Effect of Kayak Ergometer Elastic Tension on Upper Limb EMG Activity and 3D Kinematics.

Despite the prevalence of shoulder injury in kayakers, limited published research examining associated upper limb kinematics and recruitment patterns exists. Altered muscle recruitment patterns on-ergometer vs. on-water kayaking were recently reported, however, mechanisms underlying changes remain to be elucidated. The current study assessed the effect of ergometer recoil tension on upper limb recruitment and kinematics during the kayak stroke. Male kayakers (n = 10) performed 4 by 1 min on-ergometer exercise bouts at 85%VO2max at varying elastic recoil tension; EMG, stroke force and three-dimensional 3D kinematic data were recorded. While stationary recoil forces significantly increased across investigated tensions (125% increase, p < 0.001), no significant differences were detected in assessed force variables during the stroke cycle. In contrast, increasing tension induced significantly higher Anterior Deltoid (AD) activity in the latter stages (70 to 90%) of the cycle (p < 0.05). No significant differences were observed across tension levels for Triceps Brachii or Latissimus Dorsi. Kinematic analysis revealed that overhead arm movements accounted for 39 ± 16% of the cycle. Elbow angle at stroke cycle onset was 144 ± 10°; maximal elbow angle (151 ± 7°) occurred at 78 ± 10% into the cycle. All kinematic markers moved to a more anterior position as tension increased. No significant change in wrist marker elevation was observed, while elbow and shoulder marker elevations significantly increased across tension levels (p < 0.05). In conclusion, data suggested that kayakers maintained normal upper limb kinematics via additional AD recruitment despite ergometer induced recoil forces. Key pointsKayak ergometer elastic tension significantly alters Anterior Deltoid recruitment patterns.Kayakers maintain optimal arm kinematics despite changing external forces via altered shoulder muscle recruitment.Overhead arm movements account for a high proportion of the kayak stroke cycle.