Physiology and Biochemistry
103
Acute Hormonal Responses in Elite Junior Weightlifters W. J. Kraemert , A. C. Fryt, B. .J. Warren2, M. H. Stone2, S. J. Fleck3, J. T. Kearney3, B. P. Conroy4, C. M Maresh4, C. A. Weseman4, N. T Triplett', S. E. Gordon1 'Center for Sports Medicine, The Pennsylvania State University, University Park, PA, 16802 USA -Department of Health, Leisure and Exercise Science, Appalachian State University, Boone, NC, 28608 USA 3Sports Science Division, U. S. Olympic Committee, Colorado Springs, CO, 80909 USA 4Human Performance Laboratory, Department of Sport, Leisure, and Exercise Sciences, The University of Connecticut, Storrs, CT, 06268 USA
W. J. Kraerner, A. C. Fry, B. J. Warren, M. H.
Stone, S. J. Fleck, J. T. Kearney, B. P. Conroy, C. M Maresh, C. A. Weseman, N. T. Triplelt and S. E. Gordon, Acute Hormonal Responses in Elite Junior Weightlifters. IntJSportsMed,Vo113,No20,pp103—lO9,l992. Accepted after revision: June 10, 1991
To date, no published studies have demonstrated resistance exercise-induced increases in serum testosterone in adolescent males. Furthermore, few data are available on the effects of training experience and lifting performance on acute hormonal responses to weightlifting in young males. Twenty-eight junior elite male Olympic-
style weightlifters (17.3±1.4 yrs) volunteered for the study. An acute weightlifting exercise protocol using moderate to high intensity loads and low volume, characteristic of many weightlifting training sessions, was examined. The
plasma fI-endorphin, and whole blood lactate. The exercise protocol elicited significant (p 0.05) increases in each of the hormones and whole blood lactate compared to pre-exercise measures. While not being significantly older, subsequent analysis revealed that subjects with > 2 years train-
ing experience exhibited significant exercise-induced increases in serum testosterone from pre-exercise to 5 mm
post-exercise (16.2±6.2 to 21.4±7.9 nmolll, while those with 2 years training showed no significant serum testosterone differences. None of the other hormones or whole blood lactate appear to be influenced by training experience. Exclusive from years of training, strength levels did not influence hormonal response patterns as lifters classified as strong showed no differential responses from those classified as weak as both groups demonstrated hormonal increases with acute exercise. These data suggest that training experience in elite adolescent weightlifters is most
influential when examining the hypopituitary-gonadal training adaptations.
exercise protocol was directed toward the training associated with the snatch lift weightlifting exercise. Blood samples were obtained from a superficial arm vein at 7 a. m. (for baseline measurements), and again at pre-exercise, 5 mm post-, and 15 mm post-exercise time points for determination of serum testosterone, cortisol, growth hormone,
Introduction
Chronic resistance training may alter the mechanisms involved with cybernetic control of acute neu-
roendocrine responses and exercise adaptations (7, 14). Häkkinen and co-workers (7) have demonstrated increased baseline testosterone levels in elite adult male weightlifters over the course of two years of resistance training. Conversely, shorter training periods (one year or less) have shown no base-
line changes in serum testosterone concentrations (6, 9, 10, 18). Acute increases in serum concentrations of cortisol (5, 8), testosterone (5, 13, 23), growth hormone (13, 14, 15, 18, 22), and plasma 3-endorphin (2) have been observed consequent to various resistance exercise protocols in adult males.
Key words
Testosterone, cortisol, growth hormone, endorphin, blood lactate, resistance exercise, strength, an-
aerobic
The acute hormonal responses of adolescent individuals to heavy resistance exercise is less understood. Fahey et al. (3) observed no increases in serum testosterone concentrations immediately following a heavy resistance exercise session in high school males (16.0 0.8 yrs). In contrast, they did observe increases in serum testosterone in both ex-
perienced and inexperienced college-aged males after a resistance exercise session. Lukaszewska et al. (14) have shown increases in growth hormone and cortisol in adolescent males after a weightlifting session. Such limited data indicate that for the hormone testosterone, younger males are unable to stimulate exercise-induced increases in serum concentrations with resistance exercise. Still, with such limited data on hormonal
responses to heavy resistance exercise in younger men, no definitive pattern of any hormonal response can be readily gleaned from the literature.
lnt.J.SportsMed. 13(1992)103—109 GeorgThieme Verlag StuttgartNew York
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Abstract
104 mt. J. Sports Med. 13(1992)
W. .1. Kraemer, A. C. Fry, B. J Warren, M. H. Stone, S.f. Fleck, I. F Kearney ezal.
Table 1 Subject character istics (n = 28) Variable
17.3± 1.4 167.2± 2.8 67.8 11.9 2.8
pre-exercise (2 p.m—S p.m.)
* 5 mis post
-j
15 mm post
1.5
3.6± 1.0 6.2
L
7am.
exercise
2.2
63.5 10.4 145.1
94.2± 19.2 120.2±23.5 213.0±42.4
Therefore, the primary purpose of this investigation was to determine the effects of an acute weightlifting exercise session on a wide spectrum of hormonal responses in elite adolescent male weightlifters. Additionally, we were also interested in the influence of maximal strength and training experience on the hormonal response patterns. Methods Twenty-eight participants in a junior age group national weightlifting training camp volunteered as subjects for this investigation (X±SD; age=l7.3± 1.4 yrs,
height= 167.2±2.8 cm, body weight=67.8± 11.9 kg).
Prior to the study, each subject was informed of the possible experimental risks and signed an informed consent document (both subject and parent if under the age of 18 yrs). Complete descriptive data is listed in Table 1. Body density was estimated by anthropometric methods using the seven skinfold site equation of Jackson and Pollock (11). Relative fat levels were calculated by the formula of Sin (17), thus permitting the determination of fat free mass. Tanner maturity ratings were estimated from the pre-exercise testosterone concentrations
blood samples # anthropometric measures exercise protocol — 15 vertical jumps snatch lift lest 3 x 10 snatch pulls
Fig. 1 Experimental design timeline.
where one lift is featured in the training session. Warm-up ex-
ercises and heavy lifts are followed by lower intensity, high volume weightlifting exercise for conditioning. The specific exercise protocol used in this investigation consisted of fifteen maximum effort vertical jumps (VJ) performed at a clocktimed cadence of 1 every 3 seconds. During the jumps the lifters' hands were kept on the hips for all the jumps. A countermovement was allowed but no steps were permitted and therefore the leg muscles were utilized in a similar motion as in the
snatch lift. Following the jumps and a 1-minute rest period, each subject performed 10 single warm-up repetitions using the snatch lift with 40% of their best competitive 1 repetition maximum (1 RM) performance. All lifts in this investigation were determined as a percentage of their best competitive snatch lift (1 RM). These warm-up repetitions were not timed, but were generally completed in 2—3 minutes. This was followed by another one-minute rest, after which each subject began the actual snatch lift exercise protocol. Beginning with 50% of 1 RM for the snatch lift, one repetition was performed every 15 seconds (clocked timed, verbal ques), with the load for each successive lift being increased by 5 kg. Lifting continued
junior age group national team.
until each subject missed two consecutive attempts. This was followed by a three-minute rest period, after which three sets of 10 repetitions were performed using the snatch lift high pull exercise with a load of 65% of 1 RM. In order to standardize the efforts, a clock-timed cadence and verbal ques were again given and allowed for one lift to be performed every four seconds. Each set was separated by a one-minute rest period.
