52.4±5.1 ml/kg/min) underwent a resting muscle biopsy from their right vastus lateralis (VL) then completed a HIIT ... Significant phosphorylation of TBC1D4 was also detected in MHC I at 90 min post- exercise compared to ... 48 hr no exercise.
Fiber Type-Specific Activation of AMPK Following Acute High Intensity Interval Exercise in Concurrently Trained Men
Kinesiology
James R.
1 Bagley ,
Kara K.
2 Lazauskas ,
Irene S.
2 Tobias ,
Jeremy
2 Siu ,
Nathan
2 Serrano ,
Cameron
2 Yen
& Andrew J.
2 Galpin
1 Muscle
Physiology Laboratory, Department of Kinesiology, College of Health & Social Sciences, San Francisco State University 2 Biochemistry & Molecular Exercise Physiology Laboratory, Center for Sport Performance, California State University, Fullerton
METHODS
0 min
Rest
180 min
90 min
0.9
0.6
0.3
Rest
0 min
90 min 180 min 90 min 180 min
I I IIa II IIa II IIa IIa II IIa IIa
1.5
IIa IIa
1.0
1.2
0.9
0.6
0.5
0.3
0.0
0.0
^^^
8
6
4
2
48 hr no exercise 12 hr food/caffeine fast No medications or PEDs Standardized meal Food log for 7 days prior Hydration check
?
Fast
Visit 1: VO2max test and anthropometrics Visit 2: biopsies/HIIT experiment (7-14 d after Visit 1) 4 vastus lateralis biopsies (alternating right, left, right, left) 6 HIIT rounds, cycle erg. (~100% VO2max for 1.5 min, 40% for 2.5 min) Gas exchange monitored during HIIT
B) 1.4
TBC1D1 Expression
Rest
0 min
Rest
0 min
90 min
I
I
I I
IIa I IIa
90 min 180 min
IIa I IIa
180 min
IIa I IIa
I
IIa IIa
** *
1.0
0.8
0.6
TBC1D1 Phosphorylation
0.4
0.2
A) Rest
5
4
*** ^^^
***
Rest
post-Ex 0min
0 min
90post-Ex min 90min
post-Ex 180 180min
IIa I
IIa I
IIa
***
TBC1D4 Expression
5.0
Rest
0 min
post-Ex 9090min min
min
post-Ex
min 0 min 90 90min
post-Ex 180 180min
1.0
0.8
0.6 ***
***
***
***
0.4
***
***
*** 4.0
***
3.0
2.0 ^^
^
1.0
0.0 Rest
post-Ex 180 180min
TBC1D4 Phosphorylation
MHC IIa
0.2
***
post-Ex 0min
post-Ex 0min
min
0.0 Rest
Rest
post-Ex 0min
post-Ex min 0 min 90 90min
post-Ex 180 180min
Rest Rest
post-Ex 0min
post-Ex min 0 min 90 90min
min
min
Figure 6: A) Representative CNIA lane view images of TBC1D1 (B) expression and (C) phosphorylation in MHC I vs. MHC IIa fibers before and after HIIT. Significance: * (relative to MHC I), ^ (relative to Rest).
ABSTRACT
post-Ex 180 180min
min
Figure 7: A) Representative CNIA lane view images of TBC1D4 (B) expression and (C) phosphorylation in MHC I vs. MHC IIa fibers before and after HIIT. Significance: * (relative to MHC I), ^ (relative to Rest).
CONCLUSIONS Preserve
Isolate
Dissolve
80 60
9 participants 4 time points 30 fibers per biopsy = 1,080 fibers
40 20 0
I
I/IIa
IIa
IIa/IIx
SDS-PAGE
MHC I Select and Combine Fibers
9 participants, 4 time points 2 fiber types, = 72 samples
MHC IIa CNIA Analysis Tubulin
HIIT exercise induced: 1. FT-specific activation of AMPK 2. FT-specific differences in phosphorylation of AMPKα and all three substrates measured 3. Delayed phosphorylation responses in TBC1D1 and TBC1D4 Application: Athletes with different fiber type compositions may require different post-exercise nutritional timing strategies.
B)
A) MHC I
Liquid N2
Biopsy FT Percemtage
PURPOSE: AMP-activated protein kinase (AMPK) is an energy-sensing regulator of cellular metabolism that is activated during acute exercise. Previous human skeletal muscle studies analyzed AMPK activation in mixed fiber type (FT) biopsy samples, though recent investigations show that AMPK’s properties are dependent on myosin heavy chain (MHC) FT (i.e., slow- vs. fast-twitch). The purpose of this study was to assess the phosphorylation of AMPK and three of its substrates (markers of AMPK activity), ACC, TBC1D1 and TBC1D4, in slow (MHC I) vs. fast (MHC IIa) skeletal muscle fibers from concurrently trained men following acute high intensity interval training (HIIT) exercise. METHODS: Nine concurrently trained males (age 31±2 y; height 178±9 cm; mass 84±10 kg; VO2max 52.4±5.1 ml/kg/min) underwent a resting muscle biopsy from their right vastus lateralis (VL) then completed a HIIT bout consisting of 6 rounds (Intervals: 1.5 min at 90-100% VO2max, then 2.5 min at ~40%). A second biopsy (left VL) was performed immediately after completion of the final exercise round with a third and fourth biopsy collected at 90 min and 180 min post-HIIT. Single muscle fibers were mechanically isolated for MHC analysis via SDS-PAGE to identify FT and combined into MHC I and MHC IIa pools of 5-8 fibers. FT-specific phosphorylation of AMPKα, ACC, TBC1D1 and TBC1D4 was quantified via capillary nanoimmunoassay (CNIA). RESULTS: AMPKα phosphorylation was significantly (p
