Basal Markers of Inflammation, Muscle Damage, and Performance during Five Weeks of Pre-Season Training in Elite Youth Rugby League Players

Objectives: this study examined changes in basal biochemical markers of immune function and muscle damage, as well as physical performance during a typical pre-season training block in preparation for the Australian national youth rugby league competition.

Methods: twelve elite youth (i.e., 18-20 yrs.) rugby league players completed 5 weeks of physical training that included 10-12 sessions per week. Anthropometry, sprint speed, anaerobic power, leg power, upper- and lower-body strength were measured pre- and post-training. Venous blood was assessed for interleukin (IL-1b, IL- 10, IL-6, TNFα) and Creatine kinase (Ck) concentrations at weekly intervals.

Results: IL-1b and IL-10 concentrations were reduced from baseline after three and four weeks, respectively whereas IL-6 and TNF-α concentrations did not change over the 5-week period. Ck was increased above baseline after three weeks of training and returned to baseline at 5 weeks. Maximal bench press, hack squat, bench pull, and skinfold thickness were all improved after the 5-week training period.

Conclusion: Early increases in Ck may indicate muscle damage in response to an increased volume of physical activity or unaccustomed exercise, while a return to baseline Ck levels may indicate adaptation. Increases in muscle strength confirm positive muscle adaptation and the training resulted in a reduction in basal IL-10 and TNF alpha production which could be characteristics of normal training response. From a practical perspective, the program employed in this study provided a useful training plan to increase physical qualities, and adaptation to muscle damage.