Summary of an article on glycogen content before and immediately after a high intensity weightlifting session in elite powerlifters and Olympic weightlifters.
10 male competitive power and Olympic weightlifters aged 24 ± 4 years with average body weight of 95 ±8 kg, 7 ± 4 years of experience in strength sports and personal bests for squat at 210 ± 25, bench 150 ± 18, and deadlift 243 ± 29 kg (Denmark).
Experimental study. Participants ate a standardized meal (~560 kcal) and 1.5 hour later performed high intensity resistance exercise session:
- warm-up (involving dynamic stretching)
- 3 lower body exercises (up to 70-75% of RM):
- back squat
- deficit deadlift (10 cm)
- rear foot elevated split squat
2 muscle biopsies: before and immediately after the exercise session
- body composition via DEXA
- muscle biopsy from the middle portion of vastus lateralis muscle:
- myosin heavy chain (MHC) distribution
- total mucle glycogen content
- subcellular glycogen localization
- muscle lactate
- fibre type
myosin heavy chain distribution was 50% MHCI, 48% MHCIIa and 2% MHCIIx
muscle glygogen concentration decreased from 398 (mmol kg dw-1) before the exercise session to 249 after the exercise session (change 150)
exercise session caused 33% decrease in intermyofibrillar glycogen only in type I fibres. In type II fibres glycogen decreased in intermyofibrillar, intramyofibrillar and subsarcolemmal localizations. After the exercise session intramyofibrillar glycogen amounts were high in type I fibers but very low in type II.
intermyofirillar glycogen amounts were around 80% of all glycogen content in both fibres types (10% intramyofibrillar, 10% subsarcolemmal).
muscle lactate concentration increased from 7.3 (mmol kg dw-1) before the exercise session to 32.1 after the exercise session (change 340%)
after the exercise, glycogen particles were smaller. - Also, in most glycogen-depleted fibres after exercise session, small crystal-like structures appeared in intermyofirillar and subsarcolemmal spaces.
Take home message
Hokken R, Laugesen S, Aagaard P, Suetta C, Frandsen U, Ørtenblad N, Nielsen J, Nielsen J. Subcellular localization-and fibre type-dependent utilization of muscle glycogen during heavy resistance exercise in elite power and Olympic weightlifters. Acta Physiologica. 2020 Sep 22:e13561.