Following a 12-hour fast, blood samples were obtained at 7 a. m. to determine baseline values of total testost-
Whole blood was immediately assayed in duplicate for lactate concentrations using a YSI 23L lactate ana-
erone, cortisol, growth hormone, fEl-endorphin, and whole blood lactate. Such data would allow for the examination of diurnal variations of each hormone over the experimental test day for each hormone. Approximately 15 ml of blood was obtained at each time point to assay for the hormones in this study. Blood samples were obtained from an antecubital arm vein by venipuncture using a 21 gauge needle and vacutainer assembly and vacutainer collection tubes. Serum vacutainers contained no preservatives and the plasma vacutainer con-
lyzer (Yellow Springs Inc., Yellow Springs OH). Blood samples were centrifuged for 15 mm at 1500 >< g (4 °C for plasma and room temperature for serum) processed and
(4), with all testosterone concentrations falling within the ranges expected for the subjects' respective ages (16). All athletes were selected for the training camp based on previous
drug tested competitive performances, for which none had tested positive. Included in the group were members of the
tained EDTA [7.2 mg-S mF 1of whole blood]. The subjects reported for the actual exercise test session between 2—5 p. m. (see Fig. 1). Pre-exercise blood samples were taken prior to exercise and again at 5 and 15 minutes following the exercise session.
serum and plasma was stored at —90 °C until assayed. Plasma and serum samples were thawed only once before analyses. Radioimmunoassays for each hormone were performed in duplicate and sample identification was decoded only after analyses were completed (i. e., blinded analysis procedure). Tmmunoreactivity values were determined with a gamma counter (Searle 1195, Analytic Series Inc.) and a Beckman 5500 data reduction frocessor. Plasma J3-endorphin was determined
using an i radioimmunoassay (IncStar, Stillwater, MN), which has been previously described in detail (12). With the
preliminary extraction procedures utilized in this assay, crossreactivity with fEl-lipotropin was less than 5%. The intraThe exercise session was designed to simulate a
assay coefficient of variation was 8.1 % and the inter-assay
typical progression during a weightlifting training session
coefficient of variation was 12.0 %. Serum human growth hor-
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Age (yrs) Height (cm) Body weight (kg) Years Trained Estimated Tanner Maturity Rating Relative Fat (%) Fat Free Mass (kg) 3 RM Squat (kg) 1 RM Snatch (kg) 1 RM Clean and Jerk (kg) Total [snatch + clean and jerkl (kg)
*
Intl SportsMed. 13 (1992) 105
Acute HormonalResponses in Elite Junior Weightlflers
Fig. 2 Mean (± SD) hormonal and lactate response patterns of highly experienced (> 2 yrs training; n = 16) and less experienced ( 2 yrs training; n = 12) junior age group Olympic weightlifters are presented. ......U nderlined bar values represent no significant (p > 0.05) differences between combined group data across various time points (main effect). = p < 0.05 between groups A 7 a. m. > pre-ex, 5 mm, and 15 mm for 2 yrs experience group B = 7 a. m. > pre-ex, and 15 mm for >2 yrs experience group C = 5 mm > pre-ex value for > 2 yrs experience group
0 E
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C
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00
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0.175
2years
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>2years
0.150
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0.075
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mone was determined in duplicate using a liquid phase, double anti-body radioimmunoassay technique (ICN Biomedicals, Inc., Carson, CA). Serum cortisol and testosterone
were analyzed in duplicate using a solid phase radioimmunoassay technique (ICN Biomedicals, Inc., Carson, CA). For serum growth hormone, testosterone, and cortisol the intra-assay variances were less than 3.0% and the inter-assay variances were less than 5.8 Va. Testosterone to cortisol ratios were determined to examine the changes in the theoretical anabolic to catabolic changes during the day and in response to the weightlifting exercise session (9). Plasma volume shifts for this exercise protocol were calculated to be less than 10°/I and did not effect the response patterns of this study (1). Serum
hormone concentrations were not corrected for plasma
5 mm
15 mm
tion of the investigation. Neither subjects nor the investigators knew subject classifications during the study. In order to determine the possible effects of strength levels on the acute hormonal responses to the exercise session, subjects were divided
into strong (n 11) and weak (n= 17) groups. This was accomplished by using a classification system developed by the
U. S. Weightlifting Federation (21) that corrects for their weight class, thus allowing subjects to be categorized as master
or class I lifters (strong) and class IT or III lifters (weak). A balanced design existed for the number of subjects in each of four cells created by this dual classification of training level and strength level.
A two-way analysis of variance (2 x 4)
volume shifts in this investigation.
[group x time] with repeated measures was utilized for statistical treatment of the data. Post-hoc analyses included one-way
To determine the effects of training experience on the acute hormonal responses to the exercise session, the subjects were divided into highly experienced (n== 16; >2 years supervised weightlifting) and less experienced (n 12; 2 years supervised weightlifting) groups after the comple-
(1 x 4) repeated measures analyses of variance and independent Tukey tests. Independent t-tests were used to determine significant differences between the groups (highly experienced vs less experienced; strong vs weak) for all physical performance measures. Pearson product-moment correla-
106 mt. J. Sports Med. 13 (1992)
W. I Kraemer, A. C. Fry, B. J. Warren, M. H. Stone, S. J. Fleck, J. T Kearney et al. Fig. 3 Mean (± SD) hormonal and lactate response patterns of strong and weak
35
30 0 E
C
0 U)
t 0 0
10
groups of junior age group Olympic weightlifters.
..__Underlined barvalues represent no significant (p> 0.05) differences between combined group data across various time points (main effect). D = 7 a. m., and 5 mm > pre-ex for the
strong group E = 7 a. m. > pre-ex, 5 mm, and 15 mm for the weak group
7am, pre-ex
5 mm
15 mm
F = 5 mm > pre-ex for the weak group
0.175
• strong weak
0.150
0) rI.
)0
0 0 0 C 0 0 (0 0 U)
0.125
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0.075 0.050 0.025 0.000
ui.i ii 7am. pre-ex
5 mm
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0
0)
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0
15 mm
0 E
0 E E 0
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P
tions were used to examine bi-variate relationships between blood lactate concentrations and the hormonal responses. Significance in this investigation was chosen as p < 0.05. The data are presented as means 1 standard deviation. Results
When comparing the groups separated by the experience classification, no differences were observed be-
tween experience groups except for the number of years trained. Comparisons of the strong and weak classification groups, as expected, demonstrated that the strong group had superior performances on all the strength-related variables. It should be noted that although the strong group lifted heavier weights during the exercise session, the loads represented a similar percent of 1 RM as that lifted by the weak group. The strong group also performed a significantly greater number of attempted snatch lifts, due primarily to the greater absolute loads lifted. This is explained by the absolute increments of loading utilized in the exercise test session (i. e., 5 kg) that resulted in a lower relative % increase for the strong group based
on maximum weight lifted during the snatch test (i. e., = 5.1 % increment for the strong group and 6.7% increment for the weak group). The strong group was also significantly older than the weak group, but was apparently not more mature as indicated by pre-exercise testosterone levels (4). These group comparisons are shown in Table 2.
