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ABSTRACT
Background:Powerlifting is abarbell sport consisting of the squat, bench
press, and deadlift.Powerlifting training and competition is highly dependent
on the immediate energy pathway, where adenosine triphosphate (ATP) is
made available by the ATP-phosphocreatine system.In Powerlifting
competition, the Wilks Coefficient is apopular and common means to
normalize performance relative to bodyweight. Therefore, the purpose of this
study was 1) to compare various markers associated with creatine content to
Powerlifter Wilks coefficient, and 2) compare these markers between males
and females.Materials and Methods:Twelve actively competing Powerlifters
(PL; n = 6M/6F) and twelve sedentary controls (CON; n = 6M/6F) were recruited
for this cross-sectional analysis.After providing consent and dietary logs,
subjects donated ~20mL blood and underwent apercutaneous muscle biopsy
from the vastus lateralis using the fine needle aspiration method.Dietary
macronutrients, serum total creatine (STC), relative serum creatinine (rCRT),
muscle total creatine (MTC), and muscle creatine transporter (SLC6A8) were
analyzed via multiple 2x2 (group xgender) analysis of variance (ANOVA) at a
significance level of p<0.05.MTC was compared to Wilks Coefficient using a
Pearson correlation coefficient at asignificance level of p<0.05.In the case of
trending significance (p<0.10), PL was further divided into intermediate (PLI;
n=5) and advanced (PLA;n=7) groups based on mean Wilks Coefficient; A 2x2
(group [PLA, PLI] xgender) ANOVA was employed to detect differences
between intermediate and advanced athletes.When homogeneity of variance
was violated, the Mann-Whitney non-parametric test was used at significance
level of p<0.05.Results:There were no significant group, gender, or interaction
effects between PL and CON for STC, MTC, or SLC6A8. Nonparametric tests
revealed asignificant gender difference between groups for rCRT (p=0.023).
There were significant gender (p=0.004)and group (p<0.001)effects between
PLI and PLA, where females and PLA demonstrated significantly greater rCRT
compared to males and PLI, respectively.Pearson correlation analysis revealed
anon-significant,low-moderate correlation between Wilks coefficient and MTC
(r = 0.488; p = 0.108). Conclusions:These results imply markers of creatine in
both muscle and serum are not predictive of performance in Powerlifting,
defined by Wilks coefficient.Overall, variations in Powerlifting performance
across gender and skill do not convincingly result from changes in biochemical
differences related to creatine metabolism.Therefore, these findings suggest
other biochemical markers (fiber type, enzymatic differences, etc.) and/or
neural efficiency underline variations in Powerlifting skill.
RESULTS
Total Creatine and Creatine-Associated Markers in Relation to Wilks
Coefficient in Both Male and Female Powerlifters
1 Exercise & Biochemical Nutrition Laboratory, Department of Health, Human Performance, &
Recreation, Robbins College of Health and Human Sciences, Baylor University, Waco, TX
CONCLUSION
CONTACT
Steven B. Machek1, Paul S. Hwang1, Thomas D. Cardaci1, Emiliya S. Suezaki1, Caelin S. Kim1,
Dylan T. Wilburn1, & Darryn S. Willoughby1, FISSN
While limited by a small subject pool, these findings
demonstrate:
•Powerlifters and sedentary controls have similar
creatine-associated markers in both the muscle
and serum, regardless of gender.Only rCRT was
greater in females (all groups) and in advanced
Powerlifters.
•Tot a l muscle creatine content is not a significant
predictor of Powerlifting performance.
Steven Machek, MS, CSCS
Email: steven_machek2@baylor.edu
@stretch_rx
Darryn Willoughby, PhD,
FISSN, FACN, FACSM, FASEP
Email: darryn_willoughby@baylor.edu
@doctordarrynandvickie
Although Powerlifting is heavily dependent on the ATP-phosphocreatine
system for energy provision, creatine-associated markers are not
significantly augmented in competitive Powerlifters relative to sedentary
controls. Therefore, we posit that Powerlifting-associated adaptations are
ostensibly defined by changes in other biochemical markers (i.e. enzymatic
or skeletal muscle fiber type), and/or neural adaptations.
Consent
This poster uses data from
the OpenPowerlifting project,
https://openpowerlifting.org.
SUBJECTS
METHODS
ACKNOWLEDGEMENTS
DEXA
Venipuncture
FNA Biopsy
(VL)
48h Diet
Records
Protein,
carbohydrate, fat, &
fiber intake (g/kg bw)
Height, weight, BMI,
& BF%
Serum total creatine
& creatinine
Muscle total creatine
& SLC6A8
MEASURES
Powerlifters (PL; n=12)
Controls (CON; n=12)
•6 males & 6
females
•Actively competing
(sanctioned PL
meet < 12 months +
engaged in PL
training)
•Wilks verified by
OpenPowerlifting
•6 males & 6
females
•Sedentary based on
ACSM guidelines (<
30 mins/day, < 3
days/week, over the
last 3 months)
ELISA
Descriptive
ANALYSIS
0
0.5
1
1.5
2
2.5
3
3.5
Mean
(M)
Mean
(F)
Mean
(M+F)
Mean
(M)
Mean
(F)
Mean
(M+F)
nmol/mg
PL CON
Total Muscle Creatine Levels
0
0.05
0.1
0.15
0.2
0.25
Mean
(M)
Mean
(F)
Mean
(M+F)
Mean
(M)
Mean
(F)
Mean
(M+F)
nmol/μL
PL CON
Serum Total Creatine Levels
0
0.05
0.1
0.15
0.2
0.25
Mean
(M)
Mean
(F)
Mean
(M+F)
Mean
(M)
Mean
(F)
Mean
(M+F)
nmol/mg
PL CON
Muscle SLC6A8 Levels
R² = 0.23809
1
1.5
2
2.5
3
3.5
320 340 360 380 400 420 440
MTCr Content (nmol/mg)
Wilks Coefficent
Powerlifter Muscle Creatine Content x Wilks Coefficient
(p = 0.108)
0
0.001
0.002
0.003
0.004
0.005
0.006
nmol/μL·kg
Relative Serum Creatinine
#
†
* Significant
gender effect
(p=0.023).
Females have
greater rCRT
vs males
across both
PL & CON
*
# Significant
gender effect
(p<0.001).
Females have
greater rCRT
vs males
across both
PLI & PLA
† Significant
group effect
(p=0.004),
Advanced
powerlifters
(PLA) have
greater rCRT vs
intermediate
powerlifters (PLI)
PLA =
Wilks ↑405.5
PLI =
Wilks ↓405.5
You may download a copy of the data at:
http://gitlab.com/openpowerlifting/opl-data
† Significant group difference between PLA & PLI (p<0.05)
* Significant group difference between PL & CON (p<0.05)