Victor R. Edgerton passed away on Wednesday 25 March 2026 at the age of 85. ‘Reggie’ was known to many of us as an innovative, thoughtful and productive physiologist whose science was translational before translational medicine was a popular buzzword. As was obvious from the southern drawl, Reggie was raised in North Carolina, in a modest family where ‘science as a profession’ was not really a thought. Reggie had experienced polio as a child and was fascinated by the workings of the human body. He also had a deep interest in sports that naturally led him to pursue graduate degrees in Physical Education, first a master's degree at the University of Iowa and then a doctoral degree at Michigan State University. This was also in the days before ‘Exercise Science’ was actually a science. After receiving his PhD, he accepted a faculty appointment at the University of California, Los Angeles in 1968, in the Department of Kinesiology, which then, in 1992, became the Department of Physiological Science (now the Department of Integrative Biology and Physiology). Reggie and his colleagues redefined the scientific basis of exercise with basic studies in animal models that changed the scientific landscape for exercise-related organizations such as the American College of Sports Medicine and the American Physiological society. The groups were basically forced to accommodate Reggie and his colleagues as they pursued the ‘basic science’ of exercise, primarily in rodent models. Reggie was a young Assistant Professor when the idea of ‘muscle fibre types’ first emerged. He was a systems physiologist at heart and took a different tack on the idea of fibre types than most. In the 1970s, fibre types were often identified based on qualitative histochemistry, yielding three to five fibre types (Brooke & Kaiser, 1970), or muscle colour, yielding two major types (Barnard et al., 1971), or contractile speed, yielding three types. It was also becoming clear at this time that fibre types were plastic, meaning that they could change in the face of altered use patterns. Reggie and colleagues proposed a fibre typing scheme that incorporated the major physiological systems into one ‘scheme’ yielding three major fibre types (Peter et al., 1972). The power of this system was that the contractile speed, oxidative capacity and glycolytic capacity of a fibre could be independently assessed and thus these types would correlate with functional measures such as speed, strength and fatigue. This fibre typing scheme also related to the way in which muscle fibres were recruited as motor units, and in 1975, Reggie collaborated with Robert Burke to integrate the fibre typing scheme with motor unit types (Burke & Edgerton, 1975). Today, after the development of myosin specific antibodies, the definitions of the major fibre types are often based on their myosin heavy chain expression (Schiaffino et al., 1989). For normal muscle, this typically correlates with the oxidative and glycolytic activities, but this method still suffers from the fact that it focuses on only the myosin heavy chain and not the physiological and metabolic properties of the fibres. As a practical physiologist, Reggie was interested in identifying the mechanistic basis of force generation in muscles. To that end, the idea of ‘muscle specific tension’ became a focus. This value, which expresses the amount of force a muscle could generate per unit muscle was highly variable in the literature in large part because investigators had expressed force per unit anatomical cross-sectional area, or force per unit mass, or force per volume or other factors. Based on anatomical insights regarding the arrangement of muscle fibres in whole muscles, Reggie and colleagues coined the phrase, ‘physiological cross-sectional area’ (PCSA), which represented the total cross-sectional area of muscle fibres calculated based on measured muscle volume and fascicle length. Importantly, this PCSA value did not necessarily correlate with any actual anatomical dimension. Using PCSA as the normalization factor, Reggie and colleagues showed that mammalian muscle generated approximately 22.5 N/cm2 of specific tension (Powell et al., 1984) across a range of muscle sizes. This value was true for all muscles of the guinea pig hindlimb with the exception of the soleus muscle leading to the concept that fast and slow muscles might have different specific tension values. That concept was later confirmed even at the motor unit level in a sophisticated experiment whereby motor unit contractile properties were measured along with the fibres belonging to that unit (Bodine et al., 1987) and more recently even in very large human muscles (Binder-Markey et al., 2023). The results of these experiments have been heavily used for biomechanical modelling of muscles across the human body (Delp et al., 1990) and for