FORUM ISSUE: “Free Radicals and Physical Exercise”

The occurrence of free radicals in muscle contraction has been known from the late 1960s and early 1970s. However, major work from the University of Berkeley showed that, without doubt, free radicals have a role in causing both damage to muscles and in providing signals to regulate muscle function, especially mitochondriogenesis. Certainly, the emphasis has shifted from free radicals as causative of damage to muscle cells to free radicals as signals that modulate muscle function. In this forum issue, some of the leaders in muscle research from all over the world have contributed with very significant papers in this area.

Dr. Li Li Ji from Minnesota has put emphasis on the antioxidant effects of exercise and their role in redox signalling [1]. This fits in very well with the contribution of Dr. Vasilaki from Liverpool who has redefined the major contributors to superoxide production in contracting skeletal muscle [2]. Of course, the rate of production and the radical species formed in muscle depend very much on the type of contraction and Dr. Calbet from the University of Las Palmas, Canary Islands, Spain, shows that radicals formed in sprinting in humans play a critical role in signalling the adaptive response to sprint [3].

Exercise causes an improvement in health and Dr. Scott Powers from Florida reports on the improvements in myocardial antioxidant capacity and myocardial function associated with exercise [4]. Some of the beneficial effects of exercise depend on the modulation of the heat shock proteins and these are reported by Dr. Daniela Caporossi from Rome [5]. In many of the effects of reactive oxygen species, the production and function of nitric oxide are critical and this is specially dealt with in the contribution of Dr. Hellsten from Copenhagen [6].

Exercise has functions in very different tissues of the organism, including the brain. The beneficial effects of exercise in cognition mainly mediated by the brain-derived neurotrophic factor are dealt with by Dr. Radak from Budapest in his contribution [7]. Finally, emphasis should be put on activity rather than on intense exercise as that practised in sport and especially in competitive sport. The majority of the beneficial effects of exercise can be obtained when an active lifestyle is adopted and inactivity is a serious problem in western societies today. Dr. Delamarche from the University of Rennes has dealt specifically with these issues [8].

So the reader will find in this Forum Issue, as stated above, contributions made by some of the major scientists in the field of exercise and radicals covering a wide range of subjects and we hope that it will be useful to both the student interested in entering this fascinating field and to the well-seasoned scientist who wants to have a summary of today's most relevant topics in the fields of free radicals and exercise.

Table

Physical inactivity, insulin resistance and the oxidative-inflammatory loop	Gratas-Delamarche, Arlette
Redefining the major contributors to superoxide production in contracting skeletal muscle. The role of NAD(P)H oxidases.	Vasilaki, Aphrodite
Role of exercise-induced reactive oxygen species in the modulation of Heat Shock Protein response	Caporossi, Daniela
The redox-associated adaptive response of brain to physical exercise	Radak, Zsolt
Exercise-induced improvements in myocardial antioxidant capacity: the antioxidant players and cardioprotection	Powers, Scott K
Nitric oxide and reactive oxygen species in limb vascular function: what is the effect of physical activity?	Hellsten, Ylva
Free radicals and sprint exercise in humans	Calbet, Jose A
Antioxidant and anti-inflammatory effects of exercise: role of redox signaling	Ji, Li Li

Declaration of interest

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.