Comparisons of training experience ( 2 yrs
vs > 2 yrs) on the hormonal response patterns and blood lactate are illustrated in Fig. 2. Only one significant difference between groups was revealed at any one time point for any of the
variables observed (i. e., TES/CORT at 7 a. rn). However, changes across time were evident for each variable when both groups were combined (i. e., main effect). These are indicated by the underlined bars in Fig. 2, and indicate significantly dif-
ferent hormonal and lactate concentrations. As expected, 7
a. m. baseline values for testosterone were significantly greater than all other sample time values. Furthermore, significant increases from pre-exercise to 5 minutes post-exercise were observed for all of the hormones and whole blood lactate.
Both serum testosterone and serum growth hormone main-
Jut. J. Sports Med. 13(1992) 107
Acute HormonaiResponses in Elite Junior Weigh t4fters
exercise. On the other hand, plasma -endorphin and whole blood lactate significantly decreased from 5 minutes to 15 minutes post-exercise. Although both serum testosterone and cortisol increased due to exercise, the cortisol response was greater. This resulted in a significant decrease in testosterone/cortisol ratio (TES/CORT) from 7 a. m. values to 15 minutes post-exercise values. However, no significant differences were observed from pre-exercise to 1 5 minutes post-exercise.
Significant interaction effects occurred for both serum testosterone and the TES/CORT ratio. For testosterone, the less experienced group ( 2 yrs) exhibited a significant decrease from 7 a. m. to pre-exercise, after which
serum testosterone values did not change. The more experienced group (>2 yrs) also demonstrated a significant decrease from 7 a. m. to pre-exercise but then exhibited a significant increase in serum testosterone concentrations from
pre-exercise to 5 minutes post-exercise, after which testosterone values returned to pre-exercise levels by 15 minutes
Discussion
The most remarkable finding in this investigation was that the length of resistance training experience appears to influence the exercise-induced response patterns of testosterone in adolescent males. An exercise-induced increase in serum testosterone was observed consequent to the weightlifting exercise session only in the group of elite junior weightlifters with more than 2 years of training experience. This finding is even more striking because we also demonstrated that despite a high level of performance ability and training background, the group of weightlifters with less than 2 years' training experience did not exhibit a significant exercise-induced increase in serum testosterone concentrations. The later finding is consistent with data from Fahey and coworkers (3), who did not observe any increases in serum testosterone following a heavy resistance exercise protocol (i. e., 3 sets of 5 repetition maximum loads for the bench press, seated press, and the leg press) in high-school-aged males.
Chronic exposure to resistance exercise (i. e., long-term training) may play a crucial role in stimulating an ac-
tivation of the hypopituitary-gonadal axis to resistance exercise. The mechanisms which mediate such changes remain unThe TES/CORT analysis also exhibited a sig- clear but could be related to changes in the cybernetic feednificant interaction effect due to a significant difference in the back mechanisms in the hypopituitary-gonadal axis and/or a remodelling of the testicle cell structures to promote increased 7 a. m. values, with the less experienced group having a higher ratio. All other TES/CORT responses were similar for both release (4, 19). In adult weightlifters, observations over two years by Häkkinen and co-workers (7) support this hypothesis experience groups. that chronic intense strength training is necessary to observe The responses of hormonal and blood lactate resting baseline changes in serum testosterone responses. Our data demonstrated no differences in resting baseline levels of between strength classification groups (strong vs weak) are serum testosterone between the two groups. This suggests that shown in Fig. 3. Significant changes across time were evident when both groups were combined for each variable (i. e., main the adaptational response in younger weightlifters may be more related to the neuroendocrine activation mechanisms in effect). These are indicated by underlined bars in Fig. 3. As the hypopituitary-gonadal axis, which could cause exercisepreviously observed, testosterone values at 7 a. m. were signifiinduced increases in testosterone. Alternatively, it is possible cantly greater than all other sample time values. Again, significant increases were observed for all hormonal and blood lac- that other physiological mechanisms in the body could contribute to concentrating peripheral blood levels during and tate responses from pre-exercise to 5 minutes post-exercise. As after exercise. While plasma volume shifts are a factor, other with the previous analyses, testosterone and growth hormone maintained their elevated levels at 15 minutes post-exercise, concentrating mechanisms which would regulate peripheral while cortisol continued to increase from 5 to 15 minutes post- blood concentrations might also become differentially operin more experienced lifters. It might be speculated that exercise. Again, 3-endorphin and blood lactate significantly ational decreased degradation, changes in clearance rates from tissues decreased from 5 minutes to 15 minutes post-exercise. As previously observed, TES/CORT decreased from 7 a. m. to 15 (hepatic and extra-hepatic), changes in protein transport and binding, and differential cell receptor alterations (e. g., recepminutes post-exercise. tor number and binding affinity) could all theoretically proWhen comparing strength levels, a significant duce differential responses between experienced and inexinteraction effect was observed for serum testosterone. Both perienced lifters due to training adaptations at the molecular postexercise.
the strong and the weak groups exhibited a significant decrease in testosterone from 7 a. m. to pre-exercise, as well as a significant increase from pre-exercise to 5 minutes post-exercise. However, testosterone levels for only the strong group returned to 7 a. m. concentrations by 5 minutes post-exercise.
Simple regression analysis demonstrated no systematic bi-variate relationships between blood lactate and the hormonal responses in this investigation. The only significant correlations were between whole blood lactate following exercise and 3-endorphin [5 mm post] (r = 0.31), and 1-endorphin [15 mm post] (r= 0.53) accounting for less than 29% of
the shared variance between the two variables. No other significant correlations were observed.
level.
