Table 2.
Delphi items that reached consensus
| Delphi items | Round | n (%) |
|---|---|---|
| 1. Cross-education as the term to refer to the transfer phenomenon | 1 | 24/30 (80) |
| 2. Important elements to be part of the definition | ||
| Homologous muscles | 2 | 24/30 (80) |
| 3. Theoretical models to explain the phenomenon: bilateral access (a.k.a. ‘callosal access’) or cross-activation (a.k.a. ‘spillover’) | ||
| Both models involved for skill transfer | 2 | 23/30 (77) |
| 4. Involvement of the mirror-neuron system in skill transfer | 1 | 21/28 (75) |
| 5. TMS-based parameters to be included in the ideal neurophysiologic assessment of the phenomenon | ||
| Short-interval intracortical inhibition | 1 | 21/26 (81) |
| Interhemispheric inhibition | 2 | 22/29 (76) |
| 6. Mechanisms most likely to mediate the phenomenon | ||
| Reduced interhemispheric inhibition for strength transfer | 1 | Ranked 1st |
| Reduced interhemispheric inhibition for skill transfer | 1 | Ranked 1st |
| 7. Techniques most likely to capture adaptations to unilateral training | ||
| Functional magnetic resonance imaging | 1 | Ranked 1st |
| 8. Primary motor cortex as the central nervous system site most likely to mediate/contribute to the phenomenon | 1 | Ranked 1st |
| 9. Investigating the role of muscular mechanisms with modern technologies | 2 | 26/32 (81) |
| 10. Strategies to maximize the magnitude of the transfer of strength and/or skills | ||
| Eccentric actions | 2 | 27/32 (84) |
| High-intensity training | 1 | 27/30 (90) |
| Mirror illusion | 2 | 28/32 (88) |
| 11.’13–18 sessions’ as adequate dose of training sessions* to obtain significant contralateral gains in strength | 2 | 22/29 (76) |
| 12. Need for future investigations on the time-course of the crossed adaptations to unilateral training | 1 | 26/29 (90) |
| 13. Clinical utility of the transfer | ||
| Strength transfer | 1 | 28/31 (90) |
| Skill transfer | 1 | 30/31 (97) |
| 14. Clinical scenarios that may benefit from the phenomenon | ||
| Orthopedic conditions | 1 | 23/28 (82) |
| Sport injuries | 1 | 28/30 (93) |
| 15. Potentials barriers to the clinical employment of contralateral approaches | ||
| Inadequate scholars’ and clinicians’ education/training | 1 | 26/30 (87) |
| Lack of studies assessing the clinical importance and meaningfulness of the crossed gains (i.e., minimal important difference) | 1 | 26/30 (87) |
| 16. Regarding the warning that contralateral training may enhance interhemispheric imbalance and strength/skill asymmetry, asymmetry is less important if there are benefits for the more-affected limb** | 1 | 19/25 (76) |
| 17. Need to develop a road map (i.e., scoping review) to critically appraise the clinical potential of the phenomenon | 1 | 28/32 (88) |
TMS transcranial magnetic stimulation, a.k.a. ‘also known as’
*With a standard frequency of 3 sessions/week. Questions 6–8 were presented as ranking items, with consensus reported in the table only for the item first in rank
**Item framed with reference to unilateral impairment of neurological origin, mainly stroke