is concluded that female and male college swimmers respond similarly to air travel across four time zones. Although some gender differences were observed, such as a higher systolic pressure in the males, the changes in each of the dependent variables that occurred with air travel were comparable between the sexes. Although there was no theoretical rationale for hypothesizing differences between females and males in their responses to air travel, this possibility was tested because the related literature concerning air travel and physical performance has employed males alone as test subjects. Second, it is concluded that negative physiological, perceptual, and affective changes do not occur in female and male college swimmers after translocation across four time zones during heavy training. This view contradicts the statements of previous authors who have, in our view, inappropriately concluded and/or assumed that transmeridian air travel has negative effects on athletes and their performance (5,15,25,28). Indeed, the idea that air travel has negative effects is so pervasive that numerous strategies have been suggested for minimizing “jet lag” to improve athletic performance (5, 25). These include dietary and environmental manipulations as well as early arrival in a new time zone in order to acclimatize. These recommendations, however, appear to be premature because of a paucity of data concerning the effects of air travel in athletes and because neither Davis (5) nor the US Olympic Committee (25) presents a scientifically defensible research basis for the efficacy of their recommendations. Anecdotally, it is interesting to note that contrasting recommendations have been expressed by animal trainers. For example, Dermot Weld, trainer of “Go and Go,” the Irish-bred horse that won the 1990 Belmont Stakes by 8.25 lengths 2 days after a trans-Atlantic


AIR TRAVEL

AND SWIMMING

flight, insists that horses run best if they compete as soon as possible after translocation. “Acclimatization just doesn’t work,” Weld said. “Look at the Breeders Cup and how poorly the European horses have done. I’ve learned it works best to cut it as close as possible” (MGsconsin State Journal Newspaper, 10 June 1990, p. 9E). The results of the present investigation also underscore the need for systematic research in this area, because the findings are diametrically opposed to the prevailing view held by most athletes, coaches, and exercise scientists. Lastly, the present findings also highlight the need for taking changes in training into account if the effects of translocation in athletes are to be fully elucidated. Previous investigators had no reason to examine alterations in training in conjunction with air travel because athletes were not studied. However, changes in training that occur in association with air travel can represent a significant alteration in the customary training program of athletes and thereby confound effects of translocation per se. Because short-term changes in training have previously been shown to have significant physiological and psychological effects (12,17,18), it is imperative that future jet lag research on athletes control for both preand postflight training schedules. We thank the members of the 1988/89 University of WisconsinMadison swimming teams for their participation in the study; coaches John D. Pettinger and Carl E. Johansson for cooperation throughout the project; Dr. Jan H. Prins, Director of the Aquatic Research Laboratory at the University of Hawaii at Manoa, for providing laboratory space and support in Honolulu; and Polly Norton for expert technical assistance during testing in Madison. This investigation was funded by the Sports Medicine Council of the US Olympic Committee. Address for reprint requests: P. J. O’Connor, Exercise and Sport Research Institute-PEBE 210, Arizona State University, Tempe, AZ 85287-0404. Received 2 July 1990; accepted in final form 19 September 1990. REFERENCES L. C. The effects of the changes of the circadian body rhythm on the sportshooter. Br. J. Sports Med. 9: g-12,1975. ASCHOFF, J., K. HOFFMAN, H. POHL, AND R. WEVER. Re-entrainment of circadian rhythms after phase-shifts of the zeitgeber. Chronobiologia 2: 23-78, 1975. BASSETT, J. R., AND R. SPILLANE. Urinary cortisol excretion and mood rating in aircraft cabin crew during a tour of duty involving disruption in circadian rhythm. Pharmacol. Biochem. Behau. 27: 413-420,1987. BORG, G. A. V. Perceived exertion: a note on “history” and methods. Med. Sci. Sports Exercise 5: 104-109, 1973. DAVIS, J. 0. Strategies for managing athletes’ jet lag. The Sport Psychol. 2: 154-160,1988. ENDO, S., T. YAMAMATO, AND M. SASAKI. Effects of time zone changes on sleep. In: Advances in Sleep Research. Biological Rhythms, Sleep, and Shiftwork, edited by L. C. Johnson, D. I. Tepas, W. P. Colquhoun, and M. J. Colligan. New York: Spectrum, 1979,‘p. 415-434. EYSENCK, H. J., AND S. B. J. EYSENCK. Eysenck Personality Questionnaire. San Diego, CA: Educational and Industrial Testing Service, 1975. GRAEBER, R. C. Alterations in performance following rapid trans-

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Vertigo following air travel.

Air travel and pneumothorax.

Medical hazards of air travel.

Helping patients travel by air.

Medical hazards of air travel.

Medical hazards of air travel.

Medical hazards of air travel.

Medical hazards of air travel.

Mental time travel for self and other in three- and four-year-old children.

Genetic Time Travel.

Sleep, Travel, and Recovery Responses of National Footballers During and After Long-Haul International Air Travel.

Identifying Optimal Overload and Taper in Elite Swimmers over Time.

Safety of early air travel after treatment of traumatic pneumothorax.

AsMA Medical Guidelines for Air Travel: stresses of flight.

Air travel considerations for the patients with heart failure.

Children's mental time travel during mind wandering.

An Allais paradox without mental time travel.

Network structure and travel time perception.

Consciousness minus retrospective mental time travel.

Marital Name Changing Attitudes and Plans of College Students: Comparing Change Over Time and Across Regions.

Middle-ear pain and trauma during air travel.

Air travel and patients with pulmonary and allergic conditions.

Massive Ischemic Stroke Due to Pulmonary Barotrauma and Cerebral Artery Air Embolism During Commercial Air Travel.

Changes in mood states during training in female and male college swimmers.