Effects of Chromium Picolinate on Beginning Weight Training Students

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1 International lournal of Sport Nutrition, 1992, 2, Effects of Chromium Picolinate on Beginning Weight Training Students Deborah L. Hasten, E. Paul Rome, B. Don Franks, and Maren Hegsted Changes in body weight (BW), a sum of three body circumferences (ZC), a sum of three skinfolds (ZSF), and the one-repetition maximum (IRM) for the squat (SQ) and bench press (BP) were examined in 59 college-age students (37 males [MI, 22 females [F]) over a 12-week weight lifting program. Using a double-blind protocol, half of the students were given 200 pg/day chromium (Cr) in the form of chromium picolinate (CrPic) while the other half received a placebo (P). Therefore four groups were randomly formed: F-CrPic (n=12), F-P (n=10), M-CrPic (n=18), and M-P (n=19). All groups had significant increases in ZC and significant decreases in CSF. No treatment effects were seen for the strength measurements, although the males experienced greater absolute increases. The only significant treatment effect found was due to the F-CrPic group gaining more than the other three groups. It was concluded that CrPic supplementation had a greater effect on the females than on the males. Chromium (Cr) is an essential trace element that is found in the diet. The recommended safe and adequate intake for Cr has been set at pg/day (17). However, approximately 90% of the population may be consuming less than the recommended minimum daily intake of 50 pg (2). Furthermore, absorption of dietary Cr is only 0.5 to 2.0% (17), diets high in refined foods and simple sugars may be deficient in Cr (15,21), and urinary losses of Cr may be increased in response to strenuous exercise (1,3). Therefore Cr deficiencies may be common, particularly among athletes. Various chelating agents may increase or decrease Cr availability (4). When transition metal ions such as copper, iron, and zinc are complexed with picolinic acid, a pyridine-2-carboxylic acid metabolite of tryptophan, their bioavailability may be increased severalfold (7). Chromium also forms stable complexes with picolinate, yielding a compound that consists of one Cr atom surrounded by three molecules of picolinic acid (6). Thus, Cr in the form of chromium picolinate Hasten, Rome, and Franks are with the Dept. of Kinesiology, 112 Long Fieldhouse, Louisiana State University, Baton Rouge, LA Hegsted is with the Dept. of Nutrition, 139 Ecology Bldg., LSU.

2 344 / Hasten, Rome, Franks, and Hegsted (CrPic) may have an increased bioavailability as compared to other forms of dietary Cr. Chromium picolinate has been shown to have beneficial effects upon both blood lipid and glucose levels (5, 19), and it has been implicated in athletic performance as well (5). All of these effects have been attributed to its interaction with the hormone insulin (5). Insulin has been shown to increase glucose and amino acid uptake into muscle cells (12), activate ribosomal translational activity (12), and play a permissive role in growth hormone action through the generation of somatomedin by the liver (10). Additionally, insulin inhibits enzymes that catabolize amino acids and protein (8). Together these factors may cause increased anabolic and decreased catabolic processes in the muscle cell. Furthermore, a decreased dietary-induced thermogenesis seen in obesity may be related to insulin resistance and a decreased rate of glucose storage (9, 20). If such is the case, then the potentiation of insulin by CrPic may help to reduce body fat levels. It has been suggested that if athletes are given Cr in a bioavailable form, they may experience an increase in strength and/or muscle mass with a concurrent reduction in body fat in excess of that due to training alone (5,7). Two preliminary weight training studies presented in an article by Evans (5) reported a significant increase in lean body mass for male subjects taking CrPic as opposed to a placebo group, and one of the studies reported a significant decrease in percent body fat as well. Although Evans (5) did report increases in lean body mass, possible strength changes were not assessed. In sports in which successful performance depends on maximum generation of force, information on the effects of CrPic supplementation on strength changes would be more important than the effects on lean body mass. Therefore the current study was a preliminary investigation designed to assess both body composition and strength effects of CrPic supplementation on beginning weight training students, female and male, over a 12-week period. Subjects Methods Seventy-two apparently healthy students who were enrolled in a beginning weight training class at Louisiana State University volunteered to participate in this study. Fifty-nine (37 males [MI, 22 females [F]) students completed the entire 12-week program. The subjects ranged from 18 to 36 years of age (mean age 21.5 yrs). None had participated in any type of weight lifting for at least 2 years prior to the study. Additionally, none of them were involved in any type of regular physical conditioning outside of class during the study. Each student was randomly assigned to either the CrPic or the placebo (P) groups. Therefore four groups were formed: F-CrPic (n=12), F-P (n=10), M-CrPic (n=18), and M-P (n=19). Procedures A double-blind protocol was used. After random assignment to either the CrPic or the P treatment, each student was given a vial with the corresponding capsules and instructed to take one every morning. The capsules contained either 200 pg of Cr in the form of CrPic or an inert lactose compound. Compliance was

3 Effects of Chromium Picolinate / 345 monitored by a capsule count every 3 weeks. The subjects were requested not to alter their dietary habits during the course of the study. Five testing sessions (pre, Weeks 3,6, and 9, post) were administered over the 12 weeks. The measurements taken at each session included BW, three body circumferences, three skinfold measurements, and the one-repetition maximum (1RM) for both the squat (SQ) and the bench press (BP). Body weight was measured to the nearest 1/10 kilogram (kg), and circumferences were measured to the nearest 1/10 centimeter (cm). One person performed all BW and circumference measurements for all testing sessions. For the BW measures each student wore only a T-shirt, shorts, and tennis shoes. For the circumferences a tape measure was firmly applied without compressing the skin. A chest circumference was taken at the nipple level for the men and just below the breastline for the women. An arm circumference was taken midway between the shoulder and elbow joints, and a thigh circumference was measured midway between the greater trochanter and knee joint. These three circumferences were chosen because they were most representative of the muscle groups directly stressed in the program. The three circumference measurements were then added together to obtain a sum-of-circumference index (ZC). For the skinfold measurements, one experienced tester performed all measurements at all testing sessions. The skinfolds measured for the women included the sites of the triceps, suprailiac, and thigh, whereas those for the men were the pectoral, abdominal, and thigh measures. The sites were identified and measured as described by Sinning et al. (22). Three independent measures were taken at each site with Lange calipers, and the average values of the three measurements were then added to obtain a sum-of-skinfolds index (CSF). After a warm-up set of 15 repetitions with a light weight, each student progressively added weight to the bar until the 1RM was met for both the SQ and BP. For the SQ, a position at which the upper thigh was parallel to the ground was required for the lift to be counted. Additionally, no bouncing was allowed at the bottom of the movement. For the BP, a full range of movement was required in which the bar touched the chest, but again no bouncing was allowed. Although spotting was required, any body contact of the spotter with the lifter or the weight disqualified the attempt. A11 subjects worked out on a 3-daylweek weight training program for approximately 40 minutes/session. Exercises included the basic movements of the BP, SQ, military press, and bent-over row, as well as auxiliary movements such as dumbbell flyes for chest and shoulders, lat pull-downs, and arm curls and extensions. All subjects performed the same exercises and were instructed to choose a weight load for each set so that the repetitions were in the 6-10 range with the last repetition at near maximum effort. Therefore all subjects worked at similar relative intensities, and a progressive overload was accomplished as each subject increased in strength over the 12-week period. Participation was high and none of the subjects missed more than two training sessions. Additionally, the capsule count indicated that none of the subjects missed more than two capsules over the entire study period. Statistical Analyses A 2 x 2 x 5 factorial ANOVA for treatment (tmt), gender (sex), and time, with repeated measures over time, was used to analyze the data. The variables examined included BW, CC, CSF, and the 1RM for the SQ and BP. Although the values presented in the tables give only pre- and posttest measurements with differences