The differences observed in this investigation attributed to length of the training experience appear to be solely related to the serum testosterone responses. This is sup-
ported by the fact that both the experienced and less experienced groups demonstrate significant exercise-induced increases in all of the other hormonal variables consequent to the weightlifting exercise session. Neither serum growth hormone and cortisol nor plasma 3-endorphin showed any differences due to training experience or strength classifications. In adult males, serum growth hormone concentrations have been shown to significantly increase in response to heavy resistance exercise stress (13, 20). The magnitude of the growth hormone
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tamed their increased levels at 15 minutes post-exercise, while serum cortisol continued to increase from 5 to 15 minutes post-
mt. J. Sports Med. 13(1992)
W. J. Kraemer, A. C. Fry, B. .1 Warren, M H. Stone, S. J. Fleck, J. T Kecirney et al.
Table 2 Comparisons of Group Characteristics (X SD) Variable
Highly Experienced
Less Experienced
(n=16)
(n=12)
17.3± 1.9 17.4±1.1 Age (yrs) 170.7± 8.1 170.7±6.4 Height (cm) 67.8± 14.7 67.8±9.9 Body Weight (kg) Relative Fat (%) 6.1 6.4± 2.4 Fat Free Mass (kg) 63.6 8.6 63.3 12.9 3.8±1.1 1.5± 0.6** Years Training Estimated Tanner 3.6±1.1 3.6± 1.0 Classification 1.5±0.6 1.8± 0.9 (1 = Master,2 = Class I, 3 = Class II, 4 = Class Ill)
Strong
Weak
(n=11)
(n=17)
18.6±0.9 172.2±6.7
71.9±9.2 6.4± 1.9
67.3 8.5 3.1
3.8±1.0 1.8±0.4
16.5± 1.0* 1695± 7.3 65.2± 12.9 6.1 61.0
2.5 11.1
2.6± 1.3 3.5± 1.0 3.2± 0,4*
Lifting Capabilities 150.2±26.7
3 RM Squat (kg)
Squat/Body Mass SquatfFFM 1 RMSnatch (kg) Snatch/BM Snatch/FFM Clean and Jerk CJ/BM CJ/LBM
2.21
2.36±0.28 97.5± 17.0
1.37±0.30 1.53±0.41 122.5±21.9 1.81
1.92±0.17 218.6±38.3 3.07±0.54 3.43±0.29
Total (kg) Total/BM Total/FFM
126.3±53.3 1.90±0.67 2.02±0.72 89.9±21.7 1.33±0.22 1.42±0.25 117.1±26.0 1.75±0.20 1.85±0.25 205.5±47.9 3.04±0.42 3.25±0.48
170.2± 17.2
2.38±0.21 2.55±0.24 111.7± 10.8 1.56±0.11
1.67±0.12 139.8± 14.7 1.95±0.10
2.09±0.12 249.6±25.1 3.48±0.21 3.73±0.22
120.3± 40.5*
1.88± 0.53 2.00± 0.57* 82.9±14.2* 1.22± 0,25* 1.36± 0.13* 107.5± 19.0*
1.67± 0.11 * 1.77± 0.14* 189.3±33.4*
2.79± 0.41* 3.11
0.24*
74.9 90.2
13.45*
Results of the 5 kg incremental snatch lift test within the exercise session
Weight Lifted (kg)
85.8 16.3
%1RM
88.1
Number of Attempts Number of Misses
7.6
8.2± 1.9
0.3±0.6
81.9 18.4 91.2 7.7 7.9± 1.9 0.5± 0.8
98.4
11.
88.3 7.0 9.4±1.6 0.3±0.5
8.2
7.2± 1,6* 0.5± 0.8
0.05 from corresponding strong classification 0.05 from corresponding highly experienced classification FFM = fat free mass (kg) BM = body mass (kg) **p
Clean and Jerk (CJ) and Snatch lifts from competitive tests, and 3 RM squat determined during the lifting camp.
response has been observed to be greater when the length of
the rest periods are short (i. e., 1 mm) and/or when large muscle group exercises are utilized (7, 8, 13). In this investiga-
tion the use of shorter rest periods and multi-joint exercises may have contributed to the large increases in serum growth hormone and plasma J-endorphin observed. The anaerobic intensity of the exercise session is further reflected by the concomitant large increases in blood lactate. However, consistent with previous data on hormonal responses to resistance exercise in adult males, blood lactate demonstrated few significant relationships to the hormonal changes (13). How anaerobic factors interact with the hypopituitary axis remains unclear.
These data suggest that peripheral blood lactate concentrations, per Se, do not reflect a very strong stimulatory role in the activation of the hypo-pituitary axis.
Few data are available concerning the response of 3-endorphin to heavy resistance exercise. Elliot et al.
(2) demonstrated significant increases in plasma J-endorphin/-lipotropin concentrations following a multi-set and multi-exercise resistance exercise protocol. Our data support this observation while extending to the more specific 3-endorphin fragment itself as our assay eliminated the confounding
-lipotropin fragment, which could be differentially influenced by other metabolic factors (12). The -endorphin re-
sponses along with cortisol and growth hormone suggest that the hypopituitary-adrenal-cortical axis is significantly activated in response to a weightlifting exercise session yet it is not differentially influenced by training experience or strength in young male weightlifters.
While no significant hormonal differences were observed between the stronger and the weaker groups, a trend toward higher testosterone, cortisol, growth hormone,
and 3-endorphin concentrations was observed as the mean values were generally higher for the stronger athletes. All of the subjects in this investigation were within their normal age-re-
lated ranges for testosterone concentrations (16). Each of the subjects exhibited high levels of strength (see Table 2). The absolute differences due to U. S. Weightlifting Federation ranking were small but still created two distinctly different competitive groups. Still, both of these groups would be considered to be on the high strength side of a continuum for adolescent males of similar age. Fahey et al. (3) found no significant rela-
tionships between serum testosterone to muscle strength. While testosterone is probably involved with the maturation and training adaptations of various neuromuscular adaptations, the homogeneity of strength levels in this sample may not have allowed for enough differentiation in testosterone levels.
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108
mt. J. Sports Med. 13 (1992) 109
Acute Hormonal Responses in Elite Junior Weigh tl/fters
Acknowledgements The authors would like to thank the Sport Science Division research staff, USOC, for their support and help with this project. We also would like to thank Mr. John Thrush, head coach of the National Junior Weightlifting Squad. Finally, we would like to especially thank a dedicated group of young athletes without whose efforts this project would not have been possible.
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Guezennec Y., Leger L., Lhoste F., Aymonod M., Pesquies P. C.: Hormone and metabolic response to weight-lifting training ses-
sions.IntJSportsMed7: Häkkinen K., Pakarinen A., Alén M., Kauhanen H., Komi P. V.: 100—105,1986.
Relationships between training volume, physical performance ca-
pacity, and serum hormone concentrations during prolonged training in elite weightlifters. ml J Sports Med 8: 61—65 (suppl), 1987.
Häkkinen K., Pakarinen A., Alén M., Kauhanen H., Komi P. V.: Neuromuscular and hormonal adaptations in athletes to strength trainingin two years. JApplPhysiot65: 2406—2412,1988. Häkkinen K,, Pakarinen A., Alén M., Kauhanen H., Komi P. V.: Neuromuscular and hormonal responses in elite athletes to two successive training sessions in one day. EurJApplPhysiol 57: 133— 139, 1988.
Häkkinen K., Pakarinen A., Alén M., Komi P. V.: Serum hormones during prolonged training of neuromuscular performance. 1985. '° EurJApplPhysiol53:287293, Hetrick G. A., Wilmore J. M.: Androgen levels and muscle hypertrophy during an eight week weight training program for
men/women. Med Sci Sports Exerc
11:
102, 1979.
21 u S. Weightlifting Federation, Men's Classification Standards. Weightlfting-USA8(1):6, 1990. 22 Vanhelder W. P., Radomski M. W., Goode R. C.: Growth hormone responses during intermittent weight lifting exercise in men. EurJApplPhysiol53: 31—34,1984.
