Changes in Skeletal Muscle Glycogen Content in Professional Soccer Players before and after a Match

Abstract

INTRODUCTION: Proper glycogen stores are an essential element in athletic performance as shown in the scientific literature for many years. Recently, the role of glycogen in controlling muscle contraction has been shown as glycogen regulates calcium release from sarcoplasmic reticulum which could interfere with performance. However, regular assessment of glycogen content in athletes has not been possible due to the invasive nature of muscle biopsies or the cost of nuclear magnetic resonance spectroscopy (NMRS). Recently, we have developed and validated a novel methodology to assess muscle glycogen through high frequency skeletal muscle ultrasound in a fast, portable and non-invasive manner (1). In this study we evaluated the changes in skeletal muscle glycogen content in professional (MLS) soccer players after a soccer match. METHODS: 9 professional soccer players (MLS) (189.2 ± 9.1 cm, 74.1 ± 7.6 kg) from different positions were assessed for skeletal muscle glycogen in the rectus femoris (RF) muscle before and after a game (all played the entire game) through high frequency ultrasound scans using MuscleSound® technology. PURPOSE: To assess changes in skeletal muscle glycogen before and after a professional soccer game. RESULTS: Average RF glycogen content decreased from 68.3 ± 7.9 points (MuscleSound® score points) before the game to 55.6 ±9.1 points after the game (p=0.006). All players decreased glycogen content at various rates, -7.2 to -40%. CONCLUSION: During a soccer game skeletal muscle glycogen content decreases at various rates among players which could be attributable to different factors such as metabolic differences in substrate utilization, game demand and/or differences in carbohydrate replacement during the game. The assessment of skeletal muscle glycogen in soccer players could be beneficial to individualize nutrition during the game.