Greater cross education following training with muscle lengthening than shortening

Abstract

The hypothesis was tested that the magnitude of cross education is greater following training with muscle lengthening than shortening. Changes in contralateral concentric, eccentric, and isometric strength and vastus lateralis and biceps femoris surface electromyographic (EMG) activity were analyzed in groups of young men who exercised the ipsilateral quadriceps with either eccentric (N = 7) or concentric (N = 8) contractions for 36 sessions over 12 wk. Control subjects (N = 6) did not train. Concentric training increased concentric strength 30% and isometric strength 22%, and eccentric training increased eccentric strength 77% and isometric strength 39% (all P < 0.05). Eccentric training improved eccentric strength three times more than the concentric training improved concentric strength (P < 0.05), and eccentric compared with concentric training improved isometric strength about 2 times more (P < 0.05). The eccentric group improved significantly from pre- to mid-training in eccentric and isometric strength (P < 0.05). The control group showed no significant changes (P < 0.05). Surface EMG activity of the vastus lateralis increased 2.2 times (pre- to mid-training), 2.8 (mid- to post-training) and 2.6 more (pre- to post-training) (P < 0.05) in the eccentric than concentric group. No significant changes in EMG activity occurred in the control group (P > 0.05). It was concluded that the greater cross education following training with muscle lengthening is most likely being mediated by both afferent and efferent mechanisms that allow previously sedentary subjects to achieve a greater activation of the untrained limb musculature.

Ipsilateral corticomotor responses are confined to the homologous muscle following cross-education of muscular strength

“…The submaximal and isometric contribution resulted in a 19% increase in the maximal voluntary strength of the wrist flexors of the trained limb. The increase in strength of the trained synergist muscle is consistent with previous research, which confirms that isometric strength training increases strength of the trained limb (Hortobágyi et al 1997;Zhou et al 2000;, even at training intensities of 10-20% of MVC (Laidlaw et al 1999;Kobayashi et al 2014). Such an increase in strength of the trained synergist, likely accounts for the increase in strength of the untrained synergist wrist flexors, which supports the strong correlation shown in this study.…”

Assessing Voluntary Muscle Activation with the Twitch Interpolation Technique

“…Observations of increased surface EMG [79,80,81,82,83,84] , increased motor unit firing rates [85,86] , cross education [82,87,88,89,90,91] and enhanced reflex potentiation [92,93,94] are consistent with the possibility but none provides conclusive evidence.…”

Biomechanical Response of the Upper Body during Prostration in <i>Salat</i> and the Child’s Pose: a Preliminary Study

“…During prostration, the elbows are flexed which causes a moderate lengthening effect on the muscles of the upper arm. It has been reported that lengthening exercises provide more benefits to the human musculoskeletal system than shortening exercises 21,22) . By using prostration in Salat as the case for investigation, we have proven that Salat produces an effect similar to the effect of a standard stretching exercise, the child's pose.…”