23 Weiss L. W., Cureton K. J., Thompson F. N.: Comparison of serum testosterone and androstenedione responses to weightlift-
inginmenandwomen.EurJAppIPhYsiolSO4l34l9 1983.
William J. Kraemer, Ph. D.
Associate Professor Center for Sports Medicine Greenberg Sports Complex The Pennsylvania State University University Park, PA 16802 USA (814) 865-7109
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In summary, the primary finding of this investigation was that the amount of training experience primarily influences the responsiveness of serum testosterone concentrations to heavy resistance exercise. In addition, maximal strength capabilities, per Se, do not appear to influence hormonal responses in highly trained young males.
103
Acute Hormonal Responses in Elite Junior Weightlifters W. J. Kraemert , A. C. Fryt, B. .J. Warren2, M. H. Stone2, S. J. Fleck3, J. T. Kearney3, B. P. Conroy4, C. M Maresh4, C. A. Weseman4, N. T Triplett', S. E. Gordon1 'Center for Sports Medicine, The Pennsylvania State University, University Park, PA, 16802 USA -Department of Health, Leisure and Exercise Science, Appalachian State University, Boone, NC, 28608 USA 3Sports Science Division, U. S. Olympic Committee, Colorado Springs, CO, 80909 USA 4Human Performance Laboratory, Department of Sport, Leisure, and Exercise Sciences, The University of Connecticut, Storrs, CT, 06268 USA
W. J. Kraerner, A. C. Fry, B. J. Warren, M. H.
Stone, S. J. Fleck, J. T. Kearney, B. P. Conroy, C. M Maresh, C. A. Weseman, N. T. Triplelt and S. E. Gordon, Acute Hormonal Responses in Elite Junior Weightlifters. IntJSportsMed,Vo113,No20,pp103—lO9,l992. Accepted after revision: June 10, 1991
To date, no published studies have demonstrated resistance exercise-induced increases in serum testosterone in adolescent males. Furthermore, few data are available on the effects of training experience and lifting performance on acute hormonal responses to weightlifting in young males. Twenty-eight junior elite male Olympic-
style weightlifters (17.3±1.4 yrs) volunteered for the study. An acute weightlifting exercise protocol using moderate to high intensity loads and low volume, characteristic of many weightlifting training sessions, was examined. The
plasma fI-endorphin, and whole blood lactate. The exercise protocol elicited significant (p 0.05) increases in each of the hormones and whole blood lactate compared to pre-exercise measures. While not being significantly older, subsequent analysis revealed that subjects with > 2 years train-
ing experience exhibited significant exercise-induced increases in serum testosterone from pre-exercise to 5 mm
post-exercise (16.2±6.2 to 21.4±7.9 nmolll, while those with 2 years training showed no significant serum testosterone differences. None of the other hormones or whole blood lactate appear to be influenced by training experience. Exclusive from years of training, strength levels did not influence hormonal response patterns as lifters classified as strong showed no differential responses from those classified as weak as both groups demonstrated hormonal increases with acute exercise. These data suggest that training experience in elite adolescent weightlifters is most
influential when examining the hypopituitary-gonadal training adaptations.
exercise protocol was directed toward the training associated with the snatch lift weightlifting exercise. Blood samples were obtained from a superficial arm vein at 7 a. m. (for baseline measurements), and again at pre-exercise, 5 mm post-, and 15 mm post-exercise time points for determination of serum testosterone, cortisol, growth hormone,
Introduction
Chronic resistance training may alter the mechanisms involved with cybernetic control of acute neu-
roendocrine responses and exercise adaptations (7, 14). Häkkinen and co-workers (7) have demonstrated increased baseline testosterone levels in elite adult male weightlifters over the course of two years of resistance training. Conversely, shorter training periods (one year or less) have shown no base-
line changes in serum testosterone concentrations (6, 9, 10, 18). Acute increases in serum concentrations of cortisol (5, 8), testosterone (5, 13, 23), growth hormone (13, 14, 15, 18, 22), and plasma 3-endorphin (2) have been observed consequent to various resistance exercise protocols in adult males.
Key words
Testosterone, cortisol, growth hormone, endorphin, blood lactate, resistance exercise, strength, an-
aerobic
The acute hormonal responses of adolescent individuals to heavy resistance exercise is less understood. Fahey et al. (3) observed no increases in serum testosterone concentrations immediately following a heavy resistance exercise session in high school males (16.0 0.8 yrs). In contrast, they did observe increases in serum testosterone in both ex-
perienced and inexperienced college-aged males after a resistance exercise session. Lukaszewska et al. (14) have shown increases in growth hormone and cortisol in adolescent males after a weightlifting session. Such limited data indicate that for the hormone testosterone, younger males are unable to stimulate exercise-induced increases in serum concentrations with resistance exercise. Still, with such limited data on hormonal
responses to heavy resistance exercise in younger men, no definitive pattern of any hormonal response can be readily gleaned from the literature.
lnt.J.SportsMed. 13(1992)103—109 GeorgThieme Verlag StuttgartNew York
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Abstract
104 mt. J. Sports Med. 13(1992)
W. .1. Kraemer, A. C. Fry, B. J Warren, M. H. Stone, S.f. Fleck, I. F Kearney ezal.
Table 1 Subject character istics (n = 28) Variable
17.3± 1.4 167.2± 2.8 67.8 11.9 2.8
pre-exercise (2 p.m—S p.m.)
* 5 mis post
-j
15 mm post
1.5
3.6± 1.0 6.2
L
7am.
exercise
2.2
63.5 10.4 145.1
94.2± 19.2 120.2±23.5 213.0±42.4
Therefore, the primary purpose of this investigation was to determine the effects of an acute weightlifting exercise session on a wide spectrum of hormonal responses in elite adolescent male weightlifters. Additionally, we were also interested in the influence of maximal strength and training experience on the hormonal response patterns. Methods Twenty-eight participants in a junior age group national weightlifting training camp volunteered as subjects for this investigation (X±SD; age=l7.3± 1.4 yrs,
height= 167.2±2.8 cm, body weight=67.8± 11.9 kg).
