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Applied Sciences: Psychobiology And Social Sciences

Impact of rapid weight loss on cognitive function in collegiate wrestlers

CHOMA, CELESTE W.; SFORZO, GARY A.; KELLER, BETSY A.

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Medicine & Science in Sports & Exercise: May 1998 - Volume 30 - Issue 5 - p 746-749
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Abstract

Rapid weight loss (RWL), also known as “weight cutting,” has received attention from both the American College of Sports Medicine(1) and the American Medical Association(2); both created position statements that oppose this practice. RWL typically involves self-induced dehydration and starvation until target weight is met; it is commonly practiced before competition by a variety of athletes (4,10). During a season, wrestlers may repeatedly endure this routine of losing and regaining between 3.1 and 9.5 kg(6). RWL can greatly diminish plasma volume acutely straining cardiovascular, thermoregulatory, and renal function(13,18,22,25). It is also reasonable to project that RWL can lead to hypoglycemia.

Neuroglycopenia, secondary to hypoglycemia, describes an impairment in cognitive function that is observable in both normal(7,17) and diabetic(21,27) subjects. It is unknown whether RWL in athletes can lead to neuroglycopenia as no prior reports have studied cognitive function, hypoglycemia, or hypoglycemic symptomology. It is conceivable, however, that the adverse physiological effects of RWL may have negative cognitive, behavioral, or psychological consequences. This is an important issue, given that the majority of athletes practicing RWL are college and high school students who can ill afford to suffer neuroglycopenia, albeit transiently.

Research involving elementary school children suggests that cognition may be maintained in highly motivated individuals during symptomatic hypoglycemia(8,20). Accordingly, it may hypothesized that, even if RWL produces transient hypoglycemia, cognitive function in highly trained competitive athletes may not suffer. As professionals with an interest in both education and sports medicine, it is incumbent on us to examine the potential extended effects of RWL on the intellectual, social, and emotional domains of our student-athletes. Therefore, the purpose of this study was to determine whether RWL affects cognitive function and mood state in collegiate wrestlers during the competitive season.

METHODS

Subjects. Twenty-nine college-aged males participated in this study. Wrestlers (N = 14) were competitive for a minimum of 3 yr before the study, and controls (N = 15) were off-season athletes who trained at least 5 d·wk-1. Control subjects were of stable weight (± 4.5 kg in the previous 3 months) and were not intentionally attempting to lose or gain weight during the study. Table 1 provides details of subject characteristics. Subjects each signed an informed consent form detailing the procedures and purposes of the study as approved by the Institutional Review Board for Human Subjects Research.

T1-16
TABLE 1:
Subject characteristics.

Baseline data. All subjects visited the laboratory twice to practice the cognitive test battery and give baseline blood samples. Only those in normal range and stable (<10% difference between the two visits) for glucose, hemoglobin (Hgb), hematocrit (Hct), and plasma volume (PV) were used as subjects in the study. Baseline for glucose, Hgb, Hct, and PV were an average of the two values obtained during these two preliminary meetings.

RWL and rehydration data collection. Baseline data were collected approximately 1 wk before the commencement of the wrestling season. RWL data were measured immediately after an official weigh-in and 18-24 hr before competition. A minimum of 5% body weight loss was required before RWL data were collected on any subject. Decrements in physical performance and physiological effects occur when RWL exceeds 5% of body weight(11,13,26). The practice of “weight cutting” typically commenced 12 to 36 hr in advance of weight-in, depending on the amount of weight the wrestler expected to lose. Food and fluid consumption resumed after completion of the RWL data collection. Rehydration data were collected approximately 72 hr after weigh-in and at least 48 hr before implementing “cutting” techniques for subsequent competition.

Data collection for control subjects mirrored that of the wrestlers; however, they did not practice RWL, were of stable weight, and maintained normal food and fluid consumption throughout the study. For all subjects, body composition was determined before and after the wrestling season by underwater weighing using an oxygen dilution technique to correct for residual lung volume.

