Pathway-Specific Neural Adaptations to Strength Training

Early improvements in muscle strength occur before substantial hypertrophy and are therefore strongly influenced by neural adaptation. Most human research has focused on the corticospinal tract, even though voluntary force emerges from interactions among cortical, brainstem, spinal and motor-unit mechanisms. Emerging evidence suggests that neural responses may also depend on how strength training is performed. Metronome-paced training has been associated with increased corticospinal excitability, whereas self-paced and isometric training can produce comparable strength gains without the same corticospinal signature. It is not known whether this apparent modality-specific response generalises across the body. Muscles involved in fine, independent movement receive comparatively dense corticospinal projections, while muscles supporting posture and locomotion may draw more heavily on distributed descending and brainstem pathways. Consequently, a training method that produces a strong corticospinal response in the hand or upper limb may not produce the same adaptation in a lower-limb muscle. Ageing adds a second important dimension because corticospinal integrity declines with age, while other descending pathways may contribute increasingly to force production. This PhD will test whether the neural adaptations to strength training are shaped jointly by training modality, muscle function and age. The project will combine transcranial magnetic stimulation (TMS), startling acoustic stimulation and SAS-TMS as indirect probes of descending pathway contributions, high-density surface electromyography (HD-sEMG) with motor-unit decomposition, and laboratory measures of strength and rate of force development. The final experimental scope will be refined with the successful candidate to ensure that the programme is feasible, adequately powered and aligned with their expertise.