Rule modification in junior sport: Does it create differences in player movement?

The Effect of Sports Rules Amendments on Exercise Intensity during Taekwondo-Specific Workouts

We aimed to compare the change in exercise response to taekwondo-specific circuit workouts before and after competition rule amendments. A total of 240 workouts in 15 elite athletes were analyzed over two years. Physiological and kinematic data were gathered with the wireless Bioharness system along with capillary blood samples for lactate concentration. Progressive exercise tests until exhaustion were periodically performed to obtain reference data. The rule changes resulted in significant increases (mainly medium or large effects) in the physiological (2.9-14.4%) and kinematic (4.8-10.1%) response to taekwondo-specific workouts. The largest increases were for peak breathing rate (12.0%), energy expenditure (6.6%), blood lactate immediately after exercise (10.2%) and at the 30th min of recovery (14.4%), and peak kinematic activity (10.1%). Significant differences between taekwondo-specific workouts and tournament combats persisted after the shift from old to new rules, ranging from 2.4 to 38.5% for physiological and from 2.9 to 15.5% for kinematic variables. The largest workout-combat differences were revealed for post-exercise (15.9%) and recovery (38.5%) blood lactate, peak (-15.8%) and relative (-15.0%) breathing rate, and mechanical (13.5%) and physiological (14.2%) intensity. Our study suggests that the rule amendments significantly modify the exercise response to discipline-specific workouts and that taekwondo-specific training sessions do not fully recreate the tournament demands in terms of physiological and kinematic load.