Prior to the study, each subject was informed of the possible experimental risks and signed an informed consent document (both subject and parent if under the age of 18 yrs). Complete descriptive data is listed in Table 1. Body density was estimated by anthropometric methods using the seven skinfold site equation of Jackson and Pollock (11). Relative fat levels were calculated by the formula of Sin (17), thus permitting the determination of fat free mass. Tanner maturity ratings were estimated from the pre-exercise testosterone concentrations
blood samples # anthropometric measures exercise protocol — 15 vertical jumps snatch lift lest 3 x 10 snatch pulls
Fig. 1 Experimental design timeline.
where one lift is featured in the training session. Warm-up ex-
ercises and heavy lifts are followed by lower intensity, high volume weightlifting exercise for conditioning. The specific exercise protocol used in this investigation consisted of fifteen maximum effort vertical jumps (VJ) performed at a clocktimed cadence of 1 every 3 seconds. During the jumps the lifters' hands were kept on the hips for all the jumps. A countermovement was allowed but no steps were permitted and therefore the leg muscles were utilized in a similar motion as in the
snatch lift. Following the jumps and a 1-minute rest period, each subject performed 10 single warm-up repetitions using the snatch lift with 40% of their best competitive 1 repetition maximum (1 RM) performance. All lifts in this investigation were determined as a percentage of their best competitive snatch lift (1 RM). These warm-up repetitions were not timed, but were generally completed in 2—3 minutes. This was followed by another one-minute rest, after which each subject began the actual snatch lift exercise protocol. Beginning with 50% of 1 RM for the snatch lift, one repetition was performed every 15 seconds (clocked timed, verbal ques), with the load for each successive lift being increased by 5 kg. Lifting continued
junior age group national team.
until each subject missed two consecutive attempts. This was followed by a three-minute rest period, after which three sets of 10 repetitions were performed using the snatch lift high pull exercise with a load of 65% of 1 RM. In order to standardize the efforts, a clock-timed cadence and verbal ques were again given and allowed for one lift to be performed every four seconds. Each set was separated by a one-minute rest period.
Following a 12-hour fast, blood samples were obtained at 7 a. m. to determine baseline values of total testost-
Whole blood was immediately assayed in duplicate for lactate concentrations using a YSI 23L lactate ana-
erone, cortisol, growth hormone, fEl-endorphin, and whole blood lactate. Such data would allow for the examination of diurnal variations of each hormone over the experimental test day for each hormone. Approximately 15 ml of blood was obtained at each time point to assay for the hormones in this study. Blood samples were obtained from an antecubital arm vein by venipuncture using a 21 gauge needle and vacutainer assembly and vacutainer collection tubes. Serum vacutainers contained no preservatives and the plasma vacutainer con-
lyzer (Yellow Springs Inc., Yellow Springs OH). Blood samples were centrifuged for 15 mm at 1500 >< g (4 °C for plasma and room temperature for serum) processed and
(4), with all testosterone concentrations falling within the ranges expected for the subjects' respective ages (16). All athletes were selected for the training camp based on previous
drug tested competitive performances, for which none had tested positive. Included in the group were members of the
tained EDTA [7.2 mg-S mF 1of whole blood]. The subjects reported for the actual exercise test session between 2—5 p. m. (see Fig. 1). Pre-exercise blood samples were taken prior to exercise and again at 5 and 15 minutes following the exercise session.
serum and plasma was stored at —90 °C until assayed. Plasma and serum samples were thawed only once before analyses. Radioimmunoassays for each hormone were performed in duplicate and sample identification was decoded only after analyses were completed (i. e., blinded analysis procedure). Tmmunoreactivity values were determined with a gamma counter (Searle 1195, Analytic Series Inc.) and a Beckman 5500 data reduction frocessor. Plasma J3-endorphin was determined
using an i radioimmunoassay (IncStar, Stillwater, MN), which has been previously described in detail (12). With the
preliminary extraction procedures utilized in this assay, crossreactivity with fEl-lipotropin was less than 5%. The intraThe exercise session was designed to simulate a
assay coefficient of variation was 8.1 % and the inter-assay
typical progression during a weightlifting training session
coefficient of variation was 12.0 %. Serum human growth hor-
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Age (yrs) Height (cm) Body weight (kg) Years Trained Estimated Tanner Maturity Rating Relative Fat (%) Fat Free Mass (kg) 3 RM Squat (kg) 1 RM Snatch (kg) 1 RM Clean and Jerk (kg) Total [snatch + clean and jerkl (kg)
*
Intl SportsMed. 13 (1992) 105
Acute HormonalResponses in Elite Junior Weightlflers
Fig. 2 Mean (± SD) hormonal and lactate response patterns of highly experienced (> 2 yrs training; n = 16) and less experienced ( 2 yrs training; n = 12) junior age group Olympic weightlifters are presented. ......U nderlined bar values represent no significant (p > 0.05) differences between combined group data across various time points (main effect). = p < 0.05 between groups A 7 a. m. > pre-ex, 5 mm, and 15 mm for 2 yrs experience group B = 7 a. m. > pre-ex, and 15 mm for >2 yrs experience group C = 5 mm > pre-ex value for > 2 yrs experience group
0 E
0
C
C
=
C
0
0
0
00
a)
a) )0
a) a)
0.175
2years
.
>2years
0.150
C)
0
0.125 0)
C
0
0.100
E
0 a)
0 a)
0.050
0.025 0.000
n
I
a
0
+ :44
1
C)
4 a) N
7a.m. pre-ex
rnin
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0.075
15 mm
0
0
E
0.
E a
C
-c
0)
a. 0
4° C)
-C
a)
C
P 15
7a.m. pre-ex
mone was determined in duplicate using a liquid phase, double anti-body radioimmunoassay technique (ICN Biomedicals, Inc., Carson, CA). Serum cortisol and testosterone
were analyzed in duplicate using a solid phase radioimmunoassay technique (ICN Biomedicals, Inc., Carson, CA). For serum growth hormone, testosterone, and cortisol the intra-assay variances were less than 3.0% and the inter-assay variances were less than 5.8 Va. Testosterone to cortisol ratios were determined to examine the changes in the theoretical anabolic to catabolic changes during the day and in response to the weightlifting exercise session (9). Plasma volume shifts for this exercise protocol were calculated to be less than 10°/I and did not effect the response patterns of this study (1). Serum
hormone concentrations were not corrected for plasma
5 mm
15 mm
tion of the investigation. Neither subjects nor the investigators knew subject classifications during the study. In order to determine the possible effects of strength levels on the acute hormonal responses to the exercise session, subjects were divided
into strong (n 11) and weak (n= 17) groups. This was accomplished by using a classification system developed by the
U. S. Weightlifting Federation (21) that corrects for their weight class, thus allowing subjects to be categorized as master
or class I lifters (strong) and class IT or III lifters (weak). A balanced design existed for the number of subjects in each of four cells created by this dual classification of training level and strength level.
A two-way analysis of variance (2 x 4)
volume shifts in this investigation.
[group x time] with repeated measures was utilized for statistical treatment of the data. Post-hoc analyses included one-way
To determine the effects of training experience on the acute hormonal responses to the exercise session, the subjects were divided into highly experienced (n== 16; >2 years supervised weightlifting) and less experienced (n 12; 2 years supervised weightlifting) groups after the comple-
(1 x 4) repeated measures analyses of variance and independent Tukey tests. Independent t-tests were used to determine significant differences between the groups (highly experienced vs less experienced; strong vs weak) for all physical performance measures. Pearson product-moment correla-
106 mt. J. Sports Med. 13 (1992)
W. I Kraemer, A. C. Fry, B. J. Warren, M. H. Stone, S. J. Fleck, J. T Kearney et al. Fig. 3 Mean (± SD) hormonal and lactate response patterns of strong and weak
35
30 0 E
C
0 U)
t 0 0
10
groups of junior age group Olympic weightlifters.
