Abstract
This study’s aim was to analyze muscle activation and kinematics of sled-pushing and resisted-parachute sprinting with three load conditions on an instrumentalized SKILLRUN® treadmill. Nine male amateur rugby union players (21.3 ± 4.3 years, 75.8 ± 10.2 kg, 176.6 ± 8.8 cm) performed a sled-push session consisting of three 15-m repetitions at 20%, 55% and 90% body mas and another resisted-parachute session using three different parachute sizes (XS, XL and 3XL). Sprinting kinematics and muscle activity of three lower-limb muscles (biceps femoris (BF), vastus lateralis (VL) and gastrocnemius medialis (GM)) were measured. A repeated-measures analysis of variance (RM-ANOVA) showed that higher loads during the sled-push increased (VL) (p ≤ 0.001) and (GM) (p ≤ 0.001) but not (BF) (p = 0.278) activity. Furthermore, it caused significant changes in sprinting kinematics, stiffness and joint angles. Resisted-parachute sprinting did not change kinematics or muscle activation, despite producing a significant overload (i.e., speed loss). In conclusion, increased sled-push loading caused disruptions in sprinting technique and altered lower-limb muscle activation patterns as opposed to the resisted-parachute. These findings might help practitioners determine the more adequate resisted sprint exercise and load according to the training objective (e.g., power production or speed performance).
Highlights
Rugby union is a high contact team sport played worldwide which performance depends on the complex relationship between technique, tactics, cognition and physical capacities [1]
Activation (F = 33.366; p ≤ 0.001; η2 P = 0.807).vastus lateralis (VL) activation was significantly higher at 90%
1.388; p = 0.278; ences were obtained on biceps femoris (BF) activation as load increased (F = 1.388; p = 0.278; η P = 0.148)
Summary
Rugby union is a high contact team sport played worldwide which performance depends on the complex relationship between technique, tactics, cognition and physical capacities [1]. Sprint performance is determined by the athlete’s capacity to generate and apply a great propulsive force during the acceleration phase and to maintain their maximum velocity for as long as possible during the maximum velocity phase [5] In this regard, different non-specific strength-power exercises and methods have been used for the improvement of the acceleration phase of the sprint [6,7,8]. Many coaches believe that training methods for improving sprint performance should include specific strength exercises, so that the athlete can perform the desired movement with an added load [9] This idea is supported by the training principle of specificity, which suggests that exercises should have similar characteristics to the sport’s requirements (i.e., type of action, movement patterns, velocity, muscle activation, etc.) [10]. Resisted sprint training (RST) has been used as a specific training method for the enhancement of sprint performance in rugby and other team-sports, especially in the acceleration phase [11,12,13,14]
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