ABSTRACT
The capacity of human skeletal muscle to adapt to repeated bouts of physical activity over time so that subsequent exercise capacity is improved is termed “physical training” (Booth & Thomason, 1991). The goal of such training for the soccer player is to induce multiple physiological and metabolic adaptations that enable the working muscles to increase the rate of adenosine triphosphate (ATP) production from both aerobic and oxygen-independent pathways, maintain tighter metabolic control (i.e. match ATP production with ATP hydrolysis), minimize cellular disturbances, and improve fatigue resistance during exercise (for a review, see Hawley 2002a). Although the major perturbations to cellular homeostasis and muscle substrate stores occur during exercise, the activation of several major signalling pathways important for chronic training adaptations take place during the first few hours of recovery, returning to baseline values within 24 h after exercise (Hildebrandt, Pilegaard, & Neufer, 2003; Pilegaard, Ordway, Saltin, & Neufer, 2000). This has led to the paradigm that many chronic training adaptations are generated by the cumulative effects of the transient events that occur during recovery from each (acute) exercise bout (Pilegaard et al., 2000; Widegren, Ryder, & Zierath, 2001; Williams & Neufer, 1996).