..__Underlined barvalues represent no significant (p> 0.05) differences between combined group data across various time points (main effect). D = 7 a. m., and 5 mm > pre-ex for the
strong group E = 7 a. m. > pre-ex, 5 mm, and 15 mm for the weak group
7am, pre-ex
5 mm
15 mm
F = 5 mm > pre-ex for the weak group
0.175
• strong weak
0.150
0) rI.
)0
0 0 0 C 0 0 (0 0 U)
0.125
0)
C
0
0.100
E
0.075 0.050 0.025 0.000
ui.i ii 7am. pre-ex
5 mm
0 .0 .0 a
0
0)
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0
15 mm
0 E
0 E E 0
'C
a.
0 0 C
01
0 )0
P
tions were used to examine bi-variate relationships between blood lactate concentrations and the hormonal responses. Significance in this investigation was chosen as p < 0.05. The data are presented as means 1 standard deviation. Results
When comparing the groups separated by the experience classification, no differences were observed be-
tween experience groups except for the number of years trained. Comparisons of the strong and weak classification groups, as expected, demonstrated that the strong group had superior performances on all the strength-related variables. It should be noted that although the strong group lifted heavier weights during the exercise session, the loads represented a similar percent of 1 RM as that lifted by the weak group. The strong group also performed a significantly greater number of attempted snatch lifts, due primarily to the greater absolute loads lifted. This is explained by the absolute increments of loading utilized in the exercise test session (i. e., 5 kg) that resulted in a lower relative % increase for the strong group based
on maximum weight lifted during the snatch test (i. e., = 5.1 % increment for the strong group and 6.7% increment for the weak group). The strong group was also significantly older than the weak group, but was apparently not more mature as indicated by pre-exercise testosterone levels (4). These group comparisons are shown in Table 2.
Comparisons of training experience ( 2 yrs
vs > 2 yrs) on the hormonal response patterns and blood lactate are illustrated in Fig. 2. Only one significant difference between groups was revealed at any one time point for any of the
variables observed (i. e., TES/CORT at 7 a. rn). However, changes across time were evident for each variable when both groups were combined (i. e., main effect). These are indicated by the underlined bars in Fig. 2, and indicate significantly dif-
ferent hormonal and lactate concentrations. As expected, 7
a. m. baseline values for testosterone were significantly greater than all other sample time values. Furthermore, significant increases from pre-exercise to 5 minutes post-exercise were observed for all of the hormones and whole blood lactate.
Both serum testosterone and serum growth hormone main-
Jut. J. Sports Med. 13(1992) 107
Acute HormonaiResponses in Elite Junior Weigh t4fters
exercise. On the other hand, plasma -endorphin and whole blood lactate significantly decreased from 5 minutes to 15 minutes post-exercise. Although both serum testosterone and cortisol increased due to exercise, the cortisol response was greater. This resulted in a significant decrease in testosterone/cortisol ratio (TES/CORT) from 7 a. m. values to 15 minutes post-exercise values. However, no significant differences were observed from pre-exercise to 1 5 minutes post-exercise.
Significant interaction effects occurred for both serum testosterone and the TES/CORT ratio. For testosterone, the less experienced group ( 2 yrs) exhibited a significant decrease from 7 a. m. to pre-exercise, after which
serum testosterone values did not change. The more experienced group (>2 yrs) also demonstrated a significant decrease from 7 a. m. to pre-exercise but then exhibited a significant increase in serum testosterone concentrations from
pre-exercise to 5 minutes post-exercise, after which testosterone values returned to pre-exercise levels by 15 minutes
Discussion
The most remarkable finding in this investigation was that the length of resistance training experience appears to influence the exercise-induced response patterns of testosterone in adolescent males. An exercise-induced increase in serum testosterone was observed consequent to the weightlifting exercise session only in the group of elite junior weightlifters with more than 2 years of training experience. This finding is even more striking because we also demonstrated that despite a high level of performance ability and training background, the group of weightlifters with less than 2 years' training experience did not exhibit a significant exercise-induced increase in serum testosterone concentrations. The later finding is consistent with data from Fahey and coworkers (3), who did not observe any increases in serum testosterone following a heavy resistance exercise protocol (i. e., 3 sets of 5 repetition maximum loads for the bench press, seated press, and the leg press) in high-school-aged males.
Chronic exposure to resistance exercise (i. e., long-term training) may play a crucial role in stimulating an ac-
tivation of the hypopituitary-gonadal axis to resistance exercise. The mechanisms which mediate such changes remain unThe TES/CORT analysis also exhibited a sig- clear but could be related to changes in the cybernetic feednificant interaction effect due to a significant difference in the back mechanisms in the hypopituitary-gonadal axis and/or a remodelling of the testicle cell structures to promote increased 7 a. m. values, with the less experienced group having a higher ratio. All other TES/CORT responses were similar for both release (4, 19). In adult weightlifters, observations over two years by Häkkinen and co-workers (7) support this hypothesis experience groups. that chronic intense strength training is necessary to observe The responses of hormonal and blood lactate resting baseline changes in serum testosterone responses. Our data demonstrated no differences in resting baseline levels of between strength classification groups (strong vs weak) are serum testosterone between the two groups. This suggests that shown in Fig. 3. Significant changes across time were evident when both groups were combined for each variable (i. e., main the adaptational response in younger weightlifters may be more related to the neuroendocrine activation mechanisms in effect). These are indicated by underlined bars in Fig. 3. As the hypopituitary-gonadal axis, which could cause exercisepreviously observed, testosterone values at 7 a. m. were signifiinduced increases in testosterone. Alternatively, it is possible cantly greater than all other sample time values. Again, significant increases were observed for all hormonal and blood lac- that other physiological mechanisms in the body could contribute to concentrating peripheral blood levels during and tate responses from pre-exercise to 5 minutes post-exercise. As after exercise. While plasma volume shifts are a factor, other with the previous analyses, testosterone and growth hormone maintained their elevated levels at 15 minutes post-exercise, concentrating mechanisms which would regulate peripheral while cortisol continued to increase from 5 to 15 minutes post- blood concentrations might also become differentially operin more experienced lifters. It might be speculated that exercise. Again, 3-endorphin and blood lactate significantly ational decreased degradation, changes in clearance rates from tissues decreased from 5 minutes to 15 minutes post-exercise. As previously observed, TES/CORT decreased from 7 a. m. to 15 (hepatic and extra-hepatic), changes in protein transport and binding, and differential cell receptor alterations (e. g., recepminutes post-exercise. tor number and binding affinity) could all theoretically proWhen comparing strength levels, a significant duce differential responses between experienced and inexinteraction effect was observed for serum testosterone. Both perienced lifters due to training adaptations at the molecular postexercise.
the strong and the weak groups exhibited a significant decrease in testosterone from 7 a. m. to pre-exercise, as well as a significant increase from pre-exercise to 5 minutes post-exercise. However, testosterone levels for only the strong group returned to 7 a. m. concentrations by 5 minutes post-exercise.
Simple regression analysis demonstrated no systematic bi-variate relationships between blood lactate and the hormonal responses in this investigation. The only significant correlations were between whole blood lactate following exercise and 3-endorphin [5 mm post] (r = 0.31), and 1-endorphin [15 mm post] (r= 0.53) accounting for less than 29% of
the shared variance between the two variables. No other significant correlations were observed.
level.
The differences observed in this investigation attributed to length of the training experience appear to be solely related to the serum testosterone responses. This is sup-
ported by the fact that both the experienced and less experienced groups demonstrate significant exercise-induced increases in all of the other hormonal variables consequent to the weightlifting exercise session. Neither serum growth hormone and cortisol nor plasma 3-endorphin showed any differences due to training experience or strength classifications. In adult males, serum growth hormone concentrations have been shown to significantly increase in response to heavy resistance exercise stress (13, 20). The magnitude of the growth hormone
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tamed their increased levels at 15 minutes post-exercise, while serum cortisol continued to increase from 5 to 15 minutes post-
mt. J. Sports Med. 13(1992)
W. J. Kraemer, A. C. Fry, B. .1 Warren, M H. Stone, S. J. Fleck, J. T Kecirney et al.
Table 2 Comparisons of Group Characteristics (X SD) Variable
Highly Experienced
Less Experienced
(n=16)
(n=12)
17.3± 1.9 17.4±1.1 Age (yrs) 170.7± 8.1 170.7±6.4 Height (cm) 67.8± 14.7 67.8±9.9 Body Weight (kg) Relative Fat (%) 6.1 6.4± 2.4 Fat Free Mass (kg) 63.6 8.6 63.3 12.9 3.8±1.1 1.5± 0.6** Years Training Estimated Tanner 3.6±1.1 3.6± 1.0 Classification 1.5±0.6 1.8± 0.9 (1 = Master,2 = Class I, 3 = Class II, 4 = Class Ill)
Strong
Weak
(n=11)
(n=17)
18.6±0.9 172.2±6.7
71.9±9.2 6.4± 1.9
67.3 8.5 3.1
3.8±1.0 1.8±0.4
16.5± 1.0* 1695± 7.3 65.2± 12.9 6.1 61.0
2.5 11.1
2.6± 1.3 3.5± 1.0 3.2± 0,4*
Lifting Capabilities 150.2±26.7
3 RM Squat (kg)
Squat/Body Mass SquatfFFM 1 RMSnatch (kg) Snatch/BM Snatch/FFM Clean and Jerk CJ/BM CJ/LBM
2.21
2.36±0.28 97.5± 17.0
1.37±0.30 1.53±0.41 122.5±21.9 1.81
1.92±0.17 218.6±38.3 3.07±0.54 3.43±0.29
Total (kg) Total/BM Total/FFM
126.3±53.3 1.90±0.67 2.02±0.72 89.9±21.7 1.33±0.22 1.42±0.25 117.1±26.0 1.75±0.20 1.85±0.25 205.5±47.9 3.04±0.42 3.25±0.48
170.2± 17.2
2.38±0.21 2.55±0.24 111.7± 10.8 1.56±0.11
1.67±0.12 139.8± 14.7 1.95±0.10
2.09±0.12 249.6±25.1 3.48±0.21 3.73±0.22
120.3± 40.5*
1.88± 0.53 2.00± 0.57* 82.9±14.2* 1.22± 0,25* 1.36± 0.13* 107.5± 19.0*
1.67± 0.11 * 1.77± 0.14* 189.3±33.4*
2.79± 0.41* 3.11
0.24*
74.9 90.2
13.45*
Results of the 5 kg incremental snatch lift test within the exercise session
Weight Lifted (kg)
85.8 16.3
%1RM
88.1
Number of Attempts Number of Misses
7.6
8.2± 1.9
0.3±0.6
81.9 18.4 91.2 7.7 7.9± 1.9 0.5± 0.8
98.4
11.
88.3 7.0 9.4±1.6 0.3±0.5
8.2
7.2± 1,6* 0.5± 0.8
0.05 from corresponding strong classification 0.05 from corresponding highly experienced classification FFM = fat free mass (kg) BM = body mass (kg) **p
Clean and Jerk (CJ) and Snatch lifts from competitive tests, and 3 RM squat determined during the lifting camp.
response has been observed to be greater when the length of
the rest periods are short (i. e., 1 mm) and/or when large muscle group exercises are utilized (7, 8, 13). In this investiga-
tion the use of shorter rest periods and multi-joint exercises may have contributed to the large increases in serum growth hormone and plasma J-endorphin observed. The anaerobic intensity of the exercise session is further reflected by the concomitant large increases in blood lactate. However, consistent with previous data on hormonal responses to resistance exercise in adult males, blood lactate demonstrated few significant relationships to the hormonal changes (13). How anaerobic factors interact with the hypopituitary axis remains unclear.
These data suggest that peripheral blood lactate concentrations, per Se, do not reflect a very strong stimulatory role in the activation of the hypo-pituitary axis.
Few data are available concerning the response of 3-endorphin to heavy resistance exercise. Elliot et al.
(2) demonstrated significant increases in plasma J-endorphin/-lipotropin concentrations following a multi-set and multi-exercise resistance exercise protocol. Our data support this observation while extending to the more specific 3-endorphin fragment itself as our assay eliminated the confounding
-lipotropin fragment, which could be differentially influenced by other metabolic factors (12). The -endorphin re-
sponses along with cortisol and growth hormone suggest that the hypopituitary-adrenal-cortical axis is significantly activated in response to a weightlifting exercise session yet it is not differentially influenced by training experience or strength in young male weightlifters.
While no significant hormonal differences were observed between the stronger and the weaker groups, a trend toward higher testosterone, cortisol, growth hormone,
and 3-endorphin concentrations was observed as the mean values were generally higher for the stronger athletes. All of the subjects in this investigation were within their normal age-re-
lated ranges for testosterone concentrations (16). Each of the subjects exhibited high levels of strength (see Table 2). The absolute differences due to U. S. Weightlifting Federation ranking were small but still created two distinctly different competitive groups. Still, both of these groups would be considered to be on the high strength side of a continuum for adolescent males of similar age. Fahey et al. (3) found no significant rela-
tionships between serum testosterone to muscle strength. While testosterone is probably involved with the maturation and training adaptations of various neuromuscular adaptations, the homogeneity of strength levels in this sample may not have allowed for enough differentiation in testosterone levels.
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108
mt. J. Sports Med. 13 (1992) 109
Acute Hormonal Responses in Elite Junior Weigh tl/fters
Acknowledgements The authors would like to thank the Sport Science Division research staff, USOC, for their support and help with this project. We also would like to thank Mr. John Thrush, head coach of the National Junior Weightlifting Squad. Finally, we would like to especially thank a dedicated group of young athletes without whose efforts this project would not have been possible.
References
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William J. Kraemer, Ph. D.
Associate Professor Center for Sports Medicine Greenberg Sports Complex The Pennsylvania State University University Park, PA 16802 USA (814) 865-7109
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In summary, the primary finding of this investigation was that the amount of training experience primarily influences the responsiveness of serum testosterone concentrations to heavy resistance exercise. In addition, maximal strength capabilities, per Se, do not appear to influence hormonal responses in highly trained young males.