Testing procedures. Cognitive testing procedures were conducted in a quiet environment with identical conditions and test sequencing during baseline, RWL, and rehydration data collection. Testing commenced with the profile of mood states (POMS-R; EdITS, San Diego, CA) and the hypoglycemic profile (21) scales. This was followed by the cognitive test battery which consisted of five short tests requiring approximately 12 min to complete. Test order was not randomized to help assure consistency in the testing environment.

The cognitive battery included letter cancellation, a test of visual attention and visuomotor skills (16); digit symbol and digit span, tests of attention and short term memory (STM) which are subtests of the Wechsler Adult Intelligence Scale-Revised and Memory Scale, respectively (Psychological Corporation, San Antonio, TX); trailmaking A and B, to assess visual acuity, visuomotor, and attention skills(16); and story recall, which assesses STM and is a subtest of the Wechsler Memory Scale. To minimize any potential learning effect, three different versions of the cognitive test battery were administered in counterbalanced order during the three testing sessions. Thus, subjects received a different version of the cognitive test battery at each session. This cognitive battery was selected for brevity, ability to assess a range of cognitive functions, and documented sensitivity to hypoglycemia(7,17,27).

At each testing session approximately 3 mL of blood were collected via an antecubital vein for determination of Hct, colorimetric analysis of Hgb, and subsequent calculation of PV using the formulae of Dill and Costill(9). Blood glucose was determined from a capillary blood sample using a rapid analyzer (Boehringer Mannheim, Indianapolis, IN).

Statistical Analyses. Two-way ANOVA with one repeated measure were used to compare cognitive tests, mood state, hypoglycemic profile, blood glucose, PV, body weight, and body composition between wrestlers and control subjects at baseline, RWL, and rehydration. Significant interactions were inspected with t-tests to locate between group differences at each time (P < 0.05). A Bonferroni adjustment was used for the six subscales of the POMS-R establishing alpha at P < 0.008 for these analyses.

RESULTS

Body weight and composition. The body weight of control subjects who did not practice RWL remained relatively stable throughout the study. Wrestlers had a lower body fat percentage than controls (7.8 vs 10.9% fat) and this difference was essentially the same before and after the wrestling season. Body weight was 5.1 kg lower after RWL in wrestlers representing a 6.2% average loss in body weight.

Cognitive test battery. Significant group × time interactions were found for the digit span and story recall tests. With both subtests, wrestlers scored significantly lower than control subjects after RWL(Table 2). Letter cancellation, digit symbol, and trailmaking A and B tests did not reveal any significant between group differences over the three testing sessions.

T2-16
TABLE 2:
Selected cognitive and physiological data at three time points for wrestlers and controls.

Mood state profile. Significant group × time interactions were found for five of the six POMS-R scales as displayed inFigure 1. The mood state of wrestlers was more negative(P < 0.008) than that of controls after RWL. Wrestlers returned to baseline mood state following rehydration, whereas control subjects maintained a relatively stable mood state throughout the study.

F1-16
Figure 1-POMS-R scores for wrestlers and control subjects at baseline, RWL, and rehydration for each of the six scales. T-A: tension-anxiety; D-D: depression-despair; A-H: anger-hostility; V-A: vigor-activity; F-I: fatigue-inertia; C-B: confusion-bewilderment. Values are means ± SD. **:
P < 0.008; (Bonferoni adjusted)

Blood analyses and hypoglycemic profile. Significant group× time interactions were found for both hypoglycemic profile and blood glucose measurements. Wrestlers experienced a lower blood glucose(Table 2) and greater hypoglycemic symptomology after RWL than control subjects. After RWL, wrestlers had blood glucose levels that were 13.7 mg·dL-1 lower and hypoglycemic profiles that were 37% greater than at baseline. Whereas in controls who did not experience RWL, blood glucose varied only 3.13 mg·dL-1 with no change in hypoglycemic symptomology.

As expected, a significant group × time interaction was also found for PV. PV of wrestlers dropped 11.0% with RWL, but returned to baseline following rehydration whereas the PV of controls remained stable throughout the study (Table 2).