4 346 / Hasten, Rome, Franks, and Hegsted for descriptive purposes, statistical analyses took all five testing sessions into consideration. A polynomial contrast across time was fitted for each treatment effect that was found to be significant. Due to the large number of variables examined, the error rate was consequently inflated. Therefore the level of significance was set at the p<0.01 level. Results Group pre- and posttest means and differences for BW, CC, and CSF measurements are presented in Table 1. The TmtxSexxTime interaction was significant for Over the 12-week period, the F-CrPic group gained significantly more weight (2.5 kg) than the other three groups (from 0.6 to 1.3 kg). Due to the large gender related differences in BW, the BW measurements that were taken at each testing session were also expressed as a percentage of pretest values, giving a relative BW value. The TmtxSexxTime interaction was also significant for BW in relative The F-CrPic group experienced a 4.3% increase in BW whereas the increase for the other groups was only 0.9 to 2.0%. A plot of relative BW over the 12-week period for all four groups can be seen in Figure 1. For the CC, only was significant. The mean increase in CC across all subjects was 2.3 cm over the 12 weeks. Time was significant for CSF across all although no significant differences were found between groups. The change in CSF during the 12 weeks was -4.8 mm for the females and -3.3 mm for the males. The pre- and posttest group means and differences for the SQ and BP are given in Table 2. The SexxTime interaction was significant for both the ) and the The males increased in strength to a greater Table 1 Pre- and Posttest Group Means and Differences for Body Weight, Circumference, and Skinfold Measurements Bw (kg) ZC (cm) CSF (mm) Group Pre Post Diff. Pre Post Diff. Pre Post Diff. F-CrPic (6.1) (7.0) F-P (6.6) (6.8) M-CrPic (8.3) (7.9) M-P (13.2) (13.0) See text for abbreviations. Standard deviations in parentheses. Note. Time was significant for CC and ZSF across all subjects, p = **Significantly different from the other groups, p =

5 Effects of Chromium Picolinate I 347 -e - F-CrPic " -O- M-P 2.0%..*-. M-Crpi~ -0- F-p 1.2% TIME (Weeks) Figure 1 - Relative body weight gains over 12 weeks. Standard deviation values are represented by error bars. **Significantly different from the other groups,p< Table 2 Pre- and Posttest Group Means and Differences for Strength Measurements SQ (kg) BP (kg) Group Pre Post Diff. Pre Post Diff. F-CrPic 45.2 (16.1) F-P 46.0 (9.2) M-CrPic 94.4 (24.3) M-P 89.4 (26.7) See text for abbreviations. Standard deviations in parentheses. **Significantly different from the other groups, p = for SQ and p = for BP. extent than the females in both the SQ (41.3 kg vs kg) and the BP (11.9 kg vs kg) over the 12 weeks. Since the TmtxSexxTime interaction for BW was the only significant treatment effect at the chosen level of significance, a polynomial contrast was only performed for this variable. The 1st-degree polynomial contrast was found to be the most significant (p=0.0287). Discussion The only treatment effect or interaction that was found to be significant at the p= 0.01 level was the TmtxSexxTime interaction for BW, expressed both in absolute

