Effects of resistance training at different intensities of load on cross-education of muscle strength

Abstract

The objectives of this study were 1) to compare the extent of cross-transfer of high- versus low-load unilateral resistance training performed with external pacing of the movement (URTEP) and 2) to compare the time course of the two approaches. Fifty subjects were randomized to one of the following three groups: G80 [two sets at 80% and two sets at 40% of one maximum repetition (1RM), 1 concentric second and 3 eccentric seconds controlled by a metronome]; G40 (four sets at 40% of 1 RM, 1s and 3s controlled by a metronome); or CG (control group). At week 1, the G80 increased the elbow flexion 1RM (P<0.05) in contralateral arm. At week 4, both G80 and G40 increased the elbow flexion 1RM (P<0.05) in contralateral arm. However, a greater 1RM gain was observed in the G80 than in the G40 (P< .05). Thus, although higher-load URTEP seems to enhance the cross-education effect when compared to lower-load URTEP, the cross-education of dynamic strength can be achieved in the two approaches after four weeks. Many patients would benefit from cross-education of muscle strength through URPEP, even who are unable to exercise with high loads and in short periods of immobilization. 
 Novelty bullets: (1) Unilateral resistance training promotes cross-education of dynamic muscle strength. (2) However, higher-load resistance training enhances the effects of cross-education of muscle strength.

Exercise prescription and strategies to promote the cross-education of strength: a scoping review

“…This positive relationship between the training intensity and the magnitude of cross-education is supported during both volume-matched and non-volume-matched elbow flexion training. 57,64 During higher intensity training (≥ 80% 1RM) a greater magnitude of cross-education is observed when compared to lower intensity loads (≤ 40%). 57,64 Additionally, training at higher intensities may increase the rate of cross-education, showing intensity-dependent outcomes following a single week of training.…”

“…57,64 During higher intensity training (≥ 80% 1RM) a greater magnitude of cross-education is observed when compared to lower intensity loads (≤ 40%). 57,64 Additionally, training at higher intensities may increase the rate of cross-education, showing intensity-dependent outcomes following a single week of training. 64 Training intensity comparisons during lower-body training show similar results.…”

“…The intensity of resistance training is arguably the most important variable in the exercise prescription and is a key moderator of the neural adaptations that manifest from training. 27 The role of training intensity on cross-education has been examined through submaximal handgrip training, 70,79 elbow flexion, 57,64 unilateral leg press in adolescents, 5,10 and knee extension. 13 The comparison of training loads (50%, 33%, and 30%, of maximal strength) prescribed to submaximal handgrip endurance training (2 sets to failure; 5-6×/wk for 6 wks) demonstrates that higher intensity loads exhibit greater cross-education than lower intensities.…”

“…57,64 Additionally, training at higher intensities may increase the rate of cross-education, showing intensity-dependent outcomes following a single week of training. 64 Training intensity comparisons during lower-body training show similar results. 5,10,13 In adolescents performing volume-matched high intensity (5RM) or low intensity (20RM) unilateral leg press training, high-intensity training demonstrates ∼25% and 20% greater contralateral strength increases in knee extension and flexion, respectively, compared to low- intensity.…”

“…13 The available data consistently demonstrates superior cross-education effects when unilateral training is performed at higher versus lower intensities. 5,10,13,57,64,70,79…”