DISCUSSION

The main finding of this study was that impairment of STM and mood state occurred in collegiate wrestlers when “cutting” body weight at least 5%. RWL also induced a hypoglycemic state that accompanied significant hypoglycemic symptomology.

The effect of RWL on cognition may be related to a host of factors wrestlers endure with this process. Changes in exercise behavior, reduction in blood volume, sleep disturbance, or hypoglycemia could each help to explain the present results. It is well documented that cognitive impairment can accompany a transient drop in blood glucose(5,14,27). Thus, it is reasonable to speculate that a hypoglycemic mechanism contributed to the changes observed in the wrestlers. Although they were only mildly hypoglycemic (glucose:[horizontal bar over]x = 71.1 mg·dL-1), DeFeo et al.(7) have demonstrated cognitive impairments in normal men with similar blood glucose levels.

RWL did not affect performance on tasks demanding attention, visual acuity, or visuomotor skills. Each of these subtests of the cognitive battery required a timed effort, thereby stimulating the wrestlers to overcome the negative influences of RWL. Others have suggested that highly motivated subjects can remain resistant to decrements in cognitive performance despite hypoglycemia-promoting nutritive states(5,8,20).

According to the results of the POMS-R, wrestlers displayed a more negative mood state after RWL than controls. The impact was robust with five of six items (i.e., tension-anxiety, depression-despair, anger-hostility, fatigue-inertia, and confusion-bewilderment) demonstrating greater negativity after RWL. This is not surprising, and reports of transient depression with food deprivation date back to the classic work of Keys et al.(15). To our knowledge, however, this is the first report of an adverse mood effect observed in athletes practicing RWL.

Because RWL preceded an intercollegiate match, it could be argued that impending competition was responsible for the mood negativity seen in wrestlers. Taylor et al. (24) speculated that an approaching meet may have been responsible for a negative mood shift observed in swimmers. However, it is doubtful the present results are associated with precompetition anxiety or aggressive preparatory behaviors because weigh-in(and RWL data collection) always preceded competition by at least 18 hr. Although no measures were made, the wrestlers seemed in much better spirits 2 hr post RWL data collection (i.e., after they had eaten) despite the fact that their match was still pending. Nevertheless, because the isolated effects of upcoming competition on psychological and cognitive function were not examined in the present investigation, it is unclear what influence this may have had on the results. A future study should be designed to separate the influences of RWL and competition on psychological and cognitive function in athletes.

Measures at 72 hr after RWL clearly demonstrated that all observed effects were reversible. With adequate food and fluid intake, body weight, PV, and blood glucose were restored to baseline values. Similarly, the significant decrease in STM, increase in hypoglycemic profile, and shift toward mood negativity were temporary. The simultaneous reversal of cognitive and physiological effects (i.e., blood glucose, PV, body weight) further associates RWL with the observed impairments but still does not rule out the possibility that these results may be partly a result of precompetition effects.

Collegiate and secondary school athletes must also function as students, making the impact of RWL a topic of primary interest to the academic community. From the results of this study, it is difficult to project whether RWL could affect long-term memory (LTM) or whether mood negativity might have acute social or behavioral ramifications. The neurological mechanisms associated with LTM may be very different than those purportedly involved with STM (3,19); however, one theory suggests that new information must first enter STM before storage into LTM(23). The observed effects of RWL in the present investigation will hopefully provoke further study of the potential impact of RWL on LTM, learning, and student-athlete behavior.

In summary, the physiological changes with RWL are well documented in previous research; however, this is the first study to report a transient effect of RWL on both STM and mood state. It appears that the functional impairments accompanying RWL are reversible; however, we can only speculate that there are no long-term implications of this practice. In light of the fact that Horswill (12) has reported no performance advantage for wrestlers who weight cut, one is forced to wonder why this practice persists in this sport. In conclusion, RWL appears to offer no documented reward or advantage, leaving only the potential disadvantages to be carefully considered by both coaches and student-athletes.

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Keywords:

DEHYDRATION; WEIGHT CUTTING; HYPOGLYCEMIA; MEMORY; MOOD

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