6 348 / Hasten, Rome, Franks, and Hegsted terms and as a percentage of initial pretest values. This was due to the F-CrPic group gaining significantly more weight over the 12-week period than the other three groups. Although the chosen level of significance was not quite reached, the TmtxTime interaction for CC approached significance (p=0.0344), indicating that both the male and female CrPic groups increased to a greater extent than did the female and male P groups. Perhaps the CrPic was responsible for a slight increase in girth at these sites, but these did not show up in the BW measurements for the M-CrPic group as they did for the F-CrPic group. However, it should be noted that while the M-CrPic group showed a gain in I;C that was twice that of the M- P group, it only amounted to a difference of 1.8 cm. Considering that this was a sum of the chest, arm, and thigh, the actual relevance of this difference is questionable, particularly since there were no other significant differences between the two groups. The 3.0-cm overall increase for the F-CrPic group with no measurable increase for the F-P group further supported the differences found between these two groups in terms of BW gains. Only time was a significant factor in decreases seen in XSF. Therefore CrPic did not appear to increase body fat losses beyond those due to the exercise regimen itself. When the skinfolds were used in body density regression equations (13, 14) in order to approximate the changes in percent body fat (%BF) and lean body mass (LBM), no differences were found between groups. However, the SexxTmtxTime interaction (p=0.0459) approached significance for relative gains in estimated LBM (when each test value was expressed as a percentage of the pretest value). In terms of relative gains, the F-CrPic group experienced an increase in estimated LBM of 6.2% over the 12 weeks whereas the other groups appeared to gain only between 2.3 and 3.3%. This may indicate that most of the additional BW gains of the CrPic group were due to increases in LBM. Since the F-CrPic group appeared to gain nearly twice as much LBM as the F-P group, these differences were probably minimized somewhat in the overall analyses that included both sexes. The males increased in strength to a greater extent than the females for both the SQ and BP. The sex related differences in these values were probably due to the considerably heavier weights lifted by the males, and therefore a greater absolute increase in strength was noted. However, since no treatment effects were seen, the CrPic did not facilitate strength increases beyond those due to training alone. These trends suggest that the major increase in BW for the F-CrPic group was due to an increase in LBM. In fact, all groups appeared to gain more LBM than BW due to concurrent decreases in CSF and estimated %BF. However, only the F-CrPic group differed significantly from the others in terms of treatment effects. Furthermore, the polynomial contrast for time indicates that the increase in BW for the F-CrPic group was largely a linear increase across the entire 12- week period. The results of this study indicate that although the CrPic may have been effective in increasing overall BW with nonsignificant trends for increases in relative LBM for the F-CrPic group, the treatment was not effective in reducing CSF beyond that due to training factors alone. However, the trend toward increased LBM, if confirmed in future studies, could have long-term effects on body fat reductions since LBM is the primary determinant of the basal metabolic rate (16).

7 Effects of Chromium Picolinate / 349 Although the CrPic supplementation appeared to be beneficial to the females in the study as far as BW gain is concerned, such was not the case for the male subjects. Perhaps the females were consuming a diet that was more deficient in Cr than the males. In such a case the supplement would only be expected to be beneficial in Cr deficiency. However, if this were the case, both of the male groups should have made BW gains similar to those of the F-CrPic group. Alternatively, a dose-dependent relationship could be in effect. Since the males outweighed the females by an average of 11.0 kg with a mean difference in estimated LBM of 18.3 kg, perhaps they needed a greater dosage for the full effects to be seen. The differences seen between the sexes could also have been due to differences in insulin production and/or resistance. For a given glucose load, it has been shown that females produce significantly more insulin than males, with the greatest difference seen in the 16- to 29-year age group. Additionally, females of all ages appear to have less insulin resistance than males (18). This increased production and "activity" of insulin seen in females could help to account for the fact that they responded to the CrPic supplementation significantly whereas the males did not. Another possibility is that the males were relatively more trained at the beginning of the study. Although none of the subjects had been involved in any type of weight training for at least 2 years, it is possible that other forms of activity could have produced some degree of muscle hypertrophy prior to the study. However, this could only explain differences between the sexes, not differences found between the F-CrPic and F-P groups. The results of this study do not agree entirely with previous studies. Unlike the present study, both of the studies reported by Evans (5) involved only male subjects. One study, which reported significant increases in BW, LBM, and calf circumference, correlated most closely with this study, but our results were significant for the females rather than the males. Perhaps the rather large gains seen by all students in this study masked any effects that might have been seen if the students had been more experienced in weight-lifting. This may also explain why the decreases in ZSF between CrPic and P groups were not significant, as was found for the football players in the other study reported by Evans (5). Similar effects could have occurred for the strength measures of the SQ and BP, in which beginners are always expected to show large improvements during the first few weeks. Chromium picolinate may exert more dramatic effects upon those who have been training for longer periods of time, since most beginning subjects usually experience quite dramatic initial results regardless of outside factors. Such has been the finding in many studies involving the use of anabolic steroids (1 1). In conclusion, CrPic, in the dosage of 200 pglday, was shown to be beneficial in terms of weight gain for beginning female weight-lifting students but not for their male counterparts. In future studies the Cr status of the subjects, both before and after the study, should be examined. Also, further work should be done to determine whether these results are due to sex related differences, or whether males, with a significantly greater initial LBM, may benefit by taking a greater dosage.

