Muscle metabolism and fatigue – in memory of Eric Hultman (10 October 1925–9 March 2011)

Abstract

With the opening day of the 15th International Biochemistry of Exercise Congress in Stockholm, June 2012, it was appropriate that the scientific organizing committee welcomed delegates to a symposium dedicated to the memory of Professor Eric Hultman, who spent the whole of his scientific career at the Karolinska Institute, Stockholm. The symposium, entitled ‘Muscle Metabolism and Fatigue’, highlighted the outstanding research contributions of Professor Hultman over a career spanning more than 4 decades, and also emphasized new research findings stemming from his original research contributions. This edition of the Journal of Physiology includes review articles from two of the speakers from the symposium, Niels Ortenblad and Arend Bonen, which focus on muscle glycogen availability and fatigue (Ortenblad et al. 2013), and the regulation of muscle fatty acid oxidation during exercise and training (Yoshida et al. 2013). Eric Hultman was born on 10 October 1925 in Kristinehamn, Sweden. Following completion of his secondary schooling at Kristinehamn Laroverket, Eric entered the Royal Pharmaceutical Institute, Stockholm in 1944 and was awarded the degree of Bachelor of Pharmacy in 1946. In 1948 he entered the Karolinska Institute, and was made a Bachelor of Medicine in 1955, and a Doctor of Medicine in 1956. On completion of his medical studies, Eric was employed as a junior associate in the Central Laboratory at St Eriks Hospital, and already by 1959 had published three papers on methods to determine glucose in blood, the last describing a procedure based on the colour reaction of σ-toluidine with glucose. By 1962, Eric had published 11 further papers; the last two being co-authored by his close friend and colleague Jonas Bergstrom, a PhD student at that time at St Eriks Hospital, who was notable in introducing the percutaneous muscle biopsy technique. Bringing together his earlier studies on the σ-toluidine method, with muscle biopsy sampling, Eric began a PhD in 1962 focusing on changes in muscle glycogen with exercise and diet. In 1967, Eric obtained a PhD for his thesis entitled ‘Studies on muscle metabolism of glycogen and active phosphate in man with special reference to exercise and diet’. This period marked the start of a prolific clinical scientific career at the Karolinska Institute that was to last a lifetime. This period also heralds a milestone in studies of human exercise metabolism as Eric, together with Jonas Bergstrom, undertook the first ever studies in humans concerned directly with muscle glycogen utilization during exercise, and the importance of dietary composition and timing of food intake to post-exercise glycogen restoration. From these early studies the central role of dietary carbohydrate intake to post-exercise recovery of muscle glycogen was established leading to dietary procedures employed by athletes worldwide. Eric and Lars Nilsson extended this work in the 1970s by undertaking pioneering human studies documenting liver glycogen depletion and restoration during dietary manipulation, exercise and recovery, which provided further important practical insight for athletes. In 1967 Eric, together with others, published an additional major scientific breakthrough by documenting the degradation and resynthesis of ATP in human muscle during exercise, and highlighting the role of muscle phosphocreatine in maintaining ATP turnover. This was followed 15 years later by a further pivotal paper showing muscle creatine and phosphocreatine could be increased by dietary creatine supplementation, which was subsequently shown to increase work output during high-intensity exercise. Today dietary creatine supplementation is regularly undertaken by athletes to increase exercise performance and muscle adaptation during training. In reality, these highlights do not do justice to a career of immense scientific impact. In all Eric published 310 peer-reviewed papers, 45 of these after he had ‘retired’ in 1991. Six of his papers have been cited more than 500 times. Eric, whose career involved positions at several Stockholm hospitals, including Huddinge University Hospital Karolinska Institute, was made Professor Emeritus at the Karolinska Institute in 1991. He was the recipient of an award from the Swedish Medical Society in 1966, the Mclauglin Fellowship from McMaster University in 1990, the honorary award for Biochemistry and Exercise (2000), and doctorates from the Universities of Waterloo (2001) and Guelph (2005). In addition he was made honorary Professor of Physiology at Nottingham University in 2000. Eric, in addition to being a clinical scientist, was also passionate about art and Swedish history. Eric Hultman was one of several giants in muscle biochemistry and physiology to emerge from Scandinavia during the 1960s. Athletes, coaches and exercise scientists throughout the world acknowledge these visionaries who gave birth to a new chapter in exercise science. However, arguably none has had a greater impact on this field, particularly in the area of human exercise metabolism and performance, than Eric Hultman. Revered by former friends and colleagues, he died on the 9 March 2011 in his beloved Stockholm.