planning surgical reconstructive procedures (Lieber et al., 1992). Edgerton's motor unit experiments were performed in cat hindlimb muscles. For this reason, he and his family were actually subjected to harassment by antivivisectionists in Los Angeles, which threatened his academic career. However, these important experiments had implications for understanding motor control, a fact that led Reggie to focus on the cat locomotor system and its response to injury. Perhaps one of the most dramatic findings in this area was Edgerton's demonstration that locomotion in the paralysed cat (Lovely et al., 1986) could actually be restored by physically moving the limbs to ‘retrain’ the spinal cord to move muscles after spinal cord injury (SCI). This was a classic insight by Edgerton who understood the brain, spinal cord and muscles to be part of an integrated system that had a tremendous amount of design ‘built in’ to the various components. He believed that sensory input to the spinal cord reactivated the classic spinal cord pattern generator and could create locomotion (de Leon et al., 1998). We witnessed some of his scientific presentations, especially at the neuroscience meetings, where the idea of extending these findings to humans was scoffed at. ‘Humans aren't just big cats’ we heard. Imagine the surprise of many in the scientific and medical community when Reggie talked Christopher Reeve into recapitulating the cat experiment on Reeve himself! It worked! It's not an understatement to say that these latter experimental insights revolutionized the field of SCI rehabilitation. High intensity gait training using a variety of treadmills, exoskeletons and robotic orthotics have all improved the function of patients with SCI. In the early phases of this work, the sensory input came directly from the moving legs, but subsequent experiments show promise for using the input directly from direct stimulation either transcutaneously (Gerasimenko et al., 2015) or from implanted epidural stimulators (Harkema et al., 2011). Currently, a number of industry trials are underway to define the optimal stimulation methods and their timings to optimize patient function after SCI. Most scientists would be satisfied with accomplishments in any one of these three areas, but Reggie was not trying to simply publish papers or become famous. He was trying to solve problems – to translate scientific discovery into patient treatment. As he once jokingly told a colleague, he was more interested in ‘plantin’ trees than decoratin’ ’em!’ This is a great loss for us today when scientists are often forced to minimize risk to the point where the incremental increase in discovery has become smaller and smaller. We could all take a lesson out of the Edgerton book and think big in order to create discovery that better serves our patients. By the numbers, Reggie was a tremendously successful scientist – an h-index of 143, over 500 referred publications, and many of them cited over 100 times. His career funding record was also outstanding with longstanding funding from NASA and the NIH. Yet, while these are the objective metrics scientists often live and die by, we would prefer to remember Reggie for his ‘folksy’ (but rigorous) approach to addressing scientific questions, not being afraid to ‘think different.' He was also gregarious and willing to engage ad nauseum regarding grant reviews, scientific funding priorities, faculty mentoring and translational science. We can remember many, many hours of these stimulating and challenging discussions. We will miss those interactions and would like to memorialize Reggie as a productive, insightful, creative and bold thinker who changed the fields of muscle structure, function and plasticity, and dramatically affected the fields of motor control and recovery of neuromuscular systems from injury. Few scientists’ reach and impact extend as far as Reggie Edgerton's. He never let labels define him or lack of technical knowledge limit him. He was an exercise physiologist, a muscle biologist, a space biologist and a neurobiologist. When he wanted to learn more about the spinal cord, he took a sabbatical to Sweden to work with Sten Grillner, a renowned neurophysiologist (Grillner, 2021). He had a vision, and he never let dogma or barriers stop him from pursuing his dream. To top it all off, he was a devoted husband to Monica and adored his four sons! Thanks, Reg, we salute you and we'll miss you! Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article. None declared. Both authors have read and approved the final version of this manuscript and agree to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. All persons designated as authors qualify for authorship, and all those who qualify for authorship are listed. No funding was received for this work.
Lieber et al. (Wed,) studied this question.