8 350 / Hasten, Rome, Franks, and Hegsted References 1. Anderson, R.A., N.A. Bryden, M.M. Polansky, and P.A. Deuster. Exercise effects on chromium excretion of trained and untrained men consuming a constant diet. J. Appl. Physiol. 64: , Anderson, R.A., and A.S. Kozlovsky. Chromium intake, absorption and excretion of subjects consuming self-selected diets. Am. J. Clin. Nutr. 41: , Campbell, W.W., and R.A. Anderson, Effects of aerobic exercise and training on the trace minerals chromium, zinc and copper. Sports Med , Chen, N.S.C., A. Tsai, and I.A. Dyer. Effect of chelating agents on chromium absorption in rats. J. Nutr. 103: , Evans, G.W. The effect of chromium picolinate on insulin controlled parameters in humans. Int. J. Bios. Med. Res. 11: , Evans, G.W. The Picolinates. New Cannan, CT: Keats Publ. Co., Evans, G.W. The role of picolinic acid in metal metabolism. Life Chem. Rep. 1:57-67, Felig, P. Amino acid metabolism in man. Ann. Rev. Biochem , Felig, P. Insulin is the mediator of feeding-related thermogenesis: Insulin resistance and/or deficiency results in a thermogenic defect which contributes to the pathogenesis of obesity. Clin. Physiol. 4: , Golde, D.W., N. Bersch, S.A. Kaplan, D.L. Rimoin, and C.H. Li. Peripheral unresponsiveness to human growth hormone in Laron dwarfism. N. Eng. J. Med. 303: , Haupt, H.A., and G.D. Rovere. Anabolic steroids: A review of the literature. Am. J. Sports Med. 12: , Hill, D.J., and R.D. Milner. Insulin as a growth factor. Ped. Res. 19: , Jackson, AS., and M.L. Pollock. Generalized equations for predicting body density of men. Br. J. Nutr. 40: , Jackson, AS., M.L. Pollock, and A. Ward. Generalized equations for predicting body density of women. Med. Sci. Sports Exerc. 12: , Kozlovsky, A.S., P.B. Moser, S. Reiser, and R.A. Anderson. Effects of diets high in simple sugars on urinary chromium losses. Metabolism , Lohman, T.G. Skinfolds and body density and their relation to body fatness: A review. Human Biology 53: , National Research Council. Recommended Dietary Allowances (10th ed.). Washington, DC: National Academy Press, Orchard, T.J., D.J. Becker, L.H. Kuller, D.K. Wagener, R.E. LaPorte, and A.L. Drash. Age and sex variations in glucose tolerance and insulin responses: Parallels with cardiovascular risk. J. Chron. Dis , Press, R.I., J. Geller, and G.W. Evans. The effect of chromium picolinate on serum glucose and apolipoprotein fractions in human subjects. West. J. Med. 152:41-45, Ravussin, E., K.J. Acheson, 0. Vemet, E. Danforth, and E. JCquier. Evidence that insulin resistance is responsible for the decreased thermic effect of glucose in human obesity. J. Clin. Invest. 76: , Schroeder, H.A. Losses of vitamins and trace minerals resulting from processing and preservation of foods. Am. J. Clin. Nutr. 24: , Sinning, W.E., D.G. Dolny, K.D. Little, L.N. Cunningham, A. Racaniello, S.F. Siconolfi, and J.L. Sholes. Validity of "generalized" equations for body composition analysis in male athletes. Med. Sci. Sports Exerc. 17